How to Use the Solar Panel ROI Calculator
Enter your system size in kilowatt-peak (kWp) and the installation cost. The annual generation figure is automatically estimated at 950 kWh per kWp — a reasonable UK average — but you can override this with a figure from your installer's quote or a solar irradiance tool. Adjust the self-consumption percentage to reflect how much of your generated electricity you actually use at home versus exporting.
The calculator uses your electricity unit rate and Smart Export Guarantee (SEG) export rate to compute your annual savings and export income. It then calculates the simple payback period, the 25-year return on investment, and the net present value using a 3% real discount rate to account for inflation.
Frequently Asked Questions
How much do solar panels save in the UK in 2026?
In 2026, a typical 4 kWp solar panel system in the UK saves between £600 and £1,000 per year, depending on your energy usage, self-consumption rate, and electricity unit rate. With the Smart Export Guarantee (SEG), you also earn income for surplus electricity exported to the grid.
What is the SEG export tariff?
The Smart Export Guarantee (SEG) is a government-backed scheme requiring licensed electricity suppliers with 150,000+ customers to offer a tariff for surplus solar energy exported to the grid. Rates vary by supplier but typically range from 3p to 15p per kWh in 2026.
How long do solar panels take to pay back in the UK?
The typical payback period for solar panels in the UK is 8 to 12 years in 2026, depending on system size, installation cost, energy usage, and SEG export income. Higher self-consumption and good SEG rates can shorten the payback period significantly.
Do solar panels add value to a property in the UK?
Yes, research suggests solar panels can increase a UK property's value by 1–4%, particularly as energy efficiency becomes more important to buyers. A higher EPC rating resulting from solar installation can also make a property more attractive on the market.
Are there solar panel grants available in the UK in 2026?
In 2026, solar panels are zero-rated for VAT (0%), which represents a significant saving. Low-income households may also be eligible for grants through the ECO4 scheme or the Great British Insulation Scheme. The previous SEG Feed-in Tariff closed to new applicants, but existing recipients continue to receive payments.