Document:

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                                                                    Exhibit 10.7

211 Second Avenue,
Waltham, MA 02154 USA
TL: 781.890.7117    FX: 781.890.7141

MARK A. FARBER
President

February 26, 1999

Dr. Emanuel Sachs
[CONFIDENTIAL TREATMENT REQUESTED]/*/
[CONFIDENTIAL TREATMENT REQUESTED]/*/

Dear Ely:

Please acknowledge the following changes to our License and Consulting Agreement
dated September 30, 1994:

     -    Effective January 1, 1999, the consulting fee will be raised to
$ [CONFIDENTIAL TREATMENT REQUESTED] /*/ per hour.
     -    The Minimum Royalty, as specified in Exhibit B, will be changed for
          the year 1998 only from $ [CONFIDENTIAL TREATMENT REQUESTED] /*/ to
          [CONFIDENTIAL TREATMENT REQUESTED] /*/. The rest of the Minimum
          Royalty schedule will remain unchanged.

Please sign both copies of this letter and return one to me.

Sincerely,

/s/ Mark A. Farber
     President

/s/ Emanuel M. Sachs
----------------------------
Emanuel M. Sachs

/*/ [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.
<PAGE>   2

                                    AGREEMENT

     This Agreement is made and entered into as of the 30th day of September,
1994, by and between Evergreen Solar, Inc., of 76 Ten Hills Road, Somerville,
Massachusetts 02145 (hereinafter "EVERGREEN"), and Emanuel M. Sachs, of 18
Moreland Avenue, Newton, Massachusetts 02159 (hereinafter "SACHS").

                                   WITNESSETH

     WHEREAS, EVERGREEN is engaged in the development and marketing of products
which incorporate ribbon technology, such as crystalline silicon photovoltaics
and photovoltaic solar cells;

     WHEREAS, SACHS owns or has rights in and to certain patents, patent rights,
know-how and technology relating to ribbon technology and is desirous of
granting an exclusive license in and to all of such patents, patent rights,
know-how and technology to EVERGREEN;

     WHEREAS, EVERGREEN desires to obtain a license under such patents, patent
rights, know-how and technology upon the terms and conditions hereinafter set
forth;

     WHEREAS, SACHS desires to provide consulting services to EVERGREEN in the
area of ribbon technology;

     WHEREAS, EVERGREEN desires to purchase the consulting services of SACHS in
accord with the terms and conditions hereinafter set forth;

         NOW, THEREFORE, in consideration of the mutual covenants expressed
herein and other good and valuable consideration, receipt and sufficiency of
which is hereby acknowledged, EVERGREEN and SACHS agree as follows:

                             ARTICLE I - DEFINITIONS

     1.1  "Licensed Patents" shall mean patents as set forth in EXHIBIT A of
this Agreement.

     1.2  "Valid Claim" shall mean any issued claim of a Licensed Patent which
has not lapsed or expired, or has not been determined invalid or unenforceable
by a court of proper jurisdiction in an unappealed and unappealable decision.

     1.3  "Wafer" shall mean any ribbon substrate which would infringe a claim
of a Licensed Patent.

     1.4  "Cell" shall mean a single Wafer which is processed to provide
electrical output.

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<PAGE>   3

     1.5  "Module" shall mean a plurality of Cells which are connected with a
common electrical output.

     1.6  "Integrated Product" shall mean any product which is sold as a unit by
EVERGREEN and which incorporates a Wafer, Cell or Module as part of the unit.

     1.7  "Other Product" shall mean any product, other than a Wafer, Cell,
Module or Integrated Product, which would infringe a claim of a Licensed
Patent.

     1.8  "Technology" shall mean all technology, including knowledge, know-how,
techniques, materials, products, trade secrets, data, methods, processes,
inventions (whether or not patentable) and intellectual property rights in and
to the Licensed Patents, and including, without limitation, ribbon technology,
developed or otherwise owned by SACHS, which was developed, conceived, or
written in connection with the inventions of the Licensed Patents and which
otherwise aids in the practice of the inventions set forth in the Licensed
Patents; and all technology developed, conceived, written, and made in
connection with this Agreement.

     1.9  (A)  "EVERGREEN Confidential Information" shall mean any information
or Technology of a confidential or proprietary nature which is disclosed by
EVERGREEN to SACHS or which is developed or licensed pursuant to this Agreement,
including, but not limited to, all technical data, engineering information,
computer programs, drawings, blueprints, descriptions, know-how, samples,
marketing plans, business strategy, and financial projections. EVERGREEN
Confidential Information shall not include any information or data which (i) is
in or becomes part of the public domain by any means other than breach of
obligations hereunder, (ii) was known by SACHS at the time of disclosure, or
(iii) is, at any time, disclosed to SACHS by a third party having right to
disclose the same.

          (B)  "SACHS Confidential Information" shall mean any information or
Technology of a confidential or proprietary nature which is disclosed by SACHS
to EVERGREEN and which is outside the scope of the consulting services to be
provided by SACHS to EVERGREEN pursuant to Article IV of this Agreement,
including, but not limited to, all technical data, engineering information,
computer programs, drawings, blueprints, descriptions, know-how, samples,
marketing plans, business strategy, and financial projections. SACHS
Confidential Information shall not include any information or data which (i) is
in or becomes part of the public domain by any means other than breach of
obligations hereunder, (ii) was known by EVERGREEN at the time of disclosure, or
(iii) is, at any time, disclosed to EVERGREEN by a third party having right to
disclose the same.

     1.10 "Kilowatt" shall mean the unit of measure of electrical output of a
Cell or Module which is in a normal condition for sale by EVERGREEN; and shall
be defined as the Direct Current Power Output, defined below, of such a Cell or
Module under standard test conditions which include (i) 1000 watts per square
meter of solar irradiance; (ii) an AM 1.5 spectrum; and (iii) a cell temperature
of 25 degrees Centigrade. "Direct Current Power Output" shall mean the peak
power output of such a Cell or Module, or the warranty power rating of such a
Cell or Module, whichever is less.

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     1.11 "Net Wafer Revenue" shall mean the sales price or the fair market
value of any other consideration actually received by EVERGREEN from sales to
EVERGREEN's customers of Wafers less any (i) amounts repaid or credited due to
retroactive price reductions or due to rejections or returns, (ii) trade or
quantity discounts allowed and taken, (iii) amounts written off as a result of
retroactive price reductions, (iv) customs, duties, sales, use or similar taxes,
(v) freight and insurance charges, (vi) collection costs, and (vii) amounts
discounted or owed from sales to, or licenses with, the United States
Government.

     1.12 "Net Cell Revenue" shall mean the sales price or the fair market value
of any other consideration actually received by EVERGREEN from sales to
EVERGREEN's customers of Cells, less any amounts specified in Article
1.11(i)-(vii).

     1.13 "Net Module Revenue" shall mean the sales price or the fair market
value of any other consideration actually received by EVERGREEN from sales to
EVERGREEN's customers of Modules, less any amounts specified in Article
1.11(i)-(vii).

     1.14 (A)  In the event that a Wafer is sold within an Integrated Product
without a Cell, the Net Wafer Revenue shall mean the usual selling price of the
Wafer when sold separately, less any amounts specified in Article 1.11(i)-(vii);
or, in the absence of such usual selling price for such Wafer, shall correspond
to the usual selling price of wafers sold separately by competitors of EVERGREEN
which are of similar type, kind or utility as the Wafer, less any amounts
specified in Article 1.11(i)-(vii).

          (B)  In the event that a Cell is sold within an Integrated Product
without a Module, the Net Cell Revenue shall mean the usual selling price of the
Cell when sold separately, less any amounts specified in Article 1.11(i)-(vii);
or, in the absence of such usual selling price for such Cell, shall correspond
to the usual selling price of cells sold separately by competitors of EVERGREEN
which are of similar type, kind or utility as the Cell, less any amounts
specified in Article 1.11(i)-(vii).

          (C)  In the event that the Module is sold within an Integrated
Product, the Net Module Revenue shall mean the usual selling price of the Module
when sold separately, less any amounts specified in Article 1.11(i)-(vii); or,
in the absence of such usual selling price for such Module, shall correspond to
the usual selling price of modules sold separately by competitors of EVERGREEN
which are of similar type, kind or utility as the Module, less any amounts
specified in Article 1.11(i)-(vii).

     1.15 "Net Other Product Revenue" shall correspond to the fair market value
attributable to sales to EVERGREEN's customers of Other Products as the parties
hereto agree in writing and after good faith negotiations, less any amounts
specified in Article 1.11(i)-(vii); or, in the absence of such agreed-to value,
the Net Other Product Revenue shall correspond to the respective valuation of
technology within the Other Product and covered by the Licensed Patents to the
overall valuation of the Other Product, less any amounts specified in Article
1.11(i)-(vii).

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     1.16. "Protected Country" shall mean a country where the manufacture, sale
or use of a Wafer, Cell, Module, Integrated Product or Other Product would
infringe a Valid Claim of a Licensed Patent in that country.

     1.17 "Unprotected Country" shall mean a country where the manufacture, sale
and use of a Wafer, Cell, Module, Integrated Product or Other Product would not
infringe a Valid Claim of a Licensed Patent in that country.

                               ARTICLE II - GRANT

     SACHS hereby grants to EVERGREEN, its successors, assigns, and legal
representatives, the irrevocable, except as provided herein, world-wide right
and license in and to the Technology and the Licensed Patents, including the
right to make, have made, use, lease, sub-license and sell Wafers, Cells,
Modules, Integrated Products and Other Products and to enforce any of the patent
rights of the Licensed Patents. Such license shall be exclusive, except for
rights to the Licensed Patents held by the U.S. Department of Energy'(the "DOE")
pursuant to the (i) Settlement Agreement, dated October 17, 1983, by and among
the DOE, SACHS, Theodore F. Ciszek, Jeffery L. Hurd and Arthur D. Little and
(ii) two DOE contracts (nos. XW-1-1069-1 and ZB-3-03009-1).

                            ARTICLE III - ROYALTIES

     3.1  SACHS shall earn a royalty of [CONFIDENTIAL TREATMENT REQUESTED]/*/ of
the Net Wafer Revenue from Wafers made, used or sold by EVERGREEN in, or made or
sold by EVERGREEN for delivery to Protected Countries, during the term of this
Agreement. SACHS shall earn a royalty of [CONFIDENTIAL TREATMENT REQUESTED]/*/
of the Net Wafer Revenue from Wafers made, used and sold by EVERGREEN in
Unprotected Countries, during the term of this Agreement.

     3.2  For the first [CONFIDENTIAL TREATMENT REQUESTED]/*/ Kilowatts of
combined electrical output of Cells, Modules and Integrated Products made, used
or sold by EVERGREEN in, or made or sold by EVERGREEN for delivery to, Protected
Countries and Unprotected Countries, SACHS shall earn royalties for such Cells,
Modules and Integrated Products at the following rates:

          (A)  For Cells, Modules and Integrated Products made, used or sold by
EVERGREEN in, or made or sold by EVERGREEN for delivery to Protected Countries,
SACHS shall earn royalties at the rate of:

               (i)  [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Cell
                    Revenue; and

               (ii) [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Module
                    Revenue.

          (B)  For Cells, Modules and Integrated Products made, used and sold by
EVERGREEN in Unprotected Countries, SACHS shall earn royalties at the rate of:

               (i)  [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Cell
                    Revenue; and

/*/ [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

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               (ii) [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Module
                    Revenue.

     3.3  After the first [CONFIDENTIAL TREATMENT REQUESTED]/*/ kilowatts of
combined electrical output of Cells, Modules and Integrated Products made, used
or sold by Evergreen in, or made or sold by EVERGREEN for delivery to, Protected
Countries and Unprotected Countries, SACHS shall earn royalties for such Cells,
Modules and Integrated Products at the following rates:

          (A)  For Cells, Modules and Integrated Products made, used or sold by
EVERGREEN in, or made or sold by EVERGREEN for deliver to, Protected Countries,
SACHS shall earn royalties at the rate of:

               (i)  [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Cell
                    Revenue; and

               (ii) [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Module
                    Revenue.

          (B)  For Cells, Modules and Integrated Products made, used and sold by
EVERGREEN in Unprotected Countries, SACHS shall earn royalties at the rate of:

               (i)  [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Cell
                    Revenue; and

               (ii) [CONFIDENTIAL TREATMENT REQUESTED]/*/ of the Net Module
                    Revenue.

     3.4  SACHS shall earn a royalty of [CONFIDENTIAL TREATMENT REQUESTED]/*/ of
the Net Other Product Revenue from Other Products made, used or sold by
EVERGREEN in, or made or sold by EVERGREEN for delivery to, Protected Countries,
during the term of this Agreement. SACHS shall earn a royalty of [CONFIDENTIAL
TREATMENT REQUESTED]/*/ of the Net Other Product Revenue from Other Products
made, used and sold by EVERGREEN in Unprotected Countries, during the term of
this Agreement.

     3.5  Commencing in 1998, if the aggregate annual royalties paid or payable
to SACHS under this Agreement for any 12-month calendar year (the "Measurement
Year") are less than the amount set forth on EXHIBIT B hereto opposite such
Measurement Year (the "Minimum Royalty"), EVERGREEN shall have the right and
option to pay SACHS, within forty-five (45) days after the last day of the
Measurement Year, the Minimum Royalty in lieu of the royalty payments otherwise
paid or payable to SACHS under this Agreement for such Measurement Year, in
which event EVERGREEN shall retain all of its rights and to the license granted
by SACHS under this Agreement; provided, however, that if EVERGREEN fails,
within forty-five (45) days after the last day of any Measurement Year to pay
SACHS the greater of the Minimum Royalty or the royalty payments otherwise due
under this Agreement for such Measurement Year, SACHS shall have the right to
terminate this Agreement and all of the rights, privileges and license granted
hereunder in accordance with Article VII, except that, in this instance only,
this Agreement automatically shall terminate as of the last day of the cure
period set forth in Section 7.2 of this Agreement if EVERGREEN fails to cure its
nonpayment under this Section 3.5 within such cure period, without any
requirement of arbitration.

/*/ [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

                                      -6-
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     3.6  Any royalties payable to SACHS under this Agreement shall be paid to
SACHS by EVERGREEN within forty-five (45) days after the conclusion of the
calendar-year quarter during which such royalties were earned. At the time of
the payment of any royalties to SACHS, EVERGREEN also shall provide SACHS with
an accounting of the sales of products upon which the royalties were based and
all material costs associated with such sales, including, without limitation,
all deductions pursuant to Section 1.11(i)-(vii). Any overdue royalty payments
shall bear interest at a rate equal to the prime rate on the date such royalties
were initially due. Any revenues earned on sales of covered products in foreign
countries shall be converted to American dollars for purposes of calculating
royalties due SACHS under this Agreement at the exchange rate in effect on the
last day of the calendar-year quarter in which the foreign sales occurred.

     3.7  EVERGREEN may sublicense any of its rights and interests in and to
this Agreement, including, without limitation, its rights and interests in and
to the Licensed Patents and the Technology; and, in such event, SACHS shall earn
royalties with respect to sales by EVERGREEN sublicensees of Wafers, Cells,
Modules, Integrated Products and Other Products in accordance with this Article
III, which shall be payable by EVERGREEN. Evergreen shall keep records of all
transactions by its sublicensees with respect to Wafers, Cells, Modules,
Integrated Products and Other Products, in accordance with Section 10.2 of this
Agreement.

                    ARTICLE IV - CONSULTING SERVICES OF SACHS

     4.1  Simultaneously with the execution of this Agreement, EVERGREEN shall
issue and sell to SACHS [CONFIDENTIAL TREATMENT REQUESTED]/*/ shares of Common
Stock, par value $.01 per share, of EVERGREEN ("Common Stock") at a price of
[CONFIDENTIAL TREATMENT REQUESTED]/*/ per share in connection with the
consulting services of SACHS to be performed in accordance with Article 4.2. In
connection with his purchase of Common Stock, SACHS has executed a Stock
Restriction Agreement with EVERGREEN, of even date herewith (the "Stock
Restriction Agreement") in substantially the form attached hereto as EXHIBIT C,
and is subject to all terms and conditions therein.

