Thin-Film Module Reverse-Bias Breakdown Sites Identified by Thermal Imaging

Research output: NRELPoster


Thin-film module sections are stressed under reverse bias to simulate partial shading conditions. Such stresses can cause permanent damage in the form of 'wormlike' defects due to thermal runaway. When large reverse biases with limited current are applied to the cells, dark lock-in thermography (DLIT) can detect where spatially-localized breakdown initiates before thermal runaway leads to permanent damage. Predicted breakdown defect sites have been identified in both CIGS and CdTe modules using DLIT. These defects include small pinholes, craters, or voids in the absorber layer of the film that lead to built-in areas of weakness where high current densities may cause thermal damage in a partial-shading event.
Original languageAmerican English
StatePublished - 2018

Publication series

NamePresented at the 2018 World Conference on Photovoltaic Energy Conversion (WCPEC-7), 10-15 June 2018, Waikoloa, Hawaii

NREL Publication Number

  • NREL/PO-5K00-71586


  • accelerated aging
  • breakdown voltage
  • electroluminescence
  • II-VI semiconductor materials
  • imaging
  • photoluminescence
  • photovoltaic cells
  • reliability
  • thermal analysis


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