Solar Photovoltaic (Solar Electric, Solar PV)
Solar photovoltaic (solar PV, solar electric) uses energy from the sun to create electricity to run appliances and lighting. Solar PV requires only daylight, not direct sunlight to generate electricity and so can still generate some power on a cloudy day
Photovoltaic basics
Photovoltaic systems use cells to convert sunlight into electricity. The PV cell consists of one or two layers of a semi conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers causing electricity to flow. The greater the intensity of the light, the greater the flow of electricity.
PV systems can be connected to the national grid (on-grid) by a suitable inverter or simply to a battery bank (off-grid). Either way they will help off set the running costs of the building in which they are fitted. Photovoltaic panels generally come in the form of rectangular panels of variable sizes, that are usually installed on the roof in very much the same way as solar thermal systems.
Benefits
PV systems produce no greenhouse gases. The system will usually supply a small (1kw to 4kw peak for a typical domestic system) but consistent amount of electricity while the sun is shining. The amount will be at its highest in the summer and at the lowest in the depths of winter.
Over the year the system could be sized to provide your annual need but most of the output would be in the summer. Electricity accounts for about 15%-20% of the total annual energy needed by a typical house (unless you have an electric heating system).
Feed in tariff
From April 2010 customers with MCS compliant systems will be eligible for feed in tariffs
The tariffs fall into two categories:
Generation Tariff:
You are paid for all the electricity that your system has generated even if you use it in your property. The generation tariff is dependent on the size of the system, typically the rate ranges from 36.1p to 41.3p per KWh of electricity generated by your home or premises.
Export Tariff:
Sell surplus electricity back to the grid. If your PV system is producing more electricity than you require, the excess can be exported back onto the National Grid using an export meter.
