Nature of Business, Liquidity, Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation We have prepared the unaudited condensed consolidated financial statements included herein pursuant to the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"), and as permitted by those rules, the condensed consolidated financial statements do not include all disclosures required by generally accepted accounting principles as applied in the United States (“U.S. GAAP”). However, we believe that the disclosures herein are adequate to ensure the information presented is not misleading. The condensed consolidated balance sheets as of September 30, 2020 and December 31, 2019 (the latter has been derived from the audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019), and the condensed consolidated statements of operations, of comprehensive loss, of redeemable noncontrolling interest, total stockholders' deficit and noncontrolling interest, and of cash flows for the periods ended September 30, 2020 and 2019, and related notes, should be read in conjunction with the audited financial statements and the notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, as filed with the SEC on March 31, 2020. We believe that all necessary adjustments, which consisted only of normal recurring items, have been included in the accompanying financial statements to fairly state the results of the interim periods. The results of operations for the interim periods presented are not necessarily indicative of the operating results to be expected for any subsequent interim period or for our fiscal year ending December 31, 2020.
Principles of Consolidation	Principles of Consolidation These condensed consolidated financial statements reflect our accounts and operations and those of our subsidiaries in which we have a controlling financial interest. We use a qualitative approach in assessing the consolidation requirement for each of our variable interest entities ("VIEs"), which we refer to as a tax equity partnership (each such VIE, also referred to as our power purchase agreement entities ("PPA Entities")). This approach focuses on determining whether we have the power to direct those activities of the PPA Entities that most significantly affect their economic performance and whether we have the obligation to absorb losses, or the right to receive benefits, that could potentially be significant to the PPA Entities. For all periods presented, we have determined that we are the primary beneficiary in all of our operational PPA Entities, as discussed in Note 13, Power Purchase Agreement Programs. We evaluate our relationships with the PPA Entities on an ongoing basis to ensure that we continue to be the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and the accompanying notes. The most significant estimates include the determination of the stand-alone selling price, including material rights estimates, inventory valuation, specifically excess and obsolescence provisions for obsolete or unsellable inventory and, in relation to property, plant and equipment (specifically Energy Servers), assumptions relating to economic useful lives and impairment assessments. Other accounting estimates include variable consideration relating to product performance guaranties, assumptions to compute the fair value of debt financings, lease and non-lease components and related financing obligations such as incremental borrowing rates, estimated output, efficiency and residual value of the Energy Servers, warranty, product performance guaranties and extended maintenance, derivative valuations, estimates for recapture of U.S. Treasury grants and similar grants, estimates relating to contractual indemnities provisions, estimates for income taxes and deferred tax asset valuation allowances, and stock-based compensation costs. The full extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations and financial condition, including sales, expenses, our allowance for doubtful accounts, stock-based compensation, the carrying value of our long-lived assets, inventory, financial assets, and valuation allowances for tax assets, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning the COVID-19 pandemic and the actions taken to contain it or treat it, as well as the economic impact on local, regional, national and international customers, suppliers and markets. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods as new information becomes available. Actual results could differ materially from these estimates under different assumptions and conditions.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Other than the adoption of the accounting guidance mentioned below, there have been no other significant changes in our reported financial position or results of operations and cash flows resulting from the adoption of new accounting pronouncements. Accounting Guidance Implemented in 2020 Fair Value Measurement - In August 2018, the Financial Accounting Standards Board ("FASB") issued ASU 2018-13, Fair Value Measurement Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement ("ASU 2018-13"). ASU 2018-13 has eliminated, amended and added disclosure requirements for fair value measurements. Entities will no longer be required to disclose the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy, the policy of timing of transfers between levels of the fair value hierarchy and the valuation processes for Level 3 fair value measurements. Companies will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 was effective for annual and interim periods beginning after December 15, 2019. Early adoption was permitted. We adopted ASU 2018-13 as of January 1, 2020 and the adoption did not have a material effect on our financial statements and related disclosures. Stock Compensation - In June 2018, FASB issued ASU 2018-07, Compensation - Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"), which aligns the accounting for share-based payment awards issued to employees and nonemployees. Measurement of equity-classified nonemployee awards will now be valued on the grant date and will no longer be remeasured through the performance completion date. ASU 2018-07 also changes the accounting for nonemployee awards with performance conditions to recognize compensation cost when achievement of the performance condition is probable, rather than upon achievement of the performance condition, as well as eliminating the requirement to reassess the equity or liability classification for nonemployee awards upon vesting, except for certain award types. ASU 2018-07 was effective for us for interim and