<PAGE>

                                                                 Exhibit 10.43

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED OR ANY APPLICABLE STATE SECURITIES LAWS,
AND MAY NOT BE SOLD, PLEDGED, OR OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE
REGISTRATION THEREOF UNDER SUCH ACT AND LAWS, OR PURSUANT TO RULE 144 AND AN
EXEMPTION UNDER APPLICABLE STATE SECURITIES LAWS, OR AN OPINION OF COUNSEL
REASONABLY SATISFACTORY TO THE CORPORATION AND ITS COUNSEL, THAT SUCH
REGISTRATION IS NOT REQUIRED.


                            WARRANT TO PURCHASE STOCK

Issuer:  SatCon Technology Corporation, a Delaware corporation
Number of Shares: 15,763, subject to adjustment
Class of Stock: Common Stock, $0.01 par value per share
Exercise Price: $1.586, subject to adjustment
Issue Date:  December 19, 2002
Expiration Date:  December 18, 2007

         THIS WARRANT CERTIFIES THAT, for the agreed upon value of $1.00 and for
other good and valuable consideration, this Warrant is issued to SILICON VALLEY
BANK by SatCon Technology Corporation, a Delaware corporation (the "Company").
Silicon Valley Bank and/or its registered assigns are referred to hereinafter as
"Holder."

         Subject to the terms and conditions hereinafter set forth, the Holder
is entitled upon surrender of this Warrant and the duly executed subscription
form annexed hereto as Appendix 1, at the office of the Company, 161 First
Street, Cambridge, Massachusetts 02142-1221 or such other office as the Company
shall notify the Holder of in writing, to purchase from the Company up to
Fifteen Thousand Seven Hundred Sixty-three (15,763) fully paid and
non-assessable shares (the "Shares") of the Company's common stock, $0.01 par
value per share ("Common Stock") at a purchase price per Share of $1.586 (the
"Exercise Price"). This Warrant may be exercised in whole or in part at any time
and from time to time until 5:00 PM, Eastern time, on the Expiration Date, and
shall be void thereafter. Until such time as this Warrant is exercised in full
or expires, the Exercise Price and the Shares are subject to adjustment from
time to time as hereinafter provided.

ARTICLE 1. EXERCISE.

         1.1 METHOD OF EXERCISE. Holder may exercise this Warrant by
surrendering this Warrant to the Company together with a duly executed Notice of
Exercise in substantially the form attached as APPENDIX 1 to the principal
office of the


<PAGE>

Company. Unless Holder is exercising the cashless exercise right
set forth in Section 1.2, Holder shall also deliver to the Company a check for
the aggregate Exercise Price for the Shares being purchased.

         1.2 CASHLESS EXERCISE. Holder may, at is option, elect to pay some or
all of the Exercise Price payable upon any exercise of this Warrant by
cancelling a portion of this Warrant exercisable for such number of Shares as is
determined by dividing (i) the aggregate Exercise Price payable in respect of
the number of Shares being purchased upon such exercise by (ii) the excess of
the Fair Market Value (as defined) below of one Share as of the Exercise Date
(defined below) over the Exercise Price per Share. If Holder wishes to exercise
this Warrant pursuant to such cashless payment method with respect to the
maximum number of Shares purchasable pursuant to such method, then the number of
Shares so issuable to shall equal the total number of Shares then purchasable
under this Warrant, minus the product obtained by multiplying (x) such total
number of Shares by (y) a fraction, the numerator of which shall be the Exercise
Price per Share and the denominator of which shall be the Fair Market Value of
one Share as of the Exercise Date.

         1.3 EXERCISE; DELIVERY OF SHARES. As soon as practicable following any
exercise of this Warrant in whole or in part, and in any event within ten (10)
days thereafter, the Company, at its expense, will cause to be issued in the
name of, and delivered to, Holder, or as Holder (upon payment of any applicable
transfer taxes) may direct:

              (i) a certificate or certificates representing the number of full
Shares as to which Holder shall have exercised this Warrant plus, in lieu of any
fractional Share to which Holder would otherwise be entitled, cash in an amount
determined pursuant to Section 2.6 below; and

              (ii) in case such exercise is in part only, a new warrant or
warrants (dated as of the date hereof) of like tenor, calling in the aggregate
on the face or faces thereof for the number of Shares equal (without giving
effect to any adjustment therein) to the number of such Shares called for on the
face of this Warrant minus the sum of (a) the number of such Shares purchased by
Holder upon such exercise plus (b) the number of Shares (if any) covered by the
portion of this Warrant cancelled in payment of the Exercise Price payable upon
exercise pursuant to Section 1.2 above.

