X0202 SCHEDULE 13G/A 0001193125-18-045614 0001577919 XXXXXXXX LIVE 4 Class A common stock, par value $0.01 per share 05/06/2026 0001697500 Solaris Energy Infrastructure, Inc. 83418M103 9651 Katy Freeway Suite 300 Houston TX 77024 YORKTOWN ENERGY PARTNERS X, L.P. DE 0 5079234 0 5079234 5079234 7.2 PN YORKTOWN X COMPANY LP b DE 0 5079234 0 5079234 5079234 7.2 PN YORKTOWN X ASSOCIATES LLC b DE 0 5079234 0 5079234 5079234 7.2 OO Solaris Energy Infrastructure, Inc. 9651 Katy Freeway, Suite 300, Houston, Texas 77024. This statement is jointly filed by Yorktown Energy Partners X, L.P., a Delaware limited partnership ("Yorktown X"), Yorktown X Company LP, a Delaware limited partnership and the general partner of Yorktown X ("Yorktown X Company"), and Yorktown X Associates LLC, a Delaware limited liability company and the general partner of Yorktown X Company ("Yorktown X Associates", and collectively, with Yorktown X and Yorktown X Company, the "Reporting Persons"). The principal business office address of Yorktown X, Yorktown X Company and Yorktown X Associates is 410 Park Avenue, 20th Floor, New York, New York 10022. Each of Yorktown X, Yorktown X Company and Yorktown X Associates is organized under the laws of the state of Delaware. Y The information required by Item 4(a) is set forth in Row 9 of the cover pages hereto for each Reporting Person and is incorporated herein by reference for each Reporting Person. Beneficial ownership of the Class A common stock, par value $0.01 per share ("Class A Common Stock"), of the Issuer referred to herein is being reported hereunder solely because the reporting person directly owns 5,079,234 shares of Class B common stock of the Issuer ("Class B Common Stock") and 5,079,234 membership interests ("Solaris LLC Units") in Solaris Energy Infrastructure, LLC ("Solaris LLC"), which are exchangeable for shares of Class A Common Stock on a one-for-one basis, pursuant to the Second Amended and Restated Limited Liability Company Agreement of Solaris LLC. Neither the filing of this Schedule 13G nor any of its contents shall be deemed to constitute an admission by any reporting person that it is the beneficial owner of any of the securities referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed. The information required by Item 4(b) is set forth in Row 11 of the cover pages hereto for each Reporting Person and is incorporated herein by reference for each Reporting Person. Based on 65,831,540 shares of Class A Common Stock of the Issuer issued and outstanding as of August 3, 2026 as reported in the Issuer's quarterly report on Form 10-Q for the fiscal quarter ended June 30, 2026, filed with the SEC on August 6, 2026 and 5,079,234 shares of Class A Common Stock issuable upon the exchange of shares of Class B Common Stock together with Solaris LLC Units as described above. The information required by Item 4(c)(i) is set forth in Row 5 of the cover pages hereto for each Reporting Person and is incorporated herein by reference for each Reporting Person. The information required by Item 4(c)(ii) is set forth in Row 6 of the cover pages hereto for each Reporting Person and is incorporated herein by reference for each Reporting Person. These securities are directly held by Yorktown Energy Partners X, L.P., a Delaware limited partnership. Yorktown X Company LP, a Delaware limited partnership, is the sole general partner of Yorktown X and Yorktown X Associates LLC, a Delaware limited liability company, is the sole general partner of Yorktown X Company. As a result, Yorktown X Company and Yorktown X Associates may be deemed to have the power to vote or direct the vote or to dispose or direct the disposition of the shares owned by Yorktown X. Yorktown X Company and Yorktown X Associates disclaim beneficial ownership of the securities owned by Yorktown X in excess of its pecuniary interests therein. The information required by Item 4(c)(iii) is set forth in Row 7 of the cover pages hereto for each Reporting Person and is incorporated herein by reference for each Reporting Person. The information required by Item 4(c)(iv) is set forth in Row 8 of the cover pages hereto for each Reporting Person and is incorporated herein by reference for each Reporting Person. These securities are directly held by Yorktown Energy Partners X, L.P., a Delaware limited partnership. Yorktown X Company LP, a Delaware limited partnership, is the sole general partner of Yorktown X and Yorktown X Associates LLC, a Delaware limited liability company, is the sole general partner of Yorktown X Company. As a result, Yorktown X Company and Yorktown X Associates may be deemed to have the power to vote or direct the vote or to dispose or direct the disposition of the shares owned by Yorktown X. Yorktown X Company and Yorktown X Associates disclaim beneficial ownership of the securities owned by Yorktown X in excess of its pecuniary interests therein. Y Y Y Y Y Y YORKTOWN ENERGY PARTNERS X, L.P. /s/ Robert A. Signorino 08/12/2026 YORKTOWN X COMPANY LP /s/ Robert A. Signorino 08/12/2026 YORKTOWN X ASSOCIATES LLC /s/ Robert A. Signorino 08/12/2026