Table 3 Comparative analysis of ML approaches for photovoltaic defect detection in EL imagery: traditional methods, conventional DL, and ResNet34-Based optimization.

From: ResNet-based image processing approach for precise detection of cracks in photovoltaic panels

Aspect

Traditional ML

Conventional DL

Proposed Method

Input type

Handcrafted features

Raw EL/IR/RGB images

Raw EL images (high resolution)

Feature extraction

Manual engineering

Automatic (convolutional layers)

Automatic via residual blocks with deep feature representation

Model complexity

Low to moderate

Moderate to high

Moderate (ResNet34 strikes balance)

Accuracy

Low to moderate

High

High

Training data requirements

Small to medium datasets

Large datasets

Optimized for medium-sized dataset with class balancing

Generalization

Limited (noise-sensitive)

High (but overfits on imbalance)

High; robust across defect types due to residual learning and augmentation

Computation efficiency

Very efficient

Varies; heavier models (e.g., YOLOv5, ResNet152) require high compute

Efficient; suitable for edge deployment with ONNX export

Detection types

Binary

Binary or multiclass (limited microcrack sensitivity)

Fine-grained (micro/macro, dormant)

Deployment readiness

Offline tools

Resource-intensive

Edge devices (low power)

Robustness to image quality

Low (needs clean input)

Moderate

High due to preprocessing + skip connections in ResNet

Scalability to real-world PV systems

Low

Moderate to high

High (modular, portable)