How do solar PV panels work?
A solar PV system captures the sun’s energy and uses it to generate electricity. The system will continue to work even in cloudy conditions. Not only could you save money by generating your own electricity, you could also earn money from the Government's Feed-In Tariff.
Technical information made simple
Solar PV panels are made up of solar cells. Each cell is made from one or two layers of semi-conducting material, typically silicon, covered by non-reflective glass. Here’s how a typical system works:
- The light shines on the cell and this creates an electric field across the layers, causing electricity to flow.
- The electricity flows through a cable and is collected at a central point generally under the panels and located in your roof space.
- The electricity produced is Direct Current (DC) and needs to be converted to Alternate Current (AC) by an inverter which is fitted as part of the system. This is AC current is then used in your home to power your lights and appliances.
- If you don’t use all the electricity that you have generated, it will be fed into the National Grid automatically. It is estimated that you will export 50-75% of the electricity you generate. If the system can’t provide you with enough electricity, i.e. at night, the Grid will automatically supply you as it does now, for which you will be charged.
The stronger the sunshine, the more electricity you can produce, but PV cells don’t need direct sunlight to work – you can still generate some electricity on a cloudy day.
The strength of a PV cell is measured in kilowatt peak (kWp). That’s the amount of energy the cell generates in full sunlight. This rating will determine the amount of electricity that you can produce. Typical domestic units are 3 or 4 kWp.
- How much electricity does a PV system produce?
- For every kW of peak power capacity installed on a South facing roof a solar PV system will generate around 800 kWh. This reduces by around 20% for an East or West facing roof.
- Do I need planning permission to install a solar PV system?
- You won't need planning permission for solar PV panels unless they exceed a certain height or the property is listed or in a conservation area, though rules vary depending on which part of the U.K. you live in. Take a look at our Planning Permission page for further information on your region's regulations.
- Are there any grants available for installing solar PV panels?
- The Feed in Tariff is a payback scheme rather than a grant scheme, and has replaced most grants for solar PV systems however, grants may be available from your local council - please contact them for details. The Feed-In Tariff pays you for the electricity you generate using your PV system, as well as any excess electricity generated, which you can export back to the Grid.
- What guarantees do solar PV panels come with?
- It does vary from manufacturer to manufacturer but typically Solar PV panels will come with an output guarantee in the region of 20 and 25 years. The Inverter will have a shorter life, and your should budget to have this replaced once during the life of your system (25 years or more) and therefore has a shorter guarantee, typically around 5 years. The labour guarantee will depend on your installer and your should ask or study the fine print in your quote; 5 years is fairly typical.
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