Fraunhofer ISE Research Cuts Silver Use In Solar Cells by 90%

Scientists at Germany’s Fraunhofer Institute for Solar Energy Systems (ISE) have developed silicon heterojunction (SHJ) solar cells with silver consumption of just 1.4 milligrams per watt peak — about one-tenth (which is 90%) of the current industrial standard. The breakthrough comes as global demand for photovoltaics rises, with a shift to a climate-neutral energy system requiring major reductions in silver use, researchers said.

To achieve this, the researchers reduced the silver content in the metallization paste for the front side metallization and completely replaced silver with copper paste on the rear side. An optimized printing process also ensured very fine electrical contacts. The copper-metalized SHJ solar cells achieved higher efficiency than their reference cells with traditional silver contacts.

Reducing Silver Consumption Is Key To Increase PV Consumption

To enable PV production on a multi-terawatt scale, solar cell, and module manufacturer must significantly reduce their silver consumption. In 2024, the PV industry, which continues to grow, already accounted for 32 percent of the silver used industrially worldwide. For long-term sustainable global PV production and to be able to produce sustainably in the long term, 2 milligrams of silver per watt of peak power were calculated as the target. Scientists at Fraunhofer ISE have now succeeded in undercutting this limit for the first time, using screen printing for solar cell metallization.

“Thanks to the balanced combination of silver-copper paste on the front side and pure copper paste on the rear side in conjunction with an optimized fine-line printing process, we were able to produce highly efficient silicon heterojunction solar cells with a minimal silver consumption of only 1.4 milligrams of silver per watt peak,” explains Sebastian Pingel, research associate at Fraunhofer ISE. “In our experiment, the solar cells even achieved a higher efficiency than the purely silver-metalized reference cells.”

The research result is part of the joint project “HIT – High-quality innovative printing forms for the metallization of silicon heterojunction solar cells” funded by the Federal Ministry of Economics and Climate Protection BMWK. The solar cell and module manufacturer Meyer Burger Germany GmbH is involved in the project as an industrial partner.

To optimize the composition of the metallization pastes and the screen configurations for printing the contacts, the research team initially carried out extensive simulations using the specially developed simulation tool “GridMaster”. “It turned out that the selection of an optimal screen configuration plays just as important a role as the choice of the metallization paste to reduce the silver consumption,” says Andreas Lorenz, project manager at Fraunhofer ISE. “Using novel, ultra-fine mesh screens, we were able to print a fine-line front metallization with openings as fine as 17 micrometers, which is considerably thinner than a human hair.”