Quick answer
A typical UK parish church installation uses 15–30 solar panels (8–17 kW), generating roughly 7,000–15,000 kWh per year. Larger parish churches with active halls use 30–55 panels (17–30 kW). Cathedrals use 60–370 panels (30–200 kW) depending on which buildings of the cathedral close are included.
Full answer
Panel count is determined by three factors: (1) annual electricity demand of the parish, (2) available unshaded south-facing roof area, and (3) electrical supply rating (single-phase 13 kW limit vs three-phase). Most parish churches are constrained by available roof area on suitable slopes rather than by demand.
Modern panels are typically 400–440 watts each. A 15 kW system uses approximately 33–38 panels covering 70–85 m² of roof area. A 30 kW system uses approximately 65–75 panels covering 140–170 m². For comparison: most parish churches have 100–300 m² of usable south-facing roof on the chancel, nave south slope, and outbuildings combined.
Sunday-only parish churches typically size systems to offset 50–60% of annual electricity demand. Active parish hall buildings can size to offset 80–100% because higher self-consumption makes the additional capacity economically viable. Combined church+hall sites often deliver the strongest economics.
We recommend sizing conservatively for the first phase and expanding later if demand or grants support it. A 15 kW system installed in Year 1 can be expanded to 25 kW in Year 3 if the parish hall demand justifies it.
Related questions
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