     4.2  EVERGREEN shall have the right, but not the obligation, to demand the
consulting services of SACHS; and SACHS shall be obligated, upon demand by
EVERGREEN, to spend up to (i) [CONFIDENTIAL TREATMENT REQUESTED]/*/ hours during
the first three-month period after October 1, 1994, (ii) [CONFIDENTIAL TREATMENT
REQUESTED]/*/ hours in each of the second, third, and fourth three-month periods
after October 1, 1994, and (iii) [CONFIDENTIAL TREATMENT REQUESTED]/*/ hours in
each of the three-month periods thereafter until [CONFIDENTIAL TREATMENT
REQUESTED]/*/, to provide advice and consultation to EVERGREEN with respect to
the design, development, enhancement, modification, pursuit and defense of the
Technology, including without limitation the Licensed Patents, and marketing and
manufacturing of Wafers, Cells, Modules, Integrated Products, Other Products and
the Technology in accordance with EVERGREEN's reasonable requests.

     4.3  EVERGREEN shall pay SACHS [CONFIDENTIAL TREATMENT REQUESTED]/*/ per
hour for every hour actually spent by SACHS to fulfill his obligations of
Article IV. Such pay shall be paid to SACHS on a monthly basis within 30 days of
presentation to EVERGREEN of an invoice therefor with all necessary supporting
documentation EVERGREEN shall reimburse SACHS for reasonable and necessary
out-of-pocket expenses incurred by SACHS during the term of this

/*/ [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

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Agreement in connection with his provision of consulting services hereunder (the
"Expenses"), provided that such Expenses are properly deductible to EVERGREEN
and accounted for in accordance with the requirements of the Internal Revenue
Service; and provided also that Expenses shall not exceed $100 in any month
unless authorized in advance and in writing by EVERGREEN.

     4.4  All research, technical data, and other information, discoveries,
inventions or improvements thereto, designs, trademarks, formulas, products or
plans conceived of or discovered by SACHS, whether solely or jointly with others
during the course of and within the scope of the consulting services performed
for EVERGREEN, including all technology directly relating to the Licensed
Patents and whether or not such invention or improvement is made at the request
or suggestion of EVERGREEN or in accordance with its plans and proposals, shall
be the sole property of EVERGREEN, and, either during the course of such
consulting services or thereafter, SACHS will promptly and fully disclose to
EVERGREEN or its authorized representative, successors or assigns, all such
inventions and improvements, and will execute and deliver to EVERGREEN, or its
authorized representative, successors or assigns, all information, including
written applications, diagrams, plans or other documents, as may be necessary or
appropriate to patent, register, copyright, obtain, perfect, or explain any such
research data and other information, discoveries, inventions or improvements
thereto, formulas, designs, trademarks, products, or plans, and shall perform
such other acts as are necessary to perfect title in and to EVERGREEN; provided
that SACHS shall be compensated by EVERGREEN at the consulting rate set forth in
this Article IV for SACHS' assistance with respect to patent preparation or
prosecution.

     4.5  (A)  In the event that, at any time during any three-month period
ending on December 31, March 31, June 30 or September 30 of any year and
occurring between the date of this Agreement and [CONFIDENTIAL TREATMENT
REQUESTED]/*/ (individually, a "Consulting Period") (i) SACHS fails to perform
consulting services in accord with the demands by EVERGREEN under Article IV of
this Agreement, or (ii) SACHS fails to perform consulting services pursuant to
Article IV in a competent and professional manner consistent with industry
standards, EVERGREEN shall have the right and option (the "Purchase Option") to
purchase from SACHS, for a sum of [CONFIDENTIAL TREATMENT REQUESTED]/*/ per
share, and SACHS shall be required to sell to EVERGREEN at such price,
[CONFIDENTIAL TREATMENT REQUESTED]/*/ shares of Common Stock for each such
Consulting Period in which SACHS fails to perform required consulting services
or fails to perform consulting services in a competent and professional manner
consistent with industry standards, in accordance with Section 2 of the Stock
Restriction Agreement.

          (B)  If EVERGREEN determines at any time that SACHS' failure to
perform required consulting services or SACHS' failure to perform consulting
services in a competent and professional manner consistent with industry
standards is reasonably likely to recur in future Consulting Periods, EVERGREEN,
upon written notice to SACHS, may terminate this Agreement solely with respect
to the provision of future consulting services by SACHS without terminating any
other provisions of this Agreement, in which event SACHS shall be required to
sell to EVERGREEN, at a price of $.01 per share, all shares of Common Stock that
are still subject to the Purchase Option under the Stock Restriction Agreement
with respect to all future

/*/ [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT
TO RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

                                      -8-
<PAGE>   9

Consulting Periods; provided, however, that in the event that EVERGREEN's
determination that SACHS' failure to perform required consulting services or
SACHS' failure to perform consulting services in a competent and professional
manner consistent with industry standards is reasonably likely to recur in
future Consulting Periods is based on the death or "disability" (as defined in
the Stock Restriction Agreement) of SACHS, the number of shares of Common Stock
then subject to the Purchase Option for all future Consulting Periods shall be
reduced by fifty percent (50%).

               ARTICLE V - REPRESENTATIONS, COVENANTS, WARRANTIES

     5.1  SACHS represents and warrants to the best of his knowledge that he has
complied with all applicable laws with respect to the Licensed Patents and the
Technology.

     5.2  SACHS represents and warrants that, except as is set forth on EXHIBIT
D hereto, he has not previously entered into any material agreements or
contracts of any kind with respect to or affecting the Licensed Patents or the
Technology.

     5.3  SACHS represents and warrants to the best of his knowledge, but
without additional investigation or patent search, that each of the Licensed
Patents which has not lapsed are valid and enforceable, and that the practice of
the inventions set forth in the Licensed Patents do not conflict with, breach or
infringe any patent, copyright, trade secret, or other intellectual property
right of any third party, except for any conflicts which may exist with respect
to the agreements and contracts set forth on Exhibit D hereto.

     5.4  SACHS represents and warrants that he has disclosed or provided to
EVERGREEN all material information, documents, memoranda, notes, correspondence
and all other materials of any kind which are in his possession, or for which he
controls access, or are known by him or should be known by him, relating to any
claims or interests of any kind in and to the Licensed Patents and Technology
(the "Materials"). EXHIBIT E summarizes the Materials.

     5.5  SACHS represents and warrants to the best of his knowledge that there
are no actions, proceedings, litigation or claim of any kind currently pending
or threatened with respect to the Licensed Patents or the Technology, and no
existing grounds for any such claims.

     5.6  SACHS represents and warrants that he has full power and authority to
undertake the obligations set forth in this Agreement, and that by entering into
this Agreement and performing his obligations hereunder he will not violate or
conflict with the terms or provisions of any other agreement to which he is a
party or any other obligation by which he is bound.

                          ARTICLE VI - INDEMNIFICATION

     6.1  Except as limited in Article 6.2, SACHS shall indemnify and hold
EVERGREEN and its stockholders, directors and officers harmless from any and all
claims, actions, liabilities, losses, damages or expenses, including, without
limitation, reasonable attorneys' fees, arising from (i) SACHS' breach of any of
the representations, covenants, and warranties of Article V, or (ii) defaults by
SACHS in making royalty payments to the Department of Energy. SACHS'

                                      -9-
<PAGE>   10

obligations to indemnify EVERGREEN pursuant to this Article shall not survive
the expiration of this Agreement in the ordinary course pursuant to Section 7.1,
but shall survive any earlier termination of this Agreement.

     6.2  SACHS' aggregate liability under Article VI shall be limited to all
royalties paid to or vested in SACHS pursuant to this Agreement, and to any and
all future royalties, EVERGREEN stock and payments paid, owed to, or later
accrued by or vested in SACHS in performance thereof; and EVERGREEN shall have
the choice as to which of such royalties, stock, and payments shall be used as
indemnification or as payment of such liability.

                               ARTICLE VII - TERM

     7.1  The term of this Agreement shall extend until the expiration of all of
the claims of the Licensed Patents which have not lapsed or been determined
invalid or unenforceable by a court of proper jurisdiction in an unappealed and
unappealable decision.

     7.2  Should EVERGREEN fail in its remittance to SACHS of monies due in
accordance with this Agreement, SACHS shall have the right to serve upon
EVERGREEN, by certified mail at the address designated in ARTICLE X hereof,
notice of SACHS' desire to terminate this Agreement. If within thirty (30) days
after EVERGREEN's receipt of such notice, EVERGREEN shall not have paid all such
monies asserted by SACHS to be due and payable, SACHS may institute arbitration
proceedings in accordance with Article VIII of this Agreement seeking
termination of the rights, privileges and license granted hereunder. This
Article 7.2 shall always take precedence over any breach or default referred to
in Article 7.3.

     7.3  Upon any material breach or default of this Agreement by EVERGREEN,
other than those occurrences set out in Article 7.2 hereinabove, SACHS shall
have the right to serve upon EVERGREEN, by certified mail at the address
designated in ARTICLE X hereof, notice of SACHS' desire to terminate this
Agreement. If within sixty (60) days after EVERGREEN's receipt of such notice,
EVERGREEN shall not have cured such breach(es), SACHS may institute arbitration
proceedings in accordance with Article VIII of this Agreement seeking
termination of the rights, privileges and license granted hereunder.

     7.4  In addition to any other remedy available to EVERGREEN under this
Agreement or any applicable law, and without limiting in any respect any of
EVERGREEN'S rights under Section 4.5 of this Agreement and Section 2 of the
Stock Restriction Agreement, including, without limitation, its rights with
respect to the, Purchase Option, in the event of any material breach of SACHS'
warranties, covenants or representations set forth in this Agreement, EVERGREEN
shall have the right to serve upon SACHS by certified mail at the address
designated in ARTICLE X hereof, notice of EVERGREEN's desire to terminate this
Agreement. If, within thirty (30) days after SACHS' receipt of such notice SACHS
shall not have cured all such breaches, EVERGREEN may institute arbitration
proceedings in accordance with Article VIII of this Agreement seeking
termination of the rights, privileges and license granted hereunder. In the
event that this Agreement is terminated pursuant to such arbitration
proceedings, EVERGREEN shall be under no further obligation to pay to SACHS any
future

                                      -10-
<PAGE>   11

consulting payments or royalties whatsoever, and SACHS shall be required to sell
all unvested shares of EVERGREEN Common Stock to EVERGREEN at a price of $.01
per share.

     7.5  Upon termination of this Agreement for any reason, among other things:
(i) nothing herein, except as limited in Section 7.4, shall be construed to
release either party from any obligation that matured prior to the effective
date of such termination, and (ii) EVERGREEN shall assign to SACHS any of
EVERGREEN's right and interest in and to the Licensed Patents. In the event of
any termination, EVERGREEN shall make good faith attempts to provide SACHS with
technology which EVERGREEN does not intend to pursue or market so that SACHS can
independently pursue such technology.

                           ARTICLE VIII - ARBITRATION

     8.1  All claims, disputes or controversies arising under, out of, or in
connection with this Agreement, or any breach thereof, which have not been
resolved by good faith negotiations between the parties, shall be resolved by
final and binding arbitration in Boston, Massachusetts, or such other location
as the parties may mutually agree, under the rules of the American Arbitration
Association then obtaining, and judgment upon the award rendered by the
arbitrator may be entered in any court having jurisdiction thereof, provided,
however, that neither party shall be entitled to an award of punitive damages
pursuant to any arbitration proceeding undertaken pursuant to this Section. The
arbitrators shall have no power to add to, subtract from or modify any of the
terms or conditions of this Agreement.

     8.2  Notwithstanding Section 8.1, nothing in this Article shall be
construed to waive any rights of timely performance of any obligations existing
under this Agreement.

                 ARTICLE IX - PATENT ENFORCEMENT AND MAINTENANCE

     9.1  EVERGREEN shall maintain all patents of the Licensed Patents which
have Valid Claims, except as limited in Article 9.2, and shall have all access
and control of the patent files of the Licensed Patents at a law firm of
EVERGREEN's choosing.

     9.2  EVERGREEN shall have the option to waive rights to any of the Licensed
Patents, and shall provide three months prior written notice to SACHS if it does
not intend to maintain further any of such Licensed Patents, or of any such
maintenance fees, annual tax or other government fees which it does not intend
to timely pay, in order to allow SACHS to decide whether to make such payments
on his own behalf.

     9.3  In the event that either SACHS or EVERGREEN shall become informed of,
or have reason to believe that, any patent included in the Licensed Patents is
being infringed or potentially infringed by any unlicensed third-party, it shall
promptly notify the other party in writing.

     9.4  EVERGREEN shall have the right, but not the obligation, to (i) bring
suit or other necessary and appropriate legal action, including, without
limitation, counterclaims and cross-

                                      -11-
<PAGE>   12

claims (the "Infringement Action"), at EVERGREEN's own expense, joining SACHS as
a party if necessary or desirable, to terminate or prevent the infringement or
potential infringement of any patent included in the Licensed Patents, and (ii)
to negotiate with the alleged infringer (the "Infringement Negotiation") and to
effect such settlement consistent with the terms of this Agreement as EVERGREEN
may deem proper. All proceeds of any award, settlement or judgment resulting
from such Infringement Action or Infringement Negotiation (the "Recovery") shall
be divided between EVERGREEN and SACHS as follows: EVERGREEN shall receive the
aggregate amount of the Recovery, and shall pay to SACHS from such Recovery the
amount that is equal to the royalties, if any, that SACHS would have received
under this Agreement for sales of EVERGREEN products of similar type and in
equivalent amounts to the sales of the infringing or allegedly infringing
products from which the Recovery was derived. SACHS agrees to cooperate fully
with EVERGREEN in providing documentation, witnesses and any other assistance
reasonably required to bring about a favorable result with respect to any
Infringement Action or Infringement Negotiation, and shall be paid by EVERGREEN
for such cooperation at a rate equal to the consulting rate set forth in this
Agreement. SACHS shall be kept fully informed by EVERGREEN or its
representatives of all legal actions taken by EVERGREEN in connection with any
Infringement Action or Infringement Negotiation. SACHS may be represented at any
such legal proceedings by counsel selected and retained by SACHS at his sole
direction and expense.

     9.5  EVERGREEN shall defend, at EVERGREEN's own expense, except as provided
for in Article 6.1, and joining SACHS as a party if necessary or desirable, all
suits and legal actions arising from the use, development, manufacture, and sale
of the Technology; and EVERGREEN shall have the right to negotiate with the
opposing party, and to effect such settlement consistent with the terms of this
Agreement, as EVERGREEN may deem proper. SACHS agrees to cooperate fully with
EVERGREEN in providing documentation, witnesses and any other assistance
reasonably required to bring about a favorable result and shall be paid by
EVERGREEN for such cooperation at a rate equal to the consulting rate set forth
in this Agreement; and SACHS shall be kept fully informed by EVERGREEN or its
representatives of all such legal proceedings taken by EVERGREEN. SACHS may be
represented at such legal proceedings by counsel selected and retained by SACHS
at his sole direction and expense.

     9.6  EVERGREEN shall have the right, but not the obligation, to file
additional patent applications describing and claiming the Technology which
EVERGREEN, in its sole discretion shall deem reasonably necessary to protect its
rights, through an attorney of EVERGREEN's choosing, and in such event shall
assume the timely payment of any and all maintenance fees, annual taxes or other
government fees assessed as a condition of keeping such patent applications in
full force and effect. In the event that SACHS is an inventor on such patent
applications, EVERGREEN agrees to give SACHS three months prior written notice
if it does not intend to prosecute or maintain further any of such patent
applications, or of any such maintenance fees, annual tax or other government
fees which it does not intend to timely pay, in order to allow SACHS to decide
whether to make such payment on his own behalf.

                         ARTICLE X - GENERAL PROVISIONS

                                      -12-
<PAGE>   13

     10.1 The relationship of SACHS to EVERGREEN shall be that of an independent
contractor; SACHS shall not be considered to have the status of an agent or
employee under this Agreement, and shall not be entitled to participate in any
benefits provided by EVERGREEN to its employees. SACHS shall have no authority
to act for EVERGREEN or to bind it in any manner or thing, and shall not
represent to any person or business entity that he has such authority. Nothing
herein shall be construed to create any partnership, joint venture or similar
relationship, or to subject the parties to any implied duties or obligations
respecting the conduct of their affairs which are not expressly stated herein.

     10.2 EVERGREEN shall keep full accurate books of account containing all
particulars that may be necessary for the purpose of showing the royalties
payable to SACHS under this Agreement as aforesaid, including, without
limitation, records of the manufacture, sale and use of any Wafers, Cells,
Modules, Integrated Products or Other Products by Evergreen and any of its
sublicensees. The books and the supporting data shall be kept at EVERGREEN's
principal place of business, and the books and the supporting data shall be open
at a reasonable time, once per year, for three (3) years following the end of
the calendar year to which they pertain, to the inspection of SACHS and/or an
independent certified public accountant retained or employed by SACHS and
reasonably acceptable to EVERGREEN, for the purpose of verifying EVERGREEN's
royalty statement or compliance in other respects with this Agreement. Auditing
of EVERGREEN's books and supporting data by a representative of SACHS can occur
during normal business hours upon fourteen (14) days' written request. All fees
and expenses associated with any such audit shall be the sole responsibility of
SACHS, except that if the results of an audit show a discrepancy in favor of the
SACHS of more than five percent (5%) of the amount owed, all reasonable audit
costs shall be borne in full by EVERGREEN.

