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Solar energy

Solar panels are becoming increasingly popular across London, allowing you to generate your own renewable electricity and heat from the sun. Find out whether solar panels could work for you.

Energy from the sun can be used to heat water and power homes, and more people than ever are looking into it for their homes, especially with recent energy price hikes.

In 2019, the production of electricity from renewables in the UK overtook fossil fuels for the first time – reaching a record 85% share on 17 August that year.

While much of this low carbon energy is produced by solar (and wind) farms, it’s possible to generate your own solar energy on a much smaller scale. Here’s what you need to know about generating your own electricity and heat from the sun.

Solar PV

Solar photovoltaic (PV) panels are becoming increasingly popular, with many buildings across the UK sporting visible solar panels on their rooftops.

They work by capturing energy from the sun and converting it into electricity, which you can then use in your home – from powering your lighting and appliances to charging up your electric vehicle.

If you want to reduce your energy bills and cut your carbon footprint, then installing solar PV panels at home could be a great choice.

How do solar panels work?

Solar panels are built from layers of cells, which are usually made of silicon (although they could use other semi-conducting materials). When sunlight shines on these cells, it creates a flow of electricity.

Importantly, solar panels don’t need direct sunlight to work, so they can still generate electricity for your home on cloudy days. However, the stronger the sun is shining, the more electricity you’ll get.

A typical solar panel installation has around 15 individual panels. Each system comes with an inverter too, which converts direct current (DC) electricity produced by the panels into alternating current (AC) electricity – which you can then use to power the appliances in your home.

If you don’t need all the electricity produced by your solar panels, for example if you generate more than you can use or spend a large portion of your day out of the house (so aren’t using any appliances), you can export any excess electricity to the grid or store it using a battery system.

Will solar panels work for my home?

There are several questions you need to consider before deciding if solar panels are suitable for your home and lifestyle.

Space is a key consideration. The average solar panel system needs around 25m2 of roof space that ideally faces South. East or West facing roofs can still be appropriate, however if your roof faces North, we wouldn’t recommend getting solar panels.

If your roof is shaded by any nearby trees, buildings or chimneys, this will also negatively impact the performance of your solar panels.

Solar panels usually don’t require planning permission, however if you live in a listed building, conservation area or national park, you should check with your local planning office in case additional restrictions apply to your property.

Cost is also something you’ll need to consider. While the cost varies depending on where you live, your installer and the type of panels you want, as a guide you can expect to pay around £6,500 for a typical 4.2kWp system.

What happens to the electricity I don’t use at home?

There will probably be times when the electricity your solar panels generate is more than you can use (or store, if you have a battery) at home. This excess electricity can be exported to the grid, so someone else can use it.

If you want to be paid for the electricity you export, you need to make sure you’ve signed up for an export payment scheme. If you claimed the Feed-in Tariff before it closed at the end of March 2019, you should be receiving export payments. If not, you need to find an energy company that will pay you for your excess electricity.

The Smart Export Guarantee, which replaced the Feed-in Tariff scheme when it closed, provides financial support to homes for the electricity they export to the grid. If you register with the Smart Export Guarantee scheme, your savings from installing solar panels will be considerably higher than without it.

How much will solar panels save on my energy bills?

One of the benefits of solar panels is that because sunlight is free, once you’ve paid for the initial installation cost, they will save your money on your energy bills each year.

There are several factors that can affect how much you’ll save, including where you live, how much time you spend at home (and when you use most of your appliances), the size of your system, whether you have another renewable energy system or PV diverter installed, and whether you’re receiving export payments.

Most households will use around 15-25% of the electricity generated by solar panels, though this will change depending on whether you work from home, how many people stay home during the day, whether you have an electric car, as well as whether you use electricity for your heating and cooking.

The graph below shows estimated annual savings for a typical solar panel installation in London, with and without the Smart Export Guarantee, depending on when you’re at home.

Is it worth getting a solar PV diverter?

If you want to increase how much of your own electricity you use, a solar PV diverter is a good, low-cost option. Instead of sending excess electricity to the grid, a PV diverter switch can power the immersion heater in your hot water tank, storing hot water for you to use later – for example, when you shower in the evening or do the washing up after dinner.

A PV diverter will cost you an extra £800 on average, but it will also increase your energy bills savings each year. By using more of your own electricity, you won’t need to buy as much from your energy supplier at times when your solar panels aren’t generating electricity.

If you’re interested in a PV diverter, speak to your installer. For any solar panel installation, we recommend you choose an installer and system that have been certified through the Microgeneration Certification Scheme (MCS). Search the MCS website to find a solar panel installer near you.

Solar thermal

Solar water heating, or solar thermal, is a sustainable, renewable alternative to heating systems powered by fossil fuels, such as gas boilers.

Solar thermal systems collect heat from the sun, which is then used to heat up water stored in a hot water cylinder or thermal store. You may need to use a boiler or immersion heater as a back-up to heat up the water more to reach the temperature you want.

Most solar water heating systems are used to provide the hot water you need for bathing, showering and your hot water taps. While it works all year round, you’ll probably need to boost the water temperature during the colder winter months.

  • Solar thermal systems collect energy from the sun using panels or tubes, known as solar collectors. These collectors convert the infra-red section of visible light into heat.

    The two main types of solar collectors are evacuated tubes – a bank of glass tubes mounted onto your roof tiles – and flat plate collectors, which are fixed onto your roof tiles or integrated into the roof itself.

