The Fraunhofer Institute for Solar Energy Systems ISE has developed silicon heterojunction (SHJ) solar cells with a silver consumption of 1.4 milligrams per watt peak (mg/Wp), approximately 1/10th the amount used in current industrial production. This was achieved by significantly reducing silver usage on the front side through a silver-copper metallization paste and completely substituting silver with copper paste on the rear side. This development falls below the long-term industry target of 2 mg/Wp, considered necessary for sustainable photovoltaic production.
Fraunhofer ISE is conducting this research to reduce silver dependency in solar cells, enabling sustainable, large-scale photovoltaic production while lowering material costs. The reduction was achieved through an optimized screen-printing process that enabled fine-line front contacts. Researchers used the simulation tool GridMaster to analyze different metallization and screen configurations. The process incorporated ultra-fine mesh screens capable of producing contact openings as narrow as 17 µm. The resulting copper-metallized solar cells demonstrated higher efficiency compared to reference cells with conventional silver contacts. “It turned out that the selection of an optimal screen configuration plays just as important a role as the choice of the metallization paste in minimizing silver usage,” says Andreas Lorenz, project manager at Fraunhofer ISE.
This work is part of the HIT project (High-quality Innovative Printing Forms for SHJ Cells), funded by the German Federal Ministry of Economics and Climate Protection (BMWK), with participation from Meyer Burger Germany GmbH. The project focused on optimizing the composition of metallization pastes and the design of printing screens to reduce reliance on silver, a critical material in photovoltaic manufacturing (see Fraunhofer ISE Unveils Laser System For Fine Mesh Screens).
The largely copper-metallized SHJ cells will be presented at The smarter E / Intersolar Europe 2025 in Munich from May 7 to 9, 2025.
