The ultimate guide to solar panels

Last updated: 15 October 2020

In this guide you’ll find answers to the following questions:

  • What are the different types of solar panels?

  • How do solar panels work?

  • What factors affect the performance of solar panels?

  • How much do solar panels cost?

  • Are solar panels worth it?

What are solar panels? 

Solar panels, also known as PV panels, are systems that convert the sun’s energy into electricity. If you harvest this free energy, you can save money on your electricity bills.

The panels are made from a thin layer of semi-conducting material that’s placed between sheets of polymer resin and glass. Then, after exposure to sunlight (including indirect sunlight on cloudy days), the semi-conducting material will become energised, producing electricity. 

What are the different types of solar panels? 

There are three main types of solar panels in the UK, all of which differ in terms of price and efficiency:

Panel typeTypical efficiency*Description
Monocrystalline17-22% One of the most efficient types of panel, as they use extremely pure silicon.
Polycrystalline15-17% Features a distinctive blue look – are cheaper and less efficient than monocrystalline panels.
Thin film10-13% Portable and flexible, it’s the cheapest type of solar panel, and the least efficient, so rarely found in residential housing.

*As a percentage of energy received. Higher is better.

Other types of panel are also being developed to try and increase efficiency, reduce material cost, boost longevity of solar systems, and provide a more aesthetically pleasing appearance. These include:

  • Bifacial

Capable of generating electricity from the back of the panel as well as the front using a reflector.

  • Concentrated PV cell

Uses lenses or curved mirrors to focus the sunlight to increase efficiency.

  • Solar tiles

Made from monocrystalline or thin film, designed to be more aesthetic, but are slightly less efficient than traditional cells.

  • Transparent solar panels

Designed to capture the energy from non-visible wavelengths only, while allowing visible light to pass through. This makes them technically capable of covering any surface so, despite their likely low efficiency (11% estimated), they could become widespread.

How do solar panels work? 

A solar system contains numerous elements: each panel of solar cells is connected to an inverter that converts the electricity from DC to AC, and a generation meter to record the amount of electricity being generated for the purpose of selling it back to the grid.

Solar cells have two layers. The top layer has been treated so that it has too many atoms, while the bottom layer has too few. When light hits the top layer of the panel, the electrons will begin moving to the bottom layer. As they move together in the same direction, electricity is generated. 

The inverter is need because the electricity generated by solar panels is direct current (DC), while the electricity used in buildings is alternating current (AC), so the electricity must be converted before it can enter the electricity grid – whether to directly power your home or be sold back as excess to the grid.

What’s the difference between kWp and kWh?

Solar panel systems are rated in kWp – kilowatts peak. This means the maximum performance rating under ideal conditions – typically noon on a sunny day. Solar panels rated at 3 kWp will rarely (if ever) generate anywhere near 3 kWp.

The actual amount of electricity generated by solar panels is measured in kWh – kilowatt hours. In perfect conditions (see next question), your panels should generate the following amount of electricity:

System sizeNumber of panelsRoof spaceAnnual generation
1 kWp48 m2850 kWh
2 kWp814 m21,700 kWh
3 kWp1221 m22,550 kWh
4 kWp1628 m2 3,800 kWh

What factors affect the performance of solar panels?

The following factors all determine how well your panels will actually perform compared to the ideal presented to you by solar salespersons:

  • Direction your roof is facing: due south is the perfect setting.

  • Angle of roof: 30-50 degrees is considered ideal.

  • Type of panels: see above.

  • How much sun your site receives per year: the further south you are, the better. Similarly, drier areas (like the south-east) will improve performance further.

What are the advantages of solar panels?

There are several advantages associated with solar panels, including: 

  • Reduce your carbon footprint

Because solar electricity doesn’t release CO2, solar panels are a great way to cut your carbon footprint. 

  • Off-grid availability

If you live in a remote area, then solar panels offer a flexible way to generate energy even when there’s no connection to the grid. Note, you’ll need batteries to use solar in this way.

  • Energy that pays for itself

Once you’ve paid to have the panels put up, you don’t need to pay anything for your solar energy. 

  • Access to renewable energy

You’re not going to run out of solar energy, so after installation, you’ve got access to a great source of sustainable, renewable electricity

  • Minimal maintenance

While you may need to clean your solar panels a few times a year and occasionally replace parts (particularly older inverters), solar panels do not require much maintenance and tend to be extremely durable, lasting 25-30 years. 

What are the drawbacks of solar panels? 

There are three principal disadvantages associated with social panels:

  • High installation costs

The cost of having solar panels installed in the first place can be off-putting. It’s usually thousands of pounds, so if you can’t afford to pay, you may not be able to access solar energy. Replacing certain components – specifically the inverter – can run into the thousands of pounds.

