Solar Panel Calculator UK: Cost, Savings & Payback
Estimate what solar could cost and save for your home in seconds. Enter your roof and usage below — free, no sign-up, honest 2026 figures.
How to use this calculator
Our free solar panel calculator gives you an instant, honest estimate of what a solar system could cost and save for your UK home. Just set four things above: your system size (drag the slider — it shows the rough panel count), your roof direction, your yearly electricity use (find it in kWh on your energy bill), and whether to add a battery. The results update instantly, showing your estimated annual output, installed cost, yearly saving and payback time.
Unlike many calculators, ours uses realistic 2026 figures, not optimistic ones — so it won’t oversell solar. It’s a genuine first answer to “is solar worth it for me, and what will it cost?” For the precise numbers, use it to get your ballpark, then get real quotes to confirm. Below: how the calculation works (so you can trust it), what affects your real numbers, and the cost and savings context.
How the calculator works (the honest methodology)
We believe a calculator should show its workings, so here’s exactly how ours estimates your numbers — all using verified 2026 UK figures:
- Output: your system size × ~975 kWh per kWp a year (for a south-facing roof), adjusted by orientation — south ×1.0, east/west ×0.8, north ×0.55. See our solar output by month guide for the generation detail.
- Cost: around £1,500 per kWp installed (with 0% VAT), plus ~£4,000 if you add a battery — in line with our full solar panel cost guide.
- Savings: we split your generation into self-consumed and exported. Without a battery a typical home uses ~35% directly; with a battery, ~75%. Self-consumed units save the import price (~26p/kWh); exported units earn the SEG export rate (~13p/kWh).
- Payback: installed cost ÷ annual saving.
These are deliberately middle-of-the-road, honest assumptions — real results vary, but the estimate is a sound guide. The Energy Saving Trust also offers an official calculator if you’d like a second reference.
What affects your real numbers
The calculator gets you a solid ballpark, but a few things it can’t see will shift your actual figures — which is why a real quote matters:
- Location & sunshine — the south coast generates noticeably more than northern Scotland.
- Roof pitch & shading — chimneys, trees and a shallow or steep pitch change output.
- Your usage pattern — being home in the day lifts self-consumption (and savings) above our 35% average.
- Your tariff — a smart tariff boosts battery savings beyond our estimate.
- Equipment & install — the panels, inverter and scaffolding needs affect the price.
Cost & savings: the context
To sense-check what the calculator shows you, here’s the 2026 picture. A typical 4kW system costs around £5,500–£8,000 installed and saves £500–£900 a year; a 5kW system £7,000–£9,000; a 6kW system £7,000–£9,500. Payback usually lands in the 6–12 year range on a system that lasts 25+ years — so most of its life is profit. Adding a battery increases both the cost and the savings; whether it’s worth it depends on your usage and tariff, which our are solar batteries worth it? guide walks through. For the full cost breakdown, see our solar panel cost guide, and for the buy-now question, are prices falling?. The calculator brings all of this together into your personal estimate — but remember it’s exactly that, an estimate: the way to know your real numbers is a proper quote.
Frequently asked questions
How accurate is a solar panel calculator?
A good ballpark — typically within 10–20% of a real quote. Ours uses realistic 2026 figures (~£1,500/kWp, ~975 kWh/kWp south, current prices), so it’s a reliable guide to whether solar makes sense. But it can’t see your exact pitch, shading, local sunshine or installer pricing — so use it for the estimate, then get 3 MCS quotes to confirm.
How do you calculate solar savings?
Generation (system size × ~975 kWh/kWp, adjusted for direction) split into self-consumed (saves ~26p import) and exported (earns ~13p SEG). A 4kW south system using 35% directly saves ~£700/yr. A battery raises self-consumption to ~75%, increasing savings. The calculator does this automatically.
How many solar panels do I need?
Most homes need 8–16 panels (3–6kW): ~8 for a 1–2 bed, ~10 for a 3-bed, ~12–13 for a 3–4 bed, 14+ for a large home or one with an EV/heat pump. Match the system to your annual kWh use. Our roof-fit guide covers the space side; the calculator estimates size from your usage.
Does it include a battery?
Yes — toggle the battery on and it adds ~£4,000 to the cost and raises self-consumption from ~35% to ~75%, so you see cost, savings and payback with and without storage. It uses a standard assumption; a smart tariff can add £150–£400/yr more. See are batteries worth it?
Is the calculator free?
Completely free — no sign-up, no email, no obligation. Enter your details for instant estimates of size, cost, savings and payback. If the numbers look good, you can optionally get free quotes to confirm, but there’s no requirement. We’re independent, not an installer.
What should I do with the results?
Use them as your honest starting point. If solar looks worthwhile, get at least three quotes from MCS-certified installers to confirm the exact cost, savings and payback for your roof — a survey accounts for the things a calculator can’t. If the numbers don’t stack up, you’ve saved yourself time.
From estimate to real numbers
This calculator gives you the fast, honest first answer to what solar could cost and save for your home — using realistic 2026 figures rather than the optimistic ones some tools rely on. Play with different system sizes, try your roof direction, and toggle the battery to see how the numbers change. It’s a genuinely useful way to work out whether solar is worth exploring for you, and roughly what to expect, before you speak to anyone.
But an estimate is just that. Your real cost and savings depend on your specific roof, location, shading, tariff and the installer you choose — the things only a proper survey can capture. So if the calculator’s numbers look promising, the next step is simple: a couple of free, no-obligation quotes from MCS-certified installers will turn your estimate into precise, tailored figures you can rely on — and let you compare like-for-like before you commit.
Important
Going Solar UK is an independent introduction service, not an installer. This calculator provides estimates for general guidance only, using typical 2026 UK figures: your actual system size, cost, savings and payback depend on your specific property, roof orientation and pitch, shading, location, electricity usage, tariff, equipment and installer, and on energy prices which change frequently. The figures shown are not quotes, guarantees or financial advice. Always obtain professional surveys and itemised quotes from MCS-certified installers for your specific home before making any decision.
We may receive a commission when we introduce you to an installer, at no cost to you. Any contract for work is directly between you and the installer.