Inline Plating of Ni/Cu Contacts for Industrial TOPCon Si Solar Cells—Status and Outlook

Abstract:
This article explores an inline plating metallization technique aimed at reducing silver usage in the production of tunnel oxide passivated contact (TOPCon) silicon solar cells. Utilizing ultrashort-pulse UV laser patterning combined with electrochemical deposition of Ni, Cu, and Ag, this approach has successfully achieved efficiencies up to 24% with silver consumption reduced to 1.1 mg/Wp. The process has been applied using pilot line equipment developed by RENA Technologies GmbH. This work not only demonstrates the potential of inline plating for cost-effective solar cell manufacturing but also addresses industrially feasible mitigation strategies for challenges such as contact adhesion and process stability. These include strategies to avoid insufficient Ni nucleation and uneven plating current injection, which are critical for achieving low contact resistivity and high fill factors (FF). As a result, FF of (82.1 ± 0.3)% were demonstrated for a batch of 186 TOPCon solar cells (M10 wafer size). In addition, reliability tests on fabricated mini modules demonstrate promising resistance to degradation. This research advances TOPCon solar cell technology by providing deeper insights into the piloting of inline plating technology for cost-effective and silver-lean metallization of TOPCon solar cells.