Yes, solar panels work in winter and on cloudy days. They run on daylight, not heat, so they keep making some power all year. However, the amount drops sharply from November to February.

For a typical 4 kWp system facing south near Birmingham, EU modelling puts December output at about 133 kWh. That compares with around 468 kWh in June. This guide shows the full month-by-month picture and what it means for your bills.

What a UK system makes each month

The best free guide is PVGIS, a tool from the European Commission’s Joint Research Centre. It uses satellite weather data from 2005 to 2023. We ran a 4 kWp system, tilted at 35 degrees and facing south, in the Midlands with 14% system losses.

The yearly total comes to about 3,870 kWh. Here is how the months stack up, in kWh:

  • January: 149, February: 206, March: 336
  • April: 433, May: 469, June: 468
  • July: 472, August: 425, September: 360
  • October: 251, November: 169, December: 133

Spring and summer do the heavy lifting. April to September makes about 68% of the year’s power. November to February together make about 17%. As a result, December and January add up to only around 7% of the year.

Why winter output falls

Three things cut winter output. Days are much shorter, the sun sits lower, and cloud is more common. Because the sun is low, light hits the panels at a shallow angle. For example, PVGIS gives about 133 kWh in December at a 35 degree tilt, but only about 77 kWh at 10 degrees.

How much cloud matters

Cloud blocks some light, yet panels still work in diffuse light. Season matters more than any single day, because the sun is so much lower in winter.

The PVGIS figures already include typical UK weather. You do not need to cut them again for cloud. However, any one week can be well above or below the average.

Where you live and which way you face

Location and roof direction change the winter result a lot. PVGIS gives these December estimates for the same 4 kWp system:

  • London, south roof: about 144 kWh
  • Birmingham, south roof: about 133 kWh
  • Glasgow, south roof: about 76 kWh
  • Birmingham, east or west roof: about 55 kWh

So a Scottish home, or one with east and west panels, will see a much thinner winter. Even so, those layouts can suit homes that use power in the morning and evening. Our guide to east-west and flat roof solar weighs that up.

What this means for your bills

Ofgem uses 2,500 kWh a year as the typical electricity use for a home from 1 July 2026. That is about 6.8 kWh a day. The Midlands system above makes about 4.3 kWh a day on average in December.

That sounds close, but it is not. Your panels peak at midday, when many people are out. Meanwhile, your use peaks in the evening, when the panels make nothing. In winter, you will still buy most of your power from the grid.

Plan for the year, not the month

Judge a system by its yearly result. Summer surplus can cover long, light evenings and also earn export payments. Our solar panel costs and savings guide shows how those savings add up. For the payback question, read are solar panels worth it.

Ways to get more from winter

You cannot make the sun shine. However, you can make better use of what you get.

  1. Size the system well. More panels raise winter output too. Our guide on how many solar panels you need explains the sums.
  2. Use power when it is made. Run the dishwasher or washing machine at midday on bright days. Our post on using more of your solar power has more ideas.
  3. Add storage. A battery holds midday power for the evening. Read solar battery cost and sizing before you decide.
  4. Check your tariff. Cheap night rates can fill a battery on dark days. See time-of-use tariffs with solar and batteries.

Questions to ask your installer about winter

A good installer should give you a monthly estimate, not just a yearly one. Ask which tool they used and which weather data it relies on. If they quote a figure much higher than PVGIS for the same roof, ask why.

Ask about your roof as well. A low tilt or an east-west layout will make less in December, as the figures above show. However, it may suit your daily routine better.

Finally, ask what the system does on a dark day. Some set-ups can charge a battery from the grid at cheap rates, while others cannot. The answer shapes your winter bills more than the panels do.

Does winter harm the system?

Low output is not damage. The panels simply sit idle at night and make less on dull days. Keep an eye on your monitoring app, though, because a sudden drop on a bright day can signal a fault.

Your inverter matters here too, so see solar inverters explained for what it does and what to ask about warranties. MCS says panels can last over 20 years, and our piece on solar panel lifespan and degradation looks at the detail. Read about cleaning and maintaining solar panels for safe methods. Our hub on solar panel maintenance and lifespan gathers it all.

Export in the dark months

Any spare power you send to the grid can earn payment. Ofgem says suppliers set their own Smart Export Guarantee rates, but those rates must be above zero. In winter you will export little, so the rate matters less then. Our guide to the Smart Export Guarantee explains how to compare tariffs, and our hub on batteries and export covers storage choices.

The bottom line

Solar panels do work in winter. They make less, and the gap is large, but they still earn their keep over a full year. Treat winter as the weak season and plan around it. For the basics of how the panels turn light into power, see how solar panels work.

Sources

Common questions

Do solar panels work when it is cloudy?

Yes, they still make power from daylight, but less than in bright sun. The yearly estimates from tools such as PVGIS already allow for typical UK cloud. Expect output to drop further on heavy overcast days.

How much do solar panels make in December?

PVGIS estimates about 133 kWh in December for a 4 kWp south-facing system near Birmingham. That is under 30% of what the same system makes in June. Output is lower in Scotland and for east or west roofs.

Is it worth having solar panels if I use most power in winter?

It can be, because summer output is high and can cover your daytime use then. However, the winter share of your bill will stay mostly unchanged. A battery or a time-of-use tariff can help with the evenings.

Should I clear snow off my solar panels?

Do not climb on a roof to do it, because it is dangerous. Ask your installer for safe advice instead. Output is low in snowy weather anyway.

Do solar panels need sunshine or just light?

They work from daylight, so direct sun is not essential. Direct sun gives the best output. Cloud and low winter sun cut it.