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                                                                   EXHIBIT 10.42

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: 181,951, subject to adjustment
Class of Stock: Common Stock, $0.01 par value per share
Exercise Price: $1.374, subject to adjustment
Issue Date:  September 13, 2002
Expiration Date:  September 12, 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 One Hundred
Eighty-one Thousand Nine Hundred Fifty-one (181,951) 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 $1.374 (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 Company. Unless Holder is

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

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                     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 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

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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.

             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

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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.

                     (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

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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 of even
date herewith. The Company represents and warrants to Holder that the Company's
execution, delivery and performance of such 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.

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.

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             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.

             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

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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 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.

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             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.

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     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/Joseph S. Moran                       By:/s/David B. Eisenhaure
   ----------------------------------         -------------------------
Name:Joseph S. Moran                        Name:David B. Eisenhaure
Title:Vice President, General Counsel       Title:President and Chief Executive
         & Secretary                              Officer

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                                   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)

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                          REGISTRATION RIGHTS AGREEMENT

        THIS REGISTRATION RIGHTS AGREEMENT is entered into as of September 13,
2002, by and between Silicon Valley Bank ("Purchaser") and SatCon Technology
Corporation, a Delaware corporation (the "Company").

                                    RECITALS

        A.   Concurrently with the execution of this Agreement, Purchaser is
acquiring from the Company a Warrant to Purchase Stock (the "Warrant") pursuant
to which Purchaser has rights to acquire from the Company the Shares (as defined
in the Warrant).

        B.   By this Agreement, Purchaser and the Company desire to set forth
the registration rights of the Shares all as provided herein.

             NOW, THEREFORE, in consideration of the premises and the mutual
promises, covenants and conditions hereinafter set forth, the parties hereto
mutually agree as follows:

        1.   REGISTRATION RIGHTS. The Company covenants and agrees as follows:

             1.1     DEFINITIONS.  For purposes of this Section 1:

                     (a)    The term "register," "registered," and
"registration" refer to a registration effected by preparing and filing a
registration statement or similar document in compliance with the Securities Act
of 1933, as amended, and the rules and regulations thereunder (the "Securities
Act"), and the declaration or ordering of effectiveness of such registration
statement or document;

                     (b)    The term "Registrable Securities" means (i) the
Shares issued and issuable upon exercise or conversion of the Warrant, and (ii)
any Common Stock (as defined in the Warrant) or other securities of the Company
issued as (or issuable upon the conversion or exercise of any warrant, right or
other security which is issued as) a dividend or other distribution with respect
to, or in exchange for or in replacement of, the Shares.

                     (c)    The terms "Holder" or "Holders" means Purchaser
and its qualifying transferees under subsection 1.8 hereof who hold Registrable
Securities.

                     (d)    The term "SEC" means the Securities and Exchange
Commission.

                     (e)    The terms "Form S-1," "Form S-3" etc. shall mean
those forms with such designations as are required by the SEC and any successor
or replacement forms adopted by the SEC.

             1.2     COMPANY REGISTRATION.

                     (a)    REGISTRATION. If at any time or from time to time,
the Company shall determine to register any of its securities, for its own
account or the account of any of its shareholders, other than a registration on
Form S-8 relating solely to employee stock option or purchase plans or on Form
S-4 relating solely to an SEC Rule 145 transaction, the Company will:

                            (i)   promptly give to each Holder written notice
thereof (which shall include a list of the jurisdictions in which the Company
intends to attempt to qualify such securities under the applicable blue sky or
other state securities laws); and

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                           (ii)   include in such registration (and
qualifications), and in any underwriting involved therein, all the Registrable
Securities specified in a written request or requests, made within 30 days after
receipt of such written notice from the Company, by any Holder or Holders,
except as set forth in subsection 1.2(c) below.

