STS is your “eyes and ears” in the manufacturing lines!

During our recent inspections of PV module manufacturing, we’ve identified a few non-conformities worth sharing. Among them, there are oversized corner gaps in module frames, bubbles at module edges due to insufficient encapsulant, and inconsistent cell alignment caused by material handling and equipment issues.

– Mixed Grading of Cells and Gridline Breakage

During the production of PV modules, it is critical that cells are sorted and aligned correctly according to their power ratings, and that soldering processes are conducted under precise conditions to avoid damage.

Our inspections revealed two non-conformities: mixed grading of cells and gridline breakage. Mixed grading occurred because high and low voltage information was not updated after cell unpacking, leading to mismatched cell groupings. Gridline breakage was linked to excessive soldering temperatures and durations, discrepancies in EL inspection standards, as well as poor exposure settings on the EL testing equipment, resulting in dark images that hindered defect detection.

Mixed grading could lead to uneven module performance, while gridline breakage may compromise electrical conductivity, increasing the risk of hotspots and module failure over time.

To resolve these issues, the factory implemented corrective measures such as verifying cell information before and after unpacking, revising stringer machine parameters to improve gridline integrity, optimizing EL inspector training, and tightening controls on EL equipment settings.

– Corner Gaps in the Module Frame

During PV module manufacturing, frame corners should fit tightly to ensure structural integrity and prevent exposure to external elements.

Our inspections identified a non-conformity where corner gaps in the module frame were larger than acceptable. This issue arose because residual butyl adhesive, left uncleaned on the module edges after trimming, prevented proper frame alignment during assembly. If unaddressed, such gaps could compromise the module’s structural stability and allow moisture ingress, leading to potential long-term degradation.

To address this, the factory implemented measures including training production staff to properly clean NG butyl adhesive before handling modules, scheduling regular cleaning of the trimming machine to prevent adhesive buildup, and enforcing 100% inspection of frame gaps by quality control staff.

– Module Edge Bubbles

During PV module manufacturing, encapsulant should fully cover the edges of the module to ensure a complete seal and prevent air bubbles from forming.

Our inspections revealed a non-conformity where bubbles were present at the module edges due to insufficient encapsulant coverage in some areas. This gap compromises the seal’s effectiveness, increasing the risk of moisture ingress and long-term performance degradation.

To address this, the factory optimized the encapsulant size to ensure consistent edge coverage. Additionally, they implemented a 100% inspection of module edges by cleaning and quality control staff.

Without STS’ on-site inspections, these issues could have gone unnoticed, exposing the modules to quality risks and potential long-term performance issues.