Multi-busbar solar cells and modules : high efficiencies and low silver consumption

Abstract

Ideally, future photovoltaic modules show higher power output without increasing costs during cell production or module interconnection. Today significant losses occur during stringing the cells in a module by using standard 3- busbar technology. In this paper an elegant approach for a front side design is discussed by using more busbars than the widely used 3-busbar design for the solar cell front electrode. Simulations demonstrated that the multi-busbar design allows higher cell and module efficiencies compared to a state of the art 3-busbar cell design, and in the same time reduces the amount of silver needed for the front electrode. “A conventional full area Al BSF and standard screen printing for the front contact was used for the 6” Cz-Si multi-busbar solar cells and efficiencies of up to 19.5% have been reached. The solar cells were analyzed on cell and module level and a reduction in Ag consumption for the front electrode of >50%abs could be achieved using the multi-busbar cell design. An additional silver reduction was achieved by replacing the rear side Ag/Al pads with tin pads for the soldering process. These changes in solar cell design reduce significantly the metallization costs and in the same time increase the efficiency.