10-Q

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2022

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from _______ to ________

Commission file number 001-39525

ESS Tech, Inc.

(Exact name of registrant as specified in its charter)

Delaware	98-1550150
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)
26440 SW Parkway Ave., Bldg. 83
Wilsonville, Oregon	97070
(Address of Principal Executive Offices)	(Zip Code)

(855) 423-9920

Registrant's telephone number, including area code

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $0.0001 par value per share	GWH	New York Stock Exchange
Warrants, each whole warrant exercisable for one share of common stock at an exercise price of $11.50	GWH.W	New York Stock Exchange

Securities registered pursuant to section 12(g) of the Act: None

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports); and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐ 

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes  ☒   No  ☐ 

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Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		Emerging growth company	☒

    

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).     Yes ☐   No  ☒

As of May 9, 2022, the registrant had 152,654,728 shares of Common Stock, par value $0.0001, issued and outstanding.

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TABLE OF CONTENTS

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS
Part I – Financial Information
Item 1. Financial Statements	4
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations	22
Item 3. Quantitative and Qualitative Disclosures About Market Risk	27
Item 4. Controls and Procedures	28
Part II – Other Information
Item 1. Legal Proceedings	29
Item 1A. Risk Factors	29
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds	61
Item 3. Defaults Upon Senior Securities	61
Item 4. Mine Safety Disclosures	61
Item 5. Other Information	61
Item 6. Exhibits	62
SIGNATURES	63

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q, including, without limitation, statements in “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations,” includes forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These forward-looking statements can be identified by the use of forward-looking terminology, including the words “believes,” “estimates,” “anticipates,” “expects,” “intends,” “plans,” “possible,” “may,” “might,” “will,” “potential,” “projects,” “predicts,” “continue,” “could,” “would” or “should,” or, in each case, their negative or other variations or comparable terminology. These words and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. These forward-looking statements, which are subject to risks, uncertainties and assumptions about us, may include projections of our future financial performance, our anticipated growth strategies and anticipated trends in our business.

These statements are based on management’s current expectations, but actual results may differ materially due to various factors, risks, and uncertainties, including, but not limited to:

•our financial and business performance, including financial projections and business metrics;

•changes in our strategy, future operations, financial position, estimated revenues and losses, projected costs, prospects and plans;

•the implementation, market acceptance and success of our technology implementation and business model;

•our ability to scale in a cost-effective manner;

•developments and projections relating to our competitors and industry;

•the impact of health epidemics, including the COVID-19 pandemic, on our business and the actions we may take in response thereto;

•our expectations regarding our ability to obtain and maintain intellectual property protection and not infringe on the rights of others;

•expectations regarding the time during which we will be an emerging growth company under the Jumpstart Our Business Startups Act (“JOBS Act”);

•our future capital requirements and sources and uses of cash;

•our ability to obtain funding for our operations;

•our business, expansion plans and opportunities;

•our relationships with third-parties, including our suppliers;

•issues related to the shipment and installation of our products;

•issues related to customer acceptance of our products;

•the outcome of any known and unknown litigation and regulatory proceedings;

•our ability to successfully deploy the proceeds from the Business Combination (as defined herein); and

•other risks and uncertainties discussed in “Item 1A. Risk Factors” and elsewhere in this Quarterly Report on Form 10-Q.

The forward-looking statements contained in this report are based on our current expectations and beliefs concerning future developments and their potential effects on us. There can be no assurance that future developments affecting us will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond our control) and other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to, those factors described in “Item 1A. Risk Factors.” Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws. These risks and others described in “Item 1A. Risk Factors” may not be exhaustive.

By their nature, forward-looking statements involve risks and uncertainties because they relate to events and depend on circumstances that may or may not occur in the future. We caution you that forward-looking statements are not guarantees

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of future performance and that our actual results of operations, financial condition and liquidity, and developments in the industry in which we operate may differ materially from those made in or suggested by the forward-looking statements contained in this report. In addition, even if our results or operations, financial condition and liquidity, and developments in the industry in which we operate are consistent with the forward-looking statements contained in this report, those results or developments may not be indicative of results or developments in subsequent periods.

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PART I – FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

ESS Tech, Inc.

Consolidated Balance Sheets

(Unaudited, in thousands, except share and per share data)

	March 31, 2022		December 31, 2021
ASSETS
Current assets:
Cash and cash equivalents	$	212,331	$	238,940
Restricted cash, current	1,167		1,217
Accounts receivable, net	2,928		517
Prepaid expenses and other current assets	4,406		4,844
Total current assets	220,832		245,518
Property and equipment, net	10,056		4,501
Operating lease right-of-use assets	4,260		—
Restricted cash, non-current	75		75
Other non-current assets	261		105
Total assets	$	235,484	$	250,199
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	1,745	$	1,572
Accrued and other current liabilities	6,615		6,487
Operating lease liabilities, current	1,310		—
Deferred revenue	6,859		3,663
Notes payable, current	1,817		1,900
Total current liabilities	18,346		13,622
Notes payable, non-current	1,483		1,869
Operating lease liabilities, non-current	3,612		—
Earnout warrant liabilities	636		1,476
Public warrant liabilities	8,042		18,666
Private warrant liabilities	3,815		8,855
Other non-current liabilities	101		552
Total liabilities	36,035		45,040
Commitments and contingencies (Note 10)
Stockholders’ equity:
Preferred stock ($0.0001 par value; 200,000,000 shares authorized, none issued and outstanding as of March 31, 2022 and December 31, 2021)	—		—
Common stock ($0.0001 par value; 2,000,000,000 shares authorized, 152,606,563 and 151,839,058 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively)	16		16
Additional paid-in capital	745,752		745,753
Accumulated deficit	(546,319)		(540,610)
Total stockholders' equity	199,449		205,159
Total liabilities and stockholders’ equity	$	235,484	$	250,199

See accompanying notes to consolidated financial statements

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ESS Tech, Inc.

Consolidated Statements of Operations and Comprehensive Loss

(Unaudited, in thousands, except share and per share data)

	Three Months Ended March 31,
	2022		2021
Operating expenses:
Research and development	$	12,898	$	5,652
Sales and marketing	1,501		512
General and administrative	7,789		2,120
Total operating expenses	22,188		8,284
Loss from operations	(22,188)		(8,284)
Other income (expenses), net:
Interest expense, net	(29)		(57)
Gain (loss) on revaluation of warrant liabilities	15,664		(8,426)
Loss on revaluation of derivative liabilities	—		(138,141)
Gain on revaluation of earnout liabilities	840		—
Other income (expense), net	4		(10)
Total other income (expenses), net	16,479		(146,634)
Net loss and comprehensive loss to common stockholders	$	(5,709)	$	(154,918)
Net loss per share - basic and diluted	$	(0.04)	$	(2.51)
Weighted average shares used in per share calculation - basic and diluted	151,683,819		61,693,067

See accompanying notes to consolidated financial statements

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ESS Tech, Inc.

Consolidated Statements of Stockholders’ Equity (Deficit)

(Unaudited, in thousands, except share and per share data)

	Redeemable Convertible Preferred Stock			Common Stock			Common Stock Warrants		Additional Paid-In Capital		Accumulated Deficit		Total Stockholders' Equity (Deficit)
	Shares	Amount		Shares	Amount
Balance as of December 31, 2020	—	$	—	58,919,345	$	6	$	153	$	35,446	$	(63,493)	$	(27,888)
Issuance of Legacy ESS Redeemable Convertible Preferred Stock	—	—		5,746,003	1		—		29,515		—		29,516
Issuance of common stock upon exercise of options	—	—		2,379,260	—		—		518		—		518
Issuance of common stock upon exercise of warrants	—	—		60,418	—		—		356		—		356
Stock-based compensation expense	—	—		—	—		—		129		—		129
Net loss	—	—		—	—		—		—		(154,918)		(154,918)
Balance as of March 31, 2021	—	$	—	67,105,026	$	7	$	153	$	65,964	$	(218,411)	$	(152,287)
Balance as of December 31, 2021	—	$	—	151,839,058	$	16	$	—	$	745,753	$	(540,610)	$	205,159
Issuance of common stock upon exercise of options	—	—		138,617	—		—		47		—		47
Issuance of common stock upon release of restricted stock units	—	—		873,070	—		—		—		—		—
Cancellation of shares used to settle payroll tax withholding	—	—		(244,202)	—		—		(2,808)		—		(2,808)
Warrants exercised	—	—		20	—		—		—		—		—
Stock-based compensation expense	—	—		—	—		—		2,760		—		2,760
Net loss	—	—		—	—		—		—		(5,709)		(5,709)
Balance as of March 31, 2022	—	$	—	152,606,563	$	16	$	—	$	745,752	$	(546,319)	$	199,449

See accompanying notes to consolidated financial statements

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ESS Tech, Inc.

Consolidated Statements of Cash Flows

(Unaudited, in thousands)

	Three Months Ended March 31,
	2022		2021
Cash flows from operating activities:
Net loss	$	(5,709)	$	(154,918)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	196		130
Non-cash interest expense	14		21
Non-cash lease expense	275		—
Stock-based compensation expense	2,760		129
Change in fair value of warrant liabilities	(15,664)		8,426
Change in fair value of derivative liabilities	—		138,141
Change in earnout liabilities	(840)		—
Changes in operating assets and liabilities:
Accounts receivable	785		—
Prepaid expenses and other assets	405		(294)
Accounts payable and other accrued liabilities	(1,596)		1,882
Net cash used in operating activities	(19,374)		(6,483)
Cash flows from investing activities:
Purchases of property and equipment	(4,041)		(133)
Net cash used in investing activities	(4,041)		(133)
Cash flows from financing activities:
Principal payments on notes payable	(483)		(101)
Proceeds from stock options exercised	47		518
Repurchase of shares from employees for income tax withholding purposes	(2,808)		—
Proceeds from sale of Legacy ESS Series C-2 redeemable convertible preferred stock, net of issuance costs	—		11,461
Net cash (used in) provided by financing activities	(3,244)		11,878
Net change in cash, cash equivalents and restricted cash	(26,659)		5,262
Cash, cash equivalents and restricted cash, beginning of period	240,232		6,394
Cash, cash equivalents and restricted cash, end of period	$	213,573	$	11,656

See accompanying notes to consolidated financial statements

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ESS Tech, Inc.

Statements of Cash Flows (continued)

(Unaudited, in thousands)

	Three Months Ended March 31,
	2022		2021
Supplemental disclosures of cash flow information:
Cash paid for operating leases included in cash used in operating activities	$	403	$	—
Non-cash investing and financing transactions:
Purchase of property and equipment included in accounts payable and accrued and other current liabilities	2,235		22
Right-of-use operating lease assets obtained in exchange for lease obligations	4,534		—
Right-of-use finance lease assets obtained in exchange for lease obligations	123		—
Extinguishment of derivative liabilities upon sale of Legacy ESS Series C-2 redeemable convertible preferred stock, net of amount allocated to warrants	—		18,055
Extinguishment of warrant liabilities upon exercise of Legacy ESS Series B, Series C-1 and Series C-2 redeemable convertible preferred stock warrants	—		356
Cash and cash equivalents	$	212,331	$	10,163
Restricted cash, current	1,167		1,167
Restricted cash, non-current	75		326
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$	213,573	$	11,656

See accompanying notes to consolidated financial statements

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ESS TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

1.DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION

Description of Business—ESS Tech, Inc. (“ESS” or the “Company”) is a long-duration energy storage company specializing in iron flow battery technology. ESS develops long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring four or more hours of flexible energy capacity. The Company’s products are designed for a 25-year operating life without performance degradation, and with minimal annual operational and maintenance requirements. The Company is in the research and development phase. Its products are still being developed and do not yet meet standard specifications to be sold commercially (“Commercially Available”).

The Company was originally incorporated as a Cayman Islands exempted company on July 21, 2020 as a publicly traded special purpose acquisition company under the name ACON S2 Acquisition Corp. (“STWO”) for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination involving STWO and one or more businesses. On October 8, 2021 (the “Closing Date”), the Company consummated the merger agreement (the “Merger Agreement”) dated May 6, 2021, by and among STWO, SCharge Merger Sub, Inc., a Delaware corporation and wholly owned direct subsidiary of STWO (“Merger Sub”), and ESS Tech, Inc., a Delaware corporation (“Legacy ESS”) following the approval at a special meeting of the stockholders of STWO held on October 5, 2021.

Pursuant to the terms of the Merger Agreement, STWO deregistered by way of continuation under the Cayman Islands Companies Act (2021 Revision) and registered as a corporation in the State of Delaware under Part XII of the Delaware General Corporation Law (the “Domestication”), and a business combination between STWO and Legacy ESS was effected through the merger of Merger Sub with and into Legacy ESS, with Legacy ESS surviving as a wholly owned subsidiary of STWO (together with the other transactions described in the Merger Agreement, the “Business Combination”). On the Closing Date, STWO changed its name from “ACON S2 Acquisition Corp” to “ESS Tech, Inc.”, and its common shares of stock and warrants for shares of ESS common stock commenced trading on the New York Stock Exchange under the new ticker symbols “GWH” and “GWH.W”, respectively.

Basis of Presentation—The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Pursuant to the Merger Agreement, the merger between Merger Sub and Legacy ESS was accounted for as a reverse recapitalization in accordance with U.S. GAAP (the “Reverse Recapitalization”). Under this method of accounting, STWO was treated as the “acquired” company and Legacy ESS was treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Reverse Recapitalization was treated as the equivalent of Legacy ESS issuing stock for the net assets of STWO, accompanied by a recapitalization. The net assets of STWO were stated at historical cost, with no goodwill or other intangible assets recorded. Legacy ESS was determined to be the accounting acquirer based on the following predominant factors:

•Legacy ESS’s existing stockholders had the greatest voting interest in the Company;

•Legacy ESS’s directors represented all of the new board of directors of the Company;

•Legacy ESS’s senior management continued as the senior management of the Company; and,

•Legacy ESS had the larger employee base.

The assets, liabilities and results of operations prior to the Reverse Recapitalization are those of Legacy ESS. The shares and corresponding capital amounts and losses per share, prior to the Reverse Recapitalization, have been retroactively restated based on shares reflecting the exchange ratio of approximately 1.47 (the “Per Share Consideration”) established in the Business Combination.

Unaudited Interim Financial Statements—The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. GAAP for interim financial information and in accordance with the rules and regulations of the SEC. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The unaudited consolidated financial statements reflect all normal and recurring adjustments that are, in the opinion of the Company’s management, necessary in order to make the consolidated financial statements not misleading. Operating results for the three months ended March 31, 2022 are not necessarily indicative of the results that may be expected for the year ending December 31, 2022. These unaudited interim consolidated financial statements should be read in conjunction with the consolidated financial statements and related

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notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021, as filed with the SEC on March 4, 2022.

Reclassifications—Certain prior year amounts have been reclassified to conform with current year presentation.

2.SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates—The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Such estimates relate to, among others, the useful lives and assessment of recoverability of property and equipment, deferred tax assets valuation, determination of the fair value of the Company’s earnout warrant liabilities and private warrants, as well as other accruals. These estimates are based on historical trends, market pricing, current events and other relevant assumptions and data points. Actual results could differ from those estimates and such differences may be material to the consolidated financial statements.

Net Loss Per Share—The Company follows the two-class method when computing net income (loss) per common share when shares are issued that meet the definition of participating securities. Under this method, net earnings are reduced by the amount of dividends declared in the current period for common shareholders and participating security holders. The remaining earnings or “undistributed earnings” are allocated between common stock and participating securities to the extent that each security may share in earnings as if all the earnings for the period had been distributed. Once calculated, the earnings per common share is computed by dividing the net income (loss) attributable to common shareholders by the weighted average number of common shares outstanding during each year presented. Diluted income (loss) attributable to common shareholders per common share has been computed by dividing the net income (loss) attributable to common shareholders by the weighted average number of common shares outstanding plus the dilutive effect of outstanding options, warrants, and restricted stock units (“RSU”) during the respective periods computed using the treasury method. In cases where the Company has a net loss, no dilutive effect is shown as options, warrants, RSU, and earnout shares pending satisfaction of a regulatory holding period become anti-dilutive.

Cash and Cash Equivalents—The Company considers all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents. Cash equivalents are recorded at carrying value, which approximates fair value. Cash and cash equivalents include cash in bank accounts and money market funds.

Restricted Cash—Restricted cash is required as collateral for certain of the Company’s lease agreements and contractual supply and service arrangements. Restricted cash includes a certificate of deposit for the Company’s lease agreements and a performance and payment bond for the Company’s supply and service arrangements. The certificate of deposit and bond are recorded at carrying value, which approximates fair value. Restricted cash amounts are reported in the consolidated balance sheets as current or non-current depending on when the cash will be contractually released.

Revenue Recognition—The Company did not recognize any revenue in either of the three month periods ended March 31, 2022 or 2021. The Company will recognize revenue in accordance with the requirements of, and the guidance provided by Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers (Topic 606).

Stock-Based Compensation—The Company accounts for stock-based compensation in accordance with ASC 718, Compensation – Stock Compensation. The Company measures and recognizes compensation expense for all stock-based awards based on estimated fair values on the date of the grant, recognized over the requisite service period. For awards that vest solely based on a service condition, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period. The compensation expense related to awards with performance conditions is recognized over the requisite service period when the performance conditions are probable of being achieved. The compensation expense related to awards with market conditions is recognized on an accelerated attribution basis over the requisite service period identified as the derived service period over which the market conditions are expected to be achieved, and is not reversed if the market condition is not satisfied. The Company accounts for forfeitures as they occur. Stock-based awards granted to employees are primarily stock options and RSUs.

The fair value of each stock option granted is estimated using the Black-Scholes Merton option-pricing model using the single-option award approach. The following assumptions are used in the Black-Scholes Merton option-pricing model:

Risk-Free Interest Rate—The risk-free interest rate is based on the implied yield available on the date of grant on U.S. Treasury zero-coupon issued with a term that is equal to the option’s expected term at the grant date.

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Expected Volatility—The Company estimates the volatility for option grants by evaluating the average historical volatility of a peer group of companies for the period immediately preceding the option grant for a term that is approximately equal to the option’s expected term.

Expected Term—The expected term for employees represents the period over which options granted are expected to be outstanding using the simplified method, as the Company’s historical share option exercise experience does not provide a reasonable basis upon which to estimate the expected term. The simplified method deems the term to be the average of the time-to-vesting and contractual life of the stock-based awards.

Dividend Yield—The Company has not declared or paid dividends to date and does not anticipate declaring dividends. As such, the dividend yield has been estimated to be zero.

Fair Value—The Company follows ASC 820, Fair Value Measurements (“ASC 820”), which establishes a common definition of fair value to be applied when U.S. GAAP requires the use of fair value, establishes a framework for measuring fair value, and requires certain disclosure about such fair value measurements.

ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about what market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs as follows:

Level 1: Observable inputs such as quoted prices in active markets for identical assets or liabilities to which the Company has access at a measurement date.

Level 2: Observable inputs other than Level 1 quoted prices that are observable for the asset or liability, either directly or indirectly; these include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3: Unobservable inputs for which little or no market data exists and for which the Company must develop its own assumptions regarding the assumptions that market participants would use in pricing the asset or liability, including assumptions regarding risk.

Because of the uncertainties inherent in the valuation of assets or liabilities for which there are no observable inputs, those estimated fair values may differ significantly from the values that may have been used had a ready market for the assets or liabilities existed.

Recent Accounting Pronouncements—Pursuant to the Jumpstart Our Business Startups Act (“JOBS Act”), an emerging growth company is provided the option to adopt new or revised accounting standards that may be issued by the FASB or the SEC either (i) within the same periods as those otherwise applicable to non-emerging growth companies or (ii) within the same time periods as private companies. The Company has elected to use the extended transition period for complying with any new or revised financial accounting standards. As a result, the Company’s consolidated financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective date for new or revised accounting standards that are applicable to public companies. The Company also intends to continue to take advantage of some of the reduced regulatory and reporting requirements of emerging growth companies pursuant to the JOBS Act so long as the Company qualifies as an emerging growth company.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with a forward-looking expected credit loss model, which will result in earlier recognition of credit losses. ASU 2016-13 is effective for emerging growth companies for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The Company is currently evaluating the impact that the standard will have on its consolidated financial statements and related disclosures.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes. ASU 2019-12 is effective for emerging growth companies for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. The Company is currently evaluating the impact that the standard will have on its consolidated financial statements and related disclosures.

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Recently Adopted Accounting Pronouncements—On January 1, 2022, the Company adopted ASU 2016-02, Leases (ASC 842), which superseded previous guidance related to accounting for leases within Topic 840, Leases. The Company elected the practical expedient provided under ASU 2018-11, Leases (Topic 842) Targeted Improvements, which amended ASU 2016-02 to provide entities an optional transition practical expedient to adopt the new standard with a cumulative effect adjustment as of the beginning of the year of adoption with prior year comparative financial information and disclosures remaining as previously reported. As a result, no adjustments were made to the consolidated balance sheet prior to January 1, 2022 and amounts are reported in accordance with historical accounting under Topic 840, while the consolidated balance sheet as of March 31, 2022 is presented under Topic 842.

The Company elected the package of practical expedients permitted under the transition guidance, which allowed it to carry forward historical lease classification, assessment on whether a contract was or contains a lease, and assessment of initial direct costs for any leases that existed prior to January 1, 2022. The Company also elected to combine its lease and non-lease components and to keep leases with an initial term of 12 months or less off the consolidated balance sheet and recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term.

For new required disclosures and further information see Note 8, Leases. Adoption of the new standard resulted in the recording of lease assets and lease liabilities of $4,534 thousand and $5,229 thousand, respectively, as of January 1, 2022. The transition did not have a material impact on the Company’s results of operations, cash flows or liquidity measures.

3.BUSINESS COMBINATION

As discussed in Note 1, on October 8, 2021, the Company consummated the Business Combination pursuant to the Merger Agreement, with Legacy ESS surviving the Business Combination as a wholly owned subsidiary of the Company. Upon the Business Combination closing (the “Closing”), each share of Legacy ESS’s common stock, par value $0.0001 per share (“Legacy ESS Common Stock”) and Preferred Stock, par value $0.0001 per share (“Legacy ESS Preferred Stock”), were converted into the right to receive shares of the Company’s common stock at the Per Share Consideration as calculated pursuant to the Merger Agreement. The aggregate consideration paid to Legacy ESS stockholders in connection with the Business Combination (excluding any potential Earnout Shares (see below for definition)), was 99,700,326 shares of the Company’s common stock (including 125,958 shares of common stock issued following the Closing as a result of a transaction expense adjustment as disclosed in the Company’s Form 8-K filed with the SEC on November 15, 2021).

Pursuant to the Merger Agreement, the Company was permitted to issue to eligible Legacy ESS securityholders, on a pro rata basis, up to 16,500,000 shares of additional common stock (the “Earnout Shares”) less any RSUs issued pursuant to the Incentive RSU Pool, issuable in two equal tranches upon the occurrence of the respective Earnout Milestone Events. The Earnout Milestone Events were achieved on November 9, 2021 and Legacy ESS issued 15,674,965 shares to securityholders.

Upon the closing of the Business Combination, the Company's certificate of incorporation was amended and restated to, among other things, increase the total number of authorized shares of capital stock to 2,200,000,000, of which 2,000,000,000 shares are Common Stock, $0.0001 par value per share, and 200,000,000 shares are Preferred Stock, $0.0001 value per share.

4.NET LOSS PER SHARE

The following table presents the calculation of basic and diluted net loss per share attributable to common stockholders (in thousands, except per share data):

	Three Months Ended March 31,
	2022		2021
Net loss attributable to common stockholders	$	(5,709)	$	(154,918)
Weighted-average shares outstanding – Basic and Diluted	151,683,819		61,693,067
Net loss per share – Basic and Diluted	$	(0.04)	$	(2.51)

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Due to the net losses for the three months ended March 31, 2022 and 2021, basic and diluted net loss per common share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

The following outstanding balances of common share equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented:

	March 31, 2022	March 31, 2021
Stock options	3,707,113	4,379,633
RSUs	4,633,968	—
Warrants	11,461,227	3,362,047
Number of securities outstanding	19,802,308	7,741,680

5.PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Insurance	$	2,397	$	3,482
Vendor advances	1,514		1,103
Other	495		259
Total prepaid expenses and other current assets	$	4,406	$	4,844

6.PROPERTY AND EQUIPMENT, NET

Property and equipment, net consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Machinery and equipment	$	2,910	$	2,868
Furniture and fixtures	88		90
Leasehold improvements	1,030		746
Construction in process	7,944		2,517
Total property and equipment	11,972		6,221
Less accumulated depreciation	(1,916)		(1,720)
Total property and equipment, net	$	10,056	$	4,501

Depreciation and amortization expense related to property and equipment, net was $196 thousand and $130 thousand for the three months ended March 31, 2022 and 2021, respectively.

7.ACCRUED AND OTHER CURRENT LIABILITIES

Accrued and other current liabilities consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Payroll and related benefits	$	1,552	$	1,876
Materials and related purchases	2,596		2,108
Deferred rent	—		142
Professional and consulting fees	1,140		1,820
Other	1,327		541
Total accrued and other current liabilities	$	6,615	$	6,487

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8.LEASES

The Company determines if an arrangement is a lease at inception and whether the arrangement is classified as an operating or finance lease. At commencement of the lease, the Company records a right-of-use (“ROU”) asset and lease liability in the consolidated balance sheets based on the present value of lease payments over the term of the arrangement. ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. As the Company’s leases do not provide an implicit rate, it uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The Company determines its incremental borrowing rate based on publicly available data for instruments with similar characteristics, including recently issued debt, as well as other factors. Contract terms may include options to extend or terminate the lease, and when the Company deems it reasonably certain that ESS will exercise that option it is included in the ROU asset and lease liability. Operating leases will reflect lease expense on a straight-line basis, while finance leases will result in the separate presentation of interest expense on the lease liability and amortization expense of the ROU asset.

ROU assets related to the Company’s operating leases are included in operating lease ROU assets, while the corresponding lease liabilities are included in current and non-current operating lease liabilities on our consolidated balance sheets. ROU assets related to the Company’s finance leases are included in other non-current assets, while the corresponding lease liabilities are included in accrued and other current liabilities and other non-current liabilities on the Company’s consolidated balance sheets.

The Company does not record leases with a term of 12-months or less in the consolidated balance sheets. There was no short-term lease cost for the three months ended March 31, 2022.

The Company leases office and manufacturing space in Wilsonville, Oregon under operating leases and printers and copiers under finance leases. Each of the operating leases provides the Company an option to renew the lease for an additional 60 months which have not been included in the operating lease obligations.

Operating lease costs for the three months ended March 31, 2022 were $371 thousand. As of March 31, 2022, the weighted-average remaining term for the operating leases was 3.4 years and the weighted-average discount rate was 7.5%. The weighted-average remaining term for the finance lease was 4.9 years and the weighted-average discount rate was 7.5%.

As of March 31, 2022 future maturities of lease liabilities are as follows (in thousands):

	Operating Leases		Finance Leases
2022	$	1,222	$	21
2023	1,670		30
2024	1,720		30
2025	983		30
2026	—		30
Thereafter	—		7
Total minimum lease payments	$	5,595	$	148
Less imputed interest	(673)		(25)
Total	$	4,922	$	123

9.BORROWINGS

Long term debt consists of the following (in thousands):

	March 31, 2022		December 31, 2021
Total notes payable	$	3,300	$	3,769
Less current portion of notes payable	1,817		1,900
Notes payable, non-current	$	1,483	$	1,869

Notes Payable

In 2018, the Company entered into a $1,000 thousand note payable with a bank that was secured by all property of the Company, except for its intellectual property. The note payable’s original maturity date was July 1, 2021.

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In March 2020, the Company amended the note payable and borrowed an additional $4,000 thousand. The additional $4,000 thousand borrowing changed the present value of cash flows by more than 10% and, as such, was treated as a debt extinguishment. The Company recognized a $62 thousand loss on extinguishment of debt for the year ended December 31, 2021. The Company’s notes payable to the bank were recorded at fair value as part of the extinguishment. The $4,000 thousand note payable’s original maturity date was January 1, 2023.

In April 2020, the Company entered into a deferral agreement (“Deferral Agreement”) to extend the maturity date of the original $1,000 thousand note payable to September 1, 2022 and extend the maturity date of the additional $4,000 thousand note payable to January 1, 2024. The Company accounted for the Deferral Agreement as a debt modification based on an analysis of cash flows before and after the debt modification.

The notes payable bear interest at 0.50% below the bank’s prime rate (3.00% on March 31, 2022). The Company makes monthly interest and principal payments on the note payable based on the schedule defined in the agreement.

10.COMMITMENTS AND CONTINGENCIES

The Company, from time to time, is a party to various claims, legal actions, and complaints arising in the ordinary course of business. The Company is not aware of any legal proceedings or other claims, legal actions, or complaints through the date of issuance of these consolidated financial statements.

As of March 31, 2022, and December 31, 2021, the Company had a standby letter of credit with First Republic Bank totaling $725 thousand as security for an operating lease of office and manufacturing space in Wilsonville, Oregon. As of March 31, 2022 the letter of credit was secured by a restricted certificate of deposit account totaling $75 thousand. There were no draws against the letter of credit during the three months ended March 31, 2022 and 2021.

The Company purchases materials from several suppliers and has entered into agreements with various contract manufacturers, which include cancellable and noncancellable purchase commitments.

As of March 31, 2022 and December 31, 2021, total unfulfilled noncancellable purchase commitments were $23,344 thousand and $10,160 thousand, respectively. In addition, total unfulfilled cancellable purchase commitments amounted to $3,539 thousand and $10,446 thousand as of March 31, 2022, and December 31, 2021, respectively. These purchase commitments were not recorded in the consolidated financial statements.

11.LEGACY ESS REDEEMABLE CONVERTIBLE PREFERRED STOCK

All Legacy ESS redeemable convertible preferred stock classified as redeemable was converted into Legacy ESS common stock, which was subsequently exchanged for the Company’s common stock as a result of the Business Combination using the Per Share Consideration of approximately 1.47. All preferred stock amounts have been retroactively adjusted to reflect the Business Combination.

Immediately prior to the completion of the Business Combination on October 8, 2021, all outstanding shares of Legacy ESS’s redeemable convertible preferred stock converted into an aggregate 57,104,332 shares of common stock.

Legacy ESS Rights to Purchase Series C-2 Convertible Preferred Stock

Legacy ESS’s Series C redeemable convertible preferred stock financing agreement initially provided additional committed funding of up to $79,999 thousand, through the purchase of up to 39,971,716 shares of Series C-2 redeemable convertible preferred stock based on the completion of certain operational milestones at a predetermined price of $2.00 per share, to certain Series C-1 Investors.

Legacy ESS determined that its obligation to issue, and Legacy ESS’s investors’ obligation to purchase shares of Series C-2 redeemable convertible preferred stock at a fixed price represents a freestanding derivative financial instrument (the “Series C-2 Redeemable Convertible Preferred Stock Issuance Right”). The Series C-2 Redeemable Convertible Preferred Stock Issuance Right was initially recorded at fair value and was adjusted to fair value at each reporting date, with the change in fair value recorded as a revaluation of derivative liabilities as a component of other income and expense in the consolidated statement of operations. The Series C-2 Redeemable Convertible Preferred Stock Issuance Right was initially scheduled to expire in August 2021 and was classified as a non-current derivative liability as of March 31, 2021.

The Series C-2 Redeemable Convertible Preferred Stock Issuance Right was initially valued at a fair value of $11,379 thousand.

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Sale of Legacy ESS Series C-2 Redeemable Convertible Preferred Stock

In March 2021, Legacy ESS issued 5,746,003 shares of Series C-2 redeemable convertible preferred stock for $2.00 per share, totaling $11,500 thousand. Legacy ESS incurred $39 thousand in costs associated with the issuance. In connection with the sale of the Series C-2 redeemable convertible preferred stock, Legacy ESS issued warrants to purchase 861,896 shares of Series C-2 redeemable convertible preferred stock and extinguished a portion of the C-2 Purchase Right for 5,746,003 shares. The warrants were exercisable at a price of $0.0001 per share. The extinguishment of a portion of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right reduced Legacy ESS’s derivative liabilities and increased the amount attributable to the issuance by $23,152 thousand. Total transaction value of $34,613 thousand was allocated to the Series C-2 redeemable convertible preferred stock and warrants in the amounts of $29,516 thousand and $5,096 thousand, respectively.

Amendment to Legacy ESS Series C-2 Redeemable Convertible Preferred Stock Purchase Right and Related Warrants

On May 7, 2021, Legacy ESS amended its Series C-2 Preferred Stock Purchase Agreement and Amendment to Series C Preferred Stock Purchase Agreement. Under the terms of the amended agreement, the number of shares of C-2 Convertible Redeemable Preferred Stock required to be issued by Legacy ESS and purchased by investors under the C-2 Redeemable Convertible Preferred Stock Purchase Right were adjusted, and Legacy ESS issued Series C-2 warrants. The Series C-2 warrants were exercisable at a price of $.00007 per share upon a successful Business Combination with STWO. The investors were permitted to purchase shares subject to the C-2 Redeemable Convertible Preferred Stock Purchase Right at any time and must purchase the shares upon the Company’s achievement of specific milestones. The number of shares subject to and potential proceeds from the C-2 Redeemable Convertible Preferred Stock Purchase Agreement and related C-2 Warrants were as follows:

	As of May 7, 2021
	Upon completion of the Business Combination
	Quantity	Price
Series C-2 Redeemable Convertible Preferred Stock Purchase Right	7,994,442	$	2.00
Series C-2 Warrant exercisable upon completion of the Business Combination	21,159,364	$	0.00007

The C-2 warrants and Purchase Rights were exercised in conjunction with the Business Combination which closed on October 8, 2021 and the Company received proceeds of $15,559 thousand, which were net of $439 thousand in issuance costs.

The Company recorded a net increase in the derivative liability of $138,141 thousand for the three months ended March 31, 2021 for changes in the estimated fair value of the Series C-2 Redeemable Convertible Preferred Stock Purchase Right and C-2 Warrant exercisable upon completion of the Business Combination.

Legacy ESS Warrants

Legacy ESS Series B redeemable convertible preferred stock warrants were issued at exercise prices ranging from $0.0007 per share to $0.83 per share. 100,161 shares of Series B redeemable convertible preferred stock warrants had a 10-year exercise period and the remainder did not expire until a significant transaction had occurred, as defined by the warrant purchase agreement. The warrants were fully vested at the issuance date.

Legacy ESS Series C-1 and C-2 redeemable convertible preferred stock warrants were issued with prices ranging from $0.00007 to $1.25 per share, a life of 10 years and were fully vested at issuance.

Legacy ESS common stock warrants, all issued at a price of $0.0007 per share, were recorded at fair value within equity. Legacy ESS common stock warrants were fully vested at issuance and did not expire until a significant transaction has occurred, as defined by the Warrant Purchase Agreement.

In connection with the Business Combination, all Legacy ESS warrants were exercised during the year ended December 31, 2021.

