Efficiency Maine Small Battery Program
Earn annual payments by sharing your battery’s stored energy with the Maine grid — year-round.
What Is the Efficiency Maine Small Battery Program?
The Efficiency Maine Small Battery Program is a grid services initiative that rewards Maine homeowners for sharing stored energy from their home battery during periods of peak electricity demand. When Efficiency Maine calls a dispatch event, Fortress Power, operating as a Program Partner through Flip Energy, automatically signals your battery to discharge stored energy to the grid. In return, you earn an annual payment based on your battery’s average kilowatt contribution across all events during the program year.
The program runs year-round from April 1 through March 31, and Efficiency Maine signs 10-year contracts with Program Partners. Residential and small business customers on a Maine utility residential or small general service rate are eligible to participate.
Program Incentives
Annual Performance Payment
You can earn incentives based on your battery system’s average kilowatt (kW) discharge over the course of all of the year’s peak demand events
$180 / kW
Per Average kW Discharged, Per Year
Fortress Power pays $180 per average kilowatt discharged — the highest customer payment rate of any participating manufacturer in the Efficiency Maine Small Battery Program. Payments are calculated based on your battery's average kW contribution across all dispatch events during the program year (April 1 through March 31). Events where you opt out count as zero toward your annual average. Payments are made annually after Efficiency Maine distributes performance funds to Program Partners.
Example Annual Earnings
| System | Avg. kW Discharged | Annual Payment |
|---|---|---|
| eForce 9.6 kWh | ~3 kW | ~$540/year |
| eForce 19.2 kWh | ~5 kW | ~$900/year |
| eBoost 32 kWh | ~7 kW | ~$1260/year |
Example scenarios only. Actual earnings vary based on battery size, configuration, and participation level. All Fortress Power products earn $180/kW — the highest rate in the program.
How to Participate
- Confirm you are a residential or small business customer on a Maine utility rate (CMP or Versant).
- Your system is installed with a qualifying Fortress Power battery, inverter, and Guardian device.
- After the installation is complete, enroll in the Efficiency Maine program. Your installer will work with you on enrolling, or you can enroll using the Fortress Power EnergyBroker program application.
- Efficiency Maine, Fortress Power and your utility provider will confirm your battery is operating correctly.
- Efficiency Maine pays Program Partners annually in June for power shared during the prior April 1 through March 31 program year. Fortress Power then issues payments to participating customers based on their individual contribution.
How the Program Works Once Your System is Installed
System Monitoring
The battery storage system needs to be installed in a location with an internet service so Fortress Power, Efficiency Maine and your utility provider can monitor your system. The Guardian Gateway or Dongle is required to program communications. You can see the same information using the Fortress Power Owner App.
Battery Dispatch
When Efficiency Maine calls an event, your battery automatically discharges to the grid, no action required from you. Events are typically called on weekdays between 5:00 PM and 9:00 PM and last 3 hours. There will be at least 2 events per month and no more than 60 events per year. You can opt out of any event, but opted-out events count as zero kW toward your annual average and will reduce your incentive payment.
Eligibility
- Must be interconnected to the grid per utility guidelines.
- Must be on a Maine utility Residential, Small General Service, or Small Commercial rate.
- May not use the battery system for any controls other than providing backup power for the customer’s premises.
- Have a reliable internet connection
- Own the following hardware:
Fortress Power Envy Inverters
Fortress Power eForce Batteries
Fortress Power eBoost Batteries
Fortress Power eFlex MAX Batteries
Fortress Power eVault MAX Batteries
Common Questions About the Efficiency Maine Small Battery Program
The Efficiency Maine Small Battery Program is a grid services initiative that pays Maine homeowners for sharing stored energy from their home battery during periods of peak electricity demand. Efficiency Maine — Maine's energy efficiency utility — funds Program Partners to dispatch residential batteries when the grid needs support. In return, participating homeowners earn an annual payment based on their battery's average kilowatt contribution across all dispatch events during the program year. The program runs year-round from April 1 through March 31, and the program term is 10 years.
Fortress Power customers earn $180 per average kilowatt discharged per year, the highest customer payment rate of any participating manufacturer in the program. Your annual payment is calculated based on your battery's average kW contribution across all dispatch events in the program year. Events where you opt out count as zero toward your annual average. As examples, a system averaging 3 kW of discharge earns approximately $540 per year, while a system averaging 5 kW earns approximately $900 per year. Actual earnings depend on your system size, configuration, and participation level.
When Efficiency Maine calls a peak event, your Fortress Power battery automatically discharges stored energy to the grid, no action is required from you. Events are typically called on weekdays between 5:00 PM and 9:00 PM, last 3 hours, and occur at least twice per month with a maximum of 60 events per year. You will receive advance notice of events from Fortress Power. You can opt out of any event at any time, though opted-out events count as zero kW toward your annual average payment.
All Fortress Power battery systems and inverters are eligible for the Efficiency Maine Small Battery Program. Your system must be interconnected to the grid per utility guidelines and must maintain a continuous internet connection so Fortress Power and Flip Energy can communicate with your battery during dispatch events. A Fortress Power Guardian Gateway or Guardian Dongle is required for program participation.
Yes. All Fortress Power battery systems require a solar PV installation to operate. Your solar panels charge your battery throughout the day, and Fortress Power draws on that stored energy during dispatch events. If you do not yet have solar, a certified Fortress Power installer can design and install a combined solar and battery system sized for your home and program participation goals.
Yes. You can opt out of any event at any time through the Fortress Power app or by responding to the Fortress Power event notification. Opting out does not remove you from the program, but the opted-out event will count as zero kilowatts toward your annual average, which will reduce your annual payment. The program is designed so your backup power is always prioritized. Efficiency Maine calls events well in advance and Fortress Power monitors your battery state of charge to protect your backup reserve.
Yes, partially. The Efficiency Maine Small Battery Program involves two program administration fees: Flip Energy (our program partner) retains a portion to cover program operations, and Fortress Power retains a small portion to cover monitoring and dispatch management. Your annual payment reflects the incentive after these fees. Contact our team for specific payment details based on your system configuration.
Complete the Fortress Power EnergyBroker enrollment form on this page. Our team will confirm your eligibility, connect you with a certified installer in Maine if needed, and handle enrollment through Flip Energy — Fortress Power's program partner for the Efficiency Maine Small Battery Program. Once your system is installed, interconnected, and your enrollment is confirmed, your battery will begin participating in dispatch events automatically.
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