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                                                                     EXHIBIT 5.1



                                         September 8, 1998



AstroPower, Inc.
Solar Park
Newark, Delaware 19716-2000

Ladies and Gentlemen:

          We have acted as counsel to AstroPower, Inc., a Delaware corporation
(the "Company"), in connection with the registration under the Securities Act of
1933 (the "Act") of an aggregate of 1,960,000 shares (the "Shares") of the
Company's common stock, $.01 par value (the "Common Stock"), of which (i) 62,173
Shares are issued and outstanding, (ii) 1,737,827 Shares are to be offered upon
the terms and subject to the conditions set forth in the AstroPower, Inc. 1989
Stock Option Plan, and (iii) 160,000 Shares are to be offered upon the terms and
subject to the conditions set forth in the AstroPower, Inc. 1998 Non-Employee
Directors Stock Option Plan (collectively the "Plans").

          In connection therewith, we have examined or considered originals or
copies, certified or otherwise identified to our satisfaction, of the Amended
and Restated Certificate of Incorporation of the Company, the Amended and
Restated By-laws of the Company, the Plans, records of relevant corporate
proceedings with respect to the offering of the Shares and such other documents,
instruments and corporate records as we have deemed necessary or appropriate for
the expression of the opinions contained herein.  We have also reviewed the
Company's Registration Statement on Form S-8 (the "Registration Statement") to
be filed with the Securities and Exchange Commission with respect to the Shares.

          We have assumed the authenticity and completeness of all records,
certificates and other instruments submitted to us as originals, the conformity
to original documents of all records, certificates and other instruments
submitted to us as copies, the authenticity and completeness of the originals of
those records, certificates and other instruments submitted to us as copies and
the correctness of all statements of fact contained in all records, certificates
and other instruments that we have examined.

          Based on the foregoing and having regard for such legal considerations
as we have deemed relevant, we are of the opinion that the Shares have been duly
and validly authorized for the issuance and, that the Shares issued and
outstanding are and that the Shares to be issued, when issued in accordance with
the terms of the applicable Plan will be, duly and validly issued, fully paid
and nonassessable.

          The foregoing opinion is limited to the federal law of the United
States of America and the General Corporation Law of the State of Delaware, and
we are expressing no opinion as to the effect of the laws of any other
jurisdiction.

          We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the use of our name under the caption "Item 5.
Interests of Named Experts and Counsel" in the Registration Statement and under
the heading "Legal Matters" in the Prospectus.

                                         Sincerely,

                                         Opton Handler Feiler & Landau, LLP


                                         By: /s/ Peter Landau
                                             ----------------------
                                                 Peter Landau
