Evaluating the Durability of Balance of Systems Components Using Combined-Accelerated Stress Testing

David Miller, Greg Perrin, Kent Terwilliger, Joshua Morse, Chuanxiao Xiao, Bobby To, Chun-Sheng Jiang, Peter Hacke

Research output: Contribution to conferencePaperpeer-review

2 Scopus Citations


The degradation of photovoltaic (PV) balance of systems (BoS) components is not well-studied, but the consequences include offline modules, strings, and inverters; system shutdown; arc faults; and fires. A utility provider experienced a 30% failure rate in their power transfer chain, originally attributed to branch connectors. Field-failed specimen assemblies were therefore examined, consisting of cable connector, branch connector, and discrete fuse components. In this study, unused field-vintage specimens are examined using combined-accelerated stress testing (C-AST) to clarify the most influential environmental stressors as well as the effect of external mechanical perturbation. A benchtop prototype fixture was used to develop the perturbation capability for the C-AST chamber. The benchtop experiments were also used to develop the in-situ data acquisition of specimen current, voltage, and temperature. A significant increase in operating temperature (100°C from 40°C) and a different failure mode were observed promptly once periodic mechanical perturbation was applied. The current at failure was decreased from 35 A (with failure in the fuses) to 15 A (failure at the male/female metal pin connection). After initial examination using X-ray computed tomography, the external plastic was machined away from failed specimens to allow for failure analysis, including the extraction of the internal convolute springs for morphological examination (optical and electron microscopy).

Original languageAmerican English
Number of pages3
StatePublished - 2022
Event49th IEEE Photovoltaics Specialists Conference, PVSC 2022 - Philadelphia, United States
Duration: 5 Jun 202210 Jun 2022


Conference49th IEEE Photovoltaics Specialists Conference, PVSC 2022
Country/TerritoryUnited States

Bibliographical note

See NREL/CP-5K00-81666 for preprint

NREL Publication Number

  • NREL/CP-5K00-85056


  • balance of systems
  • branch connector
  • C-AST
  • durability
  • DuraMAT
  • fuse
  • reliability
  • SEM
  • XCT


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