Crack detection in photovoltaic cells by interferometric analysis of electronic speckle patterns

Tzu Kuei Wen, Ching-Chung Yin*

*Corresponding author for this work

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Cracking is a common problem encountered during the fabrication of crystalline silicon photovoltaic (PV) cells. In this study, electronic speckle pattern interferometry (ESPI) is developed as a tool for rapid identification of cracks in PV cells. Thermally induced cell deformation of defect-free and defect-bearing PV cells was first modeled with numerical simulations and then experimentally studied by optical configuration for ESPI measurement of out-of-plane deformations. Both numerical and experimental results indicate that the speckle patterns imparted during thermal deformation of a cell allow for simultaneous quantification of crack size, location and type in both single- and poly-crystalline PV cells. Speckle patterns near defects were manifested as continuous, chevron-shaped, and broken fringes for scratch, surface cracks, and through cracks, respectively. For comparison to other existing techniques, full field electroluminescent images were also provided for every defective PV cell. Electroluminescent imaging is capable of detecting cracks, but unlike ESPI, is unable to distinguish between the different types of cracks. Because the amount of heating needed to induce out-of-plane deformation resolvable by ESPI is small (<0.5°C) and because ESPI is sensitive to crack type, the ESPI-based imaging study presented here can potentially be developed into a rapid, non-destructive inspection tool for the structural integrity of solar cells at any point within the manufacturing process.

Original languageEnglish
Pages (from-to)216-223
Number of pages8
JournalSolar Energy Materials and Solar Cells
Volume98
DOIs
StatePublished - 1 Mar 2012

Keywords

  • Crack detection
  • Crystalline silicon
  • Electronic speckle pattern interferometry
  • Photovoltaic cell

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