How UK solar costs are calculated
System size × cost per watt, in £. The calculator uses £1.50 per watt as a typical UK installed figure. A 4 kW system costs about £6,000; a 4.8 kW system about £7,200. Typical UK prices for a 4 kW system run about £5,000 to £8,000 installed, depending on roof access, scaffolding and the installer.
The split is roughly 60% equipment (panels, inverter, mounting, wiring) and 40% labour, permits and certification. Batteries, bird-proofing and consumer-unit upgrades are usually extra — add them as fixed costs.
Always use an MCS-certified installer in the UK: certification is required for Smart Export Guarantee payments, and it is your main quality protection. Get three local quotes before you sign.
Size your system first with the UK solar panel calculator, or see the full return with the ROI calculator.