Fraunhofer ISE achieves 34.4 efficiency for III-V germanium solar module

From pv magazine Germany

Germany’s Fraunhofer Institute for Solar Energy Systems ISE announced it was able to increase the power conversion efficiency of its record-breaking III-V germanium solar module from 34.2% to 34.4%.

“Compared to the previous record of 34,2% the thing we changed was the layout,” Fraunhofe ISE scientist Laura Stevens told pv magazine. “We used the same cell technology and the same front side glass type. The first module had shingle strings and in the second, better module we connected the cells in a shingle matrix.”

The result was achieved using “shingle-matrix” technology in combination with space-grade solar cells, the German institute said. The previous record of 34.2% was set earlier this year using an 833 cm² module also based on space-grade solar cells from Azur Space. For the latest development, the cell manufacturer adapted its triple-junction solar cell technology to the terrestrial solar spectrum. The anti-reflective front glass structures used for the module were supplied by Temicon.

A key factor in the new record is the use of shingle-matrix technology for interconnecting the solar cells. Developed by Fraunhofer ISE in cooperation with a mechanical engineering partner, the approach is now also used in commercial module manufacturing. The solar cells are cut into narrow strips, arranged in an overlapping shingle pattern, and bonded with electrically conductive adhesive (ECA). This enables direct cell-to-cell contact, eliminates solder-coated copper ribbons, reduces shading, and increases active area utilization.

In July 2025, Fraunhofer ISE achieved 40% efficiency for an indoor III-V solar cell based on an indium gallium phosphide absorber.