Sunset in Plymouth
If you have solar panels, or you’re thinking about them, that raises a fair question: Do they still work in winter, and what happens to your savings once it’s dark by teatime?
The short answer is yes they do still work, although they produce less electricity. Here’s what to expect between now and February, and how a battery helps as the evenings draw in.
The clock change
Does Changing the Clocks Affect Your Solar Panels?
Not directly. Turning the clocks back doesn’t alter how much sunlight reaches your roof; it simply moves an hour of daylight from the evening to the morning.
What does change is when you need power. Early evening is when most homes cook, run the washing machine and switch on the lights. From 25 October, more of that happens after sunset, once your panels have stopped generating.
So the clock change is a good moment to look at how you use the electricity your system makes.
Winter output
Do Solar Panels Work in Winter?
Yes. Solar panels run on daylight, not heat, so they produce electricity whenever it’s light, even on dull, grey days. In fact, panels are slightly more efficient when it’s chilly.
The catch is the short days and the low winter sun. Less light reaches the panels, and what does arrive comes in at a shallow angle.
Here’s what a south-facing system typically generates in the darkest and brightest months, based on UK averages from the EU’s PVGIS solar model:
| Month | Output per kWp | 4 kWp system |
|---|---|---|
| December | 29 kWh | About 116 kWh |
| January | 33 kWh | About 132 kWh |
| May | 119 kWh | About 476 kWh |
| June | 117 kWh | About 468 kWh |
Source: PVGIS estimates averaged across UK postcodes, compiled by Solar by Postcode.
4 kWp system, per day
In other words, a panel makes roughly a quarter as much in December as it does in June. For a 4 kWp system, that’s just under 4 kWh a day in December (116 kWh ÷ 31 days), compared with more than 15 kWh a day in June (468 kWh ÷ 30 days).
Battery storage
Why a Battery Earns Its Keep After the Clocks Change
Without a battery, any electricity you don’t use as it’s generated goes to the grid. You’re paid for it through the Smart Export Guarantee, at around 12p per kWh from the SEG-licensed supplier you choose. That’s well below the 26.32p per kWh you’d pay under Ofgem’s October-December price cap to buy power back in the evening.
A battery keeps that daytime surplus for later instead. MCS benchmark figures suggest a typical home uses about 26% of its own solar electricity without a battery, and about 62% with one.
In mid-winter, there may be little spare solar to store. That’s when a battery pays its way differently: it can charge overnight on a cheap off-peak tariff, then run the house through the busy early evening.
Find out more about home battery storage, or read about the popular Tesla Powerwall 3, which we’re certified to install.
“Panels don’t switch off in winter; there’s just less daylight to work with. Over the darker months, a battery and the right tariff do a lot of the heavy lifting to help keep your savings up.”
The new year
What January’s Price Cap Could Mean
Electricity is likely to cost more in the new year. Energy consultancy Cornwall Insight forecasts a 16% rise in the price cap in January, taking a typical household’s annual bill to £1,999. Ofgem will confirm the real figure by 25 November.
The dearer each unit from the grid, the more every kWh from your panels or battery is worth. Our article on Martin Lewis’s warning about January bills looks at what’s behind the increase.
This winter
What to Expect From Your Panels This Winter
- Lower readings in your app. Output usually bottoms out in December and starts to recover through January and February. A dip at this time of year is normal, not a fault.
- Leaves and debris. Autumn foliage can collect along the lower edge of panels. If anything is still sitting there after a few weeks of wet weather, it’s worth getting the panels cleaned.
- A sudden drop. If output falls sharply on a bright day compared with a similar day the week before, get in touch, as that’s more likely to point to a problem than to any seasonal differences.
- Your energy plan. If you have a battery, see whether a time-of-use tariff with cheap overnight rates suits you. Our article on flexible pricing with solar and storage explains how these deals work.
Installing now
Is Winter a Good Time to Install Solar?
Yes. Panels fitted now start generating straight away, and you’ll be ready for the much longer days of spring.
Book a free survey or call us on 01752 916 013.
Your questions answered
Winter Solar FAQs
Do solar panels work on cloudy days?
Yes. They generate from diffuse daylight even when the sky is overcast, although output is much lower than on a bright day.
Do solar panels work in the snow?
Only once it clears. On a pitched roof, light snow often slides off or melts fairly quickly, but panels covered in it produce very little. Never climb up to clear them yourself.
Do solar panels still save money in winter?
Yes, but less than in summer. In December, a south-facing system makes about a quarter of its June output, so most of your yearly savings come between spring and autumn.