Once solar panels are installed, all the electricity you get from them is free.

The government give you money for having them – so the more electricity you generate, the more you earn.

The initial outlay can seem expensive but that’s because solar panels are a long-term investment.

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Solar panels are great. Once you’ve had them installed, the electricity they make is free, renewable and environmentally-friendly. In fact, it actually earns you money.

Solar panels can appear expensive upfront and you might be wondering whether you should get them. This guide will give you everything you need to know, including how they work, the pros and cons, rough costs and the leading solar panel manufacturers.

What's in This Guide to Solar Panels?

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Solar Panels: The Basics

There are 2 types of solar panel: photovoltaic (PV) panels and thermal panels. The former generate electricity; the latter just heat water. This page is about photovoltaic panels.

Photovoltaic means that the panels produce electricity when they are exposed to light. This electricity provides power for your home.

But unlike with mains electricity, the supply from your solar panels isn’t unlimited; they only have a certain capacity. That’s not a problem, because you’ll still be connected to the national grid, so if you need more electricity than they’re providing, your home will automatically just start drawing electricity from the grid instead. This makes no practical difference – you won’t even notice it happening. But you’ll have to pay for electricity from the grid, so solar panels won’t do away with your electricity bills, they’ll just reduce them.

On the flip side, though, if you don’t need all the electricity the panels produce, it isn’t wasted – it’s sent to the national grid for someone else to use. And you get paid for this.

Even better, in England, Scotland and Wales, the government also pays you just to have solar panels. Your energy company pays you, tax free, for all the energy you produce for the first 20 years of having solar panels, even if you use it yourself. So you’re paid for all the energy you generate, and if you then send some of it back to the grid, you’re paid for it again.

The payments you get for generating electricity are called the generation tariff, and the payments you get for selling the electricity back are called the export tariff. Together, they’re known as the government Feed-in Tariff. Northern Ireland has a slightly different system, called the Northern Ireland Renewables Obligation Certificates.

Still want more information? This video provides you with a short run-down of everything you need to know about solar panels.

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How Do Solar Panels Work?

A solar panel works by what’s known as the photoelectric effect – the fact that some materials emit electrons when light is shone on them.

Inside a solar cell are 2 thin layers of silicon crystal. Both layers have been interfered with slightly so that their atoms are unstable. The atoms on the top layer all have 1 electron too many, and the atoms on the bottom layer all have too few electrons. Atoms don’t like having the wrong number of electrons, so the top ones are all keen to get rid of their extra electrons and the bottom ones are all keen to acquire some.

However, the electrons need to be exposed to sunlight to give them the energy to get moving. And when electrons move, they create an electric current. At this stage, the electricity will be DC (direct current) – the kind of electricity you get in batteries – so you’ll have a device called an inverter, which turns it into AC (alternating current) electricity, the kind that comes off the mains and powers your home.

But this is Britain… it’s always raining!

As long as there’s daylight, solar panels will work; the sun doesn’t need to be beating down. In fact, we’ve created a guide on the best conditions for generating solar energy.

The panels won’t, of course, work as well on a cloudy day, and they won’t work when it’s dark, so you’ll use electricity from the grid at night.

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What are the Advantages and Disadvantages of Solar Panels?

Advantages

✔ Money saving. The electricity from your solar panels is free, plus you get paid through the feed-in tariff. If you’re wondering how much you could save with solar panels, check out our guide on whether they’re a good investment.

✔ Renewable energy. Sunlight will never run out, unlike fossil fuels, which are still our main source of energy.

✔ No pollution. Solar energy doesn’t generate carbon dioxide or contribute to global warming. According to the Energy Saving Trust, a typical home solar power system could save around 1.5 to 2 tonnes of carbon each year.

✔ Easy to look after. Solar panels are easy to install and require almost no maintenance as they have no moving parts. You may need to clean them from time to time, or the rain may do that job for you. See, Britain is perfect for solar panels after all!

✔ Off-grid energy. If your home isn’t connected to the national grid, solar panels are a straightforward way to generate your own electricity.

Disadvantages

✘ High initial cost. Solar panels can cost several thousand pounds upfront – see our table below.

✘ Weather dependent. They’re less efficient in cloudy weather and don’t work at night, which also means they won’t provide as much electricity in the winter, when there is less daylight.

✘ Physical appearance. Solar panels will alter the appearance of your house and this is not to everyone’s taste.

You can read more about the advantages and disadvantages of installing solar panels on our pros and cons page.

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Are Solar Panels Suitable for Your Home?

