How many solar panels do I need?
Most UK homes need between 8 and 18 solar panels, which is a 3 to 7 kWp system using modern 400W panels. A 3-bedroom home typically needs about 10 panels (4 kWp) and a 4 or 5-bedroom home around 13 to 18 panels (5 to 7 kWp). The right number depends on your annual electricity use and how much roof space you have.
Sizing a solar system starts with how much electricity you use in a year. Each kWp of panels generates roughly 850 kWh a year in the UK, adjusted for your region, roof direction and shading.
Panels needed by home size
| Home | Annual use | System | Panels (400W) |
|---|---|---|---|
| 1 to 2-bed flat or terrace | ~2,000 to 3,000 kWh | 3 kWp | 8 panels |
| 3-bed semi | ~3,500 kWh | 4 kWp | 10 panels |
| 4-bed detached | ~4,500 kWh | 5 kWp | 13 panels |
| 5-bed or EV household | ~6,000 kWh+ | 6 to 7 kWp | 15 to 18 panels |
How to size from your electricity usage
Find your annual usage in kWh on your electricity bill or annual statement. As a rough guide, divide your annual usage by about 850 to get the kWp you could justify, then check it fits your roof. For example, 4,500 kWh divided by 850 is around 5 kWp.
If you have an electric vehicle or a heat pump, add headroom: an EV alone can add 2,000 to 3,500 kWh a year to your usage.
Will it fit your roof?
Each 400W panel needs roughly 1.7 square metres. A 5 kWp system of 13 panels needs about 22 square metres of unshaded roof. South-facing pitches are ideal, but east and west roofs work well and can be split across two faces.
Get your exact number
The SunSum calculator recommends a system size and panel count for your home from your postcode, property type and bill, in under a minute.
Frequently asked questions
- How many solar panels to power a house?
- A typical UK house is well served by 10 to 13 panels (4 to 5 kWp). Larger or higher-usage homes need 15 to 18 panels.
- How many panels do I need for an EV?
- An electric vehicle can add 2,000 to 3,500 kWh to annual usage, so most EV households size up to 6 to 7 kWp (15 to 18 panels), ideally with a battery.
Related questions
Indicative estimates based on UK average data. Last updated 26 May 2026.