Source: Energy & Management Powernews, March 21, 2022
With the help of new production equipment, the Fraunhofer Institute for Solar Energy Systems ISE has succeeded in significantly increasing the manufacturing speed of silicon solar cells.
For the metallization of silicon solar cells and many other electronic components, flatbed screen printing is currently the standard process. Researchers at Fraunhofer ISE have now succeeded in increasing the throughput of printing by a factor of 1.5 on a new production line developed jointly with ASYS Automatisierungssysteme GmbH.
For this purpose, rotary screen printing and flexographic printing processes were used for the first time. With the new equipment, the research team realized a cycle time of only 0.6 seconds per solar cell, according to the institute. After that, the new process can also be used for functional printing in the field of hydrogen technology, sensor technology or power electronics.
"Metallization by screen printing is limited by the process to a throughput of currently about 0.9 seconds per solar cell and track," explained Dr. Florian Clement, head of the Production Technology - Structuring and Metallization department at Fraunhofer ISE. The pressure is thus a bottleneck in the production process of silicon solar cells, but also in the coating process of piece goods components in many other industries.
To be able to further increase the throughput in metallization, a project consortium around ASYS Automatisierungssysteme GmbH and Fraunhofer ISE therefore developed a demonstrator system for the high-throughput metallization of silicon solar cells and other electronic components. As part of a "proof of concept", it has now been possible to show that the throughput of the printing process can be increased by a factor of 1.5. "The system has the technical potential to double the throughput compared to screen printing systems," emphasized Dr. Andreas Lorenz, project manager at Fraunhofer ISE.
The system also features a newly developed high-throughput transport system. In this system, the components to be coated are transported on autonomous "shuttles" at high speed and precision through printing units made by the Swiss mechanical engineering company "Gallus Ferd. Rüesch AG" (part of Heidelberger Druckmaschinen AG) and coated with ultra-fine structures for a precise fit. Depending on requirements, a rotary screen printing unit or a flexographic printing unit can be added, and other printing and coating processes such as multi-nozzle dispensing and gravure printing can also be integrated thanks to the modular design.
The potential areas of application for the new system go far beyond the metallization of silicon solar cells, as the researchers state. While the overwhelming majority of printing and coating systems on the market operate on a "round-to-round" principle and are thus limited to web-shaped substrates, this system addresses the high-throughput coating of piece goods components such as solar cells, printed circuit boards, smart cards and many other components.
The process and system were developed in the "Rock-Star" and "Rock-IT" research projects and funded by the German Federal Ministry of Education and Research (BMBF) and the German Federal Ministry of Economics and Climate (BMWK).
Author: Günter Drewnitzky