12.COMMON STOCK WARRANTS

As of March 31, 2022, the Company had 7,377,893 warrants to purchase common stock listed on the New York Stock Exchange (“NYSE”) under the ticker symbol “GWH.W” (the “Public Warrants”), 3,500,000 warrants to purchase

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common stock issued in a private placement concurrently with STWO’s initial public offering (the “Private Warrants”) and 583,334 Earnout Warrants (as defined below) outstanding.

As part of STWO’s initial public offering, 8,333,287 Public Warrants were sold. The Public Warrants entitle the holder thereof to purchase one share of common stock at a price of $11.50 per share, subject to adjustments. The Public Warrants may be exercised only for a whole number of shares of common stock. No fractional shares will be issued upon exercise of the warrants. The Public Warrants will expire five years after completion of the business combination, on October 8, 2026, or earlier upon redemption or liquidation.

The Company may call the Public Warrants for redemption starting anytime, in whole and not in part, at a price of $0.01 per warrant, so long as the Company provides not less than 30 days prior written notice of redemption to each warrant holder, and if, and only if, the reported last sale price of common stock equals or exceeds $18.00 per share or $10.00 per share for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date the Company sends the notice of redemption to the warrant holders provided there is an effective registration statement covering the shares of common stock issuable upon exercise of the warrants.

The Company may call the Public Warrants for redemption starting anytime, in whole and not in part, at a price of $0.10 per warrant, so long as the Company provides not less than 30 days prior written notice of redemption to each warrant holder; provided that holders will be able to exercise their warrants on a cashless basis prior to redemption and receive a number of shares determined based on the redemption date fair market value of the shares, and if, and only if, the reported last sale price of common stock equals or exceeds $10.00 per share or $10.00 per share for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date the Company sends the notice of redemption to the warrant holders provided there is an effective registration statement covering the shares of common stock issuable upon exercise of the warrants.

Simultaneously with STWO’s initial public offering, STWO consummated a private placement of 4,666,667 Private Warrants with STWO’s sponsor. In connection with the Business Combination, STWO’s sponsor agreed to forfeit 583,333 Private Warrants. Of the remaining 4,083,334 Private Warrants, 3,500,000 were immediately vested and 583,334 warrants (the “Earnout Warrants”) were vested upon meeting certain Earnout Milestone Events on November 9, 2021. Each Private Warrant and Earnout Warrant is exercisable for one share of common stock at a price of $11.50 per share, subject to adjustment.

The Private Warrants and Earnout Warrants, post vesting on November 9, 2021, are identical to the Public Warrants, except that the Private Warrants and Earnout Warrants and the shares of common stock issuable upon exercise of the Private Warrants are not transferable, assignable or salable until 30 days after the completion of a Business Combination, subject to certain limited exceptions. Additionally, the Private Warrants and Earnout Warrants are non-redeemable so long as they are held by the initial purchasers or such purchasers’ permitted transferees. If the Private Warrants and Earnout Warrants are held by someone other than their initial purchasers or their permitted transferees, then the Private Warrants and Earnout Warrants will be redeemable by the Company and exercisable by such holders on the same basis as the Public Warrants. Additionally, if the Company redeems the Public Warrants when the common stock equals or exceeds $10.00 per share for any 20 trading days within a 30-day period ending on the third trading day prior to the date the Company sends the notice of redemption to warrant holders and the closing price of the common share for any 20 trading days within the same period is less than $18.00 per share, the Company must concurrently redeem the Private Warrants and Earnout Warrants.

The table below shows the common stock warrant activities during the three months ended March 31, 2022:

	December 31, 2021	Issued	Exercised	March 31, 2022
Earnout Warrants	583,334	—	—	583,334
Public Warrants	7,377,913	—	20	7,377,893
Private Warrants	3,500,000	—	—	3,500,000
Total Common Stock Warrants	11,461,247	—	20	11,461,227

The Company’s common stock warrants were initially recorded at fair value upon completion of the Business Combination and are adjusted to fair value at each reporting date based on the market price of the Public Warrants, with the change in fair value recorded as a component of other income and expense in the consolidated statements of operations. For the three months ending March 31, 2022, the Company recorded a net decrease to the liabilities for Earnout Warrants, Public Warrants and Private Warrants of $840 thousand, $10,624 thousand and $5,040 thousand, respectively.

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13.STOCK-BASED COMPENSATION PLAN

2021 Equity Incentive Plan

In October 2021, the Board of Directors of the Company adopted the ESS Tech Inc. 2021 Equity Incentive Plan (the “2021 Plan”). The 2021 Plan became effective upon consummation of the Business Combination. The stock awards may be issued as Incentive Stock Options (“ISO”), Non-statutory Stock Options (“NSO”), Stock Appreciation Rights, Restricted Stock Awards, or Restricted Stock Unit Awards. Only employees are eligible to receive ISO awards. Employees, directors, and consultants who are providing continuous service to the Company are eligible to receive stock awards other than ISOs. The number of Shares available for issuance under the 2021 Plan will be increased on the first day of each fiscal year beginning with the 2022 fiscal year and ending with the 2031 Fiscal Year, in an amount equal to the lesser of (i) 15,260,000 Shares, (ii) five percent (5%) of the outstanding shares on the last day of the immediately preceding fiscal year, or (iii) such number of shares determined by the Company no later than the last day of the immediately preceding fiscal year. Under the 2021 Plan, the Company is authorized to issue 17,610,000 shares of common stock as of March 31, 2022.

Option prices for incentive stock options are set at the fair market value of the Company’s common stock at the date of grant. Employee new hire options generally cliff vest at the end of the first year and then 1/48th of the original grant over the remaining three years. Grants expire 10 years from the date of grant.

No ISOs, NSOs, Restricted Stock Awards, nor Stock Appreciation Rights were outstanding as of March 31, 2022.

Shares Available for Future Grant

As of March 31, 2022, there were 13,021,489 shares available for future grant under the 2021 Plan.

Stock option and RSU activity, prices, and values during the three months ended March 31, 2022 is as follows (in thousands, except for share, per share, and contractual term data):

	Options Outstanding						RSUs
	Number of shares	Weighted average exercise price		Weighted average remaining  contractual term (years)	Aggregate intrinsic values ($'000s)		Number of plan shares outstanding	Weighted average grant date fair value per Share
Balances as of December 31, 2021	3,796,530	$	0.83	8.08	$	40,274	3,392,153	$	10.69
Options and RSUs granted	65,717	8.00					2,150,859	5.46
Options exercised and RSUs released	(138,617)	0.30					(873,070)	11.12
Options and RSUs forfeited	(16,517)	0.36					(35,974)	10.15
Balances as of March 31, 2022	3,707,113	$	0.98	8.03	$	17,012	4,633,968	$	8.82
Options vested and exercisable - December 31, 2021	1,827,374	$	0.31	7.20	$	20,337
Options vested and exercisable - March 31, 2022	1,626,013	$	0.56	7.41	$	8,140

In accordance with ASC 718, Compensation – Stock Compensation, the fair value of each option grant has been estimated as of the date of grant using the following weighted average assumptions:

	Three Months Ended March 31,
	2022		2021
Risk-free rate	1.64	%	0.75	%
Expected dividends	—		—
Expected term	6 years		6 years
Expected volatility	73.95	%	74.80	%

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Stock-based compensation expense is allocated on a departmental basis, based on the classification of the award holder. The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended March 31,
	2022		2021
Research and development	$	587	$	64
Sales and marketing	54		16
General and administrative	2,119		49
Total stock-based compensation	$	2,760	$	129

As of March 31, 2022, there was approximately $24,071 thousand of unamortized stock-based compensation expense related to unvested stock options and RSUs, which was expected to be recognized over a weighted average period of 3.11 years.

14.FAIR VALUE MEASUREMENTS

The Company follows ASC 820, Fair Value Measurements, which establishes a common definition of fair value to be applied when U.S. GAAP requires the use of fair value, establishes a framework for measuring fair value, and requires certain disclosure about such fair value measurements. The following table presents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis (in thousands):

March 31, 2022	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents and restricted cash:
Money market funds	$	211,369	$	—	$	—	$	211,369
Certificate of deposit	—		75		—		75
Total assets	$	211,369	$	75	$	—	$	211,444
Liabilities:
Earnout warrant liabilities	$	—	$	636	$	—	$	636
Public common stock warrants	8,042		—		—		8,042
Private common stock warrants	—		3,815		—		3,815
Total liabilities	$	8,042	$	4,451	$	—	$	12,493

December 31, 2021	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents and restricted cash:
Money market funds	$	237,897	$	—	$	—	$	237,897
Certificate of deposit	—		125		—		125
Total assets	$	237,897	$	125	$	—	$	238,022
Liabilities:
Earnout warrant liabilities	$	—	$	1,476	$	—	$	1,476
Public common stock warrants	18,666		—		—		18,666
Private common stock warrants	—		8,855		—		8,855
Total liabilities	$	18,666	$	10,331	$	—	$	28,997

There were no transfers among Level 1, Level 2, or Level 3 categories during the periods presented. The carrying amounts of the Company’s notes payable, and accounts payable approximate their fair values due to their short maturities.

Level 1 Assets:

The Company invests in money market funds that have maturities of 90 days or less. Money market funds are classified as cash equivalents and are recorded at their carrying value, which approximates fair value.

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Level 2 Assets:

The Company invests in a certificate of deposit with a maturity of one year from purchase date. The certificate of deposit is classified as restricted cash and is recorded at its carrying value, which approximates fair value.

Level 1 Liabilities:

The Company values its public common stock warrants based on the market price of the warrant.

Level 2 Liabilities:

The Company values its earnout warrant liabilities and private common stock warrants based on the market price of the Company’s public common stock warrants.

Level 3 Liabilities:

Warrants

Freestanding warrants to purchase Redeemable Convertible Preferred Stock were accounted for as liability awards and recorded at fair value on their issuance date and adjusted to fair value at each reporting date, with the change in fair value being recorded as a component of other income (expenses), net. The warrants were accounted for as liabilities as the underlying shares of Preferred Stock were contingently redeemable upon occurrence of a change in control, which was outside the control of the Company.

As of March 31, 2021, the Company measured its warrant liabilities using Level 3 unobservable inputs within the Black-Scholes Merton option-pricing model. The Company used various key assumptions, such as the fair value of Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants, the volatility of peer companies’ stock prices, the risk-free interest rate based on the U.S. Treasury yield, and the expected term (based on remaining term to a significant event for Series B redeemable convertible preferred stock warrants and remaining contractual term for Series C redeemable convertible preferred stock warrants). The Company measured the fair value of the redeemable convertible Preferred Stock warrants at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded through other income (expenses), net in the consolidated statements of operations and comprehensive loss.

Future Rights to Purchase Series C-2 Redeemable Convertible Preferred Stock

See Note 11 for a discussion of the Company’s Series C Redeemable Convertible Preferred Stock financing agreement.

The value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right was determined based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy.

The fair value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right was determined using a discounted cash flow model, which takes into account the estimated value of Series C-2 stock, estimated time to purchase, probability of purchase and the risk-free interest rate based on the U.S. Treasury yield. The Company measures the fair value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded through other expense, net in the consolidated statements of operations and comprehensive loss.

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The following table sets forth a summary of changes in the fair value of the Company’s Level 3 liabilities at fair value on a recurring basis (in thousands):

	Three Months Ended March 31,
	2022		2021
Warrant liabilities:
Beginning balance December 31	$	—	$	3,329
Change in fair value	—		8,426
Fair value of warrants issued	—		5,096
Fair value of warrants exercised	—		(356)
Ending balance March 31	—		16,495
Series C-2 Convertible Preferred Stock Issuance Right liability:
Beginning balance December 31	—		22,911
Change in fair value	—		138,141
Fair value of derivatives extinguished	—		(23,152)
Ending balance March 31	—		137,900
Total	$	—	$	154,395

15.INCOME TAXES

The Company did not record a tax provision for the three months ended March 31, 2022 and 2021, respectively, due to the Company’s history of losses, and accordingly, has recorded a valuation allowance against substantially all of the Company’s net deferred tax assets. The Company provides for a valuation allowance when it is more likely than not that some portion of, or all of the Company’s deferred tax assets will not be realized.

16.RELATED PARTY TRANSACTIONS

In April 2021, the Company signed a framework agreement with one of its investors, SB Energy Global Holdings One Ltd (“SBE”), to supply energy storage products to SBE in support of its market activities. Under this agreement, the Company has made various commitments to meet SBE’s potential need for energy storage products and is obligated to reserve a certain percentage of manufacturing capacity to meet SBE’s future needs, subject to periodic reviews of its firm and anticipated orders. To date, no orders have been placed under the framework agreement.

Additionally, the Company entered into a preferred financing equity transaction with SBE and Breakthrough Energy Ventures, LLC as discussed in Note 11. These related parties were also issued 6,707,318 of the Earnout Shares discussed in Note 3.

As of December 31, 2021, the Company had recorded accounts receivable of $66 thousand and deferred revenue of $171 thousand for sales of Energy Warehouse products to related parties.

As of March 31, 2022, the Company had recorded deferred revenue of $237 thousand for sales of Energy Warehouse products to related parties.

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ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS.

The following discussion and analysis of our financial condition and results of operations should be read together with the unaudited consolidated financial statements and related notes included elsewhere in this Quarterly report on Form 10-Q. This discussion contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those discussed below. Factors that could cause or contribute to such differences include those identified below and those discussed in the section titled “Risk Factors” included elsewhere in this Quarterly Report on Form 10-Q.

Overview

ESS is a long-duration energy storage company specializing in iron flow battery technology. We design and produce long-duration batteries predominantly using earth-abundant materials that we expect can be cycled over 20,000 times without capacity fade. Because we designed our batteries to operate using an electrolyte of primarily salt, iron and water, they are non-toxic and substantially recyclable.

Our long-duration iron flow batteries are the product of nearly 50 years of scientific advancement. Our founders, Craig Evans and Dr. Julia Song, began advancing this technology in 2011 and formed ESS. Our team has significantly enhanced the technology, improved the round-trip efficiency and developed an innovative and patented solution to the hydroxide build-up problem that plagued previous researchers developing iron flow batteries. Our proprietary solution to eliminate the hydroxide formation is known as the Proton Pump, and it works by utilizing hydrogen generated by side reactions on the negative electrode. The Proton Pump converts the hydrogen back into protons in the positive electrolyte. This process eliminates the hydroxide and stabilizes the electrolytes’ pH levels. The Proton Pump is designed to allow the electrolyte to be used for over 20,000 cycles without any capacity fade.

Our batteries provide flexibility to grid operators and energy assurance for commercial and industrial customers. Our technology addresses energy delivery, duration and cycle-life in a single battery platform that compares favorably to lithium-ion batteries, the most widely deployed alternative technology. Using our iron flow battery technology, we are developing two products, each of which is able to provide reliable, safe, long-duration energy storage. Our first energy storage product, the Energy Warehouse, is our “behind-the-meter” solution (referring to solutions that are located on the customer’s premises, behind the service demarcation with the utility) that offers energy storage ranging from four to 12-hour duration. Our second, larger scale energy storage product, the Energy Center, is designed for “front-of-the-meter” (referring to solutions that are located outside the customer’s premises, typically operated by the utility or by third-party providers who sell energy into the grid, often known as independent power producers) deployments specifically for utility and large commercial and industrial consumers.

We began shipping our second-generation Energy Warehouses in the third quarter of 2021 and we are continuing to install, commission, and test such units. With each battery deployed, we will further our mission to accelerate the transition to a zero-carbon energy future with increased grid reliability.

The Business Combination

On October 8, 2021, ESS consummated the Business Combination. As a result, Legacy ESS merged with Merger Sub, with Legacy ESS surviving as a wholly owned subsidiary of STWO, which changed its name to “ESS Tech, Inc.” Refer to Note 3 - Business Combination to the unaudited consolidated financial statements included in this report for more information.

Key Factors and Trends Affecting our Business

We believe that our performance and future success depends on several factors that present significant opportunities for us but also pose risks and challenges, including those discussed below and in the section “Item 1A. Risk Factors” included elsewhere in this Quarterly Report on Form 10-Q.

We believe we have the opportunity to establish high margin unit economics when operating at scale. Our future performance will depend on our ability to deliver on these economies of scale with lower product costs to enable profitable growth. We believe our business model is positioned for scalability due to the ability to leverage the same product platform across our customer base. Significant improvements in manufacturing scale are expected to decrease the cost of materials and direct labor. However, in the near term, we expect our operating expenses to increase as we ramp up our research and development and manufacturing activities including with respect to our supply chain, parts and launch of our second-generation Energy Warehouses as well as higher general and administrative expenses related to operating as a public company. Achievement of margin targets and cash flow generation is dependent on finalizing development and manufacturing of Energy Centers.

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Our near- and medium-term revenue is expected to be generated from our second-generation Energy Warehouses. We believe our unique technology provides a compelling value proposition for favorable margins and unit economics in the energy storage industry in the future.

COVID-19

The rapid global spread of the COVID-19 pandemic since December 2019 has disrupted supply chains and affected production and sales across a range of industries, and continues to impact the United States and other countries throughout the world. There have already been multiple waves of the COVID-19 pandemic and COVID-19 cases continue to surge in certain areas of the world, including in certain countries that were initially successful at containing the virus. For example, there has been a recent surge in China and the resultant lock down has begun to adversely affect supply chains. The evolution of the disease, the extent of its economic impact and the results of steps taken and yet to be taken by governments and financial institutions are still unknown. Due to the number of variables involved, the significance and the duration of the pandemic’s financial impact are difficult to determine. The extent of the impact of COVID-19 on our operational and financial performance will depend on certain developments, including the duration and spread of the virus, and the impact on our customers, employees and vendors. The ultimate outcome of these matters is uncertain and, accordingly, the impact on our financial condition or results of operations is also uncertain. We have issued several force majeure notices to customers as a result of delays caused by COVID-19 and the impact of COVID-19 on such agreements, or the applicable agreements’ termination provisions, is uncertain and could result in the termination of such agreements.

Components of Results of Operations

As the Business Combination is accounted for as a reverse recapitalization, the operating results included in this discussion reflect the historical operating results of Legacy ESS prior to the Business Combination and the combined results of ESS following the closing of the Business Combination. The assets and liabilities of the Company are stated at their historical cost.

Revenue

We earn revenue from the sale of our energy storage products and from service contracts. Revenue recognition is deferred for each unit until written customer acceptance has been received, after system testing, or until we establish a history of successfully achieving customer acceptance for each customer. In the near term, as our products are new, this is likely to be a longer process than when our products are more mature and we have more history of customer acceptance.

Operating expenses

Research and development

Costs related to research and development consist of direct product development material costs and product development personnel-related expenses, depreciation charges, overhead related costs, consulting services and other direct expenses. Personnel-related expenses consist of salaries, benefits and stock-based compensation. We expect our research and development costs to increase for the foreseeable future as we continue to invest in research and development activities to achieve our product roadmap.

Sales and marketing

Sales and marketing expenses consist primarily of salaries, benefits and stock-based compensation for marketing and sales personnel and related support teams. To a lesser extent sales and marketing expenses also includes professional services costs, travel costs, and trade show sponsorships. We expect that our sales and marketing expenses will increase over time as we continue to hire additional personnel to scale our business.

General and administrative

General and administrative expenses consist of personnel-related expenses for our corporate, executive, finance, legal, and other administrative functions, as well as expenses for outside professional services and insurance costs. Personnel-related expenses consist of salaries, benefits and stock-based compensation. To a lesser extent, general and administrative expense includes depreciation and other allocated costs, such as facility-related expenses, and supplies. We expect our general and administrative expenses to increase for the foreseeable future as we scale headcount with the growth of our business, and as a result of operating as a public company, including compliance with the rules and regulations of the SEC, legal, audit, additional insurance expenses, investor relations activities, and other administrative and professional services.

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Other income (expenses), net

Interest expense, net

Interest expense consists primarily of interest on our notes payable. Interest income consists primarily of earned income on our cash equivalents and restricted cash. These amounts will vary based on our cash, cash equivalents and restricted cash balances, and with market rates.

Gain (loss) on revaluation of warrant liabilities

The gain (loss) on revaluation of warrant liabilities consists of periodic fair value adjustments related to Legacy ESS’ Series B and C warrants outstanding prior to the Business Combination and the Public Warrants and Private Placement Warrants subsequent to the Business Combination.

Loss on revaluation of derivative liabilities

The loss on revaluation of derivative liability consists of periodic fair value adjustments associated with our derivative liability for the Legacy ESS Series C-2 Convertible Preferred Stock issuance right liability and contingently issuable warrants prior to the Business Combination.

Gain on revaluation of earnout warrants

The loss on revaluation of earnout warrants consists of periodic fair value adjustments related to the Earnout Warrants issued in conjunction with the Business Combination.

Other income (expense), net

Other income and expense, net consists of various other income and expense items.

Results of Operations

The following table sets forth ESS’ operating results for the periods indicated:

	Three Months Ended March 31,
($ in thousands)	2022		2021		$ Change		% Change
Operating expenses:
Research and development	$	12,898	$	5,652	$	7,246	128%
Sales and marketing	1,501		512		989		193
General and administrative	7,789		2,120		5,669		267
Total operating expenses	22,188		8,284		13,904		168
Loss from operations	(22,188)		(8,284)		(13,904)		168
Other income (expenses), net:
Interest expense, net	(29)		(57)		28		(49.1)
Gain (loss) on revaluation of warrant liabilities	15,664		(8,426)		24,090		N/M
Loss on revaluation of derivative liabilities	—		(138,141)		138,141		N/M
Gain on revaluation of earnout liabilities	840		—		840		N/M
Other income (expenses), net	4		(10)		14		N/M
Total other income (expenses), net	16,479		(146,634)		163,113		N/M
Net loss	$	(5,709)	$	(154,918)	$	149,209	N/M

__________________

N/M = Not meaningful

Revenue

No revenue was recognized for the three months ended March 31, 2022 or 2021. As of March 31, 2022, we did not have any second-generation products fully deployed and we had not yet met revenue recognition criteria. We began shipping our second-generation Energy Warehouses in the third quarter of 2021 and are continuing to install, commission, and test such units. Revenue recognition will be deferred for each unit until written customer acceptance has been received, after system testing, or until we establish a history of successfully achieving customer acceptance for each customer. In the near term, as our products are new, this is likely to be a longer process than when our products are more mature and we have more history of customer acceptance.

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Research and development

Research and development expenses increased by $7,246 thousand or 128% from $5,652 thousand for the three months ended March 31, 2021 to $12,898 thousand for the three months ended March 31, 2022. The increase resulted primarily from increased personnel-related expenses due to expanded headcount and an increase in purchases of materials, including freight.

Sales and marketing

Sales and marketing expenses increased by $989 thousand or 193% from $512 thousand for the three months ended March 31, 2021 to $1,501 thousand for the three months ended March 31, 2022. The increase is primarily due to increased personnel-related expenses due to expanded headcount and fees paid to outside marketing and sales consultants.

General and administrative

General and administrative expenses increased by $5,669 thousand or 267% from $2,120 thousand for the three months ended March 31, 2021 to $7,789 thousand for the three months ended March 31, 2022. The increase is primarily due to increased personnel-related expenses as a result of expanded headcount, increased insurance fees, and fees paid to outside service providers including legal fees covering a variety of corporate matters, accounting fees and external audit fees.

Other income (expenses), net

Interest expense, net

Interest expense, net decreased by $28 thousand from $57 thousand for the three months ended March 31, 2021 to $29 thousand for the three months ended March 31, 2022. The decrease was primarily driven by principal payments on notes payable resulting in lower outstanding borrowings.

Gain (loss) on revaluation of warrant liabilities

The change in fair value of Public and Private warrant liabilities resulted in a loss of $8,426 thousand for the three months ended March 31, 2021 and a gain of $15,664 thousand for the three months ended March 31, 2022. The changes in fair value of warrant liabilities was driven by changes in the market price of Common Stock over the same periods.

Loss on revaluation of derivative liabilities

The loss on revaluation of the Legacy ESS Series C-2 Convertible Preferred Stock Issuance Right was $138,141 thousand for the three months ended March 31, 2021 as a result of ESS increased equity value over the same period.

Gain on revaluation of earnout liabilities

The gain on revaluation of earnout liabilities was $840 thousand for the three months ended March 31, 2022 as a result of the decrease in value of Common Stock over the same period.

Other income (expense), net

Other expenses were $10 thousand for the three months ended March 31, 2021 compared to other income of $4 thousand for the three months ended March 31, 2022.

Liquidity and Capital Resources

Since our inception, we have financed our operations primarily through the issuance of and sale of equity and debt securities and loan agreements. We have incurred significant losses and have negative cash flows from operations. As of March 31, 2022, we had an accumulated deficit of $546,319 thousand. Management expects to continue to incur additional substantial losses in the foreseeable future as a result of our research and development and other operational activities. As of March 31, 2022, we had unrestricted cash and cash equivalents of $212,331 thousand, which is available to fund future operations. We believe that our unrestricted cash and cash equivalents as of March 31, 2022 will enable us to maintain our operations for a period of at least 12 months following the filing date of our financial statements.

We have a $1,000 thousand note payable with Silicon Valley Bank that is secured by significantly all of our property, except for our intellectual property. The note principal is due in monthly installments of $28 thousand beginning in March 2019 with an original maturity date of July 1, 2021; however, the maturity date was modified and extended to January 1, 2023. In March 2020, we amended the note payable and borrowed an additional $4,000 thousand. The $4,000 thousand note payable’s original maturity date was January 1, 2023; however, the maturity date was modified and extended to September 1, 2022. The note bears interest at 0.50% below the bank’s prime rate (3.00% rate at March 31, 2022).

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The following table summarizes cash flows from operating, investing and financing activities for the periods presented (in thousands):

	Three Months Ended March 31,
	2022		2021
Net cash used in operating activities	$	(19,374)	$	(6,483)
Net cash used in investing activities	(4,041)		(133)
Net cash (used in) provided by financing activities	(3,244)		11,878

Cash flows from operating activities:

Our cash flows used in operating activities to date have been primarily comprised of costs related to research and development of our energy storage products, building awareness of our products’ capabilities and other general and administrative activities. We expect our expenses related to research and development, sales and marketing, and general and administrative activities to increase.

Net cash used in operating activities was $19,374 thousand for the three months ended March 31, 2022, which is comprised of net loss of $5,709 thousand, noncash changes in the fair value of warrant liabilities of $15,664 thousand and earnout liabilities of $840 thousand, partially offset by stock-based compensation of $2,760 thousand. Net changes in operating assets and liabilities used $406 thousand of cash driven by an increase in accounts payable and other accrued liabilities partially offset by cash collections on accounts receivable and a decrease in prepaid expenses and other assets.

Net cash used in operating activities was $6,483 thousand for the three months ended March 31, 2021, which is comprised of net loss of $154,918 thousand, offset by noncash changes in derivative liabilities of $138,141 thousand and changes to warrant liabilities of $8,426 thousand. Net changes in operating assets and liabilities provided $1,588 thousand of cash primarily due to an increase in accrued and other current liabilities.

Cash flows from investing activities:

Our cash flows from investing activities have been comprised primarily of purchases of property and equipment.

Net cash used in investing activities was $4,041 thousand and $133 thousand for the three months ended March 31, 2022 and 2021, respectively, which relates to purchases of property and equipment. Purchases of property and equipment during the three months ended March 31, 2022 primarily relate to our investment in automating production.

Cash flows from financing activities:

Through March 31, 2022, we have raised capital from the Business Combination and financed our operations through the issuance of debt and equity securities and loan agreements.

Net cash used in financing activities was $3,244 thousand for the three months ended March 31, 2022, which is comprised of repurchases of shares from employees for income tax withholding purposes of $2,808 thousand and principal payments on notes payable of $483 thousand.

Net cash provided by financing activities was $11,878 thousand for the three months ended March 31, 2021, which is primarily comprised of $11,461 thousand of proceeds from the issuance of Legacy ESS Series C-2 Preferred Stock, net of issuance costs as well as proceeds from stock option exercises.

Contractual Obligations and Commitments

Our contractual obligations and other commitments as of March 31, 2022 consist of lease commitments and notes payable. We also have a standby letter of credit that serves as security for certain operating leases for office and manufacturing space. The letter of credit is fully secured by restricted certificate of deposit accounts. There was no draw against the letter of credit during the three months ended March 31, 2022. Additionally, we are committed to non-cancellable purchase commitments of $23,344 thousand as of March 31, 2022.

Off-Balance Sheet Arrangements

We are not a party to any off-balance sheet arrangements, including guarantee contracts, retained or contingent interests, or unconsolidated variable interest entities that either have, or are reasonably likely to have, a current or future material effect on our financial statements.

Critical Accounting Policies and Estimates

The preparation of consolidated financial statements in conformity with GAAP requires that management apply accounting policies and make estimates and assumptions that affect amounts reported in the statements. The following accounting

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policies represent those that management believes are particularly important to the consolidated financial statements and that require the use of estimates, assumptions, and judgments to determine matters that are inherently uncertain.

Research and Development

We are in the research and development phase. Our product offering relies heavily on new technology currently undergoing development and does not yet meet standard specifications to be sold commercially. Therefore, all related costs are currently accounted for as part of research and development expense in the consolidated statement of operations. The criteria established to determine when commercialization has been reached includes the length of time the units have been operational in the field and the level of performance at which those units operate. As we transition from the research and development phase and into a full commercial phase, all inventoriable costs will be capitalized. As of March 31, 2022, the criteria for commercialization has not yet been met.

Revenue Recognition

Revenue is earned from the sales of energy storage systems and is derived from customer contracts. Revenue is recognized in an amount that reflects the consideration to which we expect to be entitled in exchange for transferring the promised goods and/or services to the customer, when or as our performance obligations are satisfied which includes estimates for variable consideration, including liquidated damages. For product sales of energy storage systems, our performance obligations are satisfied at the point in time when the customer obtains control of the system (i.e. upon customer acceptance). Payment terms generally include advance payments to reserve capacity and/or upon issuance of the customer’s purchase order, shipment readiness, with the remainder due upon delivery and commissioning of system.

In instances where there are multiple performance obligations in a single contract, we allocate the consideration to the various obligations in the contract based on the relative stand-alone selling price method. When the stand-alone selling price is not observable, revenue is determined based on a best estimate of selling price using cost plus a reasonable margin or by using market data for comparable products.

Revenue recognition is deferred for each unit until written customer acceptance has been received, after system testing, or until we establish a history of successfully achieving customer acceptance for each customer. In the near term, as our products are new, this is likely to be a longer process than when our products are more mature and we have more of a history with customer acceptance.

Emerging Growth Company Status

We are an “emerging growth company” as defined in Section 2(a) of the Securities Act and have elected to take advantage of the benefits of the extended transition period for new or revised financial accounting standards. We expect to remain an emerging growth company at least during the 2022 fiscal year and expect to continue to take advantage of the benefits of the extended transition period, although we may decide to early adopt such new or revised accounting standards to the extent permitted by such standards. This may make it difficult or impossible to compare our financial results with the financial results of another public company that is either not an emerging growth company or is an emerging growth company that has chosen not to take advantage of the extended transition period exemptions because of the potential differences in accounting standards used.

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Market risk represents the risk of loss that may impact our financial position because of adverse changes in financial market prices and rates. Our market risk exposure is primarily a result of exposure resulting from potential changes in interest rates. We do not hold financial instruments for trading purposes. We maintain cash in bank deposits, which at times may exceed federally insured limits. We have not experienced any losses in such accounts.

Interest Rate Risk

Our exposure to changes in interest rates relates primarily to our cash equivalents and restricted cash as well as outstanding notes payable.

As of March 31, 2022, we had cash, cash equivalents and restricted cash of $213,573 thousand. Cash equivalents and restricted cash are primarily comprised of money market funds and certificates of deposit. Our investment strategy is focused on the preservation of capital and supporting our liquidity requirements. We do not enter into investments for trading or speculative purposes.

As of March 31, 2022 and December 31, 2021, we had outstanding variable rate notes payable with an aggregate carrying amount of $3,300 thousand and $3,769 thousand, respectively. The notes bear interest at 0.50% below the bank’s prime rate (3.00% and 2.75% at March 31, 2022 and December 31, 2021, respectively). A hypothetical 100 basis point change in

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interest rates would not have a material impact on the interest expense on our notes payable as of March 31, 2022 and December 31, 2021.

ITEM 4. CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

We have established disclosure controls and procedures that are designed to ensure that the information required to be disclosed by us in the reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in SEC rules and forms and that such information is accumulated and communicated to management, including our principal executive officer and principal financial officer, as appropriate to allow timely decisions regarding required disclosure.

Under the supervision and with the participation of our management, including our principal executive officer and principal financial officer, we conducted an evaluation of the effectiveness of our disclosure controls and procedures as required under Rules 13a-15(e) and 15d-15(e) under the Exchange Act as of the end of the period covered by this report. Based on that evaluation, our principal executive officer and principal financial officer have concluded that the Company’s disclosure controls and procedures were not effective due to an existing material weakness related to the operating effectiveness of internal controls over the review and analysis of certain transactions within our financial statement close process.

Management’s Remediation Initiatives

We have taken and will continue to take steps to remediate the identified unremediated material weakness and enhance our internal controls, including the following:

•We have hired additional personnel and are continuing to expand our team. We are further designing and implementing a formalized internal control framework, including over journal entries and management review controls.

•We are continuing our efforts to improve and strengthen our control processes and procedures to fully remediate these deficiencies. Our management will continue to work with outside advisors to ensure that our controls and procedures are adequate and effective.

Changes in Internal Control over Financial Reporting

In March 2022, the Company implemented a new stock plan administration platform which resulted in a material change in the Company’s internal control over financial reporting. Other than the Company’s new stock plan administration platform and the actions taken as described in Management’s Remediation Initiatives above to improve the Company’s internal control over financial reporting, there have been no changes in our internal control over financial reporting during the fiscal quarter ended March 31, 2022 that materially affected, or which are reasonably likely to materially affect, our internal control over financial reporting.

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Part II – Other Information

ITEM 1. LEGAL PROCEEDINGS

From time to time, we may become involved in legal proceedings arising in the ordinary course of our business. We are not currently a party to any material legal proceedings, nor, to our knowledge, is any material legal proceeding threatened against us. In the future, we may become involved in legal proceedings that arise in the ordinary course of business, the outcome of which, if determined adversely to us, could individually or in the aggregate have a material adverse effect on our business, financial condition and results of operations.

ITEM 1A. RISK FACTORS

Investing in our Common Stock involves a high degree of risk. Before making an investment decision, you should consider carefully the risks and uncertainties described below, together with all of the other information in this Quarterly Report on Form 10-Q, including our consolidated financial statements and related notes thereto included elsewhere in this Quarterly Report on Form 10-Q and in our other filings with the Securities and Exchange Commission, before deciding whether to invest in our Common Stock. Our business, operating results, financial condition or prospects could also be harmed by risks and uncertainties not currently known to us or that we currently do not believe are material. If any of the risks actually occur, our business, operating results, financial condition and prospects could be adversely affected. In that event, the market price of our Common Stock could decline, and you could lose part or all of your investment. References to “we,” “our,” or “us” generally refer to ESS, unless otherwise specified.

