<PAGE>

                                                                  Exhibit 10.1



THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED WITH THE SECURITIES
AND EXCHANGE COMMISSION IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER
THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND, ACCORDINGLY,
MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM,
OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE
SECURITIES ACT.


MAY 25, 2001

438,750 shares                                                   Warrant No. 6

                          SATCON TECHNOLOGY CORPORATION
                             STOCK PURCHASE WARRANT

Registered Owner:  Brown Simpson Partners I, Ltd.

         This certifies that, in consideration of the cash exercise of Warrant
No. 3, to purchase an aggregate of 675,000 shares of Common Stock (as defined
below), SatCon Technology Corporation, a Delaware corporation, the ("COMPANY")
grants the following rights to the Registered Owner, or assigns, of this
Warrant:

         1. ISSUE. Upon tender (in accordance with Section 5 hereof) to the
Company, the Company, within three (3) Business Days of the date thereof, shall
issue to the Registered Owner, or assigns, up to the number of shares specified
in Section 2 hereof of fully paid and nonassessable shares of common stock,
$0.01 par value per share, of the Company (the "COMMON STOCK"), that the
Registered Owner, or assigns, is otherwise entitled to purchase.

         2. NUMBER OF SHARES. The total number of shares of Common Stock that
the Registered Owner, or assigns, of this Warrant is entitled to receive upon
exercise of this Warrant (the "WARRANT SHARES") is 438,750 shares, subject to
adjustment from time to time as to the number and kind of securities for which
this Warrant is exercisable, all as set forth in Section 6 hereof. The Company
shall at all times reserve and hold available out of its authorized and unissued
shares of Common Stock or other securities, as the case may be, sufficient
shares of Common Stock to satisfy all conversion and purchase rights represented
by outstanding convertible securities, options and warrants, including this
Warrant. The Company covenants and agrees that all shares of Common Stock or
other securities, as the case may be, that may be issued upon the exercise of
this Warrant shall, upon issuance, be duly and validly issued, fully paid and
nonassessable, free from all taxes, liens and charges with respect to the
purchase and the issuance of the shares, and shall not have any legend or
restrictions on resale, except that each certificate representing Warrant Shares
shall bear the following legend:

                  THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED
                  WITH THE SECURITIES AND EXCHANGE COMMISSION IN RELIANCE UPON
                  AN EXEMPTION FROM REGISTRATION UNDER


<PAGE>

                  THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"),
                  AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT
                  TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES
                  ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A
                  TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF
                  THE SECURITIES ACT.

         Neither this Warrant nor the Warrant Shares shall be required to
contain the legend set forth above (or any other legend) (i) at any time after
transfer pursuant to a registration statement is effective under the Securities
Act covering such security, (ii) if in the written opinion of counsel to the
Company or the Registered Owner, experienced in the area of United States
securities laws, such legend is not required under applicable requirements of
the Securities Act (including judicial interpretations and pronouncements issued
by the staff of the Commission) or (iii) if this Warrant or the Warrant Shares
are sold pursuant to Rule 144. When requested, which request will be accompanied
by the certificate representing such shares, the Company agrees that it will
provide the Registered Owner with a certificate or certificates representing
Warrants or Warrant Shares, free from such legend at such time as such legend is
no longer required hereunder. If such certificate or certificates had previously
been issued with such a legend or any other legend, the Company shall, upon
request, receive such certificate or certificates free of any legend.

         3. EXERCISE PRICE. The per share exercise price of this Warrant,
representing the price per share at which the shares of stock issuable upon
exercise of this Warrant may be purchased, is sixteen dollars and seventy cents
($16.70), subject to adjustment from time to time pursuant to the provisions of
Section 6 hereof (the "EXERCISE PRICE").

         4. EXERCISE PERIOD. This Warrant may be exercised from May 25, 2001 up
to and including May 25, 2004 (the "EXERCISE PERIOD"). If not exercised during
this period, this Warrant and all rights granted under this Warrant shall expire
and lapse.

