Prediction of vibration induced damage in photovoltaic modules during transportation: finite element model and field study

The transportation of the photovoltaic (PV) modules involves excessive vibrations and shocks. These dynamic loads can crack the solar cells and glass of the PV modules. The cracks generated in solar cells during the transportation phase may not always have immediate implications on the electrical performance of the PV modules. However, in the long-run, cracks generated during transportation of the modules may propagate during operation in field due to wind load, snow load and thermal stresses. The propagation of cracks may create electrical isolation in the cells of a PV module, which can cause loss of electrical power. Therefore, it is important to minimize the damage in PV modules due to transportation and mechanical handling. In this work, PV modules have been transported in packaging following the industry practices to cover a distance of 270 km with accelerometers attached on several modules. Finite element (FE) modelling has been used to calculate natural frequency of vibration for the assembly of the PV modules by simulating the conditions close to the actual transportation experiment. This study shows that transportation makes the modules vibrate at their natural frequency. The first four natural frequencies of vibration calculated through the FE simulations match well with the peaks observed in the power spectral density profiles experienced by PV modules during transportation. Mode shapes corresponding to the first four natural frequencies have also been visualized to identify the contours with maximum displacement. It is hypothesized that out of all the cells, those falling within the contour of maximum displacement would have higher propensity for damage during the transportation. The results presented here can be useful for PV community to improve the packaging methodology, dimensions and material selection of the photovoltaic modules.