Exhibit 5.1

Carroll Legal LLC

1449 Wynkoop Street

Suite 507

Denver, CO 80202

December 23, 2025

Ascent Solar Technologies, Inc.

12300 Grant Street

Thornton, CO 80241

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as special counsel to Ascent Solar Technologies, Inc., a Delaware corporation (the “Company”), in connection with the Company’s Registration Statement on Form S-3 (the “Registration Statement”) under the Securities Act of 1933, as amended (the “Securities Act”).

The Registration Statement relates to the offer and sale by the selling stockholders identified therein of up to 3,148,724 shares of the Company’s common stock, par value $0.0001 per share (the “Common Stock”). Such shares of Common Stock consist of: (i) 769,232 shares of Common Stock (the “Shares”), (ii) 256,411 shares of Common Stock (the “Pre-Funded Warrant Shares”) issuable upon the exercise of pre-funded warrants (the “Pre-Funded Warrants”); (iii) 1,025,643 shares of Common Stock (the “Series A Common Warrant Shares”) issuable upon the exercise of Series A common warrants (the “Series A Common Warrants”); (iv) 1,025,643 shares of Common Stock (the “Series B Common Warrant Shares”) issuable upon the exercise of Series B common warrants (the “Series B Common Warrants”); and (v) 71,795 shares of Common Stock (the “PA Warrant Shares” and together with the Pre-Funded Warrant Shares, the Series A Common Warrant Shares and the Series B Common Warrant Shares, the “Warrant Shares”) issuable upon the exercise of placement agent warrants (the “PA Warrants” and together with the Pre-Funded Warrants, the Series A Common Warrants and the Series B Common Warrants, the “Warrants”).

In connection herewith, we have examined the Registration Statement. We have also examined originals or copies, certified or otherwise identified to our satisfaction, of the Company’s Certificate of Incorporation and Bylaws (both as amended to date), and such other records, agreements and instruments of the Company, certificates of public officials and officers of the Company, and such other documents, records and instruments, and we have made such legal and factual inquiries, as we have deemed necessary or appropriate as a basis for us to render the opinions hereinafter expressed.

In our examination of the foregoing, we have assumed the genuineness of all signatures, the legal competence and capacity of natural persons, the authenticity of documents submitted to us as originals and the conformity with authentic original documents of all documents submitted to us as copies or by facsimile or other means of electronic transmission, or which we obtained from the Commission’s Electronic Data Gathering, Analysis and Retrieval system (“Edgar”) or other sites maintained by a court or governmental authority or regulatory body and the authenticity of the originals of such latter documents. If any documents we examined in printed, word processed or similar form has been filed with the Commission on Edgar or such court or governmental authority or regulatory body, we have assumed that the document so filed is identical to the document we examined except for formatting changes. When relevant facts were not independently established, we have relied without independent investigation as to matters of fact upon statements of governmental officials and certificates and statements of appropriate representatives of the Company.

Based upon the foregoing and in reliance thereon, and subject to the assumptions, comments, qualifications, limitations and exceptions set forth herein, we are of the opinion, that:

(i)       the Shares have been duly authorized, validly issued, and are fully paid and non-assessable;

(ii)       the Warrant Shares, when issued upon exercise of the Warrants against payment therefor as set forth in the Registration Statement, will be duly authorized, validly issued, fully paid and non-assessable.

Our opinions herein reflect only the application of the General Corporation Law of the State of Delaware. The opinions set forth herein are made as of the date hereof and are subject to, and may be limited by, future changes in factual matters, and we undertake no duty to advise you of the same. The opinions expressed herein are based upon the law in effect (and published or otherwise generally available) on the date hereof, and we assume no obligation to revise or supplement these opinions should such law be changed by legislative action, judicial decision or otherwise. In rendering our opinions, we have not considered, and hereby disclaim any opinion as to, the application or impact of any laws, cases, decisions, rules or regulations of any other jurisdiction, court or administrative agency.

We do not render any opinions except as set forth above. We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement and to the use of our name under the caption “Legal Matters” in the prospectus filed as a part thereof. In giving such consent, we do not thereby concede that we are within the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.

CARROLL LEGAL LLC
By:	/s/ James H. Carroll
	James H. Carroll
	Managing Member