         5.   TENDER; ISSUANCE OF CERTIFICATES.

                  a. Subject to Section 15 hereof, this Warrant may be
exercised, in whole or in part, by (i) actual delivery of (a) the Exercise Price
in cash, (b) a duly executed Warrant Exercise Form, a copy of which is attached
to this Warrant as EXHIBIT A, properly executed by the Registered Owner, or
assigns, of this Warrant, and (c) by surrender of this Warrant. The Warrant
Shares so purchased shall be deemed to be issued to the Registered Owner as of
the close of business on the date (the "EXERCISE DATE") on which the last of the
following shall have occurred: (i) this Warrant shall have been surrendered and
(ii) the completed Warrant Exercise Form shall have been delivered and payment
shall have been made for such shares as set forth above. The payment and Warrant
Exercise Form must be delivered to the registered office of the Company either
in person or as set for in Section 12 hereof.

                  b. In lieu of physical delivery of the Warrant, provided the
Company's transfer agent is participating in the Depositary Trust Company
("DTC") Fast Automated Securities Transfer ("FAST") program, upon request of the
Registered Owner and in compliance with the provisions hereof, the Company shall
use its best efforts to cause its transfer agent to


                                     2
<PAGE>

electronically transmit the Warrant Shares to the Registered Owner by
crediting the account of the Registered Owner's Prime Broker with DTC through
its Deposit Withdrawal Agent Commission system. The time period for delivery
described herein shall apply to the electronic transmittals described herein.

                  c. Certificates for the Warrant Shares so purchased,
representing the aggregate number of shares specified in the Warrant Exercise
Form, and any cash payments due under Section 14 hereof shall be delivered to
the Registered Owner within a reasonable time, not exceeding three (3) Business
Days, after this Warrant shall have been so exercised. The certificates so
delivered shall be in such denominations as may be requested by the Registered
Owner and shall be registered in the name of the Registered Owner or such other
name as shall be designated by such Registered Owner. If this Warrant shall have
been exercised only in part, then, unless this Warrant has expired, the Company
shall, at its expense, at the time of delivery of such certificates, deliver to
the Registered Owner a new Warrant representing the number of shares with
respect to which this Warrant shall not then have been exercised.

         6.   ADJUSTMENT OF EXERCISE PRICE.

                  a. COMMON STOCK DIVIDENDS; COMMON STOCK SPLITS; REVERSE COMMON
STOCK SPLITS. If the Company, at any time while this Warrant is outstanding, (a)
shall pay a dividend on its Common Stock in securities of the Company, (b)
subdivide outstanding shares of Common Stock into a larger number of shares, (c)
combine outstanding shares of Common Stock into a smaller number of shares or
(d) issue by reclassification of shares of Common Stock any shares of capital
stock of the Company, then (i) the Exercise Price shall be multiplied by a
fraction the numerator of which shall be the number of shares of Common Stock
(excluding treasury shares, if any) outstanding before such event and the
denominator of which shall be the number of shares of Common Stock outstanding
(excluding treasury shares, if any) after such event and (ii) the number of
Warrant Shares shall be multiplied by a fraction, the numerator of which shall
be the number of shares of Common Stock (excluding treasury shares, if any)
outstanding after such event and the denominator of which shall be the number of
shares of Common Stock (excluding treasury shares, if any) outstanding before
such event. Any adjustment made pursuant to this Section 6(a) shall become
effective immediately after the record date for the determination of
shareholders entitled to receive such dividend or distribution and shall become
effective immediately after the effective date in the case of a subdivision,
combination or re-classification.

                  b. SUBSCRIPTION RIGHTS. If the Company, at any time while this
Warrant is outstanding, shall fix a record date for the distribution to all of
the holders of Common Stock evidence of its indebtedness or rights, options,
warrants or other security entitling them to subscribe for or purchase, convert
to, exchange for or otherwise acquire any security of the Company (excluding
those referred to in Section 6(a) above), then in each such case the Exercise
Price at which the Warrant shall thereafter be exercisable shall be determined
by multiplying the Exercise Price in effect immediately prior to the record date
fixed for determination of shareholders entitled to receive such distribution by
a fraction, the denominator of which shall be the Per Share Market Value of
Common Stock determined as of the record date mentioned above, and the numerator
of which shall be such Per Share Market Value of the Common Stock on such record
date less the then fair market value at such record date of the portion of such
securities or evidence of indebtedness so distributed applicable to one
outstanding share of


