Generate cheap, green electricity from sunlight
Solar panel electricity systems, also known as solar photovoltaics (PV), capture the sun's energy using photovoltaic cells. These cells don't need direct sunlight to work – they can still generate some electricity on a cloudy day. The cells convert the sunlight into electricity, which can be used to run household appliances and lighting.
The benefits of solar electricity
• Cut your electricity bills. Sunlight is free, so once you've paid for the initial installation, your electricity costs will be reduced.
• Get paid for the electricity you generate. The UK government’s Feed-in Tariffs pay you for the electricity you generate, even if you use it.
• Sell electricity back to the grid. If your system is producing more electricity than you need, you can sell the surplus back to the grid.
• Cut your carbon footprint. Solar electricity is green renewable energy and doesn't release any harmful carbon dioxide or other pollutants. A typical home solar PV system could save over a tonne of carbon dioxide per year – that's more than 30 tonnes over its lifetime.
How do solar panels (PV) cells work?
PV cells are made from layers of semi-conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers. The stronger the sunshine, the more electricity is produced. Groups of cells are mounted together in panels or modules that can either be mounted on your roof or on the ground.
The power of a PV cell is measured in kilowatts peak (kWp). That's the rate at which it generates energy at peak performance in full direct sunlight during the summer. PV cells come in a variety of shapes and sizes. Most PV systems are made up of panels that fit on top of an existing roof, but you can also fit solar tiles.
Solar tiles and slates
Solar tiles are designed to be used in place of ordinary roof tiles. A system made up of solar tiles will typically cost about twice as much as an equivalent panel system. Solar tile systems are not normally as cost-effective as panel systems, and are usually only considered where panels are not considered appropriate for aesthetic or planning reasons.
Cost, savings and maintenance
England, Scotland and Wales
A 4kWp system can generate around 3,800 kilowatt hours of electricity a year in the south of England – roughly equivalent to a typical household's electricity needs. It will save nearly two tonnes of carbon dioxide every year. A 4kWp system in Scotland can generate about 3,200 kilowatt hours of electricity a year – more than three quarters of a typical household's electricity needs. It will save more than a tonne and a half of carbon dioxide every year.
The average domestic solar PV system is 4kWp and costs £5,000 - 8,000 (including VAT at 5 per cent).
If your system is eligible for the Feed-in Tariff scheme it could generate savings and income between £630 and £770 a year depending on your location if you register before April 2015 (based on a 4kWp solar PV system eligible for a generation tariff of 13.88p/kWh). You will get paid for both the electricity you generate and use, and what you don't use and export to the grid.
A 4kWp system can generate around 3,400 kilowatt hours of electricity a year – roughly equivalent to a typical household's electricity needs. It will save over a tonnes and a half of carbon dioxide every year.
If your system is eligible for the NIROC (Northern Ireland Renewable Obligations Certificates) it could generate savings and income of around £795 a year (based on a 4kWp solar PV system eligible for a generation tariff of 16.32p/kWh, using a ROC rate of 4.08p/kWh). You will get paid for both the electricity you generate and use, and what you don't use and export to the grid if you register before September 2015. When applying for NIROCs you will need to apply through Power NI if your system is below 50kW.
Costs can vary between installers and products, so we recommend getting quotes from at least three installers.
Other factors that affect PV installation costs are
• The more electricity the 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 are all about the same price per kWp, but PV tiles cost much more than a typical system made up of panels.
• Panels built into a roof are more expensive than those that sit on top.
Solar PV is eligible for Feed-in Tariffs and you will earn a tariff for each kWh of electricity generated by your system. You will also receive another tariff for each kWh of electricity you export.
If you live in Solar PV is also an eligible technology under the Home Energy Scotland renewables loan scheme. It is an interest free loan from the Scottish Government covering up to 75 per cent of the cost of the system (up to a maximum of £2,500).
This technology is an eligible measure under the UK government’s Green Deal which is a financing mechanism that lets people pay for energy-efficiency improvements through savings on energy bills.
Solar PV needs little maintenance – you'll just need to keep the panels relatively clean and make sure trees don't begin to overshadow them. In the UK panels that are tilted at 15° or more have the additional benefit of being cleaned by rainfall to ensure optimal performance. Debris is more likely to accumulate if you have ground mounted panels.
Once fitted, your installer should 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 trouble-shooting 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 some time during this period, at a current cost of about £800. Consult with your installer for exact maintenance requirements before you commit to installing a solar PV system.
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