News: Photovoltaics
22 December 2022
Fraunhofer ISE advancing perovskite–silicon tandem cell and module technology to industrial maturity
Compared with a pure silicon solar cell, stacking a solar cell made of perovskite material on top of a conventional silicon solar cell enables more effective use of the solar spectrum. Scientists around the world are presently researching these perovskite–silicon solar cells, focusing on stability, durability and industrial manufacturing processes.
Between 2020 and 2022, researchers at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany, together with industry partners, developed technologies for the production of perovskite–silicon full-format photovoltaic (PV) modules in the joint project SWiTch. At the cell level, the research teams in the Fraunhofer lighthouse project MaNiTU and in the project PrEs-to, funded by the German Federal Ministry of Economic Affairs and Climate Action (BMWK), succeeded in scaling up perovskite–silicon tandem solar cells from laboratory cell size to wafer size. Within the framework of a recent collaboration agreement with Meyer Burger, Fraunhofer ISE will further intensify its activities in tandem solar cells and modules.
Perovskite–silicon tandem solar cells represent a further development of the conventional silicon wafer-based solar cell technology. Here a perovskite solar cell with a wider bandgap is stacked on top of the silicon solar cell to make better use of sunlight. “Efficiencies of over 35% are possible with these tandem solar cells,” says professor Andreas Bett, institute director at Fraunhofer ISE. “Laboratory-scale perovskite–silicon tandem solar cells have already overcome the silicon cell’s theoretical upper efficiency limit of 29.4%, showing promise for even more efficient solar cells in the future.”
Scaling of laboratory cells to wafer size
On a laboratory scale, the best published efficiency of a perovskite–silicon solar cell is currently 31.3%. However, these laboratory solar cells have a small cell area of about 1cm2, and most of the manufacturing processes used in the laboratory to date cannot be used for industrial production. “We are therefore very pleased that we have succeeded in achieving a certified efficiency of 22.5% for a perovskite–silicon solar cell with an area of more than 100 square centimeters and with industrial screen-printing metallization,” says Dr Patricia Schulze, solar cell scientist working in the MaNiTU project at Fraunhofer ISE. “Our aim is now to realize the high efficiencies of our small laboratory cells on large-area cells using scalable fabrication methods,” she adds. In particular, the Fraunhofer researchers are working on a hybrid deposition process based on two established manufacturing processes to produce perovskite solar cells on double-sided textured silicon solar cells.
First full-format modules built
In the joint project SwiTch, Fraunhofer ISE — together with the project partners — developed interconnection and encapsulation solutions for tandem solar cells. “The interconnection and lamination processes had to be understood and adapted in such a way that the perovskite–silicon solar cells can be integrated into the module without damage, at low cost and with long-term stability,” says Dr Holger Neuhaus, department head of Photo-voltaic Modules at Fraunhofer ISE. First module prototypes with an output of 430W peak have already been produced. The development was accompanied by a detailed analysis of cell-to-module losses and work on the long-term stability of the tandem PV modules. As part of the joint project SALTO, Fraunhofer ISE was able to establish Meyer Burger’s patented SmartWire interconnection technology (SWTC) for full-format modules at Fraunhofer ISE. This low-temperature technology is suitable for interconnecting silicon–perovskite solar cells, in contrast to conventional soldering processes.
Fraunhofer ISE inaugurates Center for High Efficiency Solar Cells
