Do solar panels work on cloudy days? A guide to the best conditions

Even if you don’t know a lot about solar panels, you’re probably aware that they convert light to electricity you can use to power your home. Naturally this raises the question: do solar panels need direct sunlight? This may especially be a concern in the UK, where sunny weather isn’t guaranteed.

Do solar panels need direct sunlight in order to work?

The short answer is no. The longer answer is that solar panels use direct and indirect sunlight because both types carry photons. Photons are particles of solar energy and they are what the photovoltaic cells (PV cells) in the panels convert into electricity.

Even on cloudy days, enough daylight will be able to pass through the clouds and reach your solar panels for them to work. How much energy they produce will depend on how heavy the cloud cover is. Clouds which sit at a high altitude tend to be thinner and may even magnify the sunlight.

Modern solar panels are built with concentrators, which are there to maximise the light which reaches them. These concentrators use Fresnel lenses to take the rays of sunlight and bend them so they focus towards each solar cell. This focus makes the PV cells more efficient.

That said, it’s true that the best conditions for solar panels are strong, direct sunlight, as it generates more electricity. But they still work without it, and can even work using only indirect sunlight.

Do solar panels work in winter?

Yes. Heat doesn’t affect how much electricity is generated, so if daylight is present then the solar panels will work. Winter rain won’t make a difference, but the amount of cloud cover will — the heavier the clouds, the lower the output. If you wish to learn more about this topic, we invite you to read our complete article about solar panel efficiency in winter conditions.

Do solar panels work with snow on them?

It depends on how heavy the snowfall is. A light layer of snow isn’t a problem, as sunlight can still get through to the panels, but a thick layer would block the light out. Fortunately, the snow doesn’t tend to stick around for too long as the panels sit at an angle and can get warm enough to melt it away.

The benefits of solar batteries

Solar batteries allow you to bank any energy that’s produced but not used during the day. The solar panels convert light into electricity as normal, but any excess energy is sent to a battery storage unit and stored there until it’s ready to be used. This ensures you have energy to power your home when it gets dark, during a power outage, or during times when persistent heavy cloud cover reduces the amount of light that reaches the panels. Any energy not used can be sold back to the grid.

The best direction and angle for solar panels

The best direction for solar panels to face in the UK is the south, because they’ll have the most exposure to the sun and therefore the highest chance of converting light into energy. East and west-facing buildings can also get a good amount of sunlight. Solar panels facing east will get the most sunlight in the morning, when the sun rises, while solar panels facing west will get the most sunlight later in the day, before the sun sets.

The best angle for solar panels to sit at is between 30 and 45 degrees, as this maximises the amount of sunlight they’ll be exposed to.