Solar Panel ROI Calculator – UK 2026
A 7 kWp system without a battery pays back in the UK in 5.39 years: the annual saving is £1,261, self-generated electricity costs £0.04/kWh (85% cheaper than the £0.26/kWh grid price), and over the 25-year system lifetime you save £37,870. Enter your own solar system's parameters or use the simple wizard to find out the annual savings, payback period and electricity production in the UK.
Basic
Rough conversion of your bill to annual consumption using the average electricity price — estimate only.
Recommended size for your consumption: 7 kWp.
Estimate based on an average price of ~£930/kWp (materials, installation, VAT) — the actual price depends on the installer, roof and chosen components.
Your result
5.39 years
Payback period
Calculated for system: 7 kWp · no battery
Annual savings
£1,261
Monthly bill before → Monthly bill after
£130 → £72
Cost of your own kWh
£0.04
grid price: £0.26
Lifetime savings
£37,870
What this means: Your own electricity works out at £0.04/kWh, which is 85% cheaper than the grid price of £0.26/kWh. The system covers roughly 45% of your annual electricity use; you'll still buy the rest from the grid.
| Setup 1 | |
|---|---|
| Calculated for system | 7 kWp · no battery |
| System cost | £7,000 |
| Payback period | 5.39 years |
| Annual savings | £1,261 |
| Lifetime savings | £37,870 |
| Annual production | 7000 kWh |
| CO₂ saved | 1.23 t/year |
| Self-consumption | 38.57 % |
| Annual electricity consumption | 6000 kWh |
Setup 1
- Self-consumption: 2700 kWh (39 %)
- Exported to grid: 4300 kWh (61 %)
This calculation is indicative and is based on the entered inputs and average values for the UK (specific yield, electricity prices, a representative Smart Export Guarantee rate rather than an exact supplier tariff). Actual production and savings depend on the specific roof, orientation, shading and installer. It does not replace a quote from a solar installer.
How solar panel ROI is calculated
Annual production is calculated as the installed capacity (kWp) multiplied by the specific yield (kWh produced per year per 1 kWp) for the given location in the UK. Part of the electricity produced is used directly by the household (self-consumption), while the rest is exported to the grid under the Smart Export Guarantee (SEG).
Annual savings are the sum of two parts: money saved on electricity that would otherwise have been bought (self-consumption × electricity price), and income from surplus exported to the grid (remaining production × SEG rate).
The payback period is the year in which cumulative savings exceed the net investment (system and any battery price, minus any subsidy). The calculator also accounts for the annual rise in electricity prices and the gradual degradation of panel output.
The calculator lets you compare 2–3 setups side by side, for example a system without a battery and one with a battery, and immediately see the difference in payback period and total savings.
Frequently asked questions
How many years does it take a 7 kWp solar system to pay back in the UK?
For a 7 kWp system without a battery and an annual household consumption of 6,000 kWh, the payback period is 5.39 years. The annual saving is £1,261 and the monthly electricity bill drops from £130 to £72.
How much do I save with a 7 kWp solar system in the UK per year?
For the default 7 kWp system without a battery, the annual saving is £1,261, and £37,870 over the full 25-year system lifetime.
How much does self-generated kWh cost compared to the grid in the UK?
Self-generated electricity costs around £0.04/kWh, which is 85% cheaper than the £0.26/kWh bought from the grid (2026 prices).
How is the annual solar production calculated?
Multiply the system size in kWp by the location's specific yield in kWh/kWp/year. In the UK, the typical figure is around 1000 kWh/kWp/year in the south-east, ranging from around 750 kWh/kWp/year in northern Scotland to 1050 kWh/kWp/year on the south coast.
What does self-consumption mean and why does it matter?
It's the share of produced electricity you use directly instead of exporting it to the grid. Higher self-consumption means a faster payback, because purchased electricity is more expensive than the SEG export rate for surplus.
Is battery storage worth it?
A battery increases self-consumption and therefore savings, but also increases the investment. Compare the setup with and without a battery in the calculator – the higher the electricity price and daytime usage, the sooner a battery pays off.
What is the Smart Export Guarantee (SEG)?
Since the older Feed-in Tariff (FIT) closed to new applicants in 2019, the SEG is the main scheme for exporting surplus solar electricity to the grid in the UK. Rates vary widely between suppliers and tariff types, from a few pence per kWh on basic fixed tariffs to much higher rates on premium or agile tariffs paired with a battery.
Why does production decrease over time?
Solar panels gradually lose a small amount of output over time (degradation, typically around 0.5% per year). The calculator accounts for this in the production and savings estimate over the system's full lifetime.
How much CO₂ does a home solar system save?
It depends on annual production and the emissions factor of the Great Britain electricity grid. The calculator converts the electricity produced into tonnes of CO₂ saved per year based on the current energy mix.
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Last updated: 24 July 2026