What is solar energy and how does it work?

Thinking about solar panels for your home, or just interested in learning more about solar power? In this article, we explain how solar panels work, the differences between the two main types of solar panels, and how solar energy is generated – even on those grey, overcast days.

How do solar panels work?

Most of us know the basic idea – solar panels work by turning sunlight into electricity. That’s what photovoltaic (PV) solar panels do, anyway.

They’re by far the most common type of solar panel, but not the only one. We’ll talk more about the other types of panels later.

But first, let’s go into a bit more detail about all the clever science and technology of PV panels, and how they turn sunlight into solar power.

What are solar panels made of?

Solar panels are made up of several smaller parts called solar cells. These cells only produce small amounts of solar energy on their own, but chain them together and those small amounts start adding up.

So, when we talk about a solar ‘panel,’ what we mean is a sturdy frame, a few dozen cells wired together, and a sheet of non-reflective glass over the top to make sure as much light reaches the cells as possible.

So, what are solar cells made of?

You can make solar cells from a variety of materials. But the solar panels you might see day to day will almost always be made from silicon. Two layers of slightly different types of silicon to be exact.

How do solar panels turn sunlight into electricity?

Sunlight hits the cells

The silicon in the top layer gets hot and bothered by this. Or in slightly more scientific terms, the electrons in the silicon atoms get knocked out of their usual, comfortable resting places by the sun’s energy.

The electrons want to cool off

They want a nice, shaded spot to settle down in again. The place for this? The bottom layer of silicon.

The electrons set off for the shade

Luckily for the flustered electrons, we’ve built a corridor connecting the two silicon layers, which they head down in order to escape the sun.

This creates a current

The corridor we’ve just mentioned is essentially a wire. And the electrons moving through it to get to the bottom layer? That’s an electric current.

The electric current becomes electricity

The direct electric current made by the moving electrons is converted into the alternating current we use in our homes. Voila, electricity!

The other silicon layer gets crowded

Like a seaside town in summer, the bottom silicon layer soon gets overcrowded with electrons trying to escape the sun. Struggling to find a restful spot, some of the electrons circle back to the top layer to try their luck there, and the process starts all over again.

The science of solar power is admittedly a little more complicated. But the general gist is that as long as there’s daylight, electrons are constantly moving around, searching for shade. And that movement creates electricity. This means, even in deepest darkest winter your panels can still generate electricity.

What is the difference between PV and thermal solar panels?

Most people have a clear idea of what solar panels are, but did you know there are two main types that do very different things?

Photovoltaic (PV) panels

When someone uses the phrase ‘solar panels,’ they almost always mean PV panels that generate solar power These are by far the most common panels seen on UK homes. And the ones we offer here at Hive.

Solar thermal panels

Instead of generating electricity, thermal panels are designed to harness solar energy to heat water. These solar panels work in a much simpler way, where sunlight literally heats a liquid mixture within the panels, like a radiator in reverse. The heat that’s captured is then stored in a hot water tank for later.

Hybrid panels

These combine the two types, sandwiching PV and thermal panels together. When paired like this, they are actually more efficient than each type of panel on its own. But as you might expect, these double-duty panels are expensive. It can also be a bit of a struggle to find anyone qualified to install these complicated systems.

Which is right for you?

If your main goal is to lower your electricity bills and run your home on renewable solar energy, PV solar panels are likely the better fit.

If you want to reduce your water heating costs specifically, that’s when solar thermal panels might be the system worth considering.

Is solar energy renewable?

This one’s easy. Yes, absolutely! Solar energy is often seen as one of the cleanest and most abundant renewable energy sources we have. As long as the sun shines, we’ll never run out of it.

Using solar power at home means you're using fewer fossil fuels, cutting your carbon emissions and lowering your impact on the planet, especially if you pair your panels with battery storage.

On top of the environmental benefits of solar power, there’s a financial bonus too. Solar panels can bring down your electricity bills. And through the Smart Export Guarantee (SEG), you can even earn money by selling the excess electricity you don’t use back to the grid. You’ll need an SEG tariff to do that, which our friends at British Gas can take care of for you.

What is a solar generator?

A solar generator is a complete system that combines solar panels with a battery in a single, standalone and often portable unit.

They are essentially a big, rechargeable battery, so they can lend themselves to many uses. From the recreational, like providing solar power for an extended camping trip; to the more practical, like as an emergency backup during a power cut.

Do you need one for your home?

Portability is the main selling point of solar generators, which is why most UK households don’t need one. Instead, you’ll get more benefit from pairing your home’s solar energy system with permanent battery storage, which our third-party installers can also put in for you.

The solar energy you create but don’t immediately use will charge these batteries. They can save you even more money on your energy bills because at night, for example, you’ll first use the solar power stored in your batteries before paying to use electricity from the grid.

In addition, if you ever experience a power cut, you might not even notice – because some solar batteries can provide independent backup power. And because it’s all connected at home, everything will just work, as opposed to having to manually plug your fridge into a portable solar generator.

How is solar power generated in different weather conditions?

Now this is a question we get asked a lot: Do solar panels still work in the UK’s often cloudy weather? The good news is yes, they do.

On cloudy days

Even when you can’t see the sun for the clouds, light is still getting through. It might be overcast, but it’s not dark. So your solar panels will carry on generating electricity, just less than they would on a clear day.

Even in the winter, solar panels will contribute around 8% of your year’s solar energy generation – so they’ll still contribute to cutting down your energy bills.¹

In rainy weather

Heavy rain and heavy cloud cover typically go hand in hand. And water on your panels will also stop some of the sun’s energy getting through. But rain isn’t necessary a bad thing. A good shower can wash off dust, and the cleaner they are, the more efficient solar panels work.

Getting the most out of your solar system

The position and angle of your solar panels can have a big impact on how much solar energy they generate. Installing panels on an unshaded, south-facing roof is ideal, but that doesn’t mean fitting them elsewhere won’t still be a worthwhile investment and save you money on your electricity bills.

There are lots of little differences in climate up and down the UK. Want to know about where in the country is the best place to get panels? Check out our guide to the UK’s solar sweet spots.

Looking to install solar panels?

We’re the experts, so we’d be happy to help with that. Get started with a personalised, free home survey from one of our third-party installers, where they’ll find the best solar power set-up for you and your home, then put together a fixed-price quote.²

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¹ For a property with a 3.2 kW south-facing array in London, Summer typically accounts for 43% of your yearly solar energy generation with Spring 32%, Autumn 17%, and Winter 8%. Season generation depends on location, roof orientation, and solar array size.

² Subject to no specification changes.