  • Suitability of your property

You’ll need a roof large enough to accommodate the panels you require to produce enough power (typically 4 panels per 1kWp of electricity). Your roof should also be south-facing (or as close to it as possible) to capture the maximum amount of electricity over the widest period during the day.

  • Inconsistent power generation

While solar panels will still generate energy on cloudy days, the weather can influence their efficiency, so you’ll never know how much electricity you’ll generate from one day to the next. Typically, your panels will generate most electricity during the longer, summer months when there tends to be more periods of direct sunlight. During the shorter, winter days, you’ll find less electricity is produced, so your panels will offset less of your overall energy consumption.

  • No use at night

Solar panels produce no electricity at night, so unless you have a battery system to store the power generated during daylight hours, you may find savings minimal if no one’s at home during working hours.

How can I get UK solar panels fitted? 

If you want to have solar panels installed, follow these steps: 

Consider whether your home is a good fit for solar panels

Unless you have enough room on your roof to generate enough energy to power your home, it is unlikely that solar panels will be the best choice. You can still install them to generate a smaller amount of energy, but this won’t be enough to cover all your energy costs. You should also factor into your decision that a south-facing roof is best for generating solar energy. 

Check to see if planning permission is required

Next, you’ll need to contact your local council to see whether planning permission is necessary for installing solar panels. Unless your panels are over a certain size, you live in a listed building, or you live in a conservation area or World Heritage site, you shouldn’t need to get planning permission. 

Find a solar panel installation company

Once you’ve got everything set up and you’re sure that your home is a good fit for solar panels, it’s time to find someone who can handle the installation process. After finding a company in your local area, request a site visit along with a technical survey. You can also ask them for the addresses of other installations in your local area so that you can see examples of previous work. Ideally, you should opt for an installer who is Microgeneration Certification Scheme-certified (check this out on the MCS website).

Of course, if you’re installing DIY solar panels in the UK, then you’ll need to do the installation yourself. DIY solar panel kits should contain the information you need to carry out the installation, while there are also plenty of guides on the internet that you can follow. 

What is the Feed-in Tariff? 

The Feed-in Tariffs (FiT) scheme is a programme designed to promote renewable and low-carbon energy generation. Essentially, it’s a payment you will receive from the government for generating your own electricity. However, it’s important to note that the scheme has not accepted new applicants since 31st March 2019, so if you’re not already on a Feed-in tariff, then you won’t be able to take advantage. 

How much do solar panels cost? 

Expect to pay anywhere from £1,500-£3,000 (1 kWp system) to £6,000-£8,000 (4 kWp system) for a system installed by a qualified and accredited company. However, there are also DIY solar panels in the UK that can lower your installation costs. These DIY kits can cost between £600 and £4,500, giving you everything you need to complete the installation on your own. 

Once installed, a standard 4 kWp solar panel system can generate around 3,800 kWh of electricity per year. This could save you hundreds of pounds per year, and within a decade, you can expect to have offset the initial installation cost. From then on, your solar panels will start making you a profit. 

It’s also worth remembering that solar panels in the UK can add value to your home by making it more appealing to prospective buyers. Plus, solar panels may raise your home’s energy efficiency rating, which is often a significant advantage for people who are looking to sell their home. You may also become eligible for the Renewable Heat Incentive, where you can receive payments from the government for generating your own renewable heating with systems like solar panels.

Are solar panels worth it? 

Ultimately, solar panels can be an excellent investment if you’re able to pay the hefty up-front costs of installation. By exporting excess electricity to the grid, not only will you save money on your bills (particularly if you’re at home all day), you’ll also generate some revenue you can use to offset your bills further. Savings on a 4 kWp system in the south of Britain can be between £300-£390 a year.

If you can afford them, investing in a battery storage system releases the potential for even more savings over the lifetime of your solar panel system, eventually resulting in a profit.

Plus, by adding value to your home, you can see additional returns from your solar panels in other areas. But it’s not all about cost. Solar panels are an excellent source of renewable energy that will help you cut your carbon footprint quickly and effectively.

Read more:

Green Energy Comparison | Switch To A Green Energy Deal

Switch to a green energy tariff. Compare green energy deals and switch to a better deal today, it's quick and easy!

Read More
Man looking at Energy Performance Certificate on tablet

Energy performance certificates

Everything you need to know about Energy Performance Certificates including what they are, how to get them and how to improve your EPC rating.

Read More
Houses using the Renewable Heat Incentive

What is the Renewable Heat Incentive?

Everything you need to know about the Renewable Heat Incentive scheme - what is RHI? And how do you apply?

Read More

Written by

Published on Wed 13 Nov 2019 11.34 GMT