Breaking the Barrier: Unveiling the Potential of Copper for Solar Cell Metallization

As the PV industry rapidly progresses towards a terawatt-scale annual production and installations, significant challenges arise with respect to sustainability. Particularly, the availability of limited resources (i.e. silver for solar cell metallization and interconnection) emerges as a critical concern. Within this work, we focus on different approaches to partly replace the silver-based metallization of TOPCon solar cells by screen-printed copper paste one the one hand and electroplating on the other hand. We demonstrate the feasibility of the screen-printing approach with a champion efficiency of nmax = 21.6 % and a silver reduction by 62 % to 7 mg/W and discuss the potential to further optimize this approach by adapting the grid layout, firing conditions and paste formulation. We further demonstrate large-format TOPCon solar cells with an edge length of 182 mm (M10) with electroplated front and rear side metallization at a champion cell efficiency of nmax = 24.0 % and a silver reduction by 93 % compared to conventional screen printing. The estimated silver consumption of only 1 mg/W is already close to the goal of 2 mg/W which is predicted to be required for a sustainable PV production on multi-terawatt level. Both results underline the potential of copper towards a new silver-free era in solar cell metallization.