Plated TOPCon solar cells & modules with reliable fracture stress and soldered module interconnection

Abstract

This work demonstrates that the application of plated Ni/Cu/Ag contacts for TOPCon solar cells and modules is a reliable alternative to screen-printed metallization. Key advantages of plated metallization is a significant reduction of material costs [B. Grübel et al., in Proceedings 11th SiliconPV Conference, Hamelin, 2021, to be published] due to the substitution of a fully printed silver finger by a stack of a thin nickel seed layer (0.5-1 μm height), highly conductive copper finger (3-10 μm height) and an ultra-thin surface finish by tin (1-3 μm height) or silver (<0.5 μm height). In this study it will be shown that conventional soldering technology can be used to interconnect plated TOPCon solar cells. We manufactured a 60-cell module using industrial processes. The right choice of plating electrolyte allows low stress and ductile metal finger leading to similar reliability in cell breakage experiments compared to state-of-the-art screen-printing metallization.