Design aspects in consideration of hotspot phenomena in high-performance photovoltaic modules featuring different silicon solar cell architectures

Mitigating degradation or failure of high-performance photovoltaic modules due to hotspot phenomena requires the knowledge of the reverse bias behavior of different architectures like the passivated emitter and rear cell (PERC), tunnel oxide passivated contacts (TOPCon), silicon heterojunction (HJT) and perovskite silicon tandem (PVST) solar cells to understand the hotspot response for various module designs with different interconnection layouts of the solar cells. In this study, the current-voltage characteristics of mini-modules featuring one single PERC, TOPCon, HJT or PVST solar cell are measured in forward and reverse bias direction for different shading ratios and a model for evaluating different module designs is established, allowing the prediction of the hotspot temperature of a shaded solar cell in the worst-case scenario of a hotspot endurance test. It is shown that a strong correlation between the solar cell architecture and the module design in terms of maximum hotspot temperature exists. PERC, TOPCon, HJT and PVST solar cells show very different reverse bias behaviors, leading to different hotspot temperatures under various shading ratios whereas HJT and TOPCon solar cells exhibit higher hotspot temperatures than PERC solar cells. Furthermore, it is shown that alternative module designs with a reduced number of solar cells per string and more bypass diodes, but also with parallel substrings, are beneficial in terms of minimizing the hotspot temperature, especially for PVST solar cells which are more susceptible and prone to degradation at high temperatures.