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Incentives/Policies for Renewables & Efficiency

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Net Energy Billing   

Last DSIRE Review: 09/02/2014
Program Overview:
State: Maine
Incentive Type: Net Metering
Eligible Renewable/Other Technologies: Solar Thermal Electric, Photovoltaics, Wind, Biomass, Hydroelectric, Geothermal Electric, Fuel Cells, Municipal Solid Waste, CHP/Cogeneration, Small Hydroelectric, Tidal Energy, Fuel Cells using Renewable Fuels
Applicable Sectors: Commercial, Industrial, Residential, Nonprofit, Schools, Multi-Family Residential, Low-Income Residential, Agricultural, Institutional
Applicable Utilities:All utilities
System Capacity Limit:660 kW for IOU customers; 100 kW for muni and co-op customers (munis and co-ops may voluntarily offer net energy billing for systems up to 660 kW)
Aggregate Capacity Limit:No limit specified
Net Excess Generation:Credited to customer's next bill at retail rate; granted to utility at end of 12-month billing cycle
REC Ownership:Not addressed
Meter Aggregation:Allowed
Authority 1:
Date Enacted:
CMR 65-407-313
12/10/1998 (subsequently amended)
Authority 2:
Date Enacted:
Date Effective:
Resolve, Chapter 20, 124th Legislature
Authority 3:
Date Enacted:
Date Effective:
35-A MRSA ยง3209-A
Authority 4:
Date Enacted:
S.P. 644

Eligibility and Availability

All of Maine's electric utilities -- investor-owned utilities (IOUs) and consumer-owned utilities (COUs), which include municipal utilities and electric cooperatives -- must offer net energy billing, otherwise known as net metering, for individual customers. Furthermore, IOUs are required to offer net metering for shared ownership customers, while COUs may offer net metering to shared ownership customers at their discretion. "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 with capacity limits up to 660 kilowatts (kW). COUs are required to offer net metering to customer-generators up to 100 kW, but, they are authorized to offer net metering to eligible facilities with capacity limits up to 660 kW at their discretion.

Net metering is available to owners of eligible, qualified facilities, including facilities generating electricity using fuel cells, tidal power, solar, wind, geothermal, hydroelectric, biomass, generators fueled by municipal solid waste in conjunction with recycling, and eligible combined heat and power (CHP) systems. It should be noted that the CHP systems must meet efficiency requirements in order to qualify for net metering: micro-CHP 30 kW and below must achieve combined electrical and thermal efficiency of 80% or greater, and micro-CHP 31 kW to 660 kW must achieve combined efficiency of 65% or greater.

Net Excess Generation

Net excess generation (NEG) is credited to the following month for up to 12 months; after the end of a 12-month period, any remaining 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 electricity generated by net-metered customers. However, a utility must notify the Maine Public Utilities Commission (PUC) if the cumulative capacity of net-metered facilities reaches 1.0% of the utility's peak demand.

Shared ownership customers must maintain ownership interest in an eligible facility. These customers share the responsibilities and costs of the facility and resulting proportional benefits. Up to 10 meters can be net metered against a single eligible facility. The shared ownership customers must designate one contact person to serve as the liaison between the owners and utility.

Value of Solar

The PUC must prepare a report, determining the value of distributed solar energy generation in the state of Maine by February 15, 2015. 


Net metering has been available in Maine from 1987 to 1998 for owners of qualified combined heat and power (CHP) systems and from 1987 until April 30, 2009 for owners of other small power-production facilities with a maximum capacity of 100 kilowatts (kW). When Maine's legislature enacted restructuring legislation that provided for retail competition beginning March 1, 2000, the Maine PUC amended the state's net-metering rules to make the rules consistent with changes to structure of the electric industry. The rules were modified to address issues related to existing contracts that extend beyond March 1, 2000.

However, in addressing net metering arrangements that took effect after the onset of retail access, the PUC decided that new rules would be more appropriate than the regulations already in place for cogeneration and small power-production facilities. Thus, the PUC issued new net metering rules that apply to the resources and technologies defined in the state's restructuring legislation: fuel cells, tidal power, solar, wind, geothermal, hydroelectric, biomass, and generators fueled by municipal solid waste in conjunction with recycling. CHP was not eligible at that time. It was also clarified that net energy billing was exempt from sales or use tax with respect to the sale or delivery of kilowatt hours of electricity to net energy billing customers as defined by the Public Utilities Commission for which no money is paid to the electricity provider or to the transmission and distribution utility (see MRSA Title 36, §1760, sub-§80).

The PUC issued an order amending net metering early 2009 in order to allow shared ownership, subject to legislative approval. In April 2009, Gov. John Baldacci signed L.D. 336, authorizing the final adoption of the rule, further amending it to include high efficiency micro-combined heat and power systems as eligible to net meter and to participate in the new shared ownership net metering opportunities and increasing the capacity limit from 500 kW (as in the proposed rules) to 660 kW.

  Mitchell Tannenbaum
Maine Public Utilities Commission
#18 State House Station
Augusta, ME 04333
Phone: (207) 287-3831
Web Site:
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Disclaimer: The information presented on the DSIRE web site provides an unofficial overview of financial incentives and other policies. It does not constitute professional tax advice or other professional financial guidance, and it should not be used as the only source of information when making purchasing decisions, investment decisions or tax decisions, or when executing other binding agreements. Please refer to the individual contact provided below each summary to verify that a specific financial incentive or other policy applies to your project.

While the DSIRE staff strives to provide the best information possible, the DSIRE staff, the N.C. Solar Center, N.C. State University and the Interstate Renewable Energy Council, Inc. make no representations or warranties, either express or implied, concerning the accuracy, completeness, reliability or suitability of the information. The DSIRE staff, the N.C. Solar Center, N.C. State University and the Interstate Renewable Energy Council, Inc. disclaim all liability of any kind arising out of your use or misuse of the information contained or referenced on DSIRE Web pages.

Copyright 2014 - 2015 North Carolina State University, under NREL Subcontract No. XEU-0-99515-01. Permission granted only for personal or educational use, or for use by or on behalf of the U.S. government. North Carolina State University prohibits the unauthorized display, reproduction, sale, and/or distribution of all or portions of the content of the Database of State Incentives for Renewables and Efficiency (DSIRE) without prior, written consent.