Impact of Environmental Variables on the Degradation of Photovoltaic Components and Perspectives for the Reliability Assessment Methodology

Michael Kempe, Yadong Lyu, Andrew Fairbrother, Mengyan Gong, Jae Kim, Xiaohong Gu, Scott Julien, Kai-Tak Wan, Sophie Napoli, Adam Hauser, Greg O'Brien, Yu Wang, Roger French, Laura Bruckman, Liang Ji, Kenneth Boyce

Research output: Contribution to journalArticlepeer-review

43 Scopus Citations

Abstract

Backsheet cracking has been a major issue observed in the field; however, standardized qualification tests, such as IEC61215, are inadequate to reliably identify such failures of PV modules due to the lack of the critical weathering factors applied sequentially or in combination, such as those found in the service environments. To address this problem, we investigated the effects of various environmental variables on the degradation and failure behaviors of the polyamide-based backsheet in PV modules retrieved from five different locations, encompassing a variety of climates, including humid subtropical, hot-summer Mediterranean, tropical savanna climate and hot arid. The correlations between the degradation indicators and the weathering variables were further demonstrated by principle components analysis (PCA). We found strong relationships between: carbonyl formation and reflected solar radiation; hydroxyl formation and module temperature; yellowness and NO2 concentration, while no simple correlation could be found between a specific weathering factor and cracking. By introducing additional stress factors to the aged polyamide-based backsheet films with the novel “fragmentation test”, we successfully reproduced the field cracking behaviour. This study has demonstrated that different degradation modes of PV components respond differently to the environmental stresses encountered in service. Thereby, any accelerated laboratory test based on a single set condition or lacking key environmental variables would be inadequate to assess the long-term performance of PV modules and components. A new reliability-based methodology is proposed to quantitatively link laboratory testing with field results for the service life prediction of PV materials.

Original languageAmerican English
Pages (from-to)425-436
Number of pages12
JournalSolar Energy
Volume199
DOIs
StatePublished - 15 Mar 2020

Bibliographical note

Publisher Copyright:
© 2020

NREL Publication Number

  • NREL/JA-5K00-76275

Keywords

  • Backsheet
  • Photovoltaic modules
  • Polyamide
  • Principle components analysis
  • Reliability
  • Weathering

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