The BOSCO Solar Cell: Simulation and Experiment

Abstract

For bifacial applications, double-sided collecting solar cell structures can be beneficial. The recently introduced “BOth Sides COllecting and COntacted” (BOSCO) solar cell is such a structure and allows the use of standard module interconnection technology. The structure features emitter areas on both sides, which are interconnected by diffused vias. It favors the use of silicon substrates with low-to-medium diffusion length and low resistivity for the maximum benefit compared with other structures, such as Al-BSF and PERC. Within this study, we discuss the potential of the BOSCO cell structure and its applicability for certain silicon material types. Experimental results on different multicrystalline silicon (mc-Si) materials yield monofacial efficiencies (independently confirmed on a non-reflecting chuck) of 17.4% on large-area wafers from block-cast electronic-grade mc-Si and 16.9% for low-quality upgraded metallurgical-grade mc-Si. These values represent a gain of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math>$0.6\!-\!0.7\%_{\rm abs}$</tex-math></inline-formula> compared with Al-BSF cells processed in parallel. The bifacial properties are investigated under outdoor testing conditions, yielding a gain in output power of 13% compared with monofacial operation.