What size solar system do I need?
Short answer
Most UK homes fit 3.5 to 6 kWp, about 8 to 15 modern panels. Size to roof, budget and future use, not just current bills: panels are cheap relative to scaffold, so fill good roof space if you plan an EV or heat pump. Above about 3.68 kW on single phase, the network operator must approve the connection first.
Last checked 24 September 2026 · 1 source
In more detail
- EST average ~4.5 kWp, ~12 panels, 20-30 m2.
- Modern panels 430-480 W, so 12 panels ~5.5 kWp.
- DC oversizing onto a smaller inverter (e.g. 1.2-1.3:1) is common; some clipping on peak days is expected.
The facts, dated
- 01Average domestic system ~4.5 kWp, ~12 panels, 20-30 m2 roof (EST) — 4.5 kWp
market_data · UK · checked 24 September 2026 · Energy Saving Trust
What we saw in the field
[QA review 2026-09-24] I-8 AGREES (proxy: MCS listing-name median 330 W 2019 -> 480 W 2023). | Earlier notes: Installer claim panels went from 300-350 W to 450-480 W in ~5 years is consistent with current datasheets (e.g. JA/Jinko 430-480 W residential ranges) - not independently dated here.
Sources
- Energy Saving Trust — energysavingtrust.org.uk/advice/solar-panels/
Last checked: 24 September 2026