         1.4 FAIR MARKET VALUE. The Fair Market Value of one Share shall be
determined as follows:

              1.4.1 If shares of Common Stock are traded on a nationally
recognized securities exchange or over the counter market, the fair market value
of one Share shall be the closing price of a share of Common Stock reported for
the business day


<PAGE>

immediately preceding the date of Holder's Notice of Exercise to the Company
(the "Exercise Date").

              1.4.2 If shares of Common Stock are not traded on a nationally
recognized securities exchange or over the counter market, the Board of
Directors of the Company shall determine the fair market value of a share of
Common Stock in its reasonable good faith judgment.

         1.5 DELIVERY OF CERTIFICATE AND NEW WARRANT. Promptly after Holder
exercises or converts this Warrant, the Company promptly shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new warrant of like tenor
representing the right to purchase the Shares not so acquired.

         1.6 REPLACEMENT OF WARRANTS. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
(with surety if reasonably required) or, in the case of mutilation, on surrender
and cancellation of this Warrant, the Company at its expense shall execute and
deliver, in lieu of this Warrant, a new warrant of like tenor.

         1.7 ASSUMPTION ON SALE, MERGER, OR CONSOLIDATION OF THE COMPANY.

              1.7.1. "ACQUISITION". For the purpose of this Warrant,
"Acquisition" means any sale, transfer, exclusive license, or other disposition
of all or substantially all of the assets of the Company ("Asset Sale"), or any
acquisition, reorganization, consolidation or merger of the Company where the
holders of the Company's outstanding voting equity securities immediately prior
to the transaction beneficially own less than 50.01% of the outstanding voting
equity securities of the surviving or successor entity immediately following the
transaction.

              1.7.2. ASSUMPTION OF WARRANT. In connection with, and upon the
closing of, any Acquisition (other than an Acquisition in which the
consideration received by the Company's stockholders consists solely of cash),
and as a condition precedent thereto, the successor or surviving entity shall
assume the obligations of this Warrant, and this Warrant thereafter shall be
exercisable for the same kind and amount of securities and other property as
would be payable for the Shares issuable upon exercise of the unexercised
portion of this Warrant as if such Shares were outstanding on the record date
for the Acquisition and subsequent closing. The Exercise Price shall be adjusted
such that the product of (i) the Exercise Price in effect immediately prior to
the closing of such Acquisition, and (ii) the number of Shares then issuable
upon exercise of this Warrant, equals the product of (i) the number of shares or
other securities or property for which this


                                      -3-

<PAGE>

Warrant shall be exercisable immediately following the closing of such
Acquisition, and (ii) the Exercise Price in effect immediately following the
closing of such Acquisition, and the Exercise Price and number and class of
Shares shall continue to be subject to adjustment from time to time in
accordance with the provisions hereof.

              1.7.3 ASSET SALES. Notwithstanding the provisions of Section 1.7.2
above, in the event of any Asset Sale, the Company shall use its reasonable best
efforts to effect the assumption of this Warrant at the closing thereof by the
buyer(s) or other transferee(s). If, notwithstanding such reasonable best
efforts by the Company, the buyer(s) or other transferee(s) notify the Company
in writing that it or they are unwilling to assume this Warrant, then the
Company shall promptly notify the Holder of such determination, and Holder
thereafter shall have the right, subject to the terms hereof, to exercise this
Warrant in connection with such Asset Sale either at or before the closing
thereof or at such later date, prior to any distribution by the Company to its
stockholders of proceeds received in such Asset Sale, or to continue to hold
this Warrant until the Expiration Date hereof if the Company continues as a
going concern following the closing of such Asset Sale.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

         2.1 STOCK DIVIDENDS, SPLITS, ETC. If the Company declares or pays a
dividend on the outstanding shares of Common Stock, payable in Common Stock or
other securities of the Company, or subdivides the outstanding Common Stock into
a greater amount of Common Stock, then upon exercise of this Warrant, for each
Share acquired, Holder shall receive, without cost to Holder, the total number
and kind of securities to which Holder would have been entitled had Holder owned
the Shares of record as of the date the dividend or subdivision occurred.

