![]() In order to understand the limitations of fuse-based ground fault protection in PV systems, analytical and numerical simulations of different ground faults were performed. Recently the effectiveness of these protection devices has come under question because multiple fires have started when ground faults went undetected. To mitigate these risks, AC-isolated, DC grounded PV systems in the United States use Ground Fault Protection Devices (GFPDs), e.g., fuses, to de-energize the PV system when there is a ground fault. Ground faults in photovoltaic (PV) systems pose a fire and shock hazard. Further, the measured effects of backfeeding the tripped ground-fault devices for periods of time comparable to anti-islanding allowances for utility interconnection of PV inverters in the United States are reported. This paper discusses the ground-fault issues associated with both the dc and ac side of PV systems and presents test results and operational impacts of backfeeding commercially available ac ground-fault protection devices under various modes of operation. The different dc grounding requirements (country to country) often add more confusion to the situation. This complex arrangement of distributed power and energy sources, distributed more ยป impedance and proximity to other sources of power requires sensing of ground faults and proper reaction by the ground-fault protection devices. PV systems are frequently connected to other sources of power or energy storage such as batteries, standby generators, and the utility grid. Leakage currents associated with the PV modules, the interconnected array, wires, surge protection devices and conduit add up and can become large enough to look like a ground-fault. Stray inductance, capacitance and resistance are distributed throughout the system. ![]() Installed PV systems always have invisible elements other than those indicated by their electrical schematics. Photovoltaic (PV) power systems, like other electrical systems, may be subject to unexpected ground faults.
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