Summary Risk Factors

Our business is subject to numerous risks and uncertainties. The following is a summary of the principal risks we face:

•We face significant barriers in our attempts to produce our energy storage products, our energy storage products are still under development, and we may not be able to successfully develop our energy storage products at commercial scale. If we cannot successfully overcome those barriers, our business will be negatively impacted and could fail;

•We are in the early stage of commercialization. In addition, certain aspects of our technology have not been fully field tested. If we are unable to develop our business and effectively commercialize our energy storage products as anticipated, we may not be able to generate revenues or achieve profitability;

•We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products. We have experienced significant disruptions to key supply chains, shipping times, manufacturing times, and associated costs;

•Continued delays in our supply chain or the inability to procure needed raw materials and components could further harm our ability to manufacture and commercialize our energy storage products;

•We have experienced and may experience delays in the future, disruptions, or quality control problems in our manufacturing operations;

•Our ability to expand depends on our ability to hire, train and retain an adequate number of manufacturing employees, in particular employees with the appropriate level of knowledge, background and skills;

•We have experienced disruption related to COVID-19, which continues to cause uncertainty;

•We may be unable to adequately control the costs associated with our operations and the components necessary to build our energy storage products, and if we are unable to reduce our cost structure and effectively scale our operations in the future, our ability to become profitable may be impaired;

•We rely on complex machinery for our operations, and the production of our iron flow batteries involves a significant degree of risk and uncertainty in terms of operational performance and costs;

•Our expectations for future operating and financial results and market growth rely in large part upon assumptions and analyses developed by us. If these assumptions or analyses prove to be incorrect, our actual operating results may be materially different from our anticipated results;

•We have a history of losses and have to deliver significant business growth to achieve sustained, long-term profitability and long-term commercial success;

•Our warranty insurance provided by Munich Re is important to many potential customers. Should we be unable to maintain our relationship with Munich Re and be unable to find a similar replacement, demand for our products may suffer;

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•Failure to deliver the benefits offered by our technology, or the emergence of improvements to competing technologies, could reduce demand for our energy storage products and harm our business;

•Our plans are dependent on the development of a market acceptance of our products;

•We may face regulatory challenges to or limitations on our ability to sell our Energy Centers and Energy Warehouses directly in certain markets. Expanding operations internationally could expose us to additional risks;

•If we fail to protect, or incur significant costs in defending, our intellectual property and other proprietary rights, then our business and results of operations could be materially harmed; and

•As we endeavor to expand our business, we will incur significant costs and expenses, which could outpace our cash reserves. Unfavorable conditions or disruptions in the capital and credit markets may adversely impact business conditions and the availability of credit.

The following risk factors apply to our business and operations. These risk factors are not exhaustive, and investors are encouraged to perform their own investigation with respect to our business, financial condition and prospects. We may face additional risks and uncertainties that are not presently known to us, or that we currently deem immaterial, which may also impair our business. The following discussion should be read in conjunction with the financial statements and notes to the financial statements included elsewhere in this Quarterly Report on Form 10-Q.

Risks Related to Our Technology, Products and Manufacturing

We face significant barriers in our attempts to produce our energy storage products, our energy storage products are still under development, and we may not be able to successfully develop our energy storage products at commercial scale. If we cannot successfully overcome those barriers, our business will be negatively impacted and could fail.

Producing long-duration iron flow batteries that meet the requirements for wide adoption by commercial and utility-scale energy storage applications is a difficult undertaking. We are still in the early stage of commercialization and face significant challenges in completing the development of our containerized energy storage products and in producing our energy storage products in commercial volumes. Some of the development challenges that could prevent the introduction of our iron flow batteries include difficulties with (i) increasing the volume, yield, reliability and uniformity of the porous polyethylene separators and cells housed within the power module of our batteries, (ii) increasing the size and layer count of the multi-layer cells within the power module of our batteries, (iii) increasing manufacturing capacity to produce the volume of cells needed for our energy storage products, (iv) installing and optimizing higher volume manufacturing equipment, (v) packaging our batteries to ensure adequate cycle life, (vi) cost reduction, (vii) qualifying new vendors, (viii) expanding supply chain capacity, (ix) the completion of rigorous and challenging battery safety testing required by our customers or partners, including but not limited to, performance, life and abuse testing and (x) the development of the final manufacturing processes.

Our Energy Warehouses are in the development stage. As of March 31, 2022, we did not have any second-generation S200 iron flow batteries fully deployed and there may be significant yield, cost, performance and manufacturing process challenges to be solved prior to commercial production and use. We are likely to encounter further engineering challenges as we increase the capacity and efficiency of our batteries. If we are not able to overcome these barriers in developing and producing our iron flow batteries, our business could fail.

Our second-generation energy storage products and S200 batteries are manufactured on our first-generation (“Gen I”) automation line. The Gen I automation line requires qualified labor to inspect the parts to ensure proper assembly. We have already experienced various issues related to the scaling up of the manufacturing process, and the lack of qualified labor to inspect our assemblies may further slow our production and impact our production costs and schedule. We have commissioned third parties to develop more sophisticated automation lines to minimize the required skilled labor, however, delays in production and delivery of the new second-generation manufacturing line are not in our control. If we experience delivery or installation delays under our customer contracts, we could experience order cancellations and lose business as well as face lawsuits seeking liquidated damages.

Even if we complete development and achieve volume production of our iron flow batteries, if the cost, performance characteristics or other specifications of the batteries fall short of our targets, our sales, product pricing and margins would likely be adversely affected.

We are in the early stage of commercialization. In addition, certain aspects of our technology have not been fully field tested. If we are unable to develop our business and effectively commercialize our energy storage products as anticipated, we may not be able to generate revenues or achieve profitability.

The growth and development of our operations will depend on the successful commercialization and market acceptance of our energy storage products and our ability to manufacture products at scale while timely meeting customers’ demands.

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There is no certainty that, once shipped, our products will operate as expected, and we may not be able to generate sufficient customer confidence in our latest designs and ongoing product improvements. There are inherent uncertainties in our ability to predict future demand for our energy storage products and, as a consequence, we may have inadequate production capacity to meet demand, or alternatively, have excess available capacity. Our inability to predict the extent of customer adoption of our proprietary technologies in the already-established traditional energy storage market makes it difficult to evaluate our future prospects.

As of March 31, 2022, we did not have any second-generation products fully deployed and we had not yet met revenue recognition criteria. We began shipping our second-generation Energy Warehouses in the third quarter of 2021 and we are continuing to install, commission, and test such units. Any significant problems in the production process could result in unplanned increases to production costs and production delays. In addition, although we believe our iron flow battery technology is field tested and ready for sale, there are no assurances that our proprietary technologies, such as our Proton Pump, will operate as expected and with consistency. We have also experienced grid compatibility issues, which has required and will continue to require an adjustment of our power electronics on a site-by-site basis. Our Energy Center product is still being developed and has not been completely designed or produced. In addition, certain operational characteristics of our Energy Warehouse or Energy Center products with S200 batteries, such as cyclability with no degradation, have never been witnessed in the field. If our batteries are damaged during shipment, we may be required to replace such units. Once our Energy Warehouse or Energy Center products with S200 batteries are installed and used, we may discover further aspects of our technology that require improvement. Any of these developments could delay existing contracts and new sales, result in order cancellations and negatively impact the market’s acceptance of our technology. If we experience significant delays or order cancellations, or if we fail to develop and install our energy storage products in accordance with contract specifications, then our operating results and financial condition could be adversely affected. In addition, there is no assurance that if we alter or change our energy storage products in the future, that the demand for these new products will develop, which could adversely affect our business and any possible revenues. If our energy storage products are not deemed desirable and suitable for purchase and we are unable to establish a customer base, we may not be able to generate revenues or attain profitability.

We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products. We also depend on vendors for the shipping of our energy storage products. Continued delays in our supply chain and shipments could further harm our ability to manufacture and commercialize our energy storage products.

We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products, including power module components (e.g., bipolar plates, frames, end plates and separators), shipping containers, chemicals and electronic components. We will need to maintain and significantly grow our access to key raw materials and control our related costs. We use various raw materials and components to construct our energy storage products, including polypropylene, iron and potassium chloride, that are critical to our manufacturing process. We also rely on third-party suppliers for injected molded parts and power electronics which undergo a qualification process that takes four to 12 months.

The cost of components for our iron flow batteries, whether manufactured by our suppliers or by us, depends in part upon the prices and availability of raw materials. In recent periods, we have seen an increase in costs for a wide range of materials and components. Additionally, supply chain disruptions and access to materials have impacted and continue to impact our vendors and suppliers’ ability to deliver materials and components to us in a timely manner. We have experienced significant disruptions to key supply chains, shipping times, shipping availability, manufacturing times, and associated costs, both with respect to the sourcing of supplies and the delivery of our products. We experienced and continue to experience delays to deliveries, vendor quality issues, as well as increases in our supply costs of many of our key components, including polypropylene, resin, power electronics, circuit board components and shipping containers. We expect such delays to continue at least for the remainder of 2022 and the adverse impact of the recent COVID-19 surge in China and resultant lock down on supply chains may further exacerbate the issue. It is also possible that the semiautomated and automated production lines that we have contracted for the second quarter of 2022 and the fourth quarter of 2022, respectively, may also face delays in delivery and/or installation due to similar supply chain issues. If these issues persist, they may further delay our ability to produce our products and to recognize revenue, particularly for our larger scale Energy Center products (see also “Part I. Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Components of Results of Operations—Revenue”).

We expect prices for these materials to continue to fluctuate and their available supply may be unstable, depending on market conditions and global demand for these materials, including as a result of increased global production of batteries and energy storage products. For example, our Proton Pump is manufactured with certain raw materials, which not only include precious and non-precious metals but also carbon, graphite and thermoplastics, the prices of which have historically fluctuated on a cyclical basis and depend on a variety of factors over which we have no control. We have also experienced

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increased prices and/or inconsistent quality and supply of other electrical components and power module components including frames, end plates and separators. Any reduced availability of these materials may impact our access to cells and any further increases in their prices may reduce our profitability if we cannot recoup the increased costs through increased prices for our products. In addition, we utilize shipping containers to house our iron flow batteries within our Energy Warehouses and Energy Centers. Shipping delays caused by various economic, weather and COVID-19 pandemic effects have created a shortage in shipping containers and other supply chain delays. We have limited visibility into these supply chain disruptions and increased shipping container costs. Given that our energy storage products rely on the availability of shipping containers, such shortages may reduce our profitability if we are not able to pass the increased costs to our customers. Moreover, any such attempts to increase product prices may harm our brand, prospects and operating results.

In addition, the conflict between Russia and Ukraine could lead to disruption, instability and volatility in global markets and industries that could negatively impact our operations and our supply chain. The U.S. government and other governments have already imposed severe sanctions and export controls against Russia and Russian interests and may yet impose additional sanctions and controls. The impact of these measures, as well as potential responses to them by Russia, is currently unknown and they could adversely affect our business, supply chain, partners or customers.

We depend on third-party vendors for the shipping of our energy storage products. Recent conditions have also created disruptions in the logistics sector making it more challenging to find trucks to ship our products. Given current conditions, the shipping of our product to customers internationally in a timely and cost-effective manner may also prove challenging. The failure to deliver our products in a timely fashion or within budget may also harm our brand, prospects and operating results.

We do not know whether we will be able to maintain long-term supply relationships with our critical suppliers, or secure new long-term supply relationships on terms that will allow us to achieve our objectives, if at all.

We continually evaluate new suppliers, and we are currently qualifying several new suppliers. However, there are a limited number of suppliers for some of the key components of our products and we have, to date, fully qualified only a very limited number of such suppliers. Therefore, we have limited flexibility in changing suppliers. For example, we currently only have one supplier of bipolar plates, which is a critical component of our iron flow batteries. In addition, we have had issues with inconsistent quality and supply of other key power module components. We do not know whether we will be able to maintain long-term supply relationships with our critical suppliers, or secure new long-term supply relationships on terms that will allow us to achieve our objectives, if at all. A supplier’s failure to develop and supply components in a timely manner or to supply components that meet our quality, quantity or cost requirements or our technical specifications, or our inability to obtain alternative sources of these components on a timely basis or on terms acceptable to us, could each harm our ability to manufacture and commercialize our energy storage products. In addition, to the extent the processes that our suppliers use to manufacture components are proprietary, we may be unable to obtain comparable components from alternative suppliers, all of which could harm our business, financial condition and results of operations.

In the long term, we intend to supplement certain components from our suppliers by manufacturing them ourselves, which we believe will be more efficient, manufacturable at greater volumes and cost-effective than currently available electronic components. However, our efforts to develop and manufacture such electronic components have required and may require significant investments, and there can be no assurance that we will be able to accomplish this in the timeframes that we have planned or at all. If we are unable to do so, we may have to curtail our iron flow battery and energy storage product production or procure additional raw materials and electronic components from suppliers at potentially greater costs, either of which may harm our business and operating results.

We may experience delays, disruptions, or quality control problems in our manufacturing operations.

Our manufacturing and testing processes will require significant technological and production process expertise and modification to support our projected business objectives. We have already experienced various issues related to the scaling up of the manufacturing process and while we seek to prevent the reoccurrence of such issues through the training of our manufacturing personnel to properly operate the manufacturing process, there can be no assurance that such issues will not reoccur in the future. In addition, any change in our processes could cause one or more production errors, requiring a temporary suspension or delay in our production line until the errors can be researched, identified, and properly addressed and rectified. This may occur particularly as we introduce new products, modify our engineering and production techniques, and/or expand our capacity. In addition, our failure to maintain appropriate quality assurance processes could result in increased product failures, loss of customers, increased warranty reserves, increased production, and logistical costs and delays. Any of these developments could lead to current and potential customers cancelling or postponing their purchases of our products, which could have a material adverse effect on our business, financial condition and results of operations.

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The COVID-19 pandemic has caused significant uncertainty in the United States and global economies as well as the markets we serve and could adversely affect our business, financial condition and results of operations.

While new cases of COVID-19 have recently been trending downward, there are no assurances that the pandemic has run its course. New cases, fueled by new variants and mutant strains, may continue to surge in certain parts of the world, which may result in authorities reimplementing measures to contain the virus, including travel bans and restrictions, quarantines, shelter-in-place orders, and business limitations and shutdowns. The recent surge in China and resultant lock down has begun to adversely affect supply chains, which potentially may have an impact on the global economy but possibly on our business as well. We remain unable to accurately predict the full impact that COVID-19 will have on our results of operations, financial condition, liquidity and cash flows due to numerous uncertainties, including the duration and severity of the pandemic and containment measures. Our compliance with containment and mitigation measures materially impacted our day-to-day operations, and there can be no guaranty that a resurgence in the pandemic will not disrupt our business and operations or impair our ability to implement our business plan successfully.

In addition, as government support measures designed to mitigate the impact of the COVID-19 pandemic are phased out, we may experience an extended global economic downturn which could affect demand for our products and services and impact our results and financial condition. For example, we may be unable to collect receivables from certain customers. Also, a decrease in orders in a given period could negatively affect our revenues in future periods, particularly if experienced on a sustained basis. A resurgence of the pandemic may also have the effect of heightening many of the other risks described in these “Risk Factors”, particularly those risks associated with our customers and supply chain.

We may be unable to adequately control the costs associated with our operations and the components necessary to build our energy storage products, and if we are unable to reduce our cost structure and effectively scale our operations in the future, our ability to become profitable may be impaired.

Our ability to become profitable in the future will not only depend on our ability to successfully market our iron flow batteries, Energy Centers and Energy Warehouses, but also to control costs to manufacture our iron flow batteries, Energy Centers, and Energy Warehouses. If we are unsuccessful in our cost-reduction plans or if we experience design or manufacturing defects or other failures of our S200 battery as result of these design changes, we could incur significant manufacturing and re-engineering costs. In addition, we will require significant capital to further develop and grow our business and expect to incur significant expenses, including those relating to research and development, raw material procurement, leases, sales and distribution as we build our brand and market our products, and general and administrative costs as we scale our operations. If we are unable to cost-efficiently design, manufacture, market, sell and distribute our energy storage products, our margins, profitability and prospects would be materially and adversely affected.

In addition, our Proton Pump is manufactured with certain raw materials, such as platinum, the prices of which have historically fluctuated on a cyclical basis and depend on a variety of factors over which we have no control. Substantial increases in the prices of raw materials would increase our operating costs and could adversely affect our profitability. The price of oil likewise fluctuates on a cyclical basis and may be subject to sustained cost pressure given geopolitical uncertainty, which in turn could affect the cost of making, distributing and transporting our products. If we are unable to pass any such increased costs to our customers, this could have a material adverse effect on our business, financial condition and results of operations.

In order to achieve our business plan, we must continue to reduce the manufacturing and development costs for our iron flow batteries, Energy Centers and Energy Warehouses to expand our market. Additionally, certain of our existing customer contracts were entered into based on projections regarding costs reductions that assume continued advances in our manufacturing and services processes that we may be unable to realize. The cost of components and raw materials, for example, could increase in the future, offsetting any successes in reducing our manufacturing costs. Any such increases could slow our growth and cause our financial results and operational metrics to suffer. In addition, we may face increases in our other expenses including increases in wages or other labor costs as well as installation, marketing, sales or related costs. In order to expand into new markets (especially markets in which the price of electricity from the grid is lower) we will need to continue to reduce our costs. Increases in any of these costs or our failure to achieve projected cost reductions could adversely affect our results of operations and financial condition and harm our business and prospects. If we are unable to reduce our cost structure in the future, we may not be able to achieve profitability, which could have a material adverse effect on our business and our prospects.

Further, we have not yet produced any iron flow batteries, Energy Warehouses or Energy Centers at volume and our expected cost advantage for the production of these products at scale, compared to conventional lithium-ion cells, will require us to achieve rates of throughput, use of electricity and consumables, yield, and rate of automation demonstrated for mature battery, battery material, and manufacturing processes, that we have not yet achieved. If we are unable to achieve these targeted rates, our business will be adversely impacted.

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We rely on complex machinery for our operations and the production of our iron flow batteries involves a significant degree of risk and uncertainty in terms of operational performance and costs.

We rely heavily on complex machinery for our operations and the production of our iron flow batteries, and this equipment has not yet been qualified to operate at large-scale manufacturing. The work required to integrate this equipment into the production of our iron flow batteries is time intensive and requires us to work closely with the equipment provider to ensure that it works properly for our unique iron flow battery technology. This integration work will involve a significant degree of uncertainty and risk and may result in a delay in the scaling up of production or result in additional cost to our iron flow batteries.

Our manufacturing facilities will require large-scale machinery, particularly for the automated production line. Such machinery is likely to suffer unexpected malfunctions from time to time and will require repairs and spare parts to resume operations, which may not be available when needed. Unexpected malfunctions of our production equipment may significantly affect the intended operational efficiency or yield. Some examples would be inadequate bonding of the battery cells resulting in overboard or internal leakage, damage to the separator, or cracked bipolar or monopolar plates. In addition, because this equipment has never been used to build iron flow batteries, the operational performance and costs associated with this equipment can be difficult to predict and may be influenced by factors outside of our control, such as, but not limited to, failures by suppliers to deliver necessary components of our energy storage products in a timely manner and at prices and volumes acceptable to us, environmental hazards and remediation, difficulty or delays in obtaining governmental permits, damages or defects in systems, industrial accidents, fires, seismic activity and other natural disasters.

Operational problems with our manufacturing equipment could result in the personal injury to or death of workers, the loss of production equipment, damage to manufacturing facilities, monetary losses, delays and unanticipated fluctuations in production. In addition, operational problems may result in environmental damage, administrative fines, increased insurance costs and potential legal liabilities. All of these operational problems could have a material adverse effect on our business, cash flows, financial condition or results of operations.

Our future success depends in part on our ability to increase our production capacity, and we may not be able to do so in a cost-effective manner. If we elect to expand our production capacity by constructing one or more new manufacturing facilities, we may encounter challenges relating to the construction, management and operation of such facilities.

In order to grow our business, we will need to increase our production capacity. For example, our current manufacturing capacity may not be sufficient to meet our planned 2022 production targets and we are currently seeking to expand our capacity. Our ability to plan, construct and equip additional manufacturing facilities is subject to significant risks and uncertainties, including but not limited to the following:

•The expansion or construction of any manufacturing facilities will be subject to the risks inherent in the development and construction of new facilities, including risks of delays and cost overruns as a result of factors outside our control, which may include delays in government approvals, burdensome permitting conditions, and delays in the delivery or installation of manufacturing equipment and subsystems that we manufacture or obtain from suppliers, similar to or more severe than what we have experienced recently.

•In order for us to expand internationally, we anticipate entering into strategic partnerships, joint venture and licensing agreements that allow us to add manufacturing capability outside of the United States. Adding manufacturing capacity in any international location will subject us to new laws and regulations including those pertaining to labor and employment, environmental and export / import. In addition, any such expansion brings with it the risk of managing larger scale foreign operations.

•We may be unable to achieve the production throughput necessary to achieve our target annualized production run rate at our current and future manufacturing facilities.

•Manufacturing equipment may take longer and cost more to engineer and build than expected, and may not operate as required to meet our production plans.

•We may depend on third-party relationships in the development and operation of additional production capacity, which may subject us to the risk that such third parties do not fulfill their obligations to us under our arrangements with them.

•We may be unable to attract or retain qualified personnel.

If we are unable to expand our manufacturing facilities, we may be unable to further scale our business, which would negatively affect our results of operations and financial condition. We cannot provide any assurances that we would be able

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to successfully establish or operate our manufacturing facility in a timely or profitable manner, or at all, or within any expected budget for such a project. The construction of any such facility would require significant capital expenditures and result in significantly increased fixed costs. If we are unable to transition manufacturing operations to any such new facilities in a cost-efficient and timely manner, then we may experience disruptions in operations, which could negatively impact our business and financial results. Further, if the demand for our products decreases or if we do not produce the expected output after any such new facility is operational, we may not be able to spread a significant amount of our fixed costs over the production volume, thereby increasing our per product fixed cost, which would have a negative impact on our business, financial condition and results of operations.

In addition, if any of our partners suffer from capacity constraints, deployment delays, work stoppages or any other reduction in output, we may be unable to meet our delivery schedule, which could result in lost revenue and deployment delays that could harm our business and customer relationships. If the demand for our iron flow batteries, Energy Centers and Energy Warehouses or our production output decreases or does not rise as expected, we may not be able to spread a significant amount of our fixed costs over the production volume, resulting in a greater than expected per unit fixed cost, which would have a negative impact on our financial condition and our results of operations.

Our ability to expand our manufacturing capacity would also greatly depend on our ability to hire, train and retain an adequate number of manufacturing employees, in particular employees with the appropriate level of knowledge, background and skills. Should we be unable to hire or train such employees, our business and financial results could be negatively impacted.

We have in the past and may be compelled in the future to undertake product recalls or take other actions, which could adversely affect our business, prospects, operating results, reputation and financial condition.

We have in the past and may be compelled in the future to undertake product recalls. For example, in the past we had to recall our Gen I battery modules due to vendors not properly manufacturing the parts to our specifications. We have also had to replace and are still in the process of replacing certain components of our Gen II battery modules delivered to customers to date. Any quality issues can result in single module failures or can result in a cascade of numerous failures. Failures in the field can result in a single module replacement or may result in a total recall depending on the severity or contamination to the remainder of the system.

Any product recall in the future may result in adverse publicity, damage our reputation and adversely affect our business, financial condition and results of operations. In the future, we may, voluntarily or involuntarily, initiate a recall if any of our Energy Warehouses, Energy Centers, iron flow batteries, Proton Pump or components prove to be defective or noncompliant with applicable safety standards. Such recalls, whether caused by systems or components engineered or manufactured by us or our suppliers, would involve significant expense and diversion of management’s attention and other resources, which could adversely affect our brand image in our target market and our business, financial condition and results of operations.

Our relationship with SBE, an affiliate of SoftBank Group Corp., is subject to various risks which could adversely affect our business and future prospects. There are no assurances that we will be able to commercialize iron flow batteries from our joint development relationship with SBE. In addition, SBE has no obligation to order any energy storage products from us under the framework agreement, including at any price point.

In April 2021, we signed a framework agreement, dated as of March 31, 2021, with SBE to supply our energy storage products to SBE in support of its market activities. Under this agreement, we have made various commitments to meet SBE’s potential need for our energy storage products and are obligated to reserve a certain percentage of our manufacturing capacity to meet SBE’s future needs, subject to periodic reviews of its firm and anticipated orders, which may negate those capacity reservations if no firm demand is realized. However, SBE is under no obligation to place any firm orders with us at any price point, and any future orders may be subject to future pricing or other commercial or technical negotiations, which we may not be able to satisfy, resulting in a diminished potential value of this relationship to us. To date, no orders have been placed under the framework agreement.

SBE, and any other business partners in the future, may have economic, business or legal interests or goals that are inconsistent with our goals. Any disagreements with SBE or other future business partners may impede our ability to maximize the benefits of these partnerships and slow the commercialization of our iron-flow batteries. Future commercial or strategic counterparties may require us, among other things, to pay certain costs or to make certain capital investments or to seek their consent to take certain actions. In addition, if SBE is unable or unwilling to meet its economic or other obligations under our partnership arrangements, we may be required to fulfill those obligations alone. These factors could result in a material adverse effect on our business and financial results.

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The execution of our strategy to expand into new markets through strategic partnerships, joint ventures and licensing arrangements is in a very early stage and is also subject to various risks which could adversely affect our business and future prospects.

We may enter into strategic partnerships, joint ventures and licensing arrangements to expand our business and enter into new markets. However, we currently have no such arrangements in place and there is no assurance that we will be able to consummate any such arrangements as contemplated to commercialize our energy storage products. For example, we may enter into the Australian market through a joint venture to be formed with the purpose of manufacturing, distributing and operating our energy storage products in the region. We are currently in discussions with a potential joint venture partner that will include building manufacturing facilities. However, there can be no assurance that we will be able to enter into a binding agreement or agree to pricing or other terms that are financially beneficial or otherwise not unfavorable for us. If we are unsuccessful in securing a joint venture arrangement, we will need to find an alternative plan to enter the Australian market. Even if we are able to successfully secure a joint venture arrangement in Australia, there can be no assurance that we will be able to complete the development of manufacturing facilities and successfully manufacture, distribute and operate our energy storage products in that region.

Any future strategic partnerships, joint ventures or licensing arrangements may require us, among other things, to pay certain costs, make certain capital investments or to seek the partner’s consent to take certain actions. In addition, if a partner is unable or unwilling to meet its economic or other obligations under the respective arrangements, we may be required to either fulfill those obligations alone to ensure the ongoing success of, or to dissolve and liquidate, the partnership, joint venture or licensing arrangement. These factors could result in a material adverse effect on our business, prospects and financial results.

Risks Related to Our Business and Industry

Our expectations for future operating and financial results and market growth rely in large part upon assumptions and analyses developed by us. If these assumptions or analyses prove to be incorrect, our actual operating results may be materially different from our anticipated results.

We operate in rapidly changing and competitive markets and our expectations for future performance are subject to the risks and assumptions made by management with respect to our industry. Operating results are difficult to predict because they generally depend on our assessment of the timing of adoption of our technology and energy storage products, which is uncertain. Expectations for future performance are also subject to significant economic, competitive, industry and other uncertainties and contingencies, all of which are difficult or impossible to predict and many of which are beyond our control, and subsequent developments may affect such expectations. As discussed further elsewhere in this Quarterly Report on Form 10-Q, any future sales and related future cash flows may not be realized in full or at all. Furthermore, our planned expansion into new revenue streams such as franchising opportunities for our energy storage products may never be realized or achieve commercial success, whether because of lack of market adoption of our energy storage products, competition or otherwise. Important factors that may affect the actual results and cause our operating and financial results and market growth expectations to not be achieved include risks and uncertainties relating to our business, industry performance, the regulatory environment, general business and economic conditions and other factors described under the section entitled “Cautionary Note Regarding Forward-Looking Statements” in this Quarterly Report on Form 10-Q.

In addition, expectations for future performance also reflect assumptions that are subject to change and do not reflect revised prospects for our business, changes in general business or economic conditions or any other transaction or event that has occurred or that may occur and that was not previously anticipated. In addition, long-term expectations by their nature become less predictive with each successive year. There can be no assurance that our future financial condition or results of operations will be consistent with our expectations or with the expectations of investors or securities research analysts, which may cause the market price of our Common Stock to decline. If actual results differ materially from our expectations, we may be required to make adjustments in our business operations that may have a material adverse effect on our financial condition and results of operations.

We have a history of losses and have to deliver significant business growth to achieve sustained, long-term profitability and long-term commercial success.

We had net losses on a GAAP basis in each fiscal year since our inception. For the year ended December 31, 2021 and the three-month period ended March 31, 2022, we had $477.1 million and $5.7 million in net losses, respectively. In order to achieve profitability as well as long-term commercial success, we must continue to execute our plan to expand our business, which will require us to deliver on our existing global sales pipeline in a timely manner, increase our production capacity, reduce our manufacturing costs, competitively price and grow demand for our products, and seize new market opportunities by leveraging our proprietary technology and our manufacturing processes for novel solutions and new products. Failure to do one or more of these things could prevent us from achieving sustained, long-term profitability.

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As we transition from our research and development phase and into a full commercial phase, we expect, based on our sales pipeline, to grow revenues. However, our revenue may not grow as expected for a number of reasons, many of which are outside of our control, including a decline in global demand for iron flow battery storage products, increased competition, or our failure to continue to capitalize on growth opportunities. If we are not able to generate and grow revenue and raise the capital necessary to support our operations, we may be unable to continue as a going concern.

Our energy storage products are still under development, and there is no assurance nonbinding pre-orders will be converted into binding orders or sales.

Our business model is focused on building relationships with large customers. To date, we have engaged in limited marketing activities and we have only a limited number of contracts with customers. Our energy storage products are still subject to ongoing development and until the time that the design and development of our energy storage products is complete and is commercially available for purchase, and until we are able to scale up our marketing function to support sales, there will be uncertainty as to customer demand for our energy storage products. In particular, demand for our energy storage products by independent energy developers will depend upon a bankability determination by institutional sources of project finance capital and that determination may be difficult to obtain. The potentially long wait from the time an order is made until the time our energy storage products are delivered, and any delays beyond expected wait times, could also impact user decisions on whether to ultimately make a purchase. There is no assurance that nonbinding pre-orders will be converted into binding orders or sales. Even if we are able to obtain binding orders, customers may limit their volume of purchases initially as they assess our products and whether to make a broader transition to our energy storage products. This may be a long process and will depend on the safety, reliability, efficiency and quality of our energy storage products, as well as the support and service that we offer. It will also depend on factors outside of our control, such as general market conditions, that could impact customer buying decisions. As a result, there is significant uncertainty regarding demand for our energy storage products and the pace and levels of growth that we will be able to achieve.

In addition, with some of our units delivered to customers to date, we have not met the specifications set forth in the purchase contracts for such units. If we do not meet contractual performance specifications of our units, customers may bring claims against us or choose to cancel or postpone orders, which would adversely affect our business, financial condition and results of operations.

Our warranty insurance provided by Munich Re is important to many potential customers. Should we be unable to maintain our relationship with Munich Re and be unable to find a similar replacement, demand for our products may suffer.

Our business is substantially dependent on our relationship with Munich Re. Our warranty insurance provided by Munich Re is important to many potential customers, and such warranty insurance is a bespoke product not widely offered by multiple insurers. There is no assurance that we will be able to maintain our relationship with Munich Re. If Munich Re terminates or significantly alters its relationship with us in a manner that is adverse to our company, our business would be materially adversely affected. Similarly, if we are unable to maintain our relationship with Munich Re, or if our arrangement with Munich Re is modified so that the economic terms become less favorable to us, we may be unable to find a similar replacement warranty insurance and our business would be materially adversely affected.

Failure to deliver the benefits offered by our technology, or the emergence of improvements to competing technologies, could reduce demand for our energy storage products and harm our business.

We believe that, compared to lithium-ion batteries, our energy storage solutions offer significant benefits, including using widely-available, low-cost materials with no rare mineral components, being substantially recyclable at end-of-life, having an approximately twenty-five year product life requiring minimal maintenance, and having a wide thermal operating range that eliminates the need for fire suppression and heating, ventilation and air conditioning equipment, which would otherwise be required for use with lithium-ion batteries.

However, if our manufacturing costs increase, or if our or our customers’ expectations regarding the operation, performance, maintenance and disposal of our energy storage products are not realized, then we could have difficulty marketing our energy storage products as a superior alternative to already-established technologies. This would also impact the market reputation and adoptability of our energy storage products.

We also currently market our energy storage products as having superior cyclability to other energy storage solutions on the market. However, in general, flow batteries have suffered challenges running multiple cycles over their lifetime without experiencing degradation in storage capacity and, in particular, our iron flow batteries have failed at cycling reliably in the past and may fail or have issues cycling in the future if our technology does not operate as expected. If our technology is inadequate or our energy storage solutions fail to operate as expected or designed, current and potential customers may choose to cancel or postpone orders, which would adversely affect our business, financial condition and results of operations.

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In addition, developments of existing and new technologies could improve the cost and usability profile of such alternative technologies, reducing any relative benefits currently offered by our energy storage products, which would negatively impact the likelihood of our energy storage products gaining market acceptance.

Our plans are dependent on the development of market acceptance of our products.

Our plans are dependent upon market acceptance of our products. Iron flow batteries represent an emerging market, and we cannot be sure that potential customers will accept iron flow batteries as a replacement for traditional power sources. In particular, traditional lithium-ion batteries, which are already produced on a large global scale and have widespread market acceptance, offer higher power density and round-trip efficiency than our iron flow batteries. If customers were to place greater value on power density and round-trip efficiency over what we believe to be the numerous other advantages of our technology, then we could have difficulty positioning our iron flow batteries as a viable alternative to traditional lithium-ion batteries and our business would suffer.

As is typical in a rapidly evolving industry, demand and market acceptance for recently introduced products and services are subject to a high level of uncertainty and risk. It is difficult to predict with certainty the size of the energy storage market and its growth rate. The development of a market for our products may be affected by many factors that are out of our control, including:

•the cost competitiveness of our products including availability and output expectations and total cost of ownership;

•the future costs associated with renewable energies;

•perceived complexity and novelty of our technology and customer reluctance to try a new product;

•the market for energy storage solutions and government policies that affect those markets;

•government incentives, mandates or other programs favoring zero carbon energy sources;

•local permitting and environmental requirements;

•customer preference for lithium-ion based technologies, including but not limited to the power density offered by lithium-ion batteries; and

•the emergence of newer, more competitive technologies and products.

If a sufficient market fails to develop or develops more slowly than we anticipate, we may be unable to recover the losses we will have incurred in the development of our products, and we may never achieve profitability.

Our future growth and success depend on our ability to sell effectively to large customers.

Many of our potential customers are electric utilities, and C&I businesses that tend to be large enterprises. Therefore, our future success will depend on our ability to effectively sell our products to such large customers. Sales to these end-customers involve risks that may not be present (or that are present to a lesser extent) with sales to smaller customers. These risks include, but are not limited to, (i) increased purchasing power and leverage held by large customers in negotiating contractual arrangements with us and (ii) longer sales cycles and the associated risk that substantial time and resources may be spent on a potential end customer that elects not to purchase our solutions.

