Fraunhofer Institute for Solar Energy Systems ISEPerovskite-silicon tandem solar cells enable higher efficiency levels than today’s silicon solar modules, but place high demands on module manufacturing. HoTSun is developing gentle processes to reliably interconnect and encapsulate these sensitive cells and process them into industrial-grade PV modules with an efficiency of over 26 percent.
High-Efficiency Tandem Solar Modules For The German PV Industry
HoTSun
Development and assembly of a matrix-shingled PV module at Fraunhofer ISE. In the HoTSun project, gentle processes are investigated for integrating sensitive perovskite-silicon tandem solar cells into reliable module concepts.
Initial Situation
Silicon solar modules are approaching their practical efficiency limits. Perovskite-silicon tandem solar cells can make better use of the solar spectrum, thereby enabling higher efficiency levels. However, they pose challenges for industrial module manufacturing: the delicate cell layers are sensitive to high temperatures, moisture and mechanical stress. Conventional processes such as standard soldering or traditional lamination are therefore only of limited suitability. HoTSun addresses this gap between laboratory success and industrial production with gentle, low-temperature processes for interconnection, encapsulation and reliability assessment.
Objective
HoTSun aims to translate highly efficient perovskite-silicon tandem solar cells into PV modules that can be manufactured on an industrial scale. To this end, the project is developing gentle, low-temperature processes for the electrical interconnection and encapsulation of these sensitive cells. The focus is on conductive polymeric bonding, low-temperature soldering, matrix-shingle concepts and glass-glass module structures. The aim is to produce tandem PV modules with an efficiency of over 26 percent, whose long-term stability is assessed through reliability tests.
Approach
The HoTSun project is developing a particularly gentle manufacturing process for tandem PV modules. The sensitive perovskite-silicon tandem solar cells are not processed using conventional high-temperature processes, but are bonded and encapsulated at low temperatures. To this end, the project is investigating electrically conductive adhesives (ECAs), special low-temperature solders on round wires and matrix-shingle interconnections. Glass-glass structures protect the cells from moisture and mechanical stress. Accompanying measurements and climate chamber tests reveal which combinations of materials and processes are suitable for modules with long-term stability.
Automated processing of a matrix-shingled PV module. HoTSun develops low-temperature processes for gently interconnecting sensitive tandem solar cells and integrating them into industrially scalable module concepts.
Results
HoTSun builds on previous work on high-efficiency tandem PV modules and is further developing them with a view to industrial production. The expected outcomes include suitable low-temperature processes for interconnection and encapsulation, robust glass-glass module structures, and demonstrators with a target efficiency of over 26 percent. In addition, material combinations, module designs and process windows are being evaluated. Reliability tests in the climate chamber will show which approaches are particularly suitable for tandem PV modules with long-term stability.
Demonstrator of a matrix-shingled PV module. In HoTSun, module design, material combinations and process windows are further developed for high-efficiency tandem PV modules.
Funding
The “HoTSun” project is funded by the Federal Ministry of Economic Affairs and Energy (BMWE) as part of the 8th Energy Research Programme, under the funding priority "Photovoltaics".
