Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of stock option activity

The following table summarizes the activity for all stock options under all of the Company’s equity incentive plans for the six months ended June 30, 2018 (shares and aggregate intrinsic value in thousands):

	Number of Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value
Outstanding at December 31, 2017	16,268		$	5.70	7.41	$	14,832
Granted	1,436		8.33
Exercised	(1,529	)	5.25
Cancelled / forfeited	(480	)	4.33
Outstanding at June 30, 2018	15,695		$	5.94	7.27	$	114
Options vested and exercisable at June 30, 2018	8,624		$	5.52	6.18	$	66,074

Summary of activity for all restricted stock units (RSUs)

The following table summarizes the activity for all restricted stock units (“RSUs”) under all of the Company’s equity incentive plans for the six months ended June 30, 2018 (shares in thousands):

	Number of Awards		Weighted Average Grant Date Fair Value
Unvested balance at December 31, 2017	5,330		$	5.82
Granted	1,778		8.12
Issued	(1,206	)	6.57
Cancelled / forfeited	(820	)	6.72
Unvested balance at June 30, 2018	5,082		$	6.49

Summary of stock-based compensation expense

The Company recognized stock-based compensation expense, including ESPP expenses, in the consolidated statements of operations as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Cost of customer agreements and incentives	$	667	$	1,110	$	1,279	$	1,861
Cost of solar energy systems and product sales	186		156		357		270
Sales and marketing	834		807		4,984		2,724
Research and development	311		186		605		335
General and administration	3,549		3,256		9,017		6,199
Total	$	5,547	$	5,515	$	16,242	$	11,389