Large organizations often undertake a significant evaluation process that results in a lengthy sales cycle. In addition, product purchases by large organizations are frequently subject to budget constraints, multiple approvals and unanticipated administrative, processing and other delays. Finally, large organizations typically have longer implementation cycles, require greater product functionality and scalability, require a broader range of services, demand that vendors take on a larger share of risks, require acceptance provisions that can lead to a delay in revenue recognition and expect greater payment flexibility, while also having the resources to initiate litigation in the event that a shipment or installation of a product is delayed or if the product does not otherwise meet the customer’s expectations. All of these factors can add further risk to business conducted with these potential customers.

Our project awards and sales pipeline may not convert to contracts, which may have a material adverse effect on our revenue and cash flows.

We expect a significant portion of the business that we will seek in the foreseeable future will be awarded through competitive bidding against other energy storage technologies and other forms of power generation. The competitive bidding process involves substantial costs and a number of risks, including the significant cost and managerial time to prepare bids and proposals for contracts that may not be awarded to us and our failure to accurately estimate the resources and costs that will be required to fulfill any contract we win. In addition, following a contract award, we may encounter significant expense, delay or contract modifications or award revocation as a result of our competitors protesting or

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challenging contracts awarded to us in competitive bidding. Our failure to compete effectively in this procurement environment could adversely affect our revenue and/or profitability.

Some of the project awards we receive and orders we accept from customers require certain conditions or contingencies (such as permitting, interconnection, financing or regulatory approval) to be satisfied, some of which are outside of our control. Certain awards are cancellable or revocable at any time prior to contract execution. The time periods from receipt of an award to execution of a contract, or receipt of a contract to installation may vary widely and are determined by a number of factors, including the terms of the award, governmental policies or regulations that go into effect after the award, the terms of the customer contract and the customer’s site requirements. These same or similar conditions and contingencies may be required by financiers in order to draw on financing to complete a project. If these conditions or contingencies are not satisfied, or changes in laws affecting project awards occur, or awards are revoked or cancelled, project awards may not convert to contracts, and installations may be delayed or canceled. This could have an adverse impact on our revenue and cash flow and our ability to complete construction of a project.

Our contracted sales are subject to the risk of termination by the contracting party.

The majority of our commercial contracts contain provisions which allow the customer to terminate an agreement if certain conditions are not met or for extended force majeure (which could include inability to perform due to COVID-19). We have issued several force majeure notices to customers as a result of delays caused by COVID-19 and the impact of COVID-19 on such agreements, or the applicable agreements’ termination provisions, is uncertain and could result in the termination of such agreements. In addition, certain of our contracts can be terminated simply for convenience. If a contracted sale were to be terminated, it could have an adverse impact on our revenues, longer term potential and market reputation, which would have an even greater impact on our ability to achieve future sales.

We may not be able to accurately estimate the future supply and demand for our batteries, which could result in a variety of inefficiencies in our business and hinder our ability to generate revenue. If we fail to accurately predict our manufacturing requirements, we could incur additional costs or experience delays.

We are a company with a limited operating history. As we continue the transition from research and development activities to commercial production and sales, it is difficult to predict our future revenues and appropriately budget for our expenses, and we may have limited insight into trends that may emerge and affect our business. We anticipate being required to provide expectations of our demand to our current and future suppliers prior to the scheduled delivery of products to potential customers. Currently, there is no historical basis for making judgments on the demand for our iron flow batteries or our ability to develop, manufacture, and deliver iron flow batteries, or our profitability in the future. If we overestimate our requirements, our suppliers may have excess inventory, which indirectly would increase our costs. If we underestimate our requirements, our suppliers may have inadequate inventory or capacity, which could interrupt manufacturing of our products and result in delays in shipments and revenues. In addition, lead times for materials and components that our suppliers order may vary significantly and depend on factors such as the specific supplier, contract terms and demand for each component at a given time. If we fail to order sufficient quantities of product components in a timely manner, the delivery of batteries to our potential customers could be delayed, which would harm our business, financial condition and results of operations.

If we fail to manage our growth effectively, we may be unable to execute our business plan, maintain high levels of customer service, or adequately address competitive challenges.

We have experienced significant growth in customer contracts in recent periods and intend to continue to expand our business significantly within existing and new markets. This growth has placed, and any future growth may place, a significant strain on our management, operational, and financial infrastructure. In particular, we will be required to expand, train, and manage our growing employee base and scale and otherwise improve our information technology (“IT”) infrastructure in tandem with that headcount growth. Our management will also be required to maintain and expand our relationships with customers, suppliers, and other third parties and attract new customers and suppliers, as well as manage multiple geographic locations.

Our current and planned operations, personnel, customer support, IT, information systems, and other systems and procedures might be inadequate to support future growth and may require us to make additional unanticipated investment in our infrastructure. Our success and ability to scale our business will depend, in part, on our ability to manage these changes in a cost-effective and efficient manner. If we cannot manage our growth, then we may be unable to take advantage of market opportunities, execute our business strategies, or respond to competitive pressures. This could also result in declines in quality or customer satisfaction, increased costs, difficulties in introducing new offerings, or other operational difficulties. Any failure to effectively manage growth could adversely impact our business and reputation.

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We have signed product sales contracts and expect to enter into long-term service agreements with customers subject to contractual, technology, operating and commodity risks as well as market conditions that may affect our operating results.

We expect to enter into long-term service agreements with certain customers to provide service on our energy storage products with terms of up to 25 years. Under the provisions of these contracts, we will provide services to maintain, monitor, and repair our energy storage products to meet minimum operating levels. While we have conducted tests to determine the overall life of our energy storage products, we have not run certain of our energy storage products over their projected useful life or in all potential conditions prior to large scale commercialization. As a result, we cannot be sure that these energy storage products will last to their expected useful life or perform as anticipated in all conditions, which could result in warranty claims, performance penalties, maintenance, on-going servicing and module replacement costs and/or a negative perception of our energy storage products. Our ability to proceed with projects under development and complete construction of projects on schedule and within budget may be adversely affected by escalating costs for materials, tariffs, labor and regulatory compliance, inability to obtain necessary permits, interconnections or other approvals on acceptable terms or on schedule and by other factors. If any development project or construction is not completed, is delayed or is subject to cost overruns, we could become obligated to make delay or termination payments or become obligated for other damages under contracts, experience diminished returns or write off all or a portion of our capitalized costs in the project. Each of these events could have an adverse effect on our business, financial condition and results of operations. We currently face and will continue to face significant competition, including from products using other energy sources that may be lower priced or have preferred environmental characteristics.

We compete on the basis of our energy storage products’ reliability, efficiency, environmental sustainability and cost. Technological advances in alternative energy products, improvements in the electric grid or other sources of power generation, or new battery technologies or market entrants may negatively affect the development or sale of some or all of our energy storage products or make our energy storage products less economically attractive, non-competitive or obsolete prior to or after commercialization. Significant decreases in the price of alternative technologies, or significant increases in the price of the materials we use to build our energy storage products could have a material adverse effect on our business because other generation sources could be more economically attractive to consumers than our energy storage products.

The loss of one or more members of our senior management team, other key personnel or our failure to attract additional qualified personnel may adversely affect our business and our ability to achieve our anticipated level of growth.

We depend on the continued services of our senior management team, including our Chief Executive Officer, President, Chief Technology Officer and Chief Financial Officer, and other key personnel, each of whom would be difficult to replace. The loss of any such personnel, or the inability to effectively transition to their successors, could have a material adverse effect on our business and our ability to implement our business strategy. All of our employees, including our senior management, are free to terminate their employment relationships with us at any time. Any changes to our senior management team, including hires or departures, could cause disruption to our business and have a negative impact on operating performance, while these operational areas are in transition.

Additionally, our ability to attract qualified personnel, including senior management and key technical personnel, is critical to the execution of our growth strategy. Competition for qualified senior management personnel and highly skilled individuals with technical expertise is extremely intense. We face and are likely to continue to face challenges identifying, hiring, and retaining qualified personnel in all areas of our business, and we can provide no assurance that we will find suitable successors as transitions occur. In addition, integrating new employees into our team, and key personnel in particular, could prove disruptive to our operations, require substantial resources and management attention, and ultimately prove unsuccessful. Our failure to attract and retain qualified senior management and other key technical personnel could limit or delay our strategic efforts, which could have a material adverse effect on our business, financial condition and results of operations.

We are highly dependent on the services of Craig Evans, our President and Co-Founder, and Dr. Julia Song, our Chief Technology Officer and Co-Founder, who are married to each other. The separation or divorce of the couple in the future could adversely affect our business.

We are highly dependent on the services of Craig Evans, our President and Co-Founder, and Dr. Julia Song, our Chief Technology Officer and Co-Founder, who are married to each other. If Mr. Evans or Dr. Song were to discontinue their service to us due to death, disability or any other reason, or if they were to become separated or divorced or could otherwise not amicably work with each other, we would be significantly disadvantaged. Alternatively, their work performance may not be satisfactory if they become preoccupied with issues relating to their personal situation. In these cases, our business could be materially harmed.

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Our results of operations may fluctuate from quarter to quarter, which could make our future performance difficult to predict and could cause our results of operations for a particular period to fall below expectations, resulting in a decline in the price of our Common Stock.

Our hardware takes many months to manufacture and prepare for delivery and any revenue in future periods may fluctuate based on underlying customer arrangements. Further, we expect our arrangements may have multiple deliverables and performance obligations and the amount and timing of recognizing revenue for those different performance obligations may vary which could cause our revenue to fluctuate. Our revenues also depend on a number of other factors, some of which are beyond our control, including the impact of supply chain issues (see also “ —Risks Related to Our Technology, Products and Manufacturing—We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products. We also depend on vendors for the shipping of our energy storage products. Continued delays in our supply chain and shipments could further harm our ability to manufacture and commercialize our energy storage products.”). As a result, our quarterly results of operations are difficult to predict and may fluctuate significantly in the future.

We will initially depend on revenue generated from a single product and in the foreseeable future will be significantly dependent on a limited number of products.

We will initially depend on revenue generated initially from our Energy Warehouses and later on, our Energy Centers, and in the foreseeable future will continue to be significantly dependent on a limited number of products. Given that for the foreseeable future our business will depend on a limited number of products, to the extent our products are not well-received by the market, our sales volume, business, financial condition and results of operations would be materially and adversely affected.

Our cost reduction strategy may not succeed or may be significantly delayed, which may result in our inability to achieve profitability.

Our ability to successfully implement our overall business strategy relies on our ability to reduce development and manufacturing costs in the future. Our cost reduction strategy is based on the assumption that increases in production will result in economies of scale. In addition, our cost reduction strategy relies on advancements in our manufacturing process, global competitive sourcing, engineering design, reducing the cost of capital and technology improvements (including stack life and projected power output). Its successful implementation also depends on a number of factors, some of which are beyond our control, including the impact of inflation and the timely delivery of key supplies at reasonable prices. For example, our current supply imbalance may result in additional costs that exceed our current expectations. There is no assurance that our cost reduction strategy will be successful and failure to achieve our cost reduction targets could have a material adverse effect on our business, financial condition and results of operations.

Our planned expansion into new geographic markets or new product lines or services could subject us to additional business, financial, and competitive risks.

We have entered into contracts and other agreements to sell our products in a number of different countries, including the United States, Chile, Spain, Belgium, Slovakia, and Australia. We have in the past, and may in the future, evaluate opportunities to expand into new geographic markets and introduce new product offerings and services that are a natural extension of our existing business. We also may from time to time engage in acquisitions of businesses or product lines with the potential to strengthen our market position, enable us to enter attractive markets, expand our technological capabilities, or provide synergy opportunities.

Our success operating in these new geographic or product markets, or in operating any acquired business, will depend on a number of factors, including our ability to develop solutions to address the requirements of the electric utility industry, renewable energy project developers and owners, and C&I end users, our timely qualification and certification of new products, our ability to manage increased manufacturing capacity and production, and our ability to identify and integrate any acquired businesses.

Further, any additional markets that we may enter could have different characteristics from the markets in which we currently sell products, and our success will depend on our ability to adapt properly to these differences. These differences may include regulatory requirements, including tax laws, trade laws, foreign direct investment review regimes, labor regulations, tariffs, export quotas, customs duties, or other trade restrictions, limited or unfavorable intellectual property protection, international, political or economic conditions, restrictions on the repatriation of earnings, longer sales cycles, warranty expectations, product return policies and cost, performance and compatibility requirements. In addition, expanding into new geographic markets will increase our exposure to presently existing and new risks, such as fluctuations in the value of foreign currencies and difficulties and increased expenses in complying with United States and foreign laws, regulations and trade standards, including the Foreign Corrupt Practices Act of 1977, as amended (the “FCPA”).

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Failure to develop and introduce these new products successfully into the market, to successfully integrate acquired businesses or to otherwise manage the risks and challenges associated with our potential expansion into new product and geographic markets, could adversely affect our revenues and our ability to sustain profitability.

Our business and operations may be adversely affected by outbreaks of contagious diseases and other adverse public health developments.

Any outbreaks of contagious diseases and other adverse public health developments in countries where we and our suppliers operate, could have a material and adverse effect on our business, financial condition and results of operations. These effects could include disruptions to or restrictions on our employees’ ability to travel, as well as temporary closures of our facilities or the facilities of our customers, suppliers, or other vendors in our supply chain. For example, the COVID-19 pandemic resulted in a widespread health crisis that adversely affected, and may continue to adversely affect, the economies and financial markets of many countries, resulting in an economic downturn that could affect demand for our products or our ability to obtain financing for our business or projects.

The outbreak of a pandemic may impact the health of our team members, directors or customers, reduce the availability of our workforce or those of companies with which we do business, or otherwise cause human impacts that may negatively impact our business. Any of these events, which may result in disruptions to our supply chain or customer demand, could materially and adversely affect our business and our financial results. The extent to which such a pandemic would impact our business and our financial results would depend on future developments, which are highly uncertain and cannot be predicted. Such developments may include the geographic spread of the pandemic, the severity of the disease, the duration of the outbreak, the actions that may be taken by various governmental authorities in response to the outbreak, such as quarantine or “shelter-in-place” orders and business closures imposed by various states within the United States, and the impact on the U.S. or global economy. For example, in March 2020, in response to the escalating global COVID-19 outbreak, we temporarily suspended operations at our Wilsonville, Oregon manufacturing facility, and also required those employees that could work from home to do so. While we resumed operations in the manufacturing facility within several weeks, we instituted a split schedule shift, staggered workdays, and significant limitations on various areas of our physical building. These changes all resulted in significant disruption to our business.

In the event of a resurgence of the COVID-19 pandemic, there can be no assurance that any of our facilities will remain open (in full or in part), that our employees that continue to work remotely will return to the office or that our other operations will continue at full or limited capacity. If we again have to shut down production either due to a worsening of the COVID-19 pandemic or the outbreak of a new pandemic, particularly if there were an outbreak in one of our facilities, our project schedules and associated financing could be adversely affected. An extended period of remote working by our employees could strain our technology resources and introduce operational risks, including heightened cybersecurity risk. Further, we have experienced, and may continue to experience, increased costs and expenses, including as a result of (i) conducting periodic “fitness-for-duty” assessments for employees, including symptom checks and providing personal protective equipment, (ii) the expansion of benefits to our employees, including the provision of additional time off for employees who have contracted COVID-19 or are required to be quarantined or who are unable to obtain childcare to return to work, (iii) implementing increased health and safety protocols at all of our facilities, including increased cleaning and sanitization of workspaces, restricting visitor access, mandating social distancing guidelines and increasing the availability of sanitization products, and (iv) the increased cost of personal protective equipment. Taken together, these material impacts to our business caused us to issue several Force Majeure notices for customers anticipating shipments of our product and may result in additional delays in fulfilling customer orders. Although we believe our business is currently considered an “essential” business in our operating markets, if any of the applicable exceptions or exemptions are curtailed or revoked in the future, or any of these exemptions or exceptions do not extend to any of our key suppliers, our business, financial condition and results of operations could be adversely impacted.

While we attempted to continue business development activities during the COVID-19 pandemic, state and local shutdowns, shelter-in-place orders and travel restrictions have impeded our ability to meet with customers and solicit new business, and certain bids and solicitations in which we typically participate were postponed. In addition, our supply chain is heavily dependent on key materials domestically and internationally, including from China. We have seen significant disruptions to key supply chains, shipping times, shipping availability, manufacturing times, and associated costs, both with respect to the sourcing of supplies and the delivery of our products. These disruptions, delays, and increased costs can have a material impact to our business, operations, and financial condition and as a result, at this time, it is impossible to predict the overall impact of COVID-19 or of any other pandemic on our business, liquidity, capital resources, supply chain and financial results or its effect on clean energy demand, capital budgets of our customers, or demand for our products. Additionally, while we have continued to prioritize the health and safety of our team members and customers as we continue to operate during the pandemic, we face an increased risk of litigation related to our operating environments. Even after the COVID-19 pandemic has subsided, we may continue to experience adverse impacts to our business as a result of any economic recession that has occurred or may occur in the future because of the pandemic, or because the pandemic

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worsens again. Additional public health crises could also emerge in the future, including other pandemics or epidemics. Any such public health crisis could pose further risks to us and could also have a material adverse effect on our business, results of operations and financial position.

There may be limitations on the effectiveness of our internal controls, and a failure of our control systems to prevent error or fraud may materially harm our company. We may identify material weaknesses in the future that may cause us to fail to meet our reporting obligations or result in material misstatements of our financial statements. If we fail to remediate any material weaknesses or if we otherwise fail to establish and maintain effective control over financial reporting, our ability to accurately and timely report our financial results could be adversely affected.

In connection with the audits of the financial statements of Legacy ESS for the years ending December 31, 2019 and 2020, we identified two material weaknesses for Legacy ESS due to several deficiencies that were identified in the operating effectiveness of controls over (1) the identification and review of technical issues associated with research and development, raw materials purchase commitments and equity processes which resulted in adjustments to restate the 2019 financial statements and correct the 2020 financial statements; and (2) the review and analysis of certain transactions within Legacy ESS’ financial statement close process. A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting such that there is a reasonable possibility that a material misstatement of our financial statements will not be prevented or detected on a timely basis.

In addition, in preparing STWO’s unaudited condensed consolidated financial statements as of and for the quarterly period ended September 30, 2021, our management concluded that our control around the interpretation and accounting for certain complex features of the Class A ordinary shares and warrants issued by STWO was not effectively designed or maintained. This material weakness resulted in the restatement of STWO’s balance sheet as of September 21, 2020, its annual financial statements for the period ended December 31, 2020 and its interim financial statements for the quarters ended September 30, 2020, March 31, 2021 and June 30, 2021. Additionally, this material weakness could result in a further misstatement of the warrant liability, Class A ordinary shares and related accounts and disclosures that would result in a material misstatement of the financial statements that would not be prevented or detected on a timely basis.

Our management has concluded that these material weaknesses in Legacy ESS’ internal control over financial reporting are due to the fact that, at the time, Legacy ESS was a private company with limited resources and did not have the necessary business processes and related internal controls formally designed and implemented coupled with the appropriate resources with the appropriate level of experience and technical expertise to oversee our business processes and controls. Our management has concluded that the material weaknesses in STWO’s internal control over financial reporting involved difficulty identifying and appropriately applying complex accounting standards and requirements relating to equity and warrants issued in connection with STWO’s initial public offering.

We have determined that we have remediated the material weakness for Legacy ESS related to the identification and review of technical issues associated with research and development, raw materials purchase commitments and equity processes which resulted in adjustments to restate the 2019 financial statements and correct the 2020 financial statements and the material weakness related to STWO as of December 31, 2021. The second material weakness for Legacy ESS related to the operating effectiveness of controls over the review and analysis of certain transactions within ESS’ financial statement close process remains unremediated. Therefore, our principal executive officer and principal financial officer have concluded that the Company’s disclosure controls and procedures were not effective as of December 31, 2021.

We have begun to take steps to remediate the remaining identified unremediated material weakness and enhance our internal controls, and we are planning to do the following:

•We have hired additional personnel and are continuing to expand our team. We are further designing and implementing a formalized internal control framework, including over journal entries and management review controls.

•We are continuing our efforts to improve and strengthen our control processes and procedures to fully remediate these deficiencies. Our management will continue to work with our auditors and other outside advisors to ensure that our controls and procedures are adequate and effective.

We cannot provide any assurances that the measures that we have taken and are planning to take will be sufficient to prevent future material weaknesses from occurring. We also cannot assure you that we have identified all of our existing material weaknesses.

As a public company, we are required to comply with the SEC’s rules implementing Sections 302 and 404 of the Sarbanes-Oxley Act of 2002 (the “Sarbanes-Oxley Act”), which requires management to certify financial and other information in our quarterly and annual reports and to provide an annual management report on the effectiveness of controls over financial reporting (see “Part I Item 4. Controls and Procedures”). When evaluating our internal control over financial reporting, we

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may identify material weaknesses that we may not be able to remediate in time to meet the applicable deadline for compliance with the requirements of Section 404. If we are unable to identify and remediate material weaknesses, it could result in material misstatements to our annual or interim financial statements that might not be prevented or detected on a timely basis or result in delayed filings of required periodic reports. If we are unable to assert that our internal control over financial reporting is effective, investors may lose confidence in the accuracy and completeness of our financial reports, the market price of our Common Stock could be adversely affected and we could become subject to litigation or investigations by the NYSE, the SEC, or other regulatory authorities, which could require additional financial and management resources (see also “—Risks Related to the Business Combination and STWO—We may face litigation and other risks as a result of material weaknesses in our internal control over financial reporting.”).

We will extend product warranties for our energy storage products, which products are complex and could contain defects and may not operate at expected performance levels, which could impact sales and market adoption of our energy storage products, affect our operating results or result in claims against us.

We develop complex and evolving energy storage products and we continue to advance the capabilities of our battery technology, product design and associated manufacturing processes. Our energy storage products are designed primarily to serve the behind-the-meter and front-of-the-meter markets. Our core technology components are incorporated into energy storage products that serve both types of customers.

We will provide an insurance-backed warranty on our energy storage products. We also will provide certain warranties with respect to the energy generation and storage systems we sell, including on their installation, operations and maintenance, and for components not manufactured by us, we generally pass through to our customers the applicable manufacturers’ warranties. As part of our energy generation and storage system contracts, we may provide the customer with performance guarantees that warrant that the underlying system will meet or exceed the minimum energy generation or other energy performance requirements specified in the contract. Under these performance guarantees, we bear the risk of electricity production or other performance shortfalls, even if they result from failures in components from third-party manufacturers. These risks are exacerbated in the event such manufacturers cease operations or fail to honor their warranties.

If our warranty reserves are inadequate to cover future warranty claims on our energy storage products, our financial condition and results of operations may be harmed. Warranty reserves will include our management’s best estimates of the projected costs to repair or to replace items under warranty, which will be based on actual claims incurred and an estimate of the nature, frequency and costs of future claims. Such estimates are inherently uncertain and changes to our historical or projected experience, especially with respect to Energy Warehouse and Energy Center products which are still in development and which we expect to produce at significantly greater volumes than our past products, may cause material changes to our warranty reserves in the future.

We are still gaining field operating experience with respect to our energy storage products, and despite experience gained from trials and pilot testing performed by us, our partners and our suppliers, issues may be found in existing or new energy storage products. This could result in a delay in recognition or loss of revenues, loss of market share or failure to achieve broad market acceptance. The occurrence of defects could also cause us to incur significant warranty, support and repair costs in excess of our estimates, could divert the attention of our engineering personnel from our product development efforts, and could harm our relationships with our customers. Although we seek to limit our liability, a product liability claim brought against us, even if unsuccessful, would likely be time consuming, could be costly to defend, and may hurt our reputation in the marketplace. Our customers could also seek and obtain damages from us for their losses.

Defects or performance problems in our products could result in loss of customers, reputational damage, and decreased revenue, and we may face warranty, indemnity, and product liability claims that may arise from defective products.

We may become subject to product liability claims, even those without merit, which could harm our business, financial condition and results of operations. We face inherent risk of exposure to claims in the event our batteries do not perform as expected or malfunction resulting in personal injury or death. Our risks in this area are particularly pronounced given our S200 batteries have not yet been commercially tested or mass produced. A successful product liability claim against us could require us to pay a substantial monetary award. Moreover, a product liability claim could generate substantial negative publicity about our batteries and business and inhibit or prevent commercialization of other future battery candidates, which would have a material adverse effect on our brand, business, prospects and operating results. Any insurance coverage might not be sufficient to cover all potential product liability claims. Any lawsuit seeking significant monetary damages either in excess of our coverage, or outside of our coverage, may have a material adverse effect on our reputation, business and financial condition. We may not be able to secure additional product liability insurance coverage on commercially acceptable terms or at reasonable costs when needed, particularly if we do face liability for our products and are forced to make a claim under our policy.

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In addition, as we grow our manufacturing volume, the chance of manufacturing defects could increase. We may be unable to correct manufacturing defects or other failures of our battery modules and the products in which they are incorporated, including the Energy Warehouse and Energy Center, in a manner satisfactory to our customers, which could adversely affect customer satisfaction, market acceptance and our business reputation.

Third parties might attempt to gain unauthorized access to our network or seek to compromise our products and services.

Our business is dependent on the security and efficacy of our networks and computer and data management systems. For example, our Energy Warehouses are connected to and controlled and monitored by our centralized remote monitoring service, and we rely on our internal computer networks for many of the systems we use to operate our business generally. From time to time, we may face attempts by others to gain unauthorized access through the Internet or otherwise or to introduce malicious software to our IT systems. We or our products may be a target of computer hackers, organizations or malicious attackers who attempt to:

•gain access to our network or Energy Warehouses or networks of our customers;

•steal proprietary information related to our business, products, employees, and customers; or

•interrupt our systems or those of our customers.

From time to time, we encounter attempts at gaining unauthorized access to our network and we routinely run intrusion checks. To date, none has resulted in any material adverse impact to our business or operations; however, there can be no guarantee that such intrusions will not be material in the future. While we seek to detect and investigate unauthorized attempts and attacks against our network and products of which we become aware, and to prevent their recurrence where practicable through changes to our internal processes and tools and/or changes to our products, we remain potentially vulnerable to additional known or unknown threats. In addition to intentional third-party cyber-security breaches, the integrity and confidentiality of company and customer data and our intellectual property may be compromised as a result of human error, product defects, or technological failures. We utilize third-party contractors to perform certain functions for us, and they face security risks similar to us.

Any failure or perceived failure by us or our service providers to prevent information security breaches or other security incidents or system disruptions, or any compromise of security that results in or is perceived or reported to result in unauthorized access to, or loss, theft, alteration, release or transfer of, our information, or any personal information, confidential information, or other data could result in loss or theft of proprietary or sensitive data and intellectual property, could harm our reputation and competitive position and could expose us to legal claims, regulatory investigations and proceedings, and fines, penalties, and other liability. Any such actual or perceived security breach, security incident or disruption could also divert the efforts of our technical and management personnel, and could require us to incur significant costs and operational consequences in connection with investigating, remediating, eliminating and putting in place additional tools, devices, policies, and other measures designed to prevent actual or perceived security breaches and other incidents and system disruptions, and in, for example, rebuilding internal systems, reduced inventory value, providing modifications to our products and services, defending against claims and litigation, responding to regulatory inquiries or actions, paying damages, or taking other remedial steps with respect to third parties. Moreover, we could be required or otherwise find it appropriate to expend significant capital and other resources to respond to, notify third parties of, and otherwise address the incident or breach and its root cause, and to notify individuals, regulatory authorities and others of security breaches involving certain types of data.

Further, we cannot assure that any limitations of liability provisions in our current or future contracts that may be applicable would be enforceable or adequate or would otherwise protect us from any liabilities or damages with respect to any particular claim relating to a security breach or other security-related matter. We also cannot be sure that our existing insurance coverage will continue to be available on acceptable terms or will be available in sufficient amounts to cover claims related to a security breach or incident, or that the insurer will not deny coverage as to any future claim. The successful assertion of claims against us that exceed available insurance coverage, or the occurrence of changes in our insurance policies, including premium increases or the imposition of large deductible or co-insurance requirements, could have a material adverse effect on our business, including our financial condition, operating results, and reputation.

The failure or breach of our IT systems could affect our sales and operations.

The availability and effectiveness of our energy storage products and our ability to conduct our business and operations, depend on the continued operation of IT and communications systems, some of which we have yet to develop or otherwise obtain the ability to use. Systems used in our business will be vulnerable to damage or interruption. Such systems could also be subject to break-ins, sabotage and intentional acts of vandalism, as well as disruptions and security incidents as a result of non-technical issues, including intentional or inadvertent acts or omissions by employees, service providers, or

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others. We expect to face significant challenges with respect to information security and maintaining the security and integrity of our systems and other systems used in our business, as well as with respect to the data stored on or processed by these systems. We also anticipate storing and otherwise processing confidential business information of ourselves and third parties, as well as personal information and other data. Advances in technology, an increased level of sophistication and expertise of hackers, and new discoveries in the field of cryptography can result in a compromise or breach of the systems used in our business or of security measures used in our business to protect confidential information, personal information, and other data. We may be a target for attacks by state-sponsored actors and others designed to disrupt our operations or to attempt to gain access to our systems or to data that is processed or maintained in our business.

We use outsourced service providers to help provide certain services. For example, we utilize email and collaboration tools, and other third-party services and service providers that store or otherwise process information, including personal information and confidential business information, on our behalf. Any such outsourced service providers face similar security and system disruption risks as us. We are at risk for interruptions, outages and breaches of our and our outsourced vendors’ and service providers’ operational systems and security systems, our products’ and services’ integrated software and technology, and customer data that we or our third-party service providers process. These may be caused by, among other causes, physical theft, viruses or other malicious code, denial or degradation of service attacks, ransomware, social engineering schemes, and insider theft or misuse. While we take steps to review security protections of services provided to us, there can be no guarantee that a failure or breach of such systems will not occur or be perceived to occur. If such failures were to occur, we may not be able to sufficiently recover to avoid the loss of data or any adverse impact on our operations that are dependent on such IT systems. This could result in lost sales as we may not be able to meet the demands for our product, and other harm to our business and results of operations. Further, some of the systems used in our business will not be fully redundant, and our disaster recovery planning cannot account for all eventualities. Any security breaches or incidents or other damage to or disruptions to any data centers or other systems used in our business could result in lengthy interruptions in our service and may adversely affect our business, prospects, financial condition and operating results.

Furthermore, because our IT systems are essential for the exchange of information both internally and in communicating with third parties, including our suppliers and manufacturers, cyber-security breaches could potentially lead to unauthorized acquisition or unauthorized release of sensitive, confidential or personal data or information, improper use of our systems, or, unauthorized access, use, disclosure, modification or destruction of information or defective products. Our IT systems also help us produce financial information. Any disruption or cyber-security breach could impact our ability to produce timely and accurate financial information needed for compliance, audit, and reporting purposes. If any such cyber-security breaches were to continue, our operations and ability to communicate both internally and with third parties may be negatively impacted.

Significant capital and other resources may be required in efforts to protect against information security breaches, security incidents, and system disruptions, or to alleviate problems caused by actual or suspected information security breaches and other security incidents and system disruptions. The resources required may increase over time as the methods used by hackers and others engaged in online criminal activities and otherwise seeking to obtain unauthorized access to systems or data, and to disrupt systems, are increasingly sophisticated and constantly evolving. In addition, laws, regulations, government guidance, and industry standards and practices in the United States and elsewhere are rapidly evolving to combat these threats. We may face increased compliance burdens regarding such requirements with regulators and customers regarding our products and services and also incur additional costs for oversight and monitoring of our supply chain. We also cannot be certain that these systems, networks, and other infrastructure or technology upon which we rely, including those of our third-party suppliers or service providers, will be effectively implemented, maintained or expanded as planned, or will be free from bugs, defects, errors, vulnerabilities, viruses, or malicious code. We may be required to expend significant resources to make corrections or to remediate issues that are identified or to find alternative sources. Any of these circumstances potentially could have a negative impact on our business, prospects, financial condition and operating results.

We may not be able to identify or complete transactions with attractive acquisition candidates. Future acquisitions may result in significant transaction expenses and we may incur significant costs.

We may from time to time selectively pursue on an opportunistic basis acquisitions of additional businesses that complement our existing business and footprint. The success of any such growth strategy would depend, in part, on selecting strategic acquisition candidates at attractive prices and effectively integrating their businesses into our own, including with respect to financial reporting and regulatory matters. There can be no assurance that we will be able to identify attractive acquisition candidates or complete the acquisition of any identified candidates at favorable prices and upon advantageous terms and conditions, including financing alternatives. In addition, general economic conditions or unfavorable capital and credit markets could affect the timing and extent to which we can successfully acquire new businesses, which could limit our revenues and profitability.

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Our facilities or operations could be damaged or adversely affected as a result of natural disasters and other catastrophic events.

Our facilities or operations could be adversely affected by events outside of our control, such as natural disasters, wars, health epidemics such as the ongoing COVID-19 pandemic, and other calamities. We cannot assure you that any backup systems will be adequate to protect our facilities or operations from the effects of fire, floods, typhoons, earthquakes, power loss, telecommunications failures, break-ins, war, riots, terrorist attacks or similar events. Any of the foregoing events may give rise to interruptions, breakdowns, system failures, technology platform failures or internet failures, which could cause the loss or corruption of data or malfunctions of software or hardware as well as adversely affect our ability to provide services.

We may not have sufficient insurance coverage to cover business continuity.

A sustained or repeated interruption in the manufacturing of our products due to labor shortage, fire, flood, war, pandemic, natural disasters and similar unforeseen events beyond our control may interfere with our ability to manufacture our products and fulfil customers’ demands in a timely manner, and make it difficult, or in certain cases, impossible for us to continue our business for a substantial period of time. Failure to manufacture our products and meet customer demands would impair our ability to generate revenues which would adversely affect our financial results. We currently do not have a formal disaster recovery or business continuity plan in place and any disaster recovery and business continuity plans that we may put in place may prove inadequate in the event of a serious disaster or similar event. As part of our risk management, we maintain insurance coverage for our business. However, we cannot assure you that the amounts of insurance will be sufficient to satisfy any damages or losses we may incur. If our insurance coverage is not sufficient, we may incur substantial expenses, which, could have a material adverse effect on our business.

We face risks associated with expanding our international operations, including unfavorable and uncertain regulatory, political, economic, tax and labor conditions.

We are subject to legal and regulatory requirements, political uncertainty and social, environmental and economic conditions in numerous jurisdictions, over which we have little control and which are inherently unpredictable. Our operations in such jurisdictions, particularly as a company based in the United States, create risks relating to conforming our products to regulatory and safety requirements and charging and other electric infrastructures; organizing local operating entities; establishing, staffing and managing foreign business locations; attracting local customers; navigating foreign government taxes, regulations and permit requirements; enforceability of our contractual rights; trade restrictions, foreign direct investment review regimes, customs regulations, tariffs and price or exchange controls; and preferences in foreign nations for domestically manufactured products. Such conditions may increase our costs and tax liabilities, impact our ability to sell our products and require significant management attention, and may harm our business if we are unable to manage them effectively.

Changes in the U.S. trade environment, including the recent imposition of import tariffs, could adversely affect the amount or timing of our revenues, results of operations or cash flows.

