An efficient CNN-based detector for photovoltaic module cells defect detection in electroluminescence images

Electroluminescence (EL) imaging provides a high spatial resolution for inspecting photovoltaic (PV) cells, enabling the detection of various types of PV cell defects. Recently, convolutional neural network (CNN) based automatic detection methods for PV cell defects using EL images have attracted much attention. However, existing methods struggle to achieve a good balance between detection accuracy and efficiency. To address this issue, we propose a novel method for efficient PV cell defect detection. Firstly, we utilize Contrast Limited Adaptive Histogram Equalization (CLAHE) algorithm to improve EL image contrast, making defect features become more distinguishable. Secondly, we propose a lightweight defect detector using EfficientNet-B0 as its backbone. Moreover, we design a graph channel attention module (GCAM) to improve CNN's limitation in modeling global information. It executes graph channel reasoning to generate enriched feature representation beyond the local receptive field, which is beneficial for distinguishing PV cell defects with similar local details. Next, we utilize focal loss to train the detector, enhancing its ability to detect challenging defects. Lastly, the proposed method is evaluated on the PVEL dataset and it achieved an accuracy of 97.81%, precision of 97.70%, recall of 97.59%, F1-score of 97.64%, and MCC of 97.32%, demonstrating our method is effective and outperforms state-of-the-art methods across various metrics.