Grounding system sizing and selection

Properly grounding all non-current carrying metallic equipment in the electrical system, as well as both the AC and DC side of a PV system, is recommended to help mitigate electrical fires, lighting and electrocution risks to system users. This is no easy task though as designing and installing a proper grounding system is one of the more complicated aspects of off-grid PV system design as there are many different components that are required in order for a grounding system to function properly. The appropriate design varies regionally based upon not only the electrical code, but also the building, soil type and available materials.

Step 1: Determine the type of grounding electrode

Determining the right grounding electrode for a particular project is best done by consulting local electricians. There are some general principles with regard to choosing a grounding electrode:

Type	Description
Ground rod	Ground rods are driven into the ground - typically with a hammer. They must penetrate 2.5-3 m of ground in order to be able to establish a solid connection with the earth, which can be extremely difficult to achieve in rocky soil.
Ground plate	In locations where
(3) Charge controller output circuit	= Current rating of the charge controller
(4) Charge controller load circuit	= Current rating of the charge controller lighting/load circuit
(5) DC branch circuit	= Sum of all loads on the circuit from the DC load evaluation.
(6) Inverter input circuit	= Final inverter continuous duty rating ÷ Low voltage disconnect parameter ÷ Inverter efficiency parameter
(7) Inverter output circuit	= Final inverter continuous duty rating ÷ Inverter AC voltage
(8) AC branch circuit	= Sum of all loads on the circuit from the AC load evaluation.
(9) Energy storage circuit	= Larger of Inverter input circuit current or Charge controller charging circuit current