Abstract Photovoltaic modules are subject to cyclic deformation during their lifetime as a result of vibration, applied loads, and thermal effects. Vibration and applied loads induce cyclic bending on the modules, while operating temperature excursions during the day lead mostly to cyclic axial deformation. In both cases, the region between two solar cells is severely stressed. For cyclic bending, cracks can nucleate near the points where busbars are soldered onto Silicon and might propagate due to fatigue. For cyclic axial deformation, on the other hand, busbars are stressed above the elastic regime and may experience plasticity and hysteretic energy dissipation. The present study focuses on the experimental characterization of such material degradation phenomena related to the above two types of cyclic deformation. For the former, fatigue crack growth in Silicon and its evolution have been quantified by using two independent nondestructive monitoring techniques based on electroluminescence and thermal infrared imaging. For the latter, plasticity and degradation of the material response of busbars has been assessed in relation to different applied cyclic strain levels. The obtained results shed light onto the cyclic response of materials used in photovoltaics, and pinpoint features that should be taken into account in the development of refined standard qualification tests for photovoltaics including cyclic deformation.

中文翻译：

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硅太阳能电池疲劳裂纹扩展和母线迟滞行为

摘要 光伏组件在其使用寿命期间会由于振动、外加载荷和热效应而发生循环变形。振动和施加的载荷会引起模块的循环弯曲，而白天的工作温度偏移主要导致循环轴向变形。在这两种情况下，两个太阳能电池之间的区域都受到严重压力。对于循环弯曲，裂纹可以在汇流条焊接到硅上的点附近成核，并可能由于疲劳而扩展。另一方面，对于循环轴向变形，母线受到高于弹性状态的应力，并且可能会经历塑性和滞后能量耗散。本研究的重点是与上述两种循环变形相关的材料退化现象的实验表征。对于前者，通过使用基于电致发光和热红外成像的两种独立的无损监测技术，已经对硅中的疲劳裂纹扩展及其演变进行了量化。对于后者，母线的材料响应的塑性和退化已经根据不同的应用循环应变水平进行了评估。获得的结果阐明了光伏材料的循环响应，并指出了在开发包括循环变形在内的光伏电池的精细标准鉴定测试时应考虑的特征。母线材料响应的塑性和退化已经根据不同的应用循环应变水平进行了评估。获得的结果阐明了光伏材料的循环响应，并指出了在开发包括循环变形在内的光伏电池的精细标准鉴定测试时应考虑的特征。母线材料响应的塑性和退化已经根据不同的应用循环应变水平进行了评估。获得的结果阐明了光伏材料的循环响应，并指出了在开发包括循环变形在内的光伏电池的精细标准鉴定测试时应考虑的特征。