Photovoltaic ground fault detection recommendations for array safety and operation

Abstract

PV faults have caused rooftop fires in the United States, Europe, and elsewhere in the world. One prominent cause of past electrical fires was the ground fault detection "blind spot" in fuse-based protection systems discovered by the Solar America Board for Codes and Standards (Solar ABCs) steering committee in 2011. Unfortunately, while a number of alternatives to ground fault fuses have been identified, there has been limited adoption or historical use of these technologies in the U.S. Analytical and numerical SPICE simulations were conducted for a wide variety of ground faults and array configurations to understand the limitations of fuse-based ground fault protection in PV systems and determine proper trip settings for alternative GFPDs. Simulation results were compared with experimental measurements on arrays to validate the SPICE model as well as provide direction on proper thresholding of residual current detector (RCD), current sense monitor (CSM) and isolation monitor (R iso) devices based on historical fault current data. We argue the combination of simulation results with historical data indicates robust settings are possible for each of these technologies to minimize unwanted tripping events while maximizing PV fault detection.

Fault Diagnostic Methodologies for Utility-Scale Photovoltaic Power Plants: A State of the Art Review

“…Experimental studies were carried out on two PV power plants, under fire due to faults, in the USA. The results indicate that hotspots in protection devices converge in advising the deployment of an insulation monitoring device (IMD) and residual current detector (RCM) devices to prevent fire [70].…”

A comprehensive study of diagnosis faults techniques occurring in photovoltaic generators

“…When a high current passes through the metal parts, the photovoltaic installation must stop since this can generate electrical shocks for users. This is known as ground fault [23,24]. Fig.…”

Review on Methods of Fault Diagnosis in Photovoltaic System Applications

“…For these requirements, it is essential to have practical guidelines and standards for PV system protection to lightning strike threats. A fire hazard in rooftop building integrated PV systems has occurred because of undetected ground faults found in fusebased protection systems [11]. For this reason, a numerical simulation and analytical approach are carried out to investigate the limited utilization of fuse-based ground fault protection.…”

“…Because PV rooftop installations have limited access for inspection and maintenance, a fault diagnostic method for these systems is compulsory in order to avoid potential faults in every section of the installation [10]. Fires in rooftop building integrated PV systems have occurred because of undetected ground faults found in fuse-based protection systems [11]. Therefore, special attention needs to be given to identification of such faults for accurate and immediate responses.…”