Recently, a screenshot of a circle of friends exploded in the photovoltaic industry , and a distributed photovoltaic investor complained in the circle of friends that the components of the head component manufacturer had major quality problems. According to the content of
the circle of friends, after the components arrived, the investor carried out EL testing on the corresponding components. The results showed that 15 of the 100 randomly sampled components had defects, and 13 of the 15 had serious and fatal defects such as penetrating cracks and tree-like cracks. The test report is attached
here:
In this test report, the cause of Class D defects is attributed to the process problems of the cell or component itself. EL defects, such as broken grid, black spot, mixed block , etc.
In the follow-up, the investor mentioned that after discovering the quality problems of the components, the manufacturer of the components insisted that there was no problem when the batch of components left the factory, and the investor did not have the presence of the manufacturer's personnel when t esting, which did not conform to the process; On the other hand, penetrating cracks are allowed in enterprise standards, and the cracking rate of components is in line with the standards when they leave the factory. The
two sides pulled until the investor found that there were many defects in the components before delivery from the factory EL test photos, and then the component manufacturer relaxed the replacement.
However, the replacement has not been in place until now, but has begun a new round of long delays.
In fact, this is not the first manufacturer to be exposed to the problem of component cracking. As one of the three major factors affecting the performance of components, battery cracking was once called the three killers of components together with hot spots and PID. Before 2018, there was even a discoloration of "cracking".
So what exactly is a crack?
Hidden cracks, as the name suggests, refer to the small cracks that appear in the component cells under the action of external forces. Cracks can occur in the production process of components, and may also occur in the transportation and installation process of components. According to the shape,
the cracks can be simply divided into six types: tree cracks, comprehensive cracks, + 45 °/-45 ° (oblique cracks), cracks parallel to the grid line, cracks perpendicular to the grid line, and cracks throughout the entire cell.
These cracks lead to the failure of the cell in this area by blocking the collection of current. The more cracks, the larger the possible failure area. When the failure area reaches a certain level, it will have a greater impact on the power generation efficiency of the module.
However, as the manufacturer mentioned above said, because not all hidden cracks will cause serious consequences, the hidden cracks parallel to the main grid line are the most fatal, followed by 45 ° oblique cracks, the degree of injury is about 1/4 of the parallel main grid cracks, while other types of hidden cracks have little impact.
Therefore, as long as the components meet certain standards in the factory EL inspection , they are qualified .
In a media article in 2017, Xu Hailiang, then vice president of TUV Nande Group in Greater China, said, " All components have cracks, but not all cracks will affect the efficiency of power generation.". "For the fear of cracks on the market at that time, he pointed out that" there are many causes of cracks, which can occur in the production, packaging, storage, transportation, installation, operation and maintenance of components, but the cracks that generally affect the efficiency of power generation are mainly in transportation and installation, especially in the process of improper construction, as long as they are in the process of transportation and installation. There is no need to worry about the crack problem.
Previous studies have shown that when the failure area of a single cell in the module is less than 8%, it has little effect on the power of the module, and 2/3 of the diagonal stripes in the module have no effect on the power stability of the module.
For the industry at that time, cracks were inevitable, but after several years of technological development, the identification of cracks, hot spots, PID and other defects in the production process has made significant progress. In particular, the first-line enterprises have been able to achieve 100% crack identification in the production process of components.
But identification and avoidance are two different things, in the matter of whether the hidden crack components can be shipped, each enterprise has its own corresponding factory standards , involving the length of the hidden crack, type, penetration or not. But now, this standard is not uniform, which also means that it is very easy to cause cognitive confusion downstream, this defect is qualified for manufacturer A, and another manufacturer is not qualified.
It is no wonder that the head manufacturer explained that the batch of components met the factory requirements.
Therefore, from the perspective of the future, whether the components involved are qualified or not can only depend on the introduction of unified standards in the future. Now, naturally, the public is right and the mother-in-law is right.
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