SERIS operates a highly specialised mobile daylight luminescence measurement system (“DaySy” from Solarzentrum Stuttgart GmbH, Germany) to provide on-site quality inspection of PV modules and PV strings in broad daylight, without dismantling the modules from the racks. It is a state-of-the-art equipment that enables to capture both electroluminescence (EL) and photoluminescence (PL) images during daytime.
Conventionally, EL and PL measurements have to be conducted under controlled illumination conditions, whereby the PV modules must be removed from the system and brought to an indoor laboratory. However, the new daylight luminescence system DaySy utilizes a noise-cancelling technology based on a synchronized lock-in amplifier to filter out the sunlight while still enabling the camera to detect the infrared emission from the PV modules, even outdoors. Thus, the system can be brought directly to the site for inspection, with the capability to measure the luminescence response of individual modules or even entire PV strings. Furthermore, the system can also utilize the sun as the light source to perform photoluminescence measurements. With these capabilities, various defects such as broken fingers, potential-induced degradation (PID), cracks and micro-cracks in the PV modules/strings can be detected with high throughput.