Solar electricity panels, also known as photovoltaics (PV), capture the sun’s energy and convert it into electricity that you can use in your home. By installing solar panels you can generate your own renewable electricity.
Solar PV cells are made from layers of semi-conducting material, usually silicon. When light shines on the material, electrons are knocked loose, creating a flow of electricity. The cells don’t need direct sunlight to work, they can work on a cloudy day. However, the stronger the sunshine, the more electricity generated.
Solar PV cells are grouped into modules, and modules are usually grouped into solar arrays. Modules and arrays come in a variety of shapes and sizes. Most PV systems are made up of panels that fit on top of your roof, but you can also install on the ground, or fit solar tiles.
The electricity generated is direct current (DC), whereas the electricity you use for household appliances is alternating current (AC). An inverter is installed along with the system to convert DC electricity to AC.
Space is a key consideration. As a general guide, a roof area of 10-20 square metres would be enough to deliver between 20% and 45% of the typical household’s electricity needs.
This roof space will ideally face South, will be unshaded, and at a pitch angle of about 30 or 40 degrees.
East or West facing roofs could still be considered, but North-facing roofs are not recommended.
Any nearby buildings, trees or chimneys could shade your roof and have a negative impact on the performance of your system.
Solar PV installations are classed as permitted developments but always check with your local authority before installing in case there are any limits or restrictions apply.
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 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 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.
Costs
The average domestic solar PV system costs around £4,800.
In South England A 3.5kWp system in the south of England can generate around 3,700-kilowatt-hours of electricity a year – that’s the same amount of electricity as it takes to turn the London Eye 49 times. It will save around one tonne of carbon dioxide every year.
The more electricity the PV system can generate, the more it costs – but the more it could save larger systems are usually more cost-effective than smaller systems (up to 4kWp) PV panels about the same price per kWp.
Savings
London, South East England – Annual savings could be as much as £300 per year.
Solar PV needs little maintenance. Keep an eye on nearby trees to ensure they don’t begin to overshadow them.
In the UK, panels that are tilted at 15° or more have the benefit of being cleaned by rainfall to ensure optimal performance. Debris is more likely to accumulate 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.
Once fitted, your installer will leave written details of any maintenance checks that you should carry out from time to time to ensure everything is working properly. This should include details of the main inverter fault signals and key troubleshooting guidance. Ideally, your installer should demonstrate this to you at the point of handover.
Keeping a close eye on your system and the amount of electricity it’s generating (alongside the weather conditions) will familiarise you with 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 about £800. Consult with your installer for exact maintenance requirements before you commit to installing a solar PV system.
As your PV system will be working at its peak during daylight hours, it’s a good idea to think about reorganising domestic activities such as washing, dishwashing, ironing and heating if you do have electric heating. If you’re home most of the day, then this will be easier to do, but if you work during the day then try setting up timers for your dishwasher and washing machine.