Results from an International Interlaboratory Study on Light- and Elevated Temperature-Induced Degradation (LETID) in Solar Modules

Joseph Karas, Ingrid Repins, Karl Berger, Bernhard Kubicek, Fangdan Jiang, Daqi Zhang, Jean-Nicolas Jaubert, Ana Cueli, Tony Sample, Bengt Jaeckel, Matthias Pander, Esther Fokuhl, Max Koentopp, Friederike Kersten, Jun-Hong Choi, Birinchi Bora, Chandan Banerjee, Stefan Wendlandt, Tristan Erion-Lorico, Kenneth SauerJon Tsan, Mauro Pravettoni, Mauro Caccivio, Giovanni Bellenda, Christos Monokroussos, Hamza Maaroufi

Research output: NRELPresentation


This presentation reports recently submitted results from an international interlaboratory comparison study on light- and elevated temperature-induced degradation (LETID) on crystalline silicon photovoltaic (PV) modules. A large global network of PV module manufacturers and PV testing laboratories collaborated to design a protocol for LETID detection, and screen a large and diverse set of prototype modules for LETID. We summarize the range of observed degradation and provide initial conclusions on the reproducibility of results across labs. In LETID-sensitive modules, both open-circuit voltage (VOC) and short-circuit current (ISC) degrade by a roughly similar magnitude. We observe, as do previous studies, that LETID affects each cell in a module differently. An investigation of the potential mismatch losses caused by nonuniform LETID degradation found that mismatch loss is insignificant compared to the direct LETID-related losses. We summarize the conclusions drawn from the study, provide an update on a forthcoming standard technical specification for LETID testing of PV modules (IEC TS 63342 ED1), and discuss unresolved questions and potential future work on LETID in PV modules.
Original languageAmerican English
Number of pages7
StatePublished - 2022

Publication series

NamePresented at the 2022 Photovoltaic Reliability Workshop (PVRW), 21-25 February 2022

NREL Publication Number

  • NREL/PR-5K00-82118


  • degradation
  • photovoltaics
  • PV modules
  • silicon
  • solar cells
  • temperature-induced degradation


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