Características de diseño

The following table sets forth cash and cash equivalents, as well as our capitalization, as of December 31, 2013 as follows:

• on an actual basis;

• on a pro forma basis, giving effect to (i) the filing of our amended and restated certificate of incorporation, (ii) the automatic conversion of all outstanding shares of our convertible preferred stock into an aggregate of 19,246,714 shares of common stock and (iii) the automatic conversion of all outstanding debt and settlement of the related derivative instrument of $0.4 million in connection with a subordinated convertible promissory note with a utility partner dated March 8, 2013 into 166,423 shares of common stock, based on an assumed conversion price of $15.84 per share, which is 88% of the midpoint of the estimated offering price range set forth on the cover page of this prospectus, which conversion will occur prior to the completion of this offering, as if such conversion had occurred on December 31, 2013; and

• on a pro forma as adjusted basis, giving effect to the pro forma adjustments set forth above and the sale and issuance by us of 6,100,000 shares of common stock in this offering, based on an assumed initial public offering price of $18.00 per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, and after deducting the estimated underwriting discounts and commissions and estimated offering expenses payable by us. This presentation does not take into consideration the impact of capitalized deferred offering costs. We capitalized $0.8 million of our deferred initial public offering costs as of December 31, 2013 in connection with the preparation of the registration statement of which this prospectus forms a part, of which $0.5 million remained unpaid as of December 31, 2013.

The pro forma as adjusted information set forth in the table below is illustrative only and will be adjusted based on the actual initial public offering price and other final terms of this offering. You should read this table together with our financial statements and related notes, and the sections titled “Selected Financial and Other Data” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” that are included elsewhere in this prospectus.

December 31, 2013 Actual Pro Forma

Pro Forma As Adjusted (In thousands, except share and per

share amounts)

Cash and cash equivalents . . . $ 28,819 $ 28,819 $128,833 Notes payable . . . 2,418 — — Stockholders’ equity (deficit):

Series A, B and C convertible preferred stock, par value $0.000005 per share: 19,428,252 shares authorized, 19,246,714 shares issued and outstanding, actual; no shares authorized, issued and outstanding, pro forma and pro forma

as adjusted . . . 67,693 — — Preferred stock, par value $0.000005 per share: no shares authorized, issued and

outstanding, actual; 25,000,000 shares authorized, no shares issued and

outstanding, pro forma and pro forma as adjusted . . . — — — Common stock, par value $0.000005 per share, 62,000,000 shares authorized,

22,113,125 shares issued and outstanding, actual; 500,000,000 shares authorized, 41,526,262 shares issued and outstanding, pro forma; 500,000,000 shares authorized, 47,626,262 shares issued and outstanding, pro forma as

adjusted . . . — — — Additional paid-in capital . . . 9,407 79,906 179,920 Treasury stock . . . — — — Accumulated deficit . . . (83,243) (83,243) (83,243) Accumulated other comprehensive loss . . . (120) (120) (120) Total stockholders’ equity (deficit) . . . (6,263) (3,457) 96,557

If the underwriters’ option to purchase additional shares from us were exercised in full, pro forma as adjusted cash and cash equivalents, additional paid-in capital, total stockholders’ equity (deficit) and shares issued and outstanding as of December 31, 2013 would be $144.2 million, $195.2 million, $111.9 million and 48,541,262 shares, respectively.

Each $1.00 increase or decrease in the assumed initial public offering price of $18.00 per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, would increase or decrease, as applicable, our cash and cash equivalents, additional paid-in capital, and total stockholders’ equity (deficit) by approximately $5.7 million, assuming that the number of shares offered by us, as set forth on the cover page of this prospectus, remains the same and after deducting the estimated underwriting discounts and commissions payable by us.

The number of shares of our common stock outstanding in the table above excludes the following:

• 7,789,720 shares of common stock issuable upon the exercise of options to purchase common stock that were outstanding as of December 31, 2013, with a weighted-average exercise price of $3.83 per share; • 1,093,326 shares of common stock issuable upon the vesting of restricted stock units that were

outstanding as of December 31, 2013;

• 50,000 shares of common stock issuable upon the exercise of options to purchase common stock that were granted after December 31, 2013 with an exercise price of $18.00 per share;

• 485,950 shares of common stock issuable upon the vesting of restricted stock units that were granted after December 31, 2013; and

• 5,993,902 shares of common stock reserved for future issuance under our stock-based compensation plans, consisting of 993,902 shares reserved for future issuance under our 2007 Stock Plan (1,529,852 shares of common stock reserved for future issuance under our 2007 Stock Plan as of December 31, 2013 minus 535,950 shares granted since December 31, 2013), which shares will be added to the shares to be reserved under our 2014 Stock Incentive Plan, and 5,000,000 shares of common stock reserved for future issuance under our 2014 Stock Incentive Plan, which will become effective in connection with this offering, and shares that become available pursuant to provisions thereof that automatically increase the share reserves under the 2014 Stock Incentive Plan each year.

DILUTION

If you invest in our common stock in this offering, your ownership interest will be diluted to the extent of the difference between the initial public offering price per share of our common stock and the pro forma as adjusted net tangible book value per share of our common stock immediately after this offering. Net tangible book value dilution per share to new investors represents the difference between the amount per share paid by purchasers of shares of common stock in this offering and the pro forma as adjusted net tangible book value per share of common stock immediately after completion of this offering.