                     (b)    UNDERWRITING. If the registration of which the
Company gives notice is for a registered public offering involving a
firm-commitment underwriting, the Company shall so advise the Holders as a part
of the written notice given pursuant to subsection 1.2(a)(i). In such event the
right of any Holder to registration pursuant to this subsection 1.2 shall be
conditioned upon such Holder's participation in such underwriting and the
inclusion of such Holder's Registrable Securities in the underwriting to the
extent provided herein. All Holders proposing to distribute their securities
through such underwriting shall (together with the Company and the other
shareholders distributing their securities through such underwriting) enter into
an underwriting agreement in customary form (and not inconsistent with the terms
hereof) with the underwriter or underwriters selected for such underwriting by
the Company.

                     (c)    In the case of any registration of Common Stock by
the Company in a firm-commitment underwriting, if the managing underwriters
give written advice to the Company that marketing factors require a limitation
on the number of shares of Common Stock (or other securities convertible into or
exercisable or exchangeable for Common Stock) to be offered and sold by
stockholders of Company in such offering, there shall be included in the
offering: (i) first, all securities proposed by Company to be sold for its
account; and (ii) second, that number of shares of Common Stock, if any,
requested to be included in such registration statement by Holders and by other
stockholders of the Company having contractual rights to include shares in such
registration, on a pro rata basis based upon the number of shares of Common
Stock each Holder and each such other stockholder beneficially owns.

             1.3     EXPENSES OF REGISTRATION. All expenses incurred in
connection with any registration, qualification or compliance pursuant to this
Section 1 including without limitation, all registration, filing and
qualification fees, printing expenses, underwriting fees, discounts and
commissions (other than underwriting fees, discounts and commissions in respect
of Registrable Securities included in such registration), fees and disbursements
of counsel for the Company and expenses of any special audits incidental to or
required by such registration, shall be borne by the Company. All expenses of
any registered offering not otherwise borne by the Company will be borne pro
rata among the Holders, any other shareholders of the Company participating in
such offering and the Company.

             1.4     REGISTRATION PROCEDURES. In the case of each registration,
qualification or compliance effected by the Company pursuant to this
Registration Rights Agreement, the Company will keep each Holder participating
therein advised in writing as to the initiation of each registration,
qualification and compliance and as to the completion thereof. At its expense
the Company will:

                     (a)    Prepare and file with the SEC a registration
statement with respect to such Registrable Securities and use its best efforts
to cause such registration statement to become effective, and, upon the request
of the Holders of a majority of the Registrable Securities registered
thereunder, keep such registration statement effective for up to 120 days (the
"Effective Period").

                     (b)    Prepare and file with the SEC such amendments and
supplements to such registration statement and the prospectus used in connection
with such registration statement as may be necessary to comply with the
provisions of the Securities Act with respect to the disposition of all
securities covered by such registration statement.

                     (c)    Furnish to the Holders such numbers of copies of
a prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other

<Page>

documents as they may reasonably request in order to facilitate the disposition
of Registrable Securities owned by them.

                     (d)    Use its best efforts to register and qualify the
securities covered by such registration statement under such other securities or
Blue Sky laws of such jurisdictions as shall be reasonably requested by the
Holders, provided that the Company shall not be required in connection therewith
or as a condition thereto to qualify to do business or to file a general consent
to service of process in any such states or jurisdictions.

                     (e)    In the event of any underwritten public offering,
enter into and perform its obligations under an underwriting agreement, in usual
and customary form, with the managing underwriter of such offering. Each Holder
participating in such underwriting shall also enter into and perform its
obligations under such an agreement provided that all other shareholders of the
Company participating in such offering do the same.

                     (f)    Notify each Holder of Registrable Securities
covered by such registration statement at any time when a prospectus relating
thereto is required to be delivered under the Securities Act or the happening of
any event as a result of which the prospectus included in such registration
statement, as then in effect, includes an untrue statement of a material fact or
omits to state a material fact required to be stated therein or necessary to
make the statements therein not misleading in the light of the circumstances
then existing.

