A solar PV panel consists of many cells made from layers of semi-conducting material, most commonly silicon. When light shines on this material, a flow of electricity is created.

The cells don’t need direct sunlight to work and can even work on cloudy days. However, the stronger the sunshine, the more electricity generated.

Solar PV systems are made up of several panels, with each panel generating around 355W of energy in strong sunlight. Typical systems contain around 10 panels and generate direct current (DC) electricity. Because the electricity used for household appliances is alternating current (AC), an inverter is installed along with the system to convert DC electricity to AC. This electricity can be used throughout your home, or exported to the grid.

Space is a key consideration. The average system size is around 3.5kWp and this will typically take up around 20m2 roof area.

An unshaded, South facing roof is ideal for maximum electrical output. East or West facing roofs could still be considered, but North facing roofs are not recommended. A system facing East or West will yield around 15-20% less energy than one facing directly South.

Any nearby buildings, trees or chimneys could shade your roof and have a negative impact on the performance of your system.

Finding an unshaded spot is best, however sometimes shading is unavoidable. Some solar PV systems can minimise the impact of shading using ‘optimisers’. If you don’t have shading, the use of optimisers is not necessary or beneficial, other than the increased monitoring opportunities they offer – they won’t generate more energy.

Solar PV panels are considered ‘permitted developments’ and often don’t require planning permission. However, exceptions apply and it’s best to check with your local planning office for guidance. If you live in a listed building, conservation area or national park, additional restrictions may apply.

If you’re planning to install a solar PV system in your home, you must register it with your Distribution Network Operator (DNO). The DNO is the company responsible for bringing electricity to your home. Usually, your installer will register the device for you.

The UK Government has advice on how to register your new energy device in England, Scotland and Wales.

During daylight hours, you’ll be generating electricity even on cloudy days, but if you’re using more power around your home than your panels are generating, or during the evening when your panels are not generating any electricity, you’ll be supplementing this by importing electricity from the grid.

Reducing your electricity use can help lower your bills and reduce your carbon footprint. If you’re claiming a Smart Export Guarantee tariff, you’ll receive a payment for every unit of electricity you export. Remember to turn devices off and avoid standby.

As your solar PV system will be working at its peak during daylight hours, it’s a good idea to run your electrical appliances such as your washing machine, dishwasher, and iron during the day. If you’re at home, then this may be easier to do, but if you are away during the day, you could try setting timers for your dishwasher and washing machine.

PV diverters are a low-cost and low maintenance option for increasing your own consumption of solar electricity (i.e. using the electricity generated by your own solar PV panels).

Most of the time your solar PV system either:

- Isn’t generating enough energy for your household’s demand, and is supplemented by importing electricity from the grid, or

- Is generating excess electricity above your demand and exporting that electricity back to the grid.

Instead of sending surplus 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. On its own, excess solar energy is unlikely to meet all your hot water needs, but it can help reduce your bills.

A PV diverter switch installation could add around £800 to your installation costs.

With any domestic PV system, there will be times when the electricity you generate is more than you can use or store, so the surplus will be exported to the grid to be used by somebody else. If you want to be paid for exporting, you need to make sure you’re getting an export payment. If you were able to claim the Feed-in Tariff (this closed to new applications at the end of March 2019), then you will be getting export payments as part of that. If not, you need to find an energy company that will pay you for this surplus.

Following the closure of the Feed-in Tariff scheme to new solar PV system applicants in March 2019, the Smart Export Guarantee (SEG) was introduced to provide financial support to small-scale renewable energy generators for the electricity they export to the grid. The savings from solar PV with the SEG are considerably higher than without it.

In Great Britain, the Smart Export Guarantee pays you for the electricity you generate.

In Northern Ireland, you can get paid for any surplus you export – usually estimated based on how much you generate. Several organisations offer this service, so if you’re interested, we recommend researching their offers to find one that works for you.

The average domestic solar PV system is 3.5kWp and costs around £7,000.

The amount you will pay is influenced by the size of array and will be affected by any difficulty with access to your roof. Some of the installation costs can be shared if you already have scaffolding up for roof repairs or if you are building a new house. Costs are also affected by whether you choose panels or tiles, and whether you opt for building-integrated panels or choose panels that sit on top of your roof. Panels on top of the roof are the cheapest option, while tiles are the most expensive for the equivalent system.

The cost of ground-mounted systems is more difficult to predict, as there are more variables such as the type of mounting frame, and how far away it is from the house.

