Solar Panel ROI Calculator

For a typical 4 kWp system costing around £7,000, the payback period in the UK is usually 8–12 years depending on your electricity usage, tariff rate, and how much sunlight your roof receives. South-facing roofs in southern England with high self-consumption (especially with battery storage) achieve payback fastest. Scotland and north-facing roofs will have longer payback periods due to lower generation.

The Smart Export Guarantee (SEG) is a UK government scheme that requires licensed energy suppliers to pay you for surplus electricity you export to the grid. Rates vary by supplier — typically 4–15p/kWh. To be eligible, your system must be installed by an MCS-certified installer and must have an export meter. You can compare current SEG rates at ofgem.gov.uk. Without battery storage, roughly 50% of your solar generation is typically exported.

Solar panel installation costs in the UK vary by system size: a 3 kWp system typically costs £5,000–£6,500; a 4 kWp system £6,000–£8,000; and a 6 kWp system £8,000–£11,000. Adding battery storage costs an additional £2,500–£5,000 for a 5–10 kWh battery. Prices have fallen significantly in recent years. Always get at least 3 quotes from MCS-certified installers and check the Trustmark register.

In the UK, a solar panel system generates approximately 800–1,000 kWh per year per kWp of installed capacity. The average across the UK is around 900 kWh/kWp/year. South England and coastal areas typically achieve 950–1,000 kWh/kWp/year, while Scotland achieves 800–850 kWh/kWp/year. A 4 kWp system therefore generates roughly 3,200–4,000 kWh annually — covering 80–100% of an average UK household's electricity needs.

Battery storage increases your solar self-consumption from around 50% to 70–80%, meaning you use more of the electricity you generate rather than exporting it at a low SEG rate. At current UK electricity prices (~28p/kWh to buy vs ~5p/kWh to export), using an extra unit yourself saves about 23p more than exporting it. A 5–10 kWh battery typically adds £2,500–£5,000 to your installation cost and may extend payback by 2–4 years, but significantly boosts your 25-year return.

Yes — UK studies suggest solar panels increase property values by 0.5–2%, and properties with solar panels sell faster. The Value Added Tax (VAT) on residential solar installations is 0% (as of April 2022). Solar panels are generally considered a permitted development and don't require planning permission unless your home is listed or in a conservation area. They can also reduce your EPC rating, which is increasingly important for mortgage lending.