Item 7.01. Regulation FD Disclosure. On September 17, 2025, Tecogen Inc., a Delaware corporation(“ Company”), posted on its website at www. Tecogen. com in the section identified as “ Investors/Presentations” a document entitled “ Frequently Asked Questions - Tecogen Chillers for Artificial (AI) Data Centers,” a copy of which is filed as Exhibit 99.1 hereto. The document provides responses to certain questions the Company has received from its stockholders, analysts and others relating to the intended use of Tecogen Chillers for Artificial Intelligence (AI) Data Centers.

Item 9.01. Financial Statements and Exhibits. (d) Exhibits Exhibit Description ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 99.1 Frequently Asked Questions - C hillers for Artificial Intelligence (AI) Data Centers, filed herewith 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 September 17, 2025 Abinand Rangesh, Chief Executive Officer