Revenue Recognition

3 Months Ended

Mar. 31, 2022

Revenue from Contract with Customer [Abstract]

Revenue Recognition

Revenue Recognition

Contract Balances

The following table provides information about accounts receivables, contract assets, customer deposits and deferred revenue from contracts with customers (in thousands):

	March 31,		December 31,
	2022		2021
Accounts receivable	$	110,842	$	87,788
Contract assets	13,533		25,201
Customer deposits	71,013		64,809
Deferred revenue	103,489		115,476

Contract assets relate to contracts for which revenue is recognized upon transfer of control of performance obligations, however billing milestones have not been reached. Customer deposits and deferred revenue are payments received from customers or invoiced amounts prior to transfer of controls of performance obligations. Customer deposits, except for those related to the transaction with SK ecoplant, are refundable fees until certain milestones are met.

Contract Assets

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	25,201	$	3,327
Transferred to accounts receivable from contract assets recognized at the beginning of the period	(14,576)		(4,277)
Revenue recognized and not billed as of the end of the period	2,908		5,958
Ending balance	$	13,533	$	5,008

Deferred Revenue

Deferred revenue activity, including deferred incentive revenue activity, during the three months ended March 31, 2022 and 2021 consisted of the following (in thousands):

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	115,476	$	135,578
Additions	166,676		156,586
Revenue recognized	(178,663)		(171,521)
Ending balance	$	103,489	$	120,643

Deferred revenue is equivalent to the total transaction price allocated to the performance obligations that are unsatisfied, or partially unsatisfied, as of the end of the period. The significant component of deferred revenue at the end of the period consists of performance obligations relating to the provision of maintenance services under current contracts and future renewal periods. These obligations provide customers with material rights over a period that we estimate will be largely commensurate with the period of their expected use of the associated Energy Server. As a result, we expect to recognize these amounts as revenue over a period of up to 21 years, predominantly on a relative standalone selling price basis that reflects the cost of providing these services. Deferred revenue also includes performance obligations relating to product acceptance and installation. A significant amount of this deferred revenue is reflected as additions and revenue recognized in the same period and we expect to recognize substantially all amounts within a year.

We do not disclose the value of the unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which we recognize revenue at the amount to which we have the right to invoice for services performed.

Disaggregated Revenue

We disaggregate revenue from contracts with customers into four revenue categories: product, installation, services and electricity (in thousands):

	Three Months Ended March 31,
	2022		2021
Revenue from contracts with customers:
Product revenue	$	133,547	$	137,930
Installation revenue	13,553		2,659
Services revenue	35,239		36,417
Electricity revenue	2,682		595
Total revenue from contract with customers	185,021		177,601
Revenue from contracts accounted for as leases:
Electricity revenue	16,018		16,406
Total revenue	$	201,039	$	194,007