Preventing Microcracks in Solar Components: Best Practices from Factory to Installation
In recent days, a distributed photovoltaic investment company has expressed concerns about the quality of photovoltaic components purchased from a certain component manufacturer.
During the incoming goods EL (Electroluminescence) testing, they discovered a defect rate as high as 15%, with severe and fatal defects such as continuous microcracks and tree-like microcracks accounting for 13% of the total. The component manufacturer’s explanation raised questions.
They argued that the testing process did not comply with relevant regulations, asserting that quality inspections should involve the manufacturer’s personnel throughout the process.
Furthermore, they defended the presence of continuous microcracks, claiming that it was within their acceptable standards.
However, the investment company raised valid concerns. They found flaws in the EL test results conducted by the manufacturer before shipping the components.
These flaws included continuous microcracks, tree-like microcracks, black lines on the solar cells, black spots on the solar cells, and snowflake patterns. Even when judged by the manufacturer’s standards, a significant portion of the components could be deemed unsatisfactory.
Despite acknowledging the issues with the initial inspection, the component manufacturer has been slow to take substantive action, causing a delay of several months in the replacement process.
Overall, EL testing before shipping helps to prevent problematic components from leaving the factory. Incoming EL testing helps to trace whether transportation has caused any damage to the components, and completion acceptance EL testing helps identify if construction processes have led to component damage. This approach ensures clear accountability throughout the project’s lifecycle.
From the component manufacturer’s perspective, to mitigate this risk and provide high-quality products to customers, many manufacturers have internal standards for microcracks.
These standards outline specific criteria regarding the type of microcracks, their length, and whether they are continuous. However, the standards for mesh microcracks and continuous microcracks may vary among different manufacturers.
From an industry perspective, this incident serves as a wake-up call, emphasizing the importance of component quality, inspection, and acceptance testing. It pushes component manufacturers to enhance their quality control and after-sales services.
From a company’s standpoint, adhering to incoming goods inspection and completion acceptance testing is a responsibility towards project quality and electricity consumers. Timely detection and resolution of issues through testing can prevent larger safety hazards and economic losses in the future.
A few years ago, microcracks, hot spots, and PID (Potential-Induced Degradation) effects were three significant factors affecting the performance of crystalline silicon photovoltaic components.
In recent years, with rapid advancements in manufacturing processes, equipment, and materials, these issues have been significantly improved. Leading manufacturers can effectively detect and control 100% of microcrack and hot spot defects during the production process, even passing the 192-hour PID test under 85/85 conditions.
However, improper handling, installation, construction, and maintenance, as well as careless stacking of components on-site, can still cause microcracks or damage to the components.
In recent years, with the rapid growth of the distributed market, installation and construction teams of varying levels of expertise, some without systematic training, have become a source of concern.
Microcracks caused by improper handling, transportation, installation, and maintenance have become an increasingly prevalent issue.
To address these problems, it is essential to follow proper procedures at every stage. Factors contributing to microcracks may include:
- During transportation, improper packaging or handling can lead to components pressing against each other unevenly, resulting in microcracks.
- Violent handling during transportation, abrupt vehicle movements, and multiple transfers can also lead to microcracks.
- Inadequate precautions during installation, cleaning, and maintenance can result in microcracks. This includes improper handling of components, stepping on them during installation, or using incorrect cleaning methods.
- Components should be placed on even surfaces. Placing them on uneven surfaces can lead to microcracks.
- Components should not be left exposed or stacked haphazardly at the project site after unboxing.
To mitigate these issues, professional Engineering, Procurement, and Construction (EPC) companies take strict measures to control component transportation, unloading, secondary handling, on-site storage, and installation processes. Here are some key recommendations for controlling microcracks after components leave the factory:
1. Component Placement:
- The area for stacking component boxes should be level and spacious to facilitate transportation and avoid uneven ground that could lead to component microcracks or damage.
- Stacked boxes should not exceed a height of two boxes, and pallets should be arranged evenly to prevent overhang.
- Once components are placed, they should not be moved or relocated repeatedly to reduce the risk of microcracks.
2. Secondary Component Handling:
- After unboxing, components should be transported to the installation site with a two-person lift approach to reduce the risk of dropping or causing vibrations that could lead to microcracks.
- Workers should be vigilant of their surroundings during handling to avoid collisions with other objects that could damage the components.
3. Component Installation:
- Components should be installed from top to bottom.
- During installation, it’s crucial to avoid using bricks, wooden blocks, or other materials to temporarily secure components between each other. Instead, at least two upper bolts should be used for temporary fastening.
- Installers should refrain from standing or placing heavy objects on the components, stepping on them, or subjecting them to impacts that could result in microcracks.
- Bolts used for securing components must be tightened securely, and washers should be level.
For leading photovoltaic companies, it is advisable to provide comprehensive and professional guidance materials, such as on-site component microcrack prevention manuals and videos, to EPC companies, installers, and distributors.
This information is especially important for distributed projects, as stakeholders in these projects may have limited expertise compared to experienced EPC teams handling large-scale ground-mounted installations.
It is the responsibility of leading photovoltaic companies to offer detailed guidance services to ensure the quality of their products is maintained throughout the entire project lifecycle.