Item 1.01 Entry into a Material Definitive Agreement. Securities Purchase Agreement On March 16, 2026, Solaris Energy Infrastructure, Inc., a Delaware corporation (the “ Company”), entered into a Securities Purchase Agreement (the “ Purchase Agreement”) with Solaris Energy Infrastructure, LLC, a Delaware limited liability company and operating subsidiary of the Company (“ OpCo”), Project G Buyer, LLC, a Texas limited liability company and then a wholly owned subsidiary of the Company (the “ Buyer”), Focus Genco Cayman Ltd., an exempted company with limited liability incorporated organized under the laws of the Cayman Islands (“ Genco”), the holders of shares of Genco (each, a “ Seller” and, collectively, the “Sellers”) and Alan Zelazo, solely in his capacity as the Sellers representative under the Purchase Agreement (the “ Sellers Representative”).

Item 1.02 Termination of a Material Definitive Agreement. Termination of ABL On March 16, 2026, substantially concurrently with the closing of the Term Loan Agreement, the ABL Borrowers (as defined below) terminated that certain loan, security and guaranty agreement, dated as of October 2, 2024 (as amended, restated, supplemented or otherwise modified from time to time, the “ LSA”), by and among the Company and certain of its subsidiaries, as borrowers (the “ ABL Borrowers”), Bank of America, N. A., as agent, and the lenders party thereto. For a description of the LSA, please see “ Management’s Discussion and Analysis of Financial Condition and Results of Operations - Liquidity and Capital Resources - Term Loan and Revolving Credit Facility” in the Company’s Annual Report on Form10-Kfor the year ended December 31, 2025.

Item 2.01 Completion of Acquisition or Disposition of Assets. The information set forth in Item 1.01 of this Current Report on Form8-Kis incorporated by reference into this Item 2.01.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-BalanceSheet Arrangement of a Registrant. The information set forth in Item 1.01 of this Current Report on Form8-Kis incorporated by reference into this Item 2.03.

Item 3.02 Unregistered Sales of Equity Securities. The information set forth in Item 1.01 of this Current Report on Form8-Kis incorporated by reference into this Item 3.02. The issuance of the Equity Consideration to the Sellers was completed in reliance upon the exemption from the registration requirements of the Securities Act of 1933, as amended, provided by Section 4(a)(2) thereof as a transaction by an issuer not involving any public offering. The Company relied on this exemption from registration based in part on representations made by the Sellers.

Item 8.01 Other Events. On March 16, 2026, the Company announced the consummation of the transactions contemplated by the Assignment, Assumption, Novation and Amendment Agreement, dated March 13, 2026 (the “ Assumption Agreement”), with Colusa Power Infrastructure Partners, LLC, a Delaware limited liability company (“ Colusa”) and Baker Hughes Energy Services LLC, a Delaware limited liability company (“ Baker Hughes”), pursuant to which Solaris Power assumed all of Colusa’s right, title, interest, duties, obligations and liabilities in, to and under a Contract Agreement (the “ Turbine Purchase Agreement”), by and between Colusa and Baker Hughes. Pursuant to the Assumption Agreement and the Turbine Purchase Agreement, Solaris Power acquired 30 gas turbine generator delivery slots, which are expected to provide approximately 500 megawatts of power generation capacity between early 2027 and 2029.

Item 9.01 Financial Statements and Exhibits. (a) Financial Statements of Business Acquired To be filed by amendment not later than 71 calendar days after the date this Current Report on Form8-Kis required to be filed. (b) Pro Forma Financial Information To be filed by amendment not later than 71 calendar days after the date this Current Report on Form8-Kis required to be filed. (d)  Exhibits. Exhibit Description Number 2.1 Securities Purchase Agreement among the Company, OpCo, Buyer, Sellers, Target and Sellers Representative, dated as of March 16, 2026. 10.1 Term Loan Agreement, dated March 16, 2026. 10.2 Loan and Security Agreement, dated March 16, 2026. ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 104 Cover Page Interactive Data File (formatted as inline XBRL). SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Date: March 20, 2026 SOLARIS ENERGY INFRASTRUCTURE, INC. By: /s/ STEPHAN E. TOMPSETT Name: Stephan E. Tompsett Title: Chief Financial Officer