Manufacturing method of main-grid-free photovoltaic module

Abstract

The invention discloses a main-grid-free photovoltaic module manufacturing method, and relates to the field of photovoltaic module manufacturing, and the method comprises the steps: preparing a main-grid-free battery piece, a welding strip and an adhesive film, enabling the battery piece to only have fine grid lines, and setting PAD points at the edges of the two sides; welding strips are fixed on the PAD points through welding; placing the adhesive film on the main-grid-free battery piece welded with the welding strip, and preheating to bond the welding strip; laying a battery string on the front plate, and connecting the battery string with a bus bar; the back plate is placed on the front plate, and lamination is carried out after the bus bar is led out; and installing a frame and a junction box, and pasting a label to obtain the main-grid-free photovoltaic module. According to the method, a conventional adhesive film is used for replacing a skin film, a main grid is omitted, material cost is reduced, and reliability of the assembly is improved through a conventional welding strip. By optimizing the contact area of the welding strip and the fine grid line, the capability of resisting cyclic load and thermal cycling of the assembly is improved. A skin film and a low-temperature welding strip do not need to be introduced in the whole manufacturing process, so that the manufacturing cost is reduced, and the reliability of the assembly is improved.

Description

Technical Field

[0001] The invention relates to the field of photovoltaic module manufacturing, and in particular to a method for manufacturing a main grid-free photovoltaic module. Background Art

[0002] Busbar-free photovoltaic modules, also known as 0BB (Zero Busbar) modules, are photovoltaic modules produced using busbar-free photovoltaic cells. The welding strips are welded to the thin grid lines of the busbar-free cells. The current collected by the thin grid lines is directly collected on the welding strips, and the current is led out through the welding strips. Busbar-free photovoltaic modules do not need to print the busbars on the cells, which reduces the silver paste consumption of the cells and the production cost of the modules. After the busbars are eliminated, the shading area of ​​the grid lines can be reduced, which increases the power generation of the modules.

[0003] At present, the existing technology usually adopts the laminating process to produce busbar-free photovoltaic modules. Two new materials, skin film and low-temperature welding tape, need to be introduced during production. The skin film made of modified adhesive film has two functions. On the one hand, it fixes the photovoltaic welding tape on the battery cell during the busbar-free battery string process. On the other hand, it prevents the melted adhesive film from flowing between the welding tape and the battery during the lamination process, avoiding the increase of internal resistance between the photovoltaic cell and the welding tape and the problem of EL test welding tape shadow. Since the skin film is easy to melt at high temperature, conventional welding technology cannot be used to weld photovoltaic modules. It is necessary to melt the solder on the welding tape during the lamination process, and then realize metallization interconnection with the fine grid line of the battery. However, the lamination process temperature of photovoltaic modules is generally around 150°C, so it is necessary to use more expensive low-temperature welding tape. The low melting point of the welding tape will also greatly reduce the performance of the module in resisting hot spots, thermal cycles, and damp heat.

[0004] In view of the above problems existing in the prior art, in order to reduce the manufacturing cost of photovoltaic modules and improve the reliability of the busbar-free modules, it is necessary to propose a busbar-free photovoltaic module manufacturing method. Summary of the invention

[0005] The purpose of the present invention is to provide a method for manufacturing a busbar-free photovoltaic module to solve the above-mentioned technical problems existing in the prior art.

[0006] To achieve the above object, the present invention provides the following solution: a method for manufacturing a busbar-free photovoltaic module, comprising the following steps:

[0007] S1. Prepare a busbar-free solar cell, a welding ribbon and an adhesive film, wherein the front and back sides of the busbar-free solar cell have only thin grid lines, the two side edges of the busbar-free solar cell are respectively arranged with a first PAD point and a second PAD point, and the upper and lower surfaces of each busbar-free solar cell are respectively provided with a separate adhesive film;

[0008] S2, welding the first and second ends of the welding strip to the first PAD point and the second PAD point respectively by welding;

[0009] S3, placing the adhesive film on the busbar-free solar cell with the welding ribbon, preheating the adhesive film to adhere the welding ribbon to the busbar-free solar cell;

[0010] S4, laying the battery string on the front plate, and connecting the battery string head to tail in sequence using a busbar;

[0011] S5, placing the back sheet on the front sheet on which the battery string is laid, and leading the busbars out from the holes of the back sheet for lamination;

[0012] S6. Install a frame on the laminated photovoltaic module, install a junction box, and affix a label to obtain a main grid-free photovoltaic module.

[0013] Optionally, the busbar-free cell is one of PERC, TOPCon, HJT, and XBC cells.

