How big a solar system do I need?
Solar sizing is a balance between roof space, your annual electricity use, and whether you have an EV. The tool below recommends a kWp target based on the only three numbers that matter.
Frequently asked questions
What's the average UK solar system size?
The most-installed size is 4kWp (around 9–10 panels). That covers ~80% of a typical 4-bed home's electricity over a year, less in winter.
Should I oversize for an EV?
Yes if you have the roof. Adding 1–2kWp to cover EV charging usually pays back faster per panel than the original system because of the high marginal value.
Will I generate more than I use?
In summer, yes — a 4kWp system on a sunny day produces 25–30kWh, more than most homes use. The export tariff or a battery captures the surplus.