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                                                                    EXHIBIT 10.8

                               SECURITY AGREEMENT

     SECURITY AGREEMENT (as amended, restated, supplemented or otherwise
modified from time to time in accordance herewith and including all attachments,
exhibits and schedules hereto, the "AGREEMENT"), dated as of February 18, 2003,
made by SATCON TECHNOLOGY CORPORATION, a Delaware corporation (the "GRANTOR"),
in favor of each of the Secured Parties whose names are set forth on Exhibit A
hereto (collectively, the "SECURED PARTIES").

     WHEREAS, the Grantor has issued separate secured convertible promissory
notes to the Secured Parties (the "NOTES") in the aggregate principal amount of
$832,500 pursuant to a Note and Warrant Purchase Agreement by and among the
Grantor and the Secured Parties dated the date hereof (the "PURCHASE
AGREEMENT"); and

     WHEREAS, it is a condition precedent to the Secured Parties making the loan
evidenced by the Purchase Agreement to the Grantor that the Grantor execute and
deliver to the Secured Parties a security agreement providing for the grant to
the Secured Parties of a continuing security interest in all personal property
and assets of the Grantor, all in substantially the form hereof to secure all
Obligations (hereinafter defined); and

     WHEREAS, all rights, remedies and obligations of the parties to this
Agreement are subject to (i) the provisions of that certain Subordination
Agreement by and between the Secured Party and Silicon Valley Bank dated as of
February 18, 2003, and (ii) the rights of Silicon Valley Bank under the SVB Loan
Agreement.

     NOW, THEREFORE, the parties agree as follows:

                             ARTICLE I. DEFINITIONS

     Section 1.1. DEFINITION OF TERMS USED HEREIN. All capitalized terms used
herein and not defined herein have the respective meanings provided therefor in
the Purchase Agreement. All terms defined in the Uniform Commercial Code
(hereinafter defined) as in effect from time to time and used herein and not
otherwise defined herein (whether or not such terms are capitalized) have the
same definitions herein as specified therein.

     Section 1.2. DEFINITION OF CERTAIN TERMS USED HEREIN. As used herein, the
following terms have the following meanings:

     "COLLATERAL" means all accounts receivable of the Grantor and all personal
and fixture property of every kind and nature, including, without limitation,
all furniture, fixtures, equipment, raw materials, inventory, or other goods,
accounts, contract rights, rights to the payment of money, insurance refund
claims and all other insurance claims and proceeds, tort claims, chattel paper,
documents, instruments, securities and other investment property, deposit
accounts, rights to proceeds of letters of credit and all general intangibles
including, without limitation, all tax refund claims, license fees, patents,
patent licenses, patent applications, trademarks, trademark licenses, trademark
applications, trade names, copyrights, copyright licenses, copyright
applications, rights to sue and recover for past infringement of patents,
trademarks and copyrights, computer programs, computer software, engineering
drawings,

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service marks, customer lists, goodwill, and all licenses, permits, agreements
of any kind or nature pursuant to which the Grantor possesses, uses or has
authority to possess or use property (whether tangible or intangible) of others
or others possess, use or have authority to possess or use property (whether
tangible or intangible) of the Grantor, and all recorded data of any kind or
nature, regardless of the medium of recording including, without limitation, all
books and records, software, writings, plans, specifications and schematics; and
all proceeds and products of each of the foregoing.

     "DEFAULT" means any event or circumstance which, with the giving of notice,
the lapse of time, or both, would (if not cured, waived, or otherwise remedied
during such time) constitute an Event of Default.

     "EVENT OF DEFAULT" has the meaning specified in the Notes.

     "INDEMNITEES" has the meaning specified in Section 7.5(b).

     "LIEN" means: (i) any interest in property securing an obligation owed to,
or a claim by, a Person other than the owner of the property, whether such
interest is based on the common law, statute, or contract, and including a
security interest, charge, claim, or lien arising from a mortgage, deed of
trust, encumbrance, pledge, hypothecation, assignment, deposit arrangement,
agreement, security agreement, conditional sale or trust receipt or a lease,
consignment or bailment for security purposes; (ii) to the extent not included
under CLAUSE (i), any reservation, exception, encroachment, easement,
right-of-way, covenant, condition, restriction, lease or other title exception
or encumbrance affecting property; and (iii) any contingent or other agreement
to provide any of the foregoing.

     "NOTES" has the meaning assigned to such term in the first recital of this
Agreement.

     "PERMITTED LIEN" has the meaning set forth in the SVB Loan Agreement.

     "OBLIGATIONS" means all indebtedness, liabilities, obligations, covenants
and duties of the Grantor to the Secured Parties of every kind, nature and
description, direct or indirect, absolute or contingent, due or not due,
contractual or tortious, liquidated or unliquidated, arising by operation of law
or otherwise, now existing of hereafter arising under or in connection with the
Notes, the Purchase Agreement, this Agreement or the other Transaction
Documents.

     "REGISTERED ORGANIZATION" means an entity formed by filing a registration
document with a United States Governmental Authority, such as a corporation,
limited partnership or limited liability company.

     "SECURITY INTEREST" has the meaning specified in Section 2.1 of this
Agreement.

     "SVB LOAN AGREEMENT" means that certain Loan and Security Agreement by and
between the Grantor and Silicon Valley Bank, dated September 13, 2002, as
amended.

     "UNIFORM COMMERCIAL CODE" means the Uniform Commercial Code from time to
time in effect in the State of New York.

