Solar Energy Systems - Grounding Equipment
Grounding equipment provides a well-defined, low-resistance path from your system to the ground to protect your system from current surges from lightning strikes or equipment malfunctions. Grounding also stabilizes voltages and provides a common reference point. The grounding harness is usually located on the roof.
Check with the AHJ – Grounding can be a particularly problematic issue. Be sure to check with the Authority Having Jurisdiction (AHJ) – typically the building department’s electrical inspector – concerning local code requirements.
Equipment Grounding – Equipment grounding provides protection from shock caused by a ground fault. A ground fault occurs when a current-carrying conductor comes into contact with the frame or chassis of an appliance or electrical box. All system components and any exposed metal, including equipment boxes, receptacles, appliance frames and PV mounting equipment, should be grounded.
System Grounding – System grounding requires taking one conductor from a two-wire system and connecting it to ground. In a DC system, this means bonding the negative conductor to ground at one single point in the system. This must be accomplished inside the inverter, not at the PV array.
NEC 2005 and System Grounding – In 2005, the National Electrical Code (NEC) was modified to remove the requirement for system grounding, although your local jurisdiction may not have adopted this revision. The requirement for system grounding was removed to permit transformerless utility-interactive inverters, which have higher efficiency. There are several additional NEC requirements intended to ensure that ungrounded arrays are as safe as grounded arrays, although this is still a point of controversy.
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