Portland, ME Solar Panels

Maine’s Net Energy Billing (NEB) program is the primary financial incentive for residential solar owners in the state. For every kilowatt-hour (kWh) your solar panels send back to the grid, you receive a full retail-rate credit on your electric bill — currently $0.27/kWh for Central Maine Power (CMP) customers and $0.32/kWh for Versant Power customers. This 1:1 credit structure means you are compensated at the same rate you would otherwise pay for electricity, making rooftop solar highly effective at offsetting your energy costs.

Credits accumulate month to month and roll over throughout your billing year. At the end of the 12-month billing cycle, any remaining unused credits are compensated at the utility’s lower avoided-cost rate rather than the full retail rate, so it is best to size your system to avoid significant annual surpluses. Importantly, the residential rooftop NEB program was not affected by the 2026 legislative changes (LD 1777) that impacted community solar — your rooftop solar credits remain fully protected.

NEB is available to all Maine residential customers with a grid-connected rooftop solar system, regardless of which utility serves your home. Residents of Portland are served by Central Maine Power (CMP). To enroll, contact your utility after your solar installation is complete and interconnected. There is no cap on residential rooftop participation, and no application fee.

Maine’s Renewable Energy Investment Exemption, effective April 1, 2020, ensures that installing solar panels or a battery storage system on your home will not raise 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, meaning it applies in every Maine municipality, including Portland. For a typical 9 kW solar system, this exemption can save homeowners an estimated $381 or more per year in property taxes.

Eligible equipment covers the full solar and storage system: panels, racking hardware, inverters, battery storage units, charge controllers, and all directly related components. The exemption applies to both new installations and existing systems that have not yet claimed it. Batteries used to store solar-generated electricity are explicitly included, making this exemption valuable for homeowners adding storage alongside their solar array.

To claim the exemption, you must submit an application to your local town or city assessor’s office by April 1 of the first year you wish to receive it. The application is a simple one-time filing — once approved, the exemption remains in place for as long as you own the qualifying equipment. Contact your local municipal office or Maine Revenue Services for the appropriate application form.

Maine provides a sales tax exemption on the purchase of solar energy equipment, meaning you will not pay the state’s 5.5% sales tax on solar panels and related system components at the time of purchase. For a typical residential solar installation costing around $20,000, this exemption translates to an immediate upfront savings of approximately $1,100. The exemption is designed to lower the barrier to solar adoption by reducing the out-of-pocket cost of going solar.

The exemption covers solar panels, inverters, mounting hardware, and other directly related system components. In most cases, the exemption is applied automatically at the point of sale by your solar installer — there is no separate rebate application or reimbursement process required on the homeowner’s part. However, it is recommended that you confirm with your installer that the exemption is being applied correctly to your purchase, as application practices can vary.

This is a passive savings that stacks on top of other Maine incentives such as the property tax exemption and Net Energy Billing. While it does not require any ongoing action from the homeowner, verifying the exemption with your installer before signing a contract ensures you receive the full financial benefit from day one of your solar investment.

Efficiency Maine’s Small Battery Incentive Program compensates battery storage owners for participating in demand response events — periods of high electricity demand on the New England grid, typically occurring 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 paid for the energy you contribute. The program pays $200 per year for each average kilowatt (kW) discharged during these events, with payments made annually.

As a practical example, if your battery discharges an average of 5 kW during all demand response events, Efficiency Maine pays the Program Partner (typically your installer or a third-party aggregator) $1,000 per year. If the Program Partner passes on 90% of that incentive to you, you would earn $900 per year — and over a 10-year agreement, that adds up to $9,000 in total earnings. Popular eligible battery systems include the Tesla Powerwall, SolarEdge Home Battery, Enphase, and Generac, among others.

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). Solar generation is not required — battery-only installations qualify. Program Partners sign 10-year agreements with Efficiency Maine, and enrollment is managed through your installer or directly via the Efficiency Maine website. Contact Efficiency Maine at 1-866-376-2463 or visit their website for current enrollment details.

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. The program is designed to reduce peak electricity demand on the New England grid during summer months, and incentive payments are tied directly to actual performance during peak demand events.

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 and maintain a minimum 80% round-trip efficiency. Incentive awards range from a minimum of $4,000 to a maximum of $600,000 per year, per project, paid over a 5-year period — making this one of the most significant battery storage incentives available to larger commercial and institutional customers in the state.

To apply or learn more about current funding opportunities and program requirements, contact Efficiency Maine directly at 1-866-376-2463 or email [email protected]. Program funding is subject to availability, and projects are evaluated on a competitive basis through Efficiency Maine’s Opportunity Notice process.

The Maine Energy Solar for All (MESA) program is a federally funded initiative backed by an EPA Solar for All grant, originally awarded at $62 million, aimed at expanding solar and battery storage access to low-income and disadvantaged communities across Maine. The program is designed to serve over 20,000 eligible households and is expected to deliver estimated annual energy bill savings of between $380 and $1,400 per participating household, depending on system size and energy usage.

MESA will operate through four financial assistance channels: single-family on-site solar, multifamily on-site solar, cooperatively owned community solar, and a new community solar-plus-storage program. Energy storage is incorporated across all four channels to maximize both resilience and bill savings for participants. The program targets households that have historically been unable to access solar due to upfront cost barriers or housing type limitations.

As of early 2026, the program’s implementation status has been subject to change due to federal funding developments — residents of Portland who believe they may qualify should closely monitor the Maine Department of Energy Resources website for the latest announcements, application openings, income eligibility thresholds, and approved installer lists. Visit the official program page or contact the Maine Governor’s Energy Office for the most current information.