Filed Pursuant to Rule 424(b)(5)
 Registration No. 333-287577
PROSPECTUS SUPPLEMENT NO. 1
(To Prospectus Supplement dated August 15, 2025)
(To Prospectus dated May 27, 2025)
$1,000,000,000
Common Stock
This supplement amends, supplements and updates
the prospectus supplement, dated August 15, 2025 (collectively, the “prospectus supplement”), relating to the sale of our
shares of common stock having an aggregate offering price of up to $1,000,000,000, from time to time through or to B. Riley Securities,
Inc. (“B. Riley Securities”) as sales agent or principal pursuant to that certain At Market Issuance Sales Agreement, dated
January 17, 2024, as amended by Amendment No. 1, dated February 23, 2024, Amendment No. 2, dated November 7, 2024, and Amendment No. 3,
dated August 15, 2025 (collectively, the “Sales Agreement”).
On September 29, 2025, we entered into Amendment
No. 4 to the Sales Agreement in order to add Yorkville Securities, LLC (“Yorkville Securities”) as an additional sales agent
and/or principal through which we may offer and sell shares of our common stock pursuant to the Sales Agreement. All reference in the
prospectus supplement to B. Riley Securities are hereby amended to include Yorkville Securities and all references to the sales agent
are hereby amended to refer to each sales agent or the sales agents, as the context may require.
Our common stock is listed on the Nasdaq Capital
Market under the symbol “PLUG.” On September 29, 2025, the last reported sale price of our common stock on the Nasdaq Capital
Market was $2.27 per share.
Investing in our securities involves a high degree
of risk. You should review carefully the risks and uncertainties referenced under the heading “Risk Factors” beginning on
page S-6 of the prospectus supplement, dated August 15, 2025, and in the other documents
that are incorporated by reference in the prospectus supplement and the accompanying prospectus.
Neither the Securities and Exchange Commission
nor any state securities commission has approved or disapproved of these securities or determined if this supplement, the prospectus supplement
or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
B. Riley Securities |
Yorkville Securities |
The date of this supplement is September 30, 2025.