The German research centre Fraunhofer Institute for Solar Energy Systems (ISE) has reduced silver consumption in TOPCon solar cells to 1.1 milligrams per watt, down from a current industry average of 10 to 12 milligrams. Achieved using inline electroplating, the results address one of the key cost and scaling constraints facing today’s dominant cell architecture.
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The process combines ultrashort UV laser structuring with electrochemical deposition of nickel, copper and a thin layer of silver. Nickel acts as a diffusion barrier, copper carries the electrical current and silver is retained only as oxidation protection. The team produced M10-sized TOPCon cells with efficiencies of 24 percent, in line with conventional screen-printed reference cells.
For an industry that has rapidly standardised on TOPCon while facing tightening margins, the reduction in silver intensity is significant. Silver is a major cost input and subject to supply concentration risks. Any credible pathway to reduce precious metal dependence while maintaining performance will attract close attention from manufacturers and investors.
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“So-called nickel/copper electroplating could be firmly established in the photovoltaic market within two to three years,” said Dr Sven Kluska, group leader for electrochemical processes at the ISE. “It would offer many advantages for solar cell manufacturers, even if they have to integrate electroplating equipment into their production process as an initial investment.”
The process was developed and validated in collaboration with equipment supplier RENA Technologies GmbH within the EURO and SHINE PV projects. Multiple batches of cells were metallised on an inline system, delivering consistent efficiencies and a fill factor of 82.1 ± 0.3 percent across 186 cells. Modules produced with the cells showed strong stability in IEC 61215 degradation testing.
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The approach is also likely to affect supply chain dynamics. Silver paste used in conventional screen-printing is closely tied to Chinese supply chains, whereas copper-based electroplating relies on more diversified global sources and equipment suppliers.
“Metallisation via electroplating could also lead to significantly less dependence on China than is currently the case with silver pastes,” said Dr Florian Clement, head of metallisation and structuring technologies at Fraunhofer ISE. “At the same time, we are working intensively to establish European, resilient supply chains for copper-based screen-printing metallisation.”
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Alternative routes are also under development. Hybrid silver-copper and pure copper pastes are already being deployed in heterojunction and IBC cells, but remain more challenging to implement in TOPCon due to the absence of a conductive oxide layer acting as a diffusion barrier. This leaves electroplating as a leading candidate for near-term industrialisation.
If scaled successfully, the technology could help align cost reduction with supply chain diversification. (TF)
