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                                                                   Exhibit 10.30

                       MTI REGISTRATION RIGHTS AGREEMENT
                       ---------------------------------


          This MTI Registration Rights Agreement (this "Agreement") is made and
                                                        ---------
entered into as of October 21, 1999, between Mechanical Technology Incorporated,
a New York corporation (the "Company"), and SatCon Technology Corporation, a
                             -------
Delaware corporation (the "Purchaser").
                           ---------

          This Agreement is made pursuant to the Securities Purchase Agreement,
dated as of the date hereof among the Company and the Purchasers (the "Purchase
                                                                       --------
Agreement").
---------

          The Company and the Purchasers hereby agree as follows:

     1.   Definitions
          -----------

          Capitalized terms used and not otherwise defined herein shall have the
meanings given such terms in the Purchase Agreement. As used in this Agreement,
the following terms shall 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 Person,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "affiliated," controlling" and "controlled" have meanings
               ----------   -----------       ----------
correlative to the foregoing.

          "Commission" means the Securities and Exchange Commission.
           ----------

          "Common Stock" means the Company's Common Stock, par value $1.00 per
           ------------
share.

          "Holder" or "Holders" means the holder or holders, as the case may be,
           ------      -------
from time to time of Registrable Securities.

          "Indemnified Party"  has the meaning set forth in Section 4(c) hereof.
           -----------------

          "Indemnifying Party" has the meaning set forth in Section 4(c) hereof.
           ------------------

          "Person" means an individual or a corporation, partnership, trust,
           ------
     incorporated or unincorporated association, joint venture, limited
     liability company, joint stock company, government (or an agency or
     political subdivision thereof) or other entity of any kind.
<PAGE>

          "Registrable Securities" means the shares of Common Stock issued or
           ----------------------
issuable upon exercise of the Warrants, and any shares of the Company's capital
stock issued as a result of any stock split, stock dividend, recapitalization,
exchange or similar event; provided, that Registrable Securities shall not
include any such shares that are eligible for sale under Rule 144(k).

          "Registration Statement" means the Initial Registration Statement and
           ----------------------
any additional registration statements contemplated by Section 3, including (in
each case) the Prospectus, amendments and supplements to such registration
statement or Prospectus, including pre- and post-effective amendments, all
exhibits thereto, and all material incorporated by reference in such
registration statement.

          "Rule 144" means Rule 144 promulgated by the Commission pursuant to
           --------
the Securities Act, as such Rule may be amended from time to time, or any
similar rule or regulation hereafter adopted by the Commission having
substantially the same effect as such Rule.

          "Rule 158" means Rule 158 promulgated by the Commission pursuant to
           --------
the Securities Act, as such Rule may be amended from time to time, or any
similar rule or regulation hereafter adopted by the Commission having
substantially the same effect as such Rule.

          "Rule 415" means Rule 415 promulgated by the Commission pursuant to
           --------
the Securities Act, as such Rule may be amended from time to time, or any
similar rule or regulation hereafter adopted by the Commission having
substantially the same effect as such Rule.

          "Securities" means the Company's Common Stock issuable pursuant to the
           ----------
Purchase Agreement.

          "Securities Act" means the Securities Act of 1933, as amended.
           --------------

          "Underlying Shares" means the shares of Common Stock issuable upon
           -----------------
exercise of the Warrants.

          "Underwritten Registration or Underwritten Offering" means a
           --------------------------------------------------
registration in connection with which securities of the Company are sold to an
underwriter for reoffering to the public pursuant to an effective registration
statement.

          "Warrants" means the warrants issuable to the Purchaser pursuant to
           --------
the Purchase Agreement.