     10.3 SACHS acknowledges and understands that EVERGREEN may become engaged
in the development of additional products which may be competitive with Wafers,
Cells, Modules, Integrated Products and Other Products; that EVERGREEN shall not
be restricted in any manner from pursuing the development of such competitive
products; that SACHS shall have no right to receive any compensation or
royalties with respect to EVERGREEN's revenues therefrom, so long as the making,
use, and sale of such products do not fall within the scope of any of the Valid
Claims of the Licensed Patents.

     10.4 This Agreement shall be governed by and interpreted in accordance with
the laws of the Commonwealth of Massachusetts, exclusive of the choice of law
rules thereof, as if therein wholly to be performed, except that questions
affecting the construction and effect of any foreign patent shall be determined
by the law of the country in which the patent was granted. Nothing in this
Article shall preclude either party from seeking preliminary or temporary
injunctive relief from a court of competent jurisdiction.

     10.5 EVERGREEN may assign or otherwise transfer this Agreement, and the
license granted hereby and the rights and obligations acquired hereunder,
including, without limitation, such transfers caused (i) by operation of a
merger of EVERGREEN with another company, or (ii) by the sale or liquidation of
EVERGREEN's stock or assets, or (iii) by the transfer of an interest in this
Agreement pursuant to a security agreement delivered by EVERGREEN with respect
to

                                      -13-
<PAGE>   14

its rights under this Agreement, without the prior consent of SACHS, so long as
the assignee or transferee shall agree to the terms and conditions of this
Agreement.

     10.6 Notices or other communications provided for in this Agreement shall
be given in writing and shall be deemed effective on the date sent if sent to a
party hereto by personal delivery, certified or first class mail, postage
pre-paid, electronic facsimile transmission, or express overnight courier
service, addressed to the party at its address below (or at another address as
either party shall designate by written notice given to the other party):

          In the case of SACHS:
          Emanuel M. Sachs
          [CONFIDENTIAL TREATMENT REQUESTED]/*/
          [CONFIDENTIAL TREATMENT REQUESTED]/*/

          In the case of EVERGREEN:
          Evergreen Solar, Inc.
          76 Ten Hills Road
          Somerville, Massachusetts 02145

     10.7 The parties hereto acknowledge that this Agreement sets forth the
entire Agreement and understanding of the parties hereto as to the subject
matter hereof, and shall not be subject to any change or modification except by
the execution of a written instrument subscribed to by the parties hereto.

     10.8 The provisions of this Agreement are severable, and in the event that
any provision of this Agreement shall be determined to be invalid or
unenforceable under any controlling body of law, such invalidity or
unenforceability shall not in any way affect the validity or enforceability of
any remaining provisions hereof.

     10.9 In the event that any portion of this Agreement shall be reformed
under any controlling body of law, such reformation shall not affect any other
portion of the Agreement and the parties hereto agree to enforce all such other
portions to the maximum extent possible.

     10.10 The failure of either party to assert a right hereunder or to insist
upon compliance with any term or condition of this Agreement shall not
constitute a waiver of that right or excuse a similar subsequent failure to
perform any such term or condition by the other party.

     10.11 Until March 31, 1998, SACHS shall engage in no activity or ownership
which conflicts with any interest of EVERGREEN associated with the making, using
or selling of technology under the Licensed Patents. After March 31, 1998, for
the term of this Agreement, SACHS shall disclose to EVERGREEN, and EVERGREEN
shall have the option to license or purchase from SACHS, any intellectual
property rights owned by SACHS and related to the Licensed Patents or the
Technology but not covered by this Agreement, which option to license or
purchase shall be exercisable by EVERGREEN by written notice to SACHS within six
(6) months after EVERGREEN's receipt of notice of such intellectual property,
and shall be granted

/*/ [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

                                      -14-
<PAGE>   15

upon such reasonable terms and conditions as are determined by the parties
through good faith negotiations undertaken after EVERGREEN's exercise of the
option. The option granted to EVERGREEN pursuant to this Section shall be prior
and superior to any rights in such intellectual property held or claimed by any
party other than SACHS, and SACHS shall not sell, license, assign or otherwise
encumber such intellectual property rights to any party other than EVERGREEN
unless (i) EVERGREEN notifies SACHS in writing of its decision not to exercise
its option to such intellectual property rights or (ii) EVERGREEN does not elect
to exercise its option to the intellectual property rights within the six-month
exercise period described in the immediately preceding sentence.

     10.12 All products sold by EVERGREEN which encompass technology or
inventions covered by one or more of the Licensed Patents shall be marked with
the patent numbers of such Licensed Patents.

     10.13 (A) SACHS hereby covenants to (i) maintain all EVERGREEN Confidential
Information in confidence and not disclose same to any third party unless
expressly authorized in writing by EVERGREEN or required to do so by court order
or by law, in which case SACHS shall notify EVERGREEN in writing prior to making
such disclosure; (ii) not use any EVERGREEN Confidential Information for his own
benefit or for the benefit of any third party; and (iii) return all EVERGREEN
Confidential Information to EVERGREEN, including all copies, summaries and
extracts thereof, upon completion of assessment of the same for the purpose set
forth above, or upon termination of this Agreement, or sooner, if requested, and
shall, if requested by EVERGREEN, execute a certificate warranting that all such
Proprietary Information has been returned to EVERGREEN in accordance with this
Agreement.

           (B)  EVERGREEN hereby covenants to (i) maintain all SACHS
                Confidential Information in confidence and not disclose same to
                any third party unless expressly authorized in writing by SACHS
                or required to do so by court order or by law, in which case
                EVERGREEN shall notify SACHS in writing prior to making such
                disclosure; (ii) not use any SACHS Confidential Information for
                its own benefit or for the benefit of any third party; and (iii)
                return all SACHS Confidential Information to SACHS, including
                all copies, summaries and extracts thereof, upon completion of
                assessment of the same for the purpose set forth above, or upon
                termination of this Agreement, or sooner, if requested, and
                shall, if requested by SACHS, execute a certificate warranting
                that all such Proprietary Information has been returned to SACHS
                in accordance with this Agreement.

     10.14 The parties hereto shall comply in all respects with all applicable
laws.

                                      -15-
<PAGE>   16

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date first above written.

                                      EVERGREEN SOLAR, INC.

                                      BY: /s/ Mark Farber
                                         ------------------------------
                                          Mark Farber, President

                                      BY: /s/ Emanuel M. Sachs
                                         ------------------------------
                                          Emanuel M. Sachs

                                      -16-
<PAGE>   17

                                    EXHIBIT A

                                LICENSED PATENTS

     U.S. Patent No. 4,689,109, entitled "String Stabilized Ribbon Growth a
Method for Seeding Same," and any U.S. patent application, and foreign patents
and patent applications based thereon.

     U.S. Patent No. 4,661,200, entitled "String Stabilized ribbon Growth; Solar
Cell Substrates," and any U.S. patent application, and foreign patents and
patent applications based thereon.

     U.S. Patent No. 4,627,887, entitled "Melt Dumping in String Stabilized
Ribbon Growth; Crystallization," and any U.S. patent application, and foreign
patents and patent applications based thereon.

     U.S. Patent No. 4,594,229, entitled "Apparatus for Melt Growth of
Crystalline Semiconductor Sheets," and any U.S. patent application, and foreign
patents and patent applications based thereon.

     Great Britain Patent No. 2135595. (Lapsed)
     Great Britain Patent No. 2135594. (Lapsed)
     Great Britain Patent No. 2067920. (Lapsed)
     Japanese Patent No. 90036560. (Lapsed)
     French Patent No. 2473072. (Lapsed)
     German Patent No. 3100245. (Lapsed)
     Israeli Patent No. 61852.
     Canadian Patent No. 1169336.
     Italian Patent No. 1143254. (Lapsed)
     Japanese Patent No. 56125297. (Lapsed)

<PAGE>   18

                                    EXHIBIT B

                                Minimum Royalties
                                -----------------
<TABLE>
<CAPTION>
          Measurement Year                                      Minimum Royalty
          ----------------                                      ---------------

<S>                                                 <C>
[CONFIDENTIAL TREATMENT REQUESTED] /*/              [CONFIDENTIAL TREATMENT REQUESTED] /*/
[CONFIDENTIAL TREATMENT REQUESTED] /*/              [CONFIDENTIAL TREATMENT REQUESTED] /*/
[CONFIDENTIAL TREATMENT REQUESTED] /*/              [CONFIDENTIAL TREATMENT REQUESTED] /*/
[CONFIDENTIAL TREATMENT REQUESTED] /*/              [CONFIDENTIAL TREATMENT REQUESTED] /*/
[CONFIDENTIAL TREATMENT REQUESTED] /*/              [CONFIDENTIAL TREATMENT REQUESTED] /*/

</TABLE>

/*/ [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

<PAGE>   19

                                   EXHIBIT C

                                   (OMITTED)

<PAGE>   20

                                    EXHIBIT D

                            AGREEMENTS AND CONTRACTS

     1.   Agreement, dated March 1, 1980, between SACHS and Arthur D. Little,
Inc. ("Little"), as amended by a letter agreement dated November 20, 1987, and
termination letter from SACHS to Little, dated September 12, 1994.

     2.   Settlement Agreement, dated October 17, 1983, among Theodore F.
Ciszek, Jeffery L. Hurd, SACHS, Little and the United States Department of
Energy.

     3.   Agreement, dated July 8, 1985, between Solarex Corporation
("Solarex"), SACHS and Little, and termination letter from Solarex to Little and
SACHS, dated March 12,1986.

     4.   Contract no. XW-1-1069-1 and contract no. ZB-3-03009-1, each between
Little and the United States Department of Energy, and associated patent waiver
documents.

     5.   Memorandum of Agreement, dated June 6, 1977, between SACHS and Mobil
Tyco Solar Energy Corporation.

     6.   Treatment of Confidential Information, dated June 6, 1977, between
SACHS and Mobil Tyco Solar Energy Corporation.

     7.   Acknowledgment of obligations with respect to the treatment of
confidential information of Mobil Tyco Solar Energy Corporation, dated June 6,
1977, executed by SACHS.

     8.   Consultant's Agreement, dated August 1, 1979, between SACHS and Mobil
Tyco Solar Energy Corporation.

     9.   Consulting letter agreement, dated March 4, 1980, between SACHS and
Little, as renewed, amended and/or clarified by subsequent letter agreements
dated March 2, 1981, February 18, 1982, January 18, 1983, July 13, 1983, May 22,
1984, June 4, 1984, July 24, 1985, October 15, 1985, January 21, 1986 and
September 4, 1986.

<PAGE>   21

                                    EXHIBIT E
            SUMMARY OF MATERIAL DOCUMENTS, MEMORANDA AND INFORMATION

                                                                         Box # 1
                                                                         -------

                                  SACHS' FILES

<TABLE>
<CAPTION>
  File No.                          Description
  -------                           -----------

<S>            <C>
1.1            Interference: Dermatis background and negotiations.

1.2            Interference: Dermatis file wrapper.

1.3            Interference: Motions, decisions.

               Note: 1.1 and 1.2 discuss the Dermatis interference wherein
               Dermatis apparently in the end decided to drop any interference
               (besides the assertions that the two patents were substantially
               different, Dermatis was actually charged with fraud). 1.3 shows that
               Ciszek joined in what became a 3-way interference until Dermatis
               dropped out.

1.4            Interference: Prior art, patents and literature.

1.5            A NASA tech. brief - no label on this folder.

1.6            Interference:  Sachs proofs and tech. memos - contains a memo by Sachs on
                              the difference between ESR and web growth and an affidavit
                              by Prof. D. Adler that Sachs discussed this idea on or
                              before July 11, 1979.

1.7            Interference:  Declaration, correspondence, preliminary statement,
                              correspondence re: Dermatis and Ciszek interference.

1.8            Interference:  Sachs vs. Ciszek - some notes from Surek (includes notes re:
                              Surek's earlier conversations), a memo of the chronology.

1.9            Interference:  Motions, Sachs vs. Ciszek - Sachs suggests fraud because SERI
                              had confidential information on ESR before SERI filed.

1.10           Interference:  SERI, lit, etc. - excellent collection of Ciszek papers on edge
                              supported growth.

1.11           Interference:  Ciszek file wrapper.
</TABLE>

<PAGE>   22

<TABLE>
<CAPTION>

<S>            <C>
1.12           Interference:  Settlement includes copy of final settlement document with
                              signatures. Confidential memo from Surek to his superiors.
                              Contains a copy of EXHIBIT A in the settlement agreement.

1.13           Further notes on Ciszek interference.

1.14           General correspondence on the interference - letters from Pandiscio
               requesting copies of the interference (apparently initially denied), notes
               from Sachs' notebook, letter indicating the Ciszek interference is
               dissolved. Incomplete record of Mobil inquiry.

1.15           Exhibits for the Sachs-Ciszek interference - the original SERI REP, the
               ADL/SACHS PROPOSAL, copies of the Ciszek papers.

1.16           Ciszek vs. Sachs, Interference #100,758 - look like the original
               documents - Ciszek's oppositions to Sachs motions.

1.17           Ciszek vs. Sachs, Interference #100,758 - look like the original
               documents - Sachs Response to the oppositions of the Party Ciszek et
               al.

1.18           Application and progress reports from Sachs to Hertz Foundation in
               1979. Indicates Sachs' first PV research interest was bulk silicon
               slicing.

                                                                                             Box # 2
                                                                                             -------

2.1            Patent communications - background on patents in general and on film
               processor patent (not included in Evergreen license).

2.2            Sachs patents issued - copy of U.K. patent "String Stabilized Ribbon Growth
               of Crystals" - No. 2,067,920A.

2.3            Solar Patent #1 - Correspondence of the patent office in the basic patent
               No. 4,661,200 - original and copies of the patent letter explaining that
               Sachs is paying for this application himself, that he conceived of the
               idea in the summer of 1979, and that he was a graduate student under
               D. Adler and had to move his experiment to ADL where they had better
               facilities, etc.

2.4            Public laws and government regulations.

2.5            Bills - patent.

2.6            First solar patent search.
</TABLE>

<PAGE>   23

<TABLE>
<CAPTION>

<S>            <C>
2.7            Solar patents - performance value?

2.8            Melt dumping - original patents and data on this patent No. 4,627,887

2.9            Seeding patent - copy - not the original, No. 4,689,109.

2.10           Ciszek Patent - copy of this patent No. 4,594,229, issued 6/10/86.
               Assigned to E.M. Sachs.

2.11           Composite strings - patent application - initially rejected by the patent
               office and decided not to try further on it.

2.12           Diffusion length/laser scanner patent application - apparently rejected.

2.13           SERI/DOE - contains: listing of all patent information re: the
               government and patent status - including Mobil.

2.14           Miscellaneous.

                                                                                             Box # 3
                                                                                             -------

3.1            Presentation.

3.2            Contacts.

3.3            Licensing - business development efforts.

3.4            Licensing - much material on Toshiba interaction, including Toshiba
               option agreement that was never signed.

3.5            Graphics - many useful photos, original ADL brochure.

3.6            SERI - Year 1 - contains a useful report.

3.7            SERI - Year 2 (83) - RFP, proposal, contract.

3.8            SERI - Year 2 - reports to SERI.

3.9            SERI - Patent waiver - Year 2.

3.10           Business plan - ESR Inc.

3.11           SERI - 9/81 - 10/82, patent waiver Year 1.

3.12           SSG - Publicity.

3.13           SERI - 9/81 - 10/82, RFP, proposal, contract, correspondence.
</TABLE>

<PAGE>   24

<TABLE>
<CAPTION>

<S>            <C>
3.14           SERI - correspondence re: publications.

3.15           SERI - patent disclosures re: waiver - important disclosures, including
               storing materials, radiation shields.

3.16           Mislabeled: RFP's, proposals, SERI patent correspondence. Actually
               contains SBIR information for 1983 almost totally.

3.17           JPL Year 3 proposal - letter to Prince, DOE, telling of settling of the
               patent interference issue.

