Analysis of electrical and thermal characteristics of PV array under mismatching conditions caused by partial shading and short circuit failure of bypass diodes

• Published in: Energy (Oxford) Vol. 218; p. 119480
• Main Authors: Lee, Chung Geun, Shin, Woo Gyun, Lim, Jong Rok, Kang, Gi Hwan, Ju, Young Chul, Hwang, Hye Mi, Chang, Hyo Sik, Ko, Suk Whan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2021; Elsevier BV
• Subjects: Arrays; Diodes; Failure analysis; Mathematical models; Melting of the junction box; Photovoltaic cells; PV module Heating; PV system Loss; Reverse current; Shading; Short circuit failure of bypass diodes; Short circuits; Simulation; Solar cells; Strings; Surface temperature; Voltage mismatch conditions; Short circuit failure of bypass diodes; Voltage mismatch conditions; Reverse current; Melting of the junction box; PV module Heating; PV system Loss
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2020.119480

In this paper, the problems of PV arrays under partial shading and a short circuit failure of bypass diode were analyzed with modeling the mathematical equation by using simulation, and the electrical and thermal characteristics were analyzed in an outdoor with a module which fabricated assuming a real PV array. The simulation model shows the mismatch current due to a bypass diode failure is proportional to the number of fault diodes and parallel strings in PV arrays. From the results of a field experiment, a reverse current did not flow into the mismatching string under partial shading regardless of system operation status, but the temperature of bypass diode in the case of system operation was 15–23 °C higher than that of the other case. However, in case of the fault bypass diode with the system off, the reverse current of 17A flowed into a fault string. Besides, the surface temperature of fault bypass diode reached above 140 °C, and some solar cells within a fault string was 18 °C higher than normal strings. In this paper, we verified that the short circuit failure of bypass diode creates a mismatch loss in PV system, and the reverse current causes electric-thermal problems in PV array. •The electrical and thermal characteristics of mismatching PV arrays were analyzed.•The reverse current of PV arrays hardly flows due to partial shading.•As the short circuit failure of bypass diode increases, reverse current increases.•Reverse current rise temperature of solar cells and burned out faulty bypass diode.•Monitoring of fuse and bypass diode needs to prevent system output loss and accident.