Power drop detection in PV string by analyzing I–V characteristics

AbstractPhotovoltaic (PV) systems have been regarded as maintenance-free; however, numerous failures have been reported recently during their operation. These failures not only cause power drops in the PV system but can also lead to serious accidents. This paper proposes a diagnosis method that utilizes the current–voltage (I–V) measurements of the PV string to detect the existence of a power drop module in the PV system. This diagnostic methodology is based on the calculation of the decrease in the area of the string I–V curve and dP/dV–V characteristic from the obtained data. A power drop module in the PV string is assumed and calculated. First, the normal and failed versions of the PV string are distinguished by plotting the decrease in the area of the I–V curve on one axis and the ratio of the power drop on the other axis. The differences among each failure mode are then obtained by evaluating the dP/dV–V characteristic of the PV string. Finally, experimental tests are performed on the PV string to va...