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Thermomechanical Fatigue of Solder Joint and Interconnect Ribbon: Impact of Low Lamination Temperature
D. Lindholm, H.-Y. Li, G. Otnes, G. Cattaneo, S.E. Foss, H. Fjær
Degradation, Modelling / Modeling, Fatigue
Photovoltaic Modules and BoS Components
Subtopic: PV Module Design, Manufacture, Performance and Reliability
Event: 38th European Photovoltaic Solar Energy Conference and Exhibition
Session: 4BO.5.4
622 - 626
ISBN: 3-936338-78-7
Paper DOI: 10.4229/EUPVSEC20212021-4BO.5.4
0,00 EUR
Document(s): paper


Thermomechanical loads constitute an important stressor affecting the durability of photovoltaic (PV) modules. Because materials with very different coefficient of thermal expansion are stacked together at a pre-set pressure and temperature in the module lamination process, typically in the range of 140 to 160 C, stresses are induced in the module assembly after cooldown to room temperature. The purpose of our study was to understand the potential of a lower lamination temperature to reduce thermomechanical fatigue of PV modules, including effects both on the solder bond and the interconnect ribbons. This was done for two different encapsulants, EVA and POE. For this purpose, a three-dimensional FEM model was applied, using a temperature profile that accounted both for lamination and accelerated thermal cycling according to the IEC 61215 standard. With respect to thermomechanical fatigue, results show that a reduced lamination temperature lowers the subsequent thermomechanical stresses experienced both in the interconnect ribbons and the solder joint. Because degradation by means of thermomechanical fatigue of the cell interconnects is typically found among the main degradation modes in photovoltaic modules, our study concludes that a reduced lamination temperature has potential to extend the module lifetime in the field.