Section 20. (a) The department shall require a mandatory charge of 0.5 mill per kilowatt-hour for all electricity consumers, except those served by a municipal lighting plant which does not supply generation service outside its own service territory or does not open its service territory to competition at the retail level, to support the development and promotion of renewable energy projects. All revenues generated by the mandatory charge shall be deposited into the Massachusetts Renewable Energy Trust Fund, established under section 9 of chapter 23J.

(b) Notwithstanding any general or special law to the contrary: (1) a municipal lighting plant which does not supply generation service outside its own service territory or does not open its service territory to competition may elect to assess and remit a mandatory charge per kilowatt-hour upon its electricity consumers on the same terms and conditions as apply to the charge imposed on consumers residing in competitive distribution service territories under this section; provided, however, that such an election by a municipal lighting plant shall be irrevocable and such a municipal lighting plant shall not be deemed to be supplying generation service outside its service territory or opening its service territory to competition at the retail level for the purposes of the first sentence of subsection (a); and (2) in administering the Massachusetts Renewable Energy Trust Fund, the Massachusetts clean energy technology center, shall not make any grant or loan or provide any subsidy from the trust fund to any municipal lighting plant or consumer residing in the distribution service territory of such municipal lighting plant unless: (A) a mandatory charge per kilowatt-hour is assessed against all consumers residing in the distribution service territory and remitted to the collaborative under the first sentence of subsection (a) or clause (1); or (B) the board of directors of the Massachusetts clean energy technology center, as a condition precedent to any such grant, loan or subsidy, shall have determined and incorporated into the minutes of its proceedings findings that: (i) any such grant, loan or subsidy is intended for the principal purpose of generating public benefits for those consumers who reside in distribution service territories in which the mandatory charge is so imposed and remitted and will generate only incidental private benefits to the recipient or others residing in a distribution service territory in which the mandatory charge is not so imposed and remitted; and (ii) the facts and circumstances associated with the recipient or the residence of the recipient provide unique or extraordinary opportunities to advance the public purposes of the trust fund over those opportunities available through grants or subsidies made to recipients residing in distribution service territories in which such a mandatory charge is assessed and remitted.