FUTURE CELL CONCEPTS FOR MC SOLAR GRADE SILICON FEEDSTOCK MATERIAL

摘要

The purpose of the work is the investigation of different cell concepts for the newly developed solar grade silicon feedstock (Elkem SoG-Si) from a metallurgical process route, with cost effective refining steps during purification of the silicon. Previous work demonstrated that a standard industrial screen printing process could be adapted to SoG-Si with slight process variation [1, 2]. On large area me SoG-Si solar cells (156 cm~2) efficiencies above 16 % have been demonstrated on an industrial process and confirmed that the SoG-Si is competitive to other PV grade silicon sources. The potential of the SoG-Si material was demonstrated by processing lab-type solar cells with a photolithography based cell process, reaching efficiencies above 18 % on 2×2 cm~2 [3]. Both cell concepts benefits from the gettering during Al alloying, while future cell concepts have to manage without an Al BSF. For example for very thin wafers. Therefore our bifacial cell concept [4] with a boron back surface field (BSF) was investigated on Elkem SoG-Si.