               Note: It is clear that Box 3 does not contain a complete record of the
               SERI patent waivers.
</TABLE>
<PAGE>   25

                       SOME KEY PERSONNEL IN SACHS' FILES

1.   TED CISZEK - Scientist at National Renewable Energy Lab (NREL) [Formerly
     called Solar Energy Research Institute - SERI].

2.   S. DERMATIS - Scientist originally at Westinghouse.

3.   TOM SUREK - Scientist/Manager at NREL for the past 16 years. Prior to that,
     was at Mobil-Tyco (this became Mobil-Solar) for several years.

4.   PROF. DAVID ADLER - Sachs' Ph.D. advisor at MIT.

5.   NICK PANDISCIO Mobil Solar's patent counsel.<PAGE>   1
                                                                    Exhibit 10.8

                  SERIES D PREFERRED STOCK PURCHASE AGREEMENT
                  -------------------------------------------

     This Agreement dated as of December 28, 1999 is entered into by and among
Evergreen Solar, Inc., a Delaware corporation (the "COMPANY"), the Purchasers
(the "PURCHASERS") and Prior Purchasers ("PRIOR PURCHASERS") whose names are
signed below listed on EXHIBIT A attached hereto, and, the Founders whose names
are signed below ("Founders").

     WHEREAS, the parties hereto desire to provide for the purchase and sale of
certain securities of the Company as set forth herein;

     NOW, THEREFORE, in consideration of the mutual promises and covenants
contained in this Agreement, the parties hereto agree as follows:

     1.   AUTHORIZATION AND SALE OF SHARES.

          (a)  Authorization. The Company has (a) duly authorized the sale and
issuance of up to 10,000,000 shares of its Series D Convertible Preferred Stock,
$.01 par value per share (the "Series D Preferred"), having the rights,
restrictions, privileges and preferences set forth in the Amended and Restated
Certificate of Incorporation attached hereto as Exhibit B (the "Amended
Certificate"). The Company has, or on or before the Closing (as defined in
Section 2) will have, adopted and filed with the Secretary of State of Delaware
an Amended and Restated Certificate of Incorporation in the form of the Amended
Certificate.

          (b)  SALE OF SHARES. Subject to the terms and conditions of this
Agreement, at the Closing (as defined in Section 2), the Company will sell and
issue to each of the Purchasers listed on EXHIBIT A attached hereto, and each of
the Purchasers listed on EXHIBIT A attached hereto will purchase, the number of
shares of Series D Preferred set forth opposite such Purchaser's name on EXHIBIT
A attached hereto for the purchase price of $2.50 per share in cash. The shares
of Series D Preferred being sold under this Agreement are referred to as the
"SHARES".

          (c)  SEPARATE AGREEMENTS. The Company's agreement with each of the
Purchasers is a separate agreement, and the sale of the Shares to each of the
Purchasers is a separate sale.

          (d)  USE OF PROCEEDS. The Company will use the proceeds from the sale
of the Shares for research and development of photovoltaic technology,
procurement of equipment, working capital and other general corporate purposes.

     2.   CLOSING. The closing of the initial sale and purchase of Shares (the
"Closing") is taking place simultaneously with the execution of this Agreement
at the offices of Testa, Hurwitz & Thibeault LLP in Boston, Massachusetts at
10:00 A.M. on December 28, 1999. At the Closing, the Company will deliver to
each of the Purchasers buying Shares a certificate for the

<PAGE>   2

number of Shares then being purchased by such Purchaser, registered in the name
of such Purchaser, against payment to the Company in U.S. dollars of the
purchase price therefor, by wire transfer, check, or other method acceptable to
the Company. The date of the Closing or any Subsequent Closing, as defined
below, is hereinafter referred to as the "CLOSING DATE". If at the Closing any
of the conditions specified in Section 5 shall not have been fulfilled, each of
the Purchasers shall, at his or its election, be relieved of all of his or its
obligations under this Agreement without thereby waiving any other rights he or
it may have by reason of such failure or such nonfulfillment. One or more
additional closings ("SUBSEQUENT CLOSINGS") under this Agreement may be held
prior to January 31, 2000 to provide for the sale of Shares to additional
parties (the "SUBSEQUENT PURCHASERS") reasonably acceptable to the Company and
its Board of Directors; provided, that the aggregate number of Shares sold
hereunder shall not exceed 10,000,000. Each Subsequent Purchaser shall become a
party to this Agreement upon execution and delivery of a counterpart of this
Agreement (and without the necessity for any amendment hereof other than the
supplementation of EXHIBIT C hereof to reflect the joinder of such Subsequent
Purchaser as a Purchaser hereunder) and shall thereafter be deemed to be a
Purchaser entitled to all of the rights and subject to all of the obligations of
a Purchaser in respect of the shares of Series D Preferred purchased by such
Subsequent Purchaser, which shares shall be deemed to be "Shares" hereunder.

     3.   REPRESENTATIONS AND WARRANTIES OF THE COMPANY. Subject to and except
as disclosed by the Company in EXHIBIT C attached hereto, the Company hereby
represents and warrants to each of the Purchasers as follows:

          (a)  ORGANIZATION AND STANDING. The Company is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware and has full corporate power and authority to conduct its business as
presently conducted and as proposed to be conducted by it, to enter into and
perform this Agreement, the transactions contemplated hereby and any other
agreement to which the Company is a party the execution of which is contemplated
hereby and to issue and sell the Shares and the Common Stock issuable upon
conversion thereof. The Company is duly qualified to do business as a foreign
corporation and is in good standing in the Commonwealth of Massachusetts and in
all other jurisdictions in which the failure to so qualify would have a material
adverse effect on its business, properties, prospects or financial condition.
The Company has furnished to the Purchasers true and complete copies of its
Certificate of Incorporation and By-Laws, each as amended to date and presently
in effect.

          (b)  CAPITALIZATION. The authorized capital stock of the Company
immediately prior to the Closing will consist of 28,000,000 shares of Common
Stock, $.01 par value per share ("COMMON STOCK"), of which 1,737,500 shares are
issued and outstanding, and 18,349,181 shares of Preferred Stock, $.01 par value
per share, 2,124,968 shares of which shall be designated as Series A Convertible
Preferred Stock ("SERIES A PREFERRED"), all of which are issued and outstanding,
2,78l,666 shares of which shall be designated as Series B Convertible Preferred

                                       2
<PAGE>   3

Stock ("SERIES B PREFERRED"), all of which are issued and outstanding, 3,442,547
shares of which shall be designated as Series C Convertible Preferred Stock
("SERIES C PREFERRED"), all of which are issued and outstanding, and 10,000,000
shares of which shall be designated as Series D Preferred, none of which shall
have been issued. All of the issued and outstanding shares of capital stock of
the Company have been duly authorized and validly issued and are fully paid and
nonassessable. Except as set forth in EXHIBIT B, C or D hereto or provided in
this Agreement, (i) no subscription, warrant, option, convertible security or
other right (contingent or otherwise) to purchase or acquire any shares of
capital stock of the Company is authorized or outstanding, (ii) there is not any
commitment of the Company to issue any subscription, warrant, option,
convertible security or other such right or to issue or distribute to holders of
any shares of its capital stock any evidences of indebtedness or assets of the
Company, and (iii) the Company has no obligation (contingent or otherwise) to
purchase, redeem or otherwise acquire any shares of its capital stock or any
interest therein or to pay any dividend or make any other distribution in
respect thereof. Except as provided in this Agreement, no person or entity is
entitled to (i) any preemptive or similar right with respect to the issuance of
any capital stock of the Company, or (ii) any rights with respect to the
registration of any capital stock of the Company under the Securities Act of
1933, as amended (the "SECURITIES ACT"). All of the issued and outstanding
shares of Common Stock have been offered, issued and sold by the Company in
compliance with applicable Federal and state securities laws. To the best of the
Company's knowledge, no stockholder of the Company has granted options or other
rights to purchase any shares of Common Stock from such stockholder.

          (c)  SUBSIDIARIES. The Company has no subsidiaries and does not own or
control, directly or indirectly, any other corporation, association or business
entity.

          (d)  STOCKHOLDER LIST AND AGREEMENTS. Attached as EXHIBIT D is a true
and complete list of the stockholders of the Company, showing the number of
shares of Common Stock or other securities of the Company held by each
stockholder as of the date of this Agreement. Except as contemplated by this
Agreement, there are no agreements, written or oral, between the Company and any
holder of its capital stock, or, to the best knowledge of the Company, among any
holders of its capital stock, relating to the acquisition, disposition or voting
of the capital stock of the Company.

          (e)  ISSUANCE OF SHARES. The issuance, sale and delivery of the Shares
and the issuance and delivery of the shares of Common Stock issuable upon
conversion of the Shares have been duly authorized and reserved for issuance, as
the case may be, by all necessary corporate action on the part of the Company,
and the Shares when so issued, sold and delivered against payment therefor in
accordance with the provisions of this Agreement, and the shares of Common Stock
issuable upon conversion of the Shares when issued upon such conversion, will be
duly and validly issued, fully paid and nonassessable.

          (f)  AUTHORITY FOR AGREEMENT. The execution, delivery and performance
by the

                                       3
<PAGE>   4

Company of this Agreement and the Fourth Amended and Restated Co-Sale Agreement
of even date herewith among the Company, the Founders, the Purchasers and the
Prior Purchasers (the "CO-SALE AGREEMENT") (this Agreement and the Co-Sale
Agreement are referred to herein as "AGREEMENTS") have been duly authorized by
all necessary corporate action, and each of the Agreements has been duly
executed and delivered by the Company. Each of the Agreements constitutes the
valid and binding obligation of the Company and the Founders enforceable in
accordance with its terms. The execution of the Agreements and performance of
the transactions contemplated thereby and compliance with their provisions by
the Company and the Founders will not violate any provision of law and will not
conflict with or result in any breach of any of the terms, conditions or
provisions of, or constitute a default under, the Company's Certificate of
Incorporation or By-Laws, each as amended to date and presently in effect, or
any indenture, lease, agreement or other instrument to which the Company or any
Founder is a party or by which the Company, any Founder or any of their
respective properties is bound, or any decree, judgment, order, statute, rule or
regulation applicable to the Company.

          (g)  GOVERNMENTAL CONSENTS. No consent, approval, order or
authorization of, or registration, qualification, designation, declaration or
filing with, any governmental authority is required on the part of the Company
in connection with the execution and delivery of the Agreements, the offer,
issue, sale and delivery of the Shares, or the other transactions to be
consummated at the Closing, except (i) requisite filings with appropriate state
securities authorities, which the Company hereby covenants to make on a timely
basis, and (ii) such filings as shall have been made prior to and shall be
effective on and as of the Closing. Based on the representations made by each of
the Purchasers in Section 4 of this Agreement, and the making of such filings,
the offer and sale of the Shares to each of the Purchasers will be in compliance
with applicable Federal and state securities laws and are exempt from the
registration requirements of the Securities Act of 1933, as amended.

          (h)  LITIGATION. There is no action, suit, proceeding or investigation
pending, or, to the best of the Company's knowledge, any basis therefor or
threat thereof, against the Company, or any of the Company's officers and
directors, which questions the validity of this Agreement or the right of the
Company to enter into any such agreement, or which might result, either
individually or in the aggregate, in any material adverse change in the assets,
condition (financial or otherwise), business or prospects of the Company.

          (i)  FINANCIAL STATEMENTS. The Company has furnished to each of the
Purchasers a complete and correct copy of the audited balance sheet of the
Company as of December 31, 1998 and the unaudited balance sheet of the Company
as at September 30, 1999 (such balance sheet is referred to herein as the
"BALANCE SHEET"; September 30, 1999 is referred to herein as the "BALANCE SHEET
DATE") and the related statements of operations and cash flows for the year
ended December 31, 1998 and the three months ended September 30, 1999
(collectively, the "FINANCIAL STATEMENTS"). The Financial Statements are
complete and correct in all material respects, are in accordance with the books
and records of the Company and present fairly the

                                       4
<PAGE>   5

financial condition and results of operations of the Company, as at the dates
and for the periods indicated, and have been prepared in accordance with
generally accepted accounting principles consistently applied, except that the
Financial Statements have been prepared for the internal use of management and
may not be in accordance with generally accepted accounting principles because
of the absence of footnotes normally contained therein and are subject to normal
year-end audit adjustments which in the aggregate will not be material.

          (j)  ABSENCE OF LIABILITIES. Except as disclosed in EXHIBIT C attached
hereto, the Company did not have, at the Balance Sheet Date, any liabilities of
any type which in the aggregate exceeded $25,000, whether absolute or
contingent, which were not fully reflected on the Balance Sheet, and, since the
Balance Sheet Date, the Company has not incurred or otherwise become subject to
any such liabilities or obligations except in the ordinary course of business.

          (k)  PROPERTY AND ASSETS. The Company has good title to all of its
material properties and assets, including all properties and assets reflected in
the Balance Sheet, except those disposed of since the date thereof in the
ordinary course of business, and none of such properties or assets is subject to
any mortgage, pledge, lien, security interest, lease, charge or encumbrance
other than those the material terms of which are described in the Balance Sheet
or in EXHIBIT C attached hereto.

          (l)  PATENTS AND TRADEMARKS. Set forth on EXHIBIT C attached hereto is
a true and complete list of all patents, patent applications, trademarks,
service marks, trademark and service mark applications, trade names, copyrights
and licenses presently owned or held by the Company. The Company owns or
possesses all of the patents, trademarks, service marks, trade names,
copyrights, proprietary rights, trade secrets, and licenses or rights to the
foregoing, necessary for the conduct of the Company's business as conducted and
as proposed to be conducted, including, without limitation, a license from
Emanuel Michael Sachs of the inventions covered by United States Patent Nos.
4,594,229, 4,661,200, 4,689,109 and 4,627,887, and all product concepts
described in the Business Plan of Evergreen (Series D Financing) (the "BUSINESS
PLAN"). To the best of the Company's knowledge, the business proposed by the
Company will not cause the Company to infringe or violate any of the patents,
trademarks, service marks, trade names, copyrights, licenses, trade secrets or
other proprietary rights of any other person or entity. The Company is not aware
that any employee is obligated under any contract (including any license,
covenant or commitment of any nature), or subject to any judgment, decree or
order of any court or administrative agency, that would interfere with the use
of such employee's best efforts to promote the interests of the Company or would
conflict with the Company's business as proposed to be conducted. To the best of
the Company's knowledge, no prior employer of any employee of the Company has
any right to or interest in any inventions, improvements, discoveries or other
information assigned to the Company by such employee pursuant to the
nondisclosure and assignment of invention agreement (in the form attached hereto
as EXHIBIT E) executed by such employee, or otherwise so assigned.

          (m)  INSURANCE. The Company maintains or will acquire within 60 days
after

                                       5
<PAGE>   6
the date hereof valid policies of workers' compensation insurance and of
insurance with respect to its properties and business of the kinds and in the
amounts not less than is customarily obtained by corporations of established
reputation engaged in the same or similar business and similarly situated,
including, without limitation, insurance against loss, damage, fire, theft,
public liability and other risks.

          (n)  MATERIAL CONTRACTS AND OBLIGATIONS. EXHIBIT C attached hereto
sets forth a list of all material agreements of any nature to which the Company
is a party or by which it is bound, including without limitation (i) each
agreement which requires future expenditures by the Company in excess of
$10,000, (ii) all employment and consulting agreements, employee benefit, bonus,
pension, profit-sharing, stock option, stock purchase and similar plans and
arrangements, and distributor and sales representative agreements, and (iii) any
agreement to which any stockholder, officer or director of the Company, or any
"affiliate" or "associate" of such persons (as such terms are defined in the
rules and regulations promulgated under the Securities Act), is presently a
party, including without limitation any agreement or other arrangement providing
for the furnishing of services by, rental of real or personal property from, or
otherwise requiring payments to, any such person or entity. The Company has
delivered to the Purchasers copies of such of the foregoing agreements as they
have requested. All of such agreements and contracts are valid, binding and in
full force and effect.

          (o)  COMPLIANCE. The Company has, in all material respects, complied
with all laws, regulations and orders applicable to its present and proposed
business and has all material permits and licenses required thereby. There is no
term or provision of any material mortgage, indenture, contract, agreement or
instrument to which the Company is a party or by which it is bound, or, to the
knowledge of the Company, of any provision of any state or Federal judgment,
decree, order, statute, rule or regulation applicable to or binding upon the
Company, which materially adversely affects or, so far as the Company may now
foresee, in the future is reasonably likely to materially adversely affect, the
business, prospects, condition, affairs or operations of the Company or any of
its properties or assets. To the best of the knowledge of the Company, none of
the employees of the Company is in violation of any term of any employment
contract, patent or other proprietary information disclosure agreement or any
other contract or agreement relating to the employment of such employee by the
Company.