         2.2 RECLASSIFICATION, EXCHANGE OR SUBSTITUTION. Upon any
reclassification, exchange, substitution, or other event that results in a
change of the number and/or class of the securities issuable upon exercise or
conversion of this Warrant, Holder shall be entitled to receive, upon exercise
or conversion of this Warrant, the number and kind of securities and property
that Holder would have received for the Shares if this Warrant had been
exercised immediately before such reclassification, exchange, substitution, or
other event. Upon the return of this Warrant for cancellation by the Company,
the Company or its successor shall promptly issue to Holder a new Warrant for
such new securities or other property. The new Warrant shall provide for
adjustments which shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Article 2 including, without limitation,
adjustments to the Exercise Price and to the number of securities or property
issuable upon exercise of the new Warrant. The provisions of this Section 2.2
shall similarly apply to successive reclassifications, exchanges, substitutions,
or other events.


                                      -4-

<PAGE>

         2.3 ADJUSTMENTS FOR COMBINATIONS, ETC. If the outstanding shares of
Common Stock are combined or consolidated, by reclassification or otherwise,
into a lesser number of shares, the Exercise Price shall be proportionately
increased and the number of Shares shall be proportionately decreased.

         2.4 NO IMPAIRMENT. The Company shall not, by amendment of its
Certificate of Incorporation or by-laws, or through a reorganization, transfer
of assets, consolidation, merger, dissolution, issue, or sale of securities or
any other voluntary action, avoid or seek to avoid the observance or performance
of any of the terms to be observed or performed under this Warrant by the
Company, but shall at all times in good faith assist in carrying out of all the
provisions of this Article 2 and in taking all such action as may be necessary
or appropriate to protect Holder's rights under this Article against impairment.

         2.5 INTENTIONALLY OMITTED.

         2.6 FRACTIONAL SHARES. No fractional Shares shall be issuable upon
exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded down to the nearest whole Share. If a fractional Share interest
arises upon any exercise or conversion of this Warrant, the Company shall
eliminate such fractional Share interest by paying Holder an amount computed by
multiplying such fractional interest by the Fair Market Value (determined in
accordance with Section 1.4 above) of one Share.

         2.7 CERTIFICATE AS TO ADJUSTMENTS. Upon each adjustment of the Exercise
Price, number of Shares or class of security for which this Warrant is
exercisable, the Company at its expense shall promptly compute such adjustment,
and furnish Holder with a certificate of its chief financial or other officer
setting forth such adjustment and the facts upon which such adjustment is based.
The Company shall, upon written request, furnish Holder a certificate setting
forth the Exercise Price, number of Shares and class of security for which this
Warrant is exercisable in effect upon the date thereof and the series of
adjustments leading to such Exercise Price, number of Shares and class of
security.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

         3.1 REPRESENTATIONS AND WARRANTIES. The Company hereby represents and
warrants to the Holder as follows:

              (a) All Shares which may be issued upon the due exercise of this
Warrant shall, upon issuance, be duly authorized, validly issued, fully paid and
non-assessable, and free of any liens and encumbrances except for restrictions
on transfer provided for herein or under applicable federal and state securities
laws.


                                      -5-

<PAGE>

              (b) The Company covenants that it shall at all times cause to be
reserved and kept available out of its authorized and unissued shares such
number of shares of its Common Stock and other securities as will be sufficient
to permit the exercise in full of this Warrant and the conversion or exchange of
such Common Stock into or for such other securities.

         3.2 NOTICE OF CERTAIN EVENTS. If the Company proposes at any time (a)
to declare any dividend or distribution upon its Common Stock, whether in cash,
property, stock, or other securities and whether or not a regular cash dividend;
(b) to offer for subscription pro rata to the holders of Common Stock any
additional shares of stock of any class or series or other rights; (c) to effect
any reclassification or recapitalization of its Common Stock (d) to merge or
consolidate with or into any other corporation, or sell, lease, license, or
convey all or substantially all of its assets, or to liquidate, dissolve or wind
up; or (e) offer holders of registration rights the opportunity to participate
in an underwritten public offering of the Company's securities for cash, then,
in connection with each such event, the Company shall give Holder (1) at least
10 days prior written notice of the date on which a record will be taken for
such dividend, distribution, or subscription rights (and specifying the date on
which the holders of Common Stock shall be entitled to receive such dividend,
distribution or rights) or for determining rights to vote, if any, in respect of
the matters referred to in (c) and (d) above; (2) in the case of the matters
referred to in (c) and (d) above at least 10 days prior written notice of the
date when the same will take place (and specifying the date on which the holders
of securities of the Company will be entitled to exchange their securities of
the Company for securities or other property deliverable upon the occurrence of
such event); and (3) in the case of the matter referred to in (e) above, the
same notice as is given to the holders of such registration rights.

