Direct Analysis of the Current-Voltage Curves of Outdoor-Degrading Modules

Dirk Jordan, Sarah Kurtz, Carolin Ulbrich, Marzella Goerig, Andreas Gerber, Uwe Rau

Research output: Contribution to conferencePaperpeer-review


We apply a phenomenological four-parameter equation to fit and analyze regularly measured current density-voltage JV curves of various technologies. The physically meaningful four parameters, short-circuit current density Jsc, open-circuit voltage Voc, and differential resistances Rsc and Roc are determined for one-week data intervals of an exemplarily chosen CdTe module during 2.5 years of outdoor operation. For the chosen thin-film module, the fill factor FF degradation outweighs the degradation of Jsc and Voc. Interestingly, the Voc vs. log(Jsc) curves of the module at low irradiation unveil an increasing influence of a double-exponential diode behavior. The data hint at an increasing voltage-dependent charge-carrier collection in CdTe.

Original languageAmerican English
Number of pages6
StatePublished - 15 Oct 2014
Event40th IEEE Photovoltaic Specialist Conference, PVSC 2014 - Denver, United States
Duration: 8 Jun 201413 Jun 2014


Conference40th IEEE Photovoltaic Specialist Conference, PVSC 2014
Country/TerritoryUnited States

Bibliographical note

Publisher Copyright:
© 2014 IEEE.

NREL Publication Number

  • NREL/CP-5J00-61306


  • CdTe
  • degradation
  • diode ideality
  • IV curve
  • monitoring
  • photovoltaic modules


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