Experimental Investigation of 2-Terminal Voltage-Matched Perovskite/Crystalline Silicon Tandem Modules

4-terminal tandem technology is a straightforward approach to bring to the market perovskite/crystalline silicon tandem modules. However, dealing with 4 terminals poses a challenge at system level for practical deployment. We have produced large area 4-terminal perovskite/crystalline silicon tandem modules for a study of the performance of a 2-terminal voltage matched (2T VM) configuration versus an unconstrained 4-terminal (4T) configuration. The 2T VM configuration is a very interesting proposition to deal in practice with 4 terminal tandem technology at module level. The tandem module assembly consisted of 3 perovskite submodules of 31 cells and 100 cm2 aperture area each, and 3 c-Si submodules of 16 cells and 100 cm2 aperture area each. We have varied the voltage-mismatch from 13% to 42%, by varying the electrically connected c-Si string length. The resulting power loss for 2T VM relative to 4T varied between 4.5% and 20%. We have focused on combining one perovskite submodule with the series connection of the three silicon submodules, using the other two perovskite submodules as optical filter only. We find that the 2T VM power output follows roughly the expected values calculated from the individual characteristics, however, with a 2-3% additional power loss. Analysis of this additional power loss will require precise monitoring of time dependence of I-V characteristics, transmission of the submodules, and other relevant parameters.