Maine Net Energy Billing: Credits, Enrollment, and Exemptions

Maine’s Net Energy Billing program lets utility customers offset their electricity bills by earning credits for surplus power their renewable systems send to the grid. Residential customers earn kilowatt-hour credits on a one-for-one basis. Commercial and institutional customers earn dollar-valued credits based on a tariff rate set by the Maine Public Utilities Commission. Credits roll over from month to month but expire after 12 months, so sizing a system to match actual annual use matters more than most homeowners realize.

How Credits Are Calculated

Maine uses two credit models. Which one applies depends on who owns the account.

Residential: Kilowatt-Hour Credits

Residential customers, and any shared-interest project that includes residential accounts, use the kilowatt-hour credit model. Each billing period, the utility tracks the difference between the electricity delivered to you and the electricity your system exports. If you export more than you use, the surplus carries forward as a kilowatt-hour credit on your next bill.¹ One kilowatt-hour exported equals one kilowatt-hour credited back.²

Commercial and Institutional: Tariff Rate Credits

Commercial and institutional customers receive a dollar-valued bill credit calculated by multiplying the customer’s share of facility output by a tariff rate. That rate equals the standard offer supply rate plus 75% of the effective transmission and distribution rate for the utility’s smallest commercial customer class.¹ The credit applies against the total bill but cannot push the bill below zero.³

A shared-interest project cannot mix the two. If any residential customers participate, the project uses the kilowatt-hour model. Only projects made up entirely of commercial or institutional accounts may use the tariff rate model.¹

The 12-Month Expiration

Under both models, unused credits expire after 12 months.⁴ You cannot cash them out. They exist to offset your electricity bill and nothing else.⁵ Oversizing a system beyond your annual usage adds no financial value. Aim to generate roughly what you consume over 12 months.

Who and What Qualifies

Your facility must use a renewable fuel or technology recognized under Maine’s renewable portfolio standards. Eligible sources include solar, wind, tidal power, geothermal, hydroelectric, biomass fueled by wood or wood waste, landfill gas, anaerobic digestion of agricultural products, and generators fueled by municipal solid waste paired with recycling. Fuel cells also qualify. Micro-combined heat and power systems are no longer eligible.⁵

By statute, a distributed generation resource used for NEB must have a nameplate capacity of less than 5 megawatts. Municipalities get a narrow exception: the facility can be 5 MW or larger as long as less than 5 MW of metered electricity from it goes toward NEB.² Your utility may impose stricter limits through its interconnection process, so confirm with Central Maine Power or Versant Power before finalizing a system design.

How to Enroll

The path in depends on whether you own the system or subscribe to someone else’s.

If You Install Your Own System

Owner-installed systems require two parallel tracks: interconnection approval and an NEB agreement. Interconnection is governed by PUC Chapter 324. You submit an application to your utility describing the facility, its nameplate capacity, a site plan, and a one-line electrical diagram. The system must comply with IEEE 1547 standards, and the utility can require you to install protective equipment at your expense if grid safety demands it.⁶

General liability insurance is required, though the utility can waive it for systems with a nameplate capacity of 20 kilowatts or less.⁶ Once the system passes inspection and you receive a Certificate of Completion, CMP or Versant Power activates your NEB billing arrangement.⁷

If You Subscribe to Community Solar

Community solar subscribers install nothing. The project sponsor handles interconnection and utility communications, and submits documentation showing each subscriber has a valid financial interest in the facility. That interest can take the form of an ownership agreement, lease, power purchase agreement, or affidavit.⁷

Entities marketing community solar to residential and small commercial customers must register with the PUC and provide a standardized NEB Disclosure Form explaining costs and benefits before you sign anything.⁴ That disclosure must include a plain-language explanation of transfer and termination requirements.¹ Read it carefully. It is the closest thing to a consumer protection safety net you get before committing.

