BC cell makers like AIKO, LONGi, and SPIC are pursuing copper-based metallization to reduce reliance on silver
AIKO is refining both copper plating and copper paste development, while also adopting stencil printing
LONGi has mapped out strategies for both silver-lean and silver-free processes, noting that BC architecture is more compatible with low-cost metals than TOPCon
As with any other cell technology, metallization remains one of the most critical and cost-sensitive aspects also for BC solar cell manufacturing. While silver paste-based screen printing is still the standard today, all major BC manufacturers are actively exploring ways to reduce or replace silver, with a clear focus on copper-based solutions. Adopting ZBB is a common strategy to reduce silver consumption.
For now, screen-printed silver paste remains the dominant choice across the board. As SPIC noted, screen printing is still considered the most straightforward and reliable approach. LONGi says it has already achieved lower silver consumption per watt than TOPCon, without having to introduce low-cost base metals yet – a result made possible in part by adopting ZBB designs that reduce paste usage.
Looking ahead, reducing silver usage is a shared priority. AIKO currently employs a dual metallization strategy for its BC cells, using both copper plating and silver paste screen printing. To reduce costs associated with silver, the company is exploring improvements in the screen printing route by adopting stencil printing, which allows for finer fingers with less silver consumption. At its Zhuhai facility, AIKO continues to refine copper plating, aiming to increase the aspect ratio of metal lines with a primary focus on improving cell efficiency. Simultaneously, the company is developing copper paste technology at its new base, with the goal of at least partially replacing, if not completely eliminating, silver paste in the future(see Laser Structuring And Efficiency Challenges In BC Cell Production).
LONGi, too, is preparing for a silver-free future. While its current process is still silver-based, the company emphasized that it has developed a comprehensive strategy for both silver-lean and silver-free metallization. Unlike TOPCon, BC structure is not all that susceptible for various reasons, which gives it a natural edge in adopting cheaper metals like copper or aluminum. Adopting ZBB is also relatively complex for TOPCon. The technology uses laser-enhanced contact optimization on the front, which prevents it from being silver-free, at least as of now. The contacts are still present on the front and low-cost metals with higher resistivity, requiring a higher contact cross-section to compensate for the conductivity. This increases shading, which is not ideal. The structure is also not very supportive of using different contact materials for the front and rear. Above all, any such optimization requires additional CapEx, which may not be feasible in the current context of overcapacity. BC is free from all these limitations, meaning it is easier to adopt the low-cost metallization solutions.
SPIC is also exploring the transition to copper paste, although it is currently limited to R&D. The company views copper paste as the most viable path forward and expects it to enter production within the next 2 to 3 years, depending on industry progress. Plating does not currently appear to be part of SPIC’s metallization roadmap.
This text is an excerpt from the TaiyangNews Cell & Module Technology Trends 2025 report, which can be downloaded for free here.