What Affects Solar Output?
Find the right system size for your roof
Panel count depends on your electricity use, roof space and direction — not on a rule of thumb. Get a recommended size and what it should cost.
Size My SystemFree calculator. No contact details required to see your result.
Find the right system size for your roof
Panel count depends on your electricity use, roof space and direction — not on a rule of thumb. Get a recommended size and what it should cost.
Size My SystemWhat affects how much solar panels produce?
8 factors affect UK solar output (ranked by impact): (1) Roof direction: south=100%, east/west=80-85%, north=55-60% (15-45% impact). (2) Shading: partial shade reduces 10-30% (10-30% impact). (3) Location: south England vs Scotland = ±15% (10-15% impact). (4) Tilt angle: optimal 35°, flat roof = 87% (2-15% impact). (5) Soiling: dirt/droppings reduce 2-5% (2-5% impact). (6) Inverter efficiency: 96-98% conversion (2-4% impact). (7) Temperature: panels lose 0.4%/°C above 25°C (1-3% impact in UK). (8) Degradation: 0.3-0.5% per year (cumulative). Direction and shading are the big two — everything else is minor.
Frequently Asked Questions
Related: Home Heating Systems
Solar panels are most powerful when combined with an efficient heating system. Heat pumps use solar-generated electricity to heat your home at 300-400% efficiency — making them the ideal partner for solar.
A heat pump converts 1kWh of electricity into 3-4kWh of heat.
From our sister site Home Heat Pump Guide
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Find the right system size for your roof
Panel count depends on your electricity use, roof space and direction — not on a rule of thumb. Get a recommended size and what it should cost.
Size My SystemFree calculator. No contact details required to see your result.