A Defect Formation as Snail Trails in Photovoltaic Modules

In this paper, we discussed the field failures of the brownish discolored lines like snail trails in PV modules. We were successful simulation snail trails in laboratory and outdoor field. We had found out some types EVA (ethylene vinyl acetate) encapsulants and back sheets which had the serious snail trails but others were snail trails free. Furthermore, according to IEC 61215 accelerated aging testing, we also found only within 2% power loss after these modules impacted by snail trails. The main power losses over 5% were come from cell micro cracks before snail trail formation. That snail trails occurrence means solar cells should have micro cracks. In here, we contributed the snail trail effects and avoided the failures in future photovoltaic modules performance.

Residual stress analysis and bow simulation of crystalline silicon solar cells

目的:建立一套系统的方法来模拟矽晶太阳能电池的翘曲行为,进而分析因翘曲而产生的残留应力。创新点:1.利用纳米压痕实验及电子显微镜测量材料性质及结构尺寸,帮助有限元分析更准确地模拟太阳能电池的翘曲行为;2.提出了2个针对不同矽晶太阳能电池因翘曲产生的简易残留应力的计算公式。方法:1.利用纳米压痕实验测量铝胶及银胶的材料性质,使用电子显微镜测量铝胶及银胶的结构尺寸;2.建立非线性有限元分析模型并与实验结果进行比较(图6),得出不同矽晶太阳能电池残留应力分布结果(图7);3.将简易残留应力公式(公式(6)和(7))和有限元分析得到的结果进行比较(图9)。结论:1.建立了一套有效模拟矽晶太阳能电池翘曲行为的分析方法,该方法包含3个部分:(1)纳米压痕实验测量铝胶和银胶的材料性质;(2)电子显微镜测量细部结构尺寸;(3)非线性有限元分析。利用此方法模拟的翘曲行为较其它计算方法更贴近实验结果。2.该方法不仅能分析不同矽晶太阳能电池的翘曲行为,而且能提供除了翘曲以外的其它信息,比如残留应力。本文提出了2个较为简易的残留应力计算公式,计算不同矽晶太阳能电池因翘曲而产生的残留应力。3.该方法考虑了银胶对矽晶太阳能电池翘曲的影响,在实际应用中可以帮助分析不同银胶的网印方式对矽晶太阳能电池翘曲的影响。本文以帮助某公司设计太阳能电池为例,证明了利用该分析方法在实际应用中帮助公司分析银胶网印的可行性。