how solar pv works

Photovoltaic, "fotovoltayik", (PV) comes from Latin:
PHOTO = light
VOLTAIC = electricity

A PV cell is made up of two thin layers of semi-conducting material (silicon) that generate electricity when exposed to daylight.

When light shines on a PV cell the material absorbs some of the light particles called photons. When a photon is absorbed an electron is released within one layer of the semi-conducting material.

These "free" electrons will be attracted towards the other layer of semi-conducting material so they move across the boundary between the layers.

This movement creates a flow of electricity between the two layers within the cell. This flow is called "current".

Metal contacts (the silver looking solder) take the electricity away in the form of a direct current DC electricity.

A PV panel is made up of a series of PV cells all connected in series. These panels are connected in series on your roof making a solar array. The panels generate DC electricity.

The solar array is connected to an inverter (either in the loft or next to your electricity meter) which is the brains behind the system and converts the DC power into AC electricity to power your household appliances. (Click on the picture above to see a bigger diagram)

So if you use your lights, TV, washing machine, hair dryer etc. during a sunny day they will be powered directly by the sun.

If you have no appliances switched on the electricity is exported to the national grid to supply other people who are using power. At night time or when there's not much sun (i.e. in winter) then your electricity is imported as usual.

You will have two meters , one records how much you export and the other measures how much you import. You will then be sent bills (or possibly cheques on a quarterly basis).