[0014] Optionally, the thin grid lines on the busbar-free solar cell are thickened at positions corresponding to the welding strips, and the width of the thin grid lines at the thickened positions is between 10 μm and 30 μm.

[0015] Optionally, a first welding spot and a second welding spot are respectively provided on the front and back sides of the busbar-free solar cell, and the width of the first welding spot and the second welding spot are between 0.2 mm and 0.6 mm, and the length is between 0.2 mm and 1 mm.

[0016] Optionally, the width of the adhesive film is greater than the width of the busbar-free battery cell, and the edges of the adhesive film between two adjacent battery strings are in contact with or overlap each other.

[0017] Optionally, the adhesive film is one of EVA, POE, and EPE adhesive films.

[0018] Optionally, the welding strip includes a copper core and solder located at the periphery of the copper core, and the diameter of the welding strip is between 0.1 mm and 0.3 mm.

[0019] Optionally, the solder component is one of Sn-Pb alloy, Sn-Pb-Ag alloy, Sn-Pb-Bi alloy, Sn-Pb-In alloy, and Sn-Bi-Ag alloy.

[0020] Optionally, the number of welding strips corresponding to the same busbar-free solar cell is between 10 and 30, and the welding strips on the upper and lower surfaces of the busbar-free solar cell are symmetrically distributed or staggered.

[0021] Optionally, the back panel is one of tempered glass, semi-tempered glass, TPT, KPK, TPE, KPE, TPO, KPO, TPX, KPX, PPE polymer materials produced by a composite process, CPC polymer materials produced by a coating process, TPC or KPC polymer materials produced by a superposition of coating and composite methods, and AOE or OOO polymer materials produced by a co-extrusion process.

[0022] The present invention discloses the following technical effects:

[0023] The present invention discloses a method for manufacturing a photovoltaic module without a main grid, aiming to reduce production costs and improve the reliability of the module. The method uses a conventional adhesive film instead of a skin film, eliminates the main grid, reduces material costs, and improves the reliability of the module through a conventional welding strip. In addition, by optimizing the contact area between the welding strip and the fine grid line, the ability of the module to resist cyclic loads and hot and cold cycles is improved. The entire manufacturing process does not require the introduction of a skin film and a low-temperature welding strip, thereby reducing manufacturing costs and improving the reliability of the module. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A flow chart of a method for manufacturing a busbar-free photovoltaic module provided by the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of a main grid-free photovoltaic module in the prior art;

[0027] Figure 3 It is a schematic diagram of the structure of a busbar-free photovoltaic module in the present invention;

[0028] Figure 4 A schematic diagram of the manufacturing process of a busbar-free photovoltaic module in the present invention;

[0029] Figure 5 It is a schematic diagram of a battery screen for a main grid-free battery cell in the present invention;

[0030] Figure 6 is a cross-sectional view of the welding strip in the present invention;

[0031] Figure 7 A structural diagram of a battery string in some embodiments of the present invention and a cross-sectional view at AA thereof;

[0032] Figure 8The structure diagram of the battery string and the cross-sectional view at BB in other embodiments of the present invention;

[0033] Fig. 9 It is a structural diagram of a laminate and a cross-sectional view at CC in some embodiments of the present invention;

[0034] Fig.10 The structure diagram of the laminated member in some other embodiments of the present invention and the cross-sectional view at DD thereof;

[0035] Fig.11 This is a material distribution diagram of the busbar-free photovoltaic module of the present invention after the lamination process.

