JOINT FILING AGREEMENT
Exhibit 1
Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby
agree that only one statement containing the information required by Schedule 13D need be filed on
behalf of the undersigned with respect to the ownership of shares of Common Stock of Distributed
Energy Systems Corp.
This agreement may be executed in any number of counterparts, each of which shall be deemed an
original.
| Dated: June 11, 2007. | PERSEUS PARTNERS VII, L.P. | |||
| By: | Perseus Partners VII GP, L.P., its general partner |
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| By: | Perseus Partners VII GP, L.L.C., its general partner |
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| /s/ Xxxxxxx X. Xxxxx | ||||
| Its: Senior Managing Director | ||||
| XXXXX X. XXXXX | ||||
| /s/ Xxxx Xxxxxxx, Attorney-In-Fact | ||||
| Xxxx Xxxxxxx, Attorney-In-Fact | ||||
