Stockholder’s Equity	3 Months Ended
Mar. 31, 2017
Stockholder’s Equity	9. Equity Unit-based compensation In 2016 and 2017, there were no additional membership units issued by Solaris LLC under the Plan. At March 31, 2017 and December 31, 2016, there were 12,938 option units outstanding and 47,062 option units available for grant. On May 4, 2017, 366 options were forfeited. The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model. Expected volatility is based on implied volatilities from historical trading of publicly traded companies which are in the same industry sector. The simplified method is used to derive an expected term. The expected term represents an estimate of the time options are expected to remain outstanding. The risk-free rate for periods within the contractual life of the option is based on the U.S. treasury yield curve in effect at the time of grant. Compensation cost, as measured at the grant date fair value of the award, is recognized as an expense over the employee’s requisite service period for service based awards (generally the vesting period of the award of four years). For the three months ended March 31, 2017 and 2016, the Company recognized $32 and $36 of stock-based compensation expense attributable to vested awards, respectively. At March 31, 2017 and December 31, 2016, there was $291 and $323 in unrecognized compensation costs. Effective May 17, 2017, both the Board of Directors of Solaris (the “Board”) and the holder of all Solaris’ then-outstanding equity interests adopted the LTIP for the benefit of employees, directors and consultants of the Company and its affiliates. The LTIP provides for the grant of all or any of the following types of equity-based awards: (1) incentive stock options qualified as such under U.S. federal income tax laws; (2) stock options that do not qualify as incentive stock options; (3) stock appreciation rights; (4) restricted stock awards; (5) restricted stock units; (6) bonus stock; (7) performance awards; (8) dividend equivalents; (9) other stock-based awards; (10) cash awards; and (11) substitute awards. Subject to adjustment in accordance with the terms of the LTIP, 5,118,080 shares of Solaris’ Class A Common Stock have been reserved for issuance pursuant to awards under the LTIP. Class A Common Stock withheld to satisfy exercise prices or tax withholding obligations will be available for delivery pursuant to other awards. The LTIP will be administered by the Board, the Compensation Committee of the Board or an alternative committee appointed by the Board. In connection with the Offering, the options granted under the Plan were exchanged for options under the LTIP. A total of 591,261 options to purchase Class A Common Stock of the Company were issued to employees, directors and consultants at an exercise price of $2.87 per share. Twenty-five percent (25%) of the options were considered vested upon the grant. An additional 25% of the options will be vested on July 24, 2017. The remaining options will vest on November 13, 2017. The vesting terms from the options under the LTIP are accelerated from the previous vesting terms under the Plan. In addition, in connection with the Offering, a total of 648,676 shares of restricted stock were granted to certain employees, directors and consultants under the LTIP. 203,222 shares of the restricted stock were issued with a one-year vesting period and 445,454 shares of the restricted stock were issued with a three-year vesting period. Notes receivable from unit-holders Solaris LLC’s Limited Liability Company Agreement authorized Solaris LLC to issue membership units at a value of $100 per unit to Solaris LLC’s employees in exchange for a promissory note. The promissory notes are partial recourse, accrue interest at 6% per annum and mature through various dates during 2022. Principal and accrued interest are due and payable upon the earlier of employee termination or the maturity date of the note. As of March 31, 2017, there were 19,508 units issued to non-executive officer employees and consultants under promissory notes. In 2016 and 2017, there were no additional units issued. In March 2017, certain employees paid off their applicable promissory notes of $2.7 million principal and approximately $315 of accrued interest in cash for previously assigned 27,368 units. As of March 31, 2017 and December 31, 2016, the outstanding principal for the notes totaled $1,951 and $4,688 and accrued interest for the notes totaled $177 and $457, respectively. These notes are recorded in members’ equity as the notes were originally received in exchange for the issuance of membership units and are netted against the value of the respective units issued. On May 22, 2017, June 2, 2017 and June 5, 2017, certain employees paid off portions of their applicable promissory notes totaling $1,259 related to previously assigned 19,508 units.
Solaris
Stockholder’s Equity	3. Stockholder’s Equity As of March 31, 2017, Solaris has authorized share capital of 1,000 common shares with $0.01 par value per share, 1,000 shares of which were issued and acquired by an affiliate for consideration of $10 note receivable from that affiliate. Each share has one voting right.

