The technology behind Solar PV

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 cells are referred to in terms of the amount of energy they generate in full sunlight, know as kilowatt peak or kWp. Each module will generate a certain amount of electricity, and when each of the modules are connected together, the total amount of energy is quoted, i.e. 10 PV modules producing 225 watts will create a system size of a 2.25kWp.

There are two distinct types of PV systems:

• Building Integrated PV (BIPV)
• Stand-alone or retro-fit modules

Stand-alone modules are used to mount onto flat and pitched roofs, and are in addition to any roof coverings such as tiles or concrete. These are the most commonly used PV modules.

Building Integrated PV (BIPV) usual form part of the fabric of a building, and as such are ‘integrated’. These include the solar tile modules which replace the need for tiles on a roof. Other examples also include solar cladding and solar louvres.

Solar cells produce Direct Current (DC) electricity from light. However power used in buildings is normally AC, and so an Inverter is required. This inverter will convert the electricity current so that it’s usable within the home or building.

The PV modules and inverter are then connected to the distribution board serving the lights and sockets of the building, and the energy flows around these to be used. If the energy is not used by these outlets, it is then automatically fed onto the National Grid, for which you will receive payment.