annual reporting periods beginning after December 15, 2019. Early adoption was permitted. We adopted ASU 2018-07 using a modified retrospective approach on January 1, 2020 and the adoption of ASU 2018-07 did not have a material effect on our financial statements and related disclosures. Accounting Guidance Not Yet Adopted We will no longer be an emerging growth company as of December 31, 2020, after which we will not be able to take advantage of the reduced disclosure requirements applicable to emerging growth companies. As a result, we expect to adopt the guidance below regarding Leases and Financial Instruments on a modified retrospective basis on December 31, 2020 and to reflect the adoption as of January 1, 2020 in our annual results for the period ended December 31, 2020. Leases - In February 2016, FASB issued ASU 2016-02, Leases (Topic 842), as amended (“ASC 842”), which provides new authoritative guidance on lease accounting. Among its provisions, the standard changes the definition of a lease, requires lessees to recognize right-of-use ("ROU") assets and lease liabilities on the balance sheet for operating leases and also requires additional qualitative and quantitative disclosures about lease arrangements. All leases in scope will be classified as either operating or financing. Operating and financing leases will require the recognition of an asset and liability to be measured at the present value of the lease payments. ASC 842 also makes a distinction between operating and financing leases for purposes of reporting expenses on the income statement. We are the lessee under various agreements for facilities and equipment that are currently accounted for as operating leases and expect to continue to enter into new such leases. Additionally, we expect to continue to enter into Managed Services related financing leases in the future and be the lessor of Energy Servers that are subject to power purchase agreements ("PPAs") with customers under our Managed Services Program and our PPA Program that are currently accounted for as leases. ASC 842 provides a number of optional practical expedients in transition. We will elect the package of practical expedients, which permits us to (1) not reassess whether existing contracts contain leases, (2) carryforward the existing lease classification, and (3) not reassess initial direct costs associated with existing leases. While we continue to evaluate the effect of adopting ASC 842, we expect that these new standards will not have a material impact to our financial position. We expect to recognize ROU assets and lease liabilities on the consolidated balance sheets with corresponding ROU assets in the range of $24 million to $30 million and lease liabilities in the range of $36 million to $44 million based on the present value of the remaining minimum rental payments under current leasing standards for existing operating leases. While we do not expect that the adoption of ASC 842 will have a material effect on operating income (loss) and net cash flows, it will however impact the classification between cash flows from operations and cash flows from financing activities on the consolidated statements of cash flows. Financial Instruments - In June 2016, FASB issued ASU 2016-13, Financial Instruments- Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) as amended, ("ASU 326"), including in February 2020, the FASB issued ASU 2020-02, which provides guidance regarding methodologies, documentation, and internal controls related to expected credit losses. The pronouncement eliminates the incurred credit loss impairment methodology and replaces it with an expected credit loss concept based on historical experience, current conditions, and reasonable and supportable forecasts. Early adoption is permitted. Topic 326 requires a modified retrospective approach by recording a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. We do not expect ASU 326 to have a material impact on our financial statements and related disclosures. Income taxes - In December 2019, FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (Topic 740) ("ASU 2019-12"), wherein the accounting for income taxes is simplified by eliminating certain exceptions and implementing additional requirements, which result in a more consistent application of ASC 740 Income Taxes. ASU 2019-12 is effective as for public business entities, for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. We anticipate that we will no longer be an emerging growth company beginning on December 31, 2020, and expect to adopt this guidance on a prospective basis on January 1, 2021. We do not expect ASU 2019-12 to have a material impact on our financial statements and related disclosures. Cessation of LIBOR - In March 2020, FASB issued ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting ("ASU 2020-04"), which provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. The amendments in ASU 2020-04 are effective for all entities as of March 12, 2020 through December 31, 2022. An entity may elect to apply the amendments for contract modifications as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. We are currently evaluating the impact of the adoption of ASU 2020-04 on our financial statements. Debt with Conversion Options - In August 2020, FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) ("ASU 2020-06"), which simplifies the accounting for convertible instruments. ASU 2020-06 removes certain accounting models that separate the embedded conversion features from the host contract for convertible instruments, requiring bifurcation only if the convertible debt feature qualifies as a derivative under ASC 815 or for convertible debt issued at a substantial premium. ASU 2020-06 removes certain settlement conditions required for equity contracts to qualify for the derivative scope exception, permitting more contracts to qualify for it. In addition, ASU 2020-06 eliminates the treasury stock method to calculate diluted earnings per share for convertible instruments and requires the use of the if-converted method. ASU 2020-06 is effective for annual reporting periods beginning after December 15, 2021, including interim reporting periods within those annual periods, with early adoption permitted no earlier than the fiscal year beginning after December 15, 2020. We are currently evaluating the impact of the adoption of ASU 2020-06 on our consolidated financial statements. We do not expect any other new accounting standards to have a material impact on our financial position, results of operations or cash flows when they become effective.

