Arc Faults in Photovoltaic Systems

In photovoltaic systems a large amount of electrical connectors has been used in the combination of serial and parallel structures of the modules. Due to the high DC voltages and the aging of the systems, long-lasting arc faults can occur which may cause serious fires. As an initial step to develop sensor-devices for detecting arc faults in photovoltaic systems, a test set-up consisting of several modules, a solar inverter, and a unit for creating artificial arc faults was installed. The analysis of the measured signals in time and frequency domain showed the following: Parallel arcing involves significant changes in the current at the primary side of the converter and is therefore easily detectable. Series arc faults, however, can usually not be detected by a low frequency analysis of current and voltage signals due to the specific characteristic curve of the photovoltaic modules, the control-concept of the converter for maximum power tracking, and possibly changing solar irradiance. Sensors and methods considering the higher spectral components of the arc effects are necessary.