[0036] In the figure: 1. backplane; 2. adhesive film; 2a. first side adhesive film; 2b. second side adhesive film; 3. main grid-free battery cell; 31. first PAD point; 32. second PAD point; 33. fine grid line; 34. thickened fine grid section; 4. front plate; 5. soldering ribbon; 51. copper core; 52. solder; 6. battery string; 7. laminate; 101. back glass; 102. back film; 103. back skin film; 104. battery cell; 105. front skin film; 106. front film; 107. front glass. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The introduction of the skin film during the manufacturing process of the busbar-free module increases the manufacturing cost, and the change in the fixing method of the welding strip 5 also affects the reliability of the module. Figure 2 As shown, Figure 2A structure of a conventional busbar-free photovoltaic module using a coating process in the prior art is shown, including front glass 107, front adhesive film 106, front skin film 105, battery cell 104, back skin film 103, back adhesive film 102, and back glass 101 stacked in sequence from bottom to top. In terms of cost, the busbar-free coating process of the conventional busbar-free photovoltaic module requires the introduction of skin film and low-temperature solder tape; the skin film, as a modified EVA material, is more expensive than conventional adhesive film; the low-temperature solder tape refers to a solder tape with a welding temperature not exceeding 175°C. The low-temperature solder tape is usually made by adding rare metal elements such as In, Bi, and Ag to the solder of the conventional solder tape to reduce the melting point of the solder to achieve low-temperature welding; the addition of rare metal elements to the low-temperature solder tape leads to increased costs. In terms of process, a layer of skin film is added to each side of the battery in the battery string produced by the coating process. The width of the skin film is smaller than the battery cell 104. After the conventional adhesive film is applied, the gap between adjacent battery strings becomes larger. Since there is less adhesive film between adjacent battery strings, bubbles are easily generated between the strings after the assembly is laminated. When the melting point of the solder ribbon is lower than the temperature of the lamination equipment, it becomes more difficult to change the string. After the solder ribbons are spliced ​​by overlapping the solder ribbons, the welding points will melt again during lamination and are easy to detach. If automatic string changing equipment is purchased, the production line cost will be greatly increased. In theory, 0BB batteries can generate electricity normally after fragments are generated. In fact, during the lamination process, the battery cell 104 generates fragments, and the solder on the front solder ribbon of the battery melts and penetrates through the cracks of the battery to the back of the battery. Contact with the back solder ribbon causes a short circuit, and the entire battery has no power after the short circuit. In terms of reliability, the melting point of the low-temperature solder ribbon used in the lamination process is lower than the lamination process temperature (about 150°C). The ability of components produced by the lamination process to resist hot spots and hot and cold cycles is reduced, resulting in an increase in component reliability risk.

[0039] To this end, the present invention discloses a method for manufacturing a busbar-free photovoltaic module, which uses a conventional adhesive film instead of a skin film during the module production process, thereby reducing the production cost of the busbar-free module and improving the reliability of the busbar-free module.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] First of all, it should be explained that the photovoltaic module referred to in the present invention refers to a crystalline silicon solar cell module, which is a power generation body formed by a series of solar cells connected in series or in parallel and packaged together in different arrangements.

[0042] Busbar-less photovoltaic cells are also called 0BB cells. Busbars are not set on the cell. In contrast, conventional photovoltaic cells in the prior art are provided with busbars and fine grids. The current generated by the photovoltaic cells is collected by the fine grids and collected on the busbars. The current is led out through the welding tape welded on the PAD point of the busbar (used to connect the metal contact point with the welding tape). Busbar-less photovoltaic modules are photovoltaic modules produced with busbar-less photovoltaic cells as the main raw materials.

[0043] Reference Figure 1 As shown, the present invention provides a method for manufacturing a busbar-free photovoltaic module, comprising the following steps:

[0044] S1. Prepare a busbar-free solar cell 3, a welding ribbon 5 and an adhesive film 2; the front and back sides of the busbar-free solar cell 3 only have thin grid lines 33, but no busbars, and a first PAD point 31 and a second PAD point 32 are arranged on the edges of both sides thereof, and a separate adhesive film 2 is arranged on the upper and lower surfaces of each busbar-free solar cell 3; the welding ribbon 5 includes a copper core 51 and a solder 52 coated on the surface of the copper core 51; the adhesive film 2 is cut to a size relative to the size of the busbar-free solar cell 3, and the adhesive film 2 uses a conventional EVA adhesive film 2, which has stable insulation and weather resistance.

[0045] S2, welding the welding ribbon 5; stretching the welding ribbon 5 and arranging it on the front and back of the busbar-free cell 3, and welding the two ends of the welding ribbon 5 to the first PAD point 31 and the second PAD point 32 of the busbar-free cell 3 respectively. This welding method can realize metallization interconnection and improve the current collection efficiency.

[0046] S3, preheating the adhesive film 2; placing the adhesive film 2 on the busbar-free battery cell 3 with the welding ribbon 5 welded thereon, and enhancing its viscosity by preheating the adhesive film 2, so that the welding ribbon 5 is adhered to the busbar-free battery cell 3 to achieve secondary fixation; specifically, placing a first adhesive film 2a and a second adhesive film 2b on the upper and lower sides of the busbar-free battery cell 3 with the welding ribbon 5, respectively, and making the two layers of adhesive film 2 adhere to the surface of the busbar-free battery cell 3 by preheating.

