1 EXHIBIT A JOINT FILING AGREEMENT The undersigned each agree that (i) the statement on Schedule 13G relating to the common stock, par value $0.01 per share, of NewPower Holdings, Inc. has been adopted and filed on behalf of each of them, (ii) all...

   1
                                                                      EXHIBIT A

                             JOINT FILING AGREEMENT

         The undersigned each agree that (i) the statement on Schedule 13G
relating to the common stock, par value $0.01 per share, of NewPower Holdings,
Inc. has been adopted and filed on behalf of each of them, (ii) all future
amendments to such statement on Schedule 13G will, unless written notice to the
contrary is delivered as described below, be jointly filed on behalf of each of
them, and (iii) the provisions of Rule 13d-1(k)(1) under the Securities
Exchange Act of 1934 apply to each of them. This agreement may be terminated
with respect to the obligation to jointly file future amendments to such
statement on Schedule 13G as to any of the undersigned upon such person giving
written notice thereof to each of the other persons signatory hereto, at the
principal office thereof.

         EXECUTED as of May 14, 2001

                                       ENRON CORP.


                                       By: /s/ XXXXXX X. XXXXX
                                          -------------------------------------
                                       Name:    Xxxxxx X. Xxxxx
                                       Title:   Managing Director, and
                                                Controller


                                       ENRON ENERGY SERVICES, LLC


                                       By: /s/ XXXX X. XXXXXX
                                          -------------------------------------
                                       Name:    Xxxx X. Xxxxxx
                                       Title:   President, New Business Ventures


                                       XXXXXX ENERGY SERVICES, LLC

                                       By:      Enron Energy Services, LLC,
                                                its Managing Member


                                                By: /s/ XXXX X. XXXXXX
                                                   ----------------------------
                                                Name:    Xxxx X. Xxxxxx
                                                Title:   President, New Business
                                                         Ventures


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                                       MCGARRET I, L.L.C.

                                       By:      Enron Energy Services, LLC,
                                                its Managing Member


                                                By: /s/ XXXX X. XXXXXX
                                                   ----------------------------
                                                Name:    Xxxx X. Xxxxxx
                                                Title:   President, New Business
                                                         Ventures


                                       MCGARRET II, L.L.C.

                                       By:      Enron Energy Services, LLC,
                                                its Managing Member


                                                By: /s/ XXXX X. XXXXXX
                                                   ----------------------------
                                                Name:    Xxxx X. Xxxxxx
                                                Title:   President, New Business
                                                         Ventures


                                       MCGARRET III, L.L.C.

                                       By:      Enron Energy Services, LLC,
                                                its Managing Member


                                                By: /s/ XXXX X. XXXXXX
                                                   ----------------------------
                                                Name:    Xxxx X. Xxxxxx
                                                Title:   President, New Business
                                                         Ventures


                                       EES WARRANT TRUST

                                       By:      Wilmington Trust Company,
                                                Not in its individual capacity,
                                                but solely as Trustee


                                                By: /s/ XXX X. XXXXXXX
                                                   ----------------------------
                                                Name:    Xxx X. Xxxxxxx
                                                Title:   Assistant Vice
                                                         President