– Wet Leakage Current Test

To evaluate solar module’s insulation against penetration of moisture under potentially wet environmental conditions where the PV system may be installed, manufacturers need to run a wet leakage current test. The way to run the test is to place the module with frame in a shallow tank filled with a conductive solution. The depth of the solution shall be sufficient to wet all the surfaces of the module under test. In case the junction box entries are not designed for immersion, the cable entries shall be thoroughly sprayed with the same solution.

Last month, our inspectors found an instance where the wet leakage current test was not always implemented in accordance with IEC61215. In particular, the junction box entries are neither submerged in the solution nor sprayed thoroughly with the same solution, which may lead to inaccurate measurement of the PV module’s insulation against the moisture or wetness from outdoor conditions.

Different weather conditions like rain, morning dew, fog or melted snow can lead to moisture penetration which can cause corrosion, ground fault and electric shock hazard. The inspection of wet leakage current test is an important requirement.

– Soldering Tensile Test

To qualify the solar cell soldering process, tensile test is on the In-Production Quality Control (IPQC) test check list. STS inspectors found this month a tensile testing machine that was not set to zero when the tensile test was started, potentially leading to inaccurate test results with falsely high tensile test values. Calibration of the tensile testing machine before test is a routine check in our production supervision scope.

Soldering tensile test is the most effective means to monitor the soldering quality, which affects the reliability and service life of the PV modules and is a key point of quality control. As a matter of fact, we regularly see in the field modules installed with poor soldering quality. If the soldering tensile is not calibrated properly, the service life of the PV modules may be reduced, and PV plant performance may not meet expectations. It may also cause problems such as hot spots, and hot spots are a fire hazard.