The method of detecting EL hidden cracks in photovoltaic panels during the day

The detection of internal hidden cracks in photovoltaic panels under sunlight during the day can mainly be achieved through the combination of electroluminescence (EL) imaging technology and modern equipment such as drones.

EL imaging technology utilizes the principle of electroluminescence in crystalline silicon to excite fluorescence in defect areas (such as hidden cracks) inside photovoltaic modules under the action of an electric field by applying a forward voltage to the modules. These fluorescent signals belong to the infrared band and cannot be directly observed by the naked eye, but can be captured by high-resolution infrared cameras and displayed in the form of images. Due to uneven electric field distribution, the fluorescence signal in the hidden crack area will be relatively weak, resulting in dark areas or areas with obvious contrast between light and dark on the image, thus achieving the detection of hidden crack defects.

In order to effectively perform EL imaging detection under sunlight during the day, the following measures can be taken:
Using shortwave infrared (SWIR) cameras: SWIR cameras can capture light signals in the near-infrared band, which match the fluorescence signal band generated by EL imaging, thus avoiding interference from sunlight.

Equipped with drones: Drones can carry SWIR cameras and fly above photovoltaic panels to capture images from multiple angles and distances, improving the comprehensiveness and accuracy of detection.

Using special filters and algorithms: Install special filters in front of the camera lens to further reduce the interference of sunlight. At the same time, advanced image processing algorithms are used to process and analyze the captured images, improving signal-to-noise ratio and image quality.

Electrical modulation and post-processing: During the detection process, a modulated voltage signal is applied to the photovoltaic module to generate a more stable fluorescence signal. After the shooting is completed, post-processing is performed on the image, including background subtraction, noise suppression, image stitching, and other steps, to obtain clearer images of hidden defects.

It should be noted that due to the high intensity of sunlight during the day, the signal-to-noise ratio of EL imaging detection may be affected. Therefore, in practical operation, it is necessary to carefully adjust the detection parameters and algorithms to ensure the accuracy and reliability of the detection results. At the same time, the detected hidden crack defects should be promptly processed and repaired to avoid adverse effects on the performance and lifespan of photovoltaic panels.