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Assess your energy usage
How many panels you need depends on how much electricity you use, where you live, and which way your roof faces. Fill in the three fields below and we carry those numbers through the rest of the guide.
Where to find your annual kWh
The most accurate source is your electricity bill or smart meter app — look for “annual consumption” or “yearly usage.” UK average is around 3,500 kWh per year for a 3-bed home, but ranges from under 2,000 kWh for a small flat to over 6,000 kWh for a large family home with electric heating.
Why postcode matters
Solar irradiance varies significantly across the UK. Cornwall gets roughly 30% more peak sun hours per year than northern Scotland. We use your postcode prefix to look up your region's average — it never leaves your browser.
Roof orientation
South-facing is ideal. South-east or south-west loses about 6% annually compared to due south — usually not enough to change the panel count. East or west loses around 15%. Pure north is the only direction where the economics become genuinely tight.