A satellite-modelled annual generation estimate for your exact roof — any UK postcode, any orientation, up to four arrays — plus what it's worth in pounds.
📡 EU PVGIS satellite irradiance data📍 Works from your postcode💷 Savings & export earnings included
Installers quote generation from a standard table. This tool instead asks the EU's PVGIS service — nearly 20 years of satellite-measured sunlight for your actual location — so east-, west- and even north-facing roofs get a fair, realistic number.
👋 Welcome back — loaded your saved setup and fetched today's forecast.
Step 1
📍 Where is the roof?
Step 2
◱ Your solar array(s)
Panels facing different directions? Add each group as its own array — like 9 panels south + 9 panels north — and we'll model each separately.
Optional
⚙️ Advanced settings
▼ show
10%
Cabling, inverter efficiency, dirt, downtime. PVGIS' old default was 14%; ~8–10% suits modern kit (microinverters/optimisers: use 8%).
Modern panels lose slightly less output on hot days (better temperature coefficient).
⚠️ The PVGIS satellite service couldn't be reached just now, so these figures use our built-in UK irradiance model instead — a good approximation, but re-run later for the satellite-modelled numbers.
Annual generation
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Worth per year
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bill savings + export earnings
Specific yield
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kWh generated per kWp installed — the fair way to compare systems
⛅ Today & tomorrow
Live weather-based forecast for your array(s) at this location — data by Forecast.Solar, the same service Homey and Home Assistant use.
Today
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Tomorrow
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Forecasts update through the day as the weather model refreshes.
Month by month
Estimated generation, kWh per month
💷 What it's worth
Adjust the assumptions — the figures update instantly.
35%
Typical: 25–40% without a battery · 60–90% with one.
26p
Your unit rate, p/kWh. Check your bill.
15p
What you're paid per exported kWh. Best SEG tariffs pay ~15p; the worst under 5p — see our Tariff Finder.
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