Electroluminescence (EL) Imaging
Electroluminescence (EL) imaging is a powerful diagnostic tool used to evaluate the quality and performance of solar photovoltaic (PV) modules. It involves applying a forward bias to the solar cells, causing them to emit light, which is then captured by a high-resolution camera. This technique reveals detailed information about the internal structure and integrity of the solar cells, allowing for the identification of various defects and inefficiencies.
Steps to EL imaging of Solar Cells/Modules
- Forward Bias Application:
A current is applied to the PV module, similar to the current generated during normal operation. This forward bias causes the solar cells to emit light (electroluminescence), which is primarily in the infrared spectrum.
- Image Capture:
A sensitive camera, often an infrared camera, captures the emitted light. The intensity and distribution of the emitted light are recorded to create a detailed image of the solar module.
- Analysis:
The EL image is analyzed to identify anomalies such as dark spots, non-uniform brightness, and other irregularities. These anomalies correspond to various types of defects and inefficiencies within the solar cells.
Types of Defects Detected by EL Imaging
- Microcracks
- Broken Cells
- Defective Contacts
- Degradation Effects
Advantages of EL Imaging
- High Sensitivity
- Non-Destructive
- Detailed Analysis
Applications of EL Imaging
- Manufacturing Quality Control
- Field Inspections
- Research and Development