Should you clean solar panels in winter?

Yes, solar panels can be cleaned in winter, and for some homes late autumn is one of the most useful times to do it. Your panels make much less electricity between November and February, so anything blocking light during those months takes a bigger share of what little they produce. The exceptions are frost, ice and snow, which need a different approach.

Here is how winter changes things, and how to decide whether a clean is worth booking now or waiting until spring.

Do solar panels still work in winter?

They do. Panels generate from daylight, not heat, so they keep working on cold and cloudy days. Output is lower because the days are shorter and the sun sits lower in the sky. As a national guide, E.ON Next estimates UK panels produce only around 10 to 25 percent of their yearly energy between December and February.

Cold itself is not the problem. The same E.ON Next guide notes that panels tend to run slightly more efficiently in cool weather than on a hot summer day. The loss is all about the amount of light reaching the cells.

Why dirt matters more in winter

When the sun is low, light hits the glass at a shallow angle. Any film of grime, pollen or traffic dirt scatters more of that light before it reaches the cells. Bird droppings and lichen block it completely, whatever the season.

Autumn also adds its own mess. Leaves collect along the bottom edge of panels, especially where an array sits under or near trees, and wet leaves stain the glass as they break down. Around Keynsham, Saltford and the greener edges of Bath and north Bristol, that is often the main reason panels look tired by November.

If you want to understand what builds up and why rain does not shift it, our guide on whether solar panels need cleaning covers it in more detail.

When a winter clean makes sense

• Your panels have not been cleaned for a year or more
• You can see leaves, bird mess or green edges from the ground
• Your monitoring app shows a drop that does not match the weather
• The array sits under trees, near farmland or close to a busy road
• You want the panels as clear as possible to make the most of short days

If your panels were cleaned in late summer and look clear, there is usually no need to rush. A yearly clean suits most homes in this area, and we will tell you honestly if yours can wait.

Frost, ice and snow

These are the times to leave your panels alone.

Frost and ice

Do not try to scrape frost or ice off the glass, and do not pour hot water on cold panels. Scraping scratches the glass and the anti-reflective coating, and a sudden temperature change puts stress on cold glass. Frost on a sloping panel usually clears by itself once the sun is on it.

Snow

Tilted panels tend to shed snow on their own, and generation starts again once enough light gets through. E.ON Next advises against climbing onto the roof to clear snow, and warns that clearing it with tools can scratch the panels. If output stays at zero for several days after the snow has gone, check your inverter or monitoring app, and contact your installer if something looks wrong.

Can solar panels be cleaned in the cold?

Yes, on a dry day above freezing. We clean from the ground with deionised water and a soft brush on a telescopic pole, so there is no roof walking. Freezing conditions are the limit, because water left on glass, paths or drives can turn to ice. In that case the clean is simply moved to a milder day.

The short days do mean less working light, so winter cleans tend to be booked for the middle of the day.

Doing it yourself in winter

If your panels are on a ground mount or a low single-storey roof, a gentle wash with plain water and a soft brush on a dry, mild day is fine. Switch the system off first following your installer's instructions. Our step by step guide on how to clean solar panels safely explains what to use and what to avoid. Never climb onto a wet or frosty roof.

Book a winter solar panel clean

We clean domestic arrays across Keynsham, Bristol and Bath, and larger roofs through our commercial solar panel cleaning service. See how our solar panel cleaning works, or get in touch with your postcode and a photo of your array. You can also call Tom on 0117 279 0045 for a free quote.