REVENUE FROM CONTRACTS WITH CUSTOMERS

Disaggregation of Revenue

The following tables represent a disaggregation of revenue from contracts with customers for the fiscal year 2018, 2017 and 2016 along with the reportable segment for each category:



	Fiscal Year
(In thousands)	SunPower Technologies						SunPower Energy Services						Total Revenue
Category	2018		2017		2016		2018		2017		2016		2018		2017		2016
Module and component sales	$	532,590	$	408,303	$	313,652	$	477,652	$	428,799	$	476,483	$	1,010,242	$	837,102	$	790,135
Solar power systems sales and EPC services	147,756		470,851		1,238,494		213,345		211,850		207,813		361,101		682,701		1,446,307
Operations and maintenance	—		—		—		49,089		43,643		36,208		49,089		43,643		36,208
Leasing¹	125		4,687		1,491		305,528		225,914		278,496		305,653		230,601		279,987
Revenue	$	680,471	$	883,841	$	1,553,637	$	1,045,614	$	910,206	$	999,000	$	1,726,085	$	1,794,047	$	2,552,637

¹Leasing revenue is accounted for in accordance with the lease accounting guidance.

We recognize revenue for sales of modules and components at the point that control transfers to the customer, which typically occurs upon shipment or delivery to the customer, depending on the terms of the contract. For EPC revenue and solar power systems sales, we commence recognizing revenue when control of the underlying system transfers to the customer and continue recognizing revenue over time as work is performed based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligations.

Judgment is required to evaluate assumptions including the amount of net contract revenues and the total estimated costs to determine our progress towards contract completion and to calculate the corresponding amount of revenue to recognize. If estimated total costs on any contract are greater than the net contract revenues, we recognize the entire estimated loss in the period the loss becomes known. For contracts with post-installation systems monitoring and maintenance, we recognize revenue related to systems monitoring and maintenance over the non-cancellable contract term on a straight-line basis.

Changes in estimates for sales of systems and EPC services occur for a variety of reasons, including but not limited to (i) construction plan accelerations or delays, (ii) product cost forecast changes, (iii) change orders, or (iv) changes in other information used to estimate costs. Changes in estimates may have a material effect on our Consolidated Statements of Operations. The table below outlines the impact on revenue of net changes in estimated transaction prices and input costs for systems related sales contracts (both increases and decreases) for the years ended December 30, 2018 and December 31, 2017 as well as the number of projects that comprise such changes. For purposes of the following table, only projects with changes in estimates that have an impact on revenue and or cost of at least $1.0 million during the periods were presented. Also included in the table is the net change in estimate as a percentage of the aggregate revenue for such projects.



	Fiscal Year Ended
(In thousands, except number of projects)	December 30, 2018			December 31, 2017			January 1, 2017
Increase (decrease) in revenue from net changes in transaction prices	$	—		$	—		$	(743	)
Increase (decrease) in revenue from net changes in input cost estimates	(1,045		)	—			5,768
Net increase (decrease) in revenue from net changes in estimates	$	(1,045	)	$	—		$	5,025

Number of projects	1			—			6

Net change in estimate as a percentage of aggregate revenue for associated projects	—		%	—		%	—		%

For the years ended December 30, 2018 and December 31, 2017, there were no material adjustments to revenue as a result of changes in transaction prices or input cost estimates. For the year ended January 1, 2017, revenue increased by $5.0 million from net changes in transaction prices and input cost estimates.

Contract Assets and Liabilities

Contract assets consist of (i) retainage which represents the earned, but unbilled, portion of a construction and development project for which payment is deferred by the customer until certain contractual milestones are met; and (ii) unbilled receivables which represent revenue that has been recognized in advance of billing the customer, which is common for long-term construction contracts. Contract liabilities consist of deferred revenue and customer advances, which represent consideration received from a customer prior to transferring control of goods or services to the customer under the terms of a sales contract. Contract liabilities exclude deferred revenue related to our residential lease program which are accounted for under the lease accounting guidance. Refer to "Note 6. Balance Sheet Components" for further details.

During the year ended December 30, 2018, the increase in contract assets of $43.5 million was primarily driven by unbilled receivables for commercial projects where certain milestones had not yet been reached, but the criteria to recognize revenue had been met. During the year ended December 30, 2018, the decrease in contract liabilities of $31.5 million was primarily due to the attainment of milestones billings for a variety of projects. During the year ended December 30, 2018, we recognized revenue of $94.4 million that was included in contract liabilities as of December 31, 2017. During the year ended December 31, 2017, we recognized revenue of $58.7 million that was included in contract liabilities as of January 1, 2017.

The following table represents our remaining performance obligations as of December 30, 2018 for our sales of solar power systems, including projects under sales contracts subject to conditions precedent, and EPC agreements for developed projects that we are constructing or expect to construct. We expect to recognize $62.3 million of revenue for such contracts upon transfer of control of the projects.



Project	Revenue Category	EPC Contract/Partner Developed Project	Expected Year Revenue Recognition Will Be Completed	Percentage of Revenue Recognized
Joint Base Anacostia Bolling (JBAB)	Solar power systems sales and EPC services	Constellation	2019	98.9%
Miyagi Osato Solar Park	Solar power systems sales and EPC services	SB Energy and TOTAL Solar	2019	85.0%
Various Distribution Generation Projects¹	Solar power systems sales and EPC services	Various	2020	87.4%

¹Denotes average percentage of revenue recognized.

As of December 30, 2018, we entered into contracts with customers for the future sale of modules and components for an aggregate transaction price of $466.6 million, the substantial majority of which we expect to recognize as revenue through 2019. As of December 30, 2018, we had entered into O&M contracts of utility-scale PV solar power systems. We expect to recognize $10.6 million of revenue during the non-cancellable term of these O&M contracts over an average period of three months.