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                          ARTICLE II. SECURITY INTEREST

     Section 2.1. SECURITY INTEREST. As security for the payment and
performance, in full of the Obligations, and any extensions, renewals,
modifications or refinancings of the Obligations, the Grantor hereby bargains,
sells, conveys, assigns, sets over, mortgages, pledges, hypothecates and
transfers to the Secured Parties, and hereby grants to the Secured Parties,
their successors and assigns, a security interest in, all of such Grantor's
right, title and interest in, to and under the Collateral (the "SECURITY
INTEREST").

     Section 2.2. NO ASSUMPTION OF LIABILITY. The Security Interest is granted
as security only and shall not subject the Secured Parties to, or in any way
alter or modify, any obligation or liability of the Grantor with respect to or
arising out of the Collateral.

                  ARTICLE III. REPRESENTATIONS AND WARRANTIES

     The Grantor represents and warrants to the Secured Parties that:

     Section 3.1. TITLE AND AUTHORITY. The Grantor has good and valid rights in
and title to the Collateral with respect to which it has purported to grant a
security interest hereunder and has full power and authority to grant to the
Secured Parties the Security Interest and to execute, deliver and perform its
obligations in accordance with the terms of this Agreement, without the consent
or approval of any other Person other than any consent or approval which has
been obtained.

     Section 3.2. FILINGS; ACTIONS TO ACHIEVE PERFECTION. Fully executed Uniform
Commercial Code financing statements (including fixture filings, as applicable)
or other appropriate filings, recordings or registrations containing a
description of the Collateral have been delivered to the Secured Parties for
filing in each United States governmental, municipal or other office specified
in Schedule A, which are all the filings, recordings and registrations that are
necessary to publish notice of and protect the validity of and to establish a
legal, valid and perfected security interest in favor of the Secured Parties in
respect of all Collateral in which the Security Interest may be perfected by
filing, recording or registration in the United States (or any political
subdivision thereof) and its territories and possessions, and no further or
subsequent filing, refiling, recording, rerecording, registration or
reregistration is necessary in any such jurisdiction, except as provided under
applicable law with respect to the filing of continuation statements or with
respect to the filing of amendments or new filings to reflect the change of the
Grantor's name, location, identity or corporate structure. The Grantor's name is
listed in the preamble of this Agreement identically to how it appears on its
certificate of incorporation or other organizational documents.

     Section 3.3. VALIDITY AND PRIORITY OF SECURITY INTEREST. The Security
Interest constitutes (a) a legal and valid security interest in all the
Collateral securing the payment and performance of the Obligations, (b) subject
only to the filings described in Section 3.2 above and other previously
perfected security interests in the Collateral listed on Schedule 3.3 to this
Agreement ("EXISTING LIENS") and Permitted Liens, a perfected security interest
in all Collateral in which a security interest may be perfected by filing,
recording or registration in the United States pursuant to the Uniform
Commercial Code or other applicable law in the United States (or any political
subdivision thereof) and its territories and possessions or any other country,
state or

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nation (or any political subdivision thereof). The Security Interest is
and shall be subordinate to any other Existing Lien on any of the Collateral.

     Section 3.4. ABSENCE OF OTHER LIENS. The Grantor's Collateral is owned by
the Grantor free and clear of any Lien other than Existing Liens and Permitted
Liens. Without limiting the foregoing and except as set forth on Schedule 3.4 to
this Agreement, the Grantor has not filed or consented to any filing described
in Section 3.2 in favor of any Person other than the Secured Parties, nor
permitted the granting or assignment of a security interest or permitted
perfection of any security interest in the Collateral in favor of any Person
other than the Secured Parties. The Secured Parties' having possession of all
instruments and cash constituting Collateral from time to time and the filing of
financing statements in the offices referred to in Schedule A hereto results in
the perfection of such security interest. Such security interest is, or in the
case of Collateral in which the Grantor obtain rights after the date hereof,
will be, a perfected security interest. Such notices, filings and all other
action necessary or desirable to perfect and protect such security interest have
been duly taken.

     Section 3.5. VALID AND BINDING OBLIGATION. This Agreement constitutes the
legal, valid and binding obligation of the Grantor, enforceable against the
Grantor in accordance with its terms, except (i) as limited by applicable
bankruptcy, insolvency, reorganization, moratorium, and other laws of general
application affecting enforcement of creditors' rights generally, (ii) as
limited by laws relating to the availability of specific performance, injunctive
relief, or other equitable remedies, (iii) as limited by the Subordination
Agreement by and between the Secured Party and Silicon Valley Bank, and (iv) to
the extent the indemnification provisions contained in this Agreement may be
limited by applicable federal or state securities laws.

                             ARTICLE IV. COVENANTS

     Section 4.1. CHANGE OF NAME; LOCATION OF COLLATERAL; PLACE OF BUSINESS,
STATE OF FORMATION OR ORGANIZATION.

            (a)  The Grantor shall notify the Secured Parties in writing
     promptly of any change (i) in its corporate name or in any trade name used
     to identify it in the conduct of its business or in the ownership of its
     properties, (ii) in the location of its chief executive office, its
     principal place of business, any office in which it maintains books or
     records relating to Collateral owned by it (including the establishment of
     any such new office or facility), (iii) in its identity or corporate
     structure such that a filed filing made under the Uniform Commercial Code
     becomes misleading or (iv) in its Federal Taxpayer Identification Number.
     In extension of the foregoing, the Grantor shall not effect or permit any
     change referred to in the preceding sentence unless all filings have been
     made under the Uniform Commercial Code or otherwise that are required in
     order for the Secured Parties to continue at all times following such
     change to have a valid, legal and perfected security interest in all the
     Collateral.

