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How solar panels work

Let’s face it, the UK isn’t a Mediterranean country – so can we realistically get enough electricity from sunshine to power our homes? You might be surprised at how efficient solar panels can be, especially in rainy Britain. Here’s a look at how solar panels work.

Let’s face it, the UK isn’t a Mediterranean country – so can we realistically get enough electricity from sunshine to power our homes? You might be surprised at how efficient solar panels can be, especially in rainy Britain. Here’s a look at how solar panels work.

Written by
Dan Tremain
Energy and business energy expert
Reviewed by
Rebecca Goodman
Insurance expert
Last Updated
10 MAY 2024
4 min read
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How do solar panels work?

In its simplest form, a solar panel sits on the roof of your home and draws energy from the sun. It then turns that energy into electricity, which can be used to power your home.

Solar panels are made of photovoltaic cells (PV) that are sandwiched between a semi-conducting material, such as silicon. When sunlight hits the solar panels, the PV cells absorb the light and convert it into direct current (DC) electricity. This is then passed through an inverter box that converts it into alternating current (AC) electricity. The electricity collected can then be funnelled to the National Grid or used to power your home.

Does it need to be sunny for solar panels to work?

Not necessarily. If there’s enough daylight for you to see, there’s enough light for solar panels to work. This means that even on cold and cloudy days, your solar panels will be able to generate electricity.

It makes sense that the stronger the sunlight, the more efficient your solar panels will be. That’s why they’re able to produce more electricity in summer. But it’s the light from the sun that makes the solar panels work – not heat. In fact, extreme heat or cold can actually make them less efficient.

Here in the UK, we don’t usually experience extreme temperatures. But we can expect around eight hours of daylight in the winter and around 16 hours of daylight in summer, which means we’re quite well set up for solar power. It can be a little more or less than this depending on where you live. For example, if you live on the south coast you’re probably going to have more sunlight than those living in Newcastle.

How efficient are solar panels?

Solar panel efficiency depends on a number of factors. If you want to install solar panels, you’ll need to consider:

  • Which direction your roof faces – a south-facing roof will have more access to direct sunlight, while east and west-facing roofs will be around 15-20% less efficient. Solar isn’t recommended for north-facing roofs.

  • The amount of shade covering your roof – for example, because of surrounding trees, chimneys or other buildings.

  • Roof space – your roof needs to be big enough to accommodate the right size and number of panels for your energy needs.

  • Roof angle – your installer should be able to help advise you if your roof is suitable. 

  • The type of PV cells – different types can produce more or less energy, depending on their size, thickness and purity. The purer types are generally more efficient, so tend to cost more.

  • The number of solar panels you have installed.

Facts about solar panels

  • Solar energy is the most abundant source of energy on the planet.

  • China leads the way in global solar energy with nearly 400 gigawatt (GW) capacity.

  • There are over 1.4 million PV systems installed throughout the UK.

  • According to government figures for 2023, the largest contribution to new renewable capacity was in solar PV – at 1.1 GW it was the highest for almost six years and continues to be driven by small-scale installations. 

  • Residential solar panels are now more than 60% cheaper than they were in 2010.

  • Some solar panels are now guaranteed for 40 years.

  • You can become more energy independent if you install a battery to store unused energy generated during the day to use at night – but this will add to the cost of any installation. You can also export energy stored in your battery back to the grid if you don’t need it.

How much do solar panels cost?

The average PV system size provides around 3.5kWp of electricity and costs around £7,000. This sort of system will typically take up around 20m² roof area.

If you decide to add a battery to the system to store unused power, this may add several thousand pounds more to your costs. But this could mean further reductions in your bills.

What are the advantages of solar panels?

  • A clean and green source of renewable energy

  • Could help save money on your electricity bills

  • A lower carbon footprint

  • Solar panels are silent – no noise pollution

  • Earn money by selling unused energy back to the grid through the Smart Export Guarantee scheme

  • Extremely low maintenance.

What are the disadvantages of solar panels?

  • Initial cost of installation can be expensive

  • Efficiency is dependent on the weather and the direction your roof faces

  • You need a fair amount of roof space

  • Many of the schemes that made solar panels more attractive have now ended

  • Not all roofs are suitable for solar panels.

If you’re interested in learning more about solar panels and the potential savings you could make, take a look at our guide to solar panels for the home.

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