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    "title": "BC Solar Cells Explained: Structure, Differences, Manufacturing Process and String Soldering Principle -  - Ooitech, the world's leading solar panel production line solutions provider, supply chain expert, solar panel making machine facotry",
    "description": "A practical English blog explaining BC back contact solar cells, including IBC structure, differences from TOPCon PERC and HJT cells, manufacturing process, busbar layout, and the basic principle of BC cell string soldering.",
    "keywords": "BC solar cell, back contact solar cell, IBC cell, TBC cell, HBC cell, HPBC, ABC solar cell, solar cell string soldering, back contact module, BC cell welding, solar module production",
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            "text": "BC Solar Cells Explained: Structure, Differences, Manufacturing Process and String Soldering Principle"
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            "level": 3,
            "text": "BC Solar Cells Explained: Structure, Differences, Manufacturing Process and String Soldering Principle"
        },
        {
            "level": 5,
            "text": "Product Introduction"
        },
        {
            "level": 6,
            "text": "What Makes BC Cells Different"
        },
        {
            "level": 5,
            "text": "Technical Parameters"
        },
        {
            "level": 6,
            "text": "Typical BC Cell Structure"
        },
        {
            "level": 6,
            "text": "IBC Cell Manufacturing Process"
        },
        {
            "level": 5,
            "text": "Technical Advantages"
        },
        {
            "level": 6,
            "text": "No Front-Side Grid Shading"
        },
        {
            "level": 6,
            "text": "Higher Efficiency Potential"
        },
        {
            "level": 6,
            "text": "Flexible Technology Integration"
        },
        {
            "level": 6,
            "text": "Special Rear-Side Grid Design"
        },
        {
            "level": 5,
            "text": "Product Application"
        },
        {
            "level": 6,
            "text": "BC Cell String Soldering Principle"
        },
        {
            "level": 5,
            "text": "Contact and Purchase"
        },
        {
            "level": 6,
            "text": "Practical Notes for BC Module Manufacturing"
        },
        {
            "level": 5,
            "text": "Ooitech's View"
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            "level": 5,
            "text": "Tags :"
        },
        {
            "level": 5,
            "text": "Category"
        },
        {
            "level": 5,
            "text": "Recent Post"
        },
        {
            "level": 6,
            "text": "Solar Cell Stringer Machine Market and Technology Report 2026: TOPCon, BC, HJT and 0BB Trends"
        },
        {
            "level": 6,
            "text": "BC Solar Cells Explained: Structure, Differences, Manufacturing Process and String Soldering Principle"
        },
        {
            "level": 6,
            "text": "Why EL Testing Can Reveal Hidden Micro-Cracks in Solar Cells"
        },
        {
            "level": 6,
            "text": "EPE Encapsulant Lamination Delamination: Line-Shaped Bubbles Along Solar Cell Ribbons"
        },
        {
            "level": 6,
            "text": "Solar Panel Production Process: Lamination"
        },
        {
            "level": 5,
            "text": "Popular Tags"
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        {
            "level": 3,
            "text": "Request A Quote"
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            "level": 2,
            "text": "We deliver expertise you can trust our service"
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            "level": 3,
            "text": "Cost-Effective Advantages"
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            "text": "Our Experience Team"
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            "level": 2,
            "text": "What Our Client Say's about us"
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            "text": "Jizzakh Polytechnic Institute"
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        {
            "level": 3,
            "text": "Amjad"
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            "level": 3,
            "text": "Mark"
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            "level": 3,
            "text": "KTECH"
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        {
            "level": 2,
            "text": "Our Latest Products"
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        {
            "level": 3,
            "text": "HDX200-P Half Cell Auto Bussing Machine | Automatic Busbar Welding Machine for Solar Panel Production"
        },
        {
            "level": 3,
            "text": "CHT9980A/CHT9981A PV Safety Comprehensive Tester | Solar Panel Hipot Insulation Ground Continuity Tester"
        },
        {
            "level": 3,
            "text": "SC-20D Dual-Laser Solar Cell Cutting Machine for Shingled Solar Cell Production"
        },
        {
            "level": 3,
            "text": "Solar Panel Tester Sun Simulator OTMT-A | AAA Class Solar Module IV Tester | Ooitech"
