EXHIBIT A JOINT FILING AGREEMENT
EXHIBIT A
The undersigned hereby agree that the Statement on Schedule 13D, dated March 22, 2007, with
respect to the common shares, par value $0.0001 per share, of Ascent Solar Technologies, Inc. is,
and any amendments thereto executed by each of us shall be, filed on behalf of each of us pursuant
to and in accordance with the provisions of Rule 13d-1(k)(1) under the Securities Exchange Act of
1934, as amended, and that this Agreement shall be included as an Exhibit to the Schedule 13D and
each such amendment. Each of the undersigned agrees to be responsible for the timely filing of the
Schedule 13D and any amendments thereto, and for the completeness and accuracy of the information
concerning itself contained therein. This Agreement may be executed in any number of counterparts,
all of which taken together shall constitute one and the same instrument.
IN WITNESS WHEREOF, the undersigned have executed this Agreement as of the 22 day of March,
2007.
| NORSK HYDRO ASA |
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| By: | /s/ Xxxxxx X. Xxxxxx Rostrup | |||
| Name: | Xxxxxx X. Xxxxxx Rostrup | |||
| Title: | Senior Vice President | |||
| NORSK HYDRO PRODUKSJON AS |
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| By: | /s/ Xxxxxx X. Xxxxxx Rostrup | |||
| Name: | Xxxxxx X. Xxxxxx Rostrup | |||
| Title: | Chief Executive Officer | |||
