Development in silicon sheet technologies

The current status of the development of techniques for the production of sheets/ribbons/foils of silicon for solar cells is reviewed. Of the numerous early approaches only a few survived the last years. The paper tries to analyze the technical problems that are encountered as well as the economic constraints. In recent years the issue of high quality of the silicon sheets has become most important since the low-cost/low-efficiency approach to solar modules has obviously become obsolete. In the F.R.G. three different approaches to silicon sheets are persued, the HSW technique by Siemens, the RAFT technique by Wacker Heliotronic, and the SSP-technique by the Fraunhofer-Institute. Although the basic ideas as well as the results of these three methods are very distinct the evaluation of their respective merits seems to be still difficult.