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            "level": 3,
            "text": "STW-60A Automatic Shingled String Cell Terminal Head Welding Machine | Solar Module Busbar Welding Equipment"
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    "markdown": "# BC Solar Cells Explained: Structure, Differences, Manufacturing Process and String Soldering Principle -  - Ooitech, the world's leading solar panel production line solutions provider, supply chain expert, solar panel making machine facotry\n\n> A practical English blog explaining BC back contact solar cells, including IBC structure, differences from TOPCon PERC and HJT cells, manufacturing process, busbar layout, and the basic principle of BC cell string soldering.\n\n![BC Solar Cells Explained: Structure, Differences, Manufacturing Process and String Soldering Principle](https://cdn.ooitech.com/static/upload/image/20260708/500532e4b866927f836b0a06cfc6a8fe.webp)\n\n- ** 2026-07-08\n- ** 0 Views\n- ** [Blog](/Blog.html)\n\n### BC Solar Cells Explained: Structure, Differences, Manufacturing Process and String Soldering Principle\n\n##### Product Introduction\n\nBC solar cell, short for **Back Contact solar cell**, is a high-efficiency crystalline silicon cell technology where the emitter, back surface field and metal electrodes are all placed on the rear side of the cell. Its basic form is usually known as IBC, or **Interdigitated Back Contact** cell.\n\nCompared with conventional crystalline silicon cells, the most visible feature of BC cells is that there are no metal grid lines on the front surface. Since the front side is free from busbar and finger shading, more sunlight can enter the cell surface, optical loss is reduced, and the effective power generation area is increased. This is why BC cells are often used for high-efficiency and high-aesthetic solar modules.\n\n###### What Makes BC Cells Different\n\nThe key difference between BC cells and PERC, TOPCon or HJT cells is not simply the wafer type or a single passivation layer. The core idea of BC technology is structural: **the PN junction and metal electrodes are moved to the rear side of the cell**.\n\nFor example, TOPCon is often discussed in relation to N-type silicon substrates, front-side passivation, and rear-side tunnel oxide passivated contact structures. PERC is usually based on rear passivation improvement. HJT uses amorphous silicon passivation and heterojunction contact. BC, however, focuses on removing front-side electrode shading by moving the current collection structure to the back.\n\nBecause of this, BC can also be combined with other cell technologies. Pure BC technology is generally represented by IBC. **TOPCon plus BC can form TBC technology; HJT plus BC can form HBC technology. HPBC is commonly known as a P-type IBC-related route, while ABC refers to All Back Contact technology, often discussed together with silver-reduction or silver-free design concepts.**\n\n##### Technical Parameters\n\n###### Typical BC Cell Structure\n\nTaking IBC as an example, the most important structural change is that both the PN junction and the metal electrodes are located on the rear side of the cell. The front surface is mainly used for light absorption and passivation, while the rear surface completes carrier separation and current collection through interdigitated positive and negative regions.\n\n| Item | Description |\n| --- | --- |\n| Cell type | Back Contact solar cell |\n| Basic technology route | IBC, Interdigitated Back Contact |\n| Front side feature | No front-side metal grid line shading |\n| Rear side feature | Positive and negative electrodes arranged on the back side |\n| Core structural design | PN junction and metal electrodes moved to the rear side |\n| Main benefit | Reduced optical shading loss and improved effective light absorption area |\n| Compatible routes | IBC, TBC, HBC, HPBC, ABC and other BC-based structures |\n| Module process impact | Requires different string soldering logic compared with PERC, TOPCon and HJT cells |\n\n###### IBC Cell Manufacturing Process\n\nA typical IBC cell process can be summarized as follows:\n\n1. Chemical polishing and damage removal\n2. BBr3 tube diffusion\n3. Dry oxygen mask growth\n4. Screen printing for local BSF opening\n5. POCl3 tube diffusion\n6. Texturing\n7. Double-side passivation\n8. Screen printing for local contact opening\n9. Screen printing metallization\n\nThe core challenge of BC technology is how to prepare high-quality p-type and n-type regions on the back of the cell in an interdigitated pattern. In a typical process, a boron-containing interdigitated diffusion mask can be printed on the rear side. After diffusion, boron enters the N-type substrate and forms the p+ region. The area without the printed mask can then form the n+ region through phosphorus diffusion.\n\nOn the front side, pyramid texturing is used to enhance light trapping, while a front surface field, often called FSF, is formed to improve electrical performance. This combination of optical management and rear-side carrier collection is one reason why BC technology is attractive for premium modules.\n\n##### Technical Advantages\n\n###### No Front-Side Grid Shading\n\nThe most direct advantage of BC cells is that the front surface has no metal grid line. This reduces shading loss and increases light utilization. For module appearance, the all-black or near-uniform front surface can also deliver a cleaner visual effect, which is especially attractive in distributed commercial, industrial and building-related PV applications.