Solar PV systems need little maintenance. Keep an eye on nearby trees to ensure they don’t begin to overshadow your system.

In the UK, panels that are tilted at 15 degrees or more benefit from being cleaned by rainfall, which helps to ensure optimal performance. Debris is more likely to build up if you have ground-mounted panels, or if you live in an area with more dust in the air. In these cases, you might need to have the panels cleaned occasionally.

Once fitted, we will leave written details of any maintenance checks that you should carry out to ensure everything is working properly. This should include details of the main inverter fault signals and key troubleshooting guidance. We will demonstrate this to you once the system has been installed.

Keeping a close eye on your system and the amount of electricity it’s generating (alongside the weather conditions) will help you understand what to expect and alert you to when something might be wrong.

The panels should last 25 years or more, but the inverter is likely to need replacing sometime during this period, at a cost of around £800 (depending on system size and the manufacturer). Some inverters have online monitoring functions and can warn you by email if the system fails.

Most inverters have warranties of five years as a minimum, which can often be extended up to 15 years.

An energy-storage system, also called a home or solar battery, lets you capture electricity so you can use it at another time. For example, you can store the electricity your solar panels generate during the day and use it at night.

This relatively new technology may be worth considering if you generate your own energy at home with solar panels but could use more of it outside daylight hours – or plan to start doing so.

If you have solar PV panels, or are planning to install them, then using home batteries to store electricity you’ve generated will help you to maximise the amount of renewable energy you use. In fact, 60% of people who have, or would consider, a home battery told us the reason was so they could use more of the electricity generated by their solar panels.*

Home-energy storage will also reduce the electricity you use from the grid, and cut your energy bills. If your home is off-grid, it can help to reduce your use of fossil fuel back-up generators.

Even without solar panels, you may be looking to make use of time-of-use tariffs with a battery. These let you store up electricity while it’s cheap (overnight, for example) so you can use it during peak times.

A few energy companies have launched these already, and we expect to see more of them as they can help to balance energy supply and demand, and reduce the need for additional fossil-fuel generation at peak times.

If, for example, it's a windy night and lots of wind turbines are generating electricity for the grid that no-one is using, it makes sense to make the most of that with battery storage.
If you’re at home during the day and already use a large proportion of the electricity you generate through solar panels, or divert surplus electricity to heat your water (for example), then a battery may not be right for you.

This is because home-energy storage will cost you upwards of £2,000, so you’ll need to make sure it's a worthwhile investment and you'll get your money back on your energy bills. With grid electricity currently very expensive, the pay back times might now be quicker than you think.

The average home uses around 8kWh of electricity per day. The capacity of new lithium-ion batteries ranges from around 1kWh up to as much as 15kWh.

Ideally, you want a battery that will cover your evening and night-time electricity usage, ready to be charged up again when the sun comes up. You'll also need to bear in mind how much your solar panels can generate, as there's no point buying a battery that's bigger than they can fill.

With a battery that is well chosen for your home's energy use and your solar panels' output, you should find that you can have enough electricity to serve your evening needs for most of the year. You might find that you are still drawing on grid electricity for some of the longest winter nights.

Whether a battery will save you money depends on:

-the cost of installation
-the type of system installed (DC or AC, c-hemistry of the battery, connections)
-how it’s used (including the effectiveness of the control algorithm)
-the price of electricity (and how it changes during the lifetime of your system)
-the battery’s lifetime.

Several battery systems come with a 10-year warranty. They require little maintenance, so the main cost is the initial installation. However, solar PV panels can last 25 years or more, so you should factor in the cost of replacing the battery at least once into your total costs.

Batteries are expensive to buy, but prices are dropping all the time, as are solar panel prices. With electricity prices at record highs, the payback times are improving.

If you have a smart meter, your export payments will be based on actual export data. However, if you also have a home battery installed, your export payments will be estimated at 50% of what you generate. This is because your export meter cannot determine whether electricity exported from your battery was originally generated by your panels or taken from the grid.

If you are looking to install solar panels and a solar battery, new Smart Export Guarantee (SEG) tariffs mean that energy firms will pay you for any excess renewable electricity you have generated and export to the grid. All suppliers with more than 150,000 customers have to offer them, but the rates are not very generous.

Compare rates to find the best for you – but check that you’re eligible if you have storage installed.

While battery prices are coming down, it’s still a significant investment.

