May 2024


During recent quality inspections of PV modules at the manufacturing facilities, we identified several key non-conforming findings. As we do every month in this newsletter (and following popular demand), we are happy to share these findings here, along with the corrective measures the factories have implemented to ensure the overall quality of the PV modules.

– Missing Corner Glue After Trimming
This issue arises from the trimming process, where the trimming machine’s blades remove excess glue at the corners of the glass. If the blades are not sharp enough, they may fail to effectively cut off the excess glue, and some glue may be still sticking to the blade. When the blade returns to its idle position, it may inadvertently pull the glue from the corners, creating a gap where no glue is present, and moisture can enter.

Following STS’ findings, the factory implemented several corrective measures. The trimming machine blades replacement schedule was updated. The blade angle was also adjusted to ensure better cutting efficiency and prevent glue from being pulled out during the blade’s movement. Furthermore, employees training was updated, including education on the importance of this issue. Operators should promptly clean any detected glue residue and report any equipment issues to the maintenance department for immediate resolution.

– Ribbon Misalignment on the Backside of the Module
Misalignment of the ribbons/wires on the backside of the modules is another notable non-conformity recently observed. This issue was traced to several factors related to the soldering machine maintenance and operation.

Prolonged use of the soldering machine without proper maintenance may result in the formation of crystal made of flux residues on the v-shaped clamps guiding the ribbon/wires in place for soldering. The ribbons are not maintained in place during soldering, resulting in severe misalignment.

Unfortunately, these defects were not spotted by factory quality control operators because the line was left unchecked during some of the shift rotations.

To address these problems, the factory has implemented several corrective measures. The clamping devices are now inspected weekly, with damaged components replaced promptly. A comprehensive monthly schedule has been established for preventively replacing, cleaning, and repairing all clamping modules. Finally, the factory implemented recurrent training for inspection personnel to ensure thorough and consistent inspections.

– Insufficient Soldering Area
Another common non-conformity is related to a too-short soldering distance where the wires connect to the string busbars.

A root-cause analysis revealed a series of issues. The length of the wires were not properly measured, due to a calibration error; the machine settings were not properly transferred between shifts, leading to inconsistent wire length from one shift to another; and the following quality control check was not properly carried out.

In response to these issues, the factory implemented several corrective measures. The factory conducted additional training focused on process and inspection protocols. The frequency of the inspection of the lamination process was increased: today, 100% of the laminates are inspected. Finally, shift leaders are instructed to regularly reinforce the importance of following standard operating procedures (SOP).