A solar PV system works using a number of panels (an array), which are normally mounted on the roof. Each solar panel is made up of photovoltaic cells. These are usually made of wafer-thin layers of silicon and look a bit like blue or black tiles. When daylight hits the cells it creates an electric field. The brighter the sunlight, the more electricity is produced. This direct-current (DC) electricity then flows to an inverter, which converts it into alternating-current (AC) electricity for you to use.
If you install a solar PV system at home, it will automatically feed the power you’ve generated to your appliances, so a lot of the power you use during the day will be free. During the night times, or if you use more energy than you produce, your power supply will switch back to the grid. You won’t notice any disruption or change – just smaller bills.
To make the most of all that free electricity, it’s best to use appliances like dishwashers and washing machines during the day. The system can’t store electricity, so if you produce more than you use during the day, any excess will be fed into the national grid for others to use and the government’s Pay Back scheme will pay the home owner for the electricity.
A 3.5kWp system (kilowatts peak –a PV cell is measured in kWp) can generate around 3,000 kilowatt hours of electricity a year – about three quarters of a typical household’s electricity needs. It will save over a tonne of carbon dioxide every year.
If your system is eligible for the Feed-In Tariff scheme it could generate savings and income of around £635 a year (based on a 3.5kWp solar PV system eligible for a generation tariff of 15.44p/kWh). You will get paid for both the electricity you generate and use and what you don’t use and export to the grid. When applying for FITs you will need to show evidence of your property’s Energy Performance Certificate and this will affect what tariff you can get.
If you know your system size, you can get a tailored estimate for your system using our Solar Energy Calculator.
Solar PV needs little maintenance and the panels should last for 25 years or more and the inverter may need replacing in this period. You just need to keep the panels relatively clean and make sure trees don’t begin to overshadow them. There are a number of specialist window cleaning companies who will clean for you at a cost if you prefer.
