Where is Mount Saint Mary's?

In Frederick County, Maryland (MD). 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 Mount Saint Mary's?

14 MW of nameplate capacity across 1 unit, as of the EIA-860M release for 2026-07.

Who owns Mount Saint Mary's?

EIA-860M names Constellation Solar Horizons 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 Mount Saint Mary's LLC?

Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Constellation Solar Horizons 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 "Mount Saint Mary's LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.

Is Mount Saint Mary's still running?

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

Mount Saint Mary's

Mount Saint Mary's is a 14 MW solar farm in Frederick County, Maryland, operated by Constellation Solar Horizons LLC. EIA-860M lists 1 generating unit here, inside PJM. Its unit entered service in 2012.

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: 13.7 MW; 13.7 MW net summer
Generating units: 1
In service: 2012
EIA plant ID: 57758

Where it is

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County: Frederick County, Maryland
Coordinates: 39.675, -77.345
Balancing authority: PJM
Sector: IPP Non-CHP

Units, technology and status

Operator of record: Constellation Solar Horizons LLC
Primary energy source: Solar
Technologies: Solar Photovoltaic
Status: Operating

Every plant Constellation Solar Horizons LLC reports to EIA →

Mount Saint Mary's: FAQ

Where is Mount Saint Mary's?: In Frederick County, Maryland (MD). 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 Mount Saint Mary's?: 14 MW of nameplate capacity across 1 unit, as of the EIA-860M release for 2026-07.
Who owns Mount Saint Mary's?: EIA-860M names Constellation Solar Horizons 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 Mount Saint Mary's LLC?: Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Constellation Solar Horizons 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 "Mount Saint Mary's LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
Is Mount Saint Mary's still running?: EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.