A GFPD plays an important role in a PV system with a DC system ground by helping to prevent fires from ground faults that go undetected by [[Special:MyLanguage/Overcurrent protection device|overcurrent protection devices (OCPDs)]]. A ground fault can go undetected because the OCPDs for the PV source are [[Special:MyLanguage/Wire, overcurrent protection, and disconnect sizing and selection#Phase 3: Overcurrent protection and disconnects|sized to the maximum current of the PV source]], which means that OCPDs are often ineffective against DC ground faults occurring at the PV source as it doesn't exceed their current rating. This can lead to a fire because [[Special:MyLanguage/PV module|PV modules]] will continue to provide current as long as there is sunshine and a circuit. The diagram at right shows how a GFPD operates during a ground fault on an ungrounded DC conductor:
