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Commercial Solar EPC in Maine

Ferrius Energy is a commercial solar and battery storage EPC serving Maine businesses, institutions, and developers in Central Maine Power and Versant Power territory. In 2026 the Maine opportunity is behind-the-meter: after the 2025 Net Energy Billing reforms, new projects are valued mainly on on-site consumption, collocated crediting, and demand reduction rather than remote community-style credits.

That changes how a Maine project should be scoped. We engineer, procure, build, and maintain rooftop, carport, and ground-mount systems sized to the host's load, designed for Maine snow and ice, and modeled against the credit mechanism that actually applies to a project interconnecting today.

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Last reviewed: September 2026. Net Energy Billing rules, tariff rates, and the successor program are changing; confirm current status with the Maine Public Utilities Commission and the Maine Department of Energy Resources before relying on any figure.

What changed in Maine: Net Energy Billing after LD 1777

Maine does not use the term net metering. Its mechanism is Net Energy Billing (NEB), set out in 35-A M.R.S. section 3209-A (the kWh credit program) and section 3209-B (the commercial and institutional program, commonly called the tariff rate program). The program grew fast: coverage of the 2025 reform reported Maine distributed generation expanding from 88 MWac in 2019 to 936 MWac in 2025, and ratepayer cost became the central political issue.

The Legislature responded with LD 1777, enacted as Public Law 2025, chapter 430 and effective September 24, 2025. For a commercial owner evaluating a project in 2026, the provisions that matter are these:

  • No new front-of-the-meter NEB. After December 31, 2025, the PUC may not allow a utility to enter into a NEB agreement with a generator that is interconnected, or planned to be interconnected, on the utility side of a customer's meter. Standalone "sell the credits to offtakers" projects are closed to new entrants.
  • Tariff rate program is collocated only. Since the end of 2023, a new resource can use the commercial tariff rate program only if it is collocated with all of its NEB customers and those customers subscribe to 100 percent of the output. Projects with NEB agreements executed on or before December 31, 2023 are grandfathered on this point.
  • Tariff rate formula reset. Through 2025 the rate for most projects equaled the standard offer supply rate plus 75 percent of the effective T&D rate of the smallest commercial class. From January 1, 2026 the rate is fixed at a base (the 2025 rate for resources under 3 MW; the escalating legacy rate for 3 to 5 MW resources) and increases 2.25 percent per year beginning January 1, 2027.
  • Size and term. Both NEB programs remain limited to resources under 5 MW, and an eligible tariff rate customer keeps credits for no less than 20 years from first credit.

The PUC publishes the tariff rates annually by utility and rate class. We do not quote a 2026 cents-per-kWh figure here because it depends on the customer's rate class and utility; we pull the currently published rate into the model for each site.

What this means in practice. A Maine project we scope in 2026 is almost always a behind-the-meter system on the customer's own premises. Energy consumed on site avoids the full delivered rate, which is where the value concentrates. Exported kWh are handled under whichever NEB program the project qualifies for, and the model should not assume the pre-2025 economics.

Credit Mechanics

kWh credit program vs. commercial tariff rate program

The two NEB structures reward different load profiles, and the choice is an engineering decision as much as a financial one.

kWh credit program

Available to all customer classes. Exported energy earns kilowatt-hour credits that offset kWh on later bills; unused credits expire after 12 months, and the value of expired credits is remitted to low-income assistance programs. Best suited to a building whose annual consumption comfortably exceeds annual production, so few credits expire.

Commercial tariff rate program

Nonresidential customers only. Exports earn a dollar bill credit at the PUC-set tariff rate, applicable to any portion of the bill, carried forward up to one year. For a new project the array must be collocated with its subscribers and 100 percent subscribed. Useful where seasonal load leaves exports stranded under kWh crediting.

Northern Maine limit

In the Versant Power Maine Public District, served by the northern Maine system administrator rather than ISO-NE, shared tariff rate projects are limited to 10 accounts or meters unless the PUC finds the billing system can handle more.

The successor program: status in September 2026

LD 1777 directed the state to design a replacement for front-of-the-meter distributed generation. Under Public Law 2025, chapter 430 and 35-A M.R.S. section 3209-I, the Maine Department of Energy Resources (DOER) published a draft Front-of-the-Meter Distributed Energy Resources program on August 27, 2026, held public webinars on June 25 and September 2, 2026, and took written comments through September 11, 2026. DOER must submit the proposed program to the PUC by September 30, 2026.

As described publicly, the draft has two parts: projects selling energy to standard offer providers under longer-term arrangements, and projects sited where distribution equipment is stressed so that generation can defer utility upgrades. The PUC may implement a program only if it finds benefits to ratepayers exceed costs. There is no published compensation rate, capacity block, or start date yet.

