Characterization of Microdamage of Flexible Solar Cell under Fatigue Load using AE and LT Techniques

Flexible solar cells in service are subjected to external load such as thermal expansion mismatch between solar cells and the base. It is considered that microdamage are initiated and accumulated due to those external loads. Some mode of microdamages causing shunt results in the electrical degradati...

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Bibliographic Details
Published in:Journal of acoustic emission 2019-01, Vol.36, p.S112
Main Authors: Matsueda, Takahiro, Wakayama, Shuichi, Nakahara, Kosuke, Takano, Akihiro
Format: Article
Language:English
Subjects:
Acoustic emission testing
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Summary:Flexible solar cells in service are subjected to external load such as thermal expansion mismatch between solar cells and the base. It is considered that microdamage are initiated and accumulated due to those external loads. Some mode of microdamages causing shunt results in the electrical degradation of flexible solar cells. In our previous study, it was revealed that electrical degradation of solar cell is caused by microdamage parallel to the loading direction due to the buckling around through-hole under static tensile loading. The purpose of the present study is to reveal the mechanisms of microdamage initiation and accumulation, and their contribution to the electrical degradation during fatigue fracture.In the present study, cyclic tensile tests performed with the 0.8% and 1.2% maximum strains. Microdamages initiation were detected by the acoustic emission (AE) techniques. The electrical degradation of solar cell was evaluated by monitoring electrical power calculated from Current-Voltage (I-V) curve. Furthermore, microdamages contributing to the electrical degradation were identified by the Lock-in thermography (LT). For the cyclic tensile tests, the first AE signal was detected at the through-holes. Temperature around hthrough-oles increased and electrical power decreased in low cycles. Then AE signals resulted by microdamage initiation were detected each cycles and electrical power was gradually decrease with the increase in the number of cycles until the test stop. It was then indicated that microdamage both of initiating extremely low cycle and high cycle contributed to the electrical degradation. Consequently, it was suggested that the AE, LT and I-V curve monitoring enable to characterize the electrical degradation during fatigue fracture. Keywords: Flexible solar cell, Fatigue, Microdamage, Lock-in thermography
ISSN:0730-0050