Feb 2023


During this month, we identified several non-conformities in the production of PV modules, primarily caused by inadequate work processes and staff operations. These non-conformities have the potential to significantly impact the performance, efficiency, and safety of PV modules both during production and in the field. Here are a few examples:

– Duplicate barcodes on modules were identified as a result of improper rework procedures, which can lead to confusion during inventory management and quality control processes.

– We also observed some cases where solar panels were placed in the wrong area for packaging, and employees did not follow proper procedures for handling them. As a result, these panels fell off their trays and were partially damaged. This damage may or may not be visible by naked eyes, as some shocks may affect the integrity of the fragile solar cells, without obvious damage to the glass or frame.

A damaged PV module can reduce its power output and efficiency, or, depending on type of damage, reduce the useful life of the module. Additionally, a broken solar panel can be dangerous in the field, as its internal electrical parts may be exposed, potentially leading to electrical arcing or even thermal events.

– We found non-conformities when verifying the distance between the cells and the edge of the glass. This was caused by cell strings being moved out of position before encapsulation, or due to the flow of material during the lamination process. Such non-conformity makes the module incompatible with basic safety standards (IEC/UL1730), can significantly increase the risk of electrical arcing and fires, make the module more likely to experience mechanical failures, and decrease its overall efficiency, power output, and lifespan.

– Dents were found on the back of the module, whose origin has been traced to contamination (dust and debris) in the laminator. Standard operating procedures call for regular cleaning of the membrane protective layers; these procedures are not always followed appropriately. Such dent may reduce the insulation properties of the back-sheet, potentially reducing its useful life.

– Severe scratching was observed on the surface of cells during EL imaging testing. This may be due to a defect already present on the cell itself (and therefore not properly filtered during IQC) or damage sustained during module assembly. Scratches on the surface of a solar cell can reduce the surface layer passivation, which can decrease the module overall power output, or create a hotspot. Scratches can also make the surface of the cell more susceptible to corrosion and environmental degradation, which can reduce the module useful life.

– A mismatch in cell characteristics (power and current) was also identified, which can cause the cells to operate at different temperatures, age at different rates and lead to uneven cell degradation over time. This can cause the module to have a shorter lifespan and reduced performance.

When discovered, these non-conformities are immediately addressed and STS oversees the implementation of corrective measures to prevent their recurrence in the future.