UK Solar Hours by Region · NASA POWER · Updated 24 May 2026
UK Peak Sun Hours by Region — Month by Month
2.79 peak sun hours per day is the UK 17-city average. Cornwall and the south coast top out at 3.17–3.28; the Scottish Highlands sit at 2.29. Each region's peak month — June for southern and central England, May for Scotland — ranges from 4.46 to 6.00 kWh/m²/day. December bottoms out at 0.26–0.67.
All figures below are peak sun hours per day (kWh/m²/day), taken directly from NASA POWER satellite climatology (parameter ALLSKY_SFC_SW_DWN, 20-year mean, January 2001 – December 2020, SYN1DEG source). Fetched per-city via the public NASA POWER API on 24 May 2026.
| Region | Postcode | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Penzance / Cornwall | TR | 0.82 | 1.61 | 2.80 | 4.47 | 5.43 | 5.81 | 5.36 | 4.56 | 3.47 | 1.96 | 1.04 | 0.65 | 3.17 |
| Brighton / Eastbourne | BN | 0.85 | 1.59 | 2.87 | 4.58 | 5.53 | 6.00 | 5.79 | 4.80 | 3.57 | 1.98 | 1.03 | 0.67 | 3.28 |
| Southampton | SO | 0.85 | 1.59 | 2.87 | 4.58 | 5.53 | 6.00 | 5.79 | 4.80 | 3.57 | 1.98 | 1.03 | 0.67 | 3.28 |
| London | EC/SW | 0.84 | 1.51 | 2.64 | 4.04 | 4.87 | 5.30 | 5.09 | 4.19 | 3.23 | 1.85 | 0.99 | 0.66 | 2.94 |
| Bristol | BS | 0.80 | 1.49 | 2.66 | 4.11 | 5.02 | 5.32 | 5.04 | 4.16 | 3.22 | 1.81 | 0.96 | 0.62 | 2.94 |
| Cardiff | CF | 0.80 | 1.49 | 2.66 | 4.11 | 5.02 | 5.32 | 5.04 | 4.16 | 3.22 | 1.81 | 0.96 | 0.62 | 2.94 |
| Norwich / East Anglia | NR/IP | 0.75 | 1.45 | 2.62 | 4.10 | 4.93 | 5.16 | 4.99 | 4.19 | 3.18 | 1.81 | 0.92 | 0.60 | 2.90 |
| Birmingham | B | 0.77 | 1.48 | 2.60 | 3.98 | 4.91 | 5.13 | 4.99 | 4.11 | 3.12 | 1.78 | 0.95 | 0.63 | 2.88 |
| Manchester | M | 0.64 | 1.33 | 2.52 | 3.93 | 4.90 | 5.05 | 4.81 | 4.01 | 2.89 | 1.60 | 0.79 | 0.49 | 2.75 |
| Leeds / West Yorks | LS/BD | 0.68 | 1.37 | 2.47 | 3.83 | 4.77 | 4.84 | 4.77 | 3.92 | 2.94 | 1.66 | 0.84 | 0.54 | 2.73 |
| Hartlepool / Teesside | TS | 0.62 | 1.26 | 2.37 | 3.74 | 4.73 | 4.73 | 4.62 | 3.78 | 2.81 | 1.53 | 0.76 | 0.46 | 2.62 |
| Sunderland / Wearside | SR | 0.62 | 1.26 | 2.37 | 3.74 | 4.73 | 4.73 | 4.62 | 3.78 | 2.81 | 1.53 | 0.76 | 0.46 | 2.62 |
| Newcastle upon Tyne | NE | 0.62 | 1.26 | 2.37 | 3.74 | 4.73 | 4.73 | 4.62 | 3.78 | 2.81 | 1.53 | 0.76 | 0.46 | 2.62 |
| Edinburgh | EH | 0.55 | 1.20 | 2.25 | 3.66 | 4.70 | 4.57 | 4.40 | 3.65 | 2.64 | 1.46 | 0.71 | 0.40 | 2.52 |
| Glasgow | G | 0.50 | 1.19 | 2.32 | 3.77 | 4.77 | 4.75 | 4.49 | 3.67 | 2.60 | 1.42 | 0.67 | 0.37 | 2.55 |
| Aberdeen | AB | 0.44 | 1.10 | 2.15 | 3.59 | 4.63 | 4.53 | 4.43 | 3.52 | 2.51 | 1.34 | 0.58 | 0.30 | 2.43 |
| Inverness / Highlands | IV | 0.38 | 0.98 | 2.01 | 3.43 | 4.46 | 4.35 | 4.10 | 3.33 | 2.36 | 1.26 | 0.53 | 0.26 | 2.29 |