     2.   Piggyback Registrations.  Except as provided herein if, at any time
          -----------------------
when there is not an effective Registration Statement covering the Registrable
Securities, the Company shall determine to prepare and file with the Commission
a registration statement relating to an offering for its own account or the
account of others under the Securities Act of any of its equity securities,
other than on Form S-2 (but only in connection with a rights offering), S-4 or
Form S-8 (each as promulgated under the Securities Act) or their then
equivalents relating to equity securities to be issued solely to existing
shareholders or solely in connection with any acquisition

                                       2
<PAGE>

of any entity or business or equity securities issuable in connection with stock
option or other employee benefit plans, the Company shall send to each Holder of
Registrable Securities written notice of such determination and, if within ten
(10) days after receipt of such notice, any such Holder shall so request in
writing, (which request shall specify the Registrable Securities intended to be
disposed of by the Purchasers), the Company will use reasonable efforts to
effect the registration under the Securities Act of all Registrable Securities
which the Company has been so requested to register by the Holder, to the extent
requisite to permit the disposition of the Registrable Securities so to be
registered, provided that if at any time after giving written notice of its
intention to register any securities and prior to the effective date of the
registration statement filed in connection with such registration, the Company
shall determine for any reason not to register or to delay registration of such
securities, the Company may, at its election, give written notice of such
determination to such Holder and, thereupon, (i) in the case of a determination
not to register, shall be relieved of its obligation to register any Registrable
Securities in connection with such registration (but not from its obligation to
pay expenses in accordance with this Agreement), and (ii) in the case of a
determination to delay registering, shall be permitted to delay registering any
Registrable Securities being registered pursuant to this Section 2 for the same
period as the delay in registering such other securities. The Company shall
include in such registration statement all or any part of such Registrable
Securities such Holder requests to be registered; provided, however, that the
                                                  --------  -------
Company shall not be required to register any Registrable Securities pursuant to
this Section 2 that are eligible for sale pursuant to Rule 144(k) of the
Securities Act. In the case of an underwritten public offering, if the managing
underwriter(s) or underwriter(s) should reasonably object to the inclusion of
the Registrable Securities in such registration statement, then if the Company
after consultation with the Underwriter's representative should reasonably
determine that the inclusion of such Registrable Securities would materially
adversely affect the offering contemplated in such registration statement, and
based on such determination recommends inclusion in such registration statement
of fewer Registrable Securities then proposed to be sold by the Holders, then
(x) the number of Registrable Securities of the Holder and other holders of
piggy-back registration rights included in such registration statement shall be
reduced pro rata among such Holders and other holders of piggy-back registration
rights (based upon the number of Registrable Securities requested to be included
in the registration) or, in the case of other holders of piggy-back registration
rights, in the manner provided for in that applicable agreement, or (y) none of
the Registrable Securities of the Holders shall be included in such registration
statement if the Company, after consultation with the underwriter(s), recommends
the inclusion of none of such Registrable Securities; provided, however, that if
                                                      --------  -------
securities are being offered for the account of other persons or entities as
well as the Company, such reduction shall not represent a greater fraction of
the number of Registrable Securities intended to be offered by the Holders than
the fraction of similar reductions imposed on such other persons or entities
(other than the Company).

     3.   Registration Expenses. In the event of a registration described in
          ---------------------
Section 2, all reasonable expenses of registration and of the offering effected
thereby of any Holder of Registrable Securities participating in the offering,
including, without limitation, printing expenses, fees and disbursements of
counsel and independent public accountants, counsel to the holders fees and
expenses (including counsel fees incurred in connection with complying with
state securities or "blue sky" laws, fees of the National Association of
Securities Dealers, Inc. and fees of transfer agents and registrars), shall be
borne by the Company, except that each

                                       3
<PAGE>

Holder of Registrable Securities shall bear underwriting commissions, individual
counsel fees, if any, and discounts attributable to such Holder's Registrable
Securities being registered.