            (b)  Without limiting Section 4.1(a), without the prior written
     consent of the Secured Parties in each instance, the Grantor shall not
     change its (i) principal residence, if it is an individual, (ii) place of
     business, if it has only one place of business and is not a Registered
     Organization, (iii) principal place of business, if it has more than one
     place of

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     business and is not a Registered Organization, or (iv) state of
     incorporation, formation or organization, if it is a Registered
     Organization.

     Section 4.2. RECORDS. The Grantor shall maintain, at its own cost and
expense, such complete and accurate records with respect to the Collateral owned
by it as is consistent with its current practices and in accordance with such
prudent and standard practices used in industries that are the same as or
similar to those in which the Grantor is engaged, but in any event to include
complete accounting records indicating all payments and proceeds received with
respect to any part of the Collateral, and, at such time or times as the Secured
Parties may reasonably request, promptly to prepare and deliver to the Secured
Parties a duly certified schedule or schedules in form and detail satisfactory
to the Secured Parties showing the identity, amount and location of any and all
Collateral.

     Section 4.3. PERIODIC CERTIFICATION; NOTICE OF CHANGES. In the event there
should at any time be any change in the information represented and warranted
herein or in the documents and instruments executed and delivered in connection
herewith, the Grantor shall immediately notify the Secured Parties in writing of
such change (this notice requirement shall be in extension of and shall not
limit or relieve the Grantor of any other covenants hereunder).

     Section 4.4. PROTECTION OF SECURITY. The Grantor shall, at its own cost and
expense, take any and all actions necessary to defend title to the Collateral
against all persons and to defend the Security Interest of the Secured Parties
in the Collateral and the priority thereof against any Lien other than Existing
Liens and Permitted Liens.

     Section 4.5. INSPECTION AND VERIFICATION. The Secured Parties and such
persons as the Secured Parties may reasonably designate shall have the right to
inspect the Collateral, all records related thereto (and to make extracts and
copies from such records) and the premises upon which any of the Collateral is
located, to discuss the Grantor's affairs with the officers of the Grantor and
its independent accountants and to verify under reasonable procedures the
validity, amount, quality, quantity, value, condition and status of, or any
other matter relating to, the Collateral, including, in the case of collateral
in the possession of any third Person and upon an Event of Default, by
contacting any account debtor or third Person possessing such Collateral for the
purpose of making such a verification. Out-of-pocket expenses in connection with
any inspections by representatives of the Secured Parties shall be (a) the
obligations of the Grantor with respect to any inspection after the Secured
Parties' demand payment of the Notes or (b) the obligation of the Secured
Parties in any other case.

     Section 4.6. TAXES; ENCUMBRANCES. At their option, the Secured Parties may
discharge Liens, other than Existing Liens and Permitted Liens, at any time
levied or placed on the Collateral and may pay for the maintenance and
preservation of the Collateral to the extent the Grantor fails to do so and the
Grantor shall reimburse the Secured Parties on demand for any payment made or
any expense incurred by the Secured Parties pursuant to the foregoing
authorization; provided, however, that nothing in this Section shall be
interpreted as excusing the Grantor from the performance of, or imposing any
obligation on the Secured Parties to cure or perform, any covenants or other
obligation of the Grantor with respect to any Lien or maintenance or
preservation of Collateral as set forth herein.

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     Section 4.7. USE AND DISPOSITION OF COLLATERAL. The Grantor shall not make
or permit to be made an assignment, pledge or hypothecation of any Collateral or
shall grant any other Lien in respect of the Collateral other than Existing
Liens and Permitted Liens without the prior written consent of the Secured
Parties. The Grantor shall not make or permit to be made any transfer of any
Collateral and the Grantor shall remain at all times in possession of the
Collateral owned by it, other than with respect to Existing Liens and other
liens approved by the Secured Parties.

     Section 4.8. INSURANCE/NOTICE OF LOSS. Within a reasonable period of time
following the date of this Agreement, Grantor, at its own expense, shall
maintain or cause to be maintained insurance covering physical loss or damage to
the Collateral. In extension of the foregoing and without limitation, such
insurance shall be payable to the Secured Parties as loss payee under a
"standard" loss payee clause, and the Secured Parties shall be listed as an
"additional insured" on Grantor's general liability insurance. Such insurance
shall not be terminated, cancelled or not renewed for any reason, including
non-payment of insurance premiums, unless the insurer shall have provided the
Secured Parties at least 30 days prior written notice. Grantor irrevocably
makes, constitutes and appoints the Secured Parties (and all officers, employees
or agents designated by the Secured Parties) as its true and lawful agent and
attorney-in-fact for the purpose, at any time following the Secured Parties'
demand for payment of the Notes, of making, settling and adjusting claims in
respect of Collateral under policies of insurance, endorsing the name of Grantor
on any check, draft, instrument or other item of payment for the proceeds of
such policies of insurance and for making all determinations and decisions with
respect thereto. In the event that Grantor at any time or times shall fail to
obtain or maintain any of the policies of insurance required hereby or to pay
any premium in whole or part relating thereto, the Secured Parties may, without
waiving or releasing any obligation or liability of Grantor hereunder, in their
sole discretion, obtain and maintain such policies of insurance and pay such
premium and take any other actions with respect thereto as the Secured Parties
deem advisable. All sums disbursed by the Secured Parties in connection and in
accordance with this Section, including reasonable attorneys' fees, court costs,
expenses and other charges relating thereto, shall be payable upon demand, by
Grantor to the Secured Parties and shall be additional Obligations secured
hereby. Grantor shall promptly notify the Secured Parties if any material
portion of the Collateral owned or held by Grantor is damaged or destroyed. The
proceeds of any casualty insurance in respect of any casualty loss of any of the
Collateral shall (i) so long as the Secured Parties have not demanded payment of
the Notes, be disbursed to Grantor for direct application by Grantor solely to
the repair or replacement of Grantor's property so damaged or destroyed, and
(ii) in all other circumstances, be held by the Secured Parties as cash
collateral for the Obligations. The Secured Parties may, at their sole option,
disburse from time to time all or any part of such proceeds so held as cash
collateral, upon such terms and conditions as the Secured Parties may reasonably
prescribe, for direct application by the Secured Parties solely to the repair or
replacement of Grantor's property so damaged or destroyed, or Grantor may apply
all or any part of such proceeds to the Obligations.