             1.5     INDEMNIFICATION.

                     (a)    The Company will indemnify each Holder of
Registrable Securities and each of its officers, directors and partners, and
each person controlling such Holder within the meaning of Section 15 of the
Securities Act ("controlling person"), and each underwriter, if any, and each
controlling person of such underwriter, with respect to which registration,
qualification or compliance of Registrable Securities has been effected pursuant
to this Registration Rights Agreement, against all claims, losses, expenses,
damages and liabilities (or actions in respect thereto) arising out of or based
on any untrue statement (or alleged untrue statement) of a material fact
contained in any prospectus, offering circular or other document (including any
related registration statement, notification or the like) incident to any such
registration, qualification or compliance, or based on any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statement therein not misleading, or any violation or
alleged violation by the Company of the Securities Act, the Securities Exchange
Act of 1934, as amended, and the rules and regulations thereunder ("Exchange
Act") or any state securities law applicable to the Company or any rule or
regulation promulgated any such state law and relating to action or inaction
required of the Company in connection with any such registration, qualification
or compliance, and will reimburse each such Holder, each of its officers,
directors and partners, and each person controlling such Holder, each such
underwriter and each person who controls any such underwriter, within a
reasonable amount of time after incurred for any reasonable legal and any other
expenses incurred in connection with investigating, defending or settling any
such claim, loss, damage, liability or action; PROVIDED, HOWEVER, that the
indemnity agreement contained in this subsection 1.5(a) shall not apply to
amounts paid in settlement of any such claim, loss, damage, liability, or action
if such settlement is effected without the consent of the Company (which consent
shall not be unreasonably withheld or delayed); AND PROVIDED FURTHER, that the
Company will not be liable in any such case to the extent that any such claim,
loss, damage or liability arises out of or is based on any untrue statement or
omission made in reliance upon and conformity with written information furnished
to the Company specifically for use therein by an instrument duly executed by
such Holder.

                     (b)    Each Holder will, if Registrable Securities held
by or issuable to such Holder are included in the securities as to which such
registration, qualification or compliance is being effected, indemnify the
Company, each of its directors, officers and controlling persons, each
underwriter, if any, of

<Page>

the Company's securities covered by such a registration statement, and each
controlling person of such underwriter, and each other Holder, each of its
officers, directors, partners and controlling persons, against all claims,
losses, expenses, damages and liabilities (or actions in respect thereof)
arising out of or based on any untrue statement (or alleged untrue statement) of
a material fact contained in any such registration statement, prospectus,
offering circular or other document, or any omission (or alleged omission) to
state therein a material fact required to be stated therein or necessary to make
the statements therein not misleading, and will reimburse the Company, such
Holders, such directors, officers, partners, persons or underwriters for any
reasonable legal or any other expenses incurred in connection with
investigating, defending or settling any such claim, loss, damage, liability or
action, in each case to the extent, but only to the extent, that such untrue
statement (or alleged untrue statement) or omission (or alleged omission) is
made in such registration statement, prospectus, offering circular or other
document in reliance upon and in conformity with written information furnished
to the Company specifically for use therein by an instrument duly executed by
such Holder; PROVIDED, HOWEVER, that the indemnity agreement contained in this
subsection 1.5(b) shall not apply to amounts paid in settlement of any such
claim, loss, damage, liability or action if such settlement is effected without
the consent of the Holder, (which consent shall not be unreasonably withheld or
delayed); AND PROVIDED FURTHER, that the total amount for which any Holder shall
be liable under this subsection 1.5(b) shall not in any event exceed the
aggregate net proceeds received by such Holder from the sale of Registrable
Securities held by such Holder in such registration.

