Solar Photovoltaic (PV) systems allow the direct conversion of sunlight into electricity.
The PV cell which enables this reaction consists of one or two layers of semi conducting material, usually silicon. When sunlight shines on the cell it creates an electric field across the layers causing electricity to flow. The greater the intensity of light, the greater the flow of electricity. The amount of electricity generated is measured in kWp (kilowatt peak).
PV modules gather solar energy and convert it into direct current electricity. An inverter converts this DC current to alternating current (AC) for use in the home. Many PV systems are designed to sell surplus energy back to the grid rather than storing energy. This overcomes many the problems associated with batteries: i.e. high cost, storage, limited useful life span and environmentally unfriendly components.
Before installing Solar PV in a domestic setting, it is sensible to take more general energy conservation measures. This ensures the relatively expensive energy investment may be optimised. However, in the UK:
- you can benefit from the Government's feed in tariff which pays a set rate per kWh of electricity generated and an additional rate for any exported back to the national grid, guaranteed by the Government for 20 years.
- Panels generate power even on cloudy days, they simply need light.
- Clean energy means you reduce your carbon emissions by up to 1 tonne per annum.
- Producing your own power protects against rising energy prices.
Potential drawbacks are:
- large area of unshaded south facing roof is required to maximise payback. Smaller systems can be installed, but payback will be longer.
- Panels degrade over time by approximately 20% over 25 years, this however is taken into account in most reputable suppliers calculations.
- It may be beneficial to replace the inverter after 10 years to optimise power generation.