In more detail, the panels are packed with solar cells. Each solar cell contains two wafer-thin layers of silicon crystal on top of one another. The top layer has been treated so that its atoms are unstable and it has too many electrons, while the bottom layer has also been treated, but this time has too few electrons. The electrons want to move from the top layer to the bottom, but they can’t until the cells are exposed to sunlight.
When light hits the top layer the electrons become ‘excited’ and start to move to the bottom layer. Once electrons move together in the same direction, electricity is created. Two metal contacts are placed on either side of the silicon layers to create a circuit.
Electricity generated by solar panels is direct current (DC), whereas the electricity used in buildings is alternating current (AC), so the electricity has to run through an inverter before it can be fed into the building.
It’s a common misconception. They actually still work on cloudy days, just not as effectively.
There’s a scheme called Feed-In Tariffs, which lets you sell any additional electricity generated back to energy companies.
Find out more about Feed In Tariffs through the Centre for Sustainable Energy – there’s lots of information, help and advice on their website.
Ideally, your roof should face due south at a pitched angle of around 30°. You may also need planning permission or listed buildings consent. The Energy Saving Trust have produced a great guide to choosing a site and getting planning permission – find it here.