肖特基旁路二极管在高温反向偏压运行条件下光伏组件中长期耐久性评估

Abstract Even though the bypass diodes in the PV module spend most of their time in the reverse biased condition and often at elevated temperatures, there’s no systematic test/methodology available to assess the impact on their long-term reliability. This paper, for the first time, presents a detailed investigation of the durability of bypass diodes under High Temperature Reverse Bias (HTRB) operation. Ten samples each from four models of commercial Schottky bypass diodes were tested at each of the HTRB test temperatures. All the diodes were characterized using forward and reverse I-V before HTRB testing. HTRB testing was performed at 120 °C, 130 °C and 140 °C, for 1000 h or until all samples failed. These temperatures were chosen such that they were less than the instantaneous thermal runaway temperatures of the diodes being tested. It was found that 95% of the failures that we found happened in the first 6 h of testing and all failures were found to be in short circuit condition. X-ray images revealed excessive pitting on the metallization layer of the diodes. Weibull distribution was found to explain the observed failures and Weibull model parameters were extracted. Arrhenius model fitting to the observed failure data and comparing it with observations from the field and HTRB testing has helped us identify the region where HTRB failures are relevant. Reverse leakage current was thoroughly investigated as a potential signature to predict failure of diodes under HTRB.