By Jan Ove Odden, R&D Engineer, Elkem Solar; Anne Jans Faber, Elkem Solar; Erik Enebakk, Elkem Solar; Steinar Braathen, Elkem Solar; Bjorn Sandberg, Elkem Solar; Kenneth Friestad, Elkem Solar
Solar-grade silicon (SoG-Si) based on metallurgical refining processes, often called upgraded metallurgical-grade silicon (UMG-Si), is expected to play an important role in achieving the solar industry’s necessary cost targets per Wp in order to compete with other energy sources. The broad term ‘UMG-Si’ currently embraces types of silicon feedstock that differ quite substantially in product quality and performance. This paper presents a summary of the work carried out by Elkem on low-cost production of silicon feedstock via a flexible, recycling metallurgical processing route with the lowest carbon footprint on the market. Results are given that qualify Elkem Solar Silicon® (ESS™) as a SoG-Si, with comparable efficiencies to polysilicon (poly-Si) from the traditional Siemens process. The latest results on the performance of modules based on ESS are reported. An indication of the stability of older modules based on SoG-Si feedstock from Elkem is also considered. On the basis of the results, there is no reason to expect modules based on ESS to differ from other commercial modules based on poly-Si. ESS is therefore shown to be a viable alternative to conventional poly-Si, but with the additional benefit of lowering specific energy use and cost per Wp.