Due to outdoor exposure, photovoltaic (PV) modules are subjected to degradation phenomena during their expected lifetime (20–25 years). Producer warranties claim power losses lower than 10% of the initial nominal power during the first 10–12 years, and up to 20% after 20–25 years of operation, with different power loss rates.¹ Many external sources of stress, like solar radiation, wind, high temperature excursions, moisture, hail impacts, vibrations, fatigue, etc. contribute to PV damage.^1–7 PV degradation manifests itself as a gradual deterioration of materials and components, affecting the optimal working conditions.^8,9 As a result of that, electrical performances might decrease over time. In addition to this, safety issues are also related to material and component degradation. Conventionally, a relevant degradation occurs when the PV power output drops below 80% of its initial value,² while the excess of degradation over a threshold specified for each failure mode could be critical for PV operation.¹⁰

中文翻译：

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无损监控光伏模块加速老化所造成的损坏

由于暴露在室外，光伏（PV）模块在其预期寿命（20-25年）内会发生降解现象。生产者保修要求在最初的10–12年内，功率损耗低于初始标称功率的10％，在运行20–25年后，功率损耗高达20％，且功率损耗率不同。¹许多外部压力源，例如太阳辐射，风，高温偏移，湿气，冰雹撞击，振动，疲劳等，都会造成PV损坏。^1–7 PV退化表现为材料和组件的逐渐退化，影响了最佳工作条件。^8,9结果，电性能可能随时间降低。除此之外，安全问题还与材料和组件的退化有关。常规上，当PV功率输出降至其初始值的80％以下时会发生相关的降级^2，而对于每种故障模式而言，超出指定的阈值的降级过量可能对PV操作至关重要。¹⁰