In Berkshire County, Massachusetts (MA). 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 401 South?

2 MW of nameplate capacity across 2 units, as of the EIA-860M release for 2026-07.

EIA-860M names Madison Energy Investments LLC 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 401 South LLC?

Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Madison Energy Investments LLC 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 "401 South LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.

Is 401 South still running?

EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.

401 South

401 South is a 2 MW battery storage project in Berkshire County, Massachusetts, operated by Madison Energy Investments LLC. EIA-860M lists 2 generating units here. Its units entered service in 2023.

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: 1.5 MW; 1.5 MW net summer
Generating units: 2
In service: 2023
EIA plant ID: 67241

Where it is

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County: Berkshire County, Massachusetts
Coordinates: 42.464, -73.184
Balancing authority: SOCO
Sector: IPP Non-CHP

Units, technology and status

Operator of record: Madison Energy Investments LLC
Primary energy source: Battery
Technologies: Batteries, Solar Photovoltaic
Status: Operating

This site runs on more than one energy source. EIA-860M capacity splits: Battery 1 MW, Solar 1 MW. It is filed here under Battery, the source with the most capacity.

Every plant Madison Energy Investments LLC reports to EIA →

401 South: FAQ

Where is 401 South?: In Berkshire County, Massachusetts (MA). 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 401 South?: 2 MW of nameplate capacity across 2 units, as of the EIA-860M release for 2026-07.
Who owns 401 South?: EIA-860M names Madison Energy Investments LLC 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 401 South LLC?: Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Madison Energy Investments LLC 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 "401 South LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
Is 401 South still running?: EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.