The problem of simulated low-velocityudhail impacts on flexible photovoltaic (PV) modulesudresting on a substrate with variable stiffness is investigated.udFor this type of PV module it is shown that theudprescriptions of the IEC 61215 International Standardudfor quality control used for rigid (glass-covered) PVudmodules should be augmented by taking into accountudtheir real mounting condition and the stiffness of theudsubstrate in the simulated hail impact tests. Moreover,udelectroluminescence inspection of the crack patternudshould be made in addition to electric power outputudmeasurements.An implicit finite element simulation ofudthe contact problem in dynamics is also proposed, withudtwo different degrees of accuracy, to interpret theudexperimentally observed extension of cracking.udResults pinpoint the important role of stress waveudpropagation and reflection in the case of soft substrates.
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