Failure Analysis of PV Modules

Failure analysis of cell cracks
© Fraunhofer CSP
The dark discolorations on solar modules often known as »snail trails« (left) and their matching cracks in the solar cells (right) are central issues of status analysis.

The status analysis of solar modules is a central assignment in the scope of the reliability and service life assessment of solar modules and in the evaluation of field returns. To this end, we offer a comprehensive range of performances so we can respond to individual customer requests.  


  • Electroluminescence
  • Thermography
  • Performance measurement of solar modules in conformity with IEC 61215:2016
  • Disassembly of solar modules for error analysis
  • Light microscopy of solar modules for error analysis
  • Open-field performance evaluation
  • Isolation test in conformity with IEC 61215:2016 MQT 03
  • Wet leakage current test in conformity with IEC 61215:2016 MQT 15
  • Hot-spot endurance test in conformity with IEC 61215:2016 MQT 09


quasi-static universal testing machine
© Fraunhofer CSP
The quasi-static universal testing machine simulates the effects of mechanical loads such as snow or wind on solar modules and components.

Mechanical Characterization

Solar modules must be able to withstand a number of external loads such as wind, snow and temperature changes. These loads cause high stresses in the components of the solar modules and can lead to damage and defects. Thanks to comprehensive competences in the mechanics of materials, we are able to systematically investigate the behavior of solar modules and module components.

Elektrolumineszenz-Aufnahme PID
© Fraunhofer CSP
Electroluminescence image of a solar module affected by PID.

High Voltage Stress Test (HVST) and Potential Induced Degradation (PID)

In recent years, in installations with high system voltage and transformerless inverters there has increasingly occurred a degradation of solar modules whose cells have a high negative voltage across the earth. This effect is called potential induced degradation (PID). The observed power degradation at PV power plants can be more than 30 percent. With increasing permissible system voltage up to 1500 V and the development of equatorial sites for solar power generation, it is to be assumed that this effect is going to be gaining in importance.

hot-spot detection
© Fraunhofer CSP
Using electroluminescence studies, it is possible to identify the electrically active and less active regions in the module (left). Thermographic methods (right) also enable hot-spot detection.

Electroluminescence and Thermography Investigations

Destruction-free methods are usually the beginning of an error analysis. They allow the classification of defects with respect to electrical relevance and a first assessment of the nature of the defect. Lastly, a first localization of the defect origin is possible.
Electroluminescence, for example, allows to distinguish between the electrically active and less active regions in the module (for example as a result of cell breakage, connector breakage, light degradation) and to investigate parallel resistance problems (for example as a result of PID, short circuits, light degradation).
Thermographic methods also enable identification of series resistance problems and hot-spot detection.