                     (c)    Each party entitled to indemnification under this
subsection 1.5 (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 the Indemnified Party may participate in such
defense at such party's expense; 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 hereunder, unless such failure resulted in
prejudice to the Indemnifying Party; and provided further, that an Indemnified
Party (together with all other Indemnified Parties which may be represented
without conflict by one counsel) shall have the right to retain one separate
counsel, with the fees and expenses to be paid by the Indemnifying Party, 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 such 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 to such
claim or litigation.

                     (d)    In order to provide for just and equitable
contribution in circumstances in which the indemnification provided for in this
Section 1.5 is due in accordance with its terms but for any reason is judicially
determined to be unenforceable against the Indemnifying Party or otherwise
unavailable to the Indemnified Party in respect to any losses, claims, damages
and liabilities referred to herein, then the Indemnifying Party shall, in lieu
of indemnifying such Indemnified Party, contribute to the amount paid or payable
by such Indemnified party as a result of such losses, claims, damages or
liabilities to which such party may be subject in such proportion as is
appropriate to reflect the relative fault of the Company, on the one hand, and
the selling Holders, on the other hand, in connection with the statements or
omissions which resulted in such losses, claims, damages or liabilities, as well
as any other relevant equitable considerations. The relative fault of the
Company and such selling Holders shall be determined by reference to, among
other things, whether the untrue or alleged untrue statement, or omission or
alleged omission, of material fact related to the information supplied by the
Company or such selling Holders and the parties' relative intent, knowledge,
access to information and opportunity to correct or prevent such statement or
omission. The Company and Holders agree that it would not be just and equitable
if contribution pursuant to this Section 1.5(d)

<Page>

were determined by pro rata allocation or any other method of allocation which
does not take account of the equitable considerations referred to above.
Notwithstanding the provisions of this Section 1.5(d), (i) in no case shall any
Holder be liable or responsible for any amount in excess of the net proceeds
received by such Holder from the sale of Registrable Securities pursuant to such
registration; and (ii) no person adjudged guilty of fraudulent misrepresentation
(within the meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any person who was not adjudged guilty of such fraudulent
misrepresentation. Any party entitled to contribution shall, promptly after
receipt of notice of commencement of any action, suit or proceeding against such
party in respect of which a claim for contribution may be made against another
party or parties under this Section 1.5(d), notify such party or parties from
whom contribution may be sought, but the omission so to notify such party or
parties from whom contribution may be sought shall not, in the absence of actual
prejudice to such party or parties, relieve it or them from such contribution
obligation. No party shall be liable for contribution with respect to any
action, suit, proceeding or claim settled without its written consent.

             1.6     INFORMATION BY HOLDER. Any Holder or Holders of Registrable
Securities included in any registration shall promptly furnish to the Company
such information regarding such Holder or Holders and the distribution proposed
by such Holder or Holders as the Company may request in writing and as shall be
required in connection with any registration, qualification or compliance
referred to herein.

             1.7     RULE 144 REPORTING. With a view to making available to
Holders the benefits of certain rules and regulations of the SEC which may
permit the sale of the Registrable Securities to the public without
registration, the Company agrees at all times to:

                     (a)    make and keep public information available, as those
terms are understood and defined in SEC Rule 144;

                     (b)    file with the SEC in a timely manner all reports and
other documents required of the Company under the Securities Act and the
Exchange Act; and

                     (c)    so long as a Holder owns any Registrable Securities,
to furnish to such Holder forthwith upon request a written statement by the
Company as to its compliance with the reporting requirements of said Rule 144,
and of the Securities Act and the Exchange Act, a copy of the most recent annual
or quarterly report of the Company, and such other reports and documents so
filed by the Company as the Holder may reasonably request in complying with any
rule or regulation of the SEC allowing the Holder to sell any such securities
without registration.

             1.8     TRANSFER OF REGISTRATION RIGHTS. Each Holder's rights
hereunder may be assigned to a transferee or assignee of such Holder's
Registrable Securities not sold to the public, provided, that the Company is
given written notice by such Holder at the time of or within a reasonable time
after said transfer, stating the name and address of said transferee or assignee
and identifying the securities with respect to which such registration rights
are being assigned.

