Characteristics of Failure Schottky Barrier Diode and PN Junction Diode for Bypass Diode using Induced Lightning Serge Test

In a solar power generation module, when a bypass diode (BPD) with a resistance ranging between 0.1-10 Ω is damaged by a lightning surge, a circulating current flows through the bypass circuit comprising a serially connected BPD and solar cell. In such a case, the BPD is in danger of heating up and catching fire. In this report, Si Schottky barrier diodes (SBDs) are widely used as BPDs in solar cell modules and PN junction diodes (PNDs), characterized by larger reverse breakdown voltages as compared with SBDs. Herein, we report on the fault characteristics dependent on lightning-induced voltage. We find that the risk of heat generation and burning increases if SBDs and PNDs break down owing to lightning with a relatively small amount of electric charge. Thus, it became clear that the failure of an SBD laps into a failed state more easily, which can cause heat generation and burning, as compared with PND.