Graniterock Quarry
San Benito County, California · EIA plant ID 65485 · Operator: CalCom Energy
Nameplate4MWSummer 4 MW
Generators1in service
Net generation9GWh12 mo to Dec 2025
Capacity factor23%solar units, summer MW
Heat rate—thermal plants only
First online2022
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) |
|---|---|---|---|
| 2022 | 2.5 | 19.7% | — |
| 2023 | 9.1 | 23.5% | — |
| 2024 | 8.9 | 23.1% | — |
| 2025 | 8.8 | 22.8% | — |
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 |
|---|---|---|---|---|---|---|---|---|
| GRWQ | Solar Photovoltaic | PV | 4.4 | 4.4 | Sep 2022 | Operating | — | coming soon |
Owner / operator
Operator: CalCom Energy. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Granite Rock Company | 100.0% | 4 MW |
Nearby plants
Within 80 km.
| Gavilan Community College Solar Project | 2 MW | 14 km |
| Hollister Wastewater Facility | 1 MW | 14.2 km |
| Gilroy Peaking Energy Center | 144 MW | 14.7 km |
| Gilroy Power Plant | 130 MW | 14.8 km |
| Hollister Solar LLC | 2 MW | 15.6 km |
| Elkhorn Battery Energy Storage System | 183 MW | 17.7 km |