How do solar panels work? The ultimate guide to solar panels

20 August 2020 | OVO Energy

how do solar panels work

Whether it’s a rooftop panel or a 500-hectare photovoltaic plant, solar is fast becoming the cheapest source of energy globally. Yes, that giant glowing ball we occasionally see in the UK skies can do a lot more for humanity than just put us in a good mood!

With the cost of solar energy plummeting in recent years, alongside some major improvements to the science, there’s no denying that solar is going mainstream.

Read on to find out about how solar power works, the economic advantages of solar energy, and how to get solar panels installed in your home.

What are solar panels?

Solar panels are groups of photovoltaic (PV) cells that turn sunlight into electricity. Solar is a plentiful, renewable source of energy – and solar energy even works well in the grey old UK, because solar panels don’t need direct sunlight to function. Thankfully for us!

Whilst PV is the most common type of solar panel, there are also other types of solar power.  For example, solar thermal panels use sunlight to heat water flowing through the panels, which can then be used to heat your home.  

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How do solar panels (PV) cells work?

A solar panel’s photovoltaic cells are sandwiched layers of semi-conducting materials, usually made of silicon. Each layer has different electronic properties, which energise when hit by photons from sunlight, to create an electric field. This is known as the photoelectric effect, and this creates the current needed to produce electricity.

One solar panel typically consists of around 30 cells (those familiar-looking blue squares you often see in a solar panel). It can generate around 300W of power in full sunlight, depending on brightness, size of panel and other things like temperature. 

The panels generate a direct current of electricity, which then passes through an inverter to convert it into an alternating current. This charge can then be funnelled into the National Grid, or used by any home or business with solar panels.

The benefits of solar power

The brilliant thing about solar is that it can create a lot of cheap power close to where it’s being used.

Solar panels are also easy to install, making them suitable for all sorts of locations. From rooftop panels in city centres to large countryside solar farms, they’re highly scalable and adaptable.

From an environmental point of view, solar’s amazing because it releases no harmful carbon – and it just goes on and on. In fact, a typical home solar PV system could save around 1.3 to 1.6 tonnes of carbon per year (depending where you live in the UK1). 

In the south of England, a 3.5kWp system can generate around 3,700 kilowatt hours of electricity a year. That's the same amount of electricity as it takes to turn the London Eye 49 times! And in Scotland, the very same 3.5kWp system can generate about 2,850 kilowatt hours of electricity a year – which is the same amount of electricity as it takes to turn the Falkirk Wheel 1,900 times2!

Once they’ve been installed, solar panels need little to no maintenance – just occasional cleaning to keep them clear of dirt and debris.

Solar panels also don’t create any noise pollution while they’re generating electricity. And because they’re made of silicon, they’re super-safe and non-toxic too. The benefits just keep stacking up!

Interested about renewable energy? Learn more about the pros and cons of each type of renewable energy

How much do solar panels cost?

There’s no denying that solar panels are a long-term investment – so the initial costs can seem somewhat high. But with the price of solar being 70% cheaper today than in previous years3, it’s much more affordable lately. Plus, given that electricity and gas bills could go up over time, a solar panel system will help to insulate you from those rising costs. Not to mention that it potentially adds value to the price of your home!

While there are currently few (if any) government incentives and schemes, the price of a solar system is continuing to fall. These days, an average solar set-up will cost somewhere between £2,500 and £8,000 (including installation4), depending on the number of panels and the size of your roof.

Are solar panels right for me?

Solar power panels

Most UK homes are suitable for solar – but the best homes are ones with south-facing roofs with a pitch of 30-40 degrees. We wouldn’t suggest putting solar panels on a north-facing roof, but you might find that an east or west-facing roof still works well (although you’ll probably generate around 25% less energy). 

Your roof also needs to be strong enough to house the panels – and you’ll need space in your loft (or similar) to house the inverter. Getting a qualified installer to check your house before making any decision is a must!

The other good news is that most homes don’t need planning permission to install solar panels. But if you have a flat roof, or live in a conservation area, check with your local council before going ahead. 

How much will solar panels save me?

The exact amount you could save depends on several things, including the size of your solar installation and the way you use the energy you generate.

Calculations can be a bit tricky – but let’s assume that the average UK home has a 3.5kW installation on its roof. This will cost around £4,8005 (although expect to pay more if you have any ‘tricky’ installation issues or want a bigger system). We estimate that a 3.5kW panel in southern England will return about £290 to your hip pocket in the first year, and deliver an approximate 5% rate of return over the 25 year lifetime of the installation. 

The amount you save will depend on where you live in the UK (i.e. the amount of sun your home gets), how much generated electricity your home uses, and how much you pay for electricity. Many suppliers offer calculators to help you do the maths.  Just remember, solar panels last for 25 to 30 years, so they’re a great investment!

Typically, the more electricity the system can generate, the more it costs – but the more it could also save. Larger systems are usually more cost-effective than smaller systems, generating up to 4kWp (enough to meet the energy needs of a family of 3 to 4).

How to make money from solar energy

While the government’s previous Feed-in Tariff is no longer available, you can still make money from any unused electricity by selling it back to the National Grid.

There are 2 ways to do that. The first is via a battery, which will store the unused electricity and helps you to run off-grid, depending on the amount you collect and use.

The second is the government’s Smart Export Guarantee, which means that energy suppliers will compete to give households the best price for their excess electricity. Homeowners will still see a long-term payment and faster return on their investments. Find out more about the Smart Export Guarantee.

Are solar panels worth it?

The solar subsidy may have fallen – but so has the cost of the technology. And with an average system generating around 3,700 kWh a year, that works out at about 92,500 kWh of electricity generated by solar over its lifetime.

That fact alone makes solar panels very worthwhile, even just from a financial perspective. Add to that the many environmental benefits to be gained – from helping to lower emissions and tackle air pollution, to reducing your home’s carbon footprint – and it’s clear that solar is a smart, sustainable choice to help supercharge your journey to carbon zero.

How to install solar panels

As with any big investment, it pays to get several quotes from different providers before making any decisions. We recommend that you check the company you choose is a certified installer. Find out more about the Microgeneration Certification scheme

It’s a good idea to go with a strongly recommended provider. is a good place to search for provider reviews. 

Learn even more about solar energy here

Want to join the renewable energy revolution and fight climate change? Find out more about our energy plans.

Check our range of plans and see how much you could save now.


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