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Combined Heat and Power Partnership

Maine Net-Metering Rules

Date Last Updated6/6/2014
Policy TypeNet-Metering Policy
Policy Administrator/Contact OfficeMaine Public Utilities Commission
Policy Initiation Date1/1/1987
Policy SummaryNet-metering is available to CHP that meets certain efficiency and size requirements. LD 336 adopted in April 2009 amended net metering rules, including high efficiency micro-CHP systems as eligible. Net metering had been available in Maine from 1987 to 1998 for qualified CHP and from 1987 until April 30, 2009 for other small power production facilities up to 100 kW. Micro-CHP systems are defined as a system that produces heat and electricity from one fuel input, without restriction to specific fuel or generating technology. Micro-CHP with an electric generating capacity rating of at least one kilowatt and not more than 30 kilowatts must achieve a combined electric and thermal efficiency of at least 80% or greater to qualify. In addition, micro-CHP 31 kW to 660 kW must achieve a combined efficiency of 65% or greater to qualify.

All of Maine's electric utilities -- investor-owned utilities, consumer-owned utilities (COUs), municipal utilities and electric cooperatives -- must offer net-metering to micro-CHP. IOUs are required to offer net metering for shared ownership customers, while COUs may offer net metering to shared ownership. "Shared ownership" allows for community net metering, where several people invest in an eligible system and are therefore allowed to benefit (see below for more information). IOUs are required to offer net metering to eligible facilities up to 660 kW. COUs are required to offer net metering to customers up to 100 kW, and are authorized, although subject to their discretion, to offer net metering to eligible facilities up to 660 kW.

Net excess generation (NEG) is credited to the following month for up to 12 months; after the end of an annualized period, all NEG is granted to the utility with no compensation for the customer. At its own expense, a utility may install additional meters to record purchases and sales separately. There is no limit on the aggregate amount of energy generated by net-metered customers. However, a utility must notify the PUC if the cumulative capacity of net-metered facilities reaches 1.0% of the utility's peak demand.
CHP Eligibility RequirementsBoth fossil-fueled and renewably-fueled CHP systems are eligible for net-metering.
Eligible Project Size (MW)Micro-CHP systems <660kW are eligible to net-meter. <100 MW for fuel cell CHP or anaerobic digester gas fueled CHP systems are potentially eligible to net-meter.
Minimum Efficiency Required/
Other Performance Requirements
Micro-CHP <30 kW must achieve combined electrical and thermal efficiency of 80% or greater, and micro-CHP systems between 30 kW and 660 kW must achieve combined efficiency of 65% or greater.
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