This Solar America Board for Codes and Standards (Solar ABCs) report addresses the requirements for electrical grounding of photovoltaic (PV) systems in the United States. Solar ABCs, with support from the U.S. Department of Energy, commissioned this report to provide the PV industry with practical guidelines and procedures to ensure reliable PV system grounding as well as the ongoing safety of these systems.
The report explains what grounding is and defines different types of grounding. It also describes existing National Electrical Code® (NEC®) grounding requirements in some detail, explains the basics of grounding PV equipment and systems, and notes the U.S. organizations responsible for developing and publishing grounding and safety standards.
In addition, the report discusses grounding requirements for equipment such as microinverters and AC PV modules, and clarifies the differences between PV system and conventional electrical power systems (utility, generator, or battery sourced) grounding requirements. Finally, it includes an explanation of utility and NEC grounding requirements.
Grounding is a safety issue during the entire lifetime of a PV system, because modules can produce potentially dangerous currents and voltages even if the system is no longer fully functional.
The NEC establishes the legal installation requirements for PV (and other electrical) systems, and the requirements are somewhat complex. This report clarifies some of these complexities and suggests grounding configurations appropriate for PV systems.
PV systems have different grounding requirements than conventional electrical systems, and these differences are not fully addressed in existing hardware standards. As the power output of PV systems continues to increase with each new generation product, grounding is likely to become even more of an issue.
As PV system configurations evolve and new equipment comes on the market, equipment and system grounding protocols may also need to be updated. For example, microinverters and AC PV modules have different grounding requirements than other PV systems.