The best option is to pay for your battery upfront using your own savings. If you don’t have the cash to do this, you could consider a loan. However, remember you’ll have to pay interest on money you borrow, so make sure that gains made from battery storage would outweigh this.

If you live in Scotland, the government offers interest-free loans to homeowners to fund energy-saving improvements, including energy storage. You can borrow up to £15,000, which you must repay within 10 years. See Energy Saving Trust Home Energy Scotland to find out more.

No. You can charge a home battery using electricity you buy from the grid. If you have a time-of-use electricity tariff you can save money by charging your battery when electricity is cheaper, and using the power from it so you're not buying from the grid at pricey peak times.

But most people do not have time-of-use tariffs yet. These will become more widely available as smart meters are rolled-out, as smart meters will make it easy for energy companies to see exactly when you've used energy. Economy 7 and Economy 10 are types of traditional time-of-use tariffs, usually linked to storage heating systems.

Both electric vehicles and plug-in hybrid electric vehicles require an EV charger to keep the battery full, just like any chargeable device or electronic.

At its most basic, an EV charger pulls an electrical current from either a 240v outlet or the grid it’s hardwired to and delivers that electricity to the vehicle, just like any other appliance or device you charge by plugging into the wall.

If you are parking in front of an EV charging station, there are a few things you’ll need to determine. For one, the station may be provided free of charge, may require a key FOB or other access device, or it may require credit card payment—similar to other parking situations such as only being allowed to park in a lot for free if you’re a customer, or you may need to pay a parking meter during specific times and on specific days. The device and posted notices should make it clear how to use the charging station.

There are three main types of electric vehicle charging: Level 1, Level 2, and Level 3, mostly known as DC fast charging or rapid charging.

Level 1 charging can be done through a standard 120-volt wall plug, which can be found throughout U.S. homes and garages. Level 1 charging is extremely slow and is typically reserved for home charging during overnight hours. It can more than 24 hours to fully charge an EV battery through Level 1 charging.

Level 2 chargers use 240-volts and are usually found in homes and public charging stations. A Level 2 charger is much faster than a Level 1 charger – up to 15 times faster! Level 2 EV charging stations need a dedicated 208-/240-volt outlet, which is the type of outlet used for an electric clothes dryer. Most homes don’t have an extra outlet of this kind in the garage or driveway and need a dedicated circuit installed by an electrician.

DC fast chargers or rapid chargers use 480+ volts and are the fastest way to charge an electric car.

Level 1 and Level 2 chargers deliver alternating current (AC) to an electric vehicle, which is converted to direct current (DC) by the EV battery. An EV battery can only accept DC power. On the other hand, a DC rapid charging station delivers DC directly to the electric vehicle and the electrical current does not need to be converted. Level 1 and Level 2 chargers recharge EVs much slower due to the AC/DC conversion process.

There are three types of Level 3 charging or DC fast charging: Combined Charging System (CCS), CHAdeMO (“CHArge de MOve”), and Tesla Supercharger. CCS allows AC/DC charging through the same port, cars with CHAdeMO have a separate port for AC charging.

Not all EVs can charge through a DC fast charger. DC fast chargers are only used in commercial applications and cannot be installed in homes for several reasons – homes don’t have the electrical capacity for a DC rapid charger, EV drivers don’t need that quick of a charge for overnight home charging, and a DC fast charging installation is much more expensive than a Level 2 due to the electrical infrastructure improvements necessary.

On the other hand, when it comes to commercial applications a DC fast charging station may be the ideal EV charging solution for a business. For example, DC rapid chargers are perfect for fleet charging and for highway public charging stations.

How long it takes to charge an electric vehicle depends on the type of EV charging point you are using.

Level 1 electric vehicle chargers will charge an EV at a rate of 2 to 5 miles per hour.

Level 2 EV charging points can charge an EV up to 15 times faster than Level 1 charging points. They can charge 13-75 miles per hour.

Level 2 EV chargers are efficient and easy to use. A level 2 charging station is the perfect solution for home charging.

DC Level 3 EV chargers can charge 80% of an EV’s battery in 10 to 30 minutes. This is of course the fastest charging option available on the market today. DC fast chargers are not compatible with all EVs.

An air source heat pump, sometimes referred to as an air-to-water source heat pump, transfers heat from the outside air to water, which heats your rooms via radiators or underfloor heating. It can also heat water stored in a hot water cylinder for your hot taps, showers and baths.

