Over 90 % of the worlds solar cells are made from silicon but they are not particularly efficient at converting light to energy. They are made from layers of high purity crystal more than 150 micrometers thick which is costly to produce. Thin-film solar cells are an alternative technology; they convert the sun’s energy using a more efficient semiconductor process and can get similar efficiency using lower purity material that is only 2 micrometers thick. This results in much lower production costs.
The majority of thin-film cells are made from a sandwich of cadmium telluride and cadmium sulfide (CdTe/CdS) which, thanks to recent advances are now approaching the efficiency of silicon cells. The problem with this technology is that cadmium based products are extremely harmful to living organisms. Researchers at Liverpool University in the UK have discovered that magnesium chloride is a good alternative to cadmium chloride. It is extracted from sea water and has uses such as road de-icing and as a coagulant for tofu, the vegan protein foodstuff based on soy milk.
Magnesium chloride is both abundant and hundreds of times cheaper than cadmium chloride. Jonathan Major, a photovoltaics researcher at the University of Liverpool who developed the new magnesium chloride process speculated that solar energy would eventually meet the world's energy needs. "There is enough sunlight falling on the Earth every hour to generate enough electricity for the planet for a year," he said. "The way solar is progressing it will just be a matter of time before it becomes competitive with fossil fuels and eventually replace them."