Degradation of photovoltaic (PV) backsheets is a crucial issue to malfunctions of PV system during their long-term field operations. There is a lack of understanding on the degradation mechanisms of PV backsheets under multiple weathering conditions due to the complexity of the types and sequence of formation of different degradation products. To address this problem, we used the two-dimensional (2D) correlation analysis of infrared (IR) spectra to study the degradation of a typical polyethylene terephthalate (PET)-based PV backsheet, PET/PET/ethylene vinyl acetate (EVA) (PPE), by deconvoluting overlapped bands of different degradation species. The PPE backsheets were exposed to ultra-violet (UV) radiation on the NIST (National Institute of Standards and Technology) SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) at two temperatures (45 °C and 85 °C) in dry condition (relative humidity (RH) ≈ 0%) for 40 days. Outdoor weathering was also conducted at three different sites up to 9 months, comprising a variety of climates, including tropical monsoonal, humid subtropical, and hot arid. The 2D correlation analysis explicitly showed that the PPE backsheets aged at 85 °C under UV not only had faster degradation rate but also had different dominant degradation products compared to the PPE aged at 45 °C. Degradation accelerated at lower 45 °C was found closer to that in field conditions investigated in this work. Therefore, when designing accelerated laboratory experiments, it is important to consider climatic-specific aging parameters for building reliable predictive models for degradation of PV materials.

光伏（PV）背板的降解是光伏系统在长期长期运行过程中发生故障的关键问题。由于不同降解产物的类型和形成顺序的复杂性，对在多种风化条件下PV背板的降解机理缺乏了解。为了解决这个问题，我们使用了红外（IR）光谱的二维（2D）相关分析来研究典型的基于聚对苯二甲酸乙二酯（PET）的PV背板PET / PET /乙烯乙酸乙烯酯（EVA）的降解（ PPE），通过对不同降解物种的重叠谱带进行反卷积。将PPE底片在两个温度（45°C和85°C）的干燥条件下（NIST）（美国国家标准技术研究所）SPHERE（通过高能辐射暴露进行的模拟光降解）暴露于紫外线（UV）下（相对湿度（RH）≈0％）40天。长达9个月的三个不同地点也进行了户外风化，包括热带季风，潮湿的亚热带和炎热干旱等多种气候。二维相关分析明确表明，与在45°C下老化的PPE相比，在85°C下在紫外线下老化的PPE背板不仅具有更快的降解速率，而且具有不同的主要降解产物。发现在较低的45°C下加速降解的程度更接近于这项工作所研究的田间条件。因此，在设计加速实验室实验时，