     4.   Further Obligations of the Company. Whenever, under the preceding
          ----------------------------------
sections of this Agreement, the Company is required hereunder to register
Registrable Securities, it agrees that it shall also do the following:

          (a)  Unless and until the distribution of all Registrable Securities
requested to be registered under section 2 above is complete, diligently prepare
for filing with the Commission a registration statement and such amendments and
supplements to said registration statement and the prospectus used in connection
therewith as may be necessary to keep said registration statement effective for
a period of at least 120 days and to comply with the provisions of the
Securities Act with respect to the sale of securities covered by said
registration statement for the period necessary to complete the proposed public
offering;

          (b)  Furnish to any selling Holder of Registrable Securities such
copies of each preliminary and final prospectus and such other documents as such
Holder may reasonably request to facilitate the public offering of its
Registrable Securities;

          (c)  Enter into any underwriting agreement with provisions reasonably
required by the proposed underwriter for the selling Holder of Registrable
Securities, if any, and reasonably acceptable to the Company; and

          (d)  Register or qualify the Registrable Securities covered by said
registration statement under the securities or "blue-sky" laws of such
jurisdictions as the selling Holder of Registrable Securities may reasonably
request.

     5.   Indemnification
          ---------------

          (a)  Indemnification by the Company. The Company shall,
               ------------------------------
notwithstanding any termination of this Agreement, indemnify and hold harmless
each Holder, the officers, directors, agents (including any underwriters
retained by such Holder in connection with the offer and sale of Registrable
Securities), investment advisors and employees of each of them, each Person who
controls any such Holder (within the meaning of Section 15 of the Securities Act
or Section 20 of the Exchange Act) and the officers, directors, agents and
employees of each such controlling Person, to the fullest extent permitted by
applicable law, from and against any and all joint or several losses, claims,
damages, liabilities, costs (including, without limitation, costs of preparation
and attorneys' fees) and expenses (collectively, together with actions,
proceedings or inquiries by any regulatory or self-regulatory organization,
whether commenced or threatened, "Losses"), as incurred, arising out of or
                                  ------
relating to (i) any untrue or alleged untrue statement of a material fact
contained in the Registration Statement, any Prospectus or any form of
prospectus or in any amendment or supplement thereto or in any preliminary
Prospectus, or arising out of or relating to any omission or alleged omission of
a material fact required to be stated therein or necessary to make the
statements therein (in the case of any Prospectus or form of prospectus or
supplement thereto, in

                                       4
<PAGE>

light of the circumstances under which they were made) not misleading (in the
case of any Prospectus or form of prospectus or supplement thereto, in light of
the circumstances under which they were made), except to the extent, but only to
the extent, that such untrue statements or omissions are based upon and in
conformity with information regarding such Holder furnished in writing to the
Company by such Holder expressly for use therein, or (ii) any violation or
alleged violation by the Company of the Securities Act, the Exchange Act, any
other law, including, without limitation, any state securities law, or any rule
or regulation thereunder relating to the offer or sale of Registrable
Securities, provided, however, that the Company shall not be required to
indemnify any person with respect to a loss arising out of a sale of any
Registrable Securities during any period during which the Company has advised
the Holder to suspend sales pursuant to a registration statement. The Company
shall not, however, be liable for any Losses to any Holder with respect to any
untrue or alleged untrue statement of material fact or omission or alleged
omission of material fact if such statement or omission was made in a
preliminary Prospectus and such Holder did not receive a copy of the final
Prospectus (or any amendment or supplement thereto) at or prior to the
confirmation of the sale of the Registrable Securities in any case where such
delivery is required by the Securities Act and the untrue or alleged untrue
statement of material fact or omission or alleged omission of material fact
contained in such preliminary Prospectus was corrected in the final Prospectus
(or any amendment or supplement thereto) and such final prospectus was provided
by the Company to the Holder prior to the time of such sale. The Company shall
notify the Holders promptly of the institution, threat or assertion of any
Proceeding of which the Company is aware in connection with the transactions
contemplated by this Agreement.

