Are solar panels worth it in the UK in 2026? The real numbers

A 4 kW system — the standard UK domestic size, 8 to 14 panels on 13 to 22 m² of roof — costs roughly £6,600 to £8,500 installed in 2026, with 0% VAT on domestic solar and battery installations. It generates around 3,400 kWh a year in southern England, dropping to about 85-90% of that in northern England and 80-85% in Scotland and Northern Ireland.

As a planning rule, budget around 850 kWh per kWp installed per year for a decent, unshaded, roughly south-facing roof. East or west-facing typically loses 10-20%, and shading from a chimney or tree costs more than people expect because it drags down whole strings of panels.

Roughly 70% of the year's output lands between April and September — the opposite of when your heating and lighting demand peaks.

Under the Ofgem price cap for 1 October to 31 December 2026, electricity is 26.32p per kWh with a 54.83p daily standing charge. Every unit you use as it is generated saves you that full 26.32p.

Units you export earn the Smart Export Guarantee rate from a supplier instead. Published SEG rates in 2026 span roughly 3p to 25p per kWh depending on supplier and tariff, with many mainstream offers in the low teens — well below the import price. So a unit self-used is typically worth about twice a unit exported.

Without a battery, most households self-consume something like a third to a half of what they generate. Timing the dishwasher, washing machine and hot water for the middle of the day costs nothing and pushes that share up.

Independent 2026 estimates for a 4 kW system put annual savings around £336 from self-consumption plus roughly £300 of export income, giving payback in the region of 11 to 13 years against a 25-year panel warranty. Your own figure depends heavily on system cost, usage pattern and SEG rate, which is exactly what the payback calculator works out.

A battery adds £3,000 to £8,000 and lifts self-consumption a lot, but it usually lengthens simple payback unless you pair it with a time-of-use tariff and charge overnight at a cheap rate. Match battery size to generation, not to ambition — a 13 kWh battery on a 4 kW array rarely gets fully cycled.

You are not obliged to take SEG from the company that installed the panels or the one that sells you power, so compare export rates separately. Use MCS-certified installers — MCS certification is required for SEG registration and 0% VAT — and get at least three quotes, because prices for identical systems vary by thousands.