Item 1.01. Entry into a Material Definitive Agreement. On February 28, 2025, Tecogen Inc. (“ Company,” “we,” “our, ”us”) entered into a Sales and Marketing Agreement with Vertiv Corporation, an Ohio corporation (“ Vertiv”), a subsidiary of Vertiv Holdings Co., a Delaware corporation (NYSE: VRT), relating to sales and marketing of Tecogen DTx Chillers (“ Tecogen Chillers”) for data center cooling applications (the “ Agreement”). The Agreement is effective March 1, 2025 and has a term of two years. The Agreement provides that Vertiv will establish a budget for marketing activities and use commercially reasonable efforts to sell Tecogen Chillers for cooling applications in data centers. The Agreement also provides the basis for the negotiation of a definitive supply agreement between Vertiv and us, and that the Agreement may be terminated by either party if the parties are unable to enter into a definitive supply agreement. We have agreed to provide Vertiv with reasonable discounts for purchases of significant volumes of Tecogen Chillers, and Vertiv has agreed to use commercially reasonable efforts to assist us in securing favorable terms for engineering components and supplies for manufacturing Tecogen Chillers. Pursuant to the Agreement we have granted Vertiv the exclusive right to market and sell Tecogen Chillers for use in data center cooling applications outside the United States, and the non-exclusive right to market and sell Tecogen Chillers for data center cooling applications within the United States. We have also agreed to grant Vertiv exclusive rights to market and sell Tecogen Chillers for data center cooling applications in the United States if Vertiv achieves and maintains agreed sales levels of Tecogen Chillers. The foregoing description of the Agreement is not complete and is qualified in its entirety by reference to the full text of the Agreement filed as Exhibit 99.01 to this Current Report on Form 8-K.

Item 9.01. Financial Statements and Exhibits. (d) Exhibits Exhibit Description ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 99.01 Sales and Marketing Agreement Between Vertiv and Tecogen Regarding Data Center Cooling Applications SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Company has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized. TECOGEN INC. By: /s/ Abinand Rangesh March 3, 2025 Abinand Rangesh, Chief Executive Officer