First, you need to have a roof – and the bigger and more exposed to the sun it is, the better. Solar panels work best on south-facing roofs; they work reasonably well on east and west-facing roofs. But on a roof that is north-facing or very much in the shade, they may not get enough sunlight to make the cost of installing them worthwhile. For most homes, solar is a viable option.

They can be installed in blocks of flats, but you’ll need to find out whose permission you need as even if you own the flat, you may not own the freehold.

You don't usually need planning permission, unless you live in a conservation area, listed building or World Heritage Site, or the panels would be visible from the roadside. In those cases, you should check with your district or borough council. You should also let your home insurer and your mortgage company know that you plan to install solar panels.

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What Size Solar Panels Do You Need?

The power of solar panels is measured in kWp: kilowatts peak. The kilowatt is a measure of electrical power, so the kWp figure tells you how much power the panels can produce when they are operating at their maximum capacity. This will be when it is sunniest.

A typical domestic system will be between 1.5kWp and 4kWp. Obviously, the more powerful your system, the more electricity it will generate, and the more expensive it will be to install (although this won’t increase exponentially, because double the panels aren’t double the work to install). Once you get over 4kWp, the Feed-in Tariff rate isn’t usually as good. As a rough guide, for each kilowatt, you’ll need about 7 square metres of roof space. You can read more about what size panels you need for your home here.

The amount of electricity the system generates in a year is measured in kilowatt hours (kWh). Each kWp should generate around 800 to 850kWh per year. So based on the figures in the previous paragraph, a typical domestic system would be likely to generate between 1,200kWh and 3,200kWh per year.

The Energy Savings Trust estimates that an average 3-bedroom family home in the UK uses around 3,000 kWh of electricity per year.

Your solar panels will come with a meter, which will show you exactly how much electricity they’re producing and how much you’re selling back to the grid.

Check out this guide if you’re still unsure as to how many solar panels you'll need for your home.

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How Much Do Solar Panels Cost in the UK?

Solar panels are not cheap – but they’re not meant to be. They’re a long-term investment which, once you’ve had them installed, will cut your electricity bills and reduce your carbon footprint every day for several decades.

They can cost anywhere between £1,500 and £8,000. As a rough guide you can expect to pay:

Size	Output	Cost
1kW solar panels	750 to 850kWh per year	£1,500 to £3,000
2kW solar panels	1,700kWh per year	£3,000 to £5,000
3kW solar panels	2,550kWh per year	£4,000 to £6,000
4kW solar panels	3,400kWh per year	£6,000 to £8,000

If this looks like a very wide price range, it’s because so many variables will affect the cost: the type of panel, the supplier, the size of your home and your family. You can get a much more accurate estimate by getting a quote from one of the trusted suppliers we recommend – or have a look at our solar panels prices page.

Can You Get a Grant to Install Solar Panels?

The Government doesn’t offer grants, because it remunerates you through the Feed-in Tariff. However, there is some financial help available through the government’s ECO scheme. The Scottish Government also offers some interest-free loans for homeowners who want to install renewable energy systems.

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How Much Can You Save with Solar Panels?

At the time of writing (April 2018), solar panel owners are paid 4.01p per kWh for the solar energy they generate (the generation tariff), and 5.03p per kWh for the energy they sell back to the grid (the export tariff). So if you have a 3kW system, that’s £100 a year you’re getting paid for doing absolutely nothing – plus whatever you earn from the export tariff.

If you live in England, Scotland or Wales, these rates apply if your home has an EPC energy efficiency rating of D or above. If not, you won’t earn so much from the feed-in tariff.

84% of homeowners we surveyed save up to 50% on their monthly energy bills with their solar panels*

*Based on a survey we conducted in January 2018 of 390 UK homeowners with solar panels.

This is how much we’d expect you to save each year with solar panels (based on a monthly electricity bill of £50):

Size	Cost	Annual Payment from Generation Tariff	Annual Payment from Export Tariff	Annual Electricity Bill Savings	Total Annual Savings
1kW solar panels	£1,500 to £3,000	£36	£33	£23	£92
2kW solar panels	£3,000 to £5,000	£73	£65	£46	£183
3kW solar panels	£4,000 to £6,000	£109	£72	£68	£249
4kW solar panels	£6,000 to £8,000	£145	£91	£72	£308

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How Long do Solar Panels Last For?

Solar panels often have a 25-year guarantee, but should last for longer than that – probably between 35 and 50 years. The inverter will likely need replacing after 10 to 15 years, or maybe sooner; inverters cost from around £500.