We currently procure the injected molded and machined plastic parts as well as cast aluminum parts for our products from China, as we believe that the materials procured from our Chinese suppliers currently have the best overall performance and price compared to domestic alternatives. Escalating trade tensions between the United States and China have recently led to certain increased tariffs and trade restrictions. There can be no guaranty that these developments will not negatively impact the price of the positive electrode used in our products. It is possible we could obtain similar performing materials in the United States, but such sources would likely also charge a higher cost than our current suppliers, which would negatively impact our gross margins. There is no guaranty that we will be able to identify alternate suppliers that meet our quality, volume and price requirements. Failure to meet these requirements could result in supply disruptions and increased costs. It is difficult to predict what further trade-related actions governments may take, which may include additional or increased tariffs and trade restrictions, and we may be unable to react to such actions quickly and effectively, which could result in supply shortages and increased costs.

We could be subject to foreign exchange risk.

Our international sales are expected to be denominated in U.S. dollars. As a result, we will not have significant direct exposure to currency valuation exchange rate fluctuations. However, because our products are sold internationally, to the extent that the U.S. dollar strengthens against the foreign currency of a customer or potential customer, we may find our products at a price disadvantage as compared with other non-U.S. suppliers. This could lead to our receiving lower prices or being unable to compete for that specific customer’s business. Consequently, currency fluctuations could adversely affect the competitiveness of our products in international markets.

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We may be required to take write-downs or write-offs, restructuring and impairment or other charges that could have a significant negative effect on our financial condition, results of operations and stock price, which could cause you to lose some or all of your investment.

Unexpected risks may arise that cause us to write-down or write-off assets, restructure our operations, or incur impairment or other charges that could result in losses. Even though these charges may be non-cash items and not have an immediate impact on our liquidity, the fact that we report charges of this nature could contribute to negative market perceptions about us or our securities. In addition, charges of this nature may cause us to violate net worth or other covenants to which we may be subject. Accordingly, our stockholders could suffer a reduction in the value of their shares.

Our results of operations could vary as a result of changes to our accounting policies or the methods, estimates and judgments we use in applying our accounting policies.

The method estimates and judgments we use in applying our accounting policies have a significant impact on our results of operations. Such methods, estimates and judgments are, by their nature, subject to substantial risks, uncertainties and assumptions, and factors may arise over time that could lead us to reevaluate our methods, estimates and judgments.

In future periods, management will regularly evaluate its estimates such as for service agreements, loss accruals, warranty, performance guarantees, liquidated damages and inventory valuation allowances. Changes in those estimates and judgments could significantly affect our financial condition and results of operations. We will also adopt changes required by the Financial Accounting Standards Board and the SEC.

We have already incurred, and may continue to incur, significant increased expenses and administrative burdens as a public company, which could have a material adverse effect on our business, financial condition and results of operations.

We face increased legal, accounting, administrative and other costs and expenses as a public company that ESS did not incur as a private company prior to the Business Combination. The Sarbanes-Oxley Act, including the requirements of Section 404, as well as rules and regulations subsequently implemented by the SEC, the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 and the rules and regulations promulgated and to be promulgated thereunder, the Public Company Accounting Oversight Board and the securities exchanges impose additional reporting and other obligations on public companies. Compliance with public company requirements is expected to continue to increase costs and make certain activities more time-consuming. A number of those requirements will require us to carry out activities that ESS had not done prior to the Business Combination. For example, we have created new board committees and are adopting new internal controls and disclosure controls and procedures. In addition, additional expenses associated with SEC reporting requirements have been incurred and will continue to be incurred. Furthermore, if any issues in complying with those requirements are identified (for example, if our auditors identify a material weakness or significant deficiency in our internal control over financial reporting), we could incur additional costs rectifying those issues, and the existence of those issues could adversely affect our reputation or investor perceptions of us. It is also more expensive to obtain directors’ and officers’ liability insurance. Risks associated with our status as a public company may make it more difficult to attract and retain qualified persons to serve on our board of directors or as executive officers. The additional reporting and other obligations imposed by these rules and regulations increase legal and financial compliance costs and the costs of related legal, accounting and administrative activities. These increased costs will require us to divert a significant amount of money that could otherwise be used to expand our business and achieve strategic objectives. Advocacy efforts by stockholders and third parties may also prompt additional changes in governance and reporting requirements, which could further increase our costs.

Our management may not successfully or effectively manage our transition to a public company.

Our management team may not successfully or effectively manage our transition to a public company, which transition will be subject to significant regulatory oversight and reporting obligations under federal securities laws. Its limited experience in dealing with the increasingly complex laws pertaining to public companies could be a significant disadvantage in that it is likely that an increasing amount of management’s time may be devoted to these activities which will result in less time being devoted to our management and growth. We may not have adequate personnel with the appropriate level of knowledge, experience and training in the accounting policies, practices or internal controls over financial reporting required of public companies in the United States. The development and implementation of the standards and controls necessary for us to achieve the level of accounting standards required of a public company in the United States may require costs greater than expected. It is possible that we will be required to expand our employee base and hire additional employees to support our operations as a public company which will increase our operating costs in future periods.

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We may engage in transactions with related parties and such transactions present possible conflicts of interest that could have an adverse effect on us.

We may enter into transactions with related parties. Related-party transactions create the possibility of conflicts of interest with regard to our management, including that:

•we may enter into contracts between us, on the one hand, and related parties, on the other, that are not as a result of arm’s-length transactions;

•our executive officers and directors that hold positions of responsibility with related parties may be aware of certain business opportunities that are appropriate for presentation to us as well as to such other related parties and may present such business opportunities to such other parties; and

•our executive officers and directors that hold positions of responsibility with related parties may have significant duties with, and spend significant time serving, other entities and may have conflicts of interest in allocating time.

Such conflicts could cause an individual in our management to seek to advance his or her economic interests or the economic interests of certain related parties above ours. Further, the appearance of conflicts of interest created by related-party transactions could impair the confidence of our investors. Our board of directors regularly reviews these transactions. Notwithstanding this, it is possible that a conflict of interest could have a material adverse effect on our business, financial condition and results of operations.

Risks Related to Regulatory, Environmental and Legal Issues

We may face regulatory challenges to or limitations on our ability to sell our Energy Centers and Energy Warehouses directly in certain markets. Expanding operations internationally could expose us to additional risks.

While we intend to continue to sell our products across the United States both directly and through third parties, our ability to continue such sales may be affected by future limitations, either directly to the ability to sell energy storage or by broader regulation related to the sales and operation of distributed energy resources, which could have an impact on our ability to sell our products to the market.

Although we currently primarily operate in the United States, we continue to expand our business internationally. Any expansion internationally could subject our business to risks associated with international operations. In addition, there may be laws in international jurisdictions we have not yet entered or laws we are unaware of in jurisdictions we have entered that may restrict our sales or other business practices. Even for those jurisdictions we have analyzed, the laws in this area can be complex, difficult to interpret and may change over time. Continued regulatory limitations and other obstacles interfering with our ability to sell our energy storage products may harm our business, financial condition and results of operations. Additionally, any regulation that affects the sale or operations of distributed energy resources could diminish the real or perceived value of our energy storage solutions in those markets. As a result of these risks, any potential future international expansion efforts that we may undertake may not be successful.

Our customers may be required to obtain environmental, health and safety or other certifications in order to install our products. If our customers are unable to obtain the necessary certifications, we will not be able to install our products, which would negatively impact our revenues.

While our engineering team has worked closely with the CSA Group, Intertek, UL and Technischer Überwachungsverein certification agencies to obtain certifications of our flow battery products against all applicable safety standards, there is no guarantee that such certifications shall continue to be obtained. From our prior certifications, we have expanded our flow battery product certification to the European Conformity marking in the European Union and intend to expand to other national standards such as the international certification of the International Electrotechnical Commission (“IEC”). Failure to obtain IEC certification may have impact on our revenues, as such certifications are required by some of our customers.

We are subject to multiple U.S. federal, state and local regulations. Changes in applicable law, regulations or requirements, or our material failure to comply with any of them, can increase our costs and have other negative impacts on our business.

Applicable laws and requirements address multiple aspects of our operations, such as worker safety, consumer rights, privacy, cybersecurity, employee benefits and more, and can often have different requirements in different jurisdictions. Changes in these requirements, or any material failure to comply with them, could increase our costs, affect our reputation, result in claims, litigation, and regulatory investigations or other proceedings, which may result in fines, penalties, and other liabilities, and which may limit our business, drain management’s time and attention or otherwise, and generally impact our operations in adverse ways.

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We are subject to requirements relating to environmental and safety regulations and environmental remediation matters which could adversely affect our business, results of operation and reputation.

We are subject to numerous federal, state and local environmental laws and regulations governing, among other things, solid and hazardous waste storage, treatment and disposal, and remediation of releases of hazardous materials. There are significant capital, operating and other costs associated with compliance with these environmental laws and regulations. Environmental laws and regulations may become more stringent in the future, which could increase costs of compliance or require us to manufacture with alternative technologies and materials.

Federal, state and local authorities also regulate a variety of matters, including, but not limited to, health, safety and permitting in addition to the environmental matters discussed above. New legislation and regulations may require us to make material changes to our operations, resulting in significant increases to the cost of production.

Our manufacturing process will have hazards such as but not limited to hazardous materials, machines with moving parts, and high voltage and/or high current electrical systems typical of large manufacturing equipment and related safety incidents. There may be safety incidents that damage machinery or product, slow or stop production, or harm employees. Consequences may include litigation, regulation, fines, increased insurance premiums, mandates to temporarily halt production, workers’ compensation claims, or other actions that impact our company brand, finances, or ability to operate.

We may be exposed to delays, limitations and risks related to the environmental permits and other operating permits required to operate our products.

Operation of our manufacturing facilities requires land use and environmental permits and other operating permits from federal, state and local government entities. While we have all permits necessary to carry out and perform our current plans and operations at our existing facility, we may require additional environmental, wastewater and land use permits for the commercial operation of any future manufacturing facilities. Delays, denials or restrictions on any of the applications for or assignment of the permits to operate our manufacturing facilities could adversely affect our ability to execute on our business plans and objectives.

We may collect and process certain information about our customers and about individuals and will be subject to various laws and regulations relating to privacy, data protection and cybersecurity.

We may collect and process certain battery data required for performance monitoring, safety and serviceability. This information is transmitted to our control center and stored. Such data currently is limited to battery operational and safety parameters. Additionally, we collect and otherwise process other data relating to individuals, including business partners, prospects, employees, vendors, and contractors. Our handling of data relating to individuals is subject to a variety of laws and regulations relating to privacy, data protection and cybersecurity, and we may become subject to additional obligations, including contractual obligations, relating to our maintenance and other processing of this data, and new or modified laws or regulations. Laws, regulations, and other actual and potential obligations relating to privacy, data protection, and cybersecurity are evolving rapidly, and we expect to potentially be subject to new laws and regulations, or new interpretations of laws and regulations, in the future in various jurisdictions. These laws, regulations, and other obligations, and changes in their interpretation, could require us to modify our operations and practices, restrict our activities, and increase our costs. Further, these laws, regulations, and other obligations are complex and compliance with them can be difficult. It is possible that these laws, regulations, and other obligations may be inconsistent with one another or be interpreted or asserted to be inconsistent with our business or practices. We anticipate needing to dedicate substantial resources to comply with laws, regulations, and other obligations relating to privacy and cybersecurity in order to comply. Any actual or alleged failure by us to comply with our privacy policy or any federal, state or international privacy, data protection or security laws or regulations or other obligations could result in claims and litigation against us, regulatory investigations and other proceedings, legal liability, fines, damages and other costs. Any actual or alleged failure by any of our vendors or business partners to comply with contractual or legal obligations regarding the protection of information about our customers could carry similar consequences. Should we become subject to additional privacy or data protection laws, regulations, or other obligations relating to privacy, data protection or cybersecurity, we may need to undertake compliance efforts that could carry a large cost and could entail substantial time and other resources.

Further, although we take steps to protect the security of our customers’ personal information and other personal information within our control, we may face actual or perceived breaches of security, security incidents, or other misuses of this information, and many jurisdictions have enacted laws requiring companies to notify individuals, regulatory authorities and others of security breaches involving certain types of data. We may be required to expend significant resources to comply with security breach and security incident notification requirements if a third party accesses or acquires such personal information without authorization, if we otherwise experience a security breach or incident or loss or damage of personal information, or if this is perceived to have occurred. Any actual or perceived breach of our network security or systems, or those of our vendors or service providers, could result in claims, litigation, and proceedings against us by

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governmental entities or others, have negative effects on our business and future prospects, including possible fines, penalties and damages, and could result in reduced demand for our energy storage products and harm to our reputation and brand, resulting in negative impacts to our business, prospects, and financial results.

We could be subject to penalties and other adverse consequences for any violations of the FCPA, and other foreign anti-bribery and anti-corruption laws.

We are subject to the FCPA, the U.S. domestic bribery statute contained in 18 U.S.C. § 201, the United Kingdom Bribery Act 2010, and possibly other anti-bribery and anti-corruption laws in countries outside of the United States in which we conduct our activities. We may have business dealings with customers in certain countries that are high risk for corruption. Anti-corruption and anti-bribery laws have been enforced aggressively in recent years and are interpreted broadly to generally prohibit companies and their employees, agents, representatives, business partners, and third-party intermediaries from authorizing, offering, or providing, directly or indirectly, improper payments or benefits to recipients in the public or private sector.

We sometimes leverage third parties to sell our products and conduct our business abroad. We, our employees, agents, representatives, business partners or third-party intermediaries may have direct or indirect interactions with officials and employees of government agencies or state-owned or affiliated entities and may be held liable for the corrupt or other illegal activities of these employees, agents, representatives, business partners or third-party intermediaries even if we do not explicitly authorize such activities. We cannot assure you that all of our employees and agents will not take actions in violation of applicable law, for which we may be ultimately held responsible. We currently have contracts and may potentially operate in parts of the world that have experienced higher levels of governmental corruption and as we increase our international sales and business, our risks under these laws may increase. In addition, due to the level of regulation in our industry and related energy industries, our entry into certain jurisdictions may require substantial government contact where norms can differ from U.S. standards.

These laws also require that we keep accurate books and records and maintain internal controls and compliance procedures designed to prevent any such actions. While we have policies and procedures to address and to mandate compliance with such laws, we cannot assure you that none of our employees, agents, representatives, business partners or third-party intermediaries will take actions in violation of our policies and applicable law, for which we may be ultimately held responsible.

In the event that we believe, have reason to believe, or are notified that our employees, agents, representatives, business partners, or third party intermediaries have or may have violated applicable laws, including anti-bribery and anti-corruption laws, we may be required to investigate or have outside counsel investigate the relevant facts and circumstances, and detecting, investigating and resolving actual or alleged violations can be expensive and require significant time and attention from senior management. Any allegation or violation of U.S. federal and state and non-U.S. laws, regulations and policies regarding anti-bribery and anti-corruption could result in substantial fines, sanctions, civil and/or criminal penalties, whistleblower complaints, sanctions, settlements, prosecution, enforcement actions, damages, adverse media coverage, investigations, loss of export privileges, suspension or debarment from government contracts, or other curtailment of operations in the United States or other applicable jurisdictions. In addition, actual or alleged violations could damage our reputation and ability to do business. Any of the foregoing could materially adversely affect our reputation, business, financial condition, prospects and results of operations.

We are subject to governmental export and import controls and economic sanctions programs that could impair our ability to compete in international markets or subject us to liability if we violate these controls.

Our products and services are, or may in the future be, subject to U.S. export control laws and regulations including the Export Administration Regulations (“EAR”) and trade and economic sanctions maintained by the Office of Foreign Assets Control (“OFAC”) and to similar laws and regulations in all other jurisdictions in which we operate. As such, an export license may be required to export, re-export or transfer our products and services to certain countries or end-users or for certain end-uses. If we were to fail to comply with such export control laws and regulations or trade and economic sanctions, we could be subject to both civil and criminal penalties, including substantial fines, possible incarceration for employees and managers for willful violations, and the possible loss of our export and/or import privileges. Compliance with the EAR, OFAC sanctions, and other applicable regulatory requirements regarding the import and export of our products or the performance of services, may create delays in the introduction of our products and services in non-U.S. markets, prevent our customers with non-U.S. operations from deploying these products and services throughout their global systems or, in some cases, prevent the export of the products and services to some countries or users altogether. We may enter into agreements with customers and counterparties located in countries subject to list-based OFAC sanctions.

Obtaining the necessary export license for a particular sale or offering may not be possible, may be time-consuming, and may result in the delay or loss of sales opportunities. Further, U.S. export control laws and trade and economic sanctions as

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well as similar laws and regulations in other jurisdictions prohibit the export of products and services to certain U.S. embargoed or sanctioned countries, governments, and persons, as well as for prohibited end-uses. Even though we have taken precautions to ensure that we and our partners comply with all relevant import and export control laws and regulations and sanctions, monitoring and ensuring compliance with these complex laws and regulations is particularly challenging, and any failure by us or our partners to comply with such laws and regulations could have negative consequences for us, including reputational harm, government investigations and penalties.

Any change in domestic or international export or import laws or regulations, economic sanctions, or related legislation, shift in the enforcement or scope of existing export, import, or sanctions laws or regulations, or change in the countries, governments, persons, or technologies targeted by such export, import, or sanctions laws or regulations, could result in decreased use of our products and/or services by, or in our decreased ability to export or sell our products and/or services to, end-customers with international operations.

We may be exposed to various risks related to legal proceedings or claims that could adversely affect our operating results. The nature of our business exposes us to various liability claims, which may exceed the level of our insurance coverage resulting in our not being fully protected.

We have been and may continue to be party to lawsuits in the normal course of our business. Litigation can be expensive, lengthy and disruptive to normal business operations. Moreover, the results of complex legal proceedings are difficult to predict. Responding to lawsuits brought against us, or legal actions that we may initiate, can be expensive and time-consuming. Unfavorable outcomes from these claims and/or lawsuits could adversely affect our business, financial condition or results of operations, and we could incur substantial monetary liability and/or be required to change our business practices.

Our business may expose us to claims for personal injury, death or property damage resulting from the use of our products or from employee related matters. Additionally, we could be subject to potential litigation associated with compliance with various laws and governmental regulations at the federal, state or local levels, such as those relating to the protection of persons with disabilities, employment, health, safety, security and other regulations under which we operate.

We carry comprehensive insurance, subject to deductibles, at levels we believe are sufficient to cover existing and future claims made during the respective policy periods. However, we may be exposed to multiple claims, and, as a result, could incur significant out-of-pocket costs before reaching the deductible amount, which could adversely affect our financial condition and results of operations. In addition, the cost of such insurance policies may increase significantly upon renewal of those policies as a result of general rate increases for the type of insurance we carry as well as our historical experience and experience in our industry. Although we have not experienced any material losses that were not covered by insurance, our existing or future claims may exceed the coverage level of our insurance, and such insurance may not continue to be available on economically reasonable terms, or at all. If we are required to pay significantly higher premiums for insurance, are not able to maintain insurance coverage at affordable rates or must pay amounts in excess of claims covered by our insurance, then we could experience higher costs that could adversely affect our financial condition and results of operations.

The reduction, elimination or expiration of government tax credits, subsidies and economic incentives related to renewable energy solutions could reduce demand for our technology and harm our business.

The U.S. federal government and some state and local governments provide incentives to end users and potential purchasers of our energy storage products in the form of rebates, tax credits and other financial incentives, such as system performance payments and payments for renewable energy credits associated with renewable energy generation. We will rely on these governmental rebates, tax credits and other financial incentives to significantly lower the effective price of the energy storage products to our customers in the United States. However, these incentives may expire on a particular date, end when the allocated funding is exhausted, or be reduced or terminated as a matter of regulatory or legislative policy.

Our energy storage products have qualified for tax exemptions, incentives or other customer incentives in many states including California. Some states have utility procurement programs and/or renewable portfolio standards for which our technology is eligible. There is no guarantee that these policies will continue to exist in their current form, or at all. Such state programs may face increased opposition on the U.S. federal, state and local levels in the future. Changes in federal or state programs could reduce demand for our energy storage products, impair sales financing and adversely impact our business results.

We are an emerging growth company and a smaller reporting company within the meaning of the Securities Act, and if we take advantage of certain exemptions from disclosure requirements available to “emerging growth companies” or

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“smaller reporting companies,” this could make our securities less attractive to investors and may make it more difficult to compare our performance with other public companies.

We are an “emerging growth company” within the meaning of the Securities Act, as modified by the JOBS Act, and we may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not “emerging growth companies” including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act, reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved. As a result, our shareholders may not have access to certain information they may deem important. We could be an emerging growth company for up to five years from the STWO IPO, although circumstances could cause us to lose that status earlier, including if the market value of the Common Stock held by non-affiliates exceeds $700,000,000 as of any June 30 before that time, in which case we would no longer be an emerging growth company as of the following December 31. We cannot predict whether investors will find our securities less attractive because we expect to rely on these exemptions. If some investors find our Common Stock less attractive as a result of our reliance on these exemptions, the trading price of our Common Stock may be lower than it otherwise would be, there may be a less active trading market for our Common Stock and the trading price of our Common Stock may be more volatile.

Further, Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that a company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such an election to opt out is irrevocable. We have elected not to opt out of such extended transition period which means that when a standard is issued or revised and it has different application dates for public or private companies, we, as an emerging growth company, can adopt the new or revised standard at the time private companies adopt the new or revised standard. This may make comparison of our financial statements with another public company which is neither an emerging growth company nor an emerging growth company which has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used.

Additionally, we are currently a “smaller reporting company” as defined in Item 10(f)(1) of Regulation S-K. Smaller reporting companies may take advantage of certain reduced disclosure obligations, including, among other things, providing only two years of audited financial statements. We will remain a smaller reporting company only until the last day of the fiscal year in which (i) the market value of the Common Stock held by non-affiliates exceeds $250,000,000 as of the prior June 30, or (ii) our annual revenues exceeded $100,000,000 during such completed fiscal year and the market value of the Common Stock held by non-affiliates exceeds $700,000,000 as of the prior June 30. To the extent we take advantage of such reduced disclosure obligations, it may also make comparison of our financial statements with other public companies difficult or impossible.

We are subject to changing laws and regulations regarding regulatory matters, corporate governance and public disclosure that have increased both our costs and the risk of non-compliance.

We are subject to rules and regulations by various governing bodies, including, for example, the SEC, which are charged with the protection of investors and the oversight of companies whose securities are publicly traded, and to new and evolving regulatory measures under applicable law. Our efforts to comply with new and changing laws and regulations have resulted in increased general and administrative expenses and a diversion of management time and attention.

Moreover, because these laws, regulations and standards are subject to varying interpretations, their application in practice may evolve over time as new guidance becomes available. This evolution may result in continuing uncertainty regarding compliance matters and additional costs necessitated by ongoing revisions to our disclosure and governance practices. If we fail to address and comply with these regulations and any subsequent changes, we may be subject to penalty and our business may be harmed.

Changes in tax laws or in their implementation or interpretation may adversely affect our business and financial condition.

We are or may become subject to income- and non-income-based taxes in the United States under federal, state and local jurisdictions and in certain foreign jurisdictions in which we operate. Tax laws, regulations and administrative practices in these jurisdictions may be subject to significant change, with or without advance notice. For example, the U.S. House of Representatives has proposed numerous changes to U.S. federal income tax law, including modifications of the provisions addressing taxation of international business operations and the imposition of a global minimum tax. Such changes, if enacted, may adversely affect our effective tax rates, cash flows and general business condition.

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Risks Related to Our Intellectual Property

If we fail to protect, or incur significant costs in defending, our intellectual property and other proprietary rights, then our business and results of operations could be materially harmed.

Our success depends to a significant degree on our ability to protect our intellectual property and other proprietary rights. We rely on a combination of patent, trademark, copyright, trade secret, and unfair competition laws, as well as confidentiality and other contractual provisions with our customers, suppliers, employees, and others, to establish and protect our intellectual property and other proprietary rights. Our ability to enforce these rights is subject to general litigation risks, as well as uncertainty as to the enforceability of our intellectual property rights in various countries. When we seek to enforce our rights, we may be subject to claims that our intellectual property rights are invalid or not enforceable. Our assertion of intellectual property rights may result in another party seeking to assert claims against us, which could harm our business. Our inability to enforce intellectual property rights under any of these circumstances would likely harm our competitive position and business.

We have applied for patents in the United States, Europe, Australia, and under the Patent Cooperation Treaty, some of which have been issued. We cannot guarantee that any of our pending applications will be approved or that our existing and future intellectual property rights will be sufficiently broad to protect our proprietary technology, and any failure to obtain such approvals or finding that our intellectual property rights are invalid or unenforceable could force us to, among other things, rebrand or re-design our affected products. In countries where we have not applied for patent protection or where effective intellectual property protection is not available to the same extent as in the United States, we may be at greater risk that our proprietary rights will be misappropriated, infringed, or otherwise violated. Government actions may also undermine our intellectual property rights.

Our intellectual property may be stolen or infringed upon. In the event of such theft or infringement, we may be required to initiate lawsuits to protect our significant investment in our intellectual property. So far, we have been neither the subject of any lawsuits challenging the ownership or validity of our intellectual property, nor have we been required to initiate any lawsuits to protect our intellectual property. However, any such lawsuits may consume management and financial resources for long periods of time and may not result in outcomes that are favorable or readily enforceable, which may adversely affect our business, financial condition or results of operations.

Third parties may assert that we are infringing upon their intellectual property rights, which could divert management’s attention, cause us to incur significant costs, and prevent us from selling or using the technology to which such rights relate.

Our competitors and other third parties hold numerous patents related to technology used in our industry. From time to time, we may also be subject to claims of intellectual property right infringement and related litigation, and, if we gain greater recognition in the market, we will face a higher risk of being the subject of claims that we have violated others’ intellectual property rights. While we believe that our products and technology do not infringe in any material respect upon any valid intellectual property rights of third parties, we cannot be certain that we would be successful in defending against any such claims. If we do not successfully defend or settle an intellectual property claim, we could be liable for significant monetary damages and could be prohibited from continuing to use certain technology, business methods, content, or brands. To avoid a prohibition, we could seek a license from the applicable third party, which could require us to pay significant royalties, increasing our operating expenses. If a license is not available at all or not available on reasonable terms, then we may be required to develop or license a non-violating alternative, either of which could require significant effort and expense. If we cannot license or develop a non-violating alternative, we would be forced to limit or stop sales of our offerings and may be unable to effectively compete. Any of these results would adversely affect our business, financial condition and results of operations.

Our patent applications may not result in issued patents or our patent rights may be contested, circumvented, invalidated or limited in scope, any of which could have a material adverse effect on our ability to prevent others from interfering with the commercialization of our products.

Our patent applications may not result in issued patents, which may have a material adverse effect on our ability to prevent others from commercially exploiting products similar to ours. The status of patents involves complex legal and factual questions and the breadth of claims allowed is uncertain. As a result, we cannot be certain that the patent applications that we file will result in patents being issued, or that our patents and any patents that may be issued to us will afford protection against competitors with similar technology. Numerous patents and pending patent applications owned by others exist in the fields in which we have developed and are developing our technology. In addition to those who may claim priority, any of our existing or pending patents may also be challenged by others on the basis that they are otherwise invalid or unenforceable. Furthermore, patent applications filed in foreign countries are subject to laws, rules and procedures that

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differ from those of the United States, and thus we cannot be certain that foreign patent applications related to issued U.S. patents will be issued.

Even if our patent applications succeed and we are issued patents in accordance with them, we are still uncertain whether these patents will be contested, circumvented, invalidated or limited in scope in the future. The rights granted under any issued patents may not provide us with meaningful protection or competitive advantages, and some foreign countries provide significantly less effective patent enforcement than in the United States. In addition, the claims under any patents that issue from our patent applications may not be broad enough to prevent others from developing technologies that are similar or that achieve results similar to ours. The intellectual property rights of others could also bar us from licensing and exploiting any patents that issue from our pending applications. In addition, patents issued to us may be infringed upon or designed around by others and others may obtain patents that we need to license or design around, either of which would increase costs and may adversely affect our business, financial condition and results of operations.

Risks Related to Our Indebtedness

As we endeavor to expand our business, we will incur significant costs and expenses, which could outpace our cash reserves. Unfavorable conditions or disruptions in the capital and credit markets may adversely impact business conditions and the availability of credit.

We expect to incur additional costs and expenses in the future related to the continued development and expansion of our business, including in connection with expanding our manufacturing capabilities to significantly increase production capacity, developing our products, maintaining and enhancing our research and development operations, expanding our sales, marketing, and business development activities in the United States and internationally, and growing our project management, field services and overall operational capabilities for delivering projects. We do not know whether our revenues will grow rapidly enough to absorb these costs or the extent of these expenses or their impact on our results of operations.

Disruptions in the global capital and credit markets as a result of an economic downturn, economic uncertainty, changing or increased regulation, or failures of significant financial institutions, as well as any negative perceptions about our long-term business prospects or the renewable energy sector as a whole, even if exaggerated or unfounded, could adversely affect our customers’ ability to access capital and could adversely affect our access to liquidity needed for business in the future. Our business could be hurt if we are unable to obtain additional capital as required, resulting in a decrease in our revenues and profitability.

We may need additional capital in the future, and it may not be available on acceptable terms, if at all.

We may need to access the debt and equity capital markets. However, these sources of financing may not be available on acceptable terms, or at all. Our ability to obtain additional financing will be subject to a number of factors, including market conditions, our operating performance, investor sentiment generally or about the renewable energy sector specifically and our ability to incur additional debt in compliance with agreements governing our then-outstanding debt. These factors may make the timing, amount, terms or conditions of additional financings unattractive to us. If we raise additional funds by issuing equity, equity-linked or debt securities, those securities may have rights, preferences or privileges senior to the rights of our currently issued and outstanding equity or debt, and our existing stockholders may experience dilution. If we are unable to generate sufficient funds from operations or raise additional capital, our successful operation and growth could be impeded.

We are subject to certain restrictions and obligations on our business as a result of grants and/or loans received under certain governmental programs and we may be subject to similar or other restrictions to the extent we utilize governmental grants in the future.

Some of our research has been funded by grants from U.S. government agencies. In conjunction with the Advanced Research Projects Agency-Energy grant we received from the Department of Energy, we granted to the United States a non-exclusive, nontransferable, irrevocable, paid-up license to practice or have practiced for or on behalf of the United States inventions related to iron flow technology and made within the scope of the grant. When new technologies are developed with U.S. government funding, the government obtains certain rights in any resulting patents and technical data, generally including, at a minimum, a nonexclusive license authorizing the government to use the invention or technical data for noncommercial purposes. U.S. government funding must be disclosed in any resulting patent applications, and our rights in such inventions will normally be subject to government license rights, periodic progress reporting, foreign manufacturing restrictions and march-in rights. Therefore, if we failed to disclose to the Department of Energy an invention made with grant funds that we disclosed to patent counsel or for publication, or if we elect not to retain title to the invention, the United States may request that title to the subject invention be transferred to it.

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March-in rights refer to the right of the U.S. government, under certain limited circumstances, to require us to grant a license to technology developed under a government grant to a responsible applicant or, if we refuse, to grant such a license itself. March-in rights can be triggered if the government determines that we have failed to work sufficiently towards achieving practical application of a technology or if action is necessary to alleviate health or safety needs, to meet requirements of federal regulations or to give preference to U.S. industry. If we breach the terms of our grants, the government may gain rights to the intellectual property developed in our related research. The government’s rights in our intellectual property may lessen its commercial value, which could adversely affect our performance.

To the extent we utilize governmental grants in the future, the governmental entities involved may retain certain rights in technology that we develop using such grant money. These rights could restrict our ability to fully capitalize upon the value of this research by reducing total revenues that might otherwise be available since such governmental rights may give the government the right to practice the invention without payment of royalties if we do not comply with applicable requirements. Such grants and other forms of government incentives may also subject us to additional disclosure or reporting requirements.

Risks Related to the Business Combination and STWO

We may face litigation and other risks as a result of material weaknesses in our internal control over financial reporting.

On April 12, 2021, the staff of the SEC issued a public statement entitled “Staff Statement on Accounting and Reporting Considerations for Warrants issued by Special Purpose Acquisition Companies” (the “SEC Staff Statement”). Following the issuance of the SEC Staff Statement, after consultation with Marcum LLP (“Marcum”), STWO’s independent registered public accounting firm, our management and the audit committee of our board of directors (the “Audit Committee”) concluded that it was appropriate to restate the previously issued audited financial statements of STWO as of December 31, 2020 and for the period from STWO’s inception through December 31, 2020.

In preparing STWO’s unaudited condensed consolidated financial statements as of and for the quarterly period ended September 30, 2021, we have re-evaluated STWO’s application of ASC 480-10-S99-3A to its accounting classification of its outstanding Class A ordinary shares, par value $0.0001 per share (the “Public Shares”), issued as part of the units sold in the STWO IPO on September 21, 2020. Historically, a portion of the Public Shares was classified as permanent equity to maintain shareholders’ equity greater than $5 million on the basis that STWO would not redeem its Public Shares in an amount that would cause its net tangible assets to be less than $5,000,001, as described in STWO’s memorandum and articles of association (the “Charter”). Pursuant to such reevaluation, our management has determined that the Public Shares included certain provisions that require classification of all of the Public Shares as temporary equity regardless of the net tangible assets redemption limitation contained in the Charter. In addition, in connection with the change in presentation for the Public Shares, we determined we should restate STWO’s earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a business combination as the most likely outcome, in which case, both classes of shares share pro rata in the income and losses of STWO.

Therefore, on November 22, 2021, our management and Audit Committee concluded that STWO’s previously issued (i) audited balance sheet as of September 21, 2020, as previously restated in STWO’s Annual Report on Form 10-K, as amended, for the fiscal year ended December 31, 2020, filed with the SEC on May 13, 2021 (the “2020 Form 10-K/A No. 1”), (ii) audited financial statements included in the 2020 Form 10-K/A No. 1, (iii) unaudited interim financial statements included in the Form 10-Q for the quarterly period ended September 30, 2020 as previously restated in the 2020 Form 10-K/A No. 1; (iv) unaudited interim financial statements included in STWOs Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2021, filed with the SEC on May 13, 2021; and (v) unaudited interim financial statements included in STWO’s Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2021, filed with the SEC on August 11, 2021 (collectively, the “Affected Periods”), should be restated to report all Public Shares as temporary equity and should no longer be relied upon.

As such, we restated STWO’s financial statements for the Affected Periods in our second amended annual report on Form 10-K/A filed with the SEC on December 3, 2021, our first amended quarterly report on Form 10-Q/A for the period ended March 31, 2021 and our first amended quarterly report on Form 10-Q/A for the period ended June 30, 2021, each filed with the SEC on December 6, 2021, and our Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2021, filed with the SEC on November 22, 2021.

As part of the restatements, we identified material weaknesses in our internal controls over financial reporting. As a result of these material weaknesses, the restatements, the change in accounting for the warrants, the reclassification of Class A ordinary shares, and other matters raised or that may in the future be raised by the SEC, we face potential for litigation or other disputes which may include, among others, claims invoking the federal and state securities laws, contractual claims or

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other claims arising from the restatements and material weaknesses in our internal control over financial reporting and the preparation of our financial statements. As of the date of this Quarterly Report on Form 10-Q, we have no knowledge of any such litigation or dispute. However, we can provide no assurance that such litigation or dispute will not arise in the future. Any such litigation or dispute, whether successful or not, could have a material adverse effect on our business, results of operations and financial condition.

