Outdoor PL-Imaging

Contactless PL imaging in the field

To detect faults in outdoor photovoltaic systems there is a need for routine field inspection. Photoluminescence (PL) can provide spatially resolved images of a large variety of loss mechanisms such as recombination, shunts, series resistance, cracks and degradation mechanisms (such as light-induced degradation and carrier induced degradation).

The existing luminescence-based techniques for outdoor inspection are limited to the following

  • the strong ambient sunlight and therefore can only be used at low light conditions
  • require setting-up special hardware for biasing
  • ability to capture image of only one cell at a time

A novel PL-based method is developed that overcomes all the above-mentioned limitations.

The main features of this new method are:

  • It uses the sunlight as the illumination source
  • It provides high quality and high-resolution PL images, even in the presence of strong background sunlight
  • It is contactless: Switching between any two operating conditions is done without changing the electrical wiring of the system
  • It can be used while the modules are installed and under normal operation conditions.
  • Multiple cells can be imaged at once.

Related publications are:

  1. R. Bhoopathy, O. Kunz, M. Juhl, T. Trupke, and Z. Hameiri, “Outdoor photoluminescence imaging of photovoltaic modules with sunlight excitation,” Progress in Photovoltaics: Research and Applications, vol. 26, pp. 69–73, 2017.
  2. R. Bhoopathy, O. Kunz, M. Juhl, T. Trupke, and Z. Hameiri, “Outdoor photoluminescence measurements of photovoltaic modules under full sunlight illumination,” 27th International Photovoltaic Science and Engineering Conference, 2017.
  3. R. Bhoopathy, O. Kunz, M. Juhl, T. Trupke, and Z. Hameiri, “Inspecting series resistance effects and bypass diode failure using contactless outdoor photoluminescence imaging,” World Conference on Photovoltaic Energy Conversion, 2018.