Fraunhofer ISE uses its own Matrix Shingle cell interconnection technology for the tandem PV modules, which comprise Oxford PV’s Perovskite-Si tandem cells
According to the institute’s press release, the rooftop variant can deliver a power output of up to 491 W and the bifacial variant of up to 546 W
Both modules have a maximum rated efficiency of 25.6%, claims the team
These pilot modules will be displayed during Intersolar Europe 2026
Fraunhofer ISE, a German PV technology research institute, in collaboration with Oxford PV, a perovskite-Si tandem technology specialist, have developed Shingled Perovskite-HJT tandem PV modules under the German government-backed ‘HoTSun’ research project.
According to the German institute, these modules were fabricated at Oxford PV’s pilot production facility in Brandenburg an der Havel, Germany for which the latter provided its perovskite-Si tandem cells. The cell maker applies a few-hundred-nm-thick perovskite cell over an HJT bottom cell via thin-film processes. While the institute didn’t share the average efficiency of these cells, it acknowledges the potential of theoretical efficiency that can reach 43.3% from 29.4%.
The tandem modules developed by the team comprise multiple small strips that are overlapped with 100% lead (Pb) free electrically conductive adhesive (ECA) along the long edges, rather than using conventional ribbon-based soldering. This cell layout creates a module that aesthetically looks like shingles. Unlike the standard shingled modules, the German institute has incorporated its own interconnection technology, Matrix Shingled. Here, each of the serially interconnected rows of cells contain parallel-interconnected solar cells, like a matrix, instead of forming parallel strings.
After that, this cell-matrix, along with encapsulants, is laminated with the front and rear glass, while its edges are sealed to protect against moisture ingression.
According to the CTO at Oxford PV, Ed Crossland, the tandem cell’s current distribution across sub-cells reduces current density, which helps lower resistive losses compared to a conventional Si cell. The tandem cells also achieve higher voltage and efficiency. These attributes lead to cutting wider strips with a longer current travel path compared to traditional shingled modules, added Crossland.
Together, these tandem cells and interconnection technology result in a glass-glass monofacial rooftop PV module with a maximum power output of 491 W within 1.92 m² dimensions. Meanwhile, its glass-glass bifacial counterpart is rated for a power output of up to 546 W within a 2.13 m² size. Both modules achieved a maximum efficiency of 25.6%, claimed Fraunhofer ISE.
From an operational and reliability perspective, this matrix technology extracts additional current compared to a traditional shingled design during partial shading. Unlike restricting current flow through reverse-biased shaded cells in a normal shingled module, its series and parallel cell interconnection allow current to bypass the shaded area. Additionally, its lower processing temperature, typically during the lamination stage, compared to the solder-based stringing process, eliminates the need for copper ribbon-based interconnection.
The absence of copper reduces potential mechanical stresses along the cell long edges and lowers production costs, added Crossland.
A sample rooftop variant will be displayed at Fraunhofer ISE’s booth in hall A1.440, while its bifacial peer is expected to be showcased at Oxford PV’s stall in hall A4.540, during Intersolar Europe 2026.