Do Solar Panels Work When It’s Cloudy?

Is Solar Really Worth The Investment With The UK Weather?

When you think of solar panels, you’ll correctly do the basic math and the more sunshine, the more electricity you can generate. Does this mean that when the sun is obscured, then you can say goodbye to your solar power? What happens if one little cloud rolls in front of the sun? Can you expect your TV to go dark, the fridge to go silent, and the Wi-Fi to switch off?

And, for UK residents this is a very real concern. We live in a country synonymous with grey weather. Ask anyone overseas what they think of British weather and there’s a high chance they’ll say rainy and cloudy, not sunny blue skies. So, the question is: do solar panels work on cloudy or rainy days? Do solar panels work at night? And is solar even a good idea for UK homeowners?

How Do Solar Panels Work?

To answer those questions, we need to do a very basic course in how solar panels work.  

When talking about solar panels in this blog post, we mean solar PV panels, not solar thermal panels. While solar thermal panels trap heat from the sun (which can then be used to warm water and heat your home), PV panels convert light from the sun into electricity.  

What is PV? PV is short for photovoltaic, which literally means light and voltage. A solar panel has multiple PV cells made of semiconductors like silicon, laminated to glass. When particles of light (photons) strike a PV cell they knock electrons free from atoms and generate electricity.  

Solar panels are designed to absorb as much sunlight as possible and convert it into DC (direct current) power. Houses mostly run on AC (alternating current), and so the DC is converted through an inverter to be used directly in the home, put back into the grid, or stored for conversion later.   

Do Solar Panels Work On Cloudy Days?

We’re not in short supply of cloudy days here in the UK, so knowing if your solar panel will still generate electricity when the sky is grey is one of the most frequently asked questions for new customers. And, the answer is, yes. In the same way you can get sunburn on a cloudy day, your solar panels will continue to generate electricity on a cloudy or rainy day.  

However, they are of course more effective when there are no clouds, and it is a sunny day. Estimates vary, but, on a cloudy day you can expect to continue to generate from 10% – 25% of the electricity you would generate on a sunny day. Even though that might not sound a lot, it’s still saving money and helping reduce carbon emissions. And a little bit of rain can be a good thing, because it washes the panel (more often than you might) and so helps keep the panel at optimum solar energy generating potential.

Do Solar Panels Work In Winter?

Chilly temps, shorter daylight hours, and even snow might make you think that solar is a dead loss in winter. And while the shorter daylight hours can have an impact, it’s good to remember that solar PV panels use light, not heat to produce electricity. So, providing the angle of your panels doesn’t allow too much buildup of snow (which can reduce their lifespan and slow their ability to generate electricity), those cloudless blue-sky days in winter can be great for generating electricity during daylight hours.  

Do Solar Panels Work At Night?

The short answer is no. In fact, that’s also the long answer. When there is no sun, the solar panel won’t be able to generate electricity for your home. In the same way when you put your finger over the little solar panel on your school calculator it turned off the display, when the light is gone, so is the ability of the panel to generate electricity.  

So, how does solar help if you want to watch Netflix after the sun has gone down? Well, that’s where solar storage and the ‘grid’ comes in. Most homes with a solar connection remain connected to the grid, and when their system produces excess electricity, it feeds it back into the main electricity grid. In some cases, this results in compensation from the electricity supplier through the Smart Export Guarantee, and usefully for you at night this means you’re still connected to a power supply. No, you aren’t using solar power, but you’re still able to use powered devices like normal after dark.  

The second option is getting a battery system to store the solar power you make during the day and using that when the sun has gone away. The only factor to consider is the cost of a battery storage system can double the cost of your solar setup, so it’s worth chatting to the experts at Trusted Energy Solutions to see if it’s a cash savvy idea for your home. 

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