Portland, ME Solar Panels

Maine’s Net Energy Billing (NEB) program is the state’s primary solar incentive, allowing residential solar owners in Portland to receive a full 1:1 retail-rate credit for every kilowatt-hour (kWh) of excess electricity their solar panels send back to the grid. Credits are currently valued at approximately $0.27/kWh for Central Maine Power (CMP) customers and $0.32/kWh for Versant Power customers. These credits roll over month to month for up to 12 months, helping offset your electric bill year-round.

NEB is available to all Maine residential customers with a grid-connected rooftop solar system, including homeowners in Portland. There is no cap on residential participation, no application fee, and systems up to 660 kW qualify. The residential rooftop NEB program was not affected by recent 2026 legislative changes (LD 1777), which only impacted non-residential and community solar participants.

To enroll, simply contact your utility — Central Maine Power (CMP) or Versant Power — after your solar installation is complete and interconnected. Your utility will set up your NEB account and begin applying credits to your bill automatically. NEB is administered and overseen by the Maine Public Utilities Commission (PUC).

Maine’s Renewable Energy Investment Exemption ensures that installing solar panels will not increase your property tax bill. All qualifying renewable energy equipment — including solar panels, mounting racks, inverters, batteries used to store solar-generated electricity, charge controllers, and associated wiring — is 100% exempt from local property tax assessment. This is a statewide mandate that applies in every Maine municipality, including Portland, unlike some states where this is a local option.

For a typical 9 kW residential solar system, this exemption can save homeowners an estimated $381 or more per year in property taxes. Importantly, batteries used to store solar-generated electricity are explicitly included in the exemption, making it valuable for homeowners who add storage alongside their solar array. The exemption applies to both new installations and existing systems that have not yet claimed it.

The exemption is not automatic — you must apply with your local municipal assessor’s office by April 1 of the first year you wish to claim it. If you miss the April 1 deadline, the assessor may legally add the value of your solar equipment to your property assessment for that tax year. Contact your local assessor or visit the Maine Revenue Services website for the required application form.

Maine offers a sales tax exemption on solar energy equipment, meaning homeowners in Portland do not pay the state’s 5.5% sales tax on qualifying solar panel system components at the time of purchase. For a typical residential solar installation priced around $20,000, this exemption translates to approximately $1,100 in immediate upfront savings — a passive benefit that stacks on top of other Maine incentives like Net Energy Billing and the property tax exemption.

This exemption applies to solar equipment such as panels, inverters, and related components. Unlike the property tax exemption, no ongoing application is required from the homeowner — the savings are applied at the point of sale. However, it is important to verify with your solar installer before signing a contract that the exemption will be properly applied to your purchase.

For official confirmation of eligible equipment and current exemption rules, contact Maine Revenue Services or ask your installer to confirm the exemption applies to your specific system configuration. Always get written confirmation from your installer that the sales tax exemption has been applied to your contract.

Efficiency Maine’s Small Battery Incentive Program pays battery storage owners for participating in demand response events — periods of high electricity demand on the New England grid that typically occur 40 to 60 times between June 1 and September 30, with each event lasting no more than three hours. During these events, your battery automatically discharges to help reduce grid strain, and you are compensated based on the average kilowatts (kW) your battery delivers. The program pays approximately $180–$200 per kW of average discharge per year, with payments made annually.

To be eligible, your battery must be interconnected per your utility’s guidelines, and you must be on a Maine utility residential or small commercial rate (Small General Service or General Service). Importantly, solar generation is not required — battery-only installations qualify. Participants sign agreements with Efficiency Maine for up to 10 years per site, and enrollment can be managed through your installer or directly through Efficiency Maine.

As an example of potential earnings: if your battery discharges an average of 5 kW during all demand response events, Efficiency Maine pays $1,000 per year. Over a 10-year agreement, that could add up to $9,000 or more in total earnings, significantly improving the financial return on your battery storage investment. Contact Efficiency Maine at 1-866-376-2463 or visit their website to learn about current enrollment and to find participating installers.

Efficiency Maine’s Energy Storage System (ESS) Program provides substantial performance-based incentives for non-residential customers — including commercial businesses, nonprofits, institutions, and government entities — that install and operate battery storage systems in Maine. Incentive awards range from a minimum of $4,000 to a maximum of $600,000 per year, per project, paid over a 5-year performance period, making this one of the most significant battery storage incentives available to larger commercial and institutional customers in the state.

To be eligible, projects must be located in Maine, interconnected behind the facility’s utility meter, and have a Maine electric utility account. Battery systems must be at least 20 kW in capacity, maintain a minimum 80% round-trip efficiency, be able to collect and transmit 15-minute interval data, carry a 10-year manufacturer warranty, and be UL-listed or certified by another nationally recognized testing laboratory. Incentive payments are tied directly to actual performance during summer peak demand events.

This program is administered through a competitive Opportunity Notice (PON) process. Interested non-residential customers should contact Efficiency Maine directly at 1-866-376-2463 or email [email protected] to learn about current funding availability, application requirements, and a list of qualified battery vendors who can help customers participate in the program.