Tunnel oxide passivated contact (TOPCon) cells, which currently dominate global crystalline silicon production, consume more silver than earlier technologies such as PERC, making them particularly sensitive to price volatility. Silver prices, on the other hand, have remained at elevated levels in recent months.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE (Fraunhofer ISE) have now significantly reduced silver consumption in TOPCon solar cells. Using an electrodeposition-based metallization process, the team lowered silver use to 1.1 mg/Wp, compared with current levels of 10–12 mg/Wp.
The approach relies on a hybrid metallization process combining high-precision ultraviolet laser structuring with electrochemical metal deposition. Nickel serves as a diffusion barrier to prevent copper migration into silicon, copper provides the main electrical conduction, and silver is limited to a thin capping layer for oxidation protection.
The process has been implemented in pilot systems in collaboration with RENA Technologies GmbH, using inline electroplating equipment. Tests on M10-format cells achieved efficiencies of 24%, in line with conventional screen-printed cells using silver pastes. The researchers also reported fill factors of around 82.1%, indicating low contact resistance and good electrical performance.
Industrial viability was demonstrated under the umbrella of the EURO and SHINE PV research projects, with multiple TOPCon batches processed. Modules produced from these cells passed IEC 61215 reliability testing, showing stability comparable to established technologies.
Electrodeposition of metallic contacts is not new in photovoltaics. It has already been explored in heterojunction (HJT) and interdigitated back contact (IBC) cells to partially or fully replace silver with copper. However, applying these approaches to TOPCon is more challenging due to the absence of transparent conductive oxide (TCO) layers, requiring additional solutions such as nickel interlayers.
Copper-based metallization via electrodeposition also offers supply chain advantages. It reduces reliance on geographically concentrated silver supply and benefits from a more diversified global copper market, including materials, equipment, and chemical inputs.
However, scaling the technology poses challenges. Integrating electroplating tools into existing production lines requires significant capital investment. In addition, maintaining process uniformity, repeatability, and compatibility with high-throughput manufacturing remains critical.
Research is also ongoing to reduce silver use within screen printing, including hybrid silver-copper or pure copper pastes. These approaches face technical limitations in TOPCon, supporting interest in electrodeposition as a key pathway for silver reduction.
Nickel- and copper-based metallization via electrodeposition could reach commercial deployment within two to three years, offering potential reductions in material costs while improving supply chain resilience and sustainability.
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This advancement demonstrates strong industrial potential , as the process has already achieved 24% efficiency and passed reliability tests, suggesting it could be commercially adopted within the next few years