Damage in Monolithic Thin-Film Photovoltaic Modules Due to Partial Shade

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44 Scopus Citations


The typical configuration of monolithic thin-film photovoltaic modules makes it possible for partial shade to place one or more cells in such a module in reverse bias. Reverse bias operation leads to high voltage, current density, and power density conditions, which can act as driving forces for failure. We showed that a brief outdoor shadow event can cause a 7% permanent loss in power. We applied an indoor partial shade durability test that moves beyond the standard hot spot endurance test by using more realistic mask and bias conditions and by carefully quantifying the permanent change in performance due to the stress. With the addition of a pass criterion based on change in maximum power, this procedure will soon be proposed as a part of the module-Type qualification test. All six commercial copper indium gallium diselenide and cadmium telluride modules we tested experienced permanent damage due to the indoor partial shade test, ranging from 4% to 14% loss in maximum power. We conclude by summarizing ways to mitigate partial shade stress at the cell, module, and system levels.

Original languageAmerican English
Article number7523923
Pages (from-to)1333-1338
Number of pages6
JournalIEEE Journal of Photovoltaics
Issue number5
StatePublished - Sep 2016

Bibliographical note

Publisher Copyright:
© 2011-2012 IEEE.

NREL Publication Number

  • NREL/JA-5J00-66491


  • Electric breakdown
  • photovolatic systems
  • photovoltaic cells
  • reliability


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