Our position. We do not underwrite a Maine ground-mount or community-scale project on successor-program revenue until the PUC acts. If you hold land or a site that only works as front-of-the-meter, we can carry engineering and interconnection work to a decision point and hold procurement until the rules are final. Confirm current status with DOER and the PUC.

Utilities and interconnection

Most commercial load in Maine sits in two investor-owned territories. Central Maine Power (CMP) serves the southern and central part of the state, including Portland, Lewiston, and Augusta. Versant Power serves the Bangor Hydro District in eastern Maine and the Maine Public District in Aroostook County, which is not connected to ISO-NE and is administered separately. Consumer-owned utilities and municipal systems serve smaller areas and are not covered by the investor-owned NEB statutes in the same way, so rules there need to be checked utility by utility.

Interconnection of generators up to the small generator threshold follows MPUC Chapter 324, the Small Generator Interconnection Procedures, which the PUC has amended in recent years in response to queue congestion. CMP and Versant each publish application procedures and hosting information. For a behind-the-meter array the practical items we manage are:

  • Hosting capacity screen. We review the utility's published circuit data before layout, because a feeder with little remaining capacity can force export limiting or trigger a study and upgrade cost.
  • Export control options. Where the credit value of exports is low or the circuit is constrained, a non-export or limited-export design with power control can shorten review and preserve most of the on-site value.
  • Service equipment. Older Maine mills and schools often need switchgear work at the point of interconnection; we price it in the feasibility stage, not after contract.
  • Permission to operate. PTO timing is driven by utility witness testing and meter work; we schedule commissioning around it so the system is not idle.
Economics

Incentives and tax treatment in Maine

Maine has no state solar tax credit or SREC market for commercial systems. Project returns rest on avoided utility cost, NEB crediting, federal tax benefits, and property tax treatment.

Federal Section 48E credit and depreciation

The clean electricity investment credit is 6 percent base and 30 percent for facilities under 1 MW AC net output or those meeting prevailing wage and apprenticeship rules. Under the One Big Beautiful Bill Act (enacted July 4, 2025), solar facilities that began construction on or before July 4, 2026 are not subject to the 2027 placed-in-service deadline, subject to continuity rules; facilities beginning construction after July 4, 2026 must be placed in service by December 31, 2027. That deadline is tight for a Maine project that starts now, given winter construction windows. Details are in our guide to the federal ITC and state incentives. Commercial solar is 5-year MACRS property, and 100 percent bonus depreciation was made permanent in 2025.

Solar property tax exemption and BETE

Maine Revenue Services Property Tax Bulletin No. 29 explains the solar energy equipment exemption in 36 M.R.S. sections 655(1)(U) and (V) and 656(1)(K) and (L), effective for assessments on or after April 1, 2025. It covers equipment that generates electricity, is necessary for generation, or converts it into usable form: panels, inverters, racking, batteries, charge controllers, and associated wiring. Meters, control panels, transmission lines, and land are excluded. Eligibility depends on how the energy is used, for example all energy used on site, or collocation with NEB customers subscribed to at least 50 percent of output, with interconnection agreement timing affecting commercial arrays.

Property eligible for the solar exemption is generally not eligible for the Business Equipment Tax Exemption (BETE), with a limited exception for arrays under construction. The owner files an application with the local assessor on or before April 1 of the first year the exemption is claimed. We flag this date in the closeout package because a missed filing costs a full year of exemption.

Designing for Maine snow, ice, and cold

Maine adopted the 2021 editions of the model codes in the Maine Uniform Building and Energy Code (MUBEC), effective April 7, 2025. Structural loads on arrays and host roofs follow those codes and ASCE 7 snow provisions, and design ground snow loads rise quickly moving inland and north. A system that works in coastal Massachusetts can be under-designed in Bangor or Presque Isle.

  • Roof capacity first. Solar adds dead load and changes how snow drifts and slides. We start with a structural review of the existing roof, including drift at parapets and step-downs, before committing to a layout.
  • Tilt and clearance. On ground mounts we raise the lower panel edge so shed snow has somewhere to go, and use steeper tilt where the site allows, which also helps winter production.
  • Carports and snow shedding. Canopies over parking need snow guards or a shedding path that keeps ice off vehicles and walkways; this drives orientation as much as yield does.
  • Cold-temperature string sizing. Module voltage rises in extreme cold. String lengths are set against the site's record low temperature so inverters are not over-voltaged on January mornings.
  • Winter production in the model. Snow cover reduces December to February output. Our energy model applies a snow loss assumption instead of an optimistic clear-panel estimate, so lenders and owners see realistic figures.

