Start here if you are planning a rooftop system. These tools turn your electricity use, your roof and your location into a system size and a realistic yearly output.
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Sizing a solar system comes down to three numbers: how much electricity you use in a year, how much each kWp of panels produces where you live, and how many panels physically fit on your roof. Each calculator in this hub handles one of those steps and links to the next.
If you already have panels, use the kWh per kWp calculator with your generation meter reading to check whether the system performs as it should.
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Solar Panel Output in Winter: UK Data, Sun Angles and Tips
Measured UK winter solar output, sun height and day length by city, best winter tilt and snow safety.
Frequently Asked Questions
How many solar panels does a typical UK home need?
The Energy Saving Trust describes a typical UK home system as about 4.5 kWp, which is around 12 panels. Your own figure depends on your yearly kWh use, roof direction and how much of your demand you want to cover, so use the solar panel calculator with your bill.
How much does 1 kWp of solar produce in the UK?
UK measured data for domestic systems shows a median of roughly 800 kWh per kWp a year, with sunnier southern regions doing better than the north. Direction, tilt and shading move this figure up or down by a large margin.
What size solar system do I need for my bill?
Convert your bill to kWh by dividing the energy part by your unit rate, then divide the yearly kWh by your local kWh per kWp. The electricity bill to solar size calculator does both steps and removes the standing charge first.
Checked October 2026 by the Solaxyra Editorial Team. Read how we build and check our tools in our editorial policy.