Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2015

Disclosure Of Compensation Related Costs Sharebased 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, 2015 (shares in thousands):

				Weighted		Weighted
				Average		Average
	Options			Exercise Price		Remaining
	Outstanding			Outstanding		Contractual Life
Outstanding at December 31, 2014		11,408		$	4.42	$	8.2
Granted		2,863			9.17
Exercised		(854	)		2.79
Cancelled / forfeited		(783	)		5.00
Outstanding at June 30, 2015		12,634		$	5.57	$	7.1
Options vested and exercisable at    June 30, 2015		5,414			3.63	$	6.2
Options vested and expected to vest  at    June 30, 2015		10,480			5.31	$	8.1

Estimated Fair Value of Stock Options

The Company estimated the fair value of stock options with the following assumptions:

	Three Months Ended June 30,		Six Months Ended June 30,
	2015	2014	2015	2014
Risk-free interest rate	1.55%-1.95%	1.77%-1.88%	1.55%-1.95%	1.68%-1.90%
Volatility	36.54%-39.63%	46.25%-46.30%	36.54%-39.63%	43.77%-46.68%
Expected term (in years)	5.87-6.23	5.92-6.08	5.87-6.23	5.34-6.08
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Summary of Activity for All RSUs

The following table summarizes the activity for all RSUs under all the Company’s equity inventive plans for the six months ended June 30, 2015 (shares in thousands):

			Weighted
			Average Grant
			Date Fair
	Shares		Value
Unvested balance at December 31, 2014		947	$	9.40
Granted		170		10.81
Vested		—		—
Cancelled / forfeited		—		—
Unvested balance at June 30, 2015		1,117	$	9.61

Summary of Stock-Based Compensation Expense

The Company recognized stock-based compensation expense, including the compensation expense resulting from the sales of common stock by employees and former employees to existing investors, in the consolidated statements of operations as follows (in thousands):

	For the Three Months				For the Six Months
	Ended June 30,				Ended June 30,
	2015		2014		2015		2014
Cost of operating leases and incentives	$	248	$	61	$	297	$	112
Cost of solar energy systems and product sales		35		37		112		67
Sales and marketing		1,209		288		1,636		496
Research and development		64		95		126		139
General and administration		1,645		1,982		4,250		3,496
Total	$	3,201	$	2,463	$	6,421	$	4,310