greenhomesums

Solar Payback by Postcode UK

UK regional solar calculator — see solar panel payback, 25-year savings and annual generation for your postcode. Powered by JRC PVGIS satellite data.

Postcode solar payback calculator

Worked example

A 4 kWp system on a typical UK home using 3,500 kWh/yr of electricity, with UK-average irradiance:

System 4.0 kWp
Generation 3800 kWh/yr
Year-1 saving £730
Payback 8.5 yrs
25-yr net benefit £23185

Solar payback by UK region

Sample results for a 4 kWp, no-battery system across major UK cities. All figures use the same £7,200 install cost, 27p/kWh tariff, 15p/kWh SEG export and 4%/yr inflation — the only thing varying is the local PVGIS irradiance.

City Outcode Region kWh/kWp/yr Year-1 saving Payback 25-yr benefit
London SW1A Greater London 975 £749 8.3 yrs £23984
Manchester M1 North West England 890 £684 9.0 yrs £21266
Birmingham B1 West Midlands 930 £714 8.6 yrs £22545
Leeds LS1 Yorkshire 900 £691 8.9 yrs £21586
Glasgow G1 Scotland 850 £653 9.3 yrs £19986
Edinburgh EH1 Scotland 870 £668 9.1 yrs £20626
Cardiff CF10 Wales 970 £745 8.3 yrs £23825
Belfast BT1 Northern Ireland 880 £676 9.0 yrs £20946
Newcastle NE1 North East England 880 £676 9.0 yrs £20946
Liverpool L1 North West England 900 £691 8.9 yrs £21586
Sheffield S1 Yorkshire 905 £695 8.8 yrs £21746
Nottingham NG1 East Midlands 925 £710 8.7 yrs £22385
Bristol BS1 South West England 990 £760 8.2 yrs £24464
Southampton SO14 South East England 1020 £783 8.0 yrs £25424
Brighton BN1 South East England 1035 £795 7.9 yrs £25903

Irradiance figures are representative PVGIS values for each outcode (south-facing, 35° tilt). Enter your exact postcode above for location-specific numbers.

Frequently asked questions

How does my postcode affect solar payback?
Postcode determines your local solar irradiance — roughly how many kilowatt-hours each kWp of panels will generate per year. A 4 kWp system in sunny Brighton (≈1,035 kWh/kWp) produces about 22% more energy than the same system in Glasgow (≈850 kWh/kWp), which shortens payback by a year or two.
Where does the irradiance data come from?
From PVGIS, the European Commission Joint Research Centre's open satellite-derived solar dataset. We look up your outcode's coordinates and ask PVGIS for the expected annual yield for a south-facing, 35° tilt system — the UK-typical installation.
What are the default assumptions?
4 kWp system, no battery, 3,500 kWh/yr household usage, 27p/kWh import tariff, 15p/kWh SEG export rate, £7,200 install cost, 4%/yr electricity inflation. All of these are adjustable under "Adjust assumptions".
How is this different from your main solar calculator?
This page is postcode-first with confident defaults, designed to answer "what's the payback in my area?" in one look. For full scenario comparison, battery modelling and stress tests, use the full Solar Panel Savings Calculator.

How this calculator works

Solar Payback by Postcode is a deliberately simplified, location-first version of our full Solar Panel Savings Calculator. The idea is to answer one question fast — "what's the payback in my area?" — without asking you to understand SCOP, SEG or self-consumption terminology up front. Enter a UK postcode, pick a system size, and the page pulls a representative PVGIS irradiance figure for your outcode and plugs it into the same underlying cash-flow model used on the full calculator. Everything else — £7,200 install cost, 27p/kWh import, 15p/kWh SEG export, 3,500 kWh/yr household use, 4%/yr electricity inflation — uses confident 2026 UK defaults.

PVGIS is the European Commission Joint Research Centre's open dataset, built from decades of satellite-measured solar radiation data. For a south-facing roof at around 35° tilt — the UK-typical pitch — it returns annual specific yield in kWh per kWp. We look up your outcode's representative coordinates, query PVGIS, and feed the number into the payback model. The difference between a cloudy 850 kWh/kWp in the Scottish lowlands and a sunny 1,035 kWh/kWp on the Sussex coast is roughly 22% more generation, which on the same 4 kWp system typically shortens payback by 12–18 months.

Common pitfalls and things people get wrong

  • Postcode is a proxy, not a guarantee. We map your outcode (e.g. SW1A) to a representative latitude and longitude, then PVGIS quotes a yield for that point. If you live on a north-facing slope, behind a hill, or next to a large tree, your own yield can be 10–25% below the headline figure for your area.
  • The default assumptions are friendly. We use £7,200 installed (a fair mid-market 2026 price for 4 kWp), 27p/kWh import (the current Ofgem cap ballpark), and 15p/kWh SEG (Octopus Outgoing-level). If your quote is £9,500 and your SEG is 5p, your real payback is longer than the headline — use the full calculator to model your own numbers.
  • Regional cloud vs regional irradiance. Many people assume Glasgow is "hopeless" for solar. In reality, Glasgow at 850 kWh/kWp still generates meaningfully — a 4 kWp system puts out around 3,400 kWh/yr and saves a typical household £500–£600 in year one. Solar is worthwhile across the whole UK; it is just more-worthwhile in the south.
  • Panel quality is flattened out. Modern Tier-1 panels all sit within a narrow band of real-world performance. The single biggest swing in yield for a given postcode is orientation and shading, not which brand of panel the installer proposes.

UK-specific context

The UK's retained VAT zero-rating on solar and battery installs runs to at least March 2027, which is a material saving versus the rest of Europe. Most UK DNOs (Distribution Network Operators) now permit up to 3.68 kW export per phase under G98 without prior approval — so a single-phase home can usually install any size system and export-limit to 3.68 kW in the inverter settings. If you want to export more than that, your installer applies under G99, which is routine but adds 4–8 weeks to commissioning. The SEG market is competitive: rates refresh roughly yearly, and switching export supplier is a 10-minute task.

When this isn't the right answer

This postcode tool is a quick-look. It does not let you model a battery, an east-west roof split, different household usage, time-of-use tariffs, or the impact of an EV. If any of those apply to you, hop over to the full Solar Panel Savings Calculator — same engine, more levers, more honest scenario comparison. And if you are in a flat with no south-facing roof, or considering ground-mount solar on a smallholding, please do not rely on an outcode-level yield number; get a site survey.

Related calculators