Do solar panels work in winter and on cloudy days?

These are two of the most common questions we hear from homeowners thinking about switching to solar energy in the UK. Many people believe that once the summer sun disappears, their solar panels become little more than expensive roof decoration.

We’re here to tell you that this simply isn't true. The answer to both questions is yes!

While your solar energy output will naturally be lower than the peak production you see during long, bright summer days, modern solar panels remain effective even when it’s cloudy and cold. The key to understanding this is knowing that solar panels generate electricity from daylight, not just direct sunlight or heat.

Solar energy is a year-round investment, and we’re here to show you why.

How solar panels perform in winter and on cloudy days.

Understanding how your solar panels work in the UK's famously changeable weather is straightforward. It all comes down to the technology within the panels themselves, specifically, the photovoltaic (PV) cells.

Daylight vs. direct sunlight: How solar panels generate power.

The science is simple: PV cells generate electricity when light hits them, causing electrons to move. This means that as long as it's daylight, your panels are producing power. They don't need intense heat or clear skies to get to work.

Do solar panels work on cloudy days?

Yes, they do, and quite well too! Modern solar panels are designed to capture not just direct light, but also diffused light, the light that filters through the cloud cover.

While a glorious, sunny day will always result in greater output, even the low light of a gloomy day can generate a reasonable amount of power. Think of it this way: your panels are always on duty, working hard to capture every available photon.

The impact of shorter days in winter conditions.

Solar panels operate throughout all four seasons. However, you will naturally produce less energy in the depths of winter. This is mainly because the days are shorter, and the sun is lower in the sky, resulting in fewer total hours of effective daylight.

To put this into perspective, we estimate that UK panels produce only 10% to 25% of their total annual energy during the entire winter period (December, January, and February).1 But that 10-25% is still energy you don't have to buy from the grid!

Why cold temperatures can actually increase solar panel efficiency.

This is often the most surprising part of the solar equation: cold weather doesn't stop your panels, it can actually make them more efficient!

The thermal coefficient is a key metric here. The standard efficiency rating for a solar panel is typically measured at a cell temperature of 25°C. Efficiency change is approximately 0.5% per degree below 25°C.2

This describes the rate at which a solar panel's performance decreases as its temperature rises above 25°C. Conversely, its performance often increases when the temperature drops below this point.

When panels get hot (like in peak summer), the heat increases the electrical resistance within the PV cells. This resistance lowers the voltage output and, therefore, the overall efficiency. In cold weather, resistance is lower, allowing the electrons to flow more freely.

So, the answer to the question "Can it be too cold for solar panels?" is no. While cold often comes with shorter, cloudier days, the ambient temperature itself helps the technology work at its peak electrical capability.

The low-down on solar panels and snow.

A solar panel that is completely covered in thick snow cannot absorb light, meaning it won't produce electricity. However, the good news is that for most correctly mounted panels in the UK:

Is your home ready for year-round solar success?

The performance of your solar panels in winter is also heavily influenced by the quality and design of the installation itself.

The right roof angle and tilt for winter performance.

Because the sun is lower in the sky in winter, the angle (or tilt) at which your panels are installed matters.

An experienced, certified installer, like our MCS-accredited professionals, will assess your specific roof angle and orientation to determine the best possible placement for maximum year-round generation. While they'll aim for peak summer performance, they'll also ensure your panels are well-positioned to capture the lower winter sun.

The importance of a well-designed solar PV system size.

Your installer will assess your household's energy needs (how much electricity you use) and size the system accordingly. A larger household with high usage might benefit from more panels to offset the lower generation in winter. A correctly sized system ensures that even with the natural reduction in output during colder months, you are still generating a meaningful proportion of the energy you need.

Find out more about how solar panels work.

Real-world impact on your energy bills.

The true value of solar panels is not just about sunny summer days, it's about the combined year-round savings and income they generate.

Solar energy – a year-round investment.

Solar panels are a highly viable and beneficial energy solution for homes across the UK. The myths about panels being useless in winter or on cloudy days are just that, myths. The combination of cold-weather efficiency, smart battery storage, and lucrative SEG and our Next Smart Saver tariff makes solar a powerful, money-saving, and greener choice every single month of the year.

Ready to take control of your energy bills and contribute to a cleaner, brighter future?