         3.4 REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED. The Shares
shall have certain "piggy-back" registration rights as set forth in that certain
Registration Rights Agreement between the Company and Holder dated as of
September 13, 2002, pursuant to an amendment thereto to be executed between the
Company, Holder and Silicon Valley Bancshares. The Company represents and
warrants to Holder that the Company's foregoing grant of registration rights and
its execution, delivery and performance of such amendment to Registration Rights
Agreement (a) has been duly authorized by all necessary corporate action of the
Company's Board of Directors and shareholders, (b) does not and will not violate
the Company's Certificate of Incorporation or By-laws, each as amended, (c) does
not and will not violate or cause a breach or default (or an event which with
the passage of time or the giving of notice or both, would constitute a breach
or default) under any agreement, instrument, mortgage, deed of trust or other
arrangement to which the Company is a party or to or by which it or any of its
assets is subject or bound, and (d) does not require the approval, consent or
waiver of or by any shareholder, registration rights holder or other third party
which approval, consent or waiver has not been obtained as of the date of
issuance of this Warrant.


                                      -6-

<PAGE>

ARTICLE 4. REPRESENTATIONS AND WARRANTIES OF THE HOLDER.

         4.1 PURCHASE FOR OWN ACCOUNT. Except for transfers to Holder's
affiliates, this Warrant and the Shares to be acquired upon exercise hereof will
be acquired for investment for Holder's account, not as nominee or agent, and
not with a view to sale or distribution in violation of applicable federal and
state securities laws.

         4.2 INVESTMENT EXPERIENCE. Holder understands that the purchase of this
Warrant and the Shares covered hereby involves substantial risk. Holder (a) has
experience as an investor in unregistered securities, (b) has sufficient
knowledge and experience in financial and business affairs that enable it to
evaluate the risks and merits of its investment in this Warrant and the Shares,
and (c) can bear the economic risk of such Holder's investment in this Warrant
and the Shares.

         4.3 ACCREDITED INVESTOR. Holder is an "accredited investor" as such
term is defined in Regulation D under the Securities Act of 1933, as amended.

ARTICLE 5. MISCELLANEOUS.

         5.1 AUTOMATIC CONVERSION UPON EXPIRATION. In the event that, upon the
Expiration Date, the Fair Market Value of one Share (or other security issuable
upon the exercise hereof) as determined in accordance with Section 1.3 above is
greater than the Exercise Price in effect on such date, then this Warrant shall
automatically be deemed on and as of such date to be converted pursuant to
Section 1.2 above as to all Shares (or such other securities) for which it shall
not previously have been exercised or converted, and upon notice to the Company
by Holder, the Company shall promptly deliver a certificate representing the
Shares (or such other securities) issued upon such conversion to the Holder.

         5.2 LEGENDS. This Warrant and the Shares shall be imprinted with a
legend in substantially the following form:

         THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
         AS AMENDED, OR ANY APPLICABLE STATE SECURITIES LAWS, AND MAY NOT BE
         SOLD, PLEDGED OR OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE
         REGISTRATION THEREOF UNDER SUCH ACT AND SUCH LAWS, OR PURSUANT TO RULE
         144 AND AN EXEMPTION FROM APPLICABLE STATE SECURITIES LAWS, OR AN
         OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE CORPORATION AND ITS
         COUNSEL THAT SUCH REGISTRATION IS NOT REQUIRED.