                                     3
<PAGE>

Common Stock as determined by the Board of Directors in good faith; PROVIDED,
HOWEVER, that in the event of a distribution exceeding in value ten percent
(10%) of the net assets of the Company, such fair market value shall be
determined in accordance with the Appraisal Procedure. Such adjustment shall
be made whenever any such distribution is made and shall become effective
immediately after the record date mentioned above.

                  c. ROUNDING. All calculations under this Section 6 shall be
made to the nearest cent or the nearest l/l00th of a share, as the case may be.

                  d. NOTICE OF ADJUSTMENT. Whenever the Exercise Price is
adjusted pursuant to Section 6(a) or (b), the Company shall promptly deliver to
the Registered Owner a notice setting forth the Exercise Price after such
adjustment and setting forth a brief statement of the facts requiring such
adjustment.

                  e. CHANGE OF CONTROL. After the occurrence of a Change of
Control, the Registered Owner shall have the right upon the exercise of this
Warrant to receive only such shares of stock and other securities, cash and
property as such Registered Owner would have received, if immediately prior to
such Change of Control, the Registered Owner had held the number of shares of
Common Stock subject to this Warrant.

                  f.  NOTICE OF CERTAIN EVENTS.  If:

                           (i) the Company shall declare a dividend (or any
                  other distribution) on its Common Stock; or

                           (ii) the Company shall declare a special nonrecurring
                  cash dividend on or a redemption of its Common Stock; or

                           (iii) the Company shall authorize the granting to the
                  holders of the Common Stock rights or warrants to subscribe
                  for or purchase any shares of capital stock of any class or of
                  any rights; or

                           (iv) the approval of any shareholders of the Company
                  shall be required in connection with any reclassification of
                  the Common Stock of the Company, any consolidation or merger
                  to which the Company is a party, any sale or transfer of all
                  or substantially all of the assets of the Company, or any
                  compulsory share exchange whereby the Common Stock is
                  converted into other securities, cash or property; or

                           (v) the Company shall authorize the voluntary or
                  involuntary dissolution, liquidation or winding up of the
                  affairs of the Company;

then the Company shall cause to be filed at each office or agency maintained for
the purpose of exercise of this Warrant, and shall cause to be delivered to the
Registered Owner, at least 10 days prior to the applicable record or effective
date hereinafter specified, a notice (provided such notice shall not include any
material non-public information) stating (x) the date on which a record is to be
taken for the purpose of such dividend, distribution, redemption, rights or
warrants, or if a record is not to be taken, the date as of which the holders of
Common Stock of


                                     4
<PAGE>

record to be entitled to such dividend, distributions, redemption, rights or
warrants are to be determined or (y) the date on which such reclassification,
consolidation, merger, sale, transfer or share exchange is expected to become
effective or close, and the date as of which it is expected that holders of
Common Stock of record shall be entitled to exchange their shares of Common
Stock for securities, cash or other property deliverable upon such
reclassification, consolidation, merger, sale, transfer or share exchange;
provided, however, that the failure to mail such notice or any defect therein
or in the mailing thereof shall not affect the validity of the corporate
action required to be specified in such notice.

                  g. ADJUSTMENT OF NUMBER OF SHARES. Upon each adjustment of the
Exercise Price as a result of the calculations made in this Section 6, this
Warrant shall thereafter evidence the right to receive, at the adjusted Exercise
Price, that number of shares of Common Stock (calculated to the nearest
one-hundredth) obtained by dividing (i) the product of the aggregate number of
shares covered by this Warrant immediately prior to such adjustment and the
Exercise Price in effect immediately prior to such adjustment of the Exercise
Price by (ii) the Exercise Price in effect immediately after such adjustment of
the Exercise Price.

         7. RESTRICTION ON CONVERSION BY EITHER THE REGISTERED OWNER OR THE
COMPANY. Notwithstanding anything herein to the contrary, in no event shall any
Registered Owner have the right or be required to exercise this Warrant if as a
result of such conversion the aggregate number of shares of Common Stock
beneficially owned by such Registered Owner and its Affiliates would exceed
4.99% of the outstanding shares of the Common Stock following such exercise. For
purposes of this Section 7, beneficial ownership shall be calculated in
accordance with Section 13(d) of the Securities Exchange Act of 1934, as
amended. The provisions of this Section 7 may be waived by a Registered Owner as
to itself (and solely as to itself) upon not less than 65 days prior written
notice to the Company, and the provisions of this Section 7 shall continue to
apply until such 65th day (or later, if stated in the notice of waiver).

