BC Cell Sorting Machine: The 'Precision Sieve' for Back-Contact Technology

　　In the wave of photovoltaic technology iteration, Back Contact (BC) cells are becoming a new favorite in the high-end market due to their advantages such as front no gate lines, high conversion efficiency, and excellent aesthetic characteristics. The key to achieving high efficiency and high-quality production of BC batteries is the highly specialized BC battery cell sorter. It is like a precise "quality inspector", conducting precise performance "physical examination" and grading of each BC battery to ensure that high-performance battery cells are accurately identified and reasonably applied. It is the core equipment for the commercialization of BC technology.

　　The special challenge of BC battery sorting

　　The structural characteristics of BC batteries pose unique challenges for their sorting, far exceeding conventional battery cells:

　　The electrode structure is complex: all positive and negative metal contacts are precisely arranged on the back of the battery, forming a complex electrode pattern. The sorter needs to accurately locate and contact these small, dense electrode points (such as dots or slender strips) to ensure the accuracy and stability of electrical performance testing, and avoid poor contact or damage.

　　No front grid line obstruction: The absence of front grid lines means higher optical utilization, but also imposes strict requirements on the light avoidance of the test probe, and it is necessary to minimize the measurement deviation caused by optical obstruction during testing. The BC cell sorter requires a specially designed ultra-fine, low shadow probe system.

　　High efficiency and high precision requirements: BC batteries typically represent the industry's top efficiency level (>25%), and small differences in their electrical parameters (especially low current levels) correspond to significant efficiency ratings. The sorter must have extremely high measurement accuracy (current measurement uncertainty usually needs to be<0.5%) and stability in order to achieve fine grading (such as 0.1% efficiency interval).

　　Difficulty in appearance inspection: Although the uniform dark color appearance on the front is beautiful, it also makes some minor defects (such as extremely fine scratches, dirt, color differences) more difficult to detect by traditional visual systems, requiring higher resolution and more advanced imaging algorithms. The BC battery cell sorter needs to have stronger visual inspection capabilities.

　　The core technology composition of BC battery cell sorter

　　To address the above challenges, modern BC battery cell sorting machines integrate multiple cutting-edge technologies:

　　High precision, low shadow electrical performance testing system:

　　Specialized low shadow probe card: using a precision designed probe array, the probe head is extremely small and has a special light blocking structure (such as black coating, specific angle), ensuring precise and reliable contact with the back electrode while minimizing the obstruction of front incident light (shadow loss is usually<0.5%).

　　Ultra precision Source Measure Unit (SMU): Provides highly stable voltage/current sources and performs current and voltage measurements with nanoampere level accuracy, particularly adept at capturing the subtle characteristics of BC cells in low light or low current areas (near open circuit voltage).

　　Spectral Adjustable Solar Simulator: Provides A+level spectral matching, spatial uniformity, and temporal stability simulation light sources that comply with international standards such as IEC 60904-9. Some high-end BC cell sorters have spectral adjustment capabilities to adapt to the spectral response characteristics of specific BC structures.

　　Intelligent visual positioning and detection system:

　　High resolution back electrode imaging: Using a high-resolution industrial camera to accurately identify the complex electrode patterns on the back of the battery, guiding the probe card to precisely align each test point.

　　Positive high-sensitivity appearance detection: using high dynamic range imaging, multi angle illumination, and even polarized light technology to enhance the detection ability of subtle defects (scratches, pits, stains, color differences, and broken edges) on the front of BC batteries. Integrate AI algorithms for automatic classification and judgment of defects. The BC battery cell sorter is the key "eye" for quality control.

　　Efficient and flexible transmission and positioning platform:

　　Precision robotic arm/conveyor belt: Achieve fast, smooth, and non-destructive transmission of battery cells.

　　Micron level high-precision positioning platform: ensures precise positioning of battery cells at each testing station (such as electrical testing, appearance, EL), with repeat positioning accuracy typically within ± 10 microns, meeting the high-precision testing requirements of BC batteries.

　　Electroluminescence (EL) integrated detection (optional or standard):

　　Integrate online or near line EL testing units, apply current to BC battery cells to make them glow, capture images through high-sensitivity cameras, and perform non-destructive testing of internal defects (such as hidden cracks, broken grids, poor sintering, PN junction defects, and poor contact). EL images are the "gold standard" for evaluating the internal quality of BC batteries, and the BC cell sorter combines EL data to achieve more comprehensive performance quality correlation sorting.