     Section 4.9. LEGEND. Grantor shall legend, in form and manner satisfactory
to the Secured Parties, its accounts and its books, records and documents
evidencing or pertaining thereto with an appropriate reference to the fact that
such accounts have been assigned to the Secured Parties and that the Secured
Parties have a security interest therein.

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                ARTICLE V. FURTHER ASSURANCES; POWER OF ATTORNEY

     Section 5.1. FURTHER ASSURANCES. Grantor shall, at its own expense,
execute, acknowledge, deliver and cause to be duly filed all such further
instruments and documents and take all such actions as the Secured Parties may
from time to time reasonably request to better assure, preserve, protect and
perfect the Security Interest and the rights and remedies created hereby,
including the payment of any fees and taxes required in connection with the
execution and delivery of this Agreement, the granting of the Security Interest
and the filing of any financing statements (including fixture filings) or other
documents in connection herewith or therewith. If any amount payable under or in
connection with any of the Collateral shall be or become evidenced by any
promissory note or other instrument, such note or instrument shall be
immediately pledged and delivered to the Secured Parties, duly endorsed in a
manner satisfactory to the Secured Parties.

     Section 5.2. POWER OF ATTORNEY.

            (a)  Grantor hereby irrevocably (as a power coupled with an
interest) constitutes and appoints the Secured Parties (and all officers,
employees or agents designated by the Secured Parties), its attorney-in-fact
with full power of substitution, for the benefit of the Secured Parties,

                 (i) to take all appropriate action and to execute all documents
     and instruments that may be necessary or desirable to accomplish the
     purposes of this Agreement, and without limiting the generality of the
     foregoing, Grantor hereby grants the power to file one or more financing
     statements (including fixture filings), continuation statements, filings
     with the United States Patent and Trademark Office or United States
     Copyright Office (or any successor office or any similar office in any
     other country) or other documents for the purpose of perfecting,
     confirming, continuing, enforcing or protecting the Security Interest
     granted by Grantor, without the signature of Grantor, and naming Grantor as
     debtor and the Secured Parties as secured party; and

                 (ii) at any time following the Secured Parties' demand for
     payment of the Notes (i) to receive, endorse, assign and/or deliver any and
     all notes, acceptances, checks, drafts, money orders or other evidences of
     payment relating to the Collateral or any part thereof; (ii) to demand,
     collect, receive payment of, give receipt for and give discharges and
     releases of all or any of the Collateral; (iii) to sign the name of Grantor
     on any invoice or bill of lading relating to any of the Collateral; (iv) to
     send verifications of accounts to any account debtor or any other Person
     liable for an account; (v) to commence and prosecute any and all suits,
     actions or proceedings at law or in equity in any court of competent
     jurisdiction to collect or otherwise realize on all or any of the
     Collateral or to enforce any rights in respect of any Collateral; (vi) to
     settle, compromise, compound, adjust or defend any actions, suits or
     proceeding relating to all or any of the Collateral; and (vii) to use,
     sell, assign, transfer, pledge, make any agreement with respect to or
     otherwise deal with all or any of the Collateral, and to do all other acts
     and things necessary to carry out the purposes of this Agreement, as fully
     and completely as though the Secured Parties were the absolute owner of the
     Collateral for all purposes; PROVIDED, HOWEVER, that nothing herein
     contained shall be construed as requiring or obligating the Secured Parties
     to make any commitment or to make any inquiry as to the nature or
     sufficiency of any payment received by the Secured Parties, or to present
     or file any

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     claim or notice, or to take any action with respect to the Collateral or
     any part thereof or the moneys due or to become due in respect thereof or
     any property covered thereby, and no action taken or omitted to be taken by
     the Secured Parties with respect to the Collateral or any part thereof
     shall give rise to any defense, counterclaim or offset in favor of Grantor
     or to any claim or action against the Secured Parties.

            (b)  The provisions of this Article shall in no event relieve
Grantor of any of its obligations hereunder with respect to the Collateral or
any part thereof or impose any obligation on the Secured Parties to proceed in
any particular manner with respect to the Collateral or any part thereof, or in
any way limit the exercise by the Secured Parties of any other or further right
which it may have on the date of this Agreement or hereafter, whether hereunder,
by law or otherwise.

                              ARTICLE VI. REMEDIES

     Section 6.1. REMEDIES UPON DEFAULT.