         8. OFFICER'S CERTIFICATE. Whenever the number of shares purchasable
upon exercise shall be adjusted as required by the provisions of Section 6, the
Company shall forthwith file in the custody of its secretary or an assistant
secretary at its principal office and with its stock transfer agent, if any, an
officer's certificate showing the adjusted Exercise Price, number of shares or
other securities determined as herein provided, setting forth in reasonable
detail the facts requiring such adjustment and the manner of computing such
adjustment. Each such officer's certificate shall be signed by the chairman,
president or chief financial officer of the Company and by the secretary or any
assistant secretary of the Company. Each such officer's certificate shall be
made available at all reasonable times for inspection by any Registered Owner of
the Warrants and the Company shall, forthwith after each such adjustment,
deliver a copy of such certificate to the each of the Registered Owners.

         9. DEFINITIONS. As used in this Warrant, the following terms have the
following meanings:

         "AFFILIATE" means, with respect to any Person, any other Person that
directly or indirectly controls or is controlled by or under common control with
such Person. For the purposes of this definition, "CONTROL," when used with
respect to any Person, means the possession, direct or indirect, of the power to
direct or cause the direction of the management and policies of such


                                     5
<PAGE>

Person, whether through the ownership of voting securities, by contract or
otherwise; and the terms of "AFFILIATED," "CONTROLLING" and "CONTROLLED" have
meanings correlative to the foregoing.

         "APPRAISAL PROCEDURE" shall have the following meaning. The independent
directors of the Company shall determine the fair market value. The holders
shall have ten (10) Business Days to provide the Company with written notice of
its approval or disapproval of such determination. If the holders do not respond
within such ten (10) Business Day period, they will be deemed to have approved
the fair market value determination of the independent directors. If the holders
appropriately respond that they do not approve of the determination and the
independent directors and holders collectively can not agree on an appropriate
fair market value within 30 Business Days, then the Company, on the one hand,
and the holders, on the other hand shall each appoint an Appraiser. A neutral
Appraiser shall be appointed by the two party-appointed Appraisers. The three
Appraisers shall collectively ascertain the fair market value, which valuation
shall be binding upon all parties absent manifest error.

         "APPRAISER" shall mean a nationally recognized or major regional
investment banking firm or firm of independent certified public accountants of
recognized standing.

          "BUSINESS DAY" means any day except Saturday, Sunday and any day which
shall be a legal holiday or a day on which banking institutions in the state of
New York generally are authorized or required by law or other government actions
to close.

         "CHANGE OF CONTROL" means the occurrence of any of (i) an acquisition
after the date hereof by an individual or legal entity or "group" (as described
in Rule 13d-5(b)(1) promulgated under the Exchange Act) in excess of 40% of the
voting securities of the Company, (ii) a replacement of more than one-half of
the members of the Company's Board of Directors which is not approved by those
individuals who are members of the Board of Directors on the date hereof in one
or a series of related transactions, or (iii) the merger of the Company with or
into another entity, consolidation or sale of all or substantially all of the
assets of the Company in one or a series of related transactions.

          "COMMON STOCK" has the meaning assigned to it in Section 1 hereof.

         "COMPANY" means SatCon Technology Corporation, a Delaware corporation.

         "EXERCISE PERIOD" has the meaning assigned to it in Section 4 hereof.

         "EXERCISE PRICE" has the meaning assigned to it in Section 3 hereof.

         "PER SHARE MARKET VALUE" means on any particular date (i) the closing
bid price per share of the Common Stock on such date on the National Market
System of the Nasdaq Stock Market or other registered national stock exchange on
which the Common Stock is then listed or if there is no such price on such date,
then the closing bid price on such exchange or quotation system on the date
nearest preceding such date, or (ii) if the Common Stock is not listed then on
the National Market System of the Nasdaq Stock Market or any registered national
stock exchange, the closing bid price for a share of Common Stock in the
over-the-counter market, as reported by the National Quotation Bureau
Incorporated (or similar organization or agency succeeding to its functions of
reporting prices) at the close of business on such date, or (iii) if the Common
Stock


                                     6
<PAGE>


is not then publicly traded the fair market value of a share of Common Stock
as determined in accordance with the Appraisal Procedure. In addition, all
determinations of the Per Share Market Value shall be appropriately adjusted
for any stock dividends, stock splits or other similar transactions during
such period.

