Do Solar Panels Work in Winter?

Yes, solar panels work in winter, but a UK system generates roughly a quarter as much in the winter quarters as it does in the summer ones. The Department for Energy Security and Net Zero publishes the exact figure every quarter. UK solar ran at a load factor of 4.45% in October to December 2025 and 5.65% in January to March 2026, against 19.13% in April to June 2025. Same panels, same country, about four times the output.

That gap is not a reason to skip solar. It is a reason to buy it on the annual number rather than a sunny-afternoon demonstration, and to understand which months your savings actually come from. This page uses DESNZ quarterly statistics, Met Office 30-year sunshine averages and Energy Saving Trust guidance, all fetched on the day of writing.

How much less do solar panels generate in winter in the UK?

About a quarter of what they generate in summer, measured across the whole UK fleet. The cleanest way to see it is the load factor, which is the electricity actually generated as a percentage of what the installed capacity could have produced running flat out. DESNZ publishes it quarterly in Energy Trends table 6.1, most recently on 30 July 2026 with new data for January to March 2026.

Add those four quarters together and the UK fleet produced 20,172 GWh over the year to March 2026. The two winter quarters, October to March, account for 4,822 GWh of it, which is 24%. So roughly three quarters of a year's solar electricity in this country arrives in the six months from April to September.

One caveat in our favour, and it is worth stating. Installed solar capacity grew steadily through that year, from 20,371 MW at the end of June 2025 to 22,349 MW at the end of March 2026, so the winter quarters had more panels working than the summer ones did. The real seasonal swing for a fixed system is therefore slightly wider than 24% against 76%. DESNZ also notes that these load factors are calculated on installed capacity at the beginning and end of each quarter, which can be influenced by when new capacity came online.

These figures cover everything from field-scale solar farms to houses. DESNZ states that the solar PV data includes installations on the Feed-in Tariff scheme plus sub-50kW installations registered with the Microgeneration Certification Scheme, which is where domestic rooftops sit.

Why winter output falls: it is the daylight, not the cold

Panels need light, not warmth, so the thing that flattens winter generation is short, dim, overcast days rather than low temperatures. The Energy Saving Trust lists three reasons on its solar fact check page, updated 16 July 2026: "the days are shorter", "it's more likely to be cloudy" and "the sunlight isn't as intense".

The Met Office 30-year averages put numbers on that. At Heathrow, on the 1991 to 2020 averaging period, December records 54.96 hours of sunshine against 217.81 hours in July. That is the whole story of the seasonal swing in two numbers, and it maps almost exactly onto the DESNZ load factors.

Cold itself is not the enemy. A bright, frosty January morning is good generating weather, and the same Met Office data shows Heathrow averaging 26.99 days of air frost a year without that stopping anything. What panels cannot do is manufacture daylight that is not there. The Energy Saving Trust also confirms the point people most often get wrong about cloudy days: panels "still generate electricity on cloudy days" because they absorb both visible light and "wavelengths that can pass through clouds". Less, but not nothing.

The north-south gap is a summer gap, not a winter one

In January there is barely any difference in sunshine between the south of England and the north east of Scotland. The gap opens up in summer. This is the finding most solar pages miss, and it comes straight from Met Office long-term averages for two official stations.

January at Dyce averages 60.45 hours of sunshine against Heathrow's 61.09. That is a difference of well under an hour across the whole month. July is where the two part company, 162.44 hours against 217.81.

The practical reading for a homeowner in Scotland or the north of England: your winter is not meaningfully worse than a Londoner's winter. Your summer is. That is consistent with the Energy Saving Trust payback table, which is built on July 2026 fuel prices and includes export payments, and puts payback at 9 years in London, 9 to 10 in Aberystwyth, 10 to 11 in Manchester and 11 to 12 in Stirling. A gap, but a narrow one. Northern Ireland is not in that table yet, and the Energy Saving Trust says it will be added in the next update.

Winter is when solar saves you the most per unit

You generate least in winter and every unit you do generate is worth more to you, because in winter almost all of it gets used in the house instead of exported. This is the part of the seasonal story that actually affects your bill.

The maths is set by the gap between what you pay for electricity and what you are paid for exporting it. Under the Ofgem price cap for 1 July to 30 September 2026, a typical direct debit customer in England, Scotland and Wales pays 26.11p per kWh with a 57.19p daily standing charge, giving a cap of £1,862 a year. Exported units earn far less. The Energy Saving Trust says you will "typically get around 12p for every unit that you don't use yourself" through the Smart Export Guarantee, and notes that you would normally buy electricity for more than twice that.

So a unit you use is worth roughly twice a unit you export. In June, with the house empty and the array producing hard, a lot of your generation goes to the grid at the lower rate. In December, output is small enough and demand high enough that nearly all of it is swallowed by the house at the moment it is made. Your December generation is smaller, but almost none of it is sold cheap.

That is also why a system sized purely on summer surplus can disappoint. If you are working through whether the whole thing stacks up, our guide to whether solar panels are worth it in the UK works through the self-consumption maths in full, and what solar panels cost in the UK covers the price side.

What winter means for a battery

A battery sized on your summer surplus will spend much of the winter part-empty, because there is often no surplus to store. Storage shifts solar electricity from the middle of the day to the evening. It does not create any.

With the fleet running at a 4.45% load factor in October to December against 19.13% in April to June, the daily surplus that fills a battery in July frequently does not exist in December. The Energy Saving Trust puts battery storage at around £5,000 to £8,000, so it is worth being clear-eyed about which months it earns that back in. Batteries do have a genuine winter job, but it is usually a different one: paired with a time-of-use tariff, a battery can be charged from the grid at cheap overnight rates and discharged at peak times, which works in December as well as June. Our solar battery storage guide covers the costs and payback in detail.

One winter-specific point worth asking about at quote stage. The Energy Saving Trust is explicit that solar panels typically cannot power your home during a power cut, and that a battery normally will not either "unless additional equipment and configuration is included in the installation". Storm season is exactly when people assume otherwise. If backup power in an outage matters to you, it has to be specified and paid for.

How to buy solar without being sold a summer

Four things to insist on, all of which cut through seasonal sales talk:

• Ask for the estimated annual generation in kWh, in writing. A single day's peak output, or a figure from a bright afternoon site visit, tells you nothing about February.
• Check the orientation assumption. The Energy Saving Trust says an east or west facing system tends to get around 15 to 20% less energy than one facing directly south, and it does not recommend north facing roofs at all.
• Ask what proportion of the generation the quote assumes you will use yourself. That single assumption drives the savings figure more than anything else, because used units are worth roughly twice exported ones.
• Get more than one quote. The Energy Saving Trust recommends quotes from at least three MCS-certified installers. Our guide on choosing an MCS-certified installer covers what else should be in writing.

If you are still at the sizing stage, start with how many solar panels you need and cost by system size. For the long view, how long solar panels last covers the 25 winters the panels are expected to see.