          (b)  Indemnification by Holder. The Holder shall indemnify and hold
               -------------------------
harmless the Company, the directors, officers, agents and employees, each Person
who controls the Company (within the meaning of Section 15 of the Securities Act
and Section 20 of the Exchange Act), and the directors, officers, agents or
employees of such controlling Persons, to the fullest extent permitted by
applicable law, from and against all Losses, as incurred, arising solely out of
or based solely upon (i) any untrue statement of a material fact contained in
the Registration Statement, any Prospectus, or any form of prospectus, or
arising solely out of or based solely upon any omission of a material fact
required to be stated therein or necessary to make the statements therein not
misleading to the extent, but only to the extent, that such untrue statement or
omission is contained in any information so furnished in writing by such Holder
to the Company specifically for inclusion in the Registration Statement or such
Prospectus and that such information was reasonably relied upon by the Company
for use in the Registration Statement, such Prospectus or such form of
prospectus or to the extent that such information relates to such Holder or such
Holder's proposed method of distribution of Registrable Securities and was
reviewed and expressly approved in writing by such Holder expressly for use in
the Registration Statement, such Prospectus or such form of prospectus or (ii)
any violation or alleged violation by the Holders of the Securities Act, the
Exchange Act, any other law, including, without limitation, any state securities
law, or any rule or regulation thereunder relating to the offer or sale of
Registrable Securities; provided, however, that the indemnity agreement
                        --------  -------
contained in this Section 4(b) shall not apply to amounts paid in settlement of
any Losses if such settlement is effected without the prior written consent of
such Holder. In no event shall the liability of any selling Holder hereunder be
greater in amount than the dollar amount of the net proceeds received by such
Holder upon the sale of the Registrable Securities giving rise to such
indemnification obligation.

                                       5
<PAGE>

          (c)  Conduct of Indemnification Proceedings. If any Proceeding shall
               --------------------------------------
be brought or asserted against any Person entitled to indemnity hereunder (an
"Indemnified Party"), such Indemnified Party promptly shall notify the Person
 -----------------
from whom indemnity is sought (the "Indemnifying Party") in writing, and the
                                    ------------------
Indemnifying Party shall assume the defense thereof, including the employment of
counsel reasonably satisfactory to the Indemnified Party and the payment of all
fees and expenses incurred in connection with defense thereof; provided,
                                                               --------
however, that the failure of any Indemnified Party to give such notice shall not
-------
relieve the Indemnifying Party of its obligations or liabilities pursuant to
this Agreement, except (and only) to the extent that it shall be finally
determined by a court of competent jurisdiction (which determination is not
subject to appeal or further review) that such failure shall have proximately
and materially adversely prejudiced the Indemnifying Party.

          An Indemnified Party shall have the right to employ separate counsel
in any such Proceeding and to participate in the defense thereof, but the fees
and expenses of such counsel shall be at the expense of such Indemnified Party
or Parties unless: (1) the Indemnifying Party has agreed in writing to pay such
fees and expenses; or (2) the Indemnifying Party shall have failed promptly to
assume the defense of such Proceeding and to employ counsel reasonably
satisfactory to such Indemnified Party in any such Proceeding; or (3) the named
parties to any such Proceeding (including any impleaded parties) include both
such Indemnified Party and the Indemnifying Party, and such Indemnified Party
shall have been advised by counsel that a conflict of interest is likely to
exist if the same counsel were to represent such Indemnified Party and the
Indemnifying Party (in which case, if such Indemnified Party notifies the
Indemnifying Party in writing that it elects to employ separate counsel at the
expense of the Indemnifying Party, the Indemnifying Party shall not have the
right to assume the defense thereof and such counsel shall be at the expense of
the Indemnifying Party). The Indemnifying Party shall not be liable for any
settlement of any such Proceeding effected without its written consent, which
consent shall not be unreasonably withheld. No Indemnifying Party shall, without
the prior written consent of the Indemnified Party, effect any settlement of any
pending Proceeding in respect of which any Indemnified Party is a party, unless
such settlement includes an unconditional release of such Indemnified Party from
all liability on claims that are the subject matter of such Proceeding.