  • There are a few things you’ll need to consider before deciding if solar thermal could work for your home.

    As with solar panels, solar hot water collectors ideally need to be fitted to a South facing roof (or a roof that faces between East and West, but not North). You’ll need around 4 to 5m2 of unshaded space for the system – but this doesn’t have to be a roof. They can be fixed to a frame on a flat roof, hung from a wall or mounted on the ground.

    You’ll also need space inside your home for a larger hot water cylinder that includes a special base coil that connects to the solar collectors outside, as well as either an immersion heater or a second coil connected to your boiler.

    While a conventional boiler (with a hot water cylinder) is often compatible with a solar thermal system, if you have a combi boiler, you’ll need to add a cylinder for the solar hot water system.

    Most solar thermal systems don’t require planning permission, however if you live in a listed building, conservation area or national park, there may be additional restrictions, so it’s best to check with your local planning office first.

  • While costs will vary depending on whether you choose tube or plate collectors, as well as the size of the system you want, a typical solar hot water system will cost around £3,000-£5,000 to install.

    Savings will also vary throughout the year and will depend on the hot water system you’re replacing. In the summer, a solar thermal system should provide nearly all your hot water, however during the winter months this can drop to around 25% – so you’ll need a boiler or immersion heater to boost the water temperature.

    If you replace a gas heating system (i.e. gas boiler) with a typical 4m2 solar thermal system, you could save around £95 a year on your energy bills. This saving increases to £125 a year if you’re replacing an electric heating system, and £200 a year if you’re replacing one fuelled by LPG.

  • If you’ve installed a solar thermal system, there a few steps you can take to ensure you’re getting the most out of your system. Try to make sure that as much of your hot water as possible is taken from the solar supply, rather than heated by electricity in your boiler or immersion heater. This could include fitting a mixer shower rather than an electric shower, for example.

    You should try to use more of your hot water in the evening, after the sun has had time to heat it up. If you tend to shower in the mornings, try to shift this to the evenings.

    It’s also important to learn how to set your hot water controls to get the most of out of your new system. If you had a boiler or immersion heater before installing solar collectors, it was probably set to give you a full tank of hot water in the morning. If you don’t change the set up when you install a solar thermal system, you’ll always start the day with a hot tank, so your solar panels will have nothing to heat during the day.

    Your installer should advise you on how to set up your system correctly. Use an MCS contractor to ensure your solar thermal system comes with a five-year workmanship warranty and at least a 10-year warranty for the panels.

Energy storage

Solar energy systems are often paired with energy storage, allowing you to store the energy you generate to use it later.

Electricity from your solar panels can be stored in electric batteries, or it can be converted into heat and stored in a heat battery. Heat from your solar thermal system can also be stored in heat batteries or in thermal storage options, like a hot water cylinder.

There are three main types of energy storage: electric batteries, heat batteries and thermal stores.

  • Electrical batteries can help you make the most of the electricity you generate from your solar panels. Electricity generated during the day can be stored in an electric battery for you to use later in the day, when your solar panels are no longer generating electricity.

    Home batteries can also be used to store electricity bought from the grid at cheaper times of day, for example overnight, helping you to reduce how much more expensive electricity you use during peak times. Combining your solar panels with an electric battery will save you money on your energy bills, as you’ll need to buy less electricity from the grid and can use more of your own.

  • A heat battery can be used to store either spare heat or electricity that’s been generated by your solar panels or solar thermal system. They tend to be small and light, which means you should be able to fit one in a convenient location in your home, if you can’t find space for a larger hot water cylinder. Heat batteries also have a much longer lifespan than electrical batteries.

  • A thermal store is a highly insulated water tank that’s able to store heat as hot water for several hours – it’s often paired with a solar thermal system. They can store heat from a solar thermal system for you to use later that day.

    As well as providing hot water, thermal stores can also house an immersion heater, which can be powered by your solar PV panels using a diverter switch. The immersion heater heats the water in the thermal store, which you can then use for showering, bathing and in your hot water taps.

Will energy storage save me money on my energy bills?

Electric batteries, heat batteries and thermal stores are not specifically designed to save you money on your energy bills. However, they can help you to use more of the electricity you generate from your solar energy system, which means you’ll need to buy less from the grid.

The cost of any energy storage system will depend on the type you choose, your current energy use and the size of your system. When you speak to an installer, ask them to give you an indication of how much it will cost and how much it could save you on your bills. Search the MCS directory to find a certified battery storage installer near you.

Solar panels and electric vehicles

Installing solar panels is a great way to generate your own electricity to power an electric vehicle (EV). While the size of a solar PV system needed to charge an EV will depend on the size of your car’s battery, a typical 15 panel, 4.2kWp system should be able to charge most electric cars easily.

Solar panels only generate electricity during daylight hours (i.e. when the sun is shining), so if you take your car to work every day you’ll probably need to invest in an electric battery, which can store any excess solar energy generated during the day for you to charge up your car when you get home.

If you want to install an EV chargepoint to make the most of the electricity generated by your solar panels at home, you need to register it with your distribution network operator, or DNO. The DNO is the company responsible for bringing electricity into your home. The UK Government has some grants available to help with the cost of installing electric car charge points.

You may also be interested in learning more about smart charging options for your electric car. Smart charging is a safe and convenient way to charge your electric car at times when demand for electricity is lower, for example overnight or when there’s plenty of renewable energy on the grid.