| Summary: | 碩士 === 元智大學 === 機械工程學系 === 102 === The vibration reliability testing of solar cell is crucial for the applications of it in the dynamic environment. This study investigates the solar cells when subjected to vibrations at each of the single natural frequencies under the deformation of the corresponding mode shapes, and evaluates their lives based on the resulted attenuation of the photoelectric conversion efficiency.
The study conducted vibration tests of the solar cells with their single edge clamped by using the Scanning Laser Doppler Vibrometer (SLDV). The relating natural frequencies and mode shapes are obtained. It is then proceeded with sinusoidal vibrations of the solar cells under each of their single natural frequencies. These kinds of sinusoidal test will result in the fatigue failure of the solar cell materials and cause the reduction of their photoelectric conversion efficiency. Comparison of the I-V curves before and after vibration can reveal the impact of vibrations on the power conversion efficiency.
Meanwhile, it then uses finite element software (FEM) to conduct modal analysis in determining the relationships between maximum stress and maximum deformation of each mode. By assuming the deformation and stress keep a linear relationship and substituting the obtained displacement results of the SLDV test, the maximum stress under each of the vibration mode can be obtained. If the time sharing ratios of each mode under a random vibration are assumed to be based on a Gaussian distribution, the resulted time duration multiplies the natural frequency can get the cycles of vibration of each mode. Taking the maximum stress and cycle number of each mode and corresponding attenuation of photoelectric conversion efficiency, one can obtain the life under each of the specific vibration modes.
Conclusions of this study can be summarized as the following two points:
The photoelectric conversion efficiency decay by random vibration mostly came from the first mode. Because the stresses of the second and third modes are too small comparing with that of the first mode, their contributions on the overall life calculations are considered as negligible. However, if only a single mode of vibration is taken into account and with the same maximum stress of each mode, the higher frequency modes will cause much decrease on the conversion efficiency. Therefore, when the solar cells are under random vibration excitations, the first mode takes most of the vibration energy, thus considering the first mode is good enough for the life estimation of solar cells.
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