          All fees and expenses of the Indemnified Party (including reasonable
fees and expenses to the extent incurred in connection with investigating or
preparing to defend such Proceeding in a manner not inconsistent with this
Section) shall be paid to the Indemnified Party, as incurred, within ten (10)
Business Days of written notice thereof to the Indemnifying Party (regardless of
whether it is ultimately determined that an Indemnified Party is not entitled to
indemnification hereunder; provided, that the Indemnifying Party may require
such Indemnified Party to undertake to reimburse all such fees and expenses to
the extent it is finally judicially determined that such Indemnified Party is
not entitled to indemnification hereunder).

          (d)  Contribution. If a claim for indemnification under Section 4(a)
               ------------
or 4(b) is unavailable to an Indemnified Party because of a failure or refusal
of a court of competent jurisdiction to enforce such indemnification in
accordance with its terms (by reason of public policy or otherwise), then each
Indemnifying Party, in lieu of indemnifying such Indemnified

                                       6
<PAGE>

Party, shall contribute to the amount paid or payable by such Indemnified Party
as a result of such Losses, in such proportion as is appropriate to reflect the
relative fault of the Indemnifying Party and Indemnified Party in connection
with the actions, statements or omissions that resulted in such Losses as well
as any other relevant equitable considerations. The relative fault of such
Indemnifying Party and Indemnified Party shall be determined by reference to,
among other things, whether any action in question, including any untrue or
alleged untrue statement of a material fact or omission or alleged omission of a
material fact, has been taken or made by, or relates to information supplied by,
such Indemnifying Party or Indemnified Party, and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
action, statement or omission. The amount paid or payable by a party as a result
of any Losses shall be deemed to include, subject to the limitations set forth
in Section 4(c), any reasonable attorneys' or other reasonable fees or expenses
incurred by such party in connection with any Proceeding to the extent such
party would have been indemnified for such fees or expenses if the
indemnification provided for in this Section was available to such party in
accordance with its terms. In no event shall any selling Holder be required to
contribute an amount under this Section 4(d) in excess of the net proceeds
received by such Holder upon sale of the Registrable Securities pursuant to the
Registration Statement giving rise to such contribution obligation.

          The parties hereto agree that it would not be just and equitable if
contribution pursuant to this Section 4(d) were determined by pro rata
allocation or by any other method of allocation that does not take into account
the equitable considerations referred to in the immediately preceding paragraph.
No Person 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 guilty of such fraudulent misrepresentation.

          The indemnity and contribution agreements contained in this Section
are in addition to any liability that the Indemnifying Parties may have to the
Indemnified Parties.

     6.   Rule 144.
           --------

          During the period commencing on the date hereof and ending on the
second anniversary of the Secondary Closing (as defined in the Purchase
Agreement), as long as any Holder owns Registrable Securities, the Company
covenants to timely file (or obtain extensions in respect thereof and file
within the applicable grace period) all reports required to be filed by the
Company after the date hereof pursuant to Section 13(a) or l5(d) of the Exchange
Act. During the period commencing on the date hereof and ending on the second
anniversary of the Secondary Closing (as defined in the Purchase Agreement), as
long as any Holder owns Registrable Securities, if the Company is not required
to file reports pursuant to Section 13(a) or l5(d) of the Exchange Act, it will
prepare and furnish to the Holders and make publicly available in accordance
with Rule 144(c) promulgated under the Securities Act annual and quarterly
financial statements, together with a discussion and analysis of such financial
statements in form and substance substantially similar to those that would
otherwise be required to be included in reports required by Section 13(a) or
15(d) of the Exchange Act, as well as any other information required thereby, in
the time period that such filings would have been required to have been made
under the Exchange Act. The Company further covenants that it will use
commercially

                                       7
<PAGE>

reasonable efforts to take such further action as any Holder may reasonably
request, all to the extent required from time to time to enable such Person to
sell Underlying Shares without registration under the Securities Act within the
limitation of the exemptions provided by Rule 144 promulgated under the
Securities Act, including requesting of its counsel to provide any legal
opinions referred to in the Purchase Agreement. Upon the request of any Holder,
the Company shall deliver to such Holder a written certification of a duly
authorized officer as to whether it has complied with such requirements of this
Section 5.

