In-Situ Measurement of Power Loss for Crystalline Silicon Modules Undergoing Thermal Cycling and Mechanical Loading Stress Testing

Sergiu Spataru*, Peter Hacke, Dezso Sera

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

12 Downloads (Pure)


An in-situ method is proposed for monitoring and estimating the power degradation of mc-Si photovoltaic (PV) modules undergoing thermo-mechanical degradation tests that primarily manifest through cell cracking, such as mechanical load tests, thermal cycling and humidity freeze tests. The method is based on in-situ measurement of the module’s dark current-voltage (I-V) characteristic curve during the stress test, as well as initial and final module flash testing on a Sun simulator. The method uses superposition of the dark I-V curve with final flash test module short-circuit current to account for shunt and junction recombination losses, as well as series resistance estimation from the in-situ measured dark I-Vs and final flash test measurements. The method is developed based on mc-Si standard modules undergoing several stages of thermo-mechanical stress testing and degradation, for which we investigate the impact of the degradation on the modules light I-V curve parameters, and equivalent solar cell model parameters. Experimental validation of the method on the modules tested shows good agreement between the in-situ estimated power degradation and the flash test measured power loss of the modules, of up to 4.31 % error (RMSE), as the modules experience primarily junction defect recombination and increased series resistance losses. However, the application of the method will be limited for modules experiencing extensive photo-current degradation or delamination, which are not well reflected in the dark I-V characteristic of the PV module.
Original languageEnglish
Article number72
Issue number1
Number of pages16
Publication statusPublished - 2021

Bibliographical note

This article belongs to the Special Issue: 'Solar Hybrid Power Systems'


  • Photovoltaic modules
  • Accelerated stress testing
  • In-situ monitoring
  • Dark I-V curves
  • Thermal cycling
  • Mechanical loading
  • Degradation monitoring

Fingerprint Dive into the research topics of 'In-Situ Measurement of Power Loss for Crystalline Silicon Modules Undergoing Thermal Cycling and Mechanical Loading Stress Testing'. Together they form a unique fingerprint.

Cite this