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Computer Vision-Based Automated Inspection of Solar Panels using Drone Imagery and Deep Learning

Abstract

Utility-scale photovoltaic farms need inspection methods that can do more than flag a defective panel. The system must identify the defect, locate the affected area, and give maintenance teams enough information to decide which panels require attention first. Drone-based inspection has made large-scale photovoltaic monitoring more feasible, yet many automated models still rely on a single image modality, produce only classification outputs, receive limited robustness testing, or remain weakly connected to maintenance planning. To address these gaps, an explainable RGB-thermal drone-vision framework was developed and validated for localization-aware and severity-ranked solar panel defect inspection in utility-scale photovoltaic farms. The study used 21,500 paired RGB-thermal UAV images collected from operational solar farms over six months. The dataset included seven defect categories and normal panels. Three solar inspection experts annotated the images with bounding boxes, segmentation masks, and severity labels, which allowed the model to be evaluated not only for recognition accuracy but also for spatial localization and maintenance relevance. The proposed dual-branch architecture combines RGB feature extraction, thermal feature extraction, multimodal fusion attention, defect detection, segmentation, severity ranking, and explainability assessment. On the internal test set, the model achieved 96.3% precision, 94.8% recall, 95.5% F1-score, 96.9% mAP@0.5, 83.7% mAP@0.5:0.95, and 84.9% IoU. External validation on an unseen solar farm produced a 92.8% F1-score, which suggests that the model retained good performance beyond the original data collection sites. The explainability module reached 86.7% expert-mask overlap, while severity classification achieved a 92.5% F1-score and maintenance-priority classification reached 94.2% accuracy. Overall, the results indicate that RGB-thermal fusion provides stronger defect detection, localization, interpretability, and maintenance-oriented decision support than RGB-only, thermal-only, and conventional baseline models

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