The characteristics and microstructure of PV degradation

This paper presents the degradation rate of the PV cells based on their electrical characteristic. The modules used in this study had mono-crystalline silicon (mono-c-si) PV module 53 Wp after over 15 years old of outdoor operation in field conditions. The relation between the physical and electrical of a cell degradation rate on the module had comprehensive analysis. The degradation module is composed of a decrease of natural aging and severe degradation, then selects the representative module of both types. The PV severe degradation will consider the quantity of EVA delamination and corrosion on the busbar. The IV-characteristic was testing at 1000 W/m2 solar irradiance and 25 C module temperature. The microstructure defect and delamination quantity on cells were using Image J and SEM. The electrical results indicated that the degradation rate of maximum output power (Pm) and fill factor (FF) the average value is about 52% and 43%, respectively. The degradation rate of short-circuit current is about 15%. By the way degradation rate of open-circuit voltage is not different. In addition, the parasitic parameter found that the value of the photocurrent (Iph) according to the value of short-circuit current because the current generation of the module has decreased. The value of the saturation current density (I0) and ideality factor (n) is reducing according to an increase in the degradation rate of short-circuit current. In cases of high series resistance (Rs) and low shunt resistance (Rsh) caused by degradation rate of maximum output power and fill factor are increase. The results of the physical obtained indicate that EVA delamination is a non-effect of the current generation. Although the delamination of EVA, the light can also be transmitted into the cell. And the results of the investigation representative cell by SEM found that the green patina and a black of the area on the busbar, maybe corrosion of malachite (Cu2(OH)2CO3) and corrosion of copper (II) (oxide Cu2O) [1,2], the corrosions on the busbar cause the degradation rate to be higher. [3]