         "PERSON" means a corporation, an association, a partnership, an
organization, a business, an individual, a government or political subdivision
thereof or a governmental agency.

         "REGISTERED OWNER" means the person identified on the face of this
Warrant as the registered owner hereof or such other person as shown on the
records of the Company as being the registered owner of this Warrant or their
assigns.

         "REGISTRATION RIGHTS AGREEMENT" means that certain Registration Rights
Agreement, dated as of August 25, 1999, among the Company and affiliates of the
Registered Owner.

          "WARRANT(S)" means this warrant.

         10. REGISTRATION RIGHTS. This Warrant shall be deemed a "New Warrant"
under the Registration Rights Agreement and Amendment No. 1 thereto.

         11. RESERVATION OF UNDERLYING SHARES; LISTING. The Company covenants
that it will at all times reserve and keep available out of its authorized
shares of Common Stock, free from preemptive rights, solely for the purpose of
issue upon exercise of the Warrants as herein provided, such number of shares of
the Common Stock as shall then be issuable upon the exercise of all outstanding
Warrants into Common Stock. The Company covenants that all shares of the Common
Stock issued upon exercise of the Warrant which shall be so issuable shall, when
issued, be duly and validly issued and fully paid and non-assessable. The
Company shall promptly secure the listing of the shares of Common Stock issuable
upon exercise of the Warrant upon each national securities exchange or automated
quotation system, if any, upon which shares of Common Stock are then listed
(subject to official notice of issuance upon exercise of this Warrant) and shall
maintain, so long as any other shares of Common Stock shall be so listed, such
listing of all shares of Common Stock form time to time issuable upon the
exercise of this Warrant; and the Company shall so list on each national
securities exchange or automated quotation system, as the case may be, and shall
maintain such listing of, any other shares of capital stock of the Company
issuable upon the exercise of this Warrant if and so long as any shares of the
same class shall be listed on such national securities exchange or automated
quotation system.

         12. NOTICES. Any notice or other communication required or permitted to
be given hereunder shall be in writing and shall be deemed to have been received
(a) upon hand delivery (receipt acknowledged) or delivery by telex (with correct
answer back received), telecopy or facsimile (with transmission confirmation
report) at the address or number designated below (if received by 5:00 p.m.
eastern time where such notice is to be received), or the first Business Day
following such delivery (if received after 5:00 p.m. eastern time where such
notice is to be received) or (b) on the second Business Day following the date
of mailing by express courier service, fully prepaid, addressed to such address,
or upon actual receipt of such mailing, whichever shall first occur. The
addresses for such communications are (i) if to the Company to


                                     7
<PAGE>

SatCon Technology Corporation, 161 First Street, Cambridge, MA 02142-1221,
Attn: President and Chief Executive Officer, fax no. (617) 576-7455, with
copies to Hale and Dorr LLP, 60 State Street, Boston, MA 02109, Attn: Jeffrey
N. Carp, Esq., fax no. (617) 526-5000 and (ii) if to the Registered Owner to
Brown Simpson Partners I, Ltd., 152 West 57th Street, 21st Floor, New York,
New York 10019, Attn: Peter Greene, fax no. (212) 817-5391 with copies to
Akin, Gump, Strauss, Hauer & Feld, L.L.P., 590 Madison Avenue, New York, New
York 10022, Attn: James Kaye, Esq., fax no. (212) 872-1002 or such other
address as may be designated in writing hereafter, in the same manner, by
such Person.

         13. COMPLIANCE WITH GOVERNMENTAL REQUIREMENTS. The Company covenants
that if any shares of Common Stock required to be reserved for purposes of
exercise of Warrants hereunder require registration with or approval of any
governmental authority under any Federal or state law, or any national
securities exchange, before such shares may be issued upon exercise, the Company
will use its best efforts to cause such shares to be duly registered or
approved, as the case may be.

