Sometimes, unusually large numbers of bypass diode failures are seen at PV plants. Often, there isn't any visible signature of the damage, but the diodes are seen to have almost invariably failed in the short circuit condition. Due to lack of any viable explanation, this sort of observation is often blamed on the nearby lightning strikes. However, NCPRE researchers have recently discovered a new vulnerability in the bypass diodes called HTRB, which is detailed in the following paper: Karan P Rane, Narendra Shiradkar, "Long term durability assessment of Schottky bypass diodes in photovoltaic modules under high temperature reverse bias operation," Solar Energy, v. 286, p. 113152, 2025. Our analysis shows that particularly in PV systems that experience recurring partial shading, HTRB may result in diode failures over time. The following figure shows that when the module is partially shaded, the diode will be forward biased, and it will operate at higher temperature - and when the shade is removed, its temperature would begin to reduce, and eventually it will go back in the operating region. However, while doing so, it might spend some time in the HTRB region, and this is where the HTRB damage could accumulate over time. Such recurrences of partial shading events would eventually result in high enough HTRB damage accumulation, leading to the diode failures. Therefore, it is important to assess the vulnerability of diodes in the PV modules against HTRB to determine their robustness to sustain multiple instances of partial shading. Note that this sort of effect is not addressed by any of the tests in the PV module qualification / safety standards available today.