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

Steven Johnston, Dana Kern, Harvey Guthrey, Lorelle Mansfield, Timothy Silverman, Mowafak Al-Jassim, Elizabeth Palmiotti, Andreas Gerber, Angus Rockett, Jun Liu

Research output: Contribution to conferencePaper


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
Number of pages7
StatePublished - 2018
Event2018 World Conference on Photovoltaic Energy Conversion (WCPEC-7) - Waikoloa, Hawaii
Duration: 10 Jun 201815 Jun 2018


Conference2018 World Conference on Photovoltaic Energy Conversion (WCPEC-7)
CityWaikoloa, Hawaii

Bibliographical note

See NREL/CP-5K00-73714 for paper as published in IEEE proceedings

NREL Publication Number

  • NREL/CP-5K00-70866


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


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