         14. FRACTIONAL SHARES. Upon any exercise hereunder, the Company shall
not be required to issue stock certificates representing fractions of shares of
the Common Stock, but may if otherwise permitted make a cash payment in respect
of any final fraction of a share based on the Per Share Market Value at such
time. If the Company elects not, or is unable, to make such a cash payment, the
Registered Owner shall be entitled to receive, in lieu of the final fraction of
a share, one whole share of Common Stock.

         15. PAYMENT OF TAX UPON ISSUE OF TRANSFER. The issuance of certificates
for shares of the Common Stock upon exercise of the Warrants shall be made
without charge to the Registered Owners thereof for any documentary stamp or
similar taxes that may be payable in respect of the issue or delivery of such
certificate, provided that the Company shall not be required to pay any tax that
may be payable in respect of any transfer involved in the issuance and delivery
of any such certificate upon exercise in a name other than that of the
Registered Owner of such Warrant so converted and the Company shall not be
required to issue or deliver such certificates unless or until the person or
persons requesting the issuance thereof shall have paid to the Company the
amount of such tax or shall have established to the satisfaction of the Company
that such tax has been paid.

         16. WARRANTS OWNED BY COMPANY DEEMED NOT OUTSTANDING. In determining
whether the holders of the outstanding Warrants have concurred in any direction,
consent or waiver under this Warrant, warrants which are owned by the Company or
by any person directly or indirectly controlling or controlled by or under
direct or indirect common control with the Company shall be disregarded and
deemed not to be outstanding for the purpose of any such determination. Warrants
so owned which have been pledged in good faith may be regarded as outstanding if
the pledgee establishes to the satisfaction of the Company the pledgee's right
so to act with respect to such warrants and that the pledgee is not the Company
or any other obligor upon the securities or any Affiliate of the Company or any
other obligor on the warrants.

         17. EFFECT OF HEADINGS. The section headings herein are for convenience
only and shall not affect the construction hereof.


                                     8
<PAGE>

         18. NO RIGHTS AS STOCKHOLDER. This Warrant shall not entitle the
Registered Owner to any rights as a stockholder of the Company, including
without limitation, the right to vote, to receive dividends and other
distributions, or to receive notice of, or to attend, meetings of stockholders
or any other proceedings of the Company, unless and to the extent converted into
shares of Common Stock in accordance with the terms hereof.

         19. CERTAIN ACTIONS PROHIBITED. The Company will not, by amendment of
its charter or through any 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 by it hereunder, but will at all times in good faith
assist in the carrying out of all the provisions of this Warrant and in the
taking of all such action as may reasonably be requested by the holder of this
Warrant in order to protect the exercise privilege of the holder of this Warrant
against dilution or other impairment, consistent with the tenor and purpose of
this Warrant. Without limiting the generality of the foregoing, the Company (i)
will not increase the par value of any shares of Common Stock receivable upon
the exercise of this Warrant above the Exercise Price then in effect, and (ii)
will take all such actions as may be necessary or appropriate in order that the
Company may validly and legally issue fully paid and nonassessable shares of
Common Stock upon the exercise of this Warrant.

         20. SHAREHOLDER RIGHTS PLAN. Notwithstanding the foregoing, in the
event that the Company shall distribute "poison pill" rights pursuant to a
"poison pill" shareholder rights plan (the "RIGHTS"), the Company shall, in lieu
of making any adjustment pursuant to Section 6 hereof, make proper provision so
that each Registered Owner who exercises a Warrant after the record date for
such distribution and prior to the expiration or redemption of the Rights shall
be entitled to receive upon such exercise, in addition to the shares of Common
Stock issuable upon such exercise, a number of Rights to be determined as
follows: (i) if such exercise occurs on or prior to the date for the
distribution to the holders of Rights of separate certificates evidencing such
Rights (the "DISTRIBUTION DATE"), the same number of Rights to which a holder of
a number of shares of Common Stock equal to the number of shares of Common Stock
issuable upon such exercise at the time of such exercise would be entitled in
accordance with the terms and provisions of and applicable to the Rights; and
(ii) if such exercise occurs after the Distribution Date, the same number of
Rights to which a holder of the number of shares into which the Warrant to
exercised was exercisable immediately prior to the Distribution Date would have
been entitled on the Distribution Date in accordance with the terms and
provisions of and applicable to the Rights, and in each case subject to the
terms and conditions of the Rights.