          (p)  ABSENCE OF CHANGES. Except as set forth on EXHIBIT C attached
hereto, since the Balance Sheet Date, there has been no material adverse change
in the condition, financial or otherwise, net worth or results of operations of
the Company, other than changes occurring in the ordinary course of business
which changes have not, individually or in the aggregate, had a material adverse
effect on the business, prospects, properties or condition, financial or
otherwise, of the Company.

          (q)  EMPLOYEES. All employees, material consultants, or other
consultants of, or vendors to, the Company whose activities require access to
confidential or proprietary

                                       6
<PAGE>   7

information of the Company have executed and delivered nondisclosure,
noncompetition and assignment of invention agreements substantially in the form
of EXHIBIT E-1 or E-2 attached hereto, respectively, and all of such agreements
are in full force and effect. None of the employees of the Company is
represented by any labor union, and there is no labor strike or other labor
trouble pending with respect to the Company (including, without limitation, any
organizational drive) or, to the best knowledge of the Company, threatened.

          (r)  TAXES. The amount shown on the Balance Sheet as provision for
taxes is sufficient in all material respects for payment of all accrued and
unpaid Federal, state, county, local and foreign taxes for the period then ended
and all prior periods. The Company has filed or has obtained presently effective
extensions with respect to all Federal, state, county, local and foreign tax
returns which are required to be filed by it, such returns are true and correct
and all taxes shown thereon to be due have been timely paid with exceptions not
material to the Company. Federal income tax returns of the Company have not been
audited by the Internal Revenue Service, and no controversy with respect to
taxes of any type is pending or, to the best of the Company's knowledge,
threatened. Neither the Company nor any of its stockholders has ever filed (a)
an election pursuant to Section 1362 of the Internal Revenue Code of 1986, as
amended (the "Code"), that the Company be taxed as an S Corporation or (b)
consent pursuant to Section 341(f) of the Code relating to collapsible
corporations.

          (s)  SMALL BUSINESS CONCERN. The Company is a "small business concern"
as defined in Section 121.802 of Title 13 of the Code of Federal Regulations.

          (t)  U.S. REAL PROPERTY HOLDING CORPORATION. The Company is not now
and has never been a "United States Real Property Holding Corporation" as
defined in Section 897(c)(2) of the Code and Section 1.897-2(b) of the
Regulations promulgated by the Internal Revenue Service.

          (u)  BOOKS AND RECORDS. The minute books of the Company contain
complete and accurate records of all meetings and other corporate actions of its
stockholders and its Board of Directors and committees thereof. The stock ledger
of the Company is complete and reflects all issuances, transfers, repurchases
and cancellations of shares of capital stock of the Company.

          (v)  RELATED PARTIES. No employee, officer, stockholder or director of
the Company or member of his or her immediate family is indebted to the Company,
nor is the Company indebted (or committed to make loans or extend or guarantee
credit) to any of them, other than (i) for payment of salary for services
rendered, (ii) reimbursement for reasonable expenses incurred on behalf of the
Company and (iii) for other standard employee benefits made generally available
to all employees (including stock option agreements outstanding under any stock
option plan approved by the Board of Directors of the Company).

          (w)  DISCLOSURES. Neither this Agreement nor any Exhibit hereto, nor
any

                                       7
<PAGE>   8

report, certificate, statement or instrument supplied by the Company to any of
the Purchasers or their counsel in connection with the transactions contemplated
by this Agreement, when read together, contains or will contain any material
misstatement of fact or omits or will omit to state a material fact necessary to
make the statements contained herein or therein not misleading. The Company
knows of no information or fact which has or would have a material adverse
effect on the financial condition, Business or prospects of the Company which
has not been disclosed in writing to the purchasers. The Company has no reason
to believe that the projections and estimates of market size set forth in the
Business Plan do not represent reasonable estimates based on the assumptions
contained therein, but there can be no assurance that the results reflected in
such projections will be attained.

     4.   REPRESENTATIONS OF THE PURCHASERS. Each of the Purchasers severally
represents and warrants to the Company as follows:

          (a)  INVESTMENT. Such Purchaser is acquiring the Shares and the shares
of Common Stock into which the Shares may be converted for his or its own
account for investment and not with a view to, or for sale in connection with,
any distribution thereof, nor with any present intention of distributing or
selling the same; and, except as contemplated by this Agreement and the Exhibits
hereto, and such Purchaser has no present or contemplated agreement,
undertaking, arrangement, obligation, indebtedness or commitment providing for
the disposition thereof.

          (b)  AUTHORITY. Such Purchaser has full power and authority to enter
into and to perform this Agreement in accordance with its terms. Any Purchaser
which is a corporation, partnership, trust or other entity represents that it
has not been organized, reorganized or recapitalized specifically for the
purpose of investing in the Company, or, if it has been organized specifically
for the purpose of investing in the Company, all of the equity owners of such
corporation, partnership, trust or other entity are accredited investors within
the definition set forth in Securities Act Rule 501(a).

          (c)  EXPERIENCE. Such Purchaser has carefully reviewed the
representations concerning the Company contained in this Agreement, and has made
detailed inquiry concerning the Company, its business and its personnel; the
officers of the Company have made available to such purchaser any and all
written information which he or it has requested and have answered to such
purchaser's satisfaction all inquiries made by such purchaser; such Purchaser
has adequate net worth and means of providing for his or its current needs and
personal contingencies to sustain a complete loss of his or its investment in
the Company; such Purchaser's overall commitment to investments which are not
readily marketable is not disproportionate to his or its net worth; and such
Purchaser's investment in the Shares will not cause such overall commitment to
become excessive.

          (d)  ACCREDITED INVESTOR. Such purchaser is an accredited investor
within the

                                       8
<PAGE>   9

 definition set forth in Securities Act Rule 501(a).

     5.   CONDITIONS TO THE OBLIGATIONS OF THE PURCHASERS. The obligation of
each of the Purchasers to purchase Shares at the Closing or any Subsequent
Closing is subject to the fulfillment, or the waiver by such Purchaser, of the
following conditions on or before the applicable Closing Date:

          (a)  ACCURACY OF REPRESENTATIONS AND WARRANTIES. The representations
and warranties contained in Section 3 of this Agreement shall be true on and as
of the Closing Date with the same effect as though such representations and
warranties had been made on and as of that date; provided, that the
representations contained in the first sentence of Section 3(b) and the first
sentence of 3(d) shall be updated as of any Subsequent Closing.

          (b)  PERFORMANCE. The Company shall have performed and complied with
all agreements and conditions contained in this Agreement required to be
performed or complied with by the Company prior to or at the Closing or
Subsequent Closing.

          (c)  OPINION OF COUNSEL. The purchasers shall have received an opinion
from Testa, Hurwitz & Thibeault, LLP, counsel for the Company, dated the Closing
Date, addressed to the purchasers, to the effect that:

               (i)  The Company is a corporation duly organized, validly
existing and in good standing under the laws of the State of Delaware and has
full corporate power and authority to conduct its business as presently
conducted, to enter into and perform each of the Agreements and to carry out the
transactions contemplated by each of the Agreements. The Company is duly
qualified to do business as a foreign corporation and is in good standing in the
Commonwealth of Massachusetts.

               (ii) Except for changes contemplated by this Agreement, the
authorized capital stock of the Company is as described in subsection 3(b) of
this Agreement and, to the knowledge of such counsel, the other representations
and warranties contained in subsection 3(b) are true and correct (other than the
last sentence thereof, as to which no opinion need be expressed, and other than
the next to last sentence thereof, as to which an opinion need only be expressed
that no registration was required for the offer, issuance and sale of the Common
Stock referred to therein under applicable Federal and state securities laws).

               (iii) The issuance, sale and delivery of the Shares by the
Company and the issuance and delivery of the shares of Common Stock issuable
upon conversion of the Shares have been duly authorized and reserved for
issuance, as the case may be, by all necessary corporate action on the part of
the Company, and the Shares when so issued, sold and delivered against payment
therefor in accordance with the provisions of this Agreement and the shares of
Common Stock issuable upon conversion of the Shares, when

                                       9
<PAGE>   10

issued upon such conversion, will be duly and validly issued, fully paid and
nonassessable.

               (iv) The execution, delivery and performance by the Company of
each of the Agreements have been duly authorized by all necessary corporate
action, and each of the Agreements has been duly executed and delivered by the
Company. Each of the Agreements (other than subsections 8(g) and 8(h) hereof, as
to which no opinion need be expressed) constitutes the valid and binding
obligation of the Company and of the Founders (assuming legal capacity of the
Founders), enforceable in accordance with its terms, subject as to enforcement
of remedies to applicable bankruptcy, insolvency, reorganization or similar laws
affecting generally the enforcement of creditors' rights and subject to a
court's discretionary authority with respect to the granting of a decree
ordering specific performance or other equitable remedies. The execution and
delivery of each of the Agreements and the offer, issue and sale of the Shares
hereunder will not conflict with, or result in any breach of any of the terms,
conditions, or provisions of, or constitute a default under, the Certificate of
Incorporation or By-Laws of the Company, each as amended to date and presently
in effect, or any indenture, lease, agreement, or other instrument known to such
counsel to which the Company is a party or by which it or any of its properties
are bound, or any decree, judgment or order specifically naming the Company and
known to such counsel.

               (v)  Except as obtained and in effect at the Closing or
Subsequent Closing, no consent, approval, order or authorization of, or
registration, qualification, designation, declaration, or filing with, any
governmental authority (other than filings required to be made after such
Closing under applicable federal and state securities laws) is required on the
part of the Company in connection with the execution and delivery of the
Agreements, or the offer, issue, sale and delivery of the Shares or the other
transactions to be consummated at such Closing pursuant to this Agreement.

               (vi) Based on the representations of each of the Purchasers in
Section 4, the offer, issuance and sale of the Shares and the shares of Common
Stock issuable upon conversion of the Shares are exempt from registration under
the Securities Act.

               (vii) To the best of such counsel's knowledge, except as set
forth in EXHIBIT C to this Agreement, there is no action, suit or proceeding, or
governmental inquiry or investigation, pending or threatened against the
Company.

          (d)  BLUE SKY APPROVALS. The Company shall have received any requisite
approvals and made any requisite filings with the securities commissioners of
Maryland, Massachusetts, California and any other states in which Purchasers are
located and any such approvals shall be in full force and effect on the
applicable Closing Date (other than filings required to be made after such
Closing Date).

                                       10
<PAGE>   11

          (e)  CERTIFICATES AND DOCUMENTS. The Company shall have delivered to
the Purchasers:

               (i)  The Certificate of Incorporation of the Company, as amended
and in effect prior to the Closing Date, certified by the Secretary of State of
the State of Delaware;

               (ii) Certificates, as of the most recent practicable dates, as to
the corporate good standing of the Company issued by the Secretary of State of
the State of Delaware, confirming such good standing on or immediately prior to
the Closing Date;

               (iii) By-laws of the Company as amended and in effect immediately
prior to the Closing Date, certified by its Secretary or Assistant Secretary as
of the Closing Date; and

               (iv) Resolutions of the Board of Directors and consents of the
stockholders of the Company, authorizing and approving all requisite matters in
connection with this Agreement, and the transactions contemplated hereby,
certified by the Secretary or Assistant Secretary of the Company as of the
Closing Date.

          (f)  BOARD OF DIRECTORS. Immediately after the Closing, the Board of
Directors of the Company shall consist of Mark A. Farber, Robert W. Shaw, Jr.
(who shall be Chairman of the Board), Richard G. Chleboski, Gordon Baty, William
C. Osborn, Mason Willrich, Brown F. Williams and William P. Sommers and the
provisions of Section C.3. of Article Fourth of the Amended Certificate shall
control the election of directors of the Company. No amendment shall be made to
the provisions of Section C.3. of Article Fourth of the Amended Certificate (as
the same may be amended from time to time), without the prior written consent of
UVCC Fund II, UVCC II Parallel Fund, L.P. and Nth Power Technologies Fund I,
L.P.

          (g)  CO-SALE AGREEMENT. The Co-Sale Agreement in the form attached
hereto as EXHIBIT G shall have been executed and delivered by the parties
thereto.

          (h)  MINIMUM INVESTMENT. The Purchasers shall have tendered at the
Closing aggregate consideration of not less than $10,000,000 for the purchase of
Shares.

          (i)  OTHER MATTERS. All corporate and other proceedings in connection
with the transactions contemplated by this Agreement and all documents and
instruments incident to such transactions shall be reasonably satisfactory in
substance and form to the Purchasers, and the Purchasers shall have received all
such counterpart originals or certified or other copies of such documents as
they may reasonably request.

     6.   CONDITIONS TO THE OBLIGATIONS OF THE COMPANY. The obligations of the
Company

                                       11
<PAGE>   12

under subsection 1(b) of this Agreement are subject to fulfillment, on or before
the Closing Date, of each of the following conditions:

          (a)  ACCURACY OF REPRESENTATIONS AND WARRANTIES. The representations
and warranties of the Purchasers contained in Section 4 shall be true on and as
of the Closing Date with the same effect as though such representations and
warranties had been made on and as of that date.

          (b)  BLUE SKY APPROVALS. The Company shall have received any requisite
approvals of the securities commissioner of any state in which a Purchaser is
located.

     7.   COVENANTS.

          (a)  INSPECTION; BOARD MEMBER EXPENSES. The Company shall permit each
Purchaser (treating any group of affiliated Purchasers as one Purchaser) who
buys more than $1,500,000 of Series D Preferred, or any authorized
representative thereof, to attend, as observers and without the right to vote
(except to the extent any such representative is a Board member), meetings of
the Board of Directors of the Company, to visit and inspect the properties of
the Company, including its corporate and financial records, and to discuss its
business and finances with officers of the Company, during normal business hours
following reasonable notice and as often as may be reasonably requested, and to
receive copies of all notices, minutes, consents and other materials that the
Company provides to its directors. The Board of Directors shall have the right
in its sole discretion to conduct any Board meeting or portion thereof in
executive session without observers present. The Company shall pay the
reasonable out-of-pocket expenses, including travel and lodging expenses,
associated with Board meeting attendance of all directors who are not employees
of the Company.

          (b)  FINANCIAL STATEMENTS AND OTHER INFORMATION.

               (i)  The Company will deliver to each Purchaser and each Prior
Purchaser:

                    (A)  within 90 days after the end of each fiscal year of the
Company, an audited balance sheet of the Company as at the end of such year and
audited statements of income and of changes in financial condition of the
Company for such year, examined or reviewed, at the option of the Board of
Directors of the Company, by certified public accountants selected by the
Company, all of such documents to be prepared in accordance with generally
accepted accounting principles;

                    (B)  within 45 days after the end of each fiscal quarter of
the Company, an unaudited balance sheet of the Company as at the end of such
quarter, and unaudited statements of income and of changes in financial
condition of the Company for such

                                       12
<PAGE>   13

fiscal quarter and for the current fiscal year to the end of such fiscal
quarter;

                    (C)  within 30 days after the end of each month, an
unaudited balance sheet of the Company as at the end of such month and unaudited
statements of income and of changes in financial condition of the Company for
such month and for the current fiscal year to the end of such month, setting
forth in comparative form the Company's projected financial statements for the
corresponding periods for the current fiscal year and including an aging of the
Company's accounts receivable and accounts payable and a statement of the number
of employees of the Company as at the end of such month;

                    (D)  as soon as available, but in any event within 30 days
after commencement of each new fiscal year, a Business Plan and projected
financial statements for such fiscal year and projected financial statements for
the four years following such new fiscal year; and

                    (E)  with reasonable promptness, such other notices,
information and data with respect to the Company as the Company delivers to the
holders of its Common Stock, and such other information and data as such
Purchaser or Prior Purchaser may from time to time reasonably request.

               (ii) The foregoing financial statements shall be prepared on a
consolidated basis if the Company then has any subsidiaries. The financial
statements delivered pursuant to clauses (B) and (C) of paragraph (i) shall be
accompanied by a certificate of the chief financial officer of the Company
stating that such statements have been prepared in accordance with generally
accepted accounting principles consistently applied (except as noted) and fairly
present the financial condition of the Company at the date thereof and for the
periods covered thereby.

          (c)  MATERIAL CHANGES AND LITIGATION. The Company will promptly notify
the Purchasers and Prior Purchasers of any material adverse change in the
business, properties, assets or condition, financial or otherwise, of the
Company and of any litigation or governmental proceeding or investigation
pending or, to the best knowledge of the Company, threatened against the
Company, or against any officer, director, key employee or principal stockholder
of the Company materially affecting or which, if adversely determined, would
materially adversely affect its present or proposed business, properties, assets
or condition taken as a whole.