                                      -7-

<PAGE>

         5.3 COMPLIANCE WITH SECURITIES LAWS ON TRANSFER. This Warrant and the
Shares may not be transferred or assigned in whole or in part without compliance
with applicable federal and state securities laws by the transferor and the
transferee (including, without limitation, the delivery of investment
representation letters and legal opinions reasonably satisfactory to the
Company, as reasonably requested by the Company). The Company shall not require
Holder to provide an opinion of counsel if the transfer is to an affiliate of
Holder or if (a) there is no material question as to the availability of current
information as referenced in Rule 144(c), (b) Holder represents that it has
complied with Rule 144(d) and (e) in reasonable detail, (c) the selling broker
represents that it has complied with Rule 144(f), and (d) the Company is
provided with a copy of Holder's notice of proposed sale.

         5.4 TRANSFER PROCEDURE.

              (a) Subject to the provisions of Section 5.3, Holder may transfer
all or part of this Warrant and/or the Shares issuable upon exercise of this
Warrant (or the securities issuable, directly or indirectly, upon conversion of
the Shares, if any) at any time to Silicon Valley Bancshares or The Silicon
Valley Bank Foundation, or, to any other transferee by giving the Company notice
of the portion of the Warrant being transferred setting forth the name, address
and taxpayer identification number of the transferee and surrendering this
Warrant to the Company for reissuance to the transferee(s) (and Holder if
applicable).

              (b) The Company will maintain a register containing the name and
address of the Holder of this Warrant. The Holder may change such address by
written notice to the Company requesting such change.

              (c) Subject to the provisions of Section 5.3 and Section 5.4 (a)
above, this Warrant and all rights hereunder are transferable, in whole or in
part, upon surrender of this warrant with a properly executed assignment (in the
form of APPENDIX 1 hereto) at the principal office of the Company.

              (d) Until any transfer of this Warrant is made in the warrant
register, the Company may treat Holder as the absolute owner hereof for all
purposes; PROVIDED, that if and when this Warrant is properly assigned in blank,
the Company may (but shall not be obligated to) treat the bearer hereof as the
absolute owner hereof for all purposes, notwithstanding any notice to the
contrary.

         5.5 NOTICES. All notices and other communications from the Company to
the Holder, or vice versa, shall be deemed delivered and effective when given
personally or sent by electronic facsimile transmission, express overnight
courier service, or mailed by


                                      -8-

<PAGE>

first-class registered or certified mail, postage prepaid, at such address as
may have been furnished to the Company or the Holder, as the case may be, in
writing by the Company or such Holder from time to time, but in all cases,
unless instructed in writing otherwise, the Company shall deliver a copy of all
notices to Holder to Silicon Valley Bank, Treasury Department, 3003 Tasman
Drive, HA 200, Santa Clara, California 95054.

         5.6 WAIVER. This Warrant and any term hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of such change, waiver, discharge or termination is
sought.

         5.7 ATTORNEYS FEES. In the event of any dispute between the parties
concerning the terms and provisions of this Warrant, the party prevailing in
such dispute shall be entitled to collect from the other party all costs
incurred in such dispute, including reasonable attorneys' fees.

         5.8 GOVERNING LAW. This Warrant shall be governed by and construed in
accordance with the laws of The Commonwealth of Massachusetts, without giving
effect to its principles regarding conflicts of law.

         5.9 NO RIGHTS AS A SHAREHOLDER. Except as specifically provided in this
Warrant, Holder shall have no rights as a shareholder of the Company in respect
of the Shares issuable hereunder unless and until Holder exercises this Warrant
as to all or any of such Shares.


                  [REMAINDER OF PAGE LEFT BLANK INTENTIONALLY]


                                      -9-

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Warrant to Purchase
Stock to be executed as an instrument under seal by its duly authorized
representative as of the date first above written.

ATTEST:                                              "COMPANY"

                                                     SATCON TECHNOLOGY
                                                     CORPORATION



By: /s/ William J. O'Donnell            By: /s/ Ralph M. Norwood
    ----------------------------------      -----------------------------------
Name:  William J. O'Donnell              Name:  Ralph M. Norwood
Title: Director of Corporate             Title: Vice-Pres. & Chief Financial
       Communications                           Officer



                                      -10-

<PAGE>

                                   APPENDIX 1

                               NOTICE OF EXERCISE


         1. The undersigned hereby elects to purchase _______shares of the
____________ stock of __________________ pursuant to Section 1.1 of the attached
Warrant, and tenders herewith payment of the Exercise Price of such shares in
full. The undersigned herewith makes payment of the full purchase price for such
shares at the price per share provided for in such Warrant, which is $_________.
Such payment takes the form of (check all applicable methods):

         ________   $__________ in lawful money of the United States; and/or

         ________   the cancellation of such portion of the attached warrant as
                    is exercisable for a total of ________ Shares (using a Fair
                    Market Value of $______ per Share for purposes of this
                    calculation): and/or

         ________   the cancellation of such number of Shares as is necessary,
                    in accordance with the formula set forth in Section 1.2, to
                    exercise this Warrant with respect to the maximum number of
                    Shares purchasable hereunder, pursuant to the cashless
                    exercise procedure set forth in Section 1.2.

