How much roof space do you need for solar panels?
Each 400W solar panel needs roughly 1.7 square metres of roof, so a typical 5 kWp system of about 13 panels needs around 22 square metres of unshaded roof. Smaller 3 kWp systems need about 14 square metres, while larger 6 to 7 kWp systems need 26 to 31 square metres.
Roof space by system size
| System size | Panels (400W) | Roof area |
|---|---|---|
| 3 kWp | 8 panels | ~14 m² |
| 4 kWp | 10 panels | ~17 m² |
| 5 kWp | 13 panels | ~22 m² |
| 6 to 7 kWp | 15 to 18 panels | ~26 to 31 m² |
If your roof is small
If one roof face is too small, panels can be split across two faces (for example east and west), or you can fit a smaller system. Higher-efficiency panels squeeze more output from limited space. The SunSum calculator recommends a system size that suits typical roofs for your property type.
Frequently asked questions
- How big is a solar panel?
- A standard 400W panel is roughly 1.7 metres by 1.0 metre, so about 1.7 square metres each.
- Can panels go on more than one roof face?
- Yes. Splitting panels across two faces is common and a modern inverter handles different orientations well.
Related questions
Indicative estimates based on UK average data. Last updated 27 May 2026.