UK assumptions checked 2 June 2026
Solar savings calculator for UK homes
Use this as a solar savings estimate, payback calculator and quick checker for how import rates, SEG export income and batteries change the result.
£311 saved + £351 exported
Middle-ground payback: small tariff or usage changes matter.
Benefit x 20 minus upfront cost, before maintenance or degradation
Transparent method
How this UK solar savings estimate works
The calculator splits annual solar generation into electricity used at home and electricity exported to the grid. Self-used electricity is valued at your import unit rate. Exported electricity is valued at your export tariff. The annual benefit is the two numbers added together.
That means a good solar savings estimate needs more than one headline number. A system can look excellent if every kWh is valued at the import rate, but real homes usually export some power. The checker keeps that split visible so you can compare quotes without relying on optimistic sales assumptions.
Payback is deliberately simple: upfront cost divided by annual benefit. That keeps the result easy to audit. It doesn't assume future tariff inflation, finance costs, maintenance, inverter replacement or panel degradation, so run conservative and optimistic cases before relying on one result.
Useful next checks
What usually improves solar payback?
FAQs
Common questions
How accurate is this solar savings calculator?
It is a transparent estimate based on the assumptions you enter. Real results vary by roof orientation, shading, household usage, installer pricing, inverter performance, tariff changes and metering arrangements.
What electricity unit rate should I use?
Use your actual tariff if you know it. The default is aligned to the Ofgem average Direct Debit electricity unit rate for 1 April to 30 June 2026, rounded to 24.7p/kWh. Ofgem has announced 26.11p/kWh for 1 July to 30 September 2026, so the calculator should be updated again when that period starts.
What export rate should I enter?
Use the SEG export tariff you can actually access. Ofgem requires eligible SEG tariffs to be above zero, but suppliers set the rate and contract terms.
Does a battery always improve payback?
No. A battery can increase self-consumption, but it adds upfront cost. The comparison table shows whether the extra annual benefit offsets that added cost under your assumptions.
How do I calculate solar savings?
Estimate annual generation, split it into the amount used at home and the amount exported, then value each bucket. Self-used kWh are valued at your import unit rate. Exported kWh are valued at your export tariff. Add those two figures for the annual benefit.
Is this a solar savings checker or a final quote?
It is a savings checker and planning estimate. It helps you test a quote, but it can't replace a roof survey, installer design, DNO paperwork or the export tariff terms you can actually access.
Does the calculator include maintenance or inverter replacement?
No. The headline payback uses simple upfront cost divided by annual benefit. For a conservative view, increase the upfront cost or reduce expected annual generation.
Accuracy note
Sources reviewed 2 June 2026
- Ofgem energy price cap unit ratesDefault uses the Direct Debit electricity unit rate for 1 April to 30 June 2026: 24.67p/kWh, including VAT. Ofgem has announced 26.11p/kWh for 1 July to 30 September 2026.
- Energy Saving Trust solar panel guideAverage domestic solar PV system: around 3.5kWp and about £6,100, 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.