Risks Related to our Common Stock and Warrants

The price of our Common Stock may be volatile.

The price of our Common Stock may fluctuate due to a variety of factors, including:

•changes in the industries in which we and our customers operate;

•variations in our operating performance and the performance of our competitors in general;

•material and adverse impact of the COVID-19 pandemic on the markets and the broader global economy;

•actual or anticipated fluctuations in our quarterly or annual operating results;

•the public’s reaction to our press releases, our other public announcements and our filings with the SEC;

•our failure or the failure of our competitors to meet analysts’ projections or guidance that we or our competitors may give to the market;

•additions and departures of key personnel;

•changes in laws and regulations affecting our business;

•commencement of, or involvement in, litigation involving us;

•changes in our capital structure, such as future issuances of securities or the incurrence of additional debt;

•publication of research reports by securities analysts about us or our competitors or our industry;

•sales of shares of our Common Stock by our existing stockholders;

•the volume of shares of our Common Stock available for public sale; and

•general economic and political conditions such as recessions, interest rates, fuel prices, foreign currency fluctuations, international tariffs, social, political and economic risks, hostilities or the perception that hostilities may be imminent, military conflict and acts of war, including an escalation of the situation in the Ukraine and the related response, including sanctions or other restrictive actions, by the United States and/or other countries or terrorism.

These market and industry factors may materially reduce the market price of our Common Stock regardless of our operating performance.

In addition, we have been and in the future may again be the subject of a report issued by activist short sellers. Any such report, even if it contains false and misleading statements about our company, may cause our stock price to experience volatility.

A sale of a significant portion of our total outstanding shares into the market may cause the market price of our Common Stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our Common Stock in the public market could occur at any time. These sales, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our Common Stock.

On December 15, 2021, we filed a registration statement to register shares reserved for future issuance under our equity compensation plans. Pursuant to that registration statement, subject to the satisfaction of applicable vesting restrictions, the shares issued upon exercise of outstanding stock options will be available for immediate resale in the public market.

Certain holders of shares of our common stock have rights, subject to certain conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. Registration of these shares under the Securities Act would result in the shares becoming freely tradeable in the public market, subject to the restrictions of Rule 144 in the case of our affiliates. Any sales of securities by these stockholders could have a material adverse effect on the market price for our common stock. Sales of our Common Stock pursuant to the exercise of registration rights may make it more difficult for us to sell equity securities in the future at a

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time and at a price that we deem appropriate. These sales also could cause the trading price of our Common Stock to fall and make it more difficult for you to sell shares of our Common Stock at a time and price that you deem appropriate.

We have warrants outstanding that are exercisable for our Common Stock, which, if exercised, would increase the number of shares eligible for future resale in the public market and result in dilution to our shareholders.

Outstanding Public Warrants to purchase an aggregate of 8,333,287 shares of our Common Stock became exercisable on November 7, 2021 in accordance with the terms of the warrant agreement governing those securities, outstanding Private Placement Warrants to purchase an aggregate of 3,500,000 shares of our Common Stock became exercisable at Closing in accordance with the Sponsor Letter Agreement, and outstanding Private Placement Warrants to purchase an additional 583,334 shares of our Common Stock became exercisable on November 9, 2021, upon the occurrence of earnout milestone events pursuant to the Sponsor Letter Agreement and the Merger Agreement (the “Earnout Milestone Events”). The exercise price of each of these warrants is $11.50 per share.

To the extent such warrants are exercised, additional shares of our Common Stock will be issued, which will result in dilution to the holders of our Common Stock and increase the number of shares eligible for resale in the public market. Sales of substantial numbers of such shares in the public market or the fact that such warrants may be exercised could adversely affect the prevailing market prices of our Common Stock.

The Public Warrants may be amended in a manner adverse to a holder if holders of 65% of the then outstanding Public Warrants approve of such amendment.

Our warrants were issued in registered form under a warrant agreement between Continental Stock Transfer & Trust Company, as warrant agent, and STWO. The warrant agreement provides that the terms of the warrants may be amended without the consent of any holder to cure any ambiguity or correct any defective provision or correct any mistake, but requires the approval by the holders of 65% of the then-outstanding Public Warrants to make any change that adversely affects the interests of the registered holders of Public Warrants. Accordingly, we may amend the terms of the Public Warrants in a manner adverse to a holder if holders of 65% of the then-outstanding Public Warrants approve of such amendment and, solely with respect to any amendment to the terms of the Private Placement Warrants or any provision of the warrant agreement with respect to the Private Placement Warrants, 65% of the number of the then outstanding Private Placement Warrants. Although our ability to amend the terms of the Public Warrants with the consent of 65% of the then-outstanding Public Warrants is unlimited, examples of such amendments could be amendments to, among other things, increase the exercise price of the warrants, convert the warrants into cash, shorten the exercise period or decrease the number of shares of our Common Stock purchasable upon exercise of a warrant.

We may redeem your unexpired warrants prior to their exercise at a time that is disadvantageous to you, thereby making your warrants worthless.

We have the ability to redeem the outstanding Public Warrants at any time after they become exercisable and prior to their expiration, at a price of $0.01 per warrant, provided that the closing price of our Common Stock equals or exceeds $18.00 per share (as adjusted for share subdivisions, share dividends, rights issuances, subdivisions, reorganizations, recapitalizations and the like) for any 20 trading days within a 30 trading-day period ending on the third trading day prior to proper notice of such redemption and provided that certain other conditions are met. If and when the warrants become redeemable by us, we may exercise our redemption right even if we are unable to register or qualify the underlying securities for sale under all applicable state securities laws. As a result, we may redeem the warrants as set forth above even if the holders are otherwise unable to exercise the warrants. Redemption of the outstanding warrants could force you to (i) exercise your warrants and pay the exercise price therefor at a time when it may be disadvantageous for you to do so, (ii) sell your warrants at the then-current market price when you might otherwise wish to hold your warrants or (iii) accept the nominal redemption price which, at the time the outstanding warrants are called for redemption, we expect would be substantially less than the market value of your warrants.

In addition, we have the ability to redeem the outstanding Public Warrants at any time after they become exercisable and prior to their expiration, at a price of $0.10 per warrant upon a minimum of 30 days’ prior written notice of redemption provided that the closing price of the our Common Stock equals or exceeds $10.00 per share (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant) for any 20 trading days within a 30 trading-day period ending on the third trading day prior to proper notice of such redemption and provided that certain other conditions are met, including that holders will be able to exercise their warrants prior to redemption for a number of shares of Common Stock determined based on the redemption date and the fair market value of our Common Stock. The value received upon exercise of the warrants (1) may be less than the value the holders would have received if they had exercised their warrants at a later time where the underlying share price is higher and (2) may not compensate the holders for the value of the warrants, including because the number of ordinary shares received is capped at 0.361 shares of Common Stock per warrant (subject to adjustment) irrespective of the remaining life of the warrants.

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None of the Private Placement Warrants will be redeemable by us as so long as they are held by the Sponsor or its permitted transferees, except under certain circumstances.

We do not expect to declare any dividends in the foreseeable future.

We do not anticipate declaring any cash dividends to holders of the Common Stock in the foreseeable future. Consequently, investors may need to rely on sales of their shares after price appreciation, which may not occur for some time or not at all, as the only way to realize any future gains on their investment.

There can be no assurance that we will be able to comply with the continued listing standards of the NYSE.

Our Common Stock is listed on the NYSE under the symbol “GWH.” If the NYSE delists our securities from trading on its exchange for failure to meet the listing standards and we are not able to list such securities on another national securities exchange, we expect such securities could be quoted on an over-the-counter market. If this were to occur, we and our stockholders could face significant material adverse consequences including:

•a limited availability of market quotations for our securities;

•reduced liquidity for our securities;

•a limited amount of news and analyst coverage; and

•a decreased ability to issue additional securities or obtain additional financing in the future.

Reports published by analysts, including projections in those reports that differ from our actual results, could adversely affect the price and trading volume of our Common Stock.

Securities research analysts may establish and publish their own periodic projections for us. These projections may vary widely and may not accurately predict the results we actually achieve. Our share price may decline if our actual results do not match the projections of these securities research analysts. Similarly, if one or more of the analysts who write reports on us downgrades our stock or publishes inaccurate or unfavorable research about our business, our share price could decline. If one or more of these analysts ceases coverage of us or fails to publish reports on us regularly, our share price or trading volume could decline.

Provisions in our amended and restated certificate of incorporation and amended and restated bylaws and Delaware law might discourage, delay or prevent a change in control of our company or changes in our management and, therefore, depress the market price of our Common Stock.

Our amended and restated certificate of incorporation and amended and restated bylaws contain provisions that could delay or prevent a change of control of our company or changes in our board of directors that our stockholders might consider favorable. These provisions, among other things:

•establish a classified board of directors so that not all members of our board are elected at one time;

•permit only the board of directors to establish the number of directors and fill vacancies on the board;

•provide that directors may only be removed “for cause” and only with the approval of a majority of the voting power of the issued and outstanding capital stock of the Company entitled to vote in the election of directors;

•authorize the issuance of “blank check” preferred stock that our board could use to implement a stockholder rights plan (also known as a “poison pill”);

•eliminate the ability of our stockholders to call special meetings of stockholders;

•prohibit stockholder action by written consent, which requires all stockholder actions to be taken at a meeting of our stockholders;

•prohibit cumulative voting by stockholders at any election of directors;

•authorize our board of directors to amend the bylaws;

•establish advance notice requirements for nominations for election to our board or for proposing matters that can be acted upon by stockholders at annual stockholder meetings; and

•require a super-majority vote of stockholders to amend some provisions described above.

In addition, Section 203 of the DGCL, prohibits a publicly-held Delaware corporation from engaging in a business combination with an interested stockholder, generally a person which together with its affiliates owns, or within the last three years has owned, 15% of our voting stock, for a period of three years after the date of the transaction in which the person became an interested stockholder, unless the business combination is approved in a prescribed manner.

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Any provision of our amended and restated certificate of incorporation, amended and restated bylaws or Delaware law that has the effect of delaying or preventing a change in control could limit the opportunity for our stockholders to receive a premium for their shares of our capital stock and could also affect the price that some investors are willing to pay for our Common Stock.

Our amended and restated bylaws provide that the Court of Chancery of the State of Delaware and the federal district courts of the United States of America will be the exclusive forums for substantially all disputes between us and our stockholders, which could limit our stockholders’ ability to obtain a favorable judicial forum for disputes with us or our directors, officers or employees.

Our amended and restated bylaws provide that the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have jurisdiction, another State court in Delaware or the federal district court for the District of Delaware) is the exclusive forum for the following (except for any claim as to which such court determines that there is an indispensable party not subject to the jurisdiction of such court (and the indispensable party does not consent to the personal jurisdiction of such court within 10 days following such determination), which is vested in the exclusive jurisdiction of a court or forum other than such court or for which such court does not have subject matter jurisdiction):

•any derivative action or proceeding brought on our behalf;

•any action asserting a claim of breach of fiduciary duty owed by any director, stockholder, officer or other employee of the Company to the Company or to the Company’s stockholders;

•any action arising pursuant to any provision of the DGCL, our amended and restated certificate of incorporation or our amended and restated bylaws; and

•any action asserting a claim against us that is governed by the internal affairs doctrine.

This provision would not apply to suits brought to enforce a duty or liability created by the Securities Act, the Exchange Act or any other claim for which the U.S. federal courts have exclusive jurisdiction.

Our amended and restated bylaws further provide that, unless the Company consents in writing to the selection of an alternative forum, the federal district courts of the United States of America will be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act. We note that investors cannot waive compliance with the federal securities laws and the rules and regulations thereunder.

These exclusive forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers or other employees, which may discourage lawsuits against us and our directors, officers and other employees. Any person or entity purchasing or otherwise acquiring any interest in any of our securities shall be deemed to have notice of and consented to these provisions. There is uncertainty as to whether a court would enforce such provisions, and the enforceability of similar choice of forum provisions in other companies’ charter documents has been challenged in legal proceedings. While the Delaware courts have determined that such choice of forum provisions are facially valid, a stockholder may nevertheless seek to bring a claim in a venue other than those designated in the exclusive forum provisions, and there can be no assurance that such provisions will be enforced by a court in those other jurisdictions. If a court were to find these types of provisions to be inapplicable or unenforceable, and if a court were to find the exclusive forum provision in our amended and restated bylaws to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving the dispute in other jurisdictions, which could materially adversely affect our business.

Claims for indemnification by our directors and officers may reduce our available funds to satisfy successful third-party claims against us and may reduce the amount of money available to us.

Our amended and restated certificate of incorporation and amended and restated bylaws provide that we will indemnify our directors and officers, in each case to the fullest extent permitted by Delaware law.

In addition, as permitted by Section 145 of the DGCL, our amended and restated bylaws and our indemnification agreements that we have entered into with our directors and officers provide that:

•we indemnify our directors and officers for serving us in those capacities or for serving other business enterprises at our request, to the fullest extent permitted by Delaware law. Delaware law provides that a corporation may indemnify such person if such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the registrant and, with respect to any criminal proceeding, had no reasonable cause to believe such person’s conduct was unlawful;

•we may, in our discretion, indemnify employees and agents in those circumstances where indemnification is permitted by applicable law;

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•we are required to advance expenses, as incurred, to our directors and officers in connection with defending a proceeding, except that such directors or officers shall undertake to repay such advances if it is ultimately determined that such person is not entitled to indemnification;

•we are not obligated, pursuant to our amended and restated bylaws, to indemnify a person with respect to proceedings initiated by that person against us or our other indemnitees, except with respect to proceedings authorized by our board of directors or brought to enforce a right to indemnification;

•the rights conferred in our amended and restated bylaws are not exclusive, and we are authorized to enter into indemnification agreements with our directors, officers, employees and agents and to obtain insurance to indemnify such persons; and

•we may not retroactively amend our amended and restated bylaw provisions to reduce our indemnification obligations to directors; officers, employees and agents.

While we maintain a directors’ and officers’ insurance policy, such insurance may not be adequate to cover all liabilities that we may incur, which may reduce our available funds to satisfy third-party claims and may materially adversely affect our cash position.

ITEM 2. UNREGISTERED SALES OF EQUITY SECURITIES

None.

ITEM 3. DEFAULTS UPON SENIOR SECURITIES

None.

ITEM 4. MINE SAFETY DISCLOSURES

Not applicable.

ITEM 5. OTHER INFORMATION

None.

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ITEM 6. EXHIBITS

		Incorporated by Reference
Exhibit	Description	Form	File No.	Exhibit No.	Filing Date
2.1#	Merger Agreement, dated as of May 6, 2021, by and among STWO, SCharge Merger Sub, Inc. and ESS Tech, Inc.	8-K	001-39525	2.1	May 7, 2021
3.1	Amended and Restated Certification of Incorporation of ESS	8-K	001-39525	3.1	October 15, 2021
3.2	Amended and Restated Bylaws of ESS	8-K	001-39525	3.2	October 15, 2021
31.1*	Certification of Chief Executive Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
31.2*	Certification of Chief Financial Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
32.1**	Certification of Chief Executive Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2**	Certification of Chief Financial Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101.INS*	Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH*	Inline XBRL Taxonomy Extension Schema Document
101.CAL*	Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB*	Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE*	Inline XBRL Taxonomy Extension Presentation Linkbase Document
#	Portions of this exhibit have been omitted in accordance with Item 601 of Regulation S-K.
*	Filed herewith.
**	These exhibits are furnished with this Quarterly Report on Form 10-Q and are not deemed filed with the Securities and Exchange Commission and are not incorporated by reference in any filing of ESS Tech, Inc. under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, whether made before or after the date hereof and irrespective of any general incorporation language contained in such filings.

- 62 -

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Act of 1934, the registrant has duly caused this Quarterly Report on Form 10-Q to be signed on its behalf by the undersigned, thereunto duly authorized.

May 12, 2022
	ESS TECH, INC.
	By:	/s/ Eric P. Dresselhuys
		Name: Eric P. Dresselhuys
		Title: Chief Executive Officer

- 63 -

EX-31.1

EXHIBIT 31.1

CERTIFICATION

PURSUANT TO RULE 13a-14(a) AND 15d-14(a)

UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED,

AS ADOPTED PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Eric P. Dresselhuys, certify that:

1.I have reviewed this Quarterly Report on Form 10-Q for the quarter ended March 31, 2022 of ESS Tech, Inc.;

2.Based on my knowledge, this Report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this Report;

3.Based on my knowledge, the financial statements, and other financial information included in this Report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this Report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a.Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this Report is being prepared;

b.Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c.Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this Report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this Report based on such evaluation; and

d.Disclosed in this Report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a.All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b.Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal controls over financial reporting.

May 12, 2022	By:	/s/ Eric P. Dresselhuys
		Eric P. Dresselhuys
		Chief Executive Officer
		(Principal Executive Officer)

EX-31.2

EXHIBIT 31.2

CERTIFICATION

PURSUANT TO RULE 13a-14(a) AND 15d-14(a)

UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED,

AS ADOPTED PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Amir Moftakhar, certify that:

1.I have reviewed this Quarterly Report on Form 10-Q for the quarter ended March 31, 2022 of ESS Tech, Inc.;

2.Based on my knowledge, this Report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this Report;

3.Based on my knowledge, the financial statements, and other financial information included in this Report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this Report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a.Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this Report is being prepared;

b.Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c.Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this Report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this Report based on such evaluation; and

d.Disclosed in this Report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a.All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b.Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal controls over financial reporting.

May 12, 2022	By:	/s/ Amir Moftakhar
		Amir Moftakhar
		Chief Financial Officer
		(Principal Financial Officer)

EX-32.1

EXHIBIT 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Inconnection with the Quarterly Report of ESS Tech, Inc.(the“Company”)onForm10-Q forthe quarter endedMarch 31, 2022,asfiledwiththeSecuritiesandExchange Commissionon thedatehereof(the “Report”), I, Eric P. Dresselhuys, Chief Executive Officerof the Company, certify, pursuantto 18 U.S.C. Section1350, as adoptedpursuantto Section906 of theSarbanes-OxleyAct of 2002, that,to thebestof my knowledge:

1.the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2.theinformationcontainedintheReportfairlypresents,inallmaterialrespects,thefinancialconditionand resultsof operationsof the Company.

May 12, 2022	By:	/s/ Eric P. Dresselhuys
		Name: Eric P. Dresselhuys
		Title: Chief Executive Officer
		(Principal Executive Officer)

EX-32.2

EXHIBIT 32.2

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Inconnection with the Quarterly Report of ESS Tech, Inc.(the“Company”)onForm10-Q forthe quarter ended March 31, 2022,asfiledwiththeSecuritiesandExchange Commissionon thedatehereof(the “Report”), I,Amir Moftakhar,ChiefFinancialOfficerof the Company, certify, pursuantto 18 U.S.C. Section1350, as adoptedpursuantto Section906 of theSarbanes-OxleyAct of 2002, that,to thebestof my knowledge:

1.the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2.theinformationcontainedintheReportfairlypresents,inallmaterialrespects,thefinancialconditionand resultsof operationsof the Company.

May 12, 2022	By:	/s/ Amir Moftakhar
		Name: Amir Moftakhar
		Title: Chief Financial Officer
		(Principal Financial Officer)

XML

Cover - shares	3 Months Ended
	Mar. 31, 2022	May 09, 2022
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-39525
Entity Registrant Name	ESS Tech, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	98-1550150
Entity Address, Address Line One	26440 SW Parkway Ave.
Entity Address, Address Line Two	Bldg. 83
Entity Address, City or Town	Wilsonville
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97070
City Area Code	855
Local Phone Number	423-9920
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		152,654,728
Entity Central Index Key	0001819438
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	GWH
Security Exchange Name	NYSE
Common Stock Warrants
Entity Information [Line Items]
Title of 12(b) Security	Warrants, each whole warrant exercisable for one share of common stock at an exercise price of $11.50
Trading Symbol	GWH.W
Security Exchange Name	NYSE

XML

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 212,331	$ 238,940
Restricted cash, current	1,167	1,217
Accounts receivable, net	2,928	517
Prepaid expenses and other current assets	4,406	4,844
Total current assets	220,832	245,518
Property and equipment, net	10,056	4,501
Operating lease right-of-use assets	4,260	0
Restricted cash, non-current	75	75
Other non-current assets	261	105
Total assets	235,484	250,199
Current liabilities:
Accounts payable	1,745	1,572
Accrued and other current liabilities	6,615	6,487
Operating lease liabilities, current	1,310	0
Deferred revenue	6,859	3,663
Notes payable, current	1,817	1,900
Total current liabilities	18,346	13,622
Notes payable, non-current	1,483	1,869
Operating lease liabilities, non-current	3,612	0
Earnout warrant liabilities	636	1,476
Public warrant liabilities	8,042	18,666
Private warrant liabilities	3,815	8,855
Other non-current liabilities	101	552
Total liabilities	36,035	45,040
Commitments and contingencies (Note 10)
Stockholders’ equity:
Preferred stock ($0.0001 par value; 200,000,000 shares authorized, none issued and outstanding as of March 31, 2022 and December 31, 2021)	0	0
Common stock ($0.0001 par value; 2,000,000,000 shares authorized, 152,606,563 and 151,839,058 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively)	16	16
Additional paid-in capital	745,752	745,753
Accumulated deficit	(546,319)	(540,610)
Total stockholders' equity	199,449	205,159
Total liabilities and stockholders’ equity	$ 235,484	$ 250,199

XML

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	200,000,000	200,000,000
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, shares issued (in shares)	152,606,563	151,839,058
Common stock, shares outstanding (in shares)	152,606,563	151,839,058

XML

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 12,898	$ 5,652
Sales and marketing	1,501	512
General and administrative	7,789	2,120
Total operating expenses	22,188	8,284
Loss from operations	(22,188)	(8,284)
Other income (expenses), net:
Interest expense, net	(29)	(57)
Gain (loss) on revaluation of warrant liabilities	15,664	(8,426)
Loss on revaluation of derivative liabilities	0	(138,141)
Gain on revaluation of earnout liabilities	840	0
Other income (expense), net	4	(10)
Total other income (expenses), net	16,479	(146,634)
Net loss to common stockholders	$ (5,709)	$ (154,918)
Net loss per share, basic (in USD per share)	$ (0.04)	$ (2.51)
Net loss per share, diluted (in USD per share)	$ (0.04)	$ (2.51)
Weighted average shares used in per share calculation, basic (in shares)	151,683,819	61,693,067
Weighted average shares used in per share calculation, diluted (in shares)	151,683,819	61,693,067

XML

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Common Stock Warrants	Additional Paid-In Capital	Accumulated Deficit
Balance at beginning of period (in shares) at Dec. 31, 2020	0
Balance at beginning of period at Dec. 31, 2020	$ 0
Balance at end of period (in shares) at Mar. 31, 2021	0
Balance at end of period at Mar. 31, 2021	$ 0
Balance at beginning of period (in shares) at Dec. 31, 2020		58,919,345
Balance at beginning of period at Dec. 31, 2020	(27,888)	$ 6	$ 153	$ 35,446	$ (63,493)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Legacy ESS Redeemable Convertible Preferred Stock (in shares)		5,746,003
Issuance of Legacy ESS Redeemable Convertible Preferred Stock	29,516	$ 1		29,515
Issuance of common stock upon exercise of options (in shares)		2,379,260
Issuance of common stock upon exercise of options	518			518
Issuance of common stock upon exercise of warrants (in shares)		60,418
Issuance of common stock upon exercise of warrants	356			356
Stock-based compensation expense	129			129
Net loss	(154,918)
Balance at end of period (in shares) at Mar. 31, 2021		67,105,026
Balance at end of period at Mar. 31, 2021	$ (152,287)	$ 7	153	65,964	(218,411)
Balance at beginning of period (in shares) at Dec. 31, 2021	0
Balance at beginning of period at Dec. 31, 2021	$ 0
Balance at end of period (in shares) at Mar. 31, 2022	0
Balance at end of period at Mar. 31, 2022	$ 0
Balance at beginning of period (in shares) at Dec. 31, 2021		151,839,058
Balance at beginning of period at Dec. 31, 2021	$ 205,159	$ 16	0	745,753	(540,610)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)	138,617	138,617
Issuance of common stock upon exercise of options	$ 47			47
Issuance of common stock upon release of restricted stock units (in shares)		873,070
Cancellation of shares used to settle payroll tax withholding (in shares)		(244,202)
Cancellation of shares used to settle payroll tax withholding	(2,808)			(2,808)
Issuance of common stock upon exercise of warrants (in shares)		20
Stock-based compensation expense	2,760			2,760
Net loss	(5,709)				(5,709)
Balance at end of period (in shares) at Mar. 31, 2022		152,606,563
Balance at end of period at Mar. 31, 2022	$ 199,449	$ 16	$ 0	$ 745,752	$ (546,319)

XML

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (5,709)	$ (154,918)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	196	130
Non-cash interest expense	14	21
Non-cash lease expense	275	0
Stock-based compensation expense	2,760	129
Change in fair value of warrant liabilities	(15,664)	8,426
Loss on revaluation of derivative liabilities	0	138,141
Change in earnout liabilities	(840)	0
Changes in operating assets and liabilities:
Accounts receivable	785	0
Prepaid expenses and other assets	405	(294)
Prepaid expenses and other assets	(1,596)	1,882
Net cash used in operating activities	(19,374)	(6,483)
Cash flows from investing activities:
Purchases of property and equipment	(4,041)	(133)
Net cash used in investing activities	(4,041)	(133)
Cash flows from financing activities:
Principal payments on notes payable	(483)	(101)
Proceeds from stock options exercised	47	518
Repurchase of shares from employees for income tax withholding purposes	(2,808)	0
Proceeds from sale of Legacy ESS Series C-2 redeemable convertible preferred stock, net of issuance costs	0	11,461
Net cash (used in) provided by financing activities	(3,244)	11,878
Net change in cash, cash equivalents and restricted cash	(26,659)	5,262
Cash, cash equivalents and restricted cash, beginning of period	240,232	6,394
Cash, cash equivalents and restricted cash, end of period	213,573	11,656
Supplemental disclosures of cash flow information:
Cash paid for operating leases included in cash used in operating activities	403	0
Non-cash investing and financing transactions:
Purchase of property and equipment included in accounts payable and accrued and other current liabilities	2,235	22
Right-of-use operating lease assets obtained in exchange for lease obligations	4,534	0
Right-of-use finance lease assets obtained in exchange for lease obligations	123	0
Extinguishment of derivative liabilities upon sale of Legacy ESS Series C-2 redeemable convertible preferred stock, net of amount allocated to warrants	0	18,055
Extinguishment of warrant liabilities upon exercise of Legacy ESS Series B, Series C-1 and Series C-2 redeemable convertible preferred stock warrants	0	356
Cash and cash equivalents	212,331	10,163
Restricted cash, current	1,167	1,167
Restricted cash, non-current	75	326
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 213,573	$ 11,656

XML

DESCRITPION OF BUSINESS AND BASIS OF PRESENTATION

3 Months Ended

Mar. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

DESCRITPION OF BUSINESS AND BASIS OF PRESENTATION

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION

Description of Business—ESS Tech, Inc. (“ESS” or the “Company”) is a long-duration energy storage company specializing in iron flow battery technology. ESS develops long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring four or more hours of flexible energy capacity. The Company’s products are designed for a 25-year operating life without performance degradation, and with minimal annual operational and maintenance requirements. The Company is in the research and development phase. Its products are still being developed and do not yet meet standard specifications to be sold commercially (“Commercially Available”).

The Company was originally incorporated as a Cayman Islands exempted company on July 21, 2020 as a publicly traded special purpose acquisition company under the name ACON S2 Acquisition Corp. (“STWO”) for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination involving STWO and one or more businesses. On October 8, 2021 (the “Closing Date”), the Company consummated the merger agreement (the “Merger Agreement”) dated May 6, 2021, by and among STWO, SCharge Merger Sub, Inc., a Delaware corporation and wholly owned direct subsidiary of STWO (“Merger Sub”), and ESS Tech, Inc., a Delaware corporation (“Legacy ESS”) following the approval at a special meeting of the stockholders of STWO held on October 5, 2021.

Pursuant to the terms of the Merger Agreement, STWO deregistered by way of continuation under the Cayman Islands Companies Act (2021 Revision) and registered as a corporation in the State of Delaware under Part XII of the Delaware General Corporation Law (the “Domestication”), and a business combination between STWO and Legacy ESS was effected through the merger of Merger Sub with and into Legacy ESS, with Legacy ESS surviving as a wholly owned subsidiary of STWO (together with the other transactions described in the Merger Agreement, the “Business Combination”). On the Closing Date, STWO changed its name from “ACON S2 Acquisition Corp” to “ESS Tech, Inc.”, and its common shares of stock and warrants for shares of ESS common stock commenced trading on the New York Stock Exchange under the new ticker symbols “GWH” and “GWH.W”, respectively.

Basis of Presentation—The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Pursuant to the Merger Agreement, the merger between Merger Sub and Legacy ESS was accounted for as a reverse recapitalization in accordance with U.S. GAAP (the “Reverse Recapitalization”). Under this method of accounting, STWO was treated as the “acquired” company and Legacy ESS was treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Reverse Recapitalization was treated as the equivalent of Legacy ESS issuing stock for the net assets of STWO, accompanied by a recapitalization. The net assets of STWO were stated at historical cost, with no goodwill or other intangible assets recorded. Legacy ESS was determined to be the accounting acquirer based on the following predominant factors:

•Legacy ESS’s existing stockholders had the greatest voting interest in the Company;

•Legacy ESS’s directors represented all of the new board of directors of the Company;

•Legacy ESS’s senior management continued as the senior management of the Company; and,

•Legacy ESS had the larger employee base.

The assets, liabilities and results of operations prior to the Reverse Recapitalization are those of Legacy ESS. The shares and corresponding capital amounts and losses per share, prior to the Reverse Recapitalization, have been retroactively restated based on shares reflecting the exchange ratio of approximately 1.47 (the “Per Share Consideration”) established in the Business Combination.

Unaudited Interim Financial Statements—The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. GAAP for interim financial information and in accordance with the rules and regulations of the SEC. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The unaudited consolidated financial statements reflect all normal and recurring adjustments that are, in the opinion of the Company’s management, necessary in order to make the consolidated financial statements not misleading. Operating results for the three months ended March 31, 2022 are not necessarily indicative of the results that may be expected for the year ending December 31, 2022. These unaudited interim consolidated financial statements should be read in conjunction with the consolidated financial statements and related

notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021, as filed with the SEC on March 4, 2022.

Reclassifications—Certain prior year amounts have been reclassified to conform with current year presentation.

XML

SIGNIFICANT ACCOUNTING POLICIES

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates—The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Such estimates relate to, among others, the useful lives and assessment of recoverability of property and equipment, deferred tax assets valuation, determination of the fair value of the Company’s earnout warrant liabilities and private warrants, as well as other accruals. These estimates are based on historical trends, market pricing, current events and other relevant assumptions and data points. Actual results could differ from those estimates and such differences may be material to the consolidated financial statements.

Net Loss Per Share—The Company follows the two-class method when computing net income (loss) per common share when shares are issued that meet the definition of participating securities. Under this method, net earnings are reduced by the amount of dividends declared in the current period for common shareholders and participating security holders. The remaining earnings or “undistributed earnings” are allocated between common stock and participating securities to the extent that each security may share in earnings as if all the earnings for the period had been distributed. Once calculated, the earnings per common share is computed by dividing the net income (loss) attributable to common shareholders by the weighted average number of common shares outstanding during each year presented. Diluted income (loss) attributable to common shareholders per common share has been computed by dividing the net income (loss) attributable to common shareholders by the weighted average number of common shares outstanding plus the dilutive effect of outstanding options, warrants, and restricted stock units (“RSU”) during the respective periods computed using the treasury method. In cases where the Company has a net loss, no dilutive effect is shown as options, warrants, RSU, and earnout shares pending satisfaction of a regulatory holding period become anti-dilutive.

Cash and Cash Equivalents—The Company considers all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents. Cash equivalents are recorded at carrying value, which approximates fair value. Cash and cash equivalents include cash in bank accounts and money market funds.

Restricted Cash—Restricted cash is required as collateral for certain of the Company’s lease agreements and contractual supply and service arrangements. Restricted cash includes a certificate of deposit for the Company’s lease agreements and a performance and payment bond for the Company’s supply and service arrangements. The certificate of deposit and bond are recorded at carrying value, which approximates fair value. Restricted cash amounts are reported in the consolidated balance sheets as current or non-current depending on when the cash will be contractually released.

Revenue Recognition—The Company did not recognize any revenue in either of the three month periods ended March 31, 2022 or 2021. The Company will recognize revenue in accordance with the requirements of, and the guidance provided by Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers (Topic 606).

Stock-Based Compensation—The Company accounts for stock-based compensation in accordance with ASC 718, Compensation – Stock Compensation. The Company measures and recognizes compensation expense for all stock-based awards based on estimated fair values on the date of the grant, recognized over the requisite service period. For awards that vest solely based on a service condition, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period. The compensation expense related to awards with performance conditions is recognized over the requisite service period when the performance conditions are probable of being achieved. The compensation expense related to awards with market conditions is recognized on an accelerated attribution basis over the requisite service period identified as the derived service period over which the market conditions are expected to be achieved, and is not reversed if the market condition is not satisfied. The Company accounts for forfeitures as they occur. Stock-based awards granted to employees are primarily stock options and RSUs.

The fair value of each stock option granted is estimated using the Black-Scholes Merton option-pricing model using the single-option award approach. The following assumptions are used in the Black-Scholes Merton option-pricing model:

Risk-Free Interest Rate—The risk-free interest rate is based on the implied yield available on the date of grant on U.S. Treasury zero-coupon issued with a term that is equal to the option’s expected term at the grant date.

Expected Volatility—The Company estimates the volatility for option grants by evaluating the average historical volatility of a peer group of companies for the period immediately preceding the option grant for a term that is approximately equal to the option’s expected term.

Expected Term—The expected term for employees represents the period over which options granted are expected to be outstanding using the simplified method, as the Company’s historical share option exercise experience does not provide a reasonable basis upon which to estimate the expected term. The simplified method deems the term to be the average of the time-to-vesting and contractual life of the stock-based awards.

Dividend Yield—The Company has not declared or paid dividends to date and does not anticipate declaring dividends. As such, the dividend yield has been estimated to be zero.

Fair Value—The Company follows ASC 820, Fair Value Measurements (“ASC 820”), which establishes a common definition of fair value to be applied when U.S. GAAP requires the use of fair value, establishes a framework for measuring fair value, and requires certain disclosure about such fair value measurements.

ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about what market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs as follows:

Level 1: Observable inputs such as quoted prices in active markets for identical assets or liabilities to which the Company has access at a measurement date.

Level 2: Observable inputs other than Level 1 quoted prices that are observable for the asset or liability, either directly or indirectly; these include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3: Unobservable inputs for which little or no market data exists and for which the Company must develop its own assumptions regarding the assumptions that market participants would use in pricing the asset or liability, including assumptions regarding risk.

