Dark Lock-in Thermography Identifies Solder Bond Failure as the Root Cause of Series Resistance Increase in Fielded Solar Modules

Reza Asadpour, Dana B. Sulas-Kern, Steve Johnston, Jenya Meydbray, Muhammad A. Alam

Research output: Contribution to journalArticlepeer-review

17 Scopus Citations

Abstract

Correlating the electrical performance of photovoltaic modules to the spatially resolved photoluminescence, electroluminescence, and dark lock-in thermography (DLIT) images is an important long-Term goal for developing solar cell technology. These images offer highly sophisticated and detailed information about the spatial distribution and (if imaged at successive time intervals) temporal degradation of local series and shunt resistances. There have been extensive studies to correlate these imaging techniques to local characteristics at the cell level. However, it has been difficult to extract and quantify module-level information from the techniques. In this study, we interpret module current-voltage (I-V) measurements along with corresponding DLIT images within a module-scale simulation framework, demonstrating that series resistance degradation of the module I-V characteristics, in this case, can be attributed to solder bond failures. Our simulations highlight how current crowding associated with a failed solder joint (or a section of the solder pad) translates to the characteristic point-like (asymmetric doublet) heating pattern in neighboring solder joints (or the neighboring regions of the solder pad). The correlation between series resistance and solder joint degradation could inform expedited diagnosis of field degradation of solar modules.

Original languageAmerican English
Article number9139421
Pages (from-to)1409-1416
Number of pages8
JournalIEEE Journal of Photovoltaics
Volume10
Issue number5
DOIs
StatePublished - Sep 2020

Bibliographical note

Publisher Copyright:
© 2011-2012 IEEE.

NREL Publication Number

  • NREL/JA-5K00-76185

Keywords

  • Characterization
  • dark lock-in thermography (DLIT)
  • hotspots
  • power dissipation
  • series resistance
  • solder bond failure

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