[0047] S4, laying the battery string 6; laying the battery string 6 directly on the front plate 4 (photovoltaic glass), and connecting the battery string 6 end to end in sequence using a busbar to form a battery string 6;

[0048] S5, laminating to obtain a laminate 7; placing the back sheet 1 (photovoltaic glass or conventional backside encapsulation material) on the front sheet 4 provided with the battery string 6, and laminating to obtain the laminate 7 after leading the busbars from the back sheet holes, to ensure the sealing and mechanical strength of the assembly;

[0049] S6. Install the frame and junction box; install the frame and junction box on the laminated photovoltaic module, and paste the label to finally form a complete busbar-free photovoltaic module.

[0050] In the above embodiment, a conventional adhesive film 2 is used instead of a skin film to reduce the production cost of the busbar-free assembly and improve the reliability of the busbar-free assembly.

[0051] In the above embodiment, two PAD points are reserved on the busbar-less cell 3 at the positions corresponding to the ends of the welding ribbon 5. The ends of the welding ribbon 5 are fixed on the busbar-less cell 3 before lamination, which can effectively prevent the welding ribbon 5 from moving during the lamination process.

[0052] In the above embodiment, conventional solder strips 5 are used to improve component reliability. By eliminating the problem of small contact area between the solder strips 5 and the fine grid lines 33 after the main grid and the middle PAD point, the component's ability to resist cyclic loads and hot and cold cycles is improved.

[0053] In the above embodiment, a busbar-free assembly process of welding before lamination is adopted, and the melting point of the welding ribbon 5 is greater than the lamination temperature, so as to improve the ability of the assembly to resist hot spots and reduce the assembly production cost.

[0054] In some embodiments, the busbarless battery cell 3 is one of PERC, TOPCon, HJT, and XBC batteries. The front and back sides of the busbarless battery cell 3 only have fine grid lines 33. The fine grid lines 33 are thickened at the position corresponding to the welding strip 5, and a fine grid thickening segment 34 is provided. The width of the fine grid line 33 of the fine grid thickening segment 34 is between 10μm and 30μm. The front and back sides of the busbarless battery cell 3 are respectively provided with a first welding point and a second welding point. The width of the welding point is between 0.2mm and 0.6mm, and the length of the welding point is between 0.2mm and 1mm.

[0055] The above-mentioned PERC cell, whose full name is Passivated Emitter and Rear Cell, is a high-efficiency solar cell technology. Its characteristic is that a passivation layer is added to the back of the cell. This passivation layer can reduce the recombination of electrons and improve the efficiency of the cell.

[0056] The above-mentioned TOPCon cell, whose full name is Tunnel Oxide Passivated Contact Cell, is an emerging photovoltaic technology with significant advantages of high efficiency and low cost.

[0057] The above-mentioned HJT cell, full name is Heterojunction with Intrinsic Thin-layer, is a new type of high-efficiency solar cell technology. It uses heterojunction technology to combine amorphous silicon thin film with crystalline silicon substrate to form a heterostructure, thereby improving the photoelectric conversion efficiency of solar cells.

[0058] The above-mentioned XBC cell, full name is cross-finger back contact cell, is a kind of N-type high-efficiency photovoltaic cell technology. The XBC cell adopts a front-side metal grid-free design, eliminating the shading loss of the grid electrode, thereby improving the photoelectric conversion efficiency.

[0059] In some embodiments, the adhesive film 2 is one of EVA, POE, and EPE adhesive films 2, the width of the adhesive film 2 is greater than the width of the battery, and the edges of the adhesive film 2 between two adjacent strings of batteries contact or overlap each other.

[0060] In some embodiments, the solder strip 5 includes an internal copper core 51 and an external solder 52, the solder 52 is composed of one of Sn-Pb alloy, Sn-Pb-Ag alloy, Sn-Pb-Bi alloy, Sn-Pb-In alloy, and Sn-Bi-Ag alloy, and the diameter of the solder strip 5 including the solder 52 is between 0.1 mm and 0.3 mm.

[0061] In some embodiments, the number of welding ribbons 5 corresponding to the same busbar-less solar cell 3 is between 10 and 30, and the upper welding ribbon 5 of the busbar-less solar cell 3 can be arranged corresponding to the lower welding ribbon 5 or asymmetrically with the lower welding ribbon 5 .

[0062] Compared with the prior art, the embodiments of the present invention at least disclose the following beneficial effects:

[0063] (1) The manufacturing method of busbar-free photovoltaic modules disclosed in the present invention of welding first and then coating is adopted. The welding ribbon 5 is welded on the surface of the battery cell 104 to realize metallized interconnection. There is no need to use a skin film to prevent the conventional adhesive film 2 from flowing between the welding ribbon 5 and the battery cell 104. Since the conventional adhesive film 2 itself has a certain viscosity, the pre-welded welding ribbon 5 can be directly adhered to the battery cell 104 with the conventional adhesive film 2 to achieve secondary fixation. Therefore, the skin film and low-temperature welding ribbon 5 in the traditional coating process can be eliminated, thereby reducing the manufacturing cost of the busbar-free module.

