Mount Saint Mary's
Frederick County, Maryland · EIA plant ID 57758 · Operator: Constellation Solar Horizons LLC
Nameplate14MWSummer 14 MW
Generators1in service
Net generation17GWh12 mo to Aug 2026
Capacity factor14%solar units, summer MW
Heat rate—thermal plants only
First online2012
The 12-month figures include preliminary EIA-923 months, which EIA revises. Final data runs through Dec 2025.
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), solar units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2012 | 11.6 | 19.2% | — |
| 2013 | 23.6 | 19.7% | — |
| 2014 | 23.2 | 19.3% | — |
| 2015 | 23.2 | 19.3% | — |
| 2016 | 21.8 | 18.1% | — |
| 2017 | 20.9 | 17.4% | — |
| 2018 | 19.6 | 16.4% | — |
| 2019 | 20.1 | 16.7% | — |
| 2020 | 20.7 | 17.2% | — |
| 2021 | 19.9 | 16.6% | — |
| 2022 | 19.5 | 16.2% | — |
| 2023 | 17.8 | 14.8% | — |
| 2024 | 17.9 | 14.8% | — |
| 2025 | 16.4 | 13.7% | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| PV1 | Solar Photovoltaic | PV | 13.7 | 13.7 | Jul 2012 | Operating | — | coming soon |
Owner / operator
Operator: Constellation Solar Horizons LLC. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Constellation Solar Horizons LLC | 100.0% | 14 MW |
Nearby plants
Within 80 km.
| Emmitsburg Solar Arrays | 2 MW | 3.3 km |
| Baker Point | 9 MW | 11.7 km |
| LeGore Bridge Solar Center | 20 MW | 11.8 km |
| FR_Williamsport LLC | 20 MW | 13 km |
| Cannonball Solar (CSG) | 2 MW | 15.6 km |
| Union Bridge Solar | 8 MW | 18.6 km |