        2.   GENERAL.

             2.1     WAIVERS AND AMENDMENTS. With the written consent of the
record or beneficial holders of at least a majority of the Registrable
Securities, the obligations of the Company and the rights of the Holders of the
Registrable Securities under this agreement may be waived (either generally or
in a particular instance, either retroactively or prospectively, and either for
a specified period of time or indefinitely), and with the same consent the
Company, when authorized by resolution of its Board of Directors, may enter into
a supplementary agreement for the purpose of adding any provisions to or
changing in any manner or eliminating any of the provisions of this Agreement;
provided, however, that no such modification, amendment or waiver shall reduce
the aforesaid percentage of Registrable Securities without

<Page>

the consent of all of the Holders of the Registrable Securities. Upon the
effectuation of each such waiver, consent, agreement of amendment or
modification, the Company shall promptly give written notice thereof to the
record holders of the Registrable Securities who have not previously consented
thereto in writing. This Agreement or any provision hereof may be changed,
waived, discharged or terminated only by a statement in writing signed by the
party against which enforcement of the change, waiver, discharge or termination
is sought, except to the extent provided in this subsection 2.1.

             2.2     GOVERNING LAW. This Agreement shall be governed in all
respects by the laws of the Commonwealth of Massachusetts as such laws are
applied to agreements between Massachusetts residents entered into and to be
performed entirely within Massachusetts.

             2.3     SUCCESSORS AND ASSIGNS. Except as otherwise expressly
provided herein, the provisions hereof shall inure to the benefit of, and be
binding upon, the successors, assigns, heirs, executors and administrators of
the parties hereto.

             2.4     ENTIRE AGREEMENT. Except as set forth below, this Agreement
and the other documents delivered pursuant hereto constitute the full and entire
understanding and agreement between the parties with regard to the subjects
hereof and thereof.

             2.5     NOTICES, ETC. All notices and other communications required
or permitted hereunder shall be in writing and shall be mailed by first class
mail, postage prepaid, certified or registered mail, return receipt requested,
addressed (a) if to Holder, at such Holder's address(es) as set forth below, or
at such other address(es) as such Holder shall have furnished to the Company in
writing, or (b) if to the Company, at the Company's address set forth below, or
at such other address as the Company shall have furnished to the Holder in
writing.

             2.6     SEVERABILITY. In case any provision of this Agreement shall
be invalid, illegal, or unenforceable, the validity, legality and enforceability
of the remaining provisions of this Agreement or any provision of the other
Agreement s shall not in any way be affected or impaired thereby.

             2.7     TITLES AND SUBTITLES. The titles of the sections and
subsections of this Agreement are for convenience of reference only and are not
to be considered in construing this Agreement.

             2.8     COUNTERPARTS. This Agreement may be executed in any number
of counterparts, each of which shall be an original, but all of which together
shall constitute one instrument.

                  [REMAINDER OF PAGE LEFT BLANK INTENTIONALLY]

<Page>

     IN WITNESS WHEREOF, the parties have caused this Registration Rights
Agreement to be executed by their duly authorized representatives as of the date
first above written.

PURCHASER                             COMPANY

SILICON VALLEY BANK                   SATCON TECHNOLOGY CORPORATION

By: /s/ John K. Peck                  By:  /s/David B. Eisenhaure
    -----------------------------          ----------------------

Name:  John K. Peck                   Name:  David B. Eisenhaure
      ---------------------------           ----------------------
               (print)                            (print)

Title: Vice President                 Title: President & Chief Executive Officer
      ---------------------------            -----------------------------------
Address:                              Address: 161 First Street
                                               Cambridge, MA 02142
                                               ---------------------------------

copy to: Silicon Valley Bank
                 Treasury Department
                 3003 Tasman Drive, HA 200
                 Santa Clara, CA 95054<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
       --------------------------

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