Nature of Business, Liquidity, Basis of Presentation and Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

We have prepared the unaudited condensed consolidated financial statements included herein pursuant to the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"), and as permitted by those rules, the condensed consolidated financial statements do not include all disclosures required by generally accepted accounting principles as applied in the United States (“U.S. GAAP”). However, we believe that the disclosures herein are adequate to ensure the information presented is not misleading. The condensed consolidated balance sheets as of September 30, 2020 and December 31, 2019 (the latter has been derived from the audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019), and the condensed consolidated statements of operations, of comprehensive loss, of redeemable noncontrolling interest, total stockholders' deficit and noncontrolling interest, and of cash flows for the periods ended September 30, 2020 and 2019, and related notes, should be read in conjunction with the audited financial statements and the notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, as filed with the SEC on March 31, 2020.

We believe that all necessary adjustments, which consisted only of normal recurring items, have been included in the accompanying financial statements to fairly state the results of the interim periods. The results of operations for the interim periods presented are not necessarily indicative of the operating results to be expected for any subsequent interim period or for our fiscal year ending December 31, 2020.

Principles of Consolidation

These condensed consolidated financial statements reflect our accounts and operations and those of our subsidiaries in which we have a controlling financial interest. We use a qualitative approach in assessing the consolidation requirement for each of our variable interest entities ("VIEs"), which we refer to as a tax equity partnership (each such VIE, also referred to as our power purchase agreement entities ("PPA Entities")). This approach focuses on determining whether we have the power to direct those activities of the PPA Entities that most significantly affect their economic performance and whether we have the obligation to absorb losses, or the right to receive benefits, that could potentially be significant to the PPA Entities. For all periods presented, we have determined that we are the primary beneficiary in all of our operational PPA Entities, as discussed in Note 13, Power Purchase Agreement Programs. We evaluate our relationships with the PPA Entities on an ongoing basis to ensure that we continue to be the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation.

Use of Estimates

The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and the accompanying notes. The most significant estimates include the determination of the stand-alone selling price, including material rights estimates, inventory valuation, specifically excess and obsolescence provisions for obsolete or unsellable inventory and, in relation to property, plant and equipment (specifically Energy Servers), assumptions relating to economic useful lives and impairment assessments.

Other accounting estimates include variable consideration relating to product performance guaranties, assumptions to compute the fair value of debt financings, lease and non-lease components and related financing obligations such as incremental borrowing rates, estimated output, efficiency and residual value of the Energy Servers, warranty, product performance guaranties and extended maintenance, derivative valuations, estimates for recapture of U.S. Treasury grants and similar grants, estimates relating to contractual indemnities provisions, estimates for income taxes and deferred tax asset valuation allowances, and stock-based compensation costs. The full extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations and financial condition, including sales, expenses, our allowance for doubtful accounts, stock-based compensation, the carrying value of our long-lived assets, inventory, financial assets, and valuation allowances for tax assets, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning the COVID-19 pandemic and the actions taken to contain it or treat it, as well as the economic impact on local,

regional, national and international customers, suppliers and markets. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods as new information becomes available. Actual results could differ materially from these estimates under different assumptions and conditions.

Recent Accounting Pronouncements

Other than the adoption of the accounting guidance mentioned below, there have been no other significant changes in our reported financial position or results of operations and cash flows resulting from the adoption of new accounting pronouncements.

Accounting Guidance Implemented in 2020

Fair Value Measurement - In August 2018, the Financial Accounting Standards Board ("FASB") issued ASU 2018-13, Fair Value Measurement Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement ("ASU 2018-13"). ASU 2018-13 has eliminated, amended and added disclosure requirements for fair value measurements. Entities will no longer be required to disclose the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy, the policy of timing of transfers between levels of the fair value hierarchy and the valuation processes for Level 3 fair value measurements. Companies will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 was effective for annual and interim periods beginning after December 15, 2019. Early adoption was permitted. We adopted ASU 2018-13 as of January 1, 2020 and the adoption did not have a material effect on our financial statements and related disclosures.

Stock Compensation - In June 2018, FASB issued ASU 2018-07, Compensation - Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"), which aligns the accounting for share-based payment awards issued to employees and nonemployees. Measurement of equity-classified nonemployee awards will now be valued on the grant date and will no longer be remeasured through the performance completion date. ASU 2018-07 also changes the accounting for nonemployee awards with performance conditions to recognize compensation cost when achievement of the

performance condition is probable, rather than upon achievement of the performance condition, as well as eliminating the requirement to reassess the equity or liability classification for nonemployee awards upon vesting, except for certain award types. ASU 2018-07 was effective for us for interim and annual reporting periods beginning after December 15, 2019. Early adoption was permitted. We adopted ASU 2018-07 using a modified retrospective approach on January 1, 2020 and the adoption of ASU 2018-07 did not have a material effect on our financial statements and related disclosures.

