Module Tech 04 | EL Inspection Technology

After the advanced technologies like SMBB and high-density encapsulation have been applied in the early production stages, the production process of Gstar's high-efficiency PV modules enters a crucial phase: EL Inspection.

In this stage, inspection equipment uses the principle of the photovoltaic effect to produce high-resolution images of the interior of the cells, precisely analyzing potential defects and ensuring that every module produced by Gstar meets strict quality standards.

During PV module production, defects such as cracks, hidden fractures, and broken busbars inevitably occur, limiting the photoelectric conversion efficiency and lifespan of the module, while also increasing maintenance costs. These defects are often difficult to identify with the naked eye or traditional visible light inspection methods. EL inspection technology, however, reveals even the most hidden defects inside the cells.?

Technical Principle

EL?is called?Electroluminescence, occurs when a forward bias is applied to the cell, causing it to emit near-infrared photons due to radiative recombination of charge carriers. In areas with defects, the light intensity is weaker because of a lower concentration of minority carriers. EL inspection equipment can precisely capture these weak light signals and generate high-resolution images, allowing for real-time observation and accurate localization of defects in the PV module.

Types of Defects Detected by EL Technology

· Cracks: Uneven brightness or visible lines that obstruct current collection, leading to more severe hidden cracks and reduced lifespan.

· Poor Soldering: Abnormal bright or dark spots causing current leakage or short circuits, reducing output power and efficiency.

· Impurities: Bright or dark spots or color differences that hinder photon absorption and transmission, lowering efficiency and potentially causing hot spot effects.

In addition to the above, EL inspection can detect other internal defects such as broken busbars, hidden cracks, broken pieces, cold solder joints, burnt gridlines, black cores, black edges, mixed cells, low-efficiency cells, edge over-etching, PID (Potential-Induced Degradation), attenuation, and hot-spot degradation.

The EL inspection technology used at Gstar's module factories ensures comprehensive inspection of the module's appearance. This allows for timely identification and elimination of potential defects, significantly enhancing product quality and effectively reducing future maintenance costs, providing users with more reliable and efficient photovoltaic solutions.