Test content
Routine testing includes assembly process quality inspection and performance safety testing. The quality inspection of assembly process mainly checks the appearance quality, including the welding quality of the surface of the solar panel, the serial and parallel connection points, and the bonding quality of the packaging board.
Visual inspection and optical instruments can be used for ordinary inspection, as well as infrared emission method, acoustic emission method, infrared microscope, and holographic technology to detect the welding quality. Performance safety testing includes electrical performance testing, withstand voltage insulation testing, mechanical load testing, hail testing, fire testing, etc.
Raw material testing
Before entering the solar module workshop, all raw materials must undergo visual inspection; Glass panels need to be tested for light transmittance, etc; The back panel needs to be tested for tensile strength, permeability, breakdown voltage, etc;
EVA needs to be tested for light transmittance, breakdown voltage, peel strength from the back panel glass, and peel strength from the back panel glass after aging; Welding strips need to be tested for tensile strength, electrical resistivity, etc;
Silicone needs to be tested for curing rate and peel strength from the back panel; The junction box needs to be sampled for fire resistance testing, conductivity testing, etc. Only raw materials that pass all inspections can enter the production line.
Production line testing
The solar panels are formed by single and series welding to form a battery string, which is then arranged in sequence with glass, EVA, and backboard for lamination.
Before laminating solar modules, a visual inspection is required to ensure that the welding rods do not break or fall off, the position of the solar cells is correct, the stacking order and size meet the requirements, and there are no debris between the layers.
After passing the appearance inspection, perform pre lamination EL testing. The components that pass the appearance inspection should be subjected to EL testing after lamination using an EL tester. The brightness of each solar cell should be uniform, with no obvious shadows or excessive brightness.
Through this test, it is ruled out that the lamination process may cause damage to the battery cells. To ensure the quality of lamination, regular peel strength tests are required.
Laminate the sample solar module (without solar cells) and the normal solar module together, and then measure the tension required to peel off EVA and glass, EVA and backplate. After replacing the raw materials of solar modules or adjusting the process, an additional peel strength test is required.
Final assembly testing
The final assembly includes the installation of the solar module frame and the installation of the junction box. Before starting work on each shift, it is necessary to conduct a torque test on all drivers used in the final assembly process to ensure that the installation tools are in normal condition.
After final assembly, the solar modules are first visually inspected to ensure that the dimensions are correct, the junction box position is correct, and the glass and back panel are undamaged. The solar modules that pass the appearance inspection enter the curing chamber and are cleaned after curing for the specified time.
At the same time of cleaning, use a multimeter to check the grounding continuity of the cleaned solar module, ensuring that the frame of the solar module can be well grounded. After cleaning, use an insulation withstand voltage tester for high-voltage testing.
Apply a certain voltage between the frame and electrode leads to test the withstand voltage and insulation strength of the solar module, ensuring that the solar module is not damaged in unexpected situations (such as lightning strikes).
Before entering the next process, a sample should also be taken for the insertion and extraction force test of the junction box lead end. This test uses a tension meter to check whether the leads fixed by the junction box can withstand the specified tension, ensuring that the connection between the solar cell string and the junction box has sufficient strength.
Before packaging, it is necessary to conduct electrical performance testing and EL testing on the solar modules. The electrical performance test mainly tests the performance of solar modules, such as open circuit voltage, maximum short-circuit power, and filling factor, and labels the test results on the back of the solar modules.
Due to the significant physical impact on the solar modules during the final assembly process, there is a high possibility of hidden cracks in the solar cells. Through EL testing before packaging, the problem with the solar modules has been ruled out and qualified parts have been packaged.
According to the electrical performance (power or current) of solar modules, they are packaged and labeled in different levels. After passing the appearance inspection of the packaging, they are stored in the warehouse.
