Blog

28
Apr 2024

FACTORY FINDINGS

This month, we would like to share with you a few non-conformities on PV module manufacturing and what measures the factories have taken to rectify them and enhance the overall quality assurance processes within their manufacturing facilities.

– Abnormal PID Test Degradation
During lab test of PV module, a concerning non-conformity has emerged regarding the PID (Potential-Induced Degradation) test degradation, exceeding the acceptable threshold of <5%. Investigation revealed that the instability in performance across various batches of cells, coupled with discrepancies in laboratory equipment and testing conditions, have contributed to this abnormal degradation.

Measures have been initiated, including stringent control over the reliability testing of cells to ensure the consistency and stability of raw material quality. Moreover, improved vigilance is being maintained with increased monitoring of reliability tests at the factory, particularly focused on PID tests with varying Bill of Materials (BOM) combinations.

– Residue Adhesive on the Frame
During pre-shipment inspection, a notable non-conformity has been detected concerning residue adhesive on the frame. Investigation into the root causes revealed that the adhesive on the assembly platform was either not cleaned in a timely manner or was not completely removed, leading to the unintended contact of the backside of the frame with the adhesive during assembly. Additionally, both the factory quality and sampling personnel failed to identify the presence of adhesive residue, particularly after junction box soldering and during routine checks in the curing room.

To address this issue, measures have been implemented, including the establishment of clear standards for adhesive cleanliness with regular cleaning intervals every two hours. Furthermore, comprehensive personnel training and skill assessments have been initiated to enhance the identification and inspection of adhesive residue, with a specific directive to inspect modules in the curing room every two hours to ensure adherence to quality standards.

– Wide Gaps Between Frame Corners
A non-conformity has also been uncovered during pre-shipment inspection: wide gaps between frame corners. Investigation into the root causes has revealed several contributing factors. Firstly, the existence of EVA residue within the frame has led to compromised adhesion and subsequent widening of the gaps. Furthermore, the failure to clean up the edge by the chipping edger, coupled with inadequately installed edge tools, has exacerbated the issue. Additionally, there has been a lapse in timely maintenance by production and equipment personnel, further exacerbating the problem.

To address this issue, measures have been initiated. These include comprehensive training for lamination inspection personnel to ensure timely cleanup of EVA residue at the edges and regular checks by equipment personnel on the edging machine.

– Abnormal ratio of A/B potting adhesive
During production supervision, our inspector detected an abnormal ratio of A/B potting adhesive. Investigation into the root causes has revealed a critical issue stemming from the cleanliness and maintenance of the potting machine. Upon immediate cleaning of the glue filling channel and bucket, crystals were discovered in the B glue pipe and bucket, leading to instability in glue output due to crystallization blockage of the hose. Consequently, this resulted in an abnormal ratio of potting adhesive, jeopardizing the integrity of the manufacturing process.

To address this issue, firstly, regular cleaning of the A/B potting adhesive barrel will be implemented to prevent the accumulation of contaminants. Additionally, the equipment maintenance department will be tasked with cleaning and maintaining the hoses of the potting machine for every production run, ensuring smooth and consistent operation.

– Flux Residue in Strings Rework
Another non-conformity uncovered during our inspection is the presence of flux residue in strings rework. Investigation into the root causes has revealed critical lapses in adherence to standard operating procedures (SOP) and inadequate maintenance practices. It was found that rework personnel were not sufficiently familiar with the SOP requirements, leading to the excessive use of flux during the rework process. This excessive flux application resulted in the accumulation of large-scale contamination, making it challenging to remove. Additionally, the neglect of timely replacement of flux in the flux pen and failure to replace the dust-free cloth promptly further exacerbated the issue.

To rectify this critical issue, comprehensive training programs will be conducted to ensure strict adherence to SOP documents and the application of only a small amount of flux during rework processes. Moreover, after completing the repair, personnel will be required to thoroughly wipe the area with a clean lint-free cloth and confirm the effectiveness of the cleaning. Furthermore, a pre-repair inspection will be implemented to check for any flux residue before the string lay-up process.

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