This solar panel payback calculator shows how many years it takes for a UK solar panel system to pay for itself. Enter your system size, installation cost, electricity rate and how much solar power you use yourself to see your annual savings, export income and payback period.
Savings, export income & ROI
A solar panel system saves money in two ways: by reducing the electricity you buy from the grid (the self-consumption saving) and by earning income for surplus electricity exported to the grid under the Smart Export Guarantee (SEG). The payback period is simply the installation cost divided by the combined annual benefit.
The higher your electricity rate and the more solar output you use yourself, the faster the system pays for itself. Self-consumption is typically around 30% to 50% without a battery, rising to 60% to 80% with battery storage. Using appliances during daylight (running dishwashers, washing machines and EV chargers during the day) pushes self-consumption higher without needing a battery.
In the UK, solar panels produce approximately 850 to 1,000 kWh per kWp per year. The average across the country is about 900 kWh/kWp. Southern England performs better (nearer 1,000 kWh/kWp) while Scotland averages closer to 800 kWh/kWp. A south-facing roof at a 30-35 degree pitch is ideal, but east-west systems still perform well — typically 85% to 90% of a south-facing setup.
| System size | Typical annual generation | Typical installed cost |
|---|---|---|
| 3 kWp (10 panels) | ~2,700 kWh | £5,000 – £6,500 |
| 4 kWp (13 panels) | ~3,600 kWh | £6,000 – £8,000 |
| 6 kWp (19 panels) | ~5,400 kWh | £7,500 – £10,000 |
Costs are 0% VAT (zero-rated for residential installations until at least March 2027). Prices vary by installer and panel brand — always get at least three quotes.
The SEG requires large suppliers to pay you for electricity you export to the grid. Rates vary by supplier and tariff type — fixed-rate SEG tariffs typically offer 3p to 8p per kWh, while time-of-use or "agile" export tariffs can pay 10p to 15p per kWh at peak times. You need a smart meter to claim SEG payments.
System: 4 kWp, installed for £7,000 (0% VAT)
Generation: 4 x 900 = 3,600 kWh/year
Self-consumption (50%): 1,800 kWh x 26.11p = £469.98/year saved
Export (50%): 1,800 kWh x 7p = £126.00/year earned
Total annual benefit: £595.98
Payback: £7,000 / £595.98 = ~11.7 years
Over 25 years (typical panel warranty), total return = £595.98 x 25 = £14,900 — a return of 113% on the investment.
Increase self-consumption. Every kWh you use yourself saves you 26p (the buy rate), whereas exporting it earns only 3p to 15p. Set timers on your dishwasher, washing machine and EV charger to run during peak solar hours (10am to 3pm).
Consider a battery. A home battery (4-13 kWh capacity) stores surplus daytime generation for evening use. It adds £2,000 to £5,000 to the upfront cost but pushes self-consumption from ~50% to 70-80%, accelerating savings in the long run.
Check your EPC. Installing solar panels can improve your EPC rating by one to two bands, which may increase your property value and is relevant if you are a landlord needing to meet the minimum EPC E standard for rental properties.
Compare the cost of heating your home with the energy bill calculator using current Ofgem cap rates. The EV charging cost calculator shows how cheap solar electricity makes EV charging, and the savings goal calculator helps you save towards the installation cost.
A typical 4kWp residential system costing around £6,000 to £8,000 generates roughly 3,400 to 3,800 kWh per year. With self-consumption of about 50% and export payments under the Smart Export Guarantee, the annual saving is typically £600 to £900. This gives a payback period of roughly 8 to 12 years depending on your electricity rate and how much you use during daylight hours.
UK solar panels generate approximately 850 to 1,000 kWh per kWp per year, depending on location, roof orientation and shading. A south-facing roof in southern England performs best at around 1,000 kWh per kWp. A 4kWp system in an average location produces roughly 3,600 kWh per year.
The Smart Export Guarantee (SEG) requires licensed electricity suppliers with over 150,000 customers to offer a tariff for exported solar electricity. Rates vary by supplier and are typically between 3p and 15p per kWh. You need a smart meter or an export meter to claim. The SEG replaced the old Feed-in Tariff which closed to new applicants in 2019.
Residential solar panel installations have been zero-rated for VAT since April 2022, and this is confirmed until at least March 2027. This means you pay no VAT on the supply and installation of solar panels on your home, which saves 20% compared to the standard rate.
Research suggests solar panels can add 1% to 3% to a property's value, depending on the system size, age, and local market. A well-maintained system with a good EPC rating improvement can be a selling point. However, leased solar panel arrangements can complicate sales because the buyer must take over the lease.
Installed costs vary widely by system size, panel quality and installer. As a rough guide, a 3kWp system costs £5,000 to £6,500, a 4kWp system £6,000 to £8,000, and a 6kWp system £7,500 to £10,000. Battery storage adds £2,000 to £5,000. Prices have fallen over the past decade but installer labour costs have risen. Get at least three quotes.
Yes, but output is significantly reduced. Solar panels generate electricity from daylight, not direct sunshine. In winter months (November to January) a UK system produces roughly 10% to 15% of its annual output. On an overcast summer day it still generates 20% to 40% of its peak capacity. The annual average accounts for all weather conditions.
A battery stores excess daytime generation for evening use, increasing self-consumption from roughly 50% to 70% or 80%. At current prices of £2,000 to £5,000, a battery extends the payback period by 2 to 4 years but provides greater energy independence and higher long-term savings, especially if you are on a time-of-use tariff.
