There have been two problems when it comes to providing zero energy buildings. The first is the cost of the solar cells and the fact that the material used to make them is toxic. This could now change thanks to Dr. Xiaojing Hao and his team at UNSW who have produced an equally thin film called CZTS. These cells are made from products such as copper, sulphur tin and zinc, and along with being abundant, they do not have the same toxic element that CdTE and CIGS have.
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There is now more than 20% efficiency, and a milestone has been marked on the way from being a project in the lab to a commercial product on the market. Work still needs to be carried out, especially regarding size, but it is an ongoing project. CZTS solar cells can be placed on a number of surfaces and soon they will be made to be flexible or rigid, as well as being cheap enough to allow them to make electricity from sunlight on tiles and windows.
The USA’s National Renewable Energy Laboratory, confirmed this world leading 7.6% efficiency in a 1cm2 area CZTS cells.
There are already companies prepared to get involved and manufacture the item, and it is hoped they will be available in the next few years. Hao believes that technical challenges can be overcome as some of the processes used on CIGS and CdTE have not taken place yet. Eventually, CZTS may be used in homes as they are not toxic and also could be curved to fit other types of roofs.