You can read more about the life expectancy of solar panels here.

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Types of Solar Panel

All photovoltaic products work the same way, but it’s worth understanding the difference between the different types of solar panels:

Monocrystalline solar cells are the most compact and efficient, but also the most expensive. They generally have a longer lifespan than polycrystalline cells and thin film cells, and their efficiency tends to be less affected by higher temperatures.

Polycrystalline solar cells are cheaper than monocrystalline, but less efficient and compact. Monocrystalline and polycrystalline panels are the most widely used and widely tested.

Thin-film solar panels are less efficient still, and cheaper still. They are very thin – hence the name – but so large that they are not always suitable for houses. They also tend to have a shorter lifespan than crystalline cells. However, they are better at working efficiently in cloudy and dim conditions.

Solar tiles actually replace the tiles on your roof, instead of being placed on top of it, and are designed to fit in with your roof’s appearance. Solar roof tiles are more expensive, and less efficient than panels because they are fairly small, but they may be suitable for listed buildings where other options aren’t as they are less noticeable.

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What are Solar Batteries?

A solar battery allows you to store the electricity (energy) generated by your solar panels so you can use it overnight or on cloudy days, instead of paying for electricity from the grid. Plus, if there’s a power cut, you’ve still got electricity.

These aren’t little batteries like you have in your remote control; they can be as big as a fridge, so you’ll need enough space in your house. They are likely to cost between £1,000 and £6,000, plus installation, and their storage capacity can be anywhere from 1kWh to 14kWh. You should never let the battery run to empty as it can be damaged, so always look at the usable capacity rather than the total capacity when deciding how big a battery you need.

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Which are the Best Solar Panel Brands?

There isn’t that much to choose between the big manufacturers, as most of the panels are made in a similar way. However, it is very important that your installer is accredited by the Microgeneration Certificate Scheme for renewable energy, or MCS, or you won’t be eligible for the Feed-in Tariff.

Yingli: This Chinese company was set up in 1998 and is one of the biggest solar manufacturers in the world. To date, Yingli has sold more than 85 million solar panels in more than 90 countries.

Canadian Solar: As the name suggests, it’s based in Canada, and is another of the world’s biggest solar companies, having sold more than 70 million panels since its foundation in 2001. In Which?’s customer satisfaction survey in June 2017, Canadian Solar achieved the highest score out of 7 solar manufacturers, with 85%. It also scored 5 stars in a Which? audit of solar power factories in 2015.

Suntech: Headquartered in China and founded in 2001, Suntech has sold more than 25 million solar panels in 80 countries. It also received 5 stars in the Which? audit in 2015; it came bottom of the 7 brands in the 2017 customer survey, but its satisfaction score was still 75%.

Sharp: A Japanese company, Sharp has been working on solar cells since way back in 1959 and has always been a pioneer in the field. The firm has been selling domestic panels since 2004 but has also made solar cells for everything from calculators and lighthouses to satellites for Japanese national projects. Sharp came fifth out of 7 brands in Which?’s 2017 customer survey, with a score of 80%, and scored 5 stars in Which?’s factory audit.

Solarworld: This German manufacturer achieved 5 stars in the 2015 Which? factory audit and a customer satisfaction score of 77% in 2017, placing it sixth out of 7 brands. All of Solarworld's products are monocrystalline cells.

Panasonic: This Japanese firm was founded in 1918 and has been producing solar technology since the 1970s; it has now sold 3 million panels just in Europe. Panasonic got the joint second-best customer score in Which?’s 2017 survey, with a satisfaction rating of 83%. Its factory wasn’t audited, but Which? says: “trusted installers we’ve spoken to told us they would recommend Panasonic panels.” In March 2016, Panasonic set the record for efficiency of a commercial-sized solar panel. Sanyo, which is owned by Panasonic, came fourth in Which?’s 2017 customer survey, achieving a score of 81%.

LG: This Korean company has been a pioneer of electronics in the country since its inception in 1958 and has been working on solar technology since 1985. The company achieved the joint second-best customer satisfaction score of 83% in Which?’s 2017 survey; its factory wasn’t audited.

Which? also audited the Aleo Solar, ATERSA, Bisol, Finale 24, Hanwha Q Cells, JA Solar, Kyocera, LDK Solar, Open Renewable and Solarwatt factories. All received either a 4 or 5-star rating, and Which? said: “these are all brands you should consider when choosing solar panels.”

You can read more about the best solar panels and how much you should expect to pay.

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