Silicon-based photovoltaics have experienced rapid growth, recently surpassing 1 TWp of cumulative installed power. Silicon solar cell efficiencies have also risen significantly, with record efficiencies reaching 27.3%, nearing the theoretical limit of 29.4%. Commercial PV modules have achieved efficiencies up to 24.0%. However, the potential for further efficiency improvements in silicon-based PV is nearing its limit. Our thesis explores ways to enhance the efficiency of silicon-based PV modules both under standard test conditions and during long-term field operation.
Our first goal was to analyse losses that occur when scaling from individual cells to entire PV modules. We developed a bottom-up opto-electrical modelling approach which accurately reflects how minor changes on the cell level might affect the overall performance of a PV module. The model was used to examine power loss in solar cells damaged during in-field operation, by modelling four major stress-induced inhomogeneities: contact finger interruptions, active and inactive cracks, and dead cell areas. By calibrating our model, we were able to predict power loss from defects detected by electroluminescence with an error margin within 0.1%. We also found that the extent of damage detected by luminescence imaging strongly depends on the device and imaging optics, which is why we upgraded the model with detailed bottom-up luminesce modelling, which was crucial for accurate edge recombination extraction of cut-cells used in “cut-cell” or “shingled” modules.
Finally, we explored future prospects of the silicon PV technology, focusing mainly on perovskite-silicon IBC-based 3-terminal tandem modules. We demonstrated that properly designed 3T tandem modules could outperform current silicon-based modules and equivalent 2-terminal tandems, which are nearing commercialization. We presented the first experimental realization and outdoor monitoring of a voltage-matched 3-terminal tandem string of significant size, potentially paving the way for future commercial 3-terminal PV modules and potentially drive the efficiencies of silicon-based PV devices beyond 30%.
|