            (a)  Upon the occurrence and during the continuance of an Event of
     Default, Grantor agrees to deliver each item of its Collateral to the
     Secured Parties on demand, and it is agreed that the Secured Parties shall
     have the right to take any of or all the following actions at the same or
     different times (but at all times subject to any Existing Liens): with or
     without legal process and with or without prior notice or demand for
     performance, to take possession of the Collateral and without liability for
     trespass to enter any premises where the Collateral may be located for the
     purpose of taking possession of or removing the Collateral, exercise
     Grantor's right to bill and receive payment for completed work and,
     generally, to exercise any and all rights afforded to a secured party under
     the Uniform Commercial Code or other applicable law. Without limiting the
     generality of the foregoing, Grantor agrees that the Secured Parties shall
     have the right, subject to the mandatory requirements of applicable law, to
     sell or otherwise dispose of all or any part of the Collateral, at public
     or private sale or at any broker's board or on any securities exchange, for
     cash, upon credit or for future delivery as the Secured Parties shall deem
     appropriate. The Secured Parties shall be authorized at any such sale (if
     it deems it advisable to do so) to restrict the prospective bidders or
     purchasers to persons who will represent and agree that they are purchasing
     the Collateral for their own account for investment and not with a view to
     the distribution or sale thereof, and upon consummation of any such sale
     the Secured Parties shall have the right to assign, transfer and deliver to
     the purchaser or purchasers thereof the Collateral so sold. Each such
     purchaser at any such sale shall hold the property sold absolutely, free
     from any claim or right on the part of Grantor, and Grantor hereby waives
     (to the extent permitted by law) all rights of redemption, stay and
     appraisal which Grantor now has or may at any time in the future have under
     any rule of law or statute now existing or hereafter enacted.

            (b)  The Secured Parties shall give Grantor ten (10) days' written
     notice (which Grantor agrees is reasonable notice within the meaning of
     Section 9-504(3) of the Uniform Commercial Code) of the Secured Parties'
     intention to make any sale of Collateral. Such notice, in the case of a
     public sale, shall state the time and place for such sale and, in the case
     of a sale at a broker's board or on a securities exchange, shall state the
     board or exchange at which such sale is to be made and the day on which the

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     Collateral, or portion thereof, will first be offered for sale at such
     board or exchange. Any such public sale shall be held at such time or times
     within ordinary business hours and at such place or places as the Secured
     Parties may fix and state in the notice (if any) of such sale. At any such
     sale, the Collateral, or portion thereof, to be sold may be sold in one lot
     as an entirety or in separate parcels, as the Secured Parties may (in their
     sole and absolute discretion) determine. The Secured Parties shall not be
     obligated to make any sale of any Collateral if it shall determine not to
     do so, regardless of the fact that notice of sale of such Collateral shall
     have been given. The Secured Parties may, without notice or publication,
     adjourn any public or private sale or cause the same to be adjourned from
     time to time by announcement at the time and place fixed for sale, and such
     sale may, without further notice, be made at the time and place to which
     the same was so adjourned. In case any sale of all or any part of the
     Collateral is made on credit or for future delivery, the Collateral so sold
     may be retained by the Secured Parties until the sale price is paid by the
     purchaser or purchasers thereof, but the Secured Parties shall not incur
     any liability in case any such purchaser or purchasers shall fail to take
     up and pay for the Collateral so sold and, in case of any such failure,
     such Collateral may be sold again upon like notice. At any public (or, to
     the extent permitted by law, private) sale made pursuant to this Section,
     the Secured Parties may bid for or purchase, free (to the extent permitted
     by law) from any right of redemption, stay, valuation or appraisal on the
     part of Grantor (all said rights being also hereby waived and released to
     the extent permitted by law), the Collateral or any part thereof offered
     for sale and may make payment on account thereof by using any claim then
     due and payable to the Secured Parties from Grantor as a credit against the
     purchase price, and the Secured Parties may, upon compliance with the terms
     of sale, hold, retain and dispose of such property without further
     accountability to Grantor therefor. For purposes hereof, a written
     agreement to purchase the Collateral or any portion thereof shall be
     treated as a sale thereof; the Secured Parties shall be free to carry out
     such sale pursuant to such agreement and Grantor shall not be entitled to
     the return of the Collateral or any portion thereof subject thereto,
     notwithstanding the fact that after the Secured Parties shall have entered
     into such an agreement all Obligations have been paid in full. As an
     alternative to exercising the power of sale herein conferred upon it, the
     Secured Parties may proceed by a suit or suits at law or in equity to
     foreclose this Agreement and to sell the Collateral or any portion thereof
     pursuant to a judgment or decree of a court or courts having competent
     jurisdiction or pursuant to a proceeding by a court-appointed receiver.

     Section 6.2. APPLICATION OF PROCEEDS. The Secured Parties shall apply the
proceeds of any collection or sale of the Collateral, as well as any Collateral
consisting of cash, as follows:

            (a)  FIRST, to the payment of all costs and expenses incurred by the
Secured Parties in connection with such collection or sale or otherwise in
connection with this Agreement or any of the Obligations, including all court
costs and the fees and expenses of its agents and legal counsel, and any other
costs or expenses incurred in connection with the exercise of any right or
remedy hereunder, under the Purchase Agreement, the Notes and the other
Transaction Documents;

            (b)  SECOND, to the payment in full of the Obligations; and

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            (c)  THIRD, to Grantor, its successors or assigns, or to whomsoever
may be lawfully entitled to receive the same, or as a court of competent
jurisdiction may otherwise direct.

     Subject to the foregoing, the Secured Parties shall have absolute
discretion as to the time of application of such proceeds, moneys or balances in
accordance with this Agreement. Upon any sale of the Collateral by the Secured
Parties (including pursuant to a power of sale granted by statute or under a
judicial proceeding), the receipt of any such proceeds, moneys or balances by
the Secured Parties or of the officer making the sale shall be a sufficient
discharge to the purchaser or purchasers of the Collateral so sold and such
purchaser or purchasers shall not be obligated to see to the application of any
part of the purchase money paid over to the Secured Parties or such officer or
be answerable in any way for the misapplication thereof.

