Do solar panels work in winter?

If you're considering making the jump to solar energy, you might be one of many people thinking that solar panels only work in the summer months.

Well, luckily for those of us living in the UK, where sunshine can often be in limited supply, this actually isn’t true.

Yes, even though solar panels do need the sun’s energy in order to generate renewable electricity, they don’t need to be in direct sunlight in order to work. 

In this guide, we'll walk you through how solar panels work in winter and on particularly cloudy or rainy days to help you make the most of your solar system all year round.

How do solar panels work?

Solar panels are made up of smaller units called solar PV (or photovoltaic) cells. These cells are designed to convert sunlight directly into electricity.

When sunlight hits the surface of a solar panel, it excites the electrons in the cells, causing them to move and create an electric current.

While it's true that winter days are shorter and sunlight might be weaker due to cloud cover or snow, solar panels can still produce electricity as long as they receive some sunlight.

Read our full blog post for a comprehensive breakdown of how solar panel systems work.

Do solar panels work in winter?

In short, yes! Solar panels do work in winter.

They’re able to operate in all four seasons of the year thanks to the fact that they can still capture the sun’s solar energy even when it isn’t at its most intense or direct.

Think about it this way; unless you’re living inside the arctic circle and your home is plunged into months of constant darkness during the winter, the sun will still be providing light from morning to evening. So, even though it might not be sun tanning weather, your solar panels will be harnessing the sun’s rays and converting solar energy into electrical energy. 

What’s more, thanks to recent technological advancements, modern solar panels are engineered using systems of lenses and mirrors to capture different parts of the solar spectrum and maximise energy generation.

Now, there is one caveat to this for UK homeowners. Since the days are shorter in the winter months and the sun is less intense than it is in summer, your solar panels won’t operate quite as efficiently in December compared with in July. 

Not a deal-breaker by any means, but just something to bear in mind when exploring solar installation, how many solar panels you might need for your property and whether you should consider combining solar power with a supporting energy source.

How does the weather affect solar panel performance?

The weather can sometimes impact the efficiency of solar panels, but this isn’t always in a negative way. Let’s take a closer look at the weather conditions that can actually improve the energy generating potential of your solar panel system.

Rain

Light to medium rainfall doesn't significantly impact solar panel performance. In fact, rain can actually help clean the panels and remove any accumulated dust or debris that might be blocking light, thus improving their efficiency.

Snow

During snowy periods, your solar panels will still work to convert solar energy to electricity.

If solar panels are completely covered in a layer of snow, it can pose a challenge to electricity generation. Luckily, experienced installers will know to tilt your solar panels at around 30 to 45 degrees, which means snow will slide off instead of building up in large quantities.

Additionally, the dark glass that covers solar panels holds residual heat and works to melt snow before it becomes detrimental to their panel’s performance.

Clouds

Contrary to popular belief, modern solar panels actually work well in cloudy conditions. They might not be quite as efficient as when the weather is sunny but they’ll still generate electricity when it’s overcast. 

Think about it in terms of your own relationship with the sun. You don’t have to be lying on a beach to get sunburnt; you can get sunburn just from being outside on a cloudy day if the UV index is high enough.

Plus, scientists have discovered that some cloud cover can actually work in favour of your solar panels! Referring to what’s known as the “edge of cloud” effect, experts show how the wispy edges of clouds can act as magnifying glasses, catching the sun’s rays and intensifying them before they hit your solar panels.

Temperature

Many people are surprised to learn that solar panels are actually more efficient in colder conditions since there is greater movement of electrons at lower temperatures.

In fact, solar panel systems can experience some pretty serious problems in hotter regions. If the internal components within the panels overheat, hot spots and micro-cracks can form, resulting in reduced efficiency. 

Ultimately, we should be thinking about solar panels as the electrical appliances that they are. Gadgets and gizmos don’t tend to do so well when they overheat (which is why computers have built-in cooling fans), meaning lower ambient temperatures are actually ideal working conditions for solar cells.

How much energy do solar panels generate in winter?

If British weather is anything to go by, we know that no two winters or locations are alike. One year, we’ll see clear-blue skies and crisp, cold days then the next will bring milder temperatures and freak snowstorms. 

In practice, what this means for solar panel users is that there won’t ever be an ultra-accurate guarantee of how much energy a solar system will generate in the winter. 

What we can do, though, is use the performance data provided by manufacturers to calculate approximations for how many kilowatt hours our solar cells will provide.

Solar panels all have something that those in the know refer to as a temperate coefficient pMax. In layman’s terms, this is just the percentage measure of how much a solar panel’s efficiency is affected by temperature changes. 

As standard, solar panels are power tested in controlled conditions at 25°C. If, for example, a panel has a pMax of -0.5%, it means that its efficiency will reduce by 0.5% for every 1°C rise or fall in the ambient temperature. 

Temperature isn’t the only factor that influences solar panel output in winter, though. A range of variables can come together to impact how much energy your solar panels will be able to generate. In use cases cited by the Energy Saving Trust, the electricity generation of some panels from November to February was only 10% of what it was in the summer.

This should be taken with a good pinch of salt. Even though energy production might be lower in the winter, it never falls to zero. What’s more, you can store surplus energy generated during the summer in solar batteries to make sure you have a far more consistent supply year-round. 

Solar installation with BOXT

At BOXT, we’re working to make the home heating industry fairer, greener and more affordable for UK homeowners, one rooftop at a time.

When you choose to buy a domestic solar panel system through BOXT, you can relax knowing our expert team is taking care of everything. We design solar solutions according to your home and heating requirements, not those of your next-door neighbours or national averages. 

For a personalised plan equipped to meet your needs, simply answer a few questions about your property using our simple online tool.