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    "title": "Why Bussing (Overlap Soldering) Causes Cell Cracks During Lamination in PV Modules -  - Ooitech, the world's leading solar panel production line solutions provider, supply chain expert, solar panel making machine facotry",
    "description": "A hands-on breakdown of the three most common bussing-related causes of center hole cell cracks during PV module lamination, from ribbon-cell spacing to solder ring defects.",
    "keywords": "solar panel bussing cracks, PV module center hole cracks, TOPCon cell cracking, lamination cell crack, overlap soldering defect, solar module production defect",
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        {
            "level": 2,
            "text": "Why Bussing (Overlap Soldering) Causes Cell Cracks During Lamination in PV Modules"
        },
        {
            "level": 3,
            "text": "Why Bussing (Overlap Soldering) Causes Cell Cracks During Lamination in PV Modules"
        },
        {
            "level": 5,
            "text": "Product Introduction"
        },
        {
            "level": 5,
            "text": "Technical Parameters"
        },
        {
            "level": 6,
            "text": "Reserved gap between ribbon and cell edge is too small"
        },
        {
            "level": 5,
            "text": "Technical Advantages"
        },
        {
            "level": 6,
            "text": "Ribbon bends and deforms after forming"
        },
        {
            "level": 6,
            "text": "Solder ring defect during bussing (a rarer batch cause)"
        },
        {
            "level": 5,
            "text": "Product Application"
        },
        {
            "level": 5,
            "text": "Ooitech's View"
        },
        {
            "level": 5,
            "text": "Tags :"
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        {
            "level": 5,
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            "text": "Category"
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            "text": "Recent Post"
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        {
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        },
        {
            "level": 5,
            "text": "Popular Tags"
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            "level": 3,
            "text": "Request A Quote"
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            "level": 2,
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        {
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            "text": "Cost-Effective Advantages"
        },
        {
            "level": 3,
            "text": "Our Experience Team"
        },
        {
            "level": 3,
            "text": "15+ Years Industry Experience"
        },
        {
            "level": 2,
            "text": "What Our Client Say's about us"
        },
        {
            "level": 3,
            "text": "Jizzakh Polytechnic Institute"
        },
        {
            "level": 3,
            "text": "KTECH"
        },
        {
            "level": 3,
            "text": "Amjad"
        },
        {
            "level": 3,
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        }
    ],
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    "markdown": "# Why Bussing (Overlap Soldering) Causes Cell Cracks During Lamination in PV Modules -  - Ooitech, the world's leading solar panel production line solutions provider, supply chain expert, solar panel making machine facotry\n\n> A hands-on breakdown of the three most common bussing-related causes of center hole cell cracks during PV module lamination, from ribbon-cell spacing to solder ring defects.\n\n![Why Bussing (Overlap Soldering) Causes Cell Cracks During Lamination in PV Modules](https://cdn.ooitech.com/static/upload/image/20260720/ebbce32ad421e96747076e9f11fe59f4.webp)\n\n- ** 2026-07-20\n- ** 0 Views\n- ** [Blog](/Blog.html)\n\n### Why Bussing (Overlap Soldering) Causes Cell Cracks During Lamination in PV Modules\n\n##### Product Introduction\n\nCenter hole cracks are the most frequent cosmetic defect you run into on a PV module line. The causes are messy and there are a lot of them. This post narrows things down and looks only at the center hole cracks that come from problems in the bussing (overlap soldering) step. Three typical root causes, walked through one at a time.\n\n##### Technical Parameters\n\n###### Reserved gap between ribbon and cell edge is too small\n\nThe cell edge sits too close to the bus bar.\n\nTOPCon cell strings use a front-side ribbon positive structure, and the ribbon is soldered to the back of the bus bar. During bussing the machine does bring the cell and bus bar to the same plane, but the two materials differ a lot in thickness:\n\n| Item | Thickness |\n| --- | --- |\n| Standard TOPCon wafer | 0.13mm |\n| Middle bus bar | 0.35mm~0.4mm |\n\nOnce you get into lamination, the contact area where the ribbon meets the cell edge sees a two-way force.\n\nWhen the gap between cell and bus bar is too small, the angle between the ribbon and the wafer edge shrinks. Pull force F1 drops, and vertical pressure F2 goes up at the same time.\n\nWafers are brittle. Under that higher pressure the edge cracks easily, and you end up with a center hole crack.\n\n##### Technical Advantages\n\n###### Ribbon bends and deforms after forming\n\nIf the plane difference between cell and bus bar is too large during bussing, the ribbon keeps a height difference after it's soldered.\n\nBussing has already fixed the total ribbon length. The extra length has nowhere to go, so the ribbon bends to absorb it. That bent ribbon then keeps pressing on the cell edge, and you get batch center hole cracks.\n\n###### Solder ring defect during bussing (a rarer batch cause)\n\nHere the cell and bus bar have a slight plane difference during bussing, and the harpoon area has no bus bar support, so the ribbon separates from the wafer. When the solder heat melts the ribbon coating, a raised ring of solder forms around it. During lamination pressure this hard solder ring pushes straight into the wafer and cracks it, giving another center hole crack.\n\n##### Product Application\n\nThese three failure modes show up across most crystalline module lines, and they matter most on thin, high-efficiency cells where the mechanical margin is already tight. Watching ribbon-to-cell spacing, plane alignment during bussing, and solder profile control gives you the biggest lever on center hole crack yield.\n\n##### Ooitech's View\n\nThin TOPCon wafers at 0.13mm leave almost no room for error, so the F1/F2 force balance we talk about here is really an alignment problem you solve upstream at the stringer and bussing stations, not something you can fix later in lamination. On the module lines we build, keeping the cell and bus bar coplanar and holding a steady solder profile is where most center-crack yield actually comes from. If you want to see how these steps run in a real factory, Ooitech's YouTube channel [www.youtube.com/ooitech](http://www.youtube.com/ooitech) has plenty of line footage worth a look.\n\n---\n\n##### Tags :\n\n\n![](/template/ooitech/assets/img/shape/06.png)\n\n![](https://cdn.ooitech.com/runtime/image/w800_h700_fitblur_v2_w800_h700_fitblur_v2_1757399770541443.webp)\n\n### Request A Quote\n\nAll uploads are secure and confidential.\n\n## We deliver expertise you can trust our service\n\nDirect-from-Factory Equipment.\n\n![](/template/ooitech/assets/img/icon/money-2.svg)\n\n### Cost-Effective Advantages\n\nWe deliver exceptional value, maximizing results while optimizing budgets for clients.\n\n![](/template/ooitech/assets/img/icon/staff.svg)\n\n### Our Experience Team\n\nOur skilled professionals specialize in innovative solutions and tailored strategies.\n\n![](/template/ooitech/assets/img/icon/certified.svg)\n\n### 15+ Years Industry Experience\n\nDeep expertise ensures reliable, trend-aware, and proven outcomes for success.\n\n![](https://cdn.ooitech.com/static/upload/image/20250910/1757477357667605.webp )\n\n![](https://cdn.ooitech.com/static/upload/image/20250910/1757477724911512.webp)\n\n![](/template/ooitech/assets/img/shape/06.png)\n\n## What Our Client Say's about us\n\nClient testimonials praise our deep understanding of their challenges, which leads to innovative solutions and strong ROI. Long-term collaborations—some over a decade—demonstrate their trust and satisfaction. Their success stories drive us to continually exceed expectations. [Know More **](#quote-form)\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nA man with a big soul. Thank you very much for your visit Mr Wu. Thank you very much for the services provided in installing equipment and training my students. 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