Net tangible book value per share is determined by dividing our total tangible assets less our total liabilities by the number of shares of common stock outstanding. Our historical net tangible book value (deficit) as of December 31, 2013 was $(12.6) million, or $(0.57) per share. Our pro forma net tangible book value (deficit) as of December 31, 2013 was $(12.6) million, or $(0.31) per share, based on the total number of shares of our common stock outstanding as of December 31, 2013, after giving effect to the automatic conversion of all outstanding shares of our convertible preferred stock as of December 31, 2013 into an aggregate of 19,246,714 shares of common stock, which will occur immediately prior to the completion of this offering.

After giving effect to the sale by us of 6,100,000 shares of common stock in this offering at the assumed initial public offering price of $18.00 per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, and after deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us, our pro forma as adjusted net tangible book value as of December 31, 2013 would have been $87.4 million, or $1.84 per share. This represents an immediate increase in pro forma net tangible book value of $2.15 per share to our existing stockholders and immediate dilution of $16.16 per share to investors purchasing shares of common stock in this offering at the assumed initial public offering price. The following table illustrates this dilution:

Assumed initial public offering price per share . . . $18.00 Pro forma net tangible book value (deficit) per share as of December 31, 2013 . . . $(0.31)

Increase in pro forma net tangible book value (deficit) per share attributable to new

investors in this offering . . . 2.15 Pro forma as adjusted net tangible book value per share immediately after this

offering . . . 1.84 Dilution per share to new investors in this offering . . . $16.16 Each $1.00 increase or decrease in the assumed initial public offering price of $18.00 per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, would increase or decrease, as applicable, our pro forma as adjusted net tangible book value per share to new investors by $0.12, and would increase or decrease, as applicable, dilution per share to new investors in this offering by $0.88, assuming that the number of shares offered by us, as set forth on the cover page of this prospectus, remains the same and after deducting estimated underwriting discounts and commissions payable by us. In addition, to the extent any outstanding options to purchase common stock are exercised, new investors would experience further dilution. If the underwriters exercise their option to purchase additional shares from us in full, the pro forma as adjusted net tangible book value per share of our common stock immediately after this offering would be $2.12 per share, and the dilution in pro forma net tangible book value per share to new investors in this offering would be $15.88 per share.

The following table presents, on a pro forma as adjusted basis as of December 31, 2013, after giving effect to the conversion of all outstanding shares of convertible preferred stock into common stock immediately prior to the completion of this offering, the differences between the existing stockholders and the new investors purchasing shares of our common stock in this offering with respect to the number of shares purchased from us,

the total consideration paid or to be paid to us, which includes net proceeds received from the issuance of common stock and convertible preferred stock, cash received from the exercise of stock options, and the average price per share paid or to be paid to us at an assumed offering price of $18.00 per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, before deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us:

Shares Purchased Total Consideration Average_Price Per Share

Number Percent Amount Percent

Existing stockholders . . . 41,359,839 87.1% $ 71,288,961 39.4% $ 1.72 New investors . . . 6,100,000 12.9 109,800,000 60.6 18.00 Totals . . . 47,459,839 100.0% $181,088,961 100.0% $ 3.82 Each $1.00 increase or decrease in the assumed initial public offering price of $18.00 per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, would increase or decrease, as applicable, the total consideration paid by new investors and total consideration paid by all stockholders by approximately $6.1 million, assuming that the number of shares offered by us, as set forth on the cover page of this prospectus, remains the same and after deducting estimated underwriting discounts and commissions payable by us. In addition, to the extent any outstanding options to purchase common stock are exercised, new investors will experience further dilution.

Except as otherwise indicated, the above discussion and tables assume no exercise of the underwriters’ option to purchase additional shares. If the underwriters exercise their option to purchase additional shares in full from us, our existing stockholders would own 85.5% and our new investors would own 14.5% of the total number of shares of our common stock outstanding upon the completion of this offering.

The number of shares of our common stock to be outstanding after this offering is based on the number of shares of our common stock outstanding as of December 31, 2013 and excludes:

• 7,789,720 shares of common stock issuable upon the exercise of options to purchase common stock that were outstanding as of December 31, 2013, with a weighted-average exercise price of $3.83 per share; • 1,093,326 shares of common stock issuable upon the vesting of restricted stock units that were

outstanding as of December 31, 2013;

• 50,000 shares of common stock issuable upon the exercise of options to purchase common stock that were granted after December 31, 2013 with an exercise price of $18.00 per share;

• 485,950 shares of common stock issuable upon the vesting of restricted stock units that were granted after December 31, 2013;

• 166,423 shares of common stock issuable upon the conversion of the subordinated convertible promissory note with a utility partner dated March 8, 2013, based on an assumed conversion price of $15.84 per share, which is 88% of the midpoint of the estimated offering price range set forth on the cover page of this prospectus; and

• 5,993,902 shares of common stock reserved for future issuance under our stock-based compensation plans, consisting of 993,902 shares reserved for future issuance under our 2007 Stock Plan (1,529,852 shares of common stock reserved for future issuance under our 2007 Stock Plan as of December 31, 2013 minus 535,950 shares granted since December 31, 2013), which shares will be added to the shares to be reserved under our 2014 Stock Incentive Plan, and 5,000,000 shares of common stock reserved for future issuance under our 2014 Stock Incentive Plan, which will become effective in connection with this offering, and shares that become available pursuant to provisions thereof that automatically increase the share reserves under the 2014 Stock Incentive Plan each year.