The MOV as a Possible Protection Measure for Bypass Diodes in Solar PV Modules

Bypass diode failures have been observed within solar photovoltaic (PV) plants after thunderstorm activity, with no evidence of direct lightning strikes to the PV plant. Previous research has found that bypass diodes are typically weakest in reverse bias, when the reverse current reaches a critical threshold. This paper suggests the use of metal oxide varistors (MOVs) as a potential bypass diode protection measure. MOVs are shown to adequately protect a bypass diode to a level more than double that of where a bypass diode would normally fail, by providing an alternative conduction path for surges induced within a PV installation.