How much electricity do solar panels produce?
A single 400W solar panel produces around 340 kWh of electricity a year in the UK, and a typical 5 kWp system of about 13 panels produces roughly 4,000 kWh a year. Output is based on the UK average of around 850 kWh per kWp installed, adjusted up or down for your region, roof direction and any shading.
Typical annual output by system size
| System size | Panels (400W) | Annual output |
|---|---|---|
| 3 kWp | 8 panels | ~2,550 kWh |
| 4 kWp | 10 panels | ~3,400 kWh |
| 5 kWp | 13 panels | ~4,250 kWh |
| 6 kWp | 15 panels | ~5,100 kWh |
What changes the output
- Roof direction: south is best; east or west generate about 85% as much.
- Region: the North generates around 93% of the UK average, the South a little above.
- Shading from trees, chimneys or buildings reduces output.
- Roof pitch: around 30 to 40 degrees is close to ideal.
Frequently asked questions
- How much does one solar panel produce per day?
- On average around 0.9 kWh a day across the year, more in summer and less in winter.
- Will solar cover my whole electricity bill?
- It can cover a large share, especially with a battery, but most homes still draw some grid power, particularly in winter.
Related questions
Indicative estimates based on UK average data. Last updated 27 May 2026.