Do Solar Panels Work on Cloudy Days?
Yes. UK solar panels generate electricity on cloudy days — typically at 10–25% of their peak sunny-day output, depending on cloud thickness. Panels respond to diffuse daylight, not just direct sunshine, which is why the UK still produces comparable annual yields to parts of Germany and Belgium.
Quick Answer
Solar panels generate 10–25% of peak output on cloudy days and 30–60% on hazy or lightly overcast days. The UK's mostly-cloudy climate still delivers 3,400–4,200 kWh per year from a typical 4kWp system — enough to offset most household daytime electricity use.
How do solar panels work in cloudy weather?
Solar panels generate electricity from photons — light particles. Clouds scatter and reduce the amount of light reaching your roof but do not block it entirely. The diffuse daylight that gets through still contains enough photons to produce power, just at a lower rate than direct sunshine.
This is why the UK — one of the cloudiest countries in Europe — still has a viable solar industry. Panel efficiency under diffuse light has improved significantly with N-type TOPCon cells, which are standard in 2024–2025 installations.
Solar panel output by cloud cover
| Sky conditions | % of peak output | Example (4kWp system at noon) |
|---|---|---|
| Clear sunshine | 100% | ~4,000 W |
| Light haze / thin cloud | 50–60% | 2,000–2,400 W |
| Overcast (typical UK day) | 20–30% | 800–1,200 W |
| Heavy dark cloud / rain | 10–15% | 400–600 W |
| Dusk / near darkness | <5% | <200 W |
Based on irradiance values from the UK Met Office and typical panel response curves for 440W N-type TOPCon modules.
Does the UK get enough sun for solar?
Yes. The UK receives between 900 and 1,100 kWh/m² of solar irradiance per year, depending on location. That is lower than southern Spain (1,800+) but comparable to northern Germany, Belgium, and the Netherlands — all countries with thriving solar industries.
Southern England receives around 15–20% more annual sunshine than Scotland, which is why systems in Cornwall, Devon, and Kent produce more than identical systems in Aberdeen or Inverness. See our Scotland solar guide and UK solar panel output guide.
Frequently Asked Questions
How much do clouds reduce solar panel output?
Heavy cloud cover reduces output to around 10–25% of peak. Light haze or thin cloud reduces it to around 50–60%. The UK averages 70–80% cloud cover on typical days, which is why annual yields are lower than southern Europe but still commercially viable.
Do solar panels need direct sunlight?
No. Solar panels generate from diffuse daylight as well as direct sunshine. Direct sunlight produces the highest output, but panels continue generating on cloudy, overcast, and hazy days.
Do solar panels work in the rain?
Yes, although at reduced output (typically 10–15% of peak). Rain actually helps solar panels by washing off dust and pollen, improving long-term efficiency.
Are solar panels worth it in cloudy climates like the UK?
Yes. UK payback periods are typically 6–8 years, and systems pay for themselves several times over during their 25–30 year lifespan. See our guide on whether solar panels are worth it in the UK.
Does fog affect solar panels?
Yes — dense fog reduces output similarly to heavy cloud, to around 10–20% of peak. But fog usually clears during the day, so morning-only fog has limited impact on daily yield.
Related solar performance guides
Related Guides
Solar Panels in Winter
Winter output data, monthly breakdown, and performance tips.
Solar Panel Output
How much electricity solar panels produce by system size in the UK.
How Solar Panels Work
Plain-English guide to solar PV technology.
Do Solar Panels Work at Night?
How batteries and tariffs bridge the night-time gap.
Sources
- UK Met Office — Solar radiation data — metoffice.gov.uk
- European Commission — PVGIS Solar Radiation Database — re.jrc.ec.europa.eu
Last updated: April 2026
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He fact-checks all content against official MCS and Ofgem data and maintains relationships with MCS-certified installers across the UK.
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