     Section 6.3. GRANT OF LICENSE TO USE INTELLECTUAL PROPERTY. For the purpose
of enabling the Secured Parties to exercise rights and remedies under this
Article at such time as the Secured Parties shall be lawfully entitled to
exercise such rights and remedies, to the extent not prohibited by any
intellectual property license, Grantor hereby grants to the Secured Parties an
irrevocable, non-exclusive license (exercisable without payment of royalty or
other compensation to Grantor) to use, license or sub-license any of the
Collateral consisting of intellectual property now owned or hereafter acquired
by Grantor, and wherever the same may be located, and including in such license
reasonable access to all media in which any of the licensed items may be
recorded or stored and to all computer software and programs used for the
compilation or printout thereof. The use of such license by the Secured Parties
may be exercised, at the option of the Secured Parties, only following the
Secured Parties' demand for payment of the Notes.

                           ARTICLE VII. MISCELLANEOUS

     Section 7.1. NOTICES. All communications and notices hereunder to the
Grantor and to the Secured Parties shall (except as otherwise expressly
permitted herein) be in writing and delivered to the Grantor or the Secured
Parties, as the case may be, as provided in the Purchase Agreement.

     Section 7.2. SECURITY INTEREST ABSOLUTE. All rights of the Secured Parties
hereunder, the Security Interest and all obligations of Grantor hereunder shall
be absolute and unconditional irrespective of (a) any lack of validity or
enforceability of the Purchase Agreement, the Notes, any Loan Document or any
agreement with respect to any of the Obligations or any other agreement or
instrument relating to any of the foregoing, (b) any change in the time, manner
or place of payment of, or in any other term of, all or any of the Obligations,
or any other amendment or waiver of or any consent to any departure from the
Purchase Agreement, the Notes, any Loan Document or any other agreement or
instrument, (c) any exchange, release or non-perfection of any Lien on other
collateral, or any release or amendment or waiver of or consent under or
departure from any guarantee, securing or guaranteeing all or any of the
Obligations, or (d) any other circumstance that might otherwise constitute a
defense available to, or a discharge of, Grantor in respect of the Obligations
or this Agreement.

     Section 7.3. SURVIVAL OF AGREEMENT. All covenants, agreements,
representations and warranties made by Grantor herein and in the certificates or
other instruments prepared or delivered in connection with or pursuant to this
Agreement shall be considered to have been

<Page>

                                                                              11

relied upon by the Secured Parties and shall survive the making of the loan and
the execution and delivery to the Secured Parties of the Notes, regardless of
any investigation made by the Secured Parties or on their behalf; and shall
continue in full force and effect until this Agreement shall terminate.

     Section 7.4. BINDING EFFECT; SEVERAL AGREEMENT; SUCCESSORS AND ASSIGNS.
This Agreement shall become effective as to Grantor when a counterpart hereof
executed on behalf of Grantor shall have been delivered to the Secured Parties
and a counterpart hereof shall have been executed on behalf of the Secured
Parties, and thereafter shall be binding upon Grantor and the Secured Parties
and their respective successors and assigns, and shall inure to the benefit of
Grantor, the Secured Parties and their respective successors and assigns, except
that Grantor shall not have the right to assign or transfer its rights or
obligations hereunder or any interest herein or in the Collateral (and any such
assignment or transfer shall be void) except as expressly contemplated by this
Agreement, the Purchase Agreement, the Notes or the other Transaction Documents.

     Section 7.5. SECURED PARTIES' FEES AND EXPENSE; INDEMNIFICATION.

            (a)  Grantor agrees to pay upon demand to the Secured Parties the
     amount of any and all reasonable expenses, including all reasonable fees,
     disbursements and other charges of its counsel and of any experts or
     agents, which the Secured Parties may incur in connection with (i) the
     administration of this Agreement (including the customary fees and charges
     of the Secured Parties for any audits conducted by them or on their behalf
     with respect to the accounts inventory), (ii) the custody or preservation
     of, or the sale of, collection from or other realization upon any of the
     Collateral, (iii) the exercise, enforcement or protection of any of the
     rights of the Secured Parties hereunder or (iv) the failure of Grantor to
     perform or observe any of the provisions hereof.

            (b)  Grantor agrees to indemnify the Secured Parties and the agent,
     contractors and employees of the Secured Parties (collectively, the
     "INDEMNITEES") against, and hold each of them harmless from, any and all
     losses, claims, damages, liabilities and related expenses, including
     reasonable fees, disbursements and other charges of counsel, incurred by or
     asserted against any of them arising out of, in any way connected with, or
     as a result of, the execution, delivery, or performance of this Agreement
     or any agreement or instrument contemplated hereby or any claim,
     litigation, investigation or proceeding relating hereto or to the
     Collateral, whether or not any Indemnitee is a party thereto; provided that
     such indemnity shall not, as to any Indemnitee, be available to the extent
     that such losses, claims, damages, liabilities or related expenses are
     determined by a court of competent jurisdiction by final and nonappealable
     judgment to have resulted from the gross negligence or willful misconduct
     of such Indemnitee.

            (c)  Any such amounts payable as provided hereunder shall be
     additional Obligations secured hereby. The provisions of this Section shall
     remain operative and in full force and effect regardless of the termination
     of this Agreement, the Purchase Agreement, the Notes or the other
     Transaction Documents, the consummation of the transactions contemplated
     hereby, the repayment of any of the Obligations, the invalidity or
     unenforceability of any term or provision of this Agreement, the Purchase
     Agreement,

<Page>

                                                                              12

     the Notes or the other Transaction Documents, or any investigation made by
     or on behalf of the Secured Parties. All amounts due under this Section
     shall be payable on written demand therefor.

     Section 7.6. GOVERNING LAW. THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE
WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK.

     Section 7.7. WAIVERS; AMENDMENT.

