The fault scenario could be explained with the help of I-V
characteristics analysis in Fig. 3, in which Voc is the open circuit voltage of one PV module. Before the fault, the PV array
is working at MPP with operating voltage Vmpp and operating current I
mpp. At the moment of the ground fault, the PV array’s
configuration and I-V characteristics are changed suddenly. Meanwhile, the operating voltage at Vmpp is dropping to VF
immediately. Since VF is the open-circuit voltage of the faulted
array, the array becomes open-circuit and there is no current
feeding into the PV inverter.