Experiment and simulation impulse partial discharge behavior in dielectric encapsulations of field-aged PV modules

Due to PV arrays must install inherently in exposed outdoor location or unsheltered and extended large-surface area, an installation of PV module is necessarily tolerable to direct or indirect lightning strikes without failure during the guaranteed service life time of PV module in the field. The primary aim of this paper is to identify the capability of withstand lightning impulse over-voltage of dielectric encapsulations after degradation in field-aged PV modules. In order to fulfill with the research field of insulating materials for deterioration PV module, the impulse partial discharge from charge release in various defects within the dielectric encapsulation between the edge of solar cells and the frame of PV module have been observed as well. For the simulation, the EMTP software and an electrical model of insulating materials of deterioration PV module was used to simulate the impulse partial discharge behavior. As to the experiment, the PV modules were applied by 1.2/50 μs lightning impulse generator into PV modules. It can be found that a number of ringing frequency trains as oscillations were superimposed on the impulse voltage waveform. Furthermore, the simulated result by EMTP deduced that the ringing oscillations caused by partial discharge in the defects of the degradation PV module. In addition, the partial discharge behaviors within the dielectric encapsulation of the PV module were given for some discussions about relevance of the safety in PV modules and their expected service life time in the field.