\n\n###### Higher Efficiency Potential\n\nBecause the front surface can receive more incident light, BC cells have a strong theoretical and practical efficiency advantage. When combined with advanced passivation technologies such as TOPCon or HJT, BC structures can further improve conversion efficiency.\n\n###### Flexible Technology Integration\n\nBC is not limited to one single cell route. It can work as a platform structure and combine with other high-efficiency technologies. This is why the industry discusses routes such as TBC, HBC, HPBC and ABC. The common direction is the same: reduce optical loss, improve carrier collection, and raise module power output.\n\n###### Special Rear-Side Grid Design\n\nSince both positive and negative electrodes are located on the back side, the grid layout of BC cells is quite different from conventional cells. The following example uses red lines for positive busbars and blue lines for negative busbars, taking an 18BB rear-side layout as an example.\n\nWhen the fine fingers are also shown, the positive and negative fingers are arranged in an interdigitated pattern. The PN junction regions are also distributed in a similar interdigitated way. The main busbars collect current by crossing and connecting with the corresponding finger structure.\n\nFrom the real BC cell image, we can see not only the rear-side grid lines, but also PAD points on both sides of the half-cell. These PAD points are important for electrical connection and soldering design, especially in high-density interconnection structures.\n\n##### Product Application\n\n###### BC Cell String Soldering Principle\n\nBC cell soldering is different from conventional PERC or TOPCon cell soldering. For common double-side-grid cells, the ribbon usually connects from the rear side of one cell to the front side of the next cell. In BC cells, both positive and negative electrodes are on the rear side, so the soldering ribbon must follow a different connection path.\n\nAs shown in the diagram, BC string soldering realizes cell series connection by using soldering ribbons in a cyclic and staggered pattern between two adjacent cells. This is different from the welding method used for TOPCon cells, where the ribbon travels from the back of one cell to the front of the next cell.\n\nA full cell can be divided into two half-cells, A and B. The electrodes of the A half-cell and B half-cell are arranged opposite to each other. During BC cell string soldering, the ribbon from the starting cell is pulled to the negative electrode of the A half-cell and then cut. The following connection logic is then repeated:\n\n- From the positive electrode of A half-cell on cell 1 to the negative electrode of B half-cell on the same cell\n- From the positive electrode of B half-cell on cell 1 to the negative electrode of A half-cell on cell 2\n- Repeat the above cycle to complete the cell string connection\n\nIn the highlighted area, the ribbon is actually one continuous ribbon. Different colors are used only to make the positive and negative electrode relationship easier to understand. The diagram clearly shows the cyclic staggered welding pattern on the BC cell.\n\nThe completed cell string shows how the welding ribbons are arranged across multiple BC cells. This type of stringing requires accurate ribbon placement, stable tension control, precise positioning, and a good understanding of the rear-side electrode pattern.\n\nThe current flow diagram further explains the series connection principle. Since the current path is formed on the rear side through staggered ribbon routing, BC stringing equipment and process control are more demanding than standard ribbon soldering for traditional cells.\n\n##### Contact and Purchase\n\n###### Practical Notes for BC Module Manufacturing\n\nFor manufacturers planning to produce BC modules, the cell stringing section is one of the most important process points. The rear-side electrode design means that conventional stringing logic cannot simply be copied. Equipment must support accurate back-contact alignment, controlled ribbon feeding, stable soldering temperature, and reliable inspection after welding.\n\nIn production, engineers should pay close attention to ribbon offset, solder joint quality, cell cracking risk, PAD point matching and current path consistency. Any small deviation in rear-side soldering may cause resistance increase, power loss, or reliability issues after lamination and long-term outdoor operation.\n\n##### Ooitech's View\n\nAs an equipment supplier, we see it this way: BC technology is not only a cell-efficiency upgrade, but also a module manufacturing challenge, especially in string soldering accuracy and rear-side interconnection control. For a solar panel production line, the key is to match the stringer design with the real BC cell electrode pattern rather than treating it like a modified TOPCon or PERC process. In our view, factories evaluating BC modules should verify soldering stability, ribbon routing and EL performance at pilot scale before moving to mass production.\n\n---\n\n##### Tags :\n\n\n![](/template/ooitech/assets/img/shape/06.png)\n\n![](https://cdn.ooitech.com/static/upload/image/20250909/1757399770541443.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. 