Because of the uncertainties inherent in the valuation of assets or liabilities for which there are no observable inputs, those estimated fair values may differ significantly from the values that may have been used had a ready market for the assets or liabilities existed.

Recent Accounting Pronouncements—Pursuant to the Jumpstart Our Business Startups Act (“JOBS Act”), an emerging growth company is provided the option to adopt new or revised accounting standards that may be issued by the FASB or the SEC either (i) within the same periods as those otherwise applicable to non-emerging growth companies or (ii) within the same time periods as private companies. The Company has elected to use the extended transition period for complying with any new or revised financial accounting standards. As a result, the Company’s consolidated financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective date for new or revised accounting standards that are applicable to public companies. The Company also intends to continue to take advantage of some of the reduced regulatory and reporting requirements of emerging growth companies pursuant to the JOBS Act so long as the Company qualifies as an emerging growth company.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with a forward-looking expected credit loss model, which will result in earlier recognition of credit losses. ASU 2016-13 is effective for emerging growth companies for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The Company is currently evaluating the impact that the standard will have on its consolidated financial statements and related disclosures.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes. ASU 2019-12 is effective for emerging growth companies for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. The Company is currently evaluating the impact that the standard will have on its consolidated financial statements and related disclosures.

Recently Adopted Accounting Pronouncements—On January 1, 2022, the Company adopted ASU 2016-02, Leases (ASC 842), which superseded previous guidance related to accounting for leases within Topic 840, Leases. The Company elected the practical expedient provided under ASU 2018-11, Leases (Topic 842) Targeted Improvements, which amended ASU 2016-02 to provide entities an optional transition practical expedient to adopt the new standard with a cumulative effect adjustment as of the beginning of the year of adoption with prior year comparative financial information and disclosures remaining as previously reported. As a result, no adjustments were made to the consolidated balance sheet prior to January 1, 2022 and amounts are reported in accordance with historical accounting under Topic 840, while the consolidated balance sheet as of March 31, 2022 is presented under Topic 842.

The Company elected the package of practical expedients permitted under the transition guidance, which allowed it to carry forward historical lease classification, assessment on whether a contract was or contains a lease, and assessment of initial direct costs for any leases that existed prior to January 1, 2022. The Company also elected to combine its lease and non-lease components and to keep leases with an initial term of 12 months or less off the consolidated balance sheet and recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term.

For new required disclosures and further information see Note 8, Leases. Adoption of the new standard resulted in the recording of lease assets and lease liabilities of $4,534 thousand and $5,229 thousand, respectively, as of January 1, 2022. The transition did not have a material impact on the Company’s results of operations, cash flows or liquidity measures.

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BUSINESS COMBINATION

3 Months Ended

Mar. 31, 2022

Business Combination and Asset Acquisition [Abstract]

BUSINESS COMBINATION

BUSINESS COMBINATION

As discussed in Note 1, on October 8, 2021, the Company consummated the Business Combination pursuant to the Merger Agreement, with Legacy ESS surviving the Business Combination as a wholly owned subsidiary of the Company. Upon the Business Combination closing (the “Closing”), each share of Legacy ESS’s common stock, par value $0.0001 per share (“Legacy ESS Common Stock”) and Preferred Stock, par value $0.0001 per share (“Legacy ESS Preferred Stock”), were converted into the right to receive shares of the Company’s common stock at the Per Share Consideration as calculated pursuant to the Merger Agreement. The aggregate consideration paid to Legacy ESS stockholders in connection with the Business Combination (excluding any potential Earnout Shares (see below for definition)), was 99,700,326 shares of the Company’s common stock (including 125,958 shares of common stock issued following the Closing as a result of a transaction expense adjustment as disclosed in the Company’s Form 8-K filed with the SEC on November 15, 2021).

Pursuant to the Merger Agreement, the Company was permitted to issue to eligible Legacy ESS securityholders, on a pro rata basis, up to 16,500,000 shares of additional common stock (the “Earnout Shares”) less any RSUs issued pursuant to the Incentive RSU Pool, issuable in two equal tranches upon the occurrence of the respective Earnout Milestone Events. The Earnout Milestone Events were achieved on November 9, 2021 and Legacy ESS issued 15,674,965 shares to securityholders.

Upon the closing of the Business Combination, the Company's certificate of incorporation was amended and restated to, among other things, increase the total number of authorized shares of capital stock to 2,200,000,000, of which 2,000,000,000 shares are Common Stock, $0.0001 par value per share, and 200,000,000 shares are Preferred Stock, $0.0001 value per share.

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NET LOSS PER SHARE

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

NET LOSS PER SHARE

LOSS PER SHARE

The following table presents the calculation of basic and diluted net loss per share attributable to common stockholders (in thousands, except per share data):

	Three Months Ended March 31,
	2022		2021
Net loss attributable to common stockholders	$	(5,709)	$	(154,918)
Weighted-average shares outstanding – Basic and Diluted	151,683,819		61,693,067
Net loss per share – Basic and Diluted	$	(0.04)	$	(2.51)

Due to the net losses for the three months ended March 31, 2022 and 2021, basic and diluted net loss per common share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

The following outstanding balances of common share equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented:

	March 31, 2022	March 31, 2021
Stock options	3,707,113	4,379,633
RSUs	4,633,968	—
Warrants	11,461,227	3,362,047
Number of securities outstanding	19,802,308	7,741,680

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PREPAID EXPENSES AND OTHER CURRENT ASSETS

3 Months Ended

Mar. 31, 2022

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

PREPAID EXPENSES AND OTHER CURRENT ASSETS

PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Insurance	$	2,397	$	3,482
Vendor advances	1,514		1,103
Other	495		259
Total prepaid expenses and other current assets	$	4,406	$	4,844

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PROPERTY AND EQUIPMENT, NET

3 Months Ended

Mar. 31, 2022

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT, NET

PROPERTY AND EQUIPMENT, NET

Property and equipment, net consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Machinery and equipment	$	2,910	$	2,868
Furniture and fixtures	88		90
Leasehold improvements	1,030		746
Construction in process	7,944		2,517
Total property and equipment	11,972		6,221
Less accumulated depreciation	(1,916)		(1,720)
Total property and equipment, net	$	10,056	$	4,501

Depreciation and amortization expense related to property and equipment, net was $196 thousand and $130 thousand for the three months ended March 31, 2022 and 2021, respectively.

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ACCRUED AND OTHER CURRENT LIABILITIES

3 Months Ended

Mar. 31, 2022

Payables and Accruals [Abstract]

ACCRUED AND OTHER CURRENT LIABILITIES

ACCRUED AND OTHER CURRENT LIABILITIES

Accrued and other current liabilities consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Payroll and related benefits	$	1,552	$	1,876
Materials and related purchases	2,596		2,108
Deferred rent	—		142
Professional and consulting fees	1,140		1,820
Other	1,327		541
Total accrued and other current liabilities	$	6,615	$	6,487

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LEASES

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

LEASES

LEASES

The Company determines if an arrangement is a lease at inception and whether the arrangement is classified as an operating or finance lease. At commencement of the lease, the Company records a right-of-use (“ROU”) asset and lease liability in the consolidated balance sheets based on the present value of lease payments over the term of the arrangement. ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. As the Company’s leases do not provide an implicit rate, it uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The Company determines its incremental borrowing rate based on publicly available data for instruments with similar characteristics, including recently issued debt, as well as other factors. Contract terms may include options to extend or terminate the lease, and when the Company deems it reasonably certain that ESS will exercise that option it is included in the ROU asset and lease liability. Operating leases will reflect lease expense on a straight-line basis, while finance leases will result in the separate presentation of interest expense on the lease liability and amortization expense of the ROU asset.

ROU assets related to the Company’s operating leases are included in operating lease ROU assets, while the corresponding lease liabilities are included in current and non-current operating lease liabilities on our consolidated balance sheets. ROU assets related to the Company’s finance leases are included in other non-current assets, while the corresponding lease liabilities are included in accrued and other current liabilities and other non-current liabilities on the Company’s consolidated balance sheets.

The Company does not record leases with a term of 12-months or less in the consolidated balance sheets. There was no short-term lease cost for the three months ended March 31, 2022.

The Company leases office and manufacturing space in Wilsonville, Oregon under operating leases and printers and copiers under finance leases. Each of the operating leases provides the Company an option to renew the lease for an additional 60 months which have not been included in the operating lease obligations.

Operating lease costs for the three months ended March 31, 2022 were $371 thousand. As of March 31, 2022, the weighted-average remaining term for the operating leases was 3.4 years and the weighted-average discount rate was 7.5%. The weighted-average remaining term for the finance lease was 4.9 years and the weighted-average discount rate was 7.5%.

As of March 31, 2022 future maturities of lease liabilities are as follows (in thousands):

	Operating Leases		Finance Leases
2022	$	1,222	$	21
2023	1,670		30
2024	1,720		30
2025	983		30
2026	—		30
Thereafter	—		7
Total minimum lease payments	$	5,595	$	148
Less imputed interest	(673)		(25)
Total	$	4,922	$	123

LEASES

LEASES

The Company determines if an arrangement is a lease at inception and whether the arrangement is classified as an operating or finance lease. At commencement of the lease, the Company records a right-of-use (“ROU”) asset and lease liability in the consolidated balance sheets based on the present value of lease payments over the term of the arrangement. ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. As the Company’s leases do not provide an implicit rate, it uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The Company determines its incremental borrowing rate based on publicly available data for instruments with similar characteristics, including recently issued debt, as well as other factors. Contract terms may include options to extend or terminate the lease, and when the Company deems it reasonably certain that ESS will exercise that option it is included in the ROU asset and lease liability. Operating leases will reflect lease expense on a straight-line basis, while finance leases will result in the separate presentation of interest expense on the lease liability and amortization expense of the ROU asset.

ROU assets related to the Company’s operating leases are included in operating lease ROU assets, while the corresponding lease liabilities are included in current and non-current operating lease liabilities on our consolidated balance sheets. ROU assets related to the Company’s finance leases are included in other non-current assets, while the corresponding lease liabilities are included in accrued and other current liabilities and other non-current liabilities on the Company’s consolidated balance sheets.

The Company does not record leases with a term of 12-months or less in the consolidated balance sheets. There was no short-term lease cost for the three months ended March 31, 2022.

The Company leases office and manufacturing space in Wilsonville, Oregon under operating leases and printers and copiers under finance leases. Each of the operating leases provides the Company an option to renew the lease for an additional 60 months which have not been included in the operating lease obligations.

Operating lease costs for the three months ended March 31, 2022 were $371 thousand. As of March 31, 2022, the weighted-average remaining term for the operating leases was 3.4 years and the weighted-average discount rate was 7.5%. The weighted-average remaining term for the finance lease was 4.9 years and the weighted-average discount rate was 7.5%.

As of March 31, 2022 future maturities of lease liabilities are as follows (in thousands):

	Operating Leases		Finance Leases
2022	$	1,222	$	21
2023	1,670		30
2024	1,720		30
2025	983		30
2026	—		30
Thereafter	—		7
Total minimum lease payments	$	5,595	$	148
Less imputed interest	(673)		(25)
Total	$	4,922	$	123

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BORROWINGS

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

BORROWINGS

BORROWINGS

Long term debt consists of the following (in thousands):

	March 31, 2022		December 31, 2021
Total notes payable	$	3,300	$	3,769
Less current portion of notes payable	1,817		1,900
Notes payable, non-current	$	1,483	$	1,869

Notes Payable

In 2018, the Company entered into a $1,000 thousand note payable with a bank that was secured by all property of the Company, except for its intellectual property. The note payable’s original maturity date was July 1, 2021.

In March 2020, the Company amended the note payable and borrowed an additional $4,000 thousand. The additional $4,000 thousand borrowing changed the present value of cash flows by more than 10% and, as such, was treated as a debt extinguishment. The Company recognized a $62 thousand loss on extinguishment of debt for the year ended December 31, 2021. The Company’s notes payable to the bank were recorded at fair value as part of the extinguishment. The $4,000 thousand note payable’s original maturity date was January 1, 2023.

In April 2020, the Company entered into a deferral agreement (“Deferral Agreement”) to extend the maturity date of the original $1,000 thousand note payable to September 1, 2022 and extend the maturity date of the additional $4,000 thousand note payable to January 1, 2024. The Company accounted for the Deferral Agreement as a debt modification based on an analysis of cash flows before and after the debt modification.

The notes payable bear interest at 0.50% below the bank’s prime rate (3.00% on March 31, 2022). The Company makes monthly interest and principal payments on the note payable based on the schedule defined in the agreement.

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COMMITMENTS AND CONTINGENCIES

3 Months Ended

Mar. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES

The Company, from time to time, is a party to various claims, legal actions, and complaints arising in the ordinary course of business. The Company is not aware of any legal proceedings or other claims, legal actions, or complaints through the date of issuance of these consolidated financial statements.

As of March 31, 2022, and December 31, 2021, the Company had a standby letter of credit with First Republic Bank totaling $725 thousand as security for an operating lease of office and manufacturing space in Wilsonville, Oregon. As of March 31, 2022 the letter of credit was secured by a restricted certificate of deposit account totaling $75 thousand. There were no draws against the letter of credit during the three months ended March 31, 2022 and 2021.

The Company purchases materials from several suppliers and has entered into agreements with various contract manufacturers, which include cancellable and noncancellable purchase commitments.

As of March 31, 2022 and December 31, 2021, total unfulfilled noncancellable purchase commitments were $23,344 thousand and $10,160 thousand, respectively. In addition, total unfulfilled cancellable purchase commitments amounted to $3,539 thousand and $10,446 thousand as of March 31, 2022, and December 31, 2021, respectively. These purchase commitments were not recorded in the consolidated financial statements.

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LEGACY ESS REDEEMABLE CONVERTIBLE PREFERRED STOCK

3 Months Ended

Mar. 31, 2022

Temporary Equity Disclosure [Abstract]

LEGACY ESS REDEEMABLE CONVERTIBLE PREFERRED STOCK

LEGACY ESS REDEEMABLE CONVERTIBLE PREFERRED STOCK

All Legacy ESS redeemable convertible preferred stock classified as redeemable was converted into Legacy ESS common stock, which was subsequently exchanged for the Company’s common stock as a result of the Business Combination using the Per Share Consideration of approximately 1.47. All preferred stock amounts have been retroactively adjusted to reflect the Business Combination.

Immediately prior to the completion of the Business Combination on October 8, 2021, all outstanding shares of Legacy ESS’s redeemable convertible preferred stock converted into an aggregate 57,104,332 shares of common stock.

Legacy ESS Rights to Purchase Series C-2 Convertible Preferred Stock

Legacy ESS’s Series C redeemable convertible preferred stock financing agreement initially provided additional committed funding of up to $79,999 thousand, through the purchase of up to 39,971,716 shares of Series C-2 redeemable convertible preferred stock based on the completion of certain operational milestones at a predetermined price of $2.00 per share, to certain Series C-1 Investors.

Legacy ESS determined that its obligation to issue, and Legacy ESS’s investors’ obligation to purchase shares of Series C-2 redeemable convertible preferred stock at a fixed price represents a freestanding derivative financial instrument (the “Series C-2 Redeemable Convertible Preferred Stock Issuance Right”). The Series C-2 Redeemable Convertible Preferred Stock Issuance Right was initially recorded at fair value and was adjusted to fair value at each reporting date, with the change in fair value recorded as a revaluation of derivative liabilities as a component of other income and expense in the consolidated statement of operations. The Series C-2 Redeemable Convertible Preferred Stock Issuance Right was initially scheduled to expire in August 2021 and was classified as a non-current derivative liability as of March 31, 2021.

The Series C-2 Redeemable Convertible Preferred Stock Issuance Right was initially valued at a fair value of $11,379 thousand.

Sale of Legacy ESS Series C-2 Redeemable Convertible Preferred Stock

In March 2021, Legacy ESS issued 5,746,003 shares of Series C-2 redeemable convertible preferred stock for $2.00 per share, totaling $11,500 thousand. Legacy ESS incurred $39 thousand in costs associated with the issuance. In connection with the sale of the Series C-2 redeemable convertible preferred stock, Legacy ESS issued warrants to purchase 861,896 shares of Series C-2 redeemable convertible preferred stock and extinguished a portion of the C-2 Purchase Right for 5,746,003 shares. The warrants were exercisable at a price of $0.0001 per share. The extinguishment of a portion of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right reduced Legacy ESS’s derivative liabilities and increased the amount attributable to the issuance by $23,152 thousand. Total transaction value of $34,613 thousand was allocated to the Series C-2 redeemable convertible preferred stock and warrants in the amounts of $29,516 thousand and $5,096 thousand, respectively.

Amendment to Legacy ESS Series C-2 Redeemable Convertible Preferred Stock Purchase Right and Related Warrants

On May 7, 2021, Legacy ESS amended its Series C-2 Preferred Stock Purchase Agreement and Amendment to Series C Preferred Stock Purchase Agreement. Under the terms of the amended agreement, the number of shares of C-2 Convertible Redeemable Preferred Stock required to be issued by Legacy ESS and purchased by investors under the C-2 Redeemable Convertible Preferred Stock Purchase Right were adjusted, and Legacy ESS issued Series C-2 warrants. The Series C-2 warrants were exercisable at a price of $.00007 per share upon a successful Business Combination with STWO. The investors were permitted to purchase shares subject to the C-2 Redeemable Convertible Preferred Stock Purchase Right at any time and must purchase the shares upon the Company’s achievement of specific milestones. The number of shares subject to and potential proceeds from the C-2 Redeemable Convertible Preferred Stock Purchase Agreement and related C-2 Warrants were as follows:

	As of May 7, 2021
	Upon completion of the Business Combination
	Quantity	Price
Series C-2 Redeemable Convertible Preferred Stock Purchase Right	7,994,442	$	2.00
Series C-2 Warrant exercisable upon completion of the Business Combination	21,159,364	$	0.00007

The C-2 warrants and Purchase Rights were exercised in conjunction with the Business Combination which closed on October 8, 2021 and the Company received proceeds of $15,559 thousand, which were net of $439 thousand in issuance costs.

The Company recorded a net increase in the derivative liability of $138,141 thousand for the three months ended March 31, 2021 for changes in the estimated fair value of the Series C-2 Redeemable Convertible Preferred Stock Purchase Right and C-2 Warrant exercisable upon completion of the Business Combination.

Legacy ESS Warrants

Legacy ESS Series B redeemable convertible preferred stock warrants were issued at exercise prices ranging from $0.0007 per share to $0.83 per share. 100,161 shares of Series B redeemable convertible preferred stock warrants had a 10-year exercise period and the remainder did not expire until a significant transaction had occurred, as defined by the warrant purchase agreement. The warrants were fully vested at the issuance date.

Legacy ESS Series C-1 and C-2 redeemable convertible preferred stock warrants were issued with prices ranging from $0.00007 to $1.25 per share, a life of 10 years and were fully vested at issuance.

Legacy ESS common stock warrants, all issued at a price of $0.0007 per share, were recorded at fair value within equity. Legacy ESS common stock warrants were fully vested at issuance and did not expire until a significant transaction has occurred, as defined by the Warrant Purchase Agreement.

In connection with the Business Combination, all Legacy ESS warrants were exercised during the year ended December 31, 2021.

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COMMON STOCK WARRANTS

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

COMMON STOCK WARRANTS

COMMON STOCK WARRANTSAs of March 31, 2022, the Company had 7,377,893 warrants to purchase common stock listed on the New York Stock Exchange (“NYSE”) under the ticker symbol “GWH.W” (the “Public Warrants”), 3,500,000 warrants to purchase

common stock issued in a private placement concurrently with STWO’s initial public offering (the “Private Warrants”) and 583,334 Earnout Warrants (as defined below) outstanding.

As part of STWO’s initial public offering, 8,333,287 Public Warrants were sold. The Public Warrants entitle the holder thereof to purchase one share of common stock at a price of $11.50 per share, subject to adjustments. The Public Warrants may be exercised only for a whole number of shares of common stock. No fractional shares will be issued upon exercise of the warrants. The Public Warrants will expire five years after completion of the business combination, on October 8, 2026, or earlier upon redemption or liquidation.

The Company may call the Public Warrants for redemption starting anytime, in whole and not in part, at a price of $0.01 per warrant, so long as the Company provides not less than 30 days prior written notice of redemption to each warrant holder, and if, and only if, the reported last sale price of common stock equals or exceeds $18.00 per share or $10.00 per share for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date the Company sends the notice of redemption to the warrant holders provided there is an effective registration statement covering the shares of common stock issuable upon exercise of the warrants.

The Company may call the Public Warrants for redemption starting anytime, in whole and not in part, at a price of $0.10 per warrant, so long as the Company provides not less than 30 days prior written notice of redemption to each warrant holder; provided that holders will be able to exercise their warrants on a cashless basis prior to redemption and receive a number of shares determined based on the redemption date fair market value of the shares, and if, and only if, the reported last sale price of common stock equals or exceeds $10.00 per share or $10.00 per share for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date the Company sends the notice of redemption to the warrant holders provided there is an effective registration statement covering the shares of common stock issuable upon exercise of the warrants.

Simultaneously with STWO’s initial public offering, STWO consummated a private placement of 4,666,667 Private Warrants with STWO’s sponsor. In connection with the Business Combination, STWO’s sponsor agreed to forfeit 583,333 Private Warrants. Of the remaining 4,083,334 Private Warrants, 3,500,000 were immediately vested and 583,334 warrants (the “Earnout Warrants”) were vested upon meeting certain Earnout Milestone Events on November 9, 2021. Each Private Warrant and Earnout Warrant is exercisable for one share of common stock at a price of $11.50 per share, subject to adjustment.

The Private Warrants and Earnout Warrants, post vesting on November 9, 2021, are identical to the Public Warrants, except that the Private Warrants and Earnout Warrants and the shares of common stock issuable upon exercise of the Private Warrants are not transferable, assignable or salable until 30 days after the completion of a Business Combination, subject to certain limited exceptions. Additionally, the Private Warrants and Earnout Warrants are non-redeemable so long as they are held by the initial purchasers or such purchasers’ permitted transferees. If the Private Warrants and Earnout Warrants are held by someone other than their initial purchasers or their permitted transferees, then the Private Warrants and Earnout Warrants will be redeemable by the Company and exercisable by such holders on the same basis as the Public Warrants. Additionally, if the Company redeems the Public Warrants when the common stock equals or exceeds $10.00 per share for any 20 trading days within a 30-day period ending on the third trading day prior to the date the Company sends the notice of redemption to warrant holders and the closing price of the common share for any 20 trading days within the same period is less than $18.00 per share, the Company must concurrently redeem the Private Warrants and Earnout Warrants.

The table below shows the common stock warrant activities during the three months ended March 31, 2022:

	December 31, 2021	Issued	Exercised	March 31, 2022
Earnout Warrants	583,334	—	—	583,334
Public Warrants	7,377,913	—	20	7,377,893
Private Warrants	3,500,000	—	—	3,500,000
Total Common Stock Warrants	11,461,247	—	20	11,461,227

The Company’s common stock warrants were initially recorded at fair value upon completion of the Business Combination and are adjusted to fair value at each reporting date based on the market price of the Public Warrants, with the change in fair value recorded as a component of other income and expense in the consolidated statements of operations. For the three months ending March 31, 2022, the Company recorded a net decrease to the liabilities for Earnout Warrants, Public Warrants and Private Warrants of $840 thousand, $10,624 thousand and $5,040 thousand, respectively.

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STOCK-BASED COMPENSATION PLAN

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION PLAN

STOCK-BASED COMPENSATION PLAN

2021 Equity Incentive Plan

In October 2021, the Board of Directors of the Company adopted the ESS Tech Inc. 2021 Equity Incentive Plan (the “2021 Plan”). The 2021 Plan became effective upon consummation of the Business Combination. The stock awards may be issued as Incentive Stock Options (“ISO”), Non-statutory Stock Options (“NSO”), Stock Appreciation Rights, Restricted Stock Awards, or Restricted Stock Unit Awards. Only employees are eligible to receive ISO awards. Employees, directors, and consultants who are providing continuous service to the Company are eligible to receive stock awards other than ISOs. The number of Shares available for issuance under the 2021 Plan will be increased on the first day of each fiscal year beginning with the 2022 fiscal year and ending with the 2031 Fiscal Year, in an amount equal to the lesser of (i) 15,260,000 Shares, (ii) five percent (5%) of the outstanding shares on the last day of the immediately preceding fiscal year, or (iii) such number of shares determined by the Company no later than the last day of the immediately preceding fiscal year. Under the 2021 Plan, the Company is authorized to issue 17,610,000 shares of common stock as of March 31, 2022.

Option prices for incentive stock options are set at the fair market value of the Company’s common stock at the date of grant. Employee new hire options generally cliff vest at the end of the first year and then 1/48th of the original grant over the remaining three years. Grants expire 10 years from the date of grant.

No ISOs, NSOs, Restricted Stock Awards, nor Stock Appreciation Rights were outstanding as of March 31, 2022.

Shares Available for Future Grant

As of March 31, 2022, there were 13,021,489 shares available for future grant under the 2021 Plan.

Stock option and RSU activity, prices, and values during the three months ended March 31, 2022 is as follows (in thousands, except for share, per share, and contractual term data):

	Options Outstanding						RSUs
	Number of shares	Weighted average exercise price		Weighted average remaining  contractual term (years)	Aggregate intrinsic values ($'000s)		Number of plan shares outstanding	Weighted average grant date fair value per Share
Balances as of December 31, 2021	3,796,530	$	0.83	8.08	$	40,274	3,392,153	$	10.69
Options and RSUs granted	65,717	8.00					2,150,859	5.46
Options exercised and RSUs released	(138,617)	0.30					(873,070)	11.12
Options and RSUs forfeited	(16,517)	0.36					(35,974)	10.15
Balances as of March 31, 2022	3,707,113	$	0.98	8.03	$	17,012	4,633,968	$	8.82
Options vested and exercisable - December 31, 2021	1,827,374	$	0.31	7.20	$	20,337
Options vested and exercisable - March 31, 2022	1,626,013	$	0.56	7.41	$	8,140

In accordance with ASC 718, Compensation – Stock Compensation, the fair value of each option grant has been estimated as of the date of grant using the following weighted average assumptions:

	Three Months Ended March 31,
	2022		2021
Risk-free rate	1.64	%	0.75	%
Expected dividends	—		—
Expected term	6 years		6 years
Expected volatility	73.95	%	74.80	%

Stock-based compensation expense is allocated on a departmental basis, based on the classification of the award holder. The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended March 31,
	2022		2021
Research and development	$	587	$	64
Sales and marketing	54		16
General and administrative	2,119		49
Total stock-based compensation	$	2,760	$	129

As of March 31, 2022, there was approximately $24,071 thousand of unamortized stock-based compensation expense related to unvested stock options and RSUs, which was expected to be recognized over a weighted average period of 3.11 years.

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FAIR VALUE MEASUREMENTS

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS

The Company follows ASC 820, Fair Value Measurements, which establishes a common definition of fair value to be applied when U.S. GAAP requires the use of fair value, establishes a framework for measuring fair value, and requires certain disclosure about such fair value measurements. The following table presents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis (in thousands):

March 31, 2022	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents and restricted cash:
Money market funds	$	211,369	$	—	$	—	$	211,369
Certificate of deposit	—		75		—		75
Total assets	$	211,369	$	75	$	—	$	211,444
Liabilities:
Earnout warrant liabilities	$	—	$	636	$	—	$	636
Public common stock warrants	8,042		—		—		8,042
Private common stock warrants	—		3,815		—		3,815
Total liabilities	$	8,042	$	4,451	$	—	$	12,493

December 31, 2021	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents and restricted cash:
Money market funds	$	237,897	$	—	$	—	$	237,897
Certificate of deposit	—		125		—		125
Total assets	$	237,897	$	125	$	—	$	238,022
Liabilities:
Earnout warrant liabilities	$	—	$	1,476	$	—	$	1,476
Public common stock warrants	18,666		—		—		18,666
Private common stock warrants	—		8,855		—		8,855
Total liabilities	$	18,666	$	10,331	$	—	$	28,997

There were no transfers among Level 1, Level 2, or Level 3 categories during the periods presented. The carrying amounts of the Company’s notes payable, and accounts payable approximate their fair values due to their short maturities.

Level 1 Assets:

The Company invests in money market funds that have maturities of 90 days or less. Money market funds are classified as cash equivalents and are recorded at their carrying value, which approximates fair value.

Level 2 Assets:

The Company invests in a certificate of deposit with a maturity of one year from purchase date. The certificate of deposit is classified as restricted cash and is recorded at its carrying value, which approximates fair value.

Level 1 Liabilities:

The Company values its public common stock warrants based on the market price of the warrant.

Level 2 Liabilities:

The Company values its earnout warrant liabilities and private common stock warrants based on the market price of the Company’s public common stock warrants.

Level 3 Liabilities:

Warrants

Freestanding warrants to purchase Redeemable Convertible Preferred Stock were accounted for as liability awards and recorded at fair value on their issuance date and adjusted to fair value at each reporting date, with the change in fair value being recorded as a component of other income (expenses), net. The warrants were accounted for as liabilities as the underlying shares of Preferred Stock were contingently redeemable upon occurrence of a change in control, which was outside the control of the Company.

As of March 31, 2021, the Company measured its warrant liabilities using Level 3 unobservable inputs within the Black-Scholes Merton option-pricing model. The Company used various key assumptions, such as the fair value of Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants, the volatility of peer companies’ stock prices, the risk-free interest rate based on the U.S. Treasury yield, and the expected term (based on remaining term to a significant event for Series B redeemable convertible preferred stock warrants and remaining contractual term for Series C redeemable convertible preferred stock warrants). The Company measured the fair value of the redeemable convertible Preferred Stock warrants at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded through other income (expenses), net in the consolidated statements of operations and comprehensive loss.

Future Rights to Purchase Series C-2 Redeemable Convertible Preferred Stock

See Note 11 for a discussion of the Company’s Series C Redeemable Convertible Preferred Stock financing agreement.

The value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right was determined based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy.

The fair value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right was determined using a discounted cash flow model, which takes into account the estimated value of Series C-2 stock, estimated time to purchase, probability of purchase and the risk-free interest rate based on the U.S. Treasury yield. The Company measures the fair value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded through other expense, net in the consolidated statements of operations and comprehensive loss.

The following table sets forth a summary of changes in the fair value of the Company’s Level 3 liabilities at fair value on a recurring basis (in thousands):

	Three Months Ended March 31,
	2022		2021
Warrant liabilities:
Beginning balance December 31	$	—	$	3,329
Change in fair value	—		8,426
Fair value of warrants issued	—		5,096
Fair value of warrants exercised	—		(356)
Ending balance March 31	—		16,495
Series C-2 Convertible Preferred Stock Issuance Right liability:
Beginning balance December 31	—		22,911
Change in fair value	—		138,141
Fair value of derivatives extinguished	—		(23,152)
Ending balance March 31	—		137,900
Total	$	—	$	154,395

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INCOME TAXES	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXESThe Company did not record a tax provision for the three months ended March 31, 2022 and 2021, respectively, due to the Company’s history of losses, and accordingly, has recorded a valuation allowance against substantially all of the Company’s net deferred tax assets. The Company provides for a valuation allowance when it is more likely than not that some portion of, or all of the Company’s deferred tax assets will not be realized.

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RELATED PARTY TRANSACTIONS

3 Months Ended

Mar. 31, 2022

Related Party Transactions [Abstract]

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS

In April 2021, the Company signed a framework agreement with one of its investors, SB Energy Global Holdings One Ltd (“SBE”), to supply energy storage products to SBE in support of its market activities. Under this agreement, the Company has made various commitments to meet SBE’s potential need for energy storage products and is obligated to reserve a certain percentage of manufacturing capacity to meet SBE’s future needs, subject to periodic reviews of its firm and anticipated orders. To date, no orders have been placed under the framework agreement.

Additionally, the Company entered into a preferred financing equity transaction with SBE and Breakthrough Energy Ventures, LLC as discussed in Note 11. These related parties were also issued 6,707,318 of the Earnout Shares discussed in Note 3.

As of December 31, 2021, the Company had recorded accounts receivable of $66 thousand and deferred revenue of $171 thousand for sales of Energy Warehouse products to related parties.

As of March 31, 2022, the Company had recorded deferred revenue of $237 thousand for sales of Energy Warehouse products to related parties.

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SIGNIFICANT ACCOUNTING POLICIES (Policies)

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation—The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Pursuant to the Merger Agreement, the merger between Merger Sub and Legacy ESS was accounted for as a reverse recapitalization in accordance with U.S. GAAP (the “Reverse Recapitalization”). Under this method of accounting, STWO was treated as the “acquired” company and Legacy ESS was treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Reverse Recapitalization was treated as the equivalent of Legacy ESS issuing stock for the net assets of STWO, accompanied by a recapitalization. The net assets of STWO were stated at historical cost, with no goodwill or other intangible assets recorded. Legacy ESS was determined to be the accounting acquirer based on the following predominant factors:

•Legacy ESS’s existing stockholders had the greatest voting interest in the Company;

•Legacy ESS’s directors represented all of the new board of directors of the Company;

•Legacy ESS’s senior management continued as the senior management of the Company; and,

•Legacy ESS had the larger employee base.

The assets, liabilities and results of operations prior to the Reverse Recapitalization are those of Legacy ESS. The shares and corresponding capital amounts and losses per share, prior to the Reverse Recapitalization, have been retroactively restated based on shares reflecting the exchange ratio of approximately 1.47 (the “Per Share Consideration”) established in the Business Combination.

Reclassifications

Reclassifications—Certain prior year amounts have been reclassified to conform with current year presentation.

Use of Estimates

Use of Estimates—The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Such estimates relate to, among others, the useful lives and assessment of recoverability of property and equipment, deferred tax assets valuation, determination of the fair value of the Company’s earnout warrant liabilities and private warrants, as well as other accruals. These estimates are based on historical trends, market pricing, current events and other relevant assumptions and data points. Actual results could differ from those estimates and such differences may be material to the consolidated financial statements.

Net Loss per Share

Net Loss Per Share—The Company follows the two-class method when computing net income (loss) per common share when shares are issued that meet the definition of participating securities. Under this method, net earnings are reduced by the amount of dividends declared in the current period for common shareholders and participating security holders. The remaining earnings or “undistributed earnings” are allocated between common stock and participating securities to the extent that each security may share in earnings as if all the earnings for the period had been distributed. Once calculated, the earnings per common share is computed by dividing the net income (loss) attributable to common shareholders by the weighted average number of common shares outstanding during each year presented. Diluted income (loss) attributable to common shareholders per common share has been computed by dividing the net income (loss) attributable to common shareholders by the weighted average number of common shares outstanding plus the dilutive effect of outstanding options, warrants, and restricted stock units (“RSU”) during the respective periods computed using the treasury method. In cases where the Company has a net loss, no dilutive effect is shown as options, warrants, RSU, and earnout shares pending satisfaction of a regulatory holding period become anti-dilutive.