          (d)  KEY MAN INSURANCE. Through December 31, 2000, the Company shall
maintain term life insurance upon the life of each of the Founders in the amount
of $500,000 each, with the proceeds payable to the Company. A certificate
evidencing such insurance shall be attached to this Agreement as EXHIBIT F.

          (e)  NONDISCLOSURE AGREEMENTS. The Company will require all persons
now or

                                       13
<PAGE>   14

hereafter employed by the Company who have access to confidential and
proprietary information of the Company to enter into agreements containing (i)
nondisclosure and assignment of invention provisions substantially similar to
those set forth in EXHIBIT E, and, subject to the discretion of the Board of
Directors of the Company, noncompetition provisions substantially similar to
those set forth in EXHIBIT E.

          (f)  RIGHT OF FIRST REFUSAL.

               (i)  The Company hereby grants to each Purchaser, each Prior
Purchaser and each Founder (collectively, the "RIGHTHOLDERS") a right of first
refusal to purchase, on a pro rata basis, all or any part of New Securities (as
defined below) which the Company may, from time to time, propose to sell and
issue, subject to the terms and conditions set forth below. A Rightholder's pro
rata share, for purposes of this subsection 7(f), shall equal a fraction, the
numerator of which is the number of shares of capital stock of the Company owned
by such Rightholder and the denominator of which is the total number of shares
of capital stock of the Company owned by all of the Rightholders.

               (ii) "NEW SECURITIES" shall mean any capital stock of the Company
whether now authorized or not, and rights, options or warrants to purchase
capital stock, and securities of any type whatsoever which are, or may become,
convertible into capital stock; PROVIDED, HOWEVER, that the term "New
Securities" does not include (A) the Shares issuable under this Agreement
(including any amendment hereto) or the shares of Common Stock issuable upon
conversion of the Series A Preferred, Series B Preferred, Series C Preferred or
Series D Preferred; (B) securities offered to the public pursuant to a
Registration Statement (as defined in subsection 8(a)); (C) securities issued
for the acquisition of another corporation by the Company by merger, purchase of
substantially all the assets of such corporation or other reorganization
resulting in the ownership by the Company of not less than 51% of the voting
power of such corporation; (D) shares of Common Stock issued to employees or
consultants of the Company pursuant to the Company's 1994 Stock Option Plan, as
amended, in an amount not in excess of the Plan Pool, as defined below; (E)
securities issued upon the exercise of currently outstanding warrants issued by
the Company; or (F) securities issued as a result of any stock split, stock
dividend or reclassification of Common Stock, distributable on a pro rata basis
to all holders of Common Stock. As used herein, the term "Plan Pool" means a
number of shares of Common Stock, as adjusted for stock splits, stock dividends
and similar recapitalizations, equal to the sum of (1) 1,175,000 shares plus (2)
the greater of (x) 1,500,000 shares or (y) 20% of the aggregate number of shares
of Series D Preferred sold hereunder.

               (iii) In the event the Company intends to issue New Securities,
it shall give each Rightholder written notice of such intention, describing the
type of New Securities to be issued, the price thereof and the general terms
upon which the Company proposes to effect such issuance. Each Rightholder shall
have 30 days from the date of any such notice to agree to purchase all or part
of its or his pro rata share of such New Securities for the price and upon the

                                       14
<PAGE>   15

general terms and conditions specified in the Company's notice by giving written
notice to the Company stating the quantity of New Securities to be so purchased.
Each Rightholder shall have a right of overallotment such that if any
Rightholder fails to exercise his or its right hereunder to purchase his or its
total pro rata portion of New Securities, the other Rightholders may purchase
such portion on a pro rata basis, by giving written notice to the Company within
five days from the date that the Company provides written notice to the other
Rightholders of the amount of New Securities with respect to which such
nonpurchasing Rightholder has failed to exercise its or his right hereunder.

               (iv) In the event any Rightholder fails to exercise the foregoing
right of first refusal with respect to any New Securities within such 30-day
period (or the additional five-day period provided for overallotments), the
Company may within 120 days thereafter sell any or all of such New Securities
not agreed to be purchased by the Rightholders, at a price and upon general
terms no more favorable to the purchasers thereof than specified in the notice
given to each Rightholder pursuant to paragraph (c) above. In the event the
Company has not sold such New Securities within such 120-day period, the Company
shall not thereafter issue or sell any New Securities without first offering
such New Securities to the Rightholders in the manner provided above.

               (v)  For purposes of this subsection 7(f), "Rightholder" shall
include the general partners, officers or other affiliates of a Purchaser, and a
Purchaser may apportion its pro rata share among itself and such general
partners, officers and other affiliates in such proportions as it deems
appropriate; provided that the pro rata share ownership of a Rightholder shall
be determined solely on the basis of the number of shares of capital stock of
the Company owned by such Rightholder and shall not be increased by the share
holdings of any affiliate of such Rightholder.

          (g)  NEGATIVE COVENANTS. Notwithstanding any other provision of this
Agreement, without (i) the prior written consent of the holders of at least 60%
of the outstanding shares of Preferred Stock, or (ii) solely with respect to
clauses (v), (vi) and (viii) below, the approval at a duly held Board meeting of
directors and/or observers representing the holders of at least 60% of the
outstanding shares of Preferred Stock, the Company shall not, nor shall any of
the Founders cause the Company to:

               (i)  merge or consolidate with any other corporation or purchase
or own any stock or other securities of or interest in any other corporation,
partnership or other entity (other than U.S. government or U.S.
government-backed securities purchased by the Company pending expenditure of
cash) or, except in the ordinary course of business, sell, lease, license or
otherwise dispose of any portion of its properties or assets to any party,
including without limitation any intellectual property;

               (ii) effect any reverse stock split, stock combination,
reclassification or

                                       15
<PAGE>   16

similar event;

               (iii) amend or repeal its Certificate of Incorporation or
By-Laws;

               (iv) except as permitted under this Agreement, the Certificate of
Incorporation or any agreement contemplated hereby, authorize, create, issue,
reclassify, repurchase or redeem any stock or other security of the Company, or
issue, grant, or, authorize any option, warrant or other right respecting any
stock or other security of the Company, provided, that such consent shall not be
required for the issuance of any option or right under the Company's 1994 Stock
Option Plan, as amended, or any other stock option or stock purchase plan duly
established by the Company, or for the purchase of any Common Stock upon the
exercise of an option or right issued under such a plan;

               (v)  make any loan or advance, other than trade credit on terms
approved by two-thirds (2/3) of the Board of Directors or partial payments on
capital expenditures approved by two-thirds (2/3) of the Board of Directors, to
any person or entity except for advances and similar expenditures in an
outstanding amount not to exceed $25,000 in the aggregate at any time;

               (vi) enter into any marketing, distribution, sales or other
"corporate partnering" agreement or plan which grants a third party exclusive or
substantial rights to market, sell, supply or manufacture the Company's products
or services; or, except as approved by a majority of the Board of Directors of
the Company, purchase, lease, license or otherwise acquire from others any
tangible or intangible property other than in the ordinary course of business;

               (vii) dissolve, liquidate or suspend all or any part of its
business, or file any petition, or institute any proceeding, or be subject to
any petition or proceeding filed against it that is not dismissed within thirty
(30) days after filing, under the Federal Bankruptcy Code or under any state law
relating to insolvency, receivership, reorganization or debt adjustment;

               (viii) have outstanding trade payables in an amount in excess of
$1,500,000, have outstanding trade payables more than 90 days old in an amount
in excess of $250,000, or incur, create, assume or otherwise become primarily or
secondarily liable with respect to, or absolutely or contingently liable with
respect to, or permit to exist, any other indebtedness, including without
limitation lease financing, which is in an aggregate amount in excess of
$250,000; provided that such consent or approval shall be required for any lease
which calls for aggregate payments in excess of $250,000 and for any guaranty of
indebtedness by the Company, regardless of amount;

               (ix) establish or modify any stock option or stock purchase plan
of the Company; or

                                       16
<PAGE>   17

               (x)  increase or decrease the authorized number of directors
constituting the Board of Directors.

     While it is not the desire of the Purchasers or Prior Purchasers to direct
the day-to-day management of the Company's affairs, the Purchasers and Prior
Purchasers are making a substantial investment in the Company and have a
justified interest in ensuring consensus with respect to the conduct of all
material aspects of the Company's business. The covenants set forth in this
subsection are not intended to impede actions by the Board of Directors in the
ordinary course of business so long as such actions are not likely to have a
material adverse impact on the Purchasers or Prior Purchasers. Each Purchaser
and Prior Purchaser shall respond promptly and, in any event, within 15 days to
any request for a consent under this subsection. The Company may in its
discretion in connection with requests for consent to any transaction pursuant
to this Subsection, (i) describe such transaction by means of a summary of the
terms thereof rather than by providing copies of applicable contracts and (ii)
withhold the name or names of the other party or parties to the transaction.

          (h)  INTERNATIONAL INVESTMENT AND TRADE IN SERVICES SURVEY ACT. The
Company shall use its best efforts to file on a timely basis all reports
required to be filed by it under 22 U.S.C. Section 3104, or any similar statute,
relating to a foreign person's direct or indirect investment in the Company.

          (i)  QUALIFIED SMALL BUSINESS STOCK. The Company shall submit to its
stockholders (including the Purchasers and Prior Purchasers) and to the Internal
Revenue Service any reports that may be required under Section 1202(d)(1)(C) of
the Code and the Regulations promulgated thereunder. In addition, within ten
business days after any Purchaser's or Prior Purchaser's written request
therefor, the Company shall deliver to such Purchaser or Prior Purchaser a
written statement indicating whether such Purchaser's or Prior Purchaser's
interest in the Company constitutes "qualified small business stock" as defined
in Section 1202(c) of the Code.

          (j)  SMALL BUSINESS. The Company shall submit such reports and provide
such assistance as may reasonably be required by any Purchaser or Prior
Purchaser which is a "small business investment company" under the Small
Business Investment Act of 1958 and the Regulations promulgated thereunder.

          (k)  TERMINATION OF COVENANTS. Unless earlier terminated, the
covenants contained in this Section 7 shall terminate, and be of no further
force or effect, upon the effectiveness of a Registration Statement (as defined
in subsection 8(a) covering the Company's first bona fide firm commitment public
offering of Common Stock, resulting in gross proceeds to the Company of at least
$25,000,000, at a price per share of at least $10.00 (as adjusted for stock
splits, stock dividends, recapitalizations and similar events).

                                       17
<PAGE>   18

     8.   REGISTRATION RIGHTS.

          (a)  CERTAIN DEFINITIONS. As used in this Section 8 and elsewhere in
this Agreement, the following terms shall have the following respective
meanings:

               "COMMISSION" means the Securities and Exchange Commission, or any
other Federal agency at the time administering the Securities Act.

               "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended, or any similar Federal statute, and the rules and regulations of the
Commission issued under such Act, as they each may, from time to time, be in
effect.

               "REGISTRATION STATEMENT" means a registration statement filed by
the Company with the Commission for a public offering and sale of Securities of
the Company (other than a registration statement on Form S-8 or Form S-4, or
their successors, or any other form for a limited purpose, or any registration
statement covering only Securities proposed to be issued in exchange for
Securities or assets of another corporation).

               "REGISTRATION EXPENSES" means the expenses described in
subsection 8(f).

               "REGISTRABLE SHARES" means (i) the shares of Common Stock issued
or issuable upon conversion of the Preferred Stock, (ii) shares of Common Stock
issued or issuable upon the exercise of currently outstanding warrants issued by
the Company, (iii) any shares of Common Stock of the Company acquired by the
Purchasers or Prior Purchasers pursuant to subsection 7(f) hereof, and (iv) any
other shares of Common Stock of the Company issued in respect of such shares
(because of stock splits, stock dividends, reclassifications, recapitalizations,
or similar events); PROVIDED, HOWEVER, that shares of Common Stock which are
Registrable Shares shall cease to be Registrable Shares upon any sale pursuant
to a Registration Statement, Section 4(1) of the Securities Act or Rule 144
under the Securities Act, or any sale in any manner to a person or entity which,
by virtue of Section 10 of this Agreement, is not entitled to the rights
provided by this Section 8. Wherever reference is made in this Agreement to a
request or consent of holders of a certain percentage of Registrable Shares, the
determination of such percentage shall include shares of Common Stock issuable
upon conversion of the Shares even if such conversion has not yet been effected.

               "SECURITIES ACT" means the Securities Act of 1933, as amended, or
any similar Federal statute, and the rules and regulations of the Commission
issued under such Act, as they each may, from time to time, be in effect.

               "SHARES" shall have the meaning specified in subsection 1(b).

                                       18
<PAGE>   19

               "STOCKHOLDERS" means the Purchasers and Prior Purchasers and any
persons or entities to whom the rights granted under this Section 8 are
transferred by any Purchasers or Prior Purchasers or their respective successors
or assigns pursuant to Section 10 hereof.

          (b)  SALE OR TRANSFER OF SHARES; LEGEND.

               (i)  The Shares and the Registrable Shares and shares issued in
respect of the Shares or the Registrable Shares shall not be sold or transferred
unless either (A) they first shall have been registered under the Securities
Act, or (B) the Company first shall have been furnished with an opinion of legal
counsel, reasonably satisfactory to the Company, to the effect that such sale or
transfer is exempt from the registration requirements of the Securities Act.

               (ii) Notwithstanding the foregoing, no registration or opinion of
counsel shall be required for a transfer by a Purchaser or Prior Purchaser to
any person or entity which directly or indirectly holds an interest in the
Purchaser or Prior Purchaser or a partner of any purchaser, or in connection
with a bona fide reorganization, if the transferee agrees in writing to be
subject to the terms of this Section 8 to the same extent as if he were an
original Purchaser or Prior Purchaser hereunder.

               (iii) Each certificate or other instrument representing the
Shares and the Registrable Shares and shares issued in respect of the Shares or
the Registrable Shares shall bear a legend substantially in the following form:

          "The Securities represented by this instrument have not been
     registered under the Securities Act of 1933, as amended, and may not be
     offered, sold or otherwise transferred, pledged or hypothecated unless and
     until such shares are registered under such Act or an opinion of counsel
     satisfactory to the Company is obtained to the effect that such
     registration is not required."

     The foregoing legend shall be removed from the certificates representing
any Registrable Shares, at the request of the holder thereof, at such time as
they become eligible for resale pursuant to Rule 144(k) under the Securities
Act.

               (iv) The Company shall, at all times during which it is neither
subject to the reporting requirements of Section 13 or 15(d) of the Exchange
Act, nor exempt from reporting pursuant to Rule 12g3-2(b) under the Exchange
Act, upon the written request of any Purchaser or Prior Purchaser, provide in
writing to such Purchaser or Prior Purchaser and to any prospective transferee
of any Shares or Registrable Shares of such Purchaser or Prior Purchaser the
information concerning the Company described in Rule 144A(d)(4) under the
Securities Act ("RULE 144A INFORMATION"). The Company also shall, upon the
written request of any Purchaser or Prior Purchaser, cooperate with and assist
such Purchaser or Prior Purchaser or any member of

                                       19
<PAGE>   20

the National Association of Securities Dealers, Inc. PORTAL system in applying
to designate and thereafter maintain the eligibility of the Shares or
Registrable Shares for trading through PORTAL. The Company's obligations under
this Section 8(b) (iv) shall at all times be contingent upon receipt from the
prospective transferee of Shares or Registrable Shares of a written agreement to
take all reasonable precautions to safeguard the Rule 144A Information from
disclosure to anyone other than persons who will assist such transferee in
evaluating the purchase of any Shares or Registrable Shares.

          (c)  REQUIRED REGISTRATIONS.

               (i)  At any time after the earlier of December 31, 2002, or the
closing of the Company's first underwritten public offering of shares of Common
Stock pursuant to a Registration Statement, a Stockholder or Stockholders
holding in the aggregate at least 35% of the Registrable Shares may request, in
writing, that the Company effect the registration on Form S-1 or Form S-2 (or
any successor form) of Registrable Shares owned by such Stockholder or
Stockholders having an aggregate offering price of at least $5,000,000 (based on
the then current market price or fair value). If the holders initiating the
registration intend to distribute the Registrable Shares by means of an
underwriting, they shall so advise the Company in their request. In the event
such registration is underwritten, the right of other Stockholders to
participate shall be conditioned on such Stockholders' participation in such
underwriting. Upon receipt of any such request, the Company shall promptly give
written notice of such proposed registration to all Stockholders. Such
Stockholders shall have the right, by giving written notice to the Company
within 30 days after the Company provides its notice, to elect to have included
in such registration such of their Registrable Shares as such Stockholders may
request in such notice of election, subject to the approval of the underwriter
managing the offering. Thereupon, the Company shall, as expeditiously as
possible, use its best efforts to effect the registration, on Form S-1 or Form
S-2 (or any successor form), of all Registrable Shares which the Company has
been requested to so register.