            (a)  No failure or delay of the Secured Parties in exercising any
power or right hereunder shall operate as a waiver thereof, nor shall any single
or partial exercise of any such right or power, or any abandonment or
discontinuance of steps to enforce such a right or power, preclude any other or
further exercise thereof or the exercise of any other right or power. The rights
and remedies of the Secured Parties hereunder and under the Purchase Agreement
are cumulative and are not exclusive of any rights or remedies that they would
otherwise have. No waiver of any provisions of this Agreement, the Purchase
Agreement, the Notes or the other Transaction Documents or consent to any
departure by Grantor therefrom shall in any event be effective unless the same
shall be permitted by paragraph (b) below, and then such waiver or consent shall
be effective only in the specific instance and for the purpose for which given.
No notice to or demand on Grantor in any case shall entitle Grantor to any other
or further notice or demand in similar or other circumstances.

            (b)  Neither this Agreement nor any provision hereof may be waived,
amended or modified except pursuant to an agreement or agreements, in writing
entered into by the Secured Parties and Grantor.

     Section 7.8. WAIVER OF JURY TRIAL. EACH PARTY HERETO HEREBY WAIVES, TO THE
FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY
JURY IN RESPECT OF ANY LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF, UNDER
OR IN CONNECTION WITH THIS AGREEMENT, THE PURCHASE AGREEMENT OR THE NOTES. EACH
PARTY HERETO (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY
OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD
NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER AND (B)
ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED TO ENTER
INTO THIS AGREEMENT, THE PURCHASE AGREEMENT AND THE NOTES, AS APPLICABLE, BY,
AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION.

     Section 7.9. SEVERABILITY. In the event any one or more of the provisions
contained in this Agreement should be held invalid, illegal or unenforceable in
any respect, the validity, legality and enforceability of the remaining
provisions contained herein shall not in any way be affected or impaired thereby
(it being understood that the invalidity of a particular provision in a
particular jurisdiction shall not in and of itself affect the validity of such
provision in any other jurisdiction). The parties shall endeavor in good-faith
negotiations to replace the invalid, illegal or unenforceable provisions with
valid provisions the economic effect of which comes as close as possible to that
of the invalid, illegal or unenforceable provisions.

<Page>

                                                                              13

     Section 7.10. COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall constitute an original but all of which when
taken together shall constitute but one contract. Each party shall be entitled
to rely on a facsimile signature of any other party hereunder as if it were an
original.

     Section 7.11. JURISDICTION; CONSENT TO SERVICE OF PROCESS.

            (a)  Grantor hereby irrevocably and unconditionally submits, for
     itself and its property, to the nonexclusive jurisdiction of any New York
     State court or Federal court of the United States of America sitting in New
     York City, and any appellate court from any thereof, in any action or
     proceeding arising out of or relating to this Agreement, the Purchase
     Agreement or the Notes, or for recognition or enforcement of any judgment,
     and each of the parties hereto hereby irrevocably and unconditionally
     agrees that all claims in respect of any such action or proceeding may be
     heard and determined in such New York State or, to the extent permitted by
     law, in such Federal court. Each of the parties hereto agrees that a final
     judgment in any such action or proceeding shall be conclusive and may be
     enforced in other jurisdictions by suit on the judgment or in any other
     manner provided by law. Nothing in this Agreement shall affect any right
     that the Secured Parties may otherwise have to bring any action or
     proceeding relating to this Agreement, the Purchase Agreement, the Notes or
     the other Transaction Documents against Grantor or its properties in the
     courts of any jurisdiction.

            (b) Grantor hereby irrevocably and unconditionally waives, to the
     fullest extent it may legally and effectively do so, any objection which it
     may now or hereafter have to the laying of venue of any suit, action or
     proceeding arising out of or relating to this Agreement, the Purchase
     Agreement, the Notes or the other Transaction Documents in any New York
     State or Federal court. Each of the parties hereto hereby irrevocably
     waives, to the fullest extent permitted by law, the defense of an
     inconvenient forum to the maintenance of such action or proceeding in any
     such court.

            (c) Each party to this Agreement irrevocably consents to service of
     process in the manner provided for notices in Section 7.1. Nothing in this
     Agreement will affect the right of any party to this Agreement to process
     in any other manner permitted by law.

     Section 7.12. TERMINATION. This Agreement and the Security Interest shall
terminate when all the Obligations have been paid in full, at which time the
Secured Parties shall execute and deliver to Grantor, at Grantor's expense, all
Uniform Commercial Code termination statements and similar documents which
Grantor shall reasonably request to evidence such termination. Any execution and
delivery of termination statements or documents pursuant to this Section shall
be without recourse to or warranty by the Secured Parties.

     Section 7.13. PREJUDGMENT REMEDY WAIVER. Grantor acknowledges that this
Agreement, the Purchase Agreement, the Notes and the other Transaction Documents
evidence a commercial transaction and that it could, under certain circumstances
have the right, to notice of and hearing on the right of the Secured Parties to
obtain a prejudgment remedy, such as attachment, garnishment and/or replevin,
upon commencing any litigation against Grantor. Notwithstanding, Grantor hereby
waives all rights to notice, judicial hearing or prior court order to which it
might otherwise have the right under any state or federal statute or
constitution in connection with the

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                                                                              14

obtaining by the Secured Parties of any prejudgment remedy by reason of this
Agreement, the Purchase Agreement, the Notes, the other Transaction Documents or
by reason of the Obligations or any renewals or extensions of the same. Grantor
also waives any and all objection which it might otherwise assert, now or in the
future, to the exercise or use by the Secured Parties of any right of setoff,
repossession or self help as may presently exist under statute or common law.

