The sun shines 34% more on Plymouth than on Edinburgh. That single fact, buried in a new analysis by YourWeather, explains why a solar panel system pays for itself in 9 years in the Devon city but takes 15 in the Scottish capital. For any homeowner weighing the upfront cost, typically £5,000 to £8,000 for a 3.5 kW system, geography is destiny.
The analysis, as reported by yourweather.co.uk, calculated payback using local solar irradiance data, typical system costs, and the Smart Export Guarantee (SEG) rates. It did not factor in the 0% VAT on installations, a relief introduced in 2023 that knocks £500 off a £6,000 system, or the possibility of battery storage. Even so, the gap between best and worst is stark.
Who qualifies, and who doesn’t
Location is only one variable. Your roof orientation, shading, and electricity consumption matter just as much. A south-facing roof in Manchester without nearby trees will outperform a north-facing one in Brighton. The Energy Saving Trust estimates a typical London home saves £270 a year on bills, but only if it uses 50% of the power generated. Export the rest at the SEG rate, currently 5p to 15p per kWh depending on supplier, and the annual saving drops to around £200.
The government’s Boiler Upgrade Scheme and Home Upgrade Grant do not cover solar panels directly, but solar can improve your EPC rating by up to two bands. That matters for resale value and for meeting the Minimum Energy Efficiency Standards due to tighten in 2028. Landlords should note: installing solar on a rental property currently yields a payback of 7–10 years because of the higher daytime energy use by tenants.
What it costs a typical 3-bed semi
Ofgem data shows the average household using 12,000 kWh of gas and 2,900 kWh of electricity per year. A 3.5 kW solar system covering 60% of that electricity need would save roughly £300 annually at current price cap rates (24.5p per kWh). Add the SEG payments for the 1,500 kWh exported at 10p, another £150, and total annual benefit reaches £450. Divide the typical installed cost of £6,000 and you get a 13-year payback. That is the UK average. Plymouth’s 9 years comes from 1,100 hours of sunshine versus Edinburgh’s 750.
The catch is that SEG rates are not guaranteed. Octopus Energy pays 15p per kWh; British Gas pays 5p. The difference adds £150 a year to the export income. Homeowners who lock in a higher SEG tariff effectively shorten their payback by two years without spending a penny more on hardware.
Battery storage changes the maths
A 5 kWh battery adds roughly £2,000 to the upfront cost but lifts self-consumption from 50% to 80%. That means you buy less electricity from the grid at 24.5p and export less at 10p. The net effect is a payback period roughly equal to solar alone, about 13 years, because the battery saves more per kWh than you earn by exporting. But if time-of-use tariffs like Octopus Flux become widespread, batteries will let you arbitrage: charge at cheap night rates and use power during the peak 4pm–7pm window. That could cut payback to 9–10 years.
Ofgem is consulting on a new ‘smart export guarantee’ framework that would require suppliers to offer a minimum rate indexed to wholesale prices. If that happens, payback periods in cloudy cities like Edinburgh could shrink by two to three years. The consultation closes in October 2024.
Frequently Asked Questions
No, the YourWeather analysis used solar-only costs. Adding a battery typically increases upfront expense by £2,000 but can reduce payback by improving self-consumption, especially with time-of-use tariffs.
The Boiler Upgrade Scheme does not cover solar, but the Home Upgrade Grant (for low-income households) and ECO4 (for energy efficiency) may include solar in some cases. Check eligibility on gov.uk.
