Do solar panels work in winter?

Wondering if solar panels can still work their magic as the cold nights draw in and cosy knitwear makes its appearance?

The good news is that solar panels are designed to work in all seasons, including winter. Despite shorter days and chillier temperatures, they can still generate electricity - even if they aren’t necessarily at their peak performance.

Let's explore how solar panels can make the most of winter daylight, even during the coldest months of the year.

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Do solar panels actually work in the winter?

As solar photovoltaic (PV) panels need daylight rather than heat, they can still generate electricity during the frosty season – although they might not be as effective because of a combination of factors associated with winter:

• Winter days are shorter, meaning less daylight for solar panels - so energy production is lower compared to gloriously long summer days
• The sun is lower in the sky during the UK’s (and other northern hemisphere countries’) winter months, resulting in less direct sunlight reaching the solar panels
• Things like snow, leftover autumn leaves and other debris on the panels can block daylight and reduce their efficiency even further.
• If the PV panels aren’t properly sealed, moisture from damp and icy days can seep into the cells and cause damage.

But even with these challenges, solar panels can still be a viable option for sustainable energy all year round. After all, winter doesn't stop solar panels from producing a decent amount of electricity on clear, sunny days. And with the high upfront cost of solar panels, you'd be right to expect them to keep working in all weather.

Does cold weather affect solar panel output?

Cold weather can affect solar panel output, but not in the way you might think. Like most electronics, solar panels work best in cooler temperatures.

Although it seems odd for a device that likes to spend its time basking in sunlight, the electrical resistance of a PV cell decreases in colder weather, which means better electron flow and improved efficiency.

But while cool temperatures can improve the efficiency of solar panels, temperature extremes can do more damage than good - whether that’s very cold or very hot weather.

Can solar panels get too cold to work?

Although some solar panels can become less efficient if the temperature drops below their optimum operating temperature (typically between 20°C and 25°C), quality panels are designed to withstand a temperature range between -30°C and 85°C.

Thankfully, our milder UK winters are unlikely to ever reach those temperatures.

With that being said, extended freezing temperatures could lead to temperature-related degradation that causes slight physical changes in the panel materials. And over time, this can lead to permanent damage.

To learn more about solar, check out our full rundown of the top 17 solar panel facts.

Solar panel output winter vs summer in the UK

According to figures from the National Energy Action (NEA) charity, the difference between peak summer and peak winter can be staggering, with findings showing that solar panels can generate up to eight times more electricity in the summer.

Taking a 5 kW (kilowatt) solar PV system as an example, typically in the UK it might produce around 450-480 kWh (kilowatt-hours) of electricity in July compared to around 50-60 kWh in December.

These are just rough estimates, and the actual output will vary depending on factors including how the panels are positioned, what the weather is like during those months, and where the solar PV system is.

Solar PV panel technology has also advanced, making modern panels better at generating energy in low-light conditions and reducing seasonal variations in output.

Solar panel output by month in the UK

As mentioned above, the output of solar PV panels in the UK can vary significantly between winter and summer because of differences in daylight hours and sun angles.

The following graph shows how a solar system’s energy output can change from month to month.

This chart is based on the same typical four-bedroom family home in Essex using 4,000 kWh of electricity each year, with a 6 kWp solar panel system and a 5.2 kWh battery. The system produces nearly 25 kWh of electricity per day in May and July, whereas it produces only 4.9 kWh per day in December.

Summer vs winter solar panel output in the UK

Broadly speaking, a solar panel system in the UK will produce about 70% of its total output in spring and summer (March to August), with the remaining 30% coming in autumn and winter (September to February).

The chart below should give you a rough idea of how productive your solar panel system will be across the four seasons (ranging from around 11% in winter to almost 38% in summer).

Solar panel output by season

Do you need to buy electricity from the grid during winter?

In the vast majority of cases, UK households with a solar-plus-battery system will need to purchase additional electricity from the grid during the winter months. Even with a top quality system placed on a south-facing roof in the south of England with 0% shading, it would be rare to see a property not need the grid throughout the whole winter. 

However, note that this is usually only additional electricity, i.e. just ‘topping up’. In the winter, solar panels still provide something, just not everything you’ll need. Look at the graph above - you can see that there’s still generation happening in November, December, January and February, but it’s falling about 50-60% short of the household’s needs. 

By adding a battery to a solar panel system, you can also make sure that you’re using any solar-generated electricity in the winter evenings if you weren’t around in the daytime. 

And remember, you can reduce your energy load in the winter by adding insulation, using energy-efficient appliances, and reducing your overall energy consumption.

Can solar panels work in snow?

Solar PV panels won't be able to generate much power if it's snowing heavily and there's no sunlight - but they can still convert winter sun into electricity, even when covered with a thin layer of snow.

Once snow or ice builds up and blocks the sunlight, however, it becomes a problem. So it's best to clear heavy snow off quickly to preserve maximum efficiency, although you should never do this if it means climbing up onto your roof. This is dangerous and should only be done by a qualified solar panel technician.

How to keep snow off your solar panels

The first step is to make sure a professional installer fits your solar PV panels at an angle that allows snow and rain to slide off naturally, rather than letting them accumulate on the surface.

As recently as September 2023, scientists in the US have invented a new “self-cleaning” solar panel strip that automatically melts snow without interfering with the panel itself. Even though this ingenious solution isn’t yet ready for the consumer market, it has the potential to make solar panel maintenance in the winter a breeze - which is great news for homeowners.

To keep your solar panels performing at their best, gently brush off the snow with a soft brush or by using a specially designed snow removal tool. Avoid using sharp or abrasive tools, as these can scratch or damage the panels. Once again: don’t do this if it means going up onto your roof, as this should only be performed by a qualified solar panel technician.

Summary

Despite the shorter days, solar panels can still work efficiently during winter in the UK, especially on clear days.

We've seen that cold weather can boost efficiency, while snow can be a bit of a hassle - still, with well-positioned panels and proper care, homeowners can take full advantage of the winter sunshine.

So while you may not generate as much electricity, solar panels can still be a worthwhile investment even during the colder months.

Solar panels in winter: FAQs