               (ii) At any time after the Company becomes eligible to file a
Registration Statement on Form S-3 (or any successor form relating to secondary
offerings), a Stockholder or Stockholders holding in the aggregate at least 25%
of the Registrable Shares may request the Company, in writing, to effect the
registration on Form S-3 (or such successor form), of Registrable Shares having
an aggregate offering price of at least $2,500,000 (based on the current public
market price). Upon receipt of any such request, the Company shall promptly give
written notice of such proposed registration to all Stockholders. Such
Stockholders shall have the right, by giving written notice to the Company
within 30 days after the Company provides its notice, to elect to have included
in such registration such of their Registrable Shares as such Stockholders may
request in such notice of election. Thereupon, the Company shall, as
expeditiously as possible, use its best efforts to effect the registration on
Form S-3, or such successor form, of all Registrable Shares which the Company
has been requested to register.

                                       20
<PAGE>   21

               (iii) The Company shall not be required to effect more than three
registrations pursuant to paragraph (i) above or more than four registrations
pursuant to paragraph (ii) above. In addition, the Company shall not be required
to effect any registration (other than on Form S-3 or any successor form
relating to secondary offerings) within six months after the effective date of
any other Registration Statement of the Company.

               (iv) If at the time of any request to register Registrable Shares
pursuant to this subsection 8(c), the Company is engaged or has fixed plans to
engage within 30 days of the time of the request in a registered public offering
as to which the Stockholders may include Registrable Shares pursuant to
subsection 8(d) or is engaged in any other activity which, in the good faith
determination of the Company's Board of Directors, would be adversely affected
by the requested registration to the material detriment of the Company, then the
Company may at its option direct that such request be delayed for a period not
in excess of six months from the effective date of such offering or the date of
commencement of such other material activity, as the case may be, such right to
delay a request to be exercised by the Company not more than once in any
two-year period.

     (d)  INCIDENTAL REGISTRATION.

          (i)  Whenever the Company proposes to file a Registration Statement
(other than pursuant to subsection 8(c) at any time and from time to time, it
will, prior to such filing, give written notice to all Stockholders of its
intention to do so and, upon the written request of a Stockholder or
Stockholders given within 20 days after the Company provides such notice (which
request shall state the intended method of disposition of such Registrable
Shares), the Company shall use its best efforts to cause all Registrable Shares
which the Company has been requested by such Stockholder or Stockholders to
register to be registered under the Securities Act to the extent necessary to
permit their sale or other disposition in accordance with the intended methods
of distribution specified in the request of such Stockholder or Stockholders;
provided that the Company shall have the right to postpone or withdraw any
registration effected pursuant to this subsection 8(d) without Obligation to any
Stockholder.

          (ii) In connection with any offering under this subsection 8(d)
involving an underwriting, the Company shall not be required to include any
Registrable Shares in such underwriting unless the holders thereof accept the
terms of the underwriting as agreed upon between the Company and the
underwriters selected by it, and then only in such quantity as will not, in the
opinion of the underwriters, jeopardize the success of the offering by the
Company. If in the opinion of the managing underwriter the registration of all,
or part of, the Registrable Shares which the holders have requested to be
included would materially and adversely affect such public offering, then the
Company shall be required to include in the underwriting only that number of
Registrable Shares, if any, which the managing underwriter believes may be sold
without causing such adverse effect. If the number of Registrable Shares to be
included in the underwriting in accordance with the foregoing is less than the
total number of

                                       21
<PAGE>   22

shares which the holders of Registrable Shares have requested to be included,
then the holders of Registrable Shares who have requested registration and other
holders of shares of Common Stock entitled to include shares of Common Stock in
such registration shall participate in the underwriting pro rata based upon
their total ownership of shares of Common Stock of the Company. If any holder
would thus be entitled to include more shares than such holder requested to be
registered, the excess shall be allocated among other requesting holders pro
rata based upon their total ownership of Registrable Shares.

          (e)  REGISTRATION PROCEDURES. If and whenever the Company is required
by the provisions of this Agreement to use its best efforts to effect the
registration of any of the Registrable Shares under the Securities Act, the
Company shall:

               (i)  file with the Commission a Registration Statement with
respect to such Registrable Shares and use its best efforts to cause that
Registration Statement to become and remain effective;

               (ii) as expeditiously as possible prepare and file with the
Commission any amendments and supplements to the Registration Statement and the
prospectus included in the Registration Statement as may be necessary to keep
the Registration Statement effective for a period of not less than 120 days from
the effective date;

               (iii) as expeditiously as possible furnish to each selling
Stockholder such reasonable numbers of copies of the prospectus, including a
preliminary prospectus in conformity with the requirements of the Securities
Act, and such other documents as the selling Stockholder may reasonably request
in order to facilitate the public sale or other disposition of the Registrable
Shares owned by the selling Stockholder; and

               (iv) as expeditiously as possible use its best efforts to
register or qualify the Registrable Shares covered by the Registration Statement
under the Securities or Blue Sky laws of such states as the selling Stockholders
shall reasonably request, and do any and all other acts and things that may be
necessary or desirable to enable the selling Stockholders to consummate the
public sale or other disposition in such states of the Registrable Shares owned
by the selling Stockholder; PROVIDED, HOWEVER, that the Company shall not be
required in connection with this paragraph (iv) to qualify as a foreign
corporation or execute a general consent to service of process in any
jurisdiction.

     If the Company has delivered preliminary or final prospectuses to the
selling Stockholders and after having done so the prospectus is amended to
comply with the requirements of the Securities Act, the Company shall promptly
notify the selling Stockholders and, if requested, the selling Stockholders
shall immediately cease making offers of Registrable Shares and return all
prospectuses to the Company. The Company shall promptly provide the selling
Stockholders with revised prospectuses and, following receipt of the revised
prospectuses,

                                       22
<PAGE>   23

the selling Stockholders shall be free to resume making offers of the
Registrable Shares.

          (f)  ALLOCATION OF EXPENSES. The Company will pay all Registration
Expenses of all registrations under this Agreement; provided, however, that if a
registration is withdrawn at the request of the Stockholders requesting such
registration (other than as a result of material adverse information concerning
the Business or financial condition of the Company which is made known to the
Stockholders after the date on which such registration was requested) and if the
requesting Stockholders elect not to have such registration counted as a
registration requested under subsection 8(c), the requesting Stockholders shall
pay the Registration Expenses of such registration pro rata in accordance with
the number of their Registrable Shares included in such registration. For
purposes of this Section, the term "Registration Expenses" shall mean all
expenses incurred by the Company in complying with this Section 8, including,
without limitation, all registration and filing fees, exchange listing fees,
printing expenses, fees and disbursements of counsel for the Company and the
fees and expenses of one counsel selected by the selling Stockholders to
represent the selling Stockholders, state Blue Sky fees and expenses, and the
expense of any special audits incident to or required by any such registration,
but excluding underwriting discounts, selling commissions and the fees and
expenses of selling Stockholders' own counsel (other than the counsel selected
to represent all selling Stockholders).

          (g)  INDEMNIFICATION. In the event of any registration of any of the
Registrable Shares under the Securities Act pursuant to this Agreement, the
Company will indemnify and hold harmless the seller of such Registrable Shares,
each underwriter of such Registrable Shares, and each other person, if any, who
controls such seller or underwriter within the meaning of the Securities Act or
the Exchange Act against any losses, claims, damages or liabilities, joint or
several, to which such seller, underwriter or controlling person may become
subject under the Securities Act, the Exchange Act, state securities or Blue Sky
laws or otherwise, insofar as such losses, claims, damages or liabilities (or
actions in respect thereof) arise out of or are based upon any untrue statement
or alleged untrue statement of any material fact contained in any Registration
Statement under which such Registrable Shares were registered under the
Securities Act, any preliminary prospectus or final prospectus contained in the
Registration Statement, or any amendment or supplement to such Registration
Statement, or arise out of or are based upon the omission or alleged omission to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading; and the Company will reimburse such seller,
underwriter and each such controlling person for any legal or any other expenses
reasonably incurred by such seller, underwriter or controlling person in
connection with investigating or defending any such loss, claim, damage,
liability or action; PROVIDED, HOWEVER, that the Company will not be liable in
any such case to the extent that any such loss, claim, damage or liability
arises out of or is based upon any untrue statement or omission made in such
Registration Statement, preliminary prospectus or prospectus, or any such
amendment or supplement, in reliance upon and in conformity with information
furnished to the Company, in writing, by or on behalf of such seller,
underwriter or controlling person specifically for use in the preparation
thereof.

                                       23
<PAGE>   24

     In the event of any registration of any of the Registrable Shares under the
Securities Act pursuant to this Agreement, each seller of Registrable Shares,
severally and not jointly, will indemnify and hold harmless the Company, each of
its directors and officers and each underwriter (if any) and each person, if
any, who controls the Company or any such underwriter within the meaning of the
Securities Act or the Exchange Act, against any losses, claims, damages or
liabilities, joint or several, to which the Company, such directors and
officers, underwriter or controlling person may become subject under the
Securities Act, Exchange Act, state securities or Blue Sky laws or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon any untrue statement or alleged untrue
statement of a material fact contained in any Registration Statement under which
such Registrable Shares were registered under the Securities Act, any
preliminary prospectus or final prospectus contained in the Registration
Statement, or any amendment or supplement to the Registration Statement, or
arise out of or are based upon any omission or alleged omission to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading, if the statement or omission was made in reliance upon
and in conformity with information furnished in writing to the Company by or on
behalf of such seller, specifically for use in connection with the preparation
of such Registration Statement, prospectus, amendment or supplement; PROVIDED,
HOWEVER, that the obligations of such Stockholders hereunder shall be limited to
an amount equal to the proceeds to each Stockholder of Registrable Shares sold
as contemplated herein.

     Each party entitled to indemnification under this subsection 8(g) (the
"INDEMNIFIED PARTY") shall give notice to the party required to provide
indemnification (the "INDEMNIFYING PARTY") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of any such claim or any
litigation resulting therefrom; PROVIDED, that counsel for the Indemnifying
Party, who shall conduct the defense of such claim or litigation, shall be
approved by the Indemnified Party (whose approval shall not be unreasonably
withheld); and, PROVIDED, FURTHER, that the failure of any Indemnified Party to
give notice as provided herein shall not relieve the Indemnifying Party of its
obligations under this Section 8. The Indemnified Party may participate in such
defense at such party's expense; PROVIDED, HOWEVER, that the Indemnifying Party
shall pay such expense if representation of such Indemnified Party by the
counsel retained by the Indemnifying Party would be inappropriate due to actual
or potential differing interests between the Indemnified Party and any other
party represented by such counsel in such proceeding. No Indemnifying Party, in
the defense of any such claim or litigation shall, except with the consent of
each Indemnified Party, consent to entry of any judgment or enter into any
settlement which does not include as an unconditional term thereof the giving by
the claimant or plaintiff to such Indemnified Party of a release from all
liability in respect of such claim or litigation, and no Indemnified Party shall
consent to entry of any judgment or settle such claim or

                                       24
<PAGE>   25

litigation without the prior written consent of the Indemnifying Party.

          (h)  INDEMNIFICATION WITH RESPECT TO UNDERWRITTEN OFFERING. In the
event that Registrable Shares are sold pursuant to a Registration Statement in
an underwritten offering pursuant to subsection 8(c)(i), the Company agrees to
enter into an underwriting agreement containing customary representations and
warranties with respect to the Business and operations of an issuer of the
Securities being registered and customary covenants and agreements to be
performed by such issuer, including without limitation customary provisions with
respect to indemnification by the Company of the underwriters of such offering.

          (i)  INFORMATION BY HOLDER. Each holder of Registrable Shares included
in any registration shall furnish to the Company such information regarding such
holder and the distribution proposed by such holder as the Company may request
in writing and as shall be required in connection with any registration,
qualification or compliance referred to in this Section 8.

          (j)  "STAND-OFF" AGREEMENT. Each Stockholder, if requested by the
Company and an underwriter of Common Stock or other Securities of the Company,
shall agree not to sell or otherwise transfer or dispose of any Registrable
Shares or other Securities of the Company held by such Stockholder for a
specified period of time (not to exceed 120 days) following the effective date
of a Registration Statement; PROVIDED, that:

               (i)  such agreement shall only apply to the first such
Registration Statement covering Common Stock of the Company to be sold on its
behalf to the public in an underwritten offering; and

               (ii) all Stockholders holding not less than the number of shares
of Common Stock held by such Stockholder (including shares of Common Stock
issuable upon the conversion of Shares, or other convertible Securities, or upon
the exercise of options, warrants or rights), all Founders and all officers and
directors of the Company enter into similar agreements.

Such agreement shall be in writing in a form satisfactory to the Company and
such underwriter. The Company may impose stop-transfer instructions with respect
to the Registrable Shares or other Securities subject to the foregoing
restriction until the end of the stand-off period.

          (k)  LIMITATIONS ON SUBSEQUENT REGISTRATION RIGHTS. The Company shall
not, without the prior written consent of Stockholders holding at least a
majority of the Registrable Shares, enter into any agreement (other than this
Agreement) with any holder or prospective holder of any Securities of the
Company which would allow such holder or prospective holder (i) to include
Securities of the Company in any registration filed under subsection 8(c) or
8(d), or (ii) to make a demand registration which could result in such
registration statement being declared effective prior to December 31, 2002.

                                       25
<PAGE>   26

          (l)  RULE 144 REQUIREMENTS. After the earliest of (i) the closing of
the sale of Securities of the Company pursuant to a Registration Statement, (ii)
the registration by the Company of a class of securities under Section 12 of the
Exchange Act, or (iii) the issuance by the Company of an offering circular
pursuant to Regulation A under the Securities Act, the Company agrees to:

               (i)  make and keep public information available, as those terms
are understood and defined in Rule 144 under the Securities Act;

               (ii) use its best efforts to file with the Commission in a timely
manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act (at any time after it has become subject to
such reporting requirements); and

               (iii) furnish to any holder of Registrable Shares upon request a
written statement by the Company as to its compliance with the reporting
requirements of said Rule 144 (at any time after 90 days following the closing
of the first sale of securities by the Company pursuant to a Registration
Statement), and of the Securities Act and the Exchange Act (at any time after it
has become subject to such reporting requirements), a copy of the most recent
annual or quarterly report of the Company, and such other reports and documents
of the Company as such holder may reasonably request to avail itself of any
similar rule or regulation of the Commission allowing it to sell any such
securities without registration.

          (m)  SELECTION OF UNDERWRITER. In the case of any registration
effected pursuant to subsection 8(c), the requesting Stockholders shall have the
right with the approval of the Board of Directors of the Company, which approval
shall not be unreasonably withheld, to designate the managing underwriter in any
underwritten offering.

     9.   SUCCESSORS AND ASSIGNS. Except as provided in Section 10, the
provisions of this Agreement shall be binding upon, and inure to the benefit of,
the respective successors, assigns, heirs, executors and administrators of the
parties hereto.

     10.  TRANSFERS OF CERTAIN RIGHTS.

          (a)  TRANSFER. The rights granted to a Purchaser or Prior Purchaser
under subsections 7(b) and 7(f) and Section 8 may be transferred by such
Purchaser or Prior Purchaser to any transferee pursuant to Section 8(b)(ii) or
to any person or entity acquiring at least Two Hundred Fifty Thousand (250,000)
Shares or Registrable Shares; PROVIDED, HOWEVER, that the Company is given
written notice by the transferee at the time of such transfer stating the name
and address of the transferee and identifying the securities with respect to
which such rights are being assigned.

                                       26
<PAGE>   27

          (b)  TRANSFEREES. Any transferee (other than a Purchaser or Prior
Purchaser) to whom rights under subsection 7(b), subsection 7(f) or Section 8
are transferred shall, as a condition to such transfer, deliver to the Company a
written instrument by which such transferee agrees to be bound by the
obligations imposed upon Purchasers and Prior Purchasers under subsection 7(f)
and Section 8, as the case may be, to the same extent as if such transferee were
a Purchaser or Prior Purchaser hereunder.

          (c)  SUBSEQUENT TRANSFEREES. A transferee to whom rights are
transferred pursuant to this Section 10 may not again transfer such rights to
any other person or entity, other than as provided in (a) or (b) above.