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The kindest person and professional in his field\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026041716444445.webp)\n\n### Jizzakh Polytechnic Institute\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nThanks to Ooitech for providing the fully automated production equipment—your installation and after-sales service have been excellent.\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026041720921238.webp)\n\n### Amjad\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nThank you again so much again for the very big big help for improving and fixing the factory and also teaching the workers how to use the machines\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1757479675272137.webp)\n\n### Mark\n\nBIPV Philippines\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nThanks to Ooitech for providing highly suitable BC solar cell experimental equipment.\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1776426122864564.webp)\n\n### KTECH\n\n## Our Latest Products\n\n![HDX200-P Half Cell Auto Bussing Machine | Automatic Busbar Welding Machine for Solar Panel Production](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1774341533138807.webp)\n\n- [** Rachael](/hdx200-p-half-cell-auto-bussing-machine-automatic-busbar-welding-machine-for-solar-panel-production.html)\n- [** 84352](/hdx200-p-half-cell-auto-bussing-machine-automatic-busbar-welding-machine-for-solar-panel-production.html)\n\n### HDX200-P Half Cell Auto Bussing Machine | Automatic Busbar Welding Machine for Solar Panel Production\n\nHDX200-P Half Cell Auto Bussing Machine features electromagnetic induction welding with 18 welding heads, cycle time under 18 seconds, and over 99% yield rate. Compatible with 156-230mm solar cells and 5-30 busbars, supporting PERC, TOPCon, and HJT half-c\n\n![CHT9980A/CHT9981A PV Safety Comprehensive Tester | Solar Panel Hipot Insulation Ground Continuity Tester](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026032763823477.jpg)\n\n- [** Rachael](/cht9980a-cht9981a-pv-safety-comprehensive-tester-solar-panel-hipot-insulation-ground-continuity-tester.html)\n- [** 83451](/cht9980a-cht9981a-pv-safety-comprehensive-tester-solar-panel-hipot-insulation-ground-continuity-tester.html)\n\n### CHT9980A/CHT9981A PV Safety Comprehensive Tester | Solar Panel Hipot Insulation Ground Continuity Tester\n\nCHT9980A/CHT9981A PV Safety Comprehensive Tester is a high-performance 3-in-1 instrument integrating DC withstand voltage, insulation resistance, and ground continuity testing for solar panel production lines. Compliant with IEC61215 and IEC61730 standard\n\n![SC-20D Dual-Laser Solar Cell Cutting Machine for Shingled Solar Cell Production](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1773917787610971.webp)\n\n- [** ooitech](/SC-20D-Full-Automatic-Solar-Cell-Laser-Cutting-Machine-High-Precision-Wafer-Scribing-Equipment.html)\n- [** 50879](/SC-20D-Full-Automatic-Solar-Cell-Laser-Cutting-Machine-High-Precision-Wafer-Scribing-Equipment.html)\n\n### SC-20D Dual-Laser Solar Cell Cutting Machine for Shingled Solar Cell Production\n\nSC-20D is the advanced version of SC-20A, specially designed for shingled solar cell production, featuring dual laser heads and two lasers working simultaneously for higher-throughput cutting.\n\n![Solar Panel Tester Sun Simulator OTMT-A | AAA Class Solar Module IV Tester | Ooitech](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1774513832212306.jpg)\n\n- [** ooitech](/solar-panel-tester-sun-simulator-otmt-a-aaa-class-solar-module-iv-tester-ooitech.html)\n- [** 302](/solar-panel-tester-sun-simulator-otmt-a-aaa-class-solar-module-iv-tester-ooitech.html)\n\n### Solar Panel Tester Sun Simulator OTMT-A | AAA Class Solar Module IV Tester | Ooitech\n\nOoitech OTMT-A Solar Panel Tester Sun Simulator is an AAA class solar module IV testing system featuring xenon lamp technology, IEC 60904-9 compliance, ±2% light non-uniformity, and 300,000 flash lamp life. Ideal for mono-Si and poly-Si solar panel produc\n\n![STW-60A Automatic Shingled String Cell Terminal Head Welding Machine | Solar Module Busbar Welding Equipment](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1774264892557837.webp)\n\n- [** ooitech](/stw-60a-automatic-shingled-string-cell-terminal-head-welding-machine-solar-module-busbar-welding-equipment.html)\n- [** 77832](/stw-60a-automatic-shingled-string-cell-terminal-head-welding-machine-solar-module-busbar-welding-equipment.html)\n\n### STW-60A Automatic Shingled String Cell Terminal Head Welding Machine | Solar Module Busbar Welding Equipment\n\nSTW-60A automatic shingled string cell terminal head welding machine by Ooitech uses infrared heating technology to weld busbars on both positive and negative terminals of solar cell strings. Supports 158.75mm, 166mm, and 210mm cells with a cycle time of\n\n![Portable HD EL Tester for Solar Module Inspection Portable EL tester](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026051214015103.webp)\n\n- [** ooitech](/portable-hd-el-tester-for-solar-module-inspection.html)\n- [** 154](/portable-hd-el-tester-for-solar-module-inspection.html)\n\n### Portable HD EL Tester for Solar Module Inspection Portable EL tester\n\nPortable high definition EL tester with 24MP auto focus infrared camera for solar module electroluminescence testing, supporting USB and WiFi connection for laboratory and field inspection.\n",
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