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.
- What does the inverter do in a solar PV system?
- The PV panels generate direct current (DC), which is a different type of electricity to the 240V alternating current (AC) that is used in your property. The inverter converts the DC power to AC power so that it can be used in your house.
- Do I need a three phase electricity supply to install solar PV?
- Systems with up to about 10kW peak power don't need more than a single phase electricity supply, however it is very unlikely that your system will exceed 4 kW peak power. Your installer will advise you exactly what is required.
- Is efficiency important when choosing solar panels?
- Often not, the efficiency of any given panel relates to how effectively it can convert the sun's light. Given that the sun's light is free a panel can simply be made larger to offset a lower efficiency. Only when suitable roof area is at a premium does it make sense to choose high efficiency panels, this will maximise the amount of power that can be generated from the limited space.
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