Germany's Fraunhofer Institute for Solar Energy Systems (ISE) has reported a peak cell efficiency of 24% for bifacial TOPCon solar cells plated with nickel/copper/silver contacts, in which silver consumption was reduced by over 90%.
They claim this efficiency is 0.5% higher than their industry partner's reference cells that were metallized using silver screen-printing process.
The ISE researchers managed to lower the use of silver in the process by decreasing the width of the laser contact openings to a maximum of 5µm, along with other factors. In other words, printed silver was substituted by a stack of the three materials. The electroplating process for metallization developed by the team was tested for industrial suitability on equipment supplied by Rena Technologies GmbH, added Fraunhofer ISE.
The research work is funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) and aims at replacing silver solar cells contacts with copper. Since copper is more easily available, 'about 100 times cheaper' and electroplated copper is compact and highly conductive, the researchers are working to develop alternative materials and processes for solar cell metallization.
Both the institute and Rena will continue to work on further increasing the efficiency and develop the technology.
Details about the plated metallization for the project are available in a research article in the scientific journal Progress in Photovoltaics.
Fraunhofer ISE said the team is also developing a copper electroplating process for the metallization of equally promising silicon heterojunction (HJT) solar cells. It will be transferred for industrial production by the institute's spin-off company PV2+.
A recent report of TaiyangNews on TOPCon solar technologies delves into developments associated with its production and processes. It is available for free download on our website (see TaiyangNews TOPCon Solar Technology).