Author: Carl Milner. License: Creative Commons, Attribution 2.0 Generic.
Multicrystalline silicon (multi-Si) solar cells with a conversion efficiency of 22.3% have been made in Germany, using hyperpure polysilicon from Wacker Chemie AG (ETR:WCH).
This new record has been achieved by the Fraunhofer Institute for Solar Energy Systems ISE. The team there optimised important steps of the crystallization and cell manufacturing processes individually to the requirements of the multicrystalline starting material. They used optimised plasma texture and the Tunnel Oxide Passivated Contact (TOPCon) technology for rear side cell connectivity to cut electrical current losses.
“In this process, the structure of only partially melted seed material is applied to the crystal. Our trials have shown that ultrapure granules from Wacker are particularly well-suited for this,” said Stephan Riepe, Head of Group Silicon Crystallization and Epitaxy Materials at Fraunhofer ISE.
Karl Hesse, who is leading Wacker Polysilicon’s research and development unit, said that the work by the institute shows that the multicrystalline solar technology based on high-quality polysilicon “is nowhere near reaching its limits”.
Wacker supplied the granular silicon and other materials for this work from its plant in Burghausen, Bavaria.