          (d)  EQUITYHOLDERS. Notwithstanding anything to the contrary herein,
any Purchaser or Prior Purchaser may transfer rights granted to such Purchaser
or Prior Purchaser under subsection 7(b), subsection 7(f) or Section 8 to any
direct or indirect equityholder thereof which is a partnership, corporation or
limited liability company and in turn to the respective partners, stockholders
or members of such entities, provided such transferee delivers to the Company a
written instrument in accordance with subparagraph (b) above which contains a
representation that the transfer is exempt from registration under the
Securities Act and designates a person or entity affiliated with the purchaser
or Prior Purchaser (the "DESIGNATED NOTICE PARTY") to receive notice hereunder
on behalf of the transferee. In the event of such transfer, such partner or
stockholder shall be deemed a Purchaser or Prior Purchaser for purposes of this
Section 10 and may again transfer such rights to any other person or entity
which acquires Shares or Registrable Shares from such partner or stockholder, in
accordance with, and subject to, the provisions of subparagraphs (a), (b) and
(c) above.

     11.  SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All agreements,
representations and warranties contained herein shall survive the execution and
delivery of this Agreement and the closing of the transactions contemplated
hereby.

     12.  NOTICES. All notices, requests, consents, and other communications
under this Agreement shall be in writing and shall be delivered by hand or
mailed by first class certified or registered mail, return receipt requested,
postage prepaid:

     If to the Company, at 211 Second Avenue, Waltham, Massachusetts 02154,
Attention: President, or at such other address or addresses as may have been
furnished in writing by the Company to the Purchasers.

     If to a Purchaser, Prior Purchaser or Founder, at his or its address set
forth on EXHIBIT D attached hereto, to the Designated Notice Party for a
Purchaser or Prior Purchaser, if any, or at such other address or addresses as
may have been furnished to the Company in writing by such Purchaser, Prior
Purchaser or Founder.

                                       27
<PAGE>   28

     Notices provided in accordance with this Section 12 shall be deemed
delivered upon personal delivery or 72 hours after deposit in the U.S. Mail.

     13.  BROKERS. The Company and each Purchaser, or with respect to Calvert
Social Investment Fund, its investment advisor Calvert Asset Management Company,
Inc. (i) represents and warrants to the other parties hereto that he or it has
retained no finder or broker in connection with the transactions contemplated by
this Agreement, other than the Company's retention of GreenPartners BV, and (ii)
will indemnify and save the other parties harmless from and against any and all
claims, liabilities or obligations with respect to brokerage or finders' fees or
commissions, or consulting fees in connection with the transactions contemplated
by this Agreement asserted by any person on the basis of any statement or
representation alleged to have been made by such indemnifying party.

     14.  EXPENSES. The Company shall pay the fees and expenses of counsel for
the Purchasers in connection with the transactions contemplated hereby, such
amount not to exceed an aggregate of $15,000 payable to Hale and Dorr LLP.

     15.  ENTIRE AGREEMENT. This Agreement embodies the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior agreements and understandings relating to such
subject matter.

     16.  AMENDMENTS AND WAIVERS.

          (a)  Except as otherwise expressly set forth in this Agreement, any
term of this Agreement may be amended and the observance of any term of this
Agreement may be waived (either generally or in a particular instance and either
retroactively or prospectively), with the written consent of the Company and the
holders of at least 60% of the Registrable Shares; provided, that (i) no
Purchaser's or Prior Purchaser's rights under any representation or warranty
pursuant to Section 3 of this Agreement, under Section 5, or under Section 7(a)
or 7(b) of this Agreement shall be waived without such party's written consent,
and (ii) no amendment to this Agreement which by its terms specifies that any
particular Purchaser's or Prior Purchaser's rights shall be waived or abridged
in a manner which is inconsistent with the waiver or abridgement of the rights
of the other Purchasers or Prior Purchasers pursuant to such amendment shall be
approved without the written consent of such specified party. The provisions of
Sections 7(b), 7(f), 7(g), 8 and 10 of this Agreement shall amend and restate in
their entirety Sections 7(b), 7(f), 7(g), 8 and 10 of the Series C Preferred
Stock Purchase Agreement dated April 30, 1998, as amended, by and among the
Company, the Founders and the Purchasers named therein (the "SERIES C
AGREEMENT"); and such Sections 7(b), 7(f), 7(g), 8 and 10 of the Series C
Agreement are hereby terminated and shall be of no further force or effect.

          (b)  By their execution and delivery of this Agreement, the Founders
and the

                                       28
<PAGE>   29

Prior Purchasers hereby waive any and all rights of first refusal or preemptive
rights of any kind with respect to the issuance and sale of the Series D
Preferred and the issuance of Common Stock upon conversion of the Series D
Preferred in accordance with the terms thereof, including without limitation the
right of first refusal contained in Section 7(f) of the Series C Agreement.

          (c)  By their execution and delivery of this Agreement, pursuant to
Section 7(g) of the Series C Agreement, the undersigned Purchasers and Prior
Purchasers hereby affirmatively consent to (i) the issuance and sale of the
Shares as described herein, and (ii) the issuance and delivery of Common Stock
upon the conversion of such Series D Preferred in accordance with the terms of
such Series D Preferred.

     17.  COUNTERPARTS. This Agreement may be executed in several counterparts,
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument.

     18.  HEADINGS. The headings of the sections, subsections, and paragraphs of
this Agreement have been added for convenience only and shall not be deemed to
be a part of this Agreement.

     19.  SEVERABILITY. The invalidity or unenforceability of any provision of
this Agreement shall not affect the validity or enforceability of any other
provision.

     20.  GOVERNING LAW. This Agreement shall be governed by and construed in
accordance with the laws of the State of Delaware.

                                       29
<PAGE>   30

     IN WITNESS WHEREOF, the undersigned have hereunto set their hands as of the
day and year first above written.

                                            COMPANY:

                                            EVERGREEN SOLAR, INC.

                                            By:  /s/ Mark A. Farber
                                                 -------------------------------
                                                 Name:
                                                 Title:

                                            FOUNDERS:

                                            /s/ Richard G. Chleboski
                                            ------------------------------------
                                            Richard G. Chleboski

                                            /s/ Mark A. Farber
                                            ------------------------------------
                                            Mark A. Farber

                                            /s/ Jack I. Hanoka
                                            ------------------------------------
                                            Jack I. Hanoka

                                            [Purchasers' and Prior Purchasers'
                                            signatures are attached]

                                       30
<PAGE>   31

               SIGNATURE PAGE TO SERIES D PREFERRED STOCK PURCHASE
                       AGREEMENT OF EVERGREEN SOLAR, INC.

                                      Kawasaki Heavy Industries, Ltd.
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Masayuki Yokoyama
                                      ------------------------------------------
                                      Signature: Masayuki Yokoyama
                                                 Executive Managing Director

                                      UVCC Fund II
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser
                                      By: Arete Venture Investors II, L.P.

                                      /s/ Robert W. Shaw, Jr.
                                      ------------------------------------------
                                      Signature: Robert W. Shaw, Jr.
                                                 General Partner

                                      UVCC II Parallel Fund, L.P.
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser
                                      By: Arete Ventures L.P. III

                                      /s/ Robert W. Shaw, Jr.
                                      ------------------------------------------
                                      Signature: Robert W. Shaw, Jr.
                                                 General Partner

                                       31
<PAGE>   32

                                      UTECH Climate Challenge Fund, L.P.
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser
                                      By: Arete Climate Challenge Partners, LLC

                                      /s/ Robert W. Shaw, Jr.
                                      ------------------------------------------
                                      Signature:   Robert W. Shaw, Jr.
                                                   Managing Member

                                      Micro-generation Technology Fund, L.L.C.
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser
                                      By: Arete Corporation Manager

                                      /s/ Robert W. Shaw, Jr.
                                      ------------------------------------------
                                      Signature: Robert W. Shaw, Jr.
                                                 President

                                      1995 Willrich Trust
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Mason Willrich, Trustee
                                      ------------------------------------------
                                      Signature: Mason Willrich
                                                 Trustee

                                      Miller Associates Trust #1
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Robert F. Miller
                                      ------------------------------------------
                                      Signature: Robert F. Miller
                                                 Trustee

                                       32
<PAGE>   33

                               Solstice Capital Limited Partnership
                               -------------------------------------------------
                               Name of Purchaser or Prior Purchaser
                               By: Solstice Capital GP Limited
                                    Partnership, General Partner

                               /s/ Henry Newman
                               -------------------------------------------------
                               Signature: Henry Newman
                                          General Partner

                               Odyssey Fund
                               -------------------------------------------------
                               Name of Purchaser or Prior Purchaser

                               /s/ Ann Partlow
                               -------------------------------------------------
                               Signature: Ann Partlow
                                          Authorized  Signatory

                               Calvert Social Investment Fund Balanced Portfolio
                               -------------------------------------------------
                               Name of Purchaser or Prior Purchaser

                               /s/ Susan Walker Bender
                               -------------------------------------------------
                               Signature: Susan Walker Bender
                                          Asst. Secretary and Authorized Signer

                               Nth Power Technologies Fund I., L.P.
                               -------------------------------------------------
                               Name of Purchaser or Prior Purchaser

                               /s/ Tim Woodward
                               -------------------------------------------------
                               Signature: Tim Woodward
                                          Officer of the General Partner

                                       33
<PAGE>   34

                                      Swiss Reinsurance Company
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Bruno Letsch
                                      ------------------------------------------
                                      Signature: Bruno Letsch
                                                 Head of Investment Center
                                                  Europe

                                      /s/ Harold Weiss
                                      ------------------------------------------
                                      Signature: Harold Weiss
                                                 Member of the Management

                                      Joshua C. Lampl
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Joshua C. Lampl
                                      ------------------------------------------
                                      Signature: Joshua C. Lampl

                                      Zero Stage Capital VI, L.P.
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Gordon Baty
                                      ------------------------------------------
                                      Signature: Gordon Baty
                                                 General Partner

                                      ZERO STAGE CAPITAL V, L.P.
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Gordon Baty
                                      ------------------------------------------
                                      Signature: Gordon Baty
                                                 General Partner

                                       34
<PAGE>   35

                                      Volcom Holding Ltd.
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Herbert Kuhn
                                      ------------------------------------------
                                      Signature: Illegible
                                      By Power of Attorney for Herbert Kuhn

                                      Nikel T. Lambrechtsen
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Nikel T. Lambrechtsen
                                      ------------------------------------------
                                      Signature:   Nikel T. Lambrechtsen

                                      Eisso Rost Crollius
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Eisso Rost Crollius
                                      ------------------------------------------
                                      Signature:

                                      VIMAC ES LP
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ William C. Osborn
                                      ------------------------------------------
                                      Signature: William C. Osborn
                                                 Manager, VIMAC LLC, General
                                                  Partner

                                       35
<PAGE>   36

                                      VIMAC ES2 LP
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ William C. Osborn
                                      ------------------------------------------
                                      Signature: William C. Osborn
                                                 Manager, VIMAC LLC, General
                                                  Partner

                                      Albin Income Trust
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Laura L. Futrell
                                      ------------------------------------------
                                      Signature: Laura L. Futrell
                                                 Trustee

                                      Saint Mary's College of California
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ Kristine L. Chase
                                      ------------------------------------------
                                      Signature: Kristine L. Chase
                                                 Vice President for
                                                  Administration
                                                 Chief Financial Officer

                                      P. H. DeKoster
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ P. H. DeKoster
                                      ------------------------------------------
                                      Signature:   P. H. DeKoster

                                       36
<PAGE>   37

                                      Liberty Environmental
                                      ------------------------------------------
                                      Name of Purchaser or Prior Purchaser

                                      /s/ D.C. Holway
                                      ------------------------------------------
                                      Signature: D.C. Holway
                                                 General Partner

                                       37
<PAGE>   38

                                    EXHIBIT A

                        (amended as of January 26, 2000)

                                   PURCHASERS

<TABLE>
<CAPTION>
Name and Address of Purchaser                                          Number of Shares
-----------------------------                                          ----------------

Initial Closing Purchasers:
---------------------------

<S>                                                                     <C>
Kawasaki Heavy Industries, Ltd.                                            2,000,000
Tokyo Head Office, World
  Trade Center Building
4-1 Hamamatsu-cho 2-chome
Minato-ku
Tokyo 105-6116
Japan

UVCC Fund II                                                                 240,000
3 Bethesda Metro Center, Suite 770
Bethesda, MD 20814

UVCC II Parallel Fund, L.P.                                                  240,000
3 Bethesda Metro Center, Suite 770
Bethesda, MD 20814

Utech Climate Challenge Fund, L.P.                                           240,000
3 Bethesda Metro Center, Suite 770
Bethesda, MD 20814

Micro-Generation Technology Fund, LLC                                        300,000
c/o Arete Corporation
P.O. Box 1299
Center Harbor, NH 03226

1995 Willrich Trust
c/o Mason Willrich, Trustee                                                   40,059
38 Dudley Court
Piedmont, CA 94611
</TABLE>

                                       38
<PAGE>   39

<TABLE>
<CAPTION>
<S>                                                                        <C>
Miller Associates Trust #1                                                   160,000
11 Drew Road
Newton, MA 02167

Solstice Capital Limited Partnership                                         100,000
33 Broad Street
Boston, MA 02109

Odyssey Fund                                                                 200,000
c/o Rockefeller & Co., Inc.
30 Rockefeller Plaza
New York, NY 10012

Calvert Social Investment Fund                                                80,162
Balanced Portfolio
4550 Montgomery Avenue, 1000N
Bethesda, MD 20814

Nth Power Technologies Fund I, L.P.                                          801,623
100 Spear Street
Suite 1450
San Francisco, CA 94105

Swiss Reinsurance Company                                                    801,479
Mythenquai 50/60
CH 8022 Zurich
Switzerland

Josh Lampl                                                                    40,000
1106 Second Street
Suite 212
Encinitas, CA92024

Second Closing Purchasers:
-------------------------

Zero Stage Capital VI, L.P.                                                1,000,000
c/o Zero Stage Capital
101 Main Street
Cambridge, MA 02142
</TABLE>

                                       39
<PAGE>   40

<TABLE>
<CAPTION>
<S>                                                                          <C>
Zero Stage Capital V, L.P.                                                   200,000
101 Main Street
Cambridge, MA 02142

THIRD CLOSING PURCHASERS:

Volcom Holding Ltd.
c/o Nicholas Parker                                                          800,000
Managing Director - Private Equity
SAM Sustainability Group AG
170 Bloor Street West, Suite 804
Toronto, Ontario, Canada M5S 1T9
Tel: 1-416-944-1299
Fax: 1-416-944-8915

Eisso Roest Crollius                                                          40,000
Lange Voorhout 29
2514 EB Den Haag
The Netherlands
Tel: 070-362-4818
Fax: 070-362-2598

Nikel Lambrechtsen                                                            60,000
Benedendorpsweg 138
6862 WP Oosterbeek
The Netherlands
Tel: 026-339-2439
Fax: 026-339-2851
</TABLE>

                                       40
<PAGE>   41

                                PRIOR PURCHASERS

UVCC Fund II
UVCC II Parallel Fund, L.P.
Utech Climate Challenge Fund, L.P.
Micro-Generation Technology Fund, LLC
Zero Stage Capital V L.P.
Liberty Environmental Partners, L.P.
VIMAC ES Limited Partnership
Albin Income Trust
Josh Lampl
St. Mary's College of California
Markus G. Real
Sarasin International Securities Ltd.
P.H. de Koster
Nichimen Corporation
Solstice Capital Limited Partnership
Odyssey Fund
Calvert Social Investment Fund Balanced Portfolio
Swiss Reinsurance Company
Nth Power Technologies Fund I, L.P.
VIMAC ES 2 Limited Partnership

                                       41
<PAGE>   42

                                    EXHIBIT B
                                    ---------

                           FORM OF AMENDED CERTIFICATE

                                     OMITTED

<PAGE>   43

                                    EXHIBIT C
                                    ---------

                  EXCEPTIONS TO REPRESENTATIONS AND WARRANTIES

                                     OMITTED

<PAGE>   44

                                    EXHIBIT D
                                    ---------

                              LIST OF STOCKHOLDERS

                                     OMITTED

<PAGE>   45

                                    EXHIBIT E
                                    ---------

                        FORM OF NONDISCLOSURE AGREEMENTS

                                     OMITTED

<PAGE>   46

                                    EXHIBIT F
                                    ---------

                            CERTIFICATE OF INSURANCE

                                     OMITTED

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