     7.   Miscellaneous
          -------------

          (a)  Remedies. In the event of a breach by the Company or by a Holder
               --------
of any of their obligations under this Agreement, each Holder or the Company, as
the case may be, in addition to being entitled to exercise all rights granted by
law and under this Agreement, including recovery of damages, will be entitled to
specific performance of its rights under this Agreement. The Company and each
Holder agree that monetary damages would not provide adequate compensation for
any losses incurred by reason of a breach by it of any of the provisions of this
Agreement and hereby further agrees that, in the event of any action for
specific performance in respect of such breach, it shall waive the defense that
a remedy at law would be adequate.

          (b)  No Inconsistent Agreements. Neither the Company nor any of its
               --------------------------
subsidiaries has, as of the date hereof, nor shall the Company or any of its
subsidiaries, on or after the date of this Agreement, enter into any agreement
with respect to its securities that is inconsistent with the rights granted to
the Holder in this Agreement or otherwise conflicts with or limits the
provisions hereof. Neither the Company nor any of its subsidiaries currently has
in force or effect any agreement granting any registration rights with respect
to any of its securities to any Person. This Agreement, together with the
Purchase Agreement and SatCon Registration Rights Agreement, contain the entire
understanding of the parties with respect to the subject matter hereof and
supersede all prior agreements and understandings, oral or written, with respect
to such matters.

          (c)  Amendments and Waivers. The provisions of this Agreement,
               ----------------------
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given, unless the same shall be in writing and signed by the Company
and the Holders of at least two-thirds of the then outstanding Registrable
Securities; provided, however, that for the purposes of this sentence,
            --------  -------
Registrable Securities that are owned, directly or indirectly, by the Company,
or an Affiliate of the Company are not deemed outstanding. Notwithstanding the
foregoing, a waiver or consent to depart from the provisions hereof with respect
to a matter that relates exclusively to the rights of Holder and that does not
directly or indirectly affect the rights of other Holder may be given by Holders
of at least a majority of the Registrable Securities to which such waiver or
consent relates; provided, however, that the provisions of this sentence may not
                 --------  -------
be amended, modified, or supplemented except in accordance with the provisions
of the immediately preceding sentence.

          (d)  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

                                       8
<PAGE>

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 Purchaser to 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 & Dorr LLP,
60 State Street, Boston, MA 02109, Attn: Jeffrey N. Carp, Esq., fax no. (617)
526-5000 and (ii) if to Company to Mechanical Technology Incorporated, 968
Albany-Shaker Road, Latham, New York 12110. Attention: Chief Financial Officer
with copies to Catherine S. Hill, PLLC, 4 Global View, Troy, New York 12180
Attn: Catherine S. Hill, Esq., fax no. (518) 285-7564 or such other address as
may be designated in writing hereafter, in the same manner, by such Person.

          (e)  Successors and Assigns. This Agreement shall inure to the benefit
               ----------------------
of and be binding upon the successors and permitted assigns of each of the
parties and shall inure to the benefit of the Holder. The Company may not assign
its rights or obligations hereunder without the prior written consent of the
Holder. The Holder may assign its rights hereunder in the manner and to the
Persons as permitted under the Purchase Agreement. In addition, the rights of
the Holder hereunder, including the right to have the Company register for
resale Registrable Securities in accordance with the terms of this Agreement,
shall be automatically assignable by the Holder if: (i) the Holder agrees in
writing with the transferee or assignee to assign such rights, and a copy of
such agreement is furnished to the Company within a reasonable time after such
assignment, (ii) the Company is, within a reasonable time after such transfer or
assignment, furnished with written notice of (a) the name and address of such
transferee or assignee, and (b) the securities with respect to which such
registration rights are being transferred or assigned, (iii) following such
transfer or assignment the further disposition of such securities by the
transferee or assignees is restricted under the Securities Act and applicable
state securities laws, (iv) at or before the time the Company receives the
written notice contemplated by clause (ii) of this Section, the transferee or
assignee agrees in writing with the Company to be bound by all of the provisions
of this Agreement, and (v) such transfer shall have been made in accordance with
the applicable requirements of the Purchase Agreement. The rights to assignment
shall apply to the Holders (and to subsequent) successors and assigns.

