In the requirement of the NEC Article 690.41, there are two
types of groundings in PV arrays. The first one is system
grounding: the PV system with system voltage over 50 volts
should be solidly system-grounded. To achieve that, the
negative conductor usually is grounded via the GFPD in the PV
inverter at point G (see Fig. 1). The other one is the equipment
grounding: the exposed non-current-carrying metal parts of PV
module frames, electrical equipment, and conductor enclosures
should be grounded.