Amber highlights mark each region's peak month. Southern and central England (Penzance through Leeds) peak in June; Scotland (Edinburgh, Glasgow, Aberdeen, Inverness) peaks in May because high-latitude June cloud cover offsets the longer day length. The north-east trio (Hartlepool/Sunderland/Newcastle) is effectively tied at 4.73 across May and June. Cities sharing identical values (Brighton/Southampton, Bristol/Cardiff, Hartlepool/Sunderland/Newcastle) fall within the same 1° NASA POWER grid cell — use the postcode calculator for higher-resolution figures.
How to estimate your UK solar kWh
For any month, your expected generation is:
kWh = system_kWp × peak_sun_hours × days_in_month × 0.80
The 0.80 factor (the "performance ratio") accounts for real-world losses: inverter efficiency, cable losses, panel soiling, temperature derating, and orientation tilt. Premium installations may hit 0.85; budget kits 0.70.
Worked example. A 4 kWp rooftop system in Manchester in May: 4 × 4.90 × 31 × 0.80 ≈ 486 kWh. An 800W plug-in kit in Edinburgh in March: 0.8 × 2.25 × 31 × 0.80 ≈ 45 kWh.
What the numbers mean in practice
South vs North gap is ~28%
Penzance averages 3.17/day; Inverness 2.29. That's a 28% spread — meaningful but not disqualifying. A 4 kWp system in the Highlands still generates ~2,700 kWh/year (saving ~£700 at 26p/kWh).
May–July dominates
These three months account for ~40% of annual UK solar generation. June alone delivers more than December, January, and February combined.
Winter is brutal but brief
December and January together produce only ~8% of annual output. Plan winter electricity needs around grid or battery, not solar — even Cornwall sees just 0.65–0.82 kWh/m²/day in December.
Plug-in solar works UK-wide
An 800W kit in any UK region generates 600–950 kWh/year. With UK electricity at 24–28p/kWh and SEG export up to 15p, payback runs 3–6 years on a £350–£500 kit nationwide.
Source and citation
Dataset: NASA POWER (Prediction Of Worldwide Energy Resources) ALLSKY_SFC_SW_DWN climatology. All-Sky Surface Shortwave Downward Irradiance, kWh/m²/day. 20-year monthly mean covering January 2001 – December 2020. SYN1DEG source.
API endpoint: https://power.larc.nasa.gov/api/temporal/climatology/point?parameters=ALLSKY_SFC_SW_DWN&community=RE&longitude={lon}&latitude={lat}&format=JSON
Fetched: 24 May 2026, one call per city using its centroid lat/lon. NASA POWER provides global climatology free at the point of use under their API license.
Methodology note: NASA POWER uses a 1° latitude/longitude grid, so cities within the same grid cell share values. For postcode-exact figures, use the SolarUK postcode calculator, which queries NASA POWER live for your specific GPS coordinates.
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Want a forecast for your specific system?
Sun Hours uses NASA POWER plus live cloud-cover data to give you a 7-day kWh forecast for your exact UK postcode. Two-question setup. No account. Free on Android.