Madison ESS
Madison ESS is a 5 MW battery storage project in Somerset County, Maine, operated by Agilitas Energy, Inc.. EIA-860M lists 1 generating unit here, inside ISO New England. Its unit entered service in 2019.
As of 2026-07 (inventory dated 2026-07-31) · EIA-860M Preliminary Monthly Electric Generator Inventory · eia.gov/…/july_generator2026.xlsx · eia.gov/…/eia860m
- Nameplate capacity
- 4.9 MW
- 4.9 MW net summer
- Generating units
- 1
- In service
- 2019
- EIA plant ID
- 64765
Where it is
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- County
- Somerset County, Maine
- Coordinates
- 44.793, -69.876
- Balancing authority
- ISNE
- Sector
- IPP Non-CHP
Units, technology and status
- Operator of record
- Agilitas Energy, Inc.
- Primary energy source
- Battery
- Technologies
- Batteries
- Status
- Operating
Madison ESS: FAQ
- Where is Madison ESS?
- In Somerset County, Maine (ME). The map on this page is placed at the coordinates EIA files for the plant, which locate the site rather than any individual unit.
- How big is Madison ESS?
- 5 MW of nameplate capacity across 1 unit, as of the EIA-860M release for 2026-07.
- Who owns Madison ESS?
- EIA-860M names Agilitas Energy, Inc. as the reporting entity. That is the operator of record on the survey, which is not always the ultimate owner.
- Is this the same as Madison ESS LLC?
- Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Agilitas Energy, Inc. here — not the project company that holds the asset. Project companies are commonly registered as an LLC carrying the plant's name, so a search for "Madison ESS LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
- Is Madison ESS still running?
- EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.