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

11 January 2022 | OVO Energy

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 over the last few years, alongside some major improvements to the science behind them, there’s no denying that solar is going mainstream1. But how do solar panels work?

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.  

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

There are plenty of advantages to solar energy. If you’re considering solar panels, here are just some of the benefits you could enjoy:

  • Affordable power: Solar energy can create a lot of cheap power close to where it’s being used.
  • Easy installation for all sorts of locations: From rooftop panels in city centres to large countryside solar farms, they’re highly scalable and adaptable.
  • No harmful carbon: From an environmental point of view, solar’s amazing because it releases no harmful carbon.
  • Easy maintenance: Once they’ve been installed, they just need occasional cleaning to keep them clear of dirt and debris.
  • No noise pollution: Solar panels also don’t create any noise while they’re generating electricity. And because they’re made of silicon, they’re super-safe and non-toxic too.

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

Solar panel costs

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 years2, 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. With the current energy crisis for example, solar PV becomes even more attractive, with rapidly reducing Return On Investment. 

Not to mention that it potentially adds value to the price of your home!

At the moment, there isn’t an up front government grant available to incentivise solar power. But those who generate their own energy can get the Smart Export Guarantee (SEG). This pays out money for all the energy which is generated and exported to the grid. Each energy supplier mandated to offer it have a rate, up to 5p/kWh. But you must have a smart meter to be eligible for it.  

How much energy does a solar panel produce? 

Solar power panels

Once installed, 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 UK3). 

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 times4.

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 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:

  • where you live in the UK (the amount of sun your home gets) 
  • how much generated electricity your home uses 
  • 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, with some newer models even lasting as long as 50 years6 – 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 through home battery storage which can store unused electricity and help you to run off-grid, depending on the amount you collect and use.

The second is the government’s Smart Export Guarantee (SEG). This means that energy suppliers 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 might 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.

Are solar panels right for me?

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 support 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 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. Yougen.co.uk 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.

Solar Panel FAQs

Solar panels are a big investment, so it’s important to know they will stand the test of time. The lifetime of a solar panel is around 25-30 years, with the latest models boasting a lifetime of between 40-50 years if taken good care of. Of course, as your solar panels get older, there might be a drop-off in performance. But don’t worry, as many come with warranties that guarantee performance won’t drop below 80% efficiency7

The main material in solar panels is silicone, thanks to its affordability, long lifespan and ease of use. Silicone is the semiconductor material in around 95% of all solar panels, including the most common monocrystalline, polycrystalline and thin-film designs. The main difference in these types of solar panels is their efficiency and affordability. 

Other materials in solar panels typically include an anti-reflective glass coating, metal, wiring and a plastic/polymer frame to mount the panels on a rooftop or secure them to the ground8.

Solar panels can still produce energy on overcast days. However, they are at their most efficient when in direct sunlight. So you’ll want to carefully think about where your solar panels will be installed to make sure you get the most from them9.

When looked after well, your solar panels can last for decades. To keep them in tip top condition, wipe them down with a soft brush, ideally when they are wet, to remove any grime. Avoid using harsh chemicals or abrasive sponges which can damage the panels. Long handled tools provide easier access, allowing you to clean them while on the ground. 

Clean your solar panels on a weekly or monthly basis for best results. This will prevent a build up of dirt and ensure they work efficiently10.

You won’t need planning permission to install solar panels on your home, unless you live in a listed building or in a conservation area. If that’s the case, you’ll need to get permission from your Local Planning Authority first. Solar panels are also subject to building regulations, so you’ll still need a certified installer to complete some checks before installation.

A report by Solar Energy UK found that solar panels could increase the value of a typical home by at least £1,800. They might also make your home more attractive to future homeowners. That said, with the high initial cost of installation, the main financial benefit in the short-term will be the savings on your energy costs11.

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