Commercial battery storage in Maine

With exports now worth less than on-site consumption, batteries do more work in Maine than they did under the old NEB structure. A commercial battery can store midday surplus for use in the evening, and it can reduce the monthly demand charge that makes up a large part of many CMP and Versant commercial bills. Storage also provides backup for critical loads, which matters in a state where winter storms and ice regularly cause outages.

Batteries charged from on-site solar can qualify for the federal investment credit, and battery equipment is listed among the items covered by the Maine solar property tax exemption when installed as part of an eligible array. We size storage from interval data: 15-minute demand history, the utility rate schedule, and the resilience goal. See our commercial battery storage services and our analysis of commercial BESS cost and ROI.

Where the numbers work in Maine

The strongest Maine candidates share a steady daytime or year-round load and a structurally sound roof or usable land next to the meter:

How We Work

A Maine project, start to PTO

Ferrius is headquartered in Saugus, Massachusetts, and delivers Maine projects under a single commercial solar EPC contract with in-house engineering, procurement, and construction, followed by operations and maintenance.

1. Feasibility

Twelve months of bills and interval data, roof or site review, hosting capacity screen, and a first pass at which NEB program applies.

2. Engineering and model

Structural analysis for Maine snow loads, single-line design, and a financial model with IRR, NPV, and payback under current tariff rules and the federal credit.

3. Interconnection and permits

Chapter 324 application with CMP or Versant, local building and electrical permits, and the NEB agreement paperwork.

4. Build, PTO, closeout

Construction planned around winter and operations, commissioning, utility PTO, and a closeout file that includes the April 1 property tax exemption filing.

Questions

Frequently asked questions

Can a new commercial solar project in Maine still use Net Energy Billing in 2026?

Yes, if it is behind the customer's meter. Under LD 1777 (Public Law 2025, chapter 430), after December 31, 2025 utilities may not sign NEB agreements with generators interconnected on the utility side of a customer's meter. A new commercial tariff rate project must also be collocated with its customers, who must subscribe to 100 percent of the output. Confirm eligibility with your utility and the Maine PUC.

What is the difference between the kWh credit program and the tariff rate program?

The kWh credit program, open to all customers, gives kilowatt-hour credits for exports that expire after 12 months. The commercial and institutional tariff rate program, for nonresidential customers, gives dollar credits at a PUC-set rate that can be applied to any part of the bill and carried forward up to one year. From 2026 the tariff rate is fixed at a base and escalates 2.25 percent per year starting January 1, 2027.

Is commercial solar equipment exempt from property tax in Maine?

Often yes. Maine exempts qualifying solar energy equipment, including panels, inverters, racking, and batteries, under 36 M.R.S. sections 655 and 656 for assessments on or after April 1, 2025, depending on how the energy is used. Such property is generally not eligible for BETE. The owner must file with the local assessor by April 1 of the first year claimed.

What is the status of Maine's successor distributed generation program?

The Maine Department of Energy Resources published a draft Front-of-the-Meter Distributed Energy Resources program on August 27, 2026, took comments through September 11, and must submit it to the PUC by September 30, 2026. The PUC may implement it only if ratepayer benefits exceed costs. No compensation rate or start date is final as of September 2026.

How do Maine snow loads affect a commercial solar design?

They drive the structural review, racking selection, tilt, and ground clearance. Maine applies the 2021 model codes through MUBEC, and design snow loads increase inland and north. We check roof capacity including drift, size strings for extreme cold, and include snow losses in the production model.

Sources

  • Maine Revisor of Statutes, Title 35-A, section 3209-A: Net energy billing. legislature.maine.gov
  • Maine Revisor of Statutes, Title 35-A, section 3209-B: Commercial and institutional net energy billing. legislature.maine.gov
  • Maine Public Utilities Commission, Net Energy Billing. maine.gov/mpuc
  • Maine Department of Energy Resources, Solar. maine.gov/energy
  • Maine Department of Energy Resources, Front of the Meter Distributed Energy Resources Program. maine.gov/energy
  • Maine Morning Star, Energy department proposes new plan to encourage renewable projects cut out of net energy billing (September 8, 2026). mainemorningstar.com
  • Maine Senate Democrats, New, balanced reforms to Net Energy Billing program to take effect. mainesenate.org
  • pv magazine USA, Maine's governor signs controversial net-metering reforms into law (June 30, 2025). pv-magazine-usa.com
  • Maine Revenue Services, Property Tax Bulletin No. 29: Solar energy equipment exemption. maine.gov/revenue
  • AIA Maine, Updated Maine Building Codes: MUBEC 2021 adoption effective April 7, 2025. aiamaine.org
  • Central Maine Power, Interconnection. cmpco.com
  • Versant Power, Distribution and Interconnection Process. versantpower.com
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