Item 1.01. Entry Into or Amendment of a Material Definitive Agreement. Convertible Notes Underwriting Agreement On May 1, 2025, Solaris Energy Infrastructure, Inc. (the “ Company”) entered into an underwriting agreement (the “ Convertible Notes Underwriting Agreement”) with Morgan Stanley & Co. LLC, as representative of the several underwriters named in Schedule I thereto, in connection with the issuance and sale of $155,000,000 aggregate principal amount of the Company’s 4.75% Convertible Senior Notes due 2030 (the “ Notes” and the issuance and sale of the Notes, the “ Notes Offering”). Pursuant to the Convertible Notes Underwriting Agreement, the Company granted the underwriters an option to purchase, in addition to the base $135,000,000 and for settlement within a period of 30 days from the date thereof, up to an additional $20,000,000 principal amount of Notes, which was exercised in full on May 1, 2025. The Notes were offered and sold in an offering registered under the Securities Act of 1933, as amended (the “ Securities Act”), pursuant to the Company’s Registration Statement on FormS-3(FileNo. 333-286868), as supplemented by a preliminary prospectus supplement dated April 30, 2025, the pricing term sheet dated May 1, 2025, and a final prospectus supplement dated May 1, 2025.

Item 2.03. Creation of a Direct Financial Obligation or an Off-Balance Sheet Arrangement. The disclosure set forth in Item 1.01 above under the caption “ Convertible Notes - Indenture” is incorporated by reference into this Item 2.03.

Item 9.01. Financial Statements and Exhibits. (d)  Exhibits Exhibit Description No. 1.1 Underwriting Agreement, dated as of May 1, 2025, by and between Solaris Energy Infrastructure, Inc. and Morgan Stanley & Co. LLC, as representative of the underwriters named therein (Notes Offering). 1.2 Underwriting Agreement, dated as of May 1, 2025, by and between Solaris Energy Infrastructure, Inc. and Morgan Stanley & Co. LLC, as representative of the underwriters named therein (Concurrent Delta Offering). 4.1 Indenture, dated May 2, 2025, by and between Solaris Energy Infrastructure, Inc. and U. S. Bank national Association, as Trustee. 4.2 FirstSupplemental Indenture, dated as of May 2, 2025, between Solaris Energy Infrastructure, Inc. and U. S. Bank Trust Company, National Association, as trustee. ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 4.3 Form of 4.75% Convertible Senior Note Due 2030 (included as Exhibit A to Exhibit 4.2). 5.1 Opinion of Vinson & Elkins L. L. P. (Notes Offering). 5.2 Opinion of Vinson & Elkins L. L. P. (Concurrent Delta Offering). 23.1 Consent of Vinson & Elkins L. L. P. (Notes Offering) (included in Exhibit 5.1). 23.2 Consent of Vinson & Elkins L. L. P. (Concurrent Delta Offering) (included in Exhibit 5.2). 104 Cover Page Interactive Data File (embedded within Inline XBRL document). 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. SOLARIS ENERGY INFRASTRUCTURE, INC. By: /s/ Kyle S. Ramachandran Name: Kyle S. Ramachandran Title: President and Chief Financial Officer