Solar electricity panels, also known as photovoltaics (PV), enable you to use this electricity in your home, so by installing solar panels, you can generate your own renewable electricity.
Given that you can power your house with a few panels, if you’re looking to make inroads in energy efficiency, solar is an obvious way to move off the grid and consume a better source of electricity.
Costs have also halved in the past decade, and this together with tax incentives and advances in technology have made Solar PV more attractive to homeowners.
How do they work?
Solar PV panels consist of many cells made from layers of semi-conducting material, normally silicon, and when light shines on this material a flow of electricity is created.
Contrary to common perception the cells don’t need direct sunlight to work and can even work on cloudy days, however the stronger the sunshine, the more electricity can be generated.
Solar PV systems are made up of several panels, with each panel generating around 355W of energy in strong sunlight, but this is variable. 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.
Different types of solar panels
There are three types of solar panels that can be used for domestic purposes: monocrystalline, polycrystalline, and thin-film.
Monocrystalline panels have the highest efficiency, but cost the most. Polycrystalline tend to be the most affordable. The more efficient monocrystalline solar panels cost £1 to £1.50 per watt, whereas a polycrystalline panel costs £0.90 to £1 per watt. *estimated 2025 prices
Thin-film panels take up a lot of space, are less efficient and have lower power capacities than mono and polycrystalline solar cell types and tend to be used in solar farms, to power street lights or where weight is a concern.
Considerations
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 can be considered, but North facing roofs are not recommended. Generally speaking, a system facing East or West will yield around 15-20% less energy than one facing directly South.
You also must consider any nearby buildings, trees or chimneys that could shade your roof and have a negative impact on the performance of your system. The pitch of the roof is important.
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.
Costs
The average domestic solar PV system is 3.5kWp and costs around £5,500.
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.
Output
Most residential solar panels today are rated to produce between 250 and 400 watts each per hour.
Domestic solar panel systems typically have a capacity of between 1 kW and 4 kW.
A 4 kW solar panel system on an average-sized UK house can produce between 3,000 and 3,400 kWh of electricity in a year (in ideal conditions).
A solar panel’s output however depends on several factors, including its size, capacity, your location, and weather conditions.
Schemes and incentives
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.
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.
In Great Britain (England, Scotland and Wales), the SEG 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 you should shop around to find one that works for you.
With the SEG scheme if you have a 3kW system installed, you can earn £75 per year through the SEG. With a 4kW system, you can expect annual earnings of £100, and with a 5kW system you can earn £120 per year.
The ECO4 scheme is a government-funded initiative that offers grants for solar panels and other energy-efficient home upgrades to low-income households
And there will be zero VAT on energy efficient measures such as solar panels, insulation, and heat pumps until 2027.
How Much Can You Save with Solar Panels?
You can cut down significantly on your electricity bills with the use of solar panels. The electricity that you use when your panels are active is entirely free, and it can result in substantial annual savings but this depends on your system size, the number of panels and how naturally energy efficient you aspire to be.
The ultimate savings from solar panels come in the long-term when you save money through the SEG. Your savings after 25 years including SEG can range from about £21,000 to more than £40,000 depending on your system and tariff.
Overall, how much you can save with solar panels will depend on:
Your household electricity consumption;
If you use your appliances during the day when your panels are active;
How efficient your type of solar panel is; and
If you generate an income from solar panel funding schemes
Barriers to Installation
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 Government has advice on how to register your new energy device in England, Scotland and Wales at https://www.gov.uk/government/publications/register-energy-devices-in-homes-or-small-businesses-guidance-for-device-owners-and-installation-contractors/register-energy-devices-in-homes-or-small-businesses-guidance-for-device-owners-and-installation-contra
In Northern Ireland you can get more information at https://www.nidirect.gov.uk/articles/photovoltaic-panels
Are Solar PV systems worth installing?
In short, if you’re in it for the long haul, yes.
The costs of solar panels can be high, to begin with, but the money you save in the long run can justify the initial cost. On top of that, with solar panels, you can increase the overall market value of your property. Additionally, by signing up for funding schemes like the SEG, you can even earn money for the extra energy your panels produce. Therefore, although the installation cost may seem a little steep, the savings from your reduced electricity bills, as well as the reduced carbon footprint of your household energy, should justify the investment.
The typical break-even time for solar panels in the UK is 10.4 years, but this may vary depending on factors such as available grants and schemes in the future, the cost of the system, the size and efficiency of the panels, your energy consumption and the price of electricity.