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Solar Electricity

Solar electricity comes from devices called photovoltaic (PV) cells - a completely different technology to solar water heating panels. The cells consist of one or two layers of a semi-conducting material, usually silicon. When light hits the semi-conductors an electric field is created across the layers that sets up a flow of electricity. The greater the intensity of the light, the greater the electricity flow.

PV cells are expensive at the outset, but they produce no carbon dioxide and they could save you £125 or more on your electricity bill each year. Systems are either grid connected, or they store electricity in a battery on site.

Off-Grid
Because the start-up costs are considerable, many people who currently use PV technologies are on sites where grid connection is difficult or very costly. In some situations PV cells work very well combined with wind turbines, since wind is more plentiful in the winter and sunlight in the summer (usually!). Having said that, wind turbines are tricky beasts and need to be sited in exactly the right situation if they are to work at all.

PV versus the Rest
Photovoltaics have several advantages over other renewables. They have no moving parts so they are easy to maintain. They can be used in urban environments, where wind and water power are not practical. As they can be embedded in roofs and walls, they don’t take up extra land or garden space.

PV cells now come in all manner of shapes and sizes, from imitation roof tiles to see-through cells that can sit on a conservatory. The panels are fairly heavy though, so you have to be sure of the load-bearing potential of the structure that is holding them up!

Some local authorities require you to have planning permission before you can fit photovoltaics, especially if you are in a conservation area or a listed building. It is worth checking this out before you even start thinking of the whys and wherefores of PV systems.

Grants
If you want to go ahead, it is worth investigating grants that might help you with layout costs. Or, if you are planning any major roof repairs, it could be worth exploring PV tiles as a way of offsetting some of the cost of normal roof tiles.

Photovoltaics are the focus of a lot of research and it is likely that, as technologies improve, the systems will gradually become more affordable. One avenue of research is looking at how chlorophyll from plants might be used in solar panels – then we could all have green roofs!

Find out more
Low Carbon Buildings Trust: administers UK grants
www.lowcarbonbuildings.org.uk

Energy Saving Trust
www.energysavingtrust.org.uk