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Photovoltaic Module Luminescence and Thermal Imaging

DuraMAT's luminescence and thermal imaging capabilities provide pictorial and often intuitive understanding of photovoltaic (PV) module degradation mechanisms.

We can combine several different combinations of module excitation (electrical and optical) and emitted photon detection, resulting in spatially resolved imaging of injection-dependent electroluminescence, contactless electroluminescence, photoluminescence, UV-fluorescence, and lock-in thermography.

Core Objective

Fielded Module Forensics


National Renewable Energy Laboratory (NREL)


The most informative imaging combinations will depend on the type of degradation affecting the module. For example, we are able to create series resistance maps by combining high-injection and low-injection electroluminescence images. Photoluminescence is useful to highlight variations in material quality without dependence on electrical contact. UV fluorescence results from changes in encapsulant chemistry, and it can be a quick method to locate cracks. Lock-in thermography can be useful to identify causes of module heating, such as current crowding, joule heating, defects causing high recombination, and shunting. Comparison of all available images can help to distinguish between various possible degradation modes.


This capability is available to NREL and external collaborators.


Sulas-Kern, D.B.; Johnston, S.; Meydbray, J. “Fill Factor Loss in Fielded Photovoltaic Modules Due to Metallization Failures, Characterized by Luminescence and Thermal Imaging” in 46th IEEE Photovoltaic Specialist Conference (PVSC), Chicago, 2019. 
Sulas, D.B.; Johnston, S.; Jordan, D.C. “Comparison of Photovoltaic Module Luminescence Imaging Techniques: Assessing the Influence of Lateral Currents in High-Efficiency Device Structures” Solar Energy Materials and Solar Cells 2019, 192, 81-87. 
Sulas, D.B.; Johnston, S.; Jordan, D.C. “Imaging Lateral Drift Kinetics to Understand Causes of Outdoor Degradation in Silicon Heterojunction Photovoltaic Modules” Solar RRL 2019, 1900102. 


To learn more about this project, contact Dana Sulas-Kern or Steve Johnston.

Thermal imaging showing most degraded module, medium degraded module, and least degraded module