The Sunsil-Process: The most energy-efficient process to produce solar grade silicon

摘要

Because of the extremely growing PV industry, new production processes for solar grade silicon with lower costs and energy consumption were established. In the following, the most effective procedure will be explained, the Sunsil-Process, developed by JSSi, a joint venture of Evonik Degussa GmbH and SolarWorld AG. The main steps of this unique process out of monosilane, the complete decomposition of silane to silicon powder in a free-space-reactor, the separation of silicon powder from hydrogen and additional gases, the degasification and the densification and shaping steps are presented. The resulting silicon was characterized and the obtained properties are considered in comparison to a reference level. The suitability of Sunsil-Silicon as fine raw material for the PV industry will be shown. The advantage of the Sunsil-Process in energy consumption in comparison to the state of the art Siemens process is illustrated.