What is EL Imaging?
The solar cell is at the heart of a solar panel also known as a solar PV module.
Solar PV Cells convert sunlight that falls on their surface to electricity. This is called the Photovoltaic Effect.
Similarly, when electricity is run through the same Solar PV Cells, they convert this energy to light. This phenomenon is called Electroluminescence or EL.
Electroluminescence can only be captured using a specialized camera that has filters that are optimized for sensitivity in the near-infrared spectrum. Something like an x-ray report for humans.
This property of solar PV cells can be used at any stage of their life cycle to look for cracks, defects, and damages in the cells. In fact, technology is available to conduct these tests for solar panels while they are installed at a site!
During the process of solar panel manufacturing, EL imaging is a significant step that allows the panel to be inspected and corrected.
These inspections may reveal defects like micro cracks, insufficient soldering, parts of the cell that are dead (not emitting any light, hence not capable of generating any power), etc.
This testing method is non-destructive, the panel is not affected by the test. EL testing also has the potential to reveal defects that may go undetected using I-V curve tracing and Infrared (IR) scanning.
Apart from manufacturing, EL testing may also be carried out on panels that are to be installed or after installation if they are not giving their expected output.