Commercial battery storage in Maine, with a five-year state check.
Maine pays commercial storage directly: Efficiency Maine's energy storage program awards $200 per kW of verified summer dispatch, every year for five years, for new systems approved before installation. Central Maine Power's time-of-use classes carry on-peak demand charges up to $48.51 per kW, and both CMP and Versant offer rate options that let a battery cut transmission on the coincident peak. Maine is a strong market with two conditions a lease has to satisfy, and KEEL prices it with both in view.
Utilities KEEL prices in Maine
Central Maine Power and Versant Power serve nearly all of the state. Both have default demand rates and an elective coincident-peak option that changes what a battery can earn.
| Utility | Rate classes | Demand charge as read | What it means for a battery |
|---|---|---|---|
| Central Maine Power | MGS-S (medium general service) | $19.98 per kW in July–August | Summer-weighted demand charge with no ratchet, so every month's saving stands on its own. |
| Central Maine Power | IGS-S-TOU / LGS-S-TOU | $34.11 / $48.51 per kW on-peak (weekdays 5–9 pm), effective July 2026 | A narrow evening on-peak window is ideal for a four-hour battery. No ratchet. |
| Central Maine Power | Rate B-CPT (coincident-peak transmission option) | Transmission rebilled at $24.50 per kW of monthly coincident peak, with base demand charges reduced | The mechanism by which a CMP battery monetizes the regional coincident peak. On standard schedules the utility keeps that saving. |
| Versant Power | M-1 (primary, 25–500 kW) and the DC Fast Charging and Storage Eco option | $34.19 per kW-month total default delivery demand; Eco option $31.77 per kW of coincident peak | Winter-peaking territory (November–February), the opposite season from the state storage program. Modeled on the account's own profile. |
Rates as read from the filed tariffs in August 2026. Utilities re-file often; KEEL re-reads the effective sheet on the day a project is priced.
What a battery earns in Maine
Efficiency Maine: $200 per kW a year, five years
Paid on the average kW delivered across fifteen three-hour summer dispatches. Program caps are $600,000 a year and $3 million over five years. After year five the system can re-apply at whatever rate, if any, is then offered.
Evening on-peak demand charges
CMP's TOU classes bill on-peak demand at $34.11 to $48.51 per kW in a 5–9 pm weekday window. A four-hour battery covers the whole window.
Coincident-peak transmission
Under CMP's B-CPT rate or Versant's Eco option, transmission is billed on the monthly coincident peak. Discharging into that hour cuts a line that standard schedules do not let the customer touch.
State and utility programs
Maine has a real state storage incentive with a defined term and a defined basis. It also has a condition on third-party ownership that KEEL resolves before it quotes.
| Program | What it pays | Who can claim it | Notes |
|---|---|---|---|
| Federal investment tax credit (§48E) | 30%+ of eligible cost: a 30% base (prevailing-wage rules apply at 1 MW and above) plus a 10-point adder for domestic content | The owner of the equipment; nonprofits and public bodies by direct pay | See the federal guide. |
| Efficiency Maine Energy Storage System program (PON EM-003-2027, open through June 30, 2027) | $200 per kW per year for five years, on the average kW across fifteen three-hour summer dispatches; caps of $600,000 per year and $3 million over five years | New systems approved before installation; retrofits are ineligible. Third-party financing is contemplated by the program; whether a leased system can hold or assign the award is not settled in the program documents (the rider carries a no-assignment clause on funded equipment), so KEEL obtains the Trust's written answer before pricing a lease on it. | The participant, not the utility, chooses when to dispatch, and dispatches outside the region's peak days are discarded. Forward-capacity-market rights are assigned to the Trust for the term, so ISO New England capacity revenue cannot be stacked. |
| Efficiency Maine Demand Response Program | Paid to aggregators per average kW | Aggregators; the customer's share is a private term | Not the storage program and not modeled. |
| ISO New England capacity market | No revenue available before mid-2028 | — | The next auction is delayed to 2028 and the prompt market starts June 2028. KEEL carries it at zero for now. |
Read from program documents and filed tariffs in August 2026. Programs open, fill and change; KEEL confirms each line against the live source before it goes in a proposal. The federal credit applies in every state on top of what is listed here, subject to the conditions in that guide.
What to watch in Maine
- The storage program pays for five years, not the life of the lease. KEEL models the incentive for the term it is paid and the lease on the savings that remain after it.
- Whether a leased system can hold or assign the incentive is not settled in the program documents. KEEL puts it to the Efficiency Maine Trust in writing before the lease is priced on it.
- Fifteen deep summer cycles a year for the program, plus daily peak shaving, is a real duty cycle. The battery is specified for it.
- Versant territory peaks in winter; the state program pays for summer. Versant projects are sized on the winter demand case and the summer program separately.
How KEEL prices a Maine project: model the CMP on-peak or Versant demand series from the bill, evaluate whether the account should elect the coincident-peak rate option, and add the Efficiency Maine incentive for five years at a dispatch performance the battery can hold across fifteen summer events. The incentive is included only once the Trust has approved the application and, under a lease, confirmed in writing that the leased system can hold it. ISO New England capacity is carried at zero until the market reopens.
What to send
Twelve months of electric bills for the meter you have in mind (interval data if you have it), the service address and the rate class printed on the bill. That is enough for a first read on demand charges, program eligibility and a monthly payment range. See Lease vs. Buy for how the numbers land under each structure, or schedule a property review.
Common questions
How much does Efficiency Maine pay for commercial battery storage?
$200 per kW of verified dispatch per year for five years, measured as the average kW delivered across fifteen three-hour summer dispatches, capped at $600,000 a year and $3 million over five years per project. The system must be approved before it is installed.
Can a leased battery get the Efficiency Maine incentive?
Not confirmed. The program contemplates third-party financing and does not prohibit leased systems, but it does not expressly permit them either, and its no-assignment clause on funded equipment may reach a leased system. KEEL puts the question to the Trust in writing before pricing a lease on the incentive.
Which Maine accounts pencil best?
CMP accounts on the IGS or LGS time-of-use classes with evening peaks, especially where the account can move to the coincident-peak transmission option, and any new construction or major renovation where the battery can be approved before installation.
Have a Maine building in mind?
Send the address and a bill. KEEL returns the demand-charge read, the program lines the site qualifies for and a monthly payment range, with the source for each.