  Efficient defect detection in solar cell manufacturing is crucial for stable
green energy technology manufacturing. This paper presents a
deep-learning-based automatic detection model SeMaCNN for classification and
semantic segmentation of electroluminescent images for solar cell quality
evaluation and anomalies detection. The core of the model is an anomaly
detection algorithm based on Mahalanobis distance that can be trained in a
semi-supervised manner on imbalanced data with small number of digital
electroluminescence images with relevant defects. This is particularly valuable
for prompt model integration into the industrial landscape. The model has been
trained with the on-plant collected dataset consisting of 68 748
electroluminescent images of heterojunction solar cells with a busbar grid. Our
model achieves the accuracy of 92.5%, F1 score 95.8%, recall 94.8%, and
precision 96.9% within the validation subset consisting of 1049 manually
annotated images. The model was also tested on the open ELPV dataset and
demonstrates stable performance with accuracy 94.6% and F1 score 91.1%. The
SeMaCNN model demonstrates a good balance between its performance and
computational costs, which make it applicable for integrating into quality
control systems of solar cell manufacturing.
