High Efficiency Potential of Cz Silicon Solar Cells from Metallurgical Process Route

Abstract

A further reduction of cost in photovoltaic industry requires the use of cost-saving feedstock and high solar cell efficiencies at the same time. In this work we present high solar cell efficiencies based on low cost solar grade silicon from metallurgical process route. Therefore a standard industrially applicable solar cell process and an etch back selective emitter process were applied to p-type Cz SoG-Si and poly-Si wafers. Average solar cell efficiencies of 18.3% 18.4% within the standard process and 18.7% using the selective emitter process could be achieved on both materials, demonstrating no disadvantages for the SoG-Si. In addition n-type Cz SoG-Si wafers were processed using boron and phosphorous diffusion to form the p-emitter and the n-BSF respectively leading to bifacial solar cells. Average solar cell efficiencies of 18.8% 19.1% with best solar cells exceeding 19.2% cell efficiency were obtained. Further investigations focused on boron-oxygen related light-induced-degradation, due to its major role for SoG-Si.