Community Solar and Shared Ownership

Shared-interest projects let multiple customers split the credits from a single renewable facility, which opens the program to renters, condo owners, and anyone whose property cannot host panels. In CMP’s territory (southern and central Maine), projects can serve any number of customers. In the northern Maine territory served by Versant Power, participation is capped at 10 accounts or meters per project unless the PUC determines the utility’s billing system can handle more.²

Legal structures vary. Some projects are cooperatives with formal bylaws and member ownership. Others are managed by third-party developers who sell subscriptions, typically for a monthly fee or per-kilowatt-hour rate that runs below the value of the credits you receive, producing net savings. Either way, the project sponsor is the utility’s contact and is responsible for reporting subscriber allocation changes.¹

Property Tax Exemption for Solar Equipment

Maine exempts qualifying solar energy equipment from property tax. For tax years beginning on or after April 1, 2025, the exemption applies to solar equipment that generates heat or electricity if the energy is used on-site, if the equipment is collocated with an NEB customer subscribed to at least 50% of the facility’s output, or if the energy runs through a utility and the generator had a fully executed interconnection agreement before June 1, 2024.⁸

The exemption covers equipment that generates the electricity or is necessary for generation: panels, racks, mounting hardware, inverters, batteries, charge controllers, and requisite wiring. It does not cover meters, control panels, or transmission lines running between the inverter and the grid. Land is never exempt, regardless of what sits on it.⁹

To claim the exemption, file a report with your local assessor on or before April 1 of the first tax year you claim it, using a form prescribed by the State Tax Assessor.⁸ Equipment still under construction and not yet operational on April 1 does not qualify for that tax year.⁹

Federal Tax Credit: An Important Boundary

The federal Residential Clean Energy Credit under Section 25D of the Internal Revenue Code, which provided a 30% tax credit for residential solar installations, no longer applies to expenditures made after December 31, 2025.¹⁰ If you installed a system in 2025 or earlier, you may still claim the credit on that year’s return. For new residential installations in 2026, the federal credit is gone.

NEB credits themselves are generally not taxable income for residential customers, because they offset your bill rather than paying you cash. If your utility instead issues a check for surplus energy, that payment could be treated as income depending on the amount and program structure.

Moving, Selling, or Leaving the Program

NEB credits attach to your billing account, not your address, which complicates moves and sales.

If You Sell a Home With a System

The sale does not automatically transfer the NEB account. The buyer must submit a fresh application to the utility. Any credits banked under your account that go unused before the account closes will expire. If the system is subject to a lease or loan, the financing company will typically hold a UCC filing on the equipment that has to be resolved during the sale.

If You Subscribe to Community Solar

Any subscriber may transfer or assign their interest to the project sponsor or to any person eligible to participate. Sponsors must provide a transfer process and cannot charge transfer fees when a subscriber moves within the same utility service territory.¹ The practical ease depends on your subscription contract. Some allow smooth reassignment; others impose early termination fees or require you to find a replacement subscriber. Read the contract before assuming you can walk away without cost.

Unused Credits at Termination

Termination generally means forfeiting any banked credits. Maine law does not require utilities to refund or cash out balances when an account closes. If you know you are leaving, try to run your credit bank down before you go.

Resolving Disputes

Billing errors, incorrect credit allocations, and delayed credits are the most common problems participants encounter. Contact your utility’s customer service first. Both CMP and Versant Power have review processes, and many issues are resolved at that stage.

If the utility does not resolve the complaint, you can file a formal complaint with the PUC’s Consumer Assistance and Safety Division, which investigates billing disputes, service quality, and proper application of rates. The division will notify you in writing or by phone of its decision, the reasoning, and your options for further action.¹¹

Community solar subscription disputes are harder. The PUC handles consumer protection complaints tied to NEB, but disagreements over subscription fees, allocation calculations, or early termination penalties are often governed by private contract law. If PUC mediation does not settle it, arbitration or civil litigation may be your route, depending on what the contract requires. That is one more reason to read every line of a community solar agreement before signing, especially the sections on fees, credit allocation, and dispute resolution.

1
Maine Public Utilities Commission. Maine Public Utilities Commission Chapter 313 – Customer Net Energy Billing
2
Maine Legislature. Maine Code Title 35-A 3209-A – Net Energy Billing
3
Maine Legislature. Maine Code Title 35-A 3209-B – Commercial and Institutional Net Energy Billing
4
Maine Public Utilities Commission. Net Energy Billing
5
Central Maine Power. Net Energy Billing
6
Maine Public Utilities Commission. Maine Public Utilities Commission Chapter 324 – Small Generator Interconnection Procedures
7
Central Maine Power. Central Maine Power Chapter 313 Customer Net Energy Billing Agreement Application
8
Maine Legislature. Maine Code Title 36 655 – Personal Property
9
Maine Revenue Services. Maine Revenue Services Property Tax Division Bulletin No. 29 – Solar Energy Equipment
10
Office of the Law Revision Counsel. 26 USC 25D – Residential Clean Energy Credit
11
Maine Public Utilities Commission. File a Consumer Complaint