Solamet reported that silver-coated copper pastes containing as little as 30% silver achieved efficiencies comparable to conventional 100% silver formulations while remaining suitable for stencil printing
Seed-layer approaches combining a fired silver contact layer with a low-temperature-cured silver-coated copper top conductor can reduce silver usage but require additional printing and curing steps
Pure copper top-conductor architectures offer even greater silver-saving potential, though they introduce additional challenges related to sintering, curing, and process integration
While lean-silver formulations and nickel blending offer incremental reductions in silver consumption, deeper savings may require changes to the metallization architecture itself. Several seed-layer concepts are currently under evaluation, combining conventional silver contacts with alternative conductor materials to reduce silver usage while maintaining cell performance. For more on lean-silver formulations and nickel blending, see our previous article, Lean-Silver Pastes Gain Attention In TOPCon Metallization.
Another parallel approach is a silver seed layer topped with a silver-copper paste, in which the seed layer undergoes high-temperature firing, while the top layer of silver-coated copper is cured at low temperature, similar to HJT processing. According to Solamet, the paste passed internal reliability testing and was also found suitable for stencil printing. The formulation has additionally been improved for storage stability. Testing of viscosity and resistivity at room temperature for more than a month showed fluctuations within the acceptable range. The company also evaluated different copper loadings and reported that pastes containing 50% silver, and even 30% silver, achieved efficiencies comparable to those of conventional 100% silver formulations.
From a manufacturing perspective, however, several challenges remain before large-scale adoption can occur. JTPV’s An pointed out that the process requires double printing, making it difficult to accurately align a 40 μm silver-coated copper finger on top of a 20 μm seed layer. In addition, an extra printer and a low-temperature curing furnace are required, increasing capital expenditure. Cost savings are also currently limited by the premium associated with producing silver-coated copper powders. For example, a paste containing 20% silver may only reduce paste cost by about 50%, rather than the 80% implied by the silver reduction. According to An, this gap is expected to narrow as production volumes increase and economies of scale improve.
The final approach under evaluation replaces the silver-coated copper top conductor with a low-temperature-cured copper paste, while retaining the silver seed layer for fire-through contact formation. Achieving high-quality copper metallization depends on factors such as copper powder morphology, sintering additives, and surface treatments, all of which influence conductivity and interface quality. Initial testing indicates performance comparable to conventional silver-based metallization. However, copper-based systems introduce additional process complexity, particularly around curing and sintering conditions, which may require new equipment and integration strategies.
Overall, reducing silver content through lower-solids formulations represents the simplest pathway, followed by approaches such as nickel blending. In contrast, seed-layer architectures combined with either silver-coated copper or pure copper top conductors offer greater silver-saving potential but involve significantly higher process complexity. These approaches require double printing and careful thermal management because the silver and copper layers demand different firing and curing conditions. In simple terms, the greater the process complexity, the greater the potential cost savings.
The text is an edited excerpt from TaiyangNews’ report on Cell & Module Technology Trends 2026, which can be downloaded for free here.