         21. SUCCESSORS AND ASSIGNS. This Warrant shall be binding upon and
inure to the benefit of the Registered Owners and its assigns, and shall be
binding upon any entity succeeding to the Company by merger or acquisition of
all or substantially all the assets of the Company. The Company may not assign
this Warrant or any rights or obligations hereunder without the prior written
consent of the Registered Owner. The Registered Owner may assign this Warrant
without the prior written consent of the Company.

         22. TRANSFERS. The Company shall maintain a register (the "REGISTER")
containing the name and address of the Registered Owner of this Warrant, which
Register can be relied upon by the Company as conclusive evidence of the
Registered Owner. If the Registered Owner transfers or assigns this Warrant it
shall promptly notify the Company in writing of the name and address


                                     9
<PAGE>

of the person to which such transfer or assignation was made. Upon receipt of
such notice the Company shall immediately update the Register to incorporate
the new Registered Owner.

         23. GOVERNING LAW. This Warrant shall be governed by and construed and
enforced in accordance with the internal laws of the State of New York without
regard to the principles of conflicts of law thereof. Each party hereby
irrevocably submits to the nonexclusive jurisdiction of the state and federal
courts sitting in the City of New York, Borough of Manhattan, for the
adjudication of any dispute hereunder or in connection herewith or with any
transaction contemplated hereby or discussed herein, and hereby irrevocably
waives, and agrees not to assert in any suit, action or proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, that
such suit, action or proceeding is improper. Each party hereby irrevocably
waives personal service of process and consents to process being served in any
such suit, action or proceeding by mailing a copy thereof to such party at the
address for such notices to it under this Warrant and agrees that such service
shall constitute good and sufficient service of process and notice thereof.
Nothing contained herein shall be deemed to limit in any way any right to serve
process in any manner permitted by law. EACH PARTY HEREBY IRREVOCABLY WAIVES ANY
RIGHT IT MAY HAVE, AND AGREES NOT TO REQUEST, A JURY TRIAL FOR THE ADJUDICATION
OF ANY DISPUTE HEREUNDER OR IN CONNECTION HEREWITH OR ARISING OUT OF THIS
AGREEMENT OR ANY TRANSACTION CONTEMPLATED HEREBY.


                                     10

<PAGE>



         IN WITNESS WHEREOF, the Company has caused this Warrant to be executed
by its duly authorized officer as of the date first set forth above.

                                       SATCON TECHNOLOGY CORPORATION



                                       By: /s/ Sean F. Moran
                                          -----------------------------------
                                       Name: Sean F. Moran
                                            ---------------------------------
                                       Title: Chief Financial Officer
                                             --------------------------------


                                     11

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                                    EXHIBIT A

                              WARRANT EXERCISE FORM


TO:      SatCon Technology Corporation

         The undersigned hereby: (1) irrevocably subscribes for and offers to
purchase _______ shares of Common Stock of SatCon Technology Corporation,
pursuant to Warrant No. 6 heretofore issued to Brown Simpson Partners I, Ltd. On
May 25, 2001; (2) encloses either (a) a cash payment of $__________ or (b) a
Warrant representing _____ shares of Common Stock valued at the Per Share Market
Price of $ _____ on __________, _____, for these shares at a price of $____ per
share (as adjusted pursuant to the provisions of the Warrant); and (3) requests
that a certificate for the shares be issued in the name of the undersigned and
delivered to the undersigned at the address specified below.

                           Date:
                                                       -----------------------
                           Investor Name:
                                                       -----------------------
                           Taxpayer Identification
                                                       -----------------------
                           Number:
                                                       -----------------------
                           By:
                                                       -----------------------
                           Printed Name:
                                                       -----------------------
                           Title:
                                                       -----------------------
                           Address:
                                                       -----------------------

                  Note: The above signature should correspond exactly with the
                  name on the face of the Warrant or with the name of assignee
                  appearing in assignment form below.

AND, if said number of shares shall not be all the shares purchasable under the
Warrant, a new warrant certificate is to be issued in the name of said
undersigned for the balance remaining of the shares purchasable thereunder less
any fraction of a share paid in cash and delivered to the address stated above.


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