         2. Please issue a certificate or certificates representing said shares
in the name of the undersigned or in such other name as is specified below:


                           -------------------------------------------
                                    (Name)


                           -------------------------------------------

                           -------------------------------------------
                                    (Address)

         3. The undersigned represents it is acquiring the shares solely for its
own account and not as a nominee for any other party and not with a view toward
the resale or distribution thereof except in compliance with applicable
securities laws.

                                           ------------------------------------
                                                         (Signature)

--------------------
       (Date)


<PAGE>


                AMENDMENT NO. 1 TO REGISTRATION RIGHTS AGREEMENT

         THIS AMENDMENT NO. 1 TO REGISTRATION RIGHTS AGREEMENT is made as of
December 19, 2002 by and among Silicon Valley Bank ("Bank"), Silicon Valley
Bancshares ("Bancshares") and SatCon Technology Corporation, a Delaware
corporation (the "Company")

                                    RECITALS

         A. Bank and the Company executed a Registration Rights Agreement dated
as of September 13, 2002 (the "Agreement"). Bank subsequently assigned and
transferred the Agreement and all of its rights and obligations thereunder to
Bancshares.

         B. Concurrently with the execution and delivery of this Amendment No. 1
to the Agreement, the Company is issuing to Bank a Warrant to Purchase Stock
(the "Second Warrant"). Following such issuance, Bank will transfer the Second
Warrant to Holder. Capitalized terms used but not otherwise defined herein shall
have the respective meanings set forth in the Second Warrant.

         C. The parties desire that the Shares issued and issuable upon exercise
or conversion of the Second Warrant (collectively, the "Second Warrant Shares")
be included within the rights granted to Bancshares under the Agreement.

         NOW, THEREFORE, in consideration of the premises and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties agree as follows:

         1. INCLUSION OF SECOND WARRANT SHARES. The term "Registrable
Securities" as defined in the Agreement is hereby amended to include, without
limitation, the Second Warrant Shares and any shares of Common Stock or other
securities or rights to acquire Common Stock or other securities of the Company
issued as a dividend or other distribution on or with respect to, or in exchange
for or replacement of, the Second Warrant Shares.


<PAGE>

         2. COMPANY REPRESENTATIONS AND WARRANTIES. The Company represents and
warrants to Bank and Bancshares that the Company's execution, delivery and
performance of this Amendment No. 1 to the Agreement (a) has been duly
authorized by all necessary corporate action of the Company's Board of Directors
and shareholders, (b) will not violate the Company's Certificate of
Incorporation or By-laws, each as amended, (c) will not violate or cause a
breach or default (or an event which with the passage of time or the giving of
notice or both, would constitute a breach or default) under any agreement,
instrument, mortgage, deed of trust or other arrangement to which the Company is
a party or by which it or any of its assets is subject or bound, and (d) does
not require the approval, consent or waiver of or by any third party which
approval, consent or waiver has not been obtained as of the date hereof.

         3. NO FURTHER AMENDMENT. Except as amended hereby, the Agreement shall
remain in full force and effect as originally written.

         IN WITNESS WHEREOF, the parties have caused this Amendment No. 1 to
Registration Rights Agreement to be executed by their duly authorized
representatives as an agreement under seal as of the date first above written.


SILICON VALLEY BANCSHARES           SATCON TECHNOLOGY CORPORATION



By: /s/ James C. Maynard            By:  /s/ Ralph M. Norwood
   ------------------------------       ------------------------------
Title:  Officer                     Title: Vice-Pres & Chief Financial
       --------------------------          Officer
                                        ---------------------------

SILICON VALLEY BANK


By:  /s/ John K. Peck
    -----------------------------

Title:  Vice President
       --------------------------