Accounting Guidance Not Yet Adopted

We will no longer be an emerging growth company as of December 31, 2020, after which we will not be able to take advantage of the reduced disclosure requirements applicable to emerging growth companies. As a result, we expect to adopt the guidance below regarding Leases and Financial Instruments on a modified retrospective basis on December 31, 2020 and to reflect the adoption as of January 1, 2020 in our annual results for the period ended December 31, 2020.

Leases - In February 2016, FASB issued ASU 2016-02, Leases (Topic 842), as amended (“ASC 842”), which provides new authoritative guidance on lease accounting. Among its provisions, the standard changes the definition of a lease, requires lessees to recognize right-of-use ("ROU") assets and lease liabilities on the balance sheet for operating leases and also requires additional qualitative and quantitative disclosures about lease arrangements. All leases in scope will be classified as either operating or financing. Operating and financing leases will require the recognition of an asset and liability to be measured at the present value of the lease payments. ASC 842 also makes a distinction between operating and financing leases for purposes of reporting expenses on the income statement. We are the lessee under various agreements for facilities and equipment that are currently accounted for as operating leases and expect to continue to enter into new such leases.

Additionally, we expect to continue to enter into Managed Services related financing leases in the future and be the lessor of Energy Servers that are subject to power purchase agreements ("PPAs") with customers under our Managed Services Program and our PPA Program that are currently accounted for as leases. ASC 842 provides a number of optional practical expedients in transition. We will elect the package of practical expedients, which permits us to (1) not reassess whether existing contracts contain leases, (2) carryforward the existing lease classification, and (3) not reassess initial direct costs associated with existing leases.

While we continue to evaluate the effect of adopting ASC 842, we expect that these new standards will not have a material impact to our financial position. We expect to recognize ROU assets and lease liabilities on the consolidated balance sheets with corresponding ROU assets in the range of $24 million to $30 million and lease liabilities in the range of $36 million to $44 million based on the present value of the remaining minimum rental payments under current leasing standards for existing operating leases. While we do not expect that the adoption of ASC 842 will have a material effect on operating income (loss) and net cash flows, it will however impact the classification between cash flows from operations and cash flows from financing activities on the consolidated statements of cash flows.

Financial Instruments - In June 2016, FASB issued ASU 2016-13, Financial Instruments- Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) as amended, ("ASU 326"), including in February 2020, the FASB issued ASU 2020-02, which provides guidance regarding methodologies, documentation, and internal controls related to expected credit losses. The pronouncement eliminates the incurred credit loss impairment methodology and replaces it with an expected credit loss concept based on historical experience, current conditions, and reasonable and supportable forecasts. Early adoption is permitted. Topic 326 requires a modified retrospective approach by recording a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. We do not expect ASU 326 to have a material impact on our financial statements and related disclosures.

Income taxes - In December 2019, FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (Topic 740) ("ASU 2019-12"), wherein the accounting for income taxes is simplified by eliminating certain exceptions and implementing additional requirements, which result in a more consistent application of ASC 740 Income Taxes. ASU 2019-12 is effective as for public business entities, for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. We anticipate that we will no longer be an emerging growth company beginning on December 31, 2020, and expect to adopt this guidance on a prospective basis on January 1, 2021. We do not expect ASU 2019-12 to have a material impact on our financial statements and related disclosures.

Cessation of LIBOR - In March 2020, FASB issued ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting ("ASU 2020-04"), which provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. The amendments in ASU 2020-04 are effective for all entities as of March 12, 2020 through December 31, 2022. An entity may elect to apply the

amendments for contract modifications as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. We are currently evaluating the impact of the adoption of ASU 2020-04 on our financial statements.

Debt with Conversion Options - In August 2020, FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) ("ASU 2020-06"), which simplifies the accounting for convertible instruments. ASU 2020-06 removes certain accounting models that separate the embedded conversion features from the host contract for convertible instruments, requiring bifurcation only if the convertible debt feature qualifies as a derivative under ASC 815 or for convertible debt issued at a substantial premium. ASU 2020-06 removes certain settlement conditions required for equity contracts to qualify for the derivative scope exception, permitting more contracts to qualify for it. In addition, ASU 2020-06 eliminates the treasury stock method to calculate diluted earnings per share for convertible instruments and requires the use of the if-converted method. ASU 2020-06 is effective for annual reporting periods beginning after December 15, 2021, including interim reporting periods within those annual periods, with early adoption permitted no earlier than the fiscal year beginning after December 15, 2020. We are currently evaluating the impact of the adoption of ASU 2020-06 on our consolidated financial statements.

We do not expect any other new accounting standards to have a material impact on our financial position, results of operations or cash flows when they become effective.