Heat from the air is absorbed into a fluid. This fluid then passes through a heat exchanger into the heat pump, which raises the temperature and then transfers that heat to water.

The external unit for a heat pump is identical for both monobloc and split heat pumps. Noise is created by large fans moving air across the heat exchanger.

Unless the heat pump is working very hard (ie in cold weather or producing high temperature water), you can expect the noise to be a similar volume to a fridge, if you were standing within a couple of metres. You could easily hold a normal conversation next to it, without raising your voice. As it gets colder outside, this noise will increase while it’s operating, but should still allow you to hold a conversation easily, only raising your voice a little.

The inside unit for a split system only contains valves and pumps and makes very little noise at all.

A standard heat pump doesn’t provide hot water on demand like a combi boiler, so you will need a way of storing hot water for when you need it. The size of hot water cylinder required will depend on the amount of hot water that your household typically uses, but the cylinder can usually be fitted inside any cupboard that measures around 80x80cm.

If you don’t have space for a hot water cylinder, you still have options. Some hybrid systems are designed with the heat pump providing heating and a boiler providing hot water on demand. You could also consider installing a heat battery, which takes up less space than a hot water cylinder. Instantaneous hot water heaters are also available and can be installed under your kitchen sink to provide a smaller amount of hot water.

The cost of an air source heat pump varies depending on the size of heat pump, the size of the property, whether it’s a newbuild or an existing property, as well as whether you need to change the way you distribute heat around your property. Try our estimator tool to find out more.

While the compressor and pumps need electricity to work, they use less than the quantity of heat they move from outside to inside. The amount of heat energy moved versus the amount of electrical energy used depends on the source temperature and the output temperature, so it varies constantly throughout the year as outside temperatures change.

How this will affect your energy bill will depend on several factors, including:

- What fuel you are replacing and how much it costs.
- Your electricity tariff.
- Which type of heat pump you install and how efficient it is.
- The design of your central heating system.
- Your location and its average air or ground temperatures throughout the year.
For people using gas boilers (not LPG or oil boilers), heat pumps are likely to be slightly more expensive to run unless particular attention is paid to ensuring maximum efficiency of the heat pump in the heating system by using best practice radiator / underfloor heating design. However, as utility prices fluctuate over time, we expect that heat pumps will become the cheapest as well as the lowest carbon form of heating available.

For those on LPG or oil, annual variations in prices mean that it’s difficult to give an exact estimate of annual heating costs. For example, heating oil has typically fluctuated between 40-65 pence per litre over the last five-year period, with a general upward trend in price. Unless you can buy oil or LPG at the very cheapest time of the year to cover your entire annual use, heat pumps should save you money on running costs assuming a well-designed system is installed.

Before installing a heat pump, it’s important to check if you need to apply to your local planning authority for permission. Most heat pump installations are considered ‘permitted developments’, meaning no permission is required. However, there are exceptions, and it’s best to check with your local planning department before proceeding, especially if you live in a listed building or conservation area.

You should also inform your local district network operator (DNO) that you are planning to install a heat pump. The DNO is the company responsible for bringing electricity from the network to your home. You can ask your installer to assist you with this, as they will have all the information required to complete the forms.

As with any heating system, a heat pump needs to be well maintained to operate as designed – though luckily most heat pumps tend to be easy to maintain with minimal input required from the end user.

With regular scheduled maintenance, you can expect a heat pump to operate for 15 years or more.

Typical checks include a visual inspection of the water pump, external pipes, fittings and electronics. Ground source heat pumps may also occasionally need to be re-pressurised or have the quality of the antifreeze checked, which can be done by a professional every 2-3 years.

Most of the time your solar PV system either:

- Isn’t generating enough energy for your household’s demand, and is supplemented by importing electricity from the grid, or

- Is generating excess electricity above your demand and exporting that electricity back to the grid.

Instead of sending surplus 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. On its own, excess solar energy is unlikely to meet all your hot water needs, but it can help reduce your bills.

A PV diverter switch installation could add around £800 to your installation costs.

Air source heat pumps are the most common type of domestic heat pump in the UK and are suitable for many types of home.

If you have a garden or large outdoor space, you may be interested in finding out more about ground source heat pumps.

If you don’t have radiators or underfloor heating, and can’t or don’t want to install these, you might be interested in finding out more about air-to-air heat pumps. Air-to-air systems are more commonly associated with smaller properties such as flats and park homes.