Exhibit 5.1

	1271 Avenue of the Americas
	New York, New York 10020-1401
	Tel: +1.212.906.1200 Fax: +1.212.751.4864
	www.lw.com
	FIRM / AFFILIATE OFFICES
	Austin	Milan
	Beijing	Moscow
	Boston	Munich
	Brussels	New York
	Century City	Orange County
October 28, 2021	Chicago	Paris
	Dubai	Riyadh
	Düsseldorf	San Diego
Fluence Energy, Inc.	Frankfurt	San Francisco
4601 Fairfax Drive, Suite 600	Hamburg	Seoul
Arlington, Virginia 22203	Hong Kong	Shanghai
	Houston	Silicon Valley
	London	Singapore
	Los Angeles	Tokyo
	Madrid	Washington, D.C.

Ladies and Gentlemen:

We have acted as special counsel to Fluence Energy, Inc., a Delaware corporation (the “Company”), in connection with the preparation and filing by the Company on the date hereof with the Securities and Exchange Commission (the “Commission”) of a Registration Statement (the “Registration Statement”) on Form S-8 under the Securities Act of 1933, as amended (the “Act”), relating to the issuance of up to 23,988,371 shares of Class A common stock of the Company, par value $0.00001 per share (the “Shares”), which may be issued pursuant to the Fluence Energy, Inc. 2021 Incentive Award Plan (the “Incentive Plan”), the Fluence Energy, LLC Phantom Equity Incentive Plan (the “Phantom Plan”) and the 2020 Unit Option Plan of Fluence Energy, LLC (the “Unit Option Plan” and, together with the Incentive Plan and the Phantom Plan, the “Plans”). This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or related prospectus, other than as expressly stated herein with respect to the issuance of the Shares.

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the General Corporation Law of the State of Delaware (the “DGCL”), and we express no opinion with respect to any other laws.

October 28, 2021

Page 2

Subject to the foregoing and the other matters set forth herein, it is our opinion that as of the date hereof, when the Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the purchasers, and have been issued by the Company for legal consideration in excess of par value in the circumstances contemplated by the Plans, assuming in each case that the individual issuances, grants or awards under the Plans are duly authorized by all necessary corporate action and duly issued, granted or awarded and exercised in accordance with the requirements of law and the Plans (and the agreements duly adopted thereunder and in accordance therewith), the issue and sale of the Shares will have been duly authorized by all necessary corporate action of the Company, and such Shares will be validly issued, fully paid and non-assessable. In rendering the foregoing opinion, we have assumed that the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the DGCL.

This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Registration Statement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.