All identifiable faults are detected and recorded by camera during the optical check and cleaning. These include loose junction boxes, faulty cables, deformed frames, cell inclusions and breakages, delamination, visible hotspots and scratches.
The modules are placed in a water bath and 1,000 volts direct current are applied in this test. Only modules that uphold a resistance according to their surface for 2 minutes pass the insulation test. The test criteria comply with the current IEC standards.
The modules are powered backwards during the infra-red test to identify possible weak spots in the cell area, connectors and the junction box by means of the infra-red camera (thermal image).
During so-called “flashing” (acc. to IEC 60904), the module is flashed with a calibrated flasher. the electrical output is measured and the power is determined under standard test conditions (STC).
Damage to the cells can be seen by means of an electroluminescence test. The module is photographed with three high-resolution NIR-CCD cameras at such a high resolution that even the smallest of cracks are detected. The test documentation includes images of the complete module and of every damaged cell.
This technique detects changes in the EVA film caused by UV radiation in the sunlight. With UV fluorescence, it is possible to identify cell cracks and draw conclusions regarding the age of the cracks. This helps to identify the cause of detected damages.
The electrical parameters in accordance with IEC 60904 are measured with a repeating tolerance of +/- 0.8%. The following values can be recorded in the PV Service Center or on site at the system:
- Open-circuit voltage Uoc
- Short-circuit current Isc
- Voltage at the best possible operating point Umpp
- Current at the operating point with maximum output Impp
- Maximum achievable output Pmpp
- Filling factor