Cash, Cash Equivalents, and Restricted Cash

Cash and Cash Equivalents—The Company considers all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents. Cash equivalents are recorded at carrying value, which approximates fair value. Cash and cash equivalents include cash in bank accounts and money market funds.

Restricted Cash—Restricted cash is required as collateral for certain of the Company’s lease agreements and contractual supply and service arrangements. Restricted cash includes a certificate of deposit for the Company’s lease agreements and a performance and payment bond for the Company’s supply and service arrangements. The certificate of deposit and bond are recorded at carrying value, which approximates fair value. Restricted cash amounts are reported in the consolidated balance sheets as current or non-current depending on when the cash will be contractually released.

Revenue Recognition

Revenue Recognition—The Company did not recognize any revenue in either of the three month periods ended March 31, 2022 or 2021. The Company will recognize revenue in accordance with the requirements of, and the guidance provided by Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers (Topic 606).

Stock-Based Compensation

Stock-Based Compensation—The Company accounts for stock-based compensation in accordance with ASC 718, Compensation – Stock Compensation. The Company measures and recognizes compensation expense for all stock-based awards based on estimated fair values on the date of the grant, recognized over the requisite service period. For awards that vest solely based on a service condition, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period. The compensation expense related to awards with performance conditions is recognized over the requisite service period when the performance conditions are probable of being achieved. The compensation expense related to awards with market conditions is recognized on an accelerated attribution basis over the requisite service period identified as the derived service period over which the market conditions are expected to be achieved, and is not reversed if the market condition is not satisfied. The Company accounts for forfeitures as they occur. Stock-based awards granted to employees are primarily stock options and RSUs.

The fair value of each stock option granted is estimated using the Black-Scholes Merton option-pricing model using the single-option award approach. The following assumptions are used in the Black-Scholes Merton option-pricing model:

Risk-Free Interest Rate—The risk-free interest rate is based on the implied yield available on the date of grant on U.S. Treasury zero-coupon issued with a term that is equal to the option’s expected term at the grant date.

Expected Volatility—The Company estimates the volatility for option grants by evaluating the average historical volatility of a peer group of companies for the period immediately preceding the option grant for a term that is approximately equal to the option’s expected term.

Expected Term—The expected term for employees represents the period over which options granted are expected to be outstanding using the simplified method, as the Company’s historical share option exercise experience does not provide a reasonable basis upon which to estimate the expected term. The simplified method deems the term to be the average of the time-to-vesting and contractual life of the stock-based awards.

Dividend Yield—The Company has not declared or paid dividends to date and does not anticipate declaring dividends. As such, the dividend yield has been estimated to be zero.

Fair Value

Fair Value—The Company follows ASC 820, Fair Value Measurements (“ASC 820”), which establishes a common definition of fair value to be applied when U.S. GAAP requires the use of fair value, establishes a framework for measuring fair value, and requires certain disclosure about such fair value measurements.

ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about what market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs as follows:

Level 1: Observable inputs such as quoted prices in active markets for identical assets or liabilities to which the Company has access at a measurement date.

Level 2: Observable inputs other than Level 1 quoted prices that are observable for the asset or liability, either directly or indirectly; these include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3: Unobservable inputs for which little or no market data exists and for which the Company must develop its own assumptions regarding the assumptions that market participants would use in pricing the asset or liability, including assumptions regarding risk.

Because of the uncertainties inherent in the valuation of assets or liabilities for which there are no observable inputs, those estimated fair values may differ significantly from the values that may have been used had a ready market for the assets or liabilities existed.

Recent Accounting Pronouncements

Recent Accounting Pronouncements—Pursuant to the Jumpstart Our Business Startups Act (“JOBS Act”), an emerging growth company is provided the option to adopt new or revised accounting standards that may be issued by the FASB or the SEC either (i) within the same periods as those otherwise applicable to non-emerging growth companies or (ii) within the same time periods as private companies. The Company has elected to use the extended transition period for complying with any new or revised financial accounting standards. As a result, the Company’s consolidated financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective date for new or revised accounting standards that are applicable to public companies. The Company also intends to continue to take advantage of some of the reduced regulatory and reporting requirements of emerging growth companies pursuant to the JOBS Act so long as the Company qualifies as an emerging growth company.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with a forward-looking expected credit loss model, which will result in earlier recognition of credit losses. ASU 2016-13 is effective for emerging growth companies for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The Company is currently evaluating the impact that the standard will have on its consolidated financial statements and related disclosures.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes. ASU 2019-12 is effective for emerging growth companies for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. The Company is currently evaluating the impact that the standard will have on its consolidated financial statements and related disclosures.

Recently Adopted Accounting Pronouncements—On January 1, 2022, the Company adopted ASU 2016-02, Leases (ASC 842), which superseded previous guidance related to accounting for leases within Topic 840, Leases. The Company elected the practical expedient provided under ASU 2018-11, Leases (Topic 842) Targeted Improvements, which amended ASU 2016-02 to provide entities an optional transition practical expedient to adopt the new standard with a cumulative effect adjustment as of the beginning of the year of adoption with prior year comparative financial information and disclosures remaining as previously reported. As a result, no adjustments were made to the consolidated balance sheet prior to January 1, 2022 and amounts are reported in accordance with historical accounting under Topic 840, while the consolidated balance sheet as of March 31, 2022 is presented under Topic 842.

The Company elected the package of practical expedients permitted under the transition guidance, which allowed it to carry forward historical lease classification, assessment on whether a contract was or contains a lease, and assessment of initial direct costs for any leases that existed prior to January 1, 2022. The Company also elected to combine its lease and non-lease components and to keep leases with an initial term of 12 months or less off the consolidated balance sheet and recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term.

For new required disclosures and further information see Note 8, Leases. Adoption of the new standard resulted in the recording of lease assets and lease liabilities of $4,534 thousand and $5,229 thousand, respectively, as of January 1, 2022. The transition did not have a material impact on the Company’s results of operations, cash flows or liquidity measures.

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NET LOSS PER SHARE (Tables)

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss per Share Attributable to Common Shareholders

The following table presents the calculation of basic and diluted net loss per share attributable to common stockholders (in thousands, except per share data):

	Three Months Ended March 31,
	2022		2021
Net loss attributable to common stockholders	$	(5,709)	$	(154,918)
Weighted-average shares outstanding – Basic and Diluted	151,683,819		61,693,067
Net loss per share – Basic and Diluted	$	(0.04)	$	(2.51)

Schedule of Securities Excluded from Calculation of Diluted Weighted-Average Common Shares Outstanding

The following outstanding balances of common share equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented:

	March 31, 2022	March 31, 2021
Stock options	3,707,113	4,379,633
RSUs	4,633,968	—
Warrants	11,461,227	3,362,047
Number of securities outstanding	19,802,308	7,741,680

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PREPAID EXPENSES AND OTHER CURRENT ASSETS (Tables)

3 Months Ended

Mar. 31, 2022

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Insurance	$	2,397	$	3,482
Vendor advances	1,514		1,103
Other	495		259
Total prepaid expenses and other current assets	$	4,406	$	4,844

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PROPERTY AND EQUIPMENT, NET (Tables)

3 Months Ended

Mar. 31, 2022

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, net

Property and equipment, net consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Machinery and equipment	$	2,910	$	2,868
Furniture and fixtures	88		90
Leasehold improvements	1,030		746
Construction in process	7,944		2,517
Total property and equipment	11,972		6,221
Less accumulated depreciation	(1,916)		(1,720)
Total property and equipment, net	$	10,056	$	4,501

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ACCRUED AND OTHER CURRENT LIABILITIES (Tables)

3 Months Ended

Mar. 31, 2022

Payables and Accruals [Abstract]

Schedule of Accrued and Other Current Liabilities

Accrued and other current liabilities consist of the following (in thousands):

	March 31, 2022		December 31, 2021
Payroll and related benefits	$	1,552	$	1,876
Materials and related purchases	2,596		2,108
Deferred rent	—		142
Professional and consulting fees	1,140		1,820
Other	1,327		541
Total accrued and other current liabilities	$	6,615	$	6,487

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LEASES (Tables)

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

Finance Lease Liability Maturities

As of March 31, 2022 future maturities of lease liabilities are as follows (in thousands):

	Operating Leases		Finance Leases
2022	$	1,222	$	21
2023	1,670		30
2024	1,720		30
2025	983		30
2026	—		30
Thereafter	—		7
Total minimum lease payments	$	5,595	$	148
Less imputed interest	(673)		(25)
Total	$	4,922	$	123

Operating Lease Liability Maturities

As of March 31, 2022 future maturities of lease liabilities are as follows (in thousands):

	Operating Leases		Finance Leases
2022	$	1,222	$	21
2023	1,670		30
2024	1,720		30
2025	983		30
2026	—		30
Thereafter	—		7
Total minimum lease payments	$	5,595	$	148
Less imputed interest	(673)		(25)
Total	$	4,922	$	123

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BORROWINGS (Tables)

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Schedule of Long Term Debt

Long term debt consists of the following (in thousands):

	March 31, 2022		December 31, 2021
Total notes payable	$	3,300	$	3,769
Less current portion of notes payable	1,817		1,900
Notes payable, non-current	$	1,483	$	1,869

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LEGACY ESS REDEEMABLE CONVERTIBLE PREFERRED STOCK (Tables)

3 Months Ended

Mar. 31, 2022

Temporary Equity Disclosure [Abstract]

Schedule of Warrants

The number of shares subject to and potential proceeds from the C-2 Redeemable Convertible Preferred Stock Purchase Agreement and related C-2 Warrants were as follows:

	As of May 7, 2021
	Upon completion of the Business Combination
	Quantity	Price
Series C-2 Redeemable Convertible Preferred Stock Purchase Right	7,994,442	$	2.00
Series C-2 Warrant exercisable upon completion of the Business Combination	21,159,364	$	0.00007

The table below shows the common stock warrant activities during the three months ended March 31, 2022:

	December 31, 2021	Issued	Exercised	March 31, 2022
Earnout Warrants	583,334	—	—	583,334
Public Warrants	7,377,913	—	20	7,377,893
Private Warrants	3,500,000	—	—	3,500,000
Total Common Stock Warrants	11,461,247	—	20	11,461,227

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COMMON STOCK WARRANTS (Tables)

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Schedule of Common Stock Warrant Activity

The number of shares subject to and potential proceeds from the C-2 Redeemable Convertible Preferred Stock Purchase Agreement and related C-2 Warrants were as follows:

	As of May 7, 2021
	Upon completion of the Business Combination
	Quantity	Price
Series C-2 Redeemable Convertible Preferred Stock Purchase Right	7,994,442	$	2.00
Series C-2 Warrant exercisable upon completion of the Business Combination	21,159,364	$	0.00007

The table below shows the common stock warrant activities during the three months ended March 31, 2022:

	December 31, 2021	Issued	Exercised	March 31, 2022
Earnout Warrants	583,334	—	—	583,334
Public Warrants	7,377,913	—	20	7,377,893
Private Warrants	3,500,000	—	—	3,500,000
Total Common Stock Warrants	11,461,247	—	20	11,461,227

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STOCK-BASED COMPENSATION PLAN (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Schedule of Share-based Payment Arrangement, Option, Activity

Stock option and RSU activity, prices, and values during the three months ended March 31, 2022 is as follows (in thousands, except for share, per share, and contractual term data):

	Options Outstanding						RSUs
	Number of shares	Weighted average exercise price		Weighted average remaining  contractual term (years)	Aggregate intrinsic values ($'000s)		Number of plan shares outstanding	Weighted average grant date fair value per Share
Balances as of December 31, 2021	3,796,530	$	0.83	8.08	$	40,274	3,392,153	$	10.69
Options and RSUs granted	65,717	8.00					2,150,859	5.46
Options exercised and RSUs released	(138,617)	0.30					(873,070)	11.12
Options and RSUs forfeited	(16,517)	0.36					(35,974)	10.15
Balances as of March 31, 2022	3,707,113	$	0.98	8.03	$	17,012	4,633,968	$	8.82
Options vested and exercisable - December 31, 2021	1,827,374	$	0.31	7.20	$	20,337
Options vested and exercisable - March 31, 2022	1,626,013	$	0.56	7.41	$	8,140

Schedule of Share-based Payment Arrangement, Restricted Stock Unit, Activity

Stock option and RSU activity, prices, and values during the three months ended March 31, 2022 is as follows (in thousands, except for share, per share, and contractual term data):

	Options Outstanding						RSUs
	Number of shares	Weighted average exercise price		Weighted average remaining  contractual term (years)	Aggregate intrinsic values ($'000s)		Number of plan shares outstanding	Weighted average grant date fair value per Share
Balances as of December 31, 2021	3,796,530	$	0.83	8.08	$	40,274	3,392,153	$	10.69
Options and RSUs granted	65,717	8.00					2,150,859	5.46
Options exercised and RSUs released	(138,617)	0.30					(873,070)	11.12
Options and RSUs forfeited	(16,517)	0.36					(35,974)	10.15
Balances as of March 31, 2022	3,707,113	$	0.98	8.03	$	17,012	4,633,968	$	8.82
Options vested and exercisable - December 31, 2021	1,827,374	$	0.31	7.20	$	20,337
Options vested and exercisable - March 31, 2022	1,626,013	$	0.56	7.41	$	8,140

Schedule of Valuation Assumptions

In accordance with ASC 718, Compensation – Stock Compensation, the fair value of each option grant has been estimated as of the date of grant using the following weighted average assumptions:

	Three Months Ended March 31,
	2022		2021
Risk-free rate	1.64	%	0.75	%
Expected dividends	—		—
Expected term	6 years		6 years
Expected volatility	73.95	%	74.80	%

Schedule of Stock-Based Compensation

The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended March 31,
	2022		2021
Research and development	$	587	$	64
Sales and marketing	54		16
General and administrative	2,119		49
Total stock-based compensation	$	2,760	$	129

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FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis

The following table presents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis (in thousands):

March 31, 2022	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents and restricted cash:
Money market funds	$	211,369	$	—	$	—	$	211,369
Certificate of deposit	—		75		—		75
Total assets	$	211,369	$	75	$	—	$	211,444
Liabilities:
Earnout warrant liabilities	$	—	$	636	$	—	$	636
Public common stock warrants	8,042		—		—		8,042
Private common stock warrants	—		3,815		—		3,815
Total liabilities	$	8,042	$	4,451	$	—	$	12,493

December 31, 2021	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents and restricted cash:
Money market funds	$	237,897	$	—	$	—	$	237,897
Certificate of deposit	—		125		—		125
Total assets	$	237,897	$	125	$	—	$	238,022
Liabilities:
Earnout warrant liabilities	$	—	$	1,476	$	—	$	1,476
Public common stock warrants	18,666		—		—		18,666
Private common stock warrants	—		8,855		—		8,855
Total liabilities	$	18,666	$	10,331	$	—	$	28,997

Schedule of Changes in Fair Value Liabilities on Recurring Basis

The following table sets forth a summary of changes in the fair value of the Company’s Level 3 liabilities at fair value on a recurring basis (in thousands):

	Three Months Ended March 31,
	2022		2021
Warrant liabilities:
Beginning balance December 31	$	—	$	3,329
Change in fair value	—		8,426
Fair value of warrants issued	—		5,096
Fair value of warrants exercised	—		(356)
Ending balance March 31	—		16,495
Series C-2 Convertible Preferred Stock Issuance Right liability:
Beginning balance December 31	—		22,911
Change in fair value	—		138,141
Fair value of derivatives extinguished	—		(23,152)
Ending balance March 31	—		137,900
Total	$	—	$	154,395

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DESCRITPION OF BUSINESS AND BASIS OF PRESENTATION (Details)	Oct. 08, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recapitalization exchange ratio	0.0147

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SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Jan. 01, 2022	Dec. 31, 2021
Significant Accounting Policies [Line Items]
Operating lease right-of-use assets	$ 4,260			$ 0
Total	$ 4,922
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease right-of-use assets			$ 4,534
Total			$ 5,229
Stock options
Significant Accounting Policies [Line Items]
Expected dividends	0.00%	0.00%

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BUSINESS COMBINATION (Details) - $ / shares	Nov. 09, 2021	Oct. 08, 2021	Mar. 31, 2022	Dec. 31, 2021	Oct. 07, 2021
Business Acquisition [Line Items]
Common stock, par value (in USD per share)		$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, par value (in USD per share)		$ 0.0001	$ 0.0001	$ 0.0001
Common and preferred stock authorized (in shares)		2,200,000,000
Common stock, shares authorized (in shares)		2,000,000,000	2,000,000,000	2,000,000,000
Preferred stock, shares authorized (in shares)		200,000,000	200,000,000	200,000,000
Common Stock
Business Acquisition [Line Items]
Shares issuable under contingent consideration (in shares)		16,500,000
Legacy ESS
Business Acquisition [Line Items]
Common stock, par value (in USD per share)					$ 0.0001
Preferred stock, par value (in USD per share)					$ 0.0001
Legacy ESS | Common Stock
Business Acquisition [Line Items]
Shares issued upon completion of milestones (in shares)	15,674,965
Legacy ESS Shareholders
Business Acquisition [Line Items]
Shares issued (in shares)		99,700,326
Legacy ESS Shareholders | Transaction Expense Adjustment
Business Acquisition [Line Items]
Shares issued (in shares)		125,958

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NET LOSS PER SHARE - Schedule of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Net loss to common stockholders, diluted	$ (5,709)	$ (154,918)
Net loss to common stockholders, basic	$ (5,709)	$ (154,918)
Weighted average shares used in per share calculation, basic (in shares)	151,683,819	61,693,067
Weighted average shares used in per share calculation, diluted (in shares)	151,683,819	61,693,067
Net loss per share, diluted (in USD per share)	$ (0.04)	$ (2.51)
Net loss per share, basic (in USD per share)	$ (0.04)	$ (2.51)

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NET LOSS PER SHARE - Schedule Antidilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of securities outstanding (in shares)	19,802,308	7,741,680
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of securities outstanding (in shares)	3,707,113	4,379,633
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of securities outstanding (in shares)	4,633,968	0
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of securities outstanding (in shares)	11,461,227	3,362,047

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PREPAID EXPENSES AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Insurance	$ 2,397	$ 3,482
Vendor advances	1,514	1,103
Other	495	259
Total prepaid expenses and other current assets	$ 4,406	$ 4,844

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PROPERTY AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 11,972		$ 6,221
Less accumulated depreciation	(1,916)		(1,720)
Total property and equipment, net	10,056		4,501
Depreciation expense	196	$ 130
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	2,910		2,868
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	88		90
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	1,030		746
Construction in process
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 7,944		$ 2,517

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ACCRUED AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Payroll and related benefits	$ 1,552	$ 1,876
Materials and related purchases	2,596	2,108
Deferred rent	0	142
Professional and consulting fees	1,140	1,820
Other	1,327	541
Total accrued and other current liabilities	$ 6,615	$ 6,487

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LEASES - Narrative (Details)	3 Months Ended
	Mar. 31, 2022 USD ($)
Leases [Abstract]
Short-term lease cost	$ 0
Renewal term	60 months
Operating lease cost	$ 371,000
Operating lease, weighted average remaining term	3 years 4 months 24 days
Operating lease, weighted average discount rate	7.50%
Finance lease, weighted average remaining term	4 years 10 months 24 days
Operating lease, weighted average discount rate	7.50%

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LEASES- Maturities of Operating and Financing Lease Liabilities (Details) $ in Thousands	Mar. 31, 2022 USD ($)
Operating Leases
2022	$ 1,222
2023	1,670
2024	1,720
2025	983
2026	0
Thereafter	0
Total minimum lease payments	5,595
Less imputed interest	(673)
Total	4,922
Finance Leases
2022	21
2023	30
2024	30
2025	30
2026	30
Thereafter	7
Total minimum lease payments	148
Less imputed interest	(25)
Total	$ 123

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BORROWINGS - Schedule of Long Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
Total notes payable	$ 3,300	$ 3,769
Less current portion of notes payable	1,817	1,900
Notes payable, non-current	$ 1,483	$ 1,869

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BORROWINGS - Narrative (Details) - Notes Payable $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Debt amount			$ 4,000	$ 1,000
Gain (loss) on extinguishment of debt		$ (62)
Percent change in present value of cash flows			0.10
Effective interest rate	3.00%
Prime
Debt Instrument [Line Items]
Spread on interest rate	0.50%

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COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Other Commitments [Line Items]
Restricted certificate of deposit	$ 75
Noncancellable Agreement
Other Commitments [Line Items]
Noncancelable purchase commitments	23,344		$ 10,160
Cancellable Agreement
Other Commitments [Line Items]
Noncancelable purchase commitments	3,539		10,446
Letter of Credit | First Republic Bank
Other Commitments [Line Items]
Standby letter of credit	725		$ 725
Draws against letter of credit	$ 0	$ 0

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LEGACY ESS REDEEMABLE CONVERTIBLE PREFERRED STOCK - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended
	Oct. 08, 2021 USD ($) $ / shares	Oct. 07, 2021 USD ($) $ / shares shares	Mar. 31, 2021 USD ($) $ / shares shares	Mar. 31, 2022 USD ($) shares	Mar. 31, 2021 USD ($) $ / shares	Dec. 31, 2021 USD ($) shares	May 07, 2021 $ / shares	Dec. 31, 2020 USD ($)
Temporary Equity [Line Items]
Recapitalization exchange ratio	0.0147
Fair value of temporary equity			$ 0	$ 0	$ 0	$ 0		$ 0
Value of share issued					29,516
Warrants issued (in shares) | shares				0
Warrants exercised (in shares) | shares				20
Increase in derivative liability				$ 0	(138,141)
Warrants (in shares) | shares				11,461,227		11,461,247
Series C-2 Redeemable Convertible Preferred Stock Purchase Rights And Warrants
Temporary Equity [Line Items]
Stock issuance costs	$ 439
Proceeds from transaction	$ 15,559
Legacy ESS
Temporary Equity [Line Items]
Transaction value			$ 34,613		$ 34,613
Warrants term		10 years
Legacy ESS | Series C-2 Redeemable Convertible Preferred Stock Purchase Right
Temporary Equity [Line Items]
Fair value of temporary equity		$ 11,379
Warrants issued (in shares) | shares			861,896
Warrants exercised (in shares) | shares			5,746,003
Warrant exercise price (in USD per share) | $ / shares			$ 0.0001		$ 0.0001
Legacy ESS | Series C-2 Redeemable Convertible Preferred Stock Warrants
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares							$ 0.00007
Warrants term		10 years
Legacy ESS | Series C-2 Redeemable Convertible Preferred Stock Warrants | Minimum
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares		$ 0.00007
Legacy ESS | Series C-2 Redeemable Convertible Preferred Stock Warrants | Maximum
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares		$ 1.25
Legacy ESS | Series B Redeemable Convertible Preferred Stock Warrants
Temporary Equity [Line Items]
Warrants (in shares) | shares		100,161
Legacy ESS | Series B Redeemable Convertible Preferred Stock Warrants | Minimum
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares		$ 0.0007
Legacy ESS | Series B Redeemable Convertible Preferred Stock Warrants | Maximum
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares		$ 0.83
Legacy ESS | Series C-1 Redeemable Convertible Preferred Stock Warrants
Temporary Equity [Line Items]
Warrants term		10 years
Legacy ESS | Series C-1 Redeemable Convertible Preferred Stock Warrants | Minimum
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares		$ 0.00007
Legacy ESS | Series C-1 Redeemable Convertible Preferred Stock Warrants | Maximum
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares		1.25
Legacy ESS | Common Stock Warrants
Temporary Equity [Line Items]
Warrant exercise price (in USD per share) | $ / shares		$ 0.0007
Common Stock
Temporary Equity [Line Items]
Conversion of convertible shares (in shares) | shares		57,104,332
Price per share (in USD per share) | $ / shares	$ 11.50
Series C-2 Redeemable Convertible Preferred Stock | Legacy ESS
Temporary Equity [Line Items]
Committed funding amount		$ 79,999
Committed purchase of shares (in shares) | shares		39,971,716
Committed price per share (in USD per share) | $ / shares		$ 2.00
Shares issued (in shares) | shares			5,746,003
Price per share (in USD per share) | $ / shares			$ 2.00		$ 2.00
Value of share issued			$ 11,500
Stock issuance costs			39
Derivative liability			23,152		$ 23,152
Transaction value			29,516		29,516
Warrants | Legacy ESS
Temporary Equity [Line Items]
Transaction value			$ 5,096		$ 5,096

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LEGACY ESS REDEEMABLE CONVERTIBLE PREFERRED STOCK - Schedule of Rights and Warrants (Details) - Legacy ESS	May 07, 2021 $ / shares shares
Series C-2 Redeemable Convertible Preferred Stock Purchase Right
Class of Warrant or Right [Line Items]
Shares issued (in shares) | shares	7,994,442
Price per share (in USD per share) | $ / shares	$ 2.00
Series C-2 Warrant exercisable upon completion of the Business Combination
Class of Warrant or Right [Line Items]
Shares issued (in shares) | shares	21,159,364
Price per share (in USD per share) | $ / shares	$ 0.00007

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COMMON STOCK WARRANTS - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	Oct. 08, 2021	Sep. 21, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Nov. 09, 2021
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)			11,461,227		11,461,247
Warrants issued (in shares)			0
Warrants exercised (in shares)			20
Net decrease to warrant liabilities			$ (15,664)	$ 8,426
Redemption Scenario, Two
Class of Warrant or Right [Line Items]
Price of common stock triggering redemption of warrants (in USD per share)			$ 10.00
Price of common stock with trading days threshold, triggering redemption of warrants (in USD per share)			$ 10.00
Trading days triggering redemption of warrants			20 days
Consecutive trading day period			30 days
Common Stock
Class of Warrant or Right [Line Items]
Price per share (in USD per share)	$ 11.50
Common Stock | STWO
Class of Warrant or Right [Line Items]
Price per share (in USD per share)		$ 11.50
Common Stock | Public Warrant Holders | STWO
Class of Warrant or Right [Line Items]
Issuance of shares (in shares)		1
Common Stock | Private Warrant Holders
Class of Warrant or Right [Line Items]
Issuance of shares (in shares)	1
Common Stock | Earnout Warrant Holders
Class of Warrant or Right [Line Items]
Issuance of shares (in shares)	1
Private common stock warrants | Private Placement | STWO | STWO's Sponsor
Class of Warrant or Right [Line Items]
Shares issued (in shares)		4,666,667
Public common stock warrants
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)			7,377,893		7,377,913
Warrants issued (in shares)			0
Warrants exercised (in shares)			20
Net decrease to warrant liabilities			$ 10,624
Public common stock warrants | STWO
Class of Warrant or Right [Line Items]
Warrants issued (in shares)	8,333,287
Warrants term		5 years
Public common stock warrants | Redemption Scenario, One
Class of Warrant or Right [Line Items]
Redemption price per share (in USD per share)			$ 0.01
Price of common stock triggering redemption of warrants (in USD per share)			18.00
Price of common stock with trading days threshold, triggering redemption of warrants (in USD per share)			$ 10.00
Trading days triggering redemption of warrants			20 days
Consecutive trading day period			30 days
Public common stock warrants | Redemption Scenario, Two
Class of Warrant or Right [Line Items]
Redemption price per share (in USD per share)			$ 0.10
Public common stock warrants | Redemption Scenario, Three
Class of Warrant or Right [Line Items]
Price of common stock triggering redemption of warrants (in USD per share)			18.00
Price of common stock with trading days threshold, triggering redemption of warrants (in USD per share)			$ 10.00
Trading days triggering redemption of warrants			20 days
Consecutive trading day period			30 days
Private common stock warrants
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)	4,083,334		3,500,000		3,500,000
Warrants issued (in shares)			0
Warrants vested (in shares)	3,500,000
Warrants exercised (in shares)			0
Net decrease to warrant liabilities			$ 5,040
Private common stock warrants | STWO's Sponsor
Class of Warrant or Right [Line Items]
Warrants forfeited (in shares)	583,333
Earnout Warrants
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)			583,334		583,334
Warrants issued (in shares)			0
Warrants vested (in shares)						583,334
Warrants exercised (in shares)			0
Net decrease to warrant liabilities			$ 840

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COMMON STOCK WARRANTS - Schedule of Common Stock Warrant Activity (Details) - shares		3 Months Ended
	Oct. 08, 2021	Mar. 31, 2022
Class of Warrant or Right [Roll Forward]
Warrants or rights at beginning of period (in shares)		11,461,247
Warrants issued (in shares)		0
Warrants exercised (in shares)		20
Warrants or rights at end of period (in shares)		11,461,227
Earnout Warrants
Class of Warrant or Right [Roll Forward]
Warrants or rights at beginning of period (in shares)		583,334
Warrants issued (in shares)		0
Warrants exercised (in shares)		0
Warrants or rights at end of period (in shares)		583,334
Public Warrants
Class of Warrant or Right [Roll Forward]
Warrants or rights at beginning of period (in shares)		7,377,913
Warrants issued (in shares)		0
Warrants exercised (in shares)		20
Warrants or rights at end of period (in shares)		7,377,893
Private Warrants
Class of Warrant or Right [Roll Forward]
Warrants or rights at beginning of period (in shares)		3,500,000
Warrants issued (in shares)		0
Warrants exercised (in shares)		0
Warrants or rights at end of period (in shares)	4,083,334	3,500,000

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STOCK-BASED COMPENSATION PLAN - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential increase of shares authorized (in shares)	15,260,000
Percentage of potential increase of shares authorized	5.00%
Shares authorized for issuance (in shares)	17,610,000
Award vesting period	3 years
Shares available for future grant (in shares)	13,021,489
Unamortized stock-based compensation costs	$ 24,071
Weighted average period of recognition for unamortized stock-based compensation costs	3 years 1 month 9 days
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)	0
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)	0
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)	4,633,968	3,392,153
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share expiration period	10 years
Non-qualified Stock Options (NSOs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)	0
Incentive Stock Options (ISOs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)	0

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STOCK-BASED COMPENSATION PLAN - Schedule of Share-based Payment Arrangement, Option and RSU Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Options Outstanding
Options outstanding at beginning of period (in shares)	3,796,530
Options granted (in shares)	65,717
Options released (in shares)	(138,617)
Options forfeited (in shares)	(16,517)
Options outstanding at end of period (in shares)	3,707,113	3,796,530
Options vested and exercisable (in shares)	1,626,013	1,827,374
Weighted average exercise price
Weighted average exercise price of options outstanding at beginning of period (in USD per share)	$ 0.83
Weighted average exercise price of options granted (in USD per share)	8.00
Weighted average exercise price of options released (in USD per share)	0.30
Weighted average exercise price of options forfeited (in USD per share)	0.36
Weighted average exercise price of options outstanding at end of period (in USD per share)	0.98	$ 0.83
Weighted average exercise price of options vested and exercisable (in USD per share)	$ 0.56	$ 0.31
Options, Additional Disclosures
Weighted average remaining contractual term of options outstanding	8 years 10 days	8 years 29 days
Weighted average remaining contractual term of options vested and exercisable	7 years 4 months 28 days	7 years 2 months 12 days
Aggregate intrinsic value of options outstanding	$ 17,012	$ 40,274
Aggregate intrinsic value of options vested and exercisable	$ 8,140	$ 20,337
RSUs
RSUs
Units outstanding at beginning of period (in shares)	3,392,153
Units granted (in shares)	2,150,859
Units released (in shares)	(873,070)
Units forfeited (in shares)	(35,974)
Units outstanding at end of period (in shares)	4,633,968	3,392,153
Weighted average grant date fair value per Share
Weighted average grant date fair value per share of units outstanding at beginning of period (in USD per share)	$ 10.69
Weighted average grant date fair value per share of units granted (in USD per share)	5.46
Weighted average grant date fair value per share of units released (in USD per share)	11.12
Weighted average grant date fair value per share of units forfeited (in USD per share)	10.15
Weighted average grant date fair value per share of units outstanding at end of period (in USD per share)	$ 8.82	$ 10.69

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STOCK-BASED COMPENSATION PLAN - Schedule of Valuation Assumptions (Details) - Stock options	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.64%	0.75%
Expected dividends	0.00%	0.00%
Expected term	6 years	6 years
Expected volatility	73.95%	74.80%

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STOCK-BASED COMPENSATION PLAN - Schedule of Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 2,760	$ 129
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	587	64
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	54	16
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 2,119	$ 49

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FAIR VALUE MEASUREMENTS - Schedule of Assets and Liabilities on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets, Fair Value Disclosure [Abstract]
Total assets	$ 211,444	$ 238,022
Liabilities, Fair Value Disclosure [Abstract]
Earnout warrant liabilities	636
Earnout warrant liabilities		1,476
Total liabilities	12,493	28,997
Public common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	8,042	18,666
Private common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	3,815	8,855
Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	211,369	237,897
Certificate of deposit
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	75	125
Level 1
Assets, Fair Value Disclosure [Abstract]
Total assets	211,369	237,897
Liabilities, Fair Value Disclosure [Abstract]
Earnout warrant liabilities	0
Earnout warrant liabilities		0
Total liabilities	8,042	18,666
Level 1 | Public common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	8,042	18,666
Level 1 | Private common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	0	0
Level 1 | Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	211,369	237,897
Level 1 | Certificate of deposit
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	0	0
Level 2
Assets, Fair Value Disclosure [Abstract]
Total assets	75	125
Liabilities, Fair Value Disclosure [Abstract]
Earnout warrant liabilities	636
Earnout warrant liabilities		1,476
Total liabilities	4,451	10,331
Level 2 | Public common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	0	0
Level 2 | Private common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	3,815	8,855
Level 2 | Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	0	0
Level 2 | Certificate of deposit
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	75	125
Level 3
Assets, Fair Value Disclosure [Abstract]
Total assets	0	0
Liabilities, Fair Value Disclosure [Abstract]
Earnout warrant liabilities	0
Earnout warrant liabilities		0
Total liabilities	0	0
Level 3 | Public common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	0	0
Level 3 | Private common stock warrants
Liabilities, Fair Value Disclosure [Abstract]
Common stock warrants	0	0
Level 3 | Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	0	0
Level 3 | Certificate of deposit
Assets, Fair Value Disclosure [Abstract]
Cash equivalents and restricted cash:	$ 0	$ 0

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FAIR VALUE MEASUREMENTS - Schedule of Changes in Fair Value Liabilities on Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at end of period	$ 0	$ 154,395
Warrant liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	0	3,329
Fair value of warrants issued	0	5,096
Change in fair value	0	8,426
Fair value of warrants exercised	0	(356)
Balance at end of period	0	16,495
Redeemable Convertible Preferred Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	0	22,911
Change in fair value	0	138,141
Fair value of derivatives extinguished	0	(23,152)
Balance at end of period	$ 0	$ 137,900

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INCOME TAXES - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income tax expense provision	$ 0	$ 0

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RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Thousands	Nov. 09, 2021	Mar. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Deferred revenue		$ 6,859	$ 3,663
Common Stock | Legacy ESS
Related Party Transaction [Line Items]
Shares issued to related parties (in shares)	15,674,965
Related parties | Common Stock | Legacy ESS
Related Party Transaction [Line Items]
Shares issued to related parties (in shares)	6,707,318
Energy Warehouse Sales
Related Party Transaction [Line Items]
Accounts receivable from related party			66
Deferred revenue		$ 237	$ 171