The mechanical behavior of a photovoltaic (PV) module induced by aerodynamic loads is analyzed in a wind tunnel for three different wind velocities at varied azimuthal and inclination angles. The deformations and flow-induced vibrations of the PV module have been monitored by a displacement sensor. The frequencies of the monitored vibrations are analyzed by Fourier transformation. Finally, the damage potential at cell level caused by wind loads is investigated by electroluminescence. The aim of this work was to study the mechanical transfer behavior of the coupled fluid-structure interaction between the aerodynamic loads and the deformations and vibrations of the module, which is one aspect of the mechanically induced degradation of PV modules.
Temperature cycling tests are part of the IEC 61215 qualification testing of crystalline silicon (c-Si) PV modules for
evaluating PV module degradation caused by the impact of thermo-mechanically induced stresses. The defined
temperature gradient and the cycle time by far exceed the actual impact of natural weathering, however. As a
contribution to comparisons between laboratory testing and natural weathering our work provides data from standard
temperature cycling tests as defined in IEC 61215 and extended from 200 (standard) to 800 cycles. The results of these
tests for seven commercial c-Si PV modules from various manufacturers are compared with results from identical
module types exposed outdoors in different climates for a period of 3 years. Degradation effects are evaluated with
respect to changes in output power, changes in insulation properties and with respect to interruptions in the electrical
interconnection circuits such as cell interconnects. Temperature gradients obtained at the different exposure locations are
used to model the thermo-mechanical stress arising from the mismatches of the thermal expansion coefficients of the
The dynamic behaviour of modules with different designs and sizes is analyzed with different methods. Outdoor measurements
of the deflection show their dynamic behaviour under wind loads and the correlation between wind velocity
and deflection. Indoor tests were performed with acoustic excitation of the modules with monitoring the deflection. Numerical
calculations, based on FEM-modelling, showed that their resonance frequencies are typically in the range from 1
to 100 Hz.
Results of the indoor and outdoor measurements are reported and compared with the numerical results of the FEM-simulation.