FLNC · Quarterly Report (Form 10-Q) · Filed February 4, 2026

Fluence Energy Inc — 10-Q exhibit

exhibit101-fluencexspthold.htm

Document

Exhibit 10.1

REGISTRATION RIGHTS AGREEMENT JOINDER

The undersigned is executing and delivering this Joinder pursuant to the Registration Rights Agreement dated as of November 1, 2021 (as the same may hereafter be amended, the “Registration Rights Agreement”), among Fluence Energy, Inc., a Delaware corporation (the “Corporation”), and the other person named as parties therein.

By executing and delivering this Joinder to the Corporation, and upon acceptance hereof by the Corporation upon the execution of a counterpart hereof, the undersigned hereby agrees to become a party to, to be bound by, and to comply with the provisions of the Registration Rights Agreement as a Holder of Registrable Securities in the same manner as if the undersigned were an original signatory to the Registration Rights Agreement, and the undersigned’s shares of Class A Common Stock shall be included as Registrable Securities under the Registration Rights Agreement to the extent provided therein. The Corporation is directed to add the address below the undersigned’s signature on this Joinder to the Schedule of Holders attached to the Registration Rights Agreement.

[Signature Pages Follow]

Accordingly, the undersigned has executed and delivered this Joinder as of the day of October 14, 2025.

SPT Holding, SARL

By: /s/ Gruenewald Thomas

Name: Gruenewald Thomas

Title: CEO

By: /s/ Stoffel Denis

Name: Stoffel Denis

Title: CFO

Agreed and Accepted as of October 14, 2025

Fluence Energy, Inc.

By: /s/ Vincent W. Mathis

Name: Vincent W. Mathis

Its: SVP, Chief Legal and Compliance Officer & Secretary

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