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Drivers for the cracking of multilayer polyamide‐based backsheets in field photovoltaic modules: In‐depth degradation mapping analysis
Progress in Photovoltaics ( IF 6.7 ) Pub Date : 2020-03-09 , DOI: 10.1002/pip.3260
Yadong Lyu 1 , Andrew Fairbrother 1 , Mengyan Gong 1 , Jae Hyun Kim 1 , Adam Hauser 2 , Greg O'Brien 2 , Xiaohong Gu 1
Affiliation  

There is a lack of understanding on the root cause of cracking of photovoltaic (PV) backsheets due to the challenge of multilayer characterization and the complicated failure modes at the submodule level. In this work, the in‐depth degradation mapping of field‐exposed polyamide‐based (PA‐based) PV module backsheets was studied, with the major focus on the identification of underlying drivers for the through cracking (in between the solar cells). PV modules were retrieved from five different locations, comprising a variety of climates, including humid subtropical, hot‐summer Mediterranean, tropical savanna climate, and hot arid. A suite of microscale cross‐sectional characterizations, including chemical changes, fluorescence intensity, and modulus as a function of distance from the air surface of the backsheet, was performed. Results showed more advanced signs of degradation of the inner layer than the outer layer in the cracking region. Increases in the modulus were identified as the major indicator for the cracking. Moreover, a rudimentary test by immersion in acetic acid, which forms during photodegradation of the ethylene‐vinyl acetate copolymer (EVA) encapsulant, showed the first‐time direct evidence that acetic acid can largely accelerate the chemical degradation and facilitate the cracking of PA inner layer. This study suggests that the field cracking of PA‐based backsheet can be attributed to the combined effects of chemical degradation and physical reorganization (chemi‐crystallization) under cyclic thermomechanical stresses. Therefore, it is important to consider effects of local microclimates and interlayer infection to understand the heterogeneous nature of backsheet failures.

中文翻译:

现场光伏模块中多层聚酰胺基背板破裂的驱动因素:深入的降解图分析

由于多层表征的挑战以及子模块级别复杂的故障模式,因此对光伏(PV)背板开裂的根本原因缺乏了解。在这项工作中,研究了现场暴露的聚酰胺基(PA基)PV组件背板的深入降解图,主要侧重于确定贯穿裂纹(在太阳能电池之间)的潜在驱动因素。从五个不同的地点检索了光伏组件,这些地点包括多种气候,包括亚热带湿润,地中海夏季炎热,热带稀树草原气候和干旱热。进行了一系列的微观横截面表征,包括化学变化,荧光强度和模量与背板空气表面距离的函数。结果表明,在裂纹区域内层的降解迹象要好于外层。模量的增加被确定为开裂的主要指标。此外,在乙烯-乙酸乙烯酯共聚物(EVA)密封剂的光降解过程中,通过浸入乙酸中进行的初步测试表明,乙酸是首次直接证据,表明乙酸可以大大加速化学降解并促进PA内部的开裂。层。这项研究表明,基于PA的背板的现场开裂可归因于循环热机械应力下化学降解和物理重组(化学结晶)的综合作用。因此,
更新日期:2020-03-09
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