Servicing · Guide
Do solar panels work in winter?
Yes. Solar panels generate electricity from daylight, not heat, and they don’t need direct sunshine. The Energy Saving Trust notes that panels can work even on cloudy days. What changes in winter is how much they produce, not whether they work.
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Why it drops
Why winter output is lower.
- Shorter days. In December there are far fewer hours of usable daylight than in June.
- Low sun. The sun sits low in the sky, so its light reaches the panels at a shallower angle and through more atmosphere.
- More cloud, and grey days that run into each other.
- Longer shadows. A tree, chimney or neighbouring roof that never shades your panels in summer can shade them for much of a winter day.
Cold on its own isn’t the problem. Solar cells work slightly more efficiently when they are cool, so a bright, frosty January morning can be a surprisingly good day for generation.
What to expect
What to expect from December to February.
Winter months produce a small fraction of what your system makes in summer: November to January together make only about a tenth of the year’s output (see how much electricity should my solar panels generate?). That is normal, and it is already built into the yearly estimate you were given when the system was fitted.
The mistake to avoid is comparing a winter month with a summer one. The only fair test is the same month last year:
- Similar total (allowing for a sunnier or duller month): your system is working as it should.
- Noticeably lower, and last winter wasn’t unusually bright: something may be wrong.
If you have a monitoring app, look at a bright winter day rather than a dull one. On a clear day, generation should rise through the morning and fall away in the afternoon in a smooth curve.
Spotting a fault
When low winter output is actually a fault.
Winter hides faults. Owners often put a poor December down to the weather when the system has actually stopped. Signs it’s more than the season:
- Nothing at all on a bright day, or the generation meter hasn’t moved in a week.
- A red or amber light or an error code on the inverter, or a blank screen at midday.
- A trip switch for the solar circuit that has gone off. Storms and power cuts can cause this.
- Output that stops at the same time every day, which can point to a new shading problem.
- A fault that appears in the morning and clears by lunchtime. On some systems this is damp in a connector or isolator. It often gets worse over the winter.
If any of these sound familiar, work through our checklist: solar panels not working?
Winter checks
Winter checks worth doing.
From the ground, without climbing anything:
- Look for leaves, moss and debris on the panels, especially on shallow roofs where rain doesn’t wash them clean. See solar panel cleaning.
- Check for new shading from the low winter sun.
- After a storm, look for slipped panels or loose cables, and check the inverter is still running.
- Glance at the inverter and isolators. Water in an isolator housing, condensation behind the cover, or scorch marks all need an engineer.
Autumn is a sensible time for the yearly service. It is a chance to clean the panels, check the isolators are dry and tight before the wet months, and review the inverter’s fault log. See solar panel maintenance.
Snow
What about snow?
A light covering usually slides off a pitched roof within a day or so, helped by the dark glass warming in the daylight. Panels covered by snow produce little or nothing until it clears.
Don’t go on the roof to clear them. Don’t pour hot water on cold glass, and don’t scrape the surface. The output you lose from a few snowy days is small compared with the risk.
Batteries
Batteries in winter.
A solar battery may not fill from the panels on short winter days. Its job doesn’t stop, though. Depending on your tariff and battery, you may be able to charge it from the grid at a cheaper overnight rate and use that power at peak times.
If your battery has stopped charging or discharging at all, rather than just filling less, that is a fault worth checking. See how long do solar batteries last? For checks to try first, see solar battery not charging?
Sources: Energy Saving Trust, Solar panels: costs, savings and benefits explained (updated August 2026); PVGIS 5.3 (European Commission JRC), monthly figures for a south-facing roof near Manchester.
Questions
The things people ask before they ring.
Not answered here? Call 0800 156 0191, Monday to Friday, 9:00am–5:00pm.
Do solar panels work in the snow?
Only when the snow isn’t covering them. Light snow usually slides off a pitched roof quickly. Panels covered in snow produce little until it clears. Don’t climb up to clear them, and don’t use hot water on cold glass.
Do solar panels work on cloudy days?
Yes, at a lower output. Panels use daylight rather than direct sun, so they keep generating under cloud, just less than on a bright day.
Why is my inverter off in the morning and evening in winter?
Inverters switch themselves off when there isn’t enough light to generate, and switch back on when there is. In winter that means a later start and an earlier finish. A blank inverter at midday on a bright day is different: that needs checking.
Should I switch my solar panels off in winter?
No. Leave the system on all year. It generates whenever there is enough light, and switching it off and on isn’t good for the equipment or your generation total.
Ready when you are
Worried your winter generation looks wrong?
We’ll call you back to talk it through, and you get a clear written quote before any work starts. Mon–Fri 9:00am–5:00pm.