　　Intelligent data management and grading system:

　　Real time collection and processing of massive data on electrical performance parameters (efficiency η, open circuit voltage Voc, short-circuit current Isc, fill factor FF, series resistance Rs, parallel resistance Rsh), appearance grade, EL defect grade, etc.

　　According to the preset grading rules (such as efficiency, voltage, appearance level, EL level combination), the battery cells are automatically sorted into different bins, and the sorting mechanism (such as air nozzle, robotic arm) is driven to place the battery cells into the corresponding material box. The BC battery cell sorter achieves closed-loop decision-making of data.

　　The core value of the sorter in BC battery manufacturing

　　Deploying high-performance BC cell sorter brings irreplaceable value to BC battery manufacturing:

　　Realize high-precision efficiency grading: Accurately measure and select battery cells with different efficiency grades, laying the foundation for optimal power matching and cost control in subsequent component packaging. Avoid the "barrel effect" and maximize the output power of components.

　　Ensure electrode contact quality: Through electrical parameters (such as Rs, FF) and EL detection, effectively identify and eliminate battery cells with poor backside metallization contact (such as virtual soldering, high contact resistance), ensuring long-term reliability of the components.

　　Strict appearance quality control: Select battery cells that meet high-end aesthetic requirements (uniform color, no defects), and meet market demands for high aesthetics such as household use and BIPV.

　　Accurate interception of internal defects: Combined with EL detection, efficiently identify internal defects such as hidden cracks and sintering problems, prevent them from flowing into the component process and causing potential failure or power loss, reduce component production risks and after-sales costs.

　　Improve manufacturing yield and pass through rate: Fast and accurate online sorting can promptly remove defective products, avoiding waste in subsequent high-value processes such as string welding, and improving overall manufacturing efficiency and yield.

　　Providing data support for process optimization: Massive sorting data (efficiency distribution, parameter fluctuations, defect type statistics) is a key basis for feedback on the status of the preceding processes (such as diffusion, coating, metallization) in battery production lines, driving continuous process improvement and stability enhancement. The BC battery cell sorter is a "data engine" for process optimization.

　　Technological Evolution and Future Directions

　　With the development of BC technology towards higher efficiency, larger size, and lower cost, higher requirements have been put forward for BC cell sorting instruments:

　　Higher accuracy and speed: Continuously improve current measurement accuracy (especially for ultra efficient batteries>26%), while maintaining or increasing testing and sorting cycles (such as<1 second/piece) to meet GW level production requirements.

　　More intelligent defect recognition: Deepen the application of AI in visual inspection and EL image analysis, improve the recognition accuracy and classification ability of complex and subtle defects, and reduce misjudgments and omissions.

　　Non destructive contact and lower shadow: Developing new ultra-low shadow (<0.2%), long-life, and non-destructive contact technologies (such as advanced material probes and exploration of non-contact sensing technology).

　　Multi parameter deep fusion grading: Combining multi-dimensional data such as efficiency, electrical parameters, EL defect severity, and appearance level to make more refined and intelligent grading decisions, achieving the maximum utilization of battery cell value.

　　Adapting to new BC structures: providing customized testing solutions and probe card designs for different BC technology routes such as IBC, TBC, HBC (HJT back contact), etc. The BC battery cell sorter needs to maintain technological foresight.

　　Integration and online monitoring: data exchange with upstream battery manufacturing equipment (such as PECVD, PVD, metallization) and downstream component production lines (such as string welding machines) to achieve full process quality traceability and real-time process closed-loop control.

　　Conclusion: The Precision Foundation of BC Technology Implementation

　　The BC battery cell sorter is the key to unlocking the high efficiency and commercial value of BC batteries. It ensures that every BC battery carrying cutting-edge technology can be fully utilized and achieve maximum efficiency through precise measurement, intelligent recognition, and efficient classification within a square inch. From improving component power to ensuring long-term reliability, from meeting high-end aesthetics to optimizing manufacturing costs, the role of BC cell sorter runs through the entire process. With the continuous expansion of the BC technology route in the high-end photovoltaic market, more advanced, intelligent, and efficient BC cell sorting instruments will continue to serve as indispensable "precision sieves", providing solid technical support for the photovoltaic industry to move towards a more efficient and high-quality future.

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