Thermomechanical Reliability Assessment of Solder Joints in a Photovoltaic Module Operated in a Hot Climate

In this article, the fatigue evolution of solder joints in a photovoltaic (PV) module at a hot climate under thermomechanical cycling was evaluated. The finite-element modeling (FEM) simulation results showed that the degradation evolution is very sensitive to the ambient temperature so that with an increase in ambient temperature from 25 °C to 75 °C, the fatigue life decreased by 34% for the solder joints. A handy equation was also given to predict fatigue life in the mentioned ambient temperature. The simulation outcomes also revealed that with an increase in solder layer thickness, the fatigue life improved, which is due to the lower accumulated strain energy per volume in the solder material. Moreover, SEM micrographs, from the experimental fatigue test, indicated that the damage evolution was accompanied by the appearance of elemental heterogeneity and void coalescence in the solder joints. The X-ray diffraction (XRD) test also showed that the decrease in solder thickness leads to the intensification of intermetallic compounds formation at the interface.