An Improved Hot Spot Mitigation Approach for Photovoltaic Modules Under Mismatch Conditions

Abstract

The reduction of photogenerated current in photovoltaic (PV) cells due to various degradation mechanisms leads to hot spot (HS) generation, resulting in serious safety and reliability concerns. This article presents a novel hot spot mitigation circuit (HSMC), which effectively counters HS formation in cells under mismatch situations, improving the reliability of the entire PV arrangement. The effectiveness of the proposed HSMC is compared extensively with the conventional bypass diode (BPD) through experimentation on a 3×1 PV string and a 3×3 series-parallel (SP) PV array in an outdoor setting. Detailed thermographic analysis showed that the maximum temperature of the PV module under low shading levels reached 119.16% and 54.11% higher with the traditional BPD than with the proposed HSMC when tested on a 3×1 PV string and 3×3 SP PV array, respectively. This indicates that the mismatched cell was subjected to elevated temperatures with BPD. Moreover, the experimental results confirm that the proposed HSMC resulted in enhanced power output and a significant reduction of power loss in the bypass path of the shaded module under increased shading levels compared to the traditional BPD. The proposed HSMC reduced mismatch loss by up to 89.82% when tested on a 3×1 PV string.