                            [SIGNATURE PAGE FOLLOWS]

<Page>

     IN WITNESS WHEREOF, the parties have duly executed this Security Agreement
as of the day and year first written above.


                                            SATCON TECHNOLOGY CORPORATION


                                            By: /s/ Ralph M. Norwood
                                                --------------------------------
                                                  Name: Ralph M. Norwood
                                                  Title: Vice-Pres. & CFO



                                            SECURED PARTY

                                            DMG LEGACY FUND LLC

                                            By: /s/ Andrew Wilder
                                                --------------------------------
                                                  Name: Andrew Wilder
                                                  Title: Chief Financial Officer



                                            SECURED PARTY

                                            DMG LEGACY INSTITUTIONAL FUND LLC

                                            By: /s/ Andrew Wilder
                                                --------------------------------
                                                  Name: Andrew Wilder
                                                  Title: Chief Financial Officer


                                            SECURED PARTY

                                            DMG LEGACY INTERNATIONAL LTD.

                                            By: /s/ Andrew Wilder
                                                --------------------------------
                                                  Name: Andrew Wilder
                                                  Title: Chief Financial Officer


                                            PURCHASER

                                            SDS MERCHANT FUND, LP

                                            By: /s/ Scott Derby
                                                --------------------------------
                                                  Name: Scott E. Derby
                                                  Title: General Counsel



                                            PURCHASER

                                            OTAPE LLC

                                            By: /s/ Richard M. Coyne
                                                --------------------------------
                                                  Name: Richard M. Coyne
                                                  Title: General Counsel



                                            PURCHASER


                                            By: /s/ Gregory Porges
                                                --------------------------------
                                                  Name: Gregory Porges
                                                  Title: President of the
                                                         General Partner



                                            PURCHASER

                                            Crestview Capital Fund I, LP

                                            By: /s/ Richard Levy
                                                --------------------------------
                                                  Name: Richard Levy
                                                  Title: Managing Member


                                            PURCHASER

                                            Crestview Capital Fund II, LP

                                            By: /s/ Richard Levy
                                                --------------------------------
                                                  Name: Richard Levy
                                                  Title: Managing Member


                                            PURCHASER

                                            Crestview Capital Offshore
                                            Fund Inc.

                                            By: /s/ Richard Levy
                                                --------------------------------
                                                  Name: Richard Levy
                                                  Title: Secretary


                                            PURCHASER

                                            RHP Master Fund, Ltd.
                                            By: Rock Hill Investment
                                            Management, L.P.
                                            By: RHP General Partner, LLC

                                            By: /s/ Wayne D. Bloch
                                               --------------------------------
                                                 Name: Wayne D. Bloch
                                                 Title: Its Managing Partner






<Page>

                                    EXHIBIT A
                                 SECURED PARTIES

OTAPE LLC
One Manhattanville Rd.
Purchase, N.Y. 10527
Attention: Paul Masters
Fax No.: (914) 694-6335

MRT, L.P.
120 Broadway, Suite 1050
New York, NY 10271
Attention: Ian Estepan
Fax No.: (212) 433-6188

Crestview Capital Fund I
95 Revere Dr., Suite F
Northbrook, IL 60062
Attention: Richard Levy
Fax No.: (847) 559-5807

Crestview Capital Fund II
95 Revere Dr., Suite F
Northbrook, IL 60062
Attention: Richard Levy
Fax No.: (847) 559-5807

Crestview Capital Offshore Inc.
95 Revere Dr., Suite F
Northbrook, IL 60062
Attention: Richard Levy
Fax No.: (847) 559-5807

RHP Master Fund, Ltd.
c/o Rock Hill Investment
Management, L.P.
Three Bala Plaza-East, Suite 585
Cynwyd, PA 19004
Attention: Keith Marlowe
Fax No.: (610) 949-9600

DMG Legacy Fund LLC
c/o DMG Advisors LLC
53 Forest Avenue, Second Floor
Old Greenwich, CT 06870

<Page>

                                                                              17

Attention: Andrew Wilder
Fax No.: (203) 967-5851

DMG Legacy Institutional Fund Ltd.
c/o DMG Advisors LLC
53 Forest Avenue, Second Floor
Old Greenwich, CT 06870
Attention: Andrew Wilder
Fax No.: (203) 967-5851

DMG Legacy International Ltd.
c/o DMG Advisors LLC
53 Forest Avenue, Second Floor
Old Greenwich, CT 06870
Attention: Andrew Wilder
Fax No.: (203) 967-5851

SDS Merchant Fund, L.P.
c/o SDS Capital Partners, LLC
53 Forest Avenue, Second Floor
Old Greenwich, CT 06870
Attention: Steve Derby
Fax No.: (203) 967-5880

<Page>

                                                                              18

                                   SCHEDULE A

          PLACES OF BUSINESS; CHIEF EXECUTIVE OFFICE; FILING LOCATIONS

STATE OF INCORPORATION:
Delaware

CHIEF EXECUTIVE OFFICE:
161 First Street
Cambridge, MA 02142

FILING LOCATIONS:
Secretary of State of the State of Delaware

<Page>

                                                                              19

                                  SCHEDULE 3.3
                                 EXISTING LIENS

Silicon Valley Bank holds a blanket security interest in all of the Grantor's
assets pursuant to the Loan and Security Agreement dated September 13, 2002 by
and between the Grantor and Silicon Valley Bank, as amended.

<Page>

                                                                              20

                                  SCHEDULE 3.4
                             ABSENCE OF OTHER LIENS

Silicon Valley Bank holds a blanket security interest in all of the Grantor's
assets pursuant to the Loan and Security Agreement dated September 13, 2002 by
and between the Grantor and Silicon Valley Bank, as amended.