Excess Dark Currents and Transients in Thin-Film CdTe Solar Cells: Implications for Cell Stability and Encapsulation of Scribe Lines and Cell Ends in Modules

Research output: Contribution to conferencePaper

Abstract

We have isolated a non-linear, metastable, shunt-path failure mechanism located at the CdS/CdTe cell edge. In such cases, most performance loss, usually erratic, can be associated with the shunt path. We studied these shunt paths using dark current-transients and infrared (ir) imaging and find only one shunt path per cell and only at the cell corner wall, even in badly degraded cells. The effecton diminishing the cell's efficiency far exceeds what would be expected from the cell's linear shunt-resistance value. We propose that current transients and ir imaging be used as a 'fingerprint' of the source and magnitude of excess currents to evaluate the contribution of scribe-line edges and cell ends in thin-film module performance and degradation due to environmental stress. Protectionafforded by, or contamination due to, new or currently used encapsulants can then be evaluated.
Original languageAmerican English
Number of pages7
StatePublished - 2005
Event31st IEEE Photovoltaics Specialists Conference and Exhibition - Lake Buena Vista, Florida
Duration: 3 Jan 20057 Jan 2005

Conference

Conference31st IEEE Photovoltaics Specialists Conference and Exhibition
CityLake Buena Vista, Florida
Period3/01/057/01/05

NREL Publication Number

  • NREL/CP-520-37380

Keywords

  • cell stability
  • cell-ends
  • encapsulation of scribe lines
  • excess dark currents transients
  • infrared imaging
  • module
  • non-linear metastable shunt path
  • PV
  • solar cells
  • thin films

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