Oxford PV, Fraunhofer ISE Create Single Photovoltaic Module

Oxford PV and the Fraunhofer Institute for Solar Energy Systems ISE have combined two high-efficiency technologies in a single photovoltaic module. 

To achieve this, they used perovskite-silicon solar cells from Oxford PV and connected them using the Matrix Shingle technology developed by Fraunhofer ISE.

Prof Dr Stefan Glunz, Head of Photovoltaics at Fraunhofer ISE, said, “We are delighted to be able to combine two high-tech approaches from Europe in this PV module. To achieve this, we have cut the solar cells from Oxford PV into shingles, arranged them in a matrix structure, electrically connected them using conductive adhesive, and then encapsulated them.” 

The tandem modules are glass-glass modules with edge sealing to protect the moisture-sensitive solar cells.

The 491-watt rooftop module has an area of 1.92 square meters, and the large-area, 546-watt bifacial module covers 2.13 square meters. Both achieved an efficiency of 25.6 percent across the entire module area. 

Tandem solar cells achieve significantly higher voltages and efficiencies than conventional cells, while the current is lower due to its distribution across two sub-cells. This lower current density is beneficial, as it helps reduce resistive losses within the PV module.

The new PV modules were developed as part of the ‘HoTSun’ research project, funded by the Federal Ministry for Economic Affairs and Energy (BMWE).

Tandem solar cells have the potential to significantly boost efficiency in photovoltaics by applying a perovskite cell a few hundred nanometers thick onto a conventional silicon solar cell, the theoretical efficiency limit rises from 29.4 to 43.3%. 

In Matrix-Shingle technology, the solar cell strips are bonded together using 100% lead-free, electrically conductive adhesives, with the strips arranged in an overlapping and staggered pattern like shingles. This enables complete, homogeneous coverage of the entire module surface. 

Furthermore, Matrix-Shingle technology is characterized by a high tolerance to partial shading. Thanks to the matrix arrangement, the current can flow around the shaded areas, meaning that, depending on the degree of partial shading, twice the power can be generated compared to conventional inter-connected PV modules.

Oxford PV’s perovskite-silicon solar cells and modules are manufactured in a pilot production facility in Brandenburg an der Havel, Germany. The perovskite cell is applied directly onto a silicon heterojunction cell using thin-film processes.