Over 18% Efficient MC-SI Solar Cells from 100% Solar Grade Silicon Feedstock from a Metallurgical Process Route

Abstract

Based on very promising results for solar cells manufactured in an industrial process reaching 16% efficiency we analyzed if solar grade (SoG) silicon feedstock is capable to match up with electronic grade silicon in high efficiency ranges. Thus we applied a reliable lab-type process on 5×5 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> wafers resulting in 2×2 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> untextured solar cells with an efficiency limit of 18.5% for floatzone (FZ) references. The 5×5 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> wafers were selected out of 12.5×12.5 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> phosphorous pregettered SoG-Si wafers characterized by lifetime measurements. The best solar cell out of 100% Elkem SoG-Si reached η=18.1% stable efficiency certified by FhG-ISE CalLab. This is the highest value for this material reported so far.