          (f)  Counterparts. This Agreement may be executed in any number of
               ------------
counterparts, each of which when so executed shall be deemed to be an original
and all of which taken together shall constitute one and the same Agreement. In
the event that any signature is delivered by facsimile transmission, such
signature shall create a valid and binding obligation of the party executing (or
on whose behalf such signature is executed) the same with the same force and
effect as if such facsimile signature were the original thereof.

          (g)  Governing Law. The corporate laws of the State of New York shall
               -------------
govern all issues concerning the relative rights of the Company and the
Purchaser as its stockholders. All other questions concerning the construction,
validity, enforcement and

                                       9
<PAGE>

interpretation of this Agreement shall be governed by and construed in
accordance with the laws of the State of New York, without regard to principles
of conflicts of law. Each party hereby irrevocably submits to the non-exclusive
jurisdiction of the federal courts sitting in the City of Albany, County of
Albany, or if diversity jurisdiction cannot be obtained, then in the state
courts sitting in the City of Albany, County of Albany, 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 consent 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 Agreement 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.

          (h)  Cumulative Remedies. The remedies provided herein are cumulative
               -------------------
and not exclusive of any remedies provided by law.

          (i)  Severability. If any term, provision, covenant or restriction of
               ------------
this Agreement is held by a court of competent jurisdiction to be invalid,
illegal, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions set forth herein shall remain in full force and
effect and shall in no way be affected, impaired or invalidated, and the parties
hereto shall use their reasonable efforts to find and employ an alternative
means to achieve the same or substantially the same result as that contemplated
by such term, provision, covenant or restriction. It is hereby stipulated and
declared to be the intention of the parties that they would have executed the
remaining terms, provisions, covenants and restrictions without including any of
such that may be hereafter declared invalid, illegal, void or unenforceable.

          (j)  Headings. The headings in this Agreement are for convenience of
               --------
reference only and shall not limit or otherwise affect the meaning hereof.

          (k)  Shares Held by The Company and its Affiliates. Whenever the
               ---------------------------------------------
consent or approval of Holders of a specified percentage of Registrable
Securities is required hereunder, Registrable Securities held by the Company or
its Affiliates (other than any Holder or transferees or successors or assigns
thereof if such Holder is deemed to be an Affiliate solely by reason of its
holdings of such Registrable Securities) shall not be counted in determining
whether such consent or approval was given by the Holders of such required
percentage.

          (l)  Revision of SEC Position on Warrants. In the event the rules and
               ------------------------------------
regulations of the Commission or the policies of the staff of the Commission are
modified and as a result thereof the Company determines in good faith that it
may be practicable and in the interests of the Company and the Holders to
register the exercise of the Warrants so that the Warrant Shares may be freely
resold without maintaining an effective registration statement under the
Securities Act for resales, the Company and the Holders agree to cooperate in
good faith to effect such amendments to this Agreement as may be appropriate to
provide that the Company may fulfill its obligations hereunder with respect to
the Warrants and the Warrant

                                       10
<PAGE>

Shares by maintaining an effective registration statement under the Securities
Act covering the exercise of the Warrants rather than the resale of the Warrant
Shares.

                                       11
<PAGE>

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

                                       MECHANICAL TECHNOLOGY INCORPORATED


                                       By: /s/Cynthia A. Scheuer
                                           ----------------------------------
                                           Name: Cynthia A. Scheuer
                                           Title: Vice President and CFO


                                       SATCON TECHNOLOGY CORPORATION


                                       By: /s/ David B. Eisenhaure
                                           ----------------------------------
                                           Name: David B. Eisenhaure
                                           Title:  President

                                       12