EL tester, detecting "defects" in PV modules

The components of a photovoltaic module consist of photovoltaic glass, cells and backsheets, which are tightly bonded by an adhesive film, with an aluminium frame to provide additional stability. The cell, the core of the module, is a fragile structure. When subjected to external forces such as treading, impact or vibration, the cells may develop imperceptible cracks or simply shatter. Such damage will reduce the power output of the module and may cause safety problems. However, such defects cannot be seen by the naked eye, so professional instruments are needed to do a good job of testing the quality of PV modules.

The EL tester uses the principle of electroluminescence to make solar cells emit light by applying a positive current of 1-50mA to them. The signal is then captured by an imaging system and transmitted to computer software for analysis, ultimately displaying an EL image of the cell on the screen. The brightness of this image is proportional to the electron diffusion length and current density. By analysing the EL image, it is possible to effectively detect the presence of problems such as cracks or breakage in the PV module.

Faults such as black spots, internal cracks (hidden and visible), cell quality issues, and poor soldering in solar modules can be visually detected using EL testers, allowing for quick identification of defective modules. This inspection technology is essential for improving power generation efficiency and ensuring continuity and stability of production. By conducting rigorous inspections at an early stage, the overall quality of the plant can be effectively controlled, reducing possible performance degradation, power output deficiencies, and associated liability and maintenance issues at a later stage. Therefore, the electroluminescence tester for solar cells plays an extremely important role in the operation and maintenance of solar power plants.