UK solar panel savings examples by system size
This page compares example savings across several common system sizes; it is not a personalised calculator or a step-by-step formula guide. Solar value comes from using your own electricity instead of buying it from the grid, plus payments for electricity exported through a SEG or export tariff.
The examples below use the current 26.32p/kWh Ofgem Direct Debit electricity context, this calculator's current 4.1p/kWh standalone export planning rate and 35% self-consumption. The installed costs are illustrative scenario values, not current market averages or quotes.
Example solar savings by system size
| Scenario | Annual benefit | Bill saving | Export income | Payback |
|---|---|---|---|---|
| 3kW compact roof Smaller roof, no battery, middle yield. | £321 | £249 | £72 | 17.2 years |
| 4kW typical case Illustrative 3,600kWh annual generation, no battery. | £428 | £332 | £96 | 16.4 years |
| 5kW higher generation Larger array, same tariff assumptions, no battery. | £534 | £415 | £120 | 15.9 years |
What makes the biggest difference?
- Generation:a south-facing, unshaded roof in a strong location won't behave like a shaded roof split across several faces.
- Self-consumption: the more solar you use at home, the more kWh are valued at your import rate rather than your export rate.
- Export tariff: SEG and export rates vary by supplier, tariff type and eligibility rules.
- Installed cost: scaffolding, roof work, inverter choice, battery storage and warranty support can move payback by years.
How to use this before buying solar panels
- Start with the calculator default to understand the moving parts.
- Replace the unit rate with your actual electricity tariff.
- Replace annual generation with a PVGIS or installer estimate.
- Run a 10% lower generation case to avoid relying on the best case.
- If your quote includes storage, complete solar-only first, then use the current battery comparison with usable capacity and incremental installed battery cost.
Solar savings FAQs
How much can solar panels save in the UK?
It depends on annual generation, how much solar electricity you use at home, your import unit rate, your export tariff and the installed cost. The examples on this page show how quickly the answer changes.
Should I use the current Ofgem unit rate?
Use your actual tariff if you know it. The worked examples use the current 26.32p/kWh Ofgem Direct Debit electricity context from 1 October 2026 to 31 December 2026.
Does exported electricity count as a saving?
It is better to treat export as income rather than a bill saving. The total annual benefit is bill saving from self-used solar plus export income.
Accuracy note
Sources checked
- Ofgem energy price cap unit ratesCurrent Direct Debit electricity unit rate: 26.32p/kWh from 1 October 2026 to 31 December 2026. Evidence rechecked 7 October 2026.
- Energy Saving Trust solar panel guideAverage domestic solar PV system: around 4.5kWp and about £7,600, with roof direction, shade and access changing the final quote.
- Energy Saving Trust battery storage guideBattery storage costs vary by size and type. Energy Saving Trust says a 5kWh battery system is around £4,600, with wider costs ranging from £1,500 to £10,000.
- Ofgem Smart Export Guarantee guidanceSEG export tariffs are set by suppliers, must be above zero, and require eligible metered exports.
- European Commission PVGISPVGIS provides location-specific solar radiation and photovoltaic performance estimates.
Next: run your own solar savings estimate · follow the savings formula · compare export tariffs · inspect the 4kW worked example · check solar panel costs · compare battery payback