Monday, 6 July 2009
Solar cell efficiency
The quest to find sustainable ways to power future devices continues. There will be some incremental developments in the photo-voltaic (PV) solar cells but a significant revolutionary step would be ideal. At present many PV cells based on silicon are only 15% efficient at best. A new approach using gallium arsenide (GaAs) cells is claiming over 28% efficiency. Much of the effort at present is going into broadening the absorption spectrum that the cells cope with. The difference in efficiency between Si and GaAs cells means that one square centimetre of GaAs cell should be compared with one thousand square centimetres of Si cell. The current downside is that Si is much cheaper but this may change over time. The use of lenses and mirrors allows light to be concentrated on the cells, typically 500 times. A one centimetre square cell could thus yield around 14 watts of electricity. At a time when the weather has been especially sunny here in the UK, solar energy at an affordable price is something many would look forward to in future.