In view of the predicted shortage of feedstock silicon for solar cell production in a few years, this project is intended to explore the usability of unconventional silicon sources. This material is called solar grade silicon and is distinct from the electronic grade silicon used in the semiconductor industry. It should be capable of production in large quantities. The objectives are:
-to review current and future industrial sources of solar grade silicon e.g. Elkem, Bayer, TEMAV, Wacker,Siemens...
-to evaluate the available materials. The quality of solar cells is closely related to the chemical purity of the silicon, but it is well known, that different impurities have different behaviours. There is a general agreement that, to be successful on the market, silicon solar cells should have efficiencies well above 10%. Therefore, a fairly high quality for the solar grade material is essential.
A number of goals should be reached in the course of the project : - description of the available techniques to produce "solar grade" silicon, and naming the companies involved.
- specification of the requirements for a material that is good for solar cells with efficiency well above 10%, and comparison of available materials with these requirements.
- Definition of crystallization techniques, that might be able to improve materials by the isolation, and definition of passivation techniques, to improve the material during solar cell processing. These definitions will follow from the best results experimentally obtained during this project on solar grade silicon solar cells. Feedback will be given to the different stages of manufacturing: solar grade material, crystallisation and solar cell fabrication.
Four tasks have to be pursued successively and in parallel to reach the goals. They are strongly interdependent, but formally they can be treated separately:
- prospection and procurement of solar grade silicon on the market - experimental crystal growth
- evaluation of the materials
Funding SchemeCSC - Cost-sharing contracts
79110 Freiburg (In Breisgau)