The potential for solar energy is spectacular. In half an hour, enough sunlight reaches the Earth's surface to meet the world's energy demand for a year.

No, it's not. Even on cloudy days, there is a lot of scattered radiation - and so Solar cells generate energy even when it's overcast. The UK, on average, receives two thirds of the radiation of southern Spain and more than half the levels at the Equator.

Each square metre of south-facing roof in Britain receives about 1,000 kilowatt hours (kWh) of solar radiation a year. Given that we use, on average, 3,000-3,500kWh a year in our homes, there's more than enough to supply all our needs. The trick is capturing it.

It's estimated that a solar water-heating system can supply between 80 and 90 per cent of a home's hot water in summer, between 40 and 50 per cent in spring and autumn and between 10 and 15 per cent in winter. A typical Photovoltaic array can supply between a third and a half of a household's energy demand. Some households manage their energy so well that they sell solar electricity back to the national grid.

 

There are 2 main types of domestic solar energy systems:

   1. Solar Water Heating.
   2. Solar Cells (Photovoltaic)


Solar Water Heating

Solar water heating in its simplist form is a flat coated metal panel, insulated underneath and with pipes containing water lying on the surface. As the panel heats from the sun, so does the water held in the pipes. The water is circulated over the panels, and back into the buildings hot water system.

A more advanced (and therefore more expensive) system uses very well insulated evacuated glass tubes. The collector plate is held within the tubes vaccum, and so heat loss is virtually eliminated due to the vaccum and insulation.

In the UK, it is estimated that you can save about 50% of all water heating bills. Both of these types of panel are suitable for home use, and are also available in the UK. This type of system is also great for underfloor heating, general water heating, or even to heat a swimming pool, which is something to consider.


Solar Cells

Usually referred to as Photovoltaic cells/panels (PV), which are composed of specially formulated cells that produce an electric current when light falls upon them. These are the same technology that a solar powered calculator uses for power, only on a larger scale.

The majority of pv solar panels are silicon based, although other materials have or are being used, especially as research and development in this area progresses. Recently scientists have discovered how to acheive similar results using a type of plastic composite which is also able to use the infra-red spectrum, previously not within the ability of existing panels, and thereby making them even more efficient than many current designs.

All of this development means that the overall cost of an installation is rapidly decreasing, especially as demand increases allowing photovoltaic panels to be used for far more projects, including domestic use.