Mechanical fatigue life analysis of solar panels under cyclic load conditions for design improvement

From manufacturing to field operation, photovoltaic modules are subject to dynamic loads. Cyclic load produces dynamic bending moments with tensile and compressive stresses within the solar cells and interconnects. This often leads to fatigue of solar cell interconnects, cell crack initiation, and worsening of pre-existing cracks because of the inherent discontinuity of the metallization. In this paper, a finite element model was performed for the assessment of the module’s deterioration under cyclic load based on the stress-life curves of each material obtained experimentally from other studies. The effect of additional support in contact with the backsheet was also investigated. Results reveal an extension of fatigue life upon the presence of extra support especially in regions with high tensile stresses. The initial stages of the rear aluminum contact deterioration are extended from 790 to 142,700 cycles and from 350 to 8900 cycles for peak stresses of 1000 and 2400 Pa, respectively. The fatigue life of silver busbars and copper ribbons was also improved with the implementation of support. As for silicon, the minimum critical crack length before fracture can be increased by 5 × and 2 × , respectively, in the case of 1000 and 2400 Pa of pressure. The experimental results indicate that the presence of additional support significantly improves the module's resistance to cyclic loads and reinforces the numerical analysis results. The findings of this paper inform on PV module’s degradation during cyclic mechanical loads and provide a descriptive report of the critical areas that are subjected to crack formation and propagation.