How we calculated

A typical home solar panel system is worth around £605 to £675 a year with an ideal south-facing roof, and around £410 to £470 a year with an east-facing or partly shaded roof. Those figures combine electricity bill savings and Smart Export Guarantee payments, at June 2025 prices.

How the calculation works

There is no single official figure for what solar panels save a UK household, so we show the full working:

1. The figures come from Which?'s solar payback modelling, the only published source that splits the benefit into bill savings and export payments. It models a 4.6 kWp system (around 10 panels) costing £7,400, with occupants at home during the day, an electricity price of 25.8p per kWh and an export rate of 12p per kWh, at prices as of 1 June 2025.

2. Ideal scenario, a south-facing roof at 35 degrees with no shading: bill savings of £270 to £285 a year plus export payments of £335 to £390 a year, giving £605 (Edinburgh) to £675 (Cardiff) in total.

3. Compromised scenario, an east-facing roof with modest shading: £410 to £470 a year in total across the same four locations.

4. Cross-checks: the government's clean-energy campaign states households save on average over £500 a year with solar panels, and the Energy Saving Trust puts the average installation at around £7,600 for a 4.5 kWp system with a typical export rate of around 12p per kWh. Both sit consistently with the Which? modelling.

5. Payback: on the Energy Saving Trust's July 2026 figures, an ideal-case system pays back in 9 to 12 years depending on location and occupancy. Which?'s modelling puts a compromised roof at roughly 15 to 18 years.

Caveats

• Roof orientation and shading move the result more than location does: around £200 a year of difference, versus around £70 between the best and worst UK locations.

• Being out all day lowers the total: you export more at 12p instead of avoiding imports at 25.8p. The modelled household is home during the day.

• Prices are dated June 2025 for the benefit figures and July 2026 for payback. Electricity prices change quarterly with the Ofgem price cap, and the benefit moves with them.

• Smart Export Guarantee rates are set by each supplier and vary widely; they must be above zero, but choosing a good export tariff is part of the return.

• The payback range of 9 to 12 years is an ideal-case band, not a promise; a compromised roof can take 15 to 18 years.

• VAT on supply-and-install of residential solar is zero-rated until 31 March 2027, then reverts to 5%. Supply-only purchases are standard-rated.

• The modelling assumes no battery. A battery changes both the cost and the self-consumption share, so quotes with storage need their own comparison.

Sources

• Which?: Are solar panels worth it? (benefit modelling, prices at 1 June 2025)

• Energy Saving Trust: Solar panels (installation cost, payback table on July 2026 fuel prices, typical export rate)

• Ofgem: Smart Export Guarantee for electricity suppliers (which suppliers must offer tariffs; rates above zero)

• GOV.UK: Solar panels (clean energy campaign) (average savings of over £500 a year)

• HMRC: VAT on energy-saving materials, Notice 708/6 (zero rate to 31 March 2027)

Last updated: 31 August 2026. Next planned update: quarterly, alongside Ofgem price-cap changes; the VAT treatment changes on 1 April 2027.