Do all good things really come in threes? The true potential of 3-terminal perovskite-silicon tandem solar cell strings

Perovskite-silicon tandem solar cells have now surpassed the 30% efficiency mark, which has led to the acceleration of industrialization efforts. With most research focusing on 2-terminal tandems, we focus our investigation on 3-terminal tandem solar cells, a configuration that promises a higher energy yield under realistic operating conditions. We specifically focus on the simulation of the performance of finite strings of 3-terminal tandem cells interconnected in various voltage-matching configurations. To experimentally validate our string model, we produced, characterized, and modeled a string of twelve 3-terminal perovskite-silicon tandems interconnected in different configurations. The individual tandems of the string have an active area of about 25 cm2 and an efficiency from 24.3% to 27.3% when measured in a 2-terminal configuration. Our findings reveal that 3-terminal tandem strings can outperform their 2-terminal counterparts at the module level already under standard test conditions when selecting a suitable module design (number of cut cells, bifaciality).