9. Equity

Unit-based compensation

In 2016 and 2017, there were no additional membership units issued by Solaris LLC under the Plan. At March 31, 2017 and December 31, 2016, there were 12,938 option units outstanding and 47,062 option units available for grant. On May 4, 2017, 366 options were forfeited.

The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model. Expected volatility is based on implied volatilities from historical trading of publicly traded companies which are in the same industry sector. The simplified method is used to derive an expected term. The expected term represents an estimate of the time options are expected to remain outstanding. The risk-free rate for periods within the contractual life of the option is based on the U.S. treasury yield curve in effect at the time of grant. Compensation cost, as measured at the grant date fair value of the award, is recognized as an expense over the employee’s requisite service period for service based awards (generally the vesting period of the award of four years). For the three months ended March 31, 2017 and 2016, the Company recognized $32 and $36 of stock-based compensation expense attributable to vested awards, respectively. At March 31, 2017 and December 31, 2016, there was $291 and $323 in unrecognized compensation costs.

Effective May 17, 2017, both the Board of Directors of Solaris (the “Board”) and the holder of all Solaris’ then-outstanding equity interests adopted the LTIP for the benefit of employees, directors and consultants of the Company and its affiliates. The LTIP provides for the grant of all or any of the following types of equity-based awards: (1) incentive stock options qualified as such under U.S. federal income tax laws; (2) stock options that do not qualify as incentive stock options; (3) stock appreciation rights; (4) restricted stock awards; (5) restricted stock units; (6) bonus stock; (7) performance awards; (8) dividend equivalents; (9) other stock-based awards; (10) cash awards; and (11) substitute awards. Subject to adjustment in accordance with the terms of the LTIP, 5,118,080 shares of Solaris’ Class A Common Stock have been reserved for issuance pursuant to awards under the LTIP. Class A Common Stock withheld to satisfy exercise prices or tax withholding obligations will be available for delivery pursuant to other awards. The LTIP will be administered by the Board, the Compensation Committee of the Board or an alternative committee appointed by the Board.

In connection with the Offering, the options granted under the Plan were exchanged for options under the LTIP. A total of 591,261 options to purchase Class A Common Stock of the Company were issued to employees, directors and consultants at an exercise price of $2.87 per share. Twenty-five percent (25%) of the options were considered vested upon the grant. An additional 25% of the options will be vested on July 24, 2017. The remaining options will vest on November 13, 2017. The vesting terms from the options under the LTIP are accelerated from the previous vesting terms under the Plan.

In addition, in connection with the Offering, a total of 648,676 shares of restricted stock were granted to certain employees, directors and consultants under the LTIP. 203,222 shares of the restricted stock were issued with a one-year vesting period and 445,454 shares of the restricted stock were issued with a three-year vesting period.

Notes receivable from unit-holders

Solaris LLC’s Limited Liability Company Agreement authorized Solaris LLC to issue membership units at a value of $100 per unit to Solaris LLC’s employees in exchange for a promissory note. The promissory notes are partial recourse, accrue interest at 6% per annum and mature through various dates during 2022. Principal and accrued interest are due and payable upon the earlier of employee termination or the maturity date of the note.

As of March 31, 2017, there were 19,508 units issued to non-executive officer employees and consultants under promissory notes. In 2016 and 2017, there were no additional units issued. In March 2017, certain employees paid off their applicable promissory notes of $2.7 million principal and approximately $315 of accrued interest in cash for previously assigned 27,368 units.

As of March 31, 2017 and December 31, 2016, the outstanding principal for the notes totaled $1,951 and $4,688 and accrued interest for the notes totaled $177 and $457, respectively. These notes are recorded in members’ equity as the notes were originally received in exchange for the issuance of membership units and are netted against the value of the respective units issued. On May 22, 2017, June 2, 2017 and June 5, 2017, certain employees paid off portions of their applicable promissory notes totaling $1,259 related to previously assigned 19,508 units.