[0064] (2) Conventional busbar-free assemblies use skin membranes to fix the welding ribbon 5. Since there is no fixing point between the welding ribbon 5 and the battery itself, the melting of the skin membrane during lamination drives the welding ribbon 5 to move. Two PAD points are reserved on the battery at the positions corresponding to the ends of the welding ribbon 5. The ends of the battery are fixed on the battery before lamination, which can effectively prevent the welding ribbon 5 from moving during the lamination process.

[0065] (3) Low-temperature solder 52 is usually made of Sn-Pb-Bi alloy. Since the Bi element is not miscible with solder, a dense Bi metal layer will be formed after welding, causing the solder joint to become brittle. At the same time, since the contact area between the welding strip 5 and the fine grid line 33 is small after the main grid and PAD point are eliminated, the ability of the component to resist cyclic loads and hot and cold cycles is reduced. The method of welding first and then peritoneum disclosed in the present invention uses a conventional welding strip 5, which can improve the reliability of the component.

[0066] (4) The main grid-free component process using lamination welding needs to ensure that the melting point of the soldering tape 5 is lower than the lamination temperature. The lamination temperature of about 150°C is lower than the temperature when hot spots occur in the component. Therefore, components produced using low-temperature soldering tape 5 are at risk of hot spots. Conventional soldering tape 5 can not only improve the ability of the component to resist hot spots, but also reduce the production cost of the component.

[0067] The details not described in detail in the present invention are all conventional technical means well known to those skilled in the art.

[0068] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0069] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for manufacturing a busbar-free photovoltaic module, characterized in that: The following steps are involved: S1, preparing a busbar-free solar cell (3), a welding strip (5) and an adhesive film (2), wherein the front and back sides of the busbar-free solar cell (3) only have thin grid lines (33), the two side edges of the busbar-free solar cell (3) are respectively arranged with a first PAD point (31) and a second PAD point (32), and the upper and lower surfaces of each busbar-free solar cell (3) are respectively provided with a separate adhesive film (2); S2, welding the first and second ends of the welding strip (5) to the first PAD point (31) and the second PAD point (32) respectively by welding; S3, placing the adhesive film (2) on the busbar-free battery cell (3) welded with the welding strip (5), preheating the adhesive film (2) to adhere the welding strip (5) to the busbar-free battery cell (3); S4, laying the battery string (6) on the front plate (4), and connecting the battery string (6) end to end in sequence using a busbar; S5, placing the back plate (1) on the front plate (4) on which the battery string (6) is laid, and laminating after leading the busbars out from the holes in the back plate; S6. Install a frame on the laminated photovoltaic module, install a junction box, and affix a label to obtain a main grid-free photovoltaic module.

2. The method for manufacturing a busbar-free photovoltaic module according to claim 1, characterized in that: The busbar-free cell (3) is one of PERC, TOPCon, HJT, and XBC cells.

3. The method for manufacturing a busbar-free photovoltaic module according to claim 2, characterized in that: The thin grid lines (33) on the busbar-free battery cell (3) are thickened at positions corresponding to the welding strips (5), and the width of the thin grid lines (33) at the thickened positions is between 10 μm and 30 μm.

4. The method for manufacturing a busbar-free photovoltaic module according to claim 2, characterized in that: The front and back sides of the busbar-free solar cell (3) are respectively provided with a first welding point and a second welding point, wherein the width of the first welding point and the second welding point is between 0.2 mm and 0.6 mm, and the length is between 0.2 mm and 1 mm.

5. The method for manufacturing a busbar-free photovoltaic module according to claim 1, characterized in that: The width of the adhesive film (2) is greater than the width of the busbar-free battery sheet (3), and the edges of the adhesive film (2) between two adjacent battery strings (6) are in contact with or overlap each other.

6. The method for manufacturing a busbar-free photovoltaic module according to claim 1, characterized in that: The adhesive film (2) is one of EVA, POE, and EPE adhesive films (2).

7. The method for manufacturing a busbar-free photovoltaic module according to claim 1, characterized in that: The welding strip (5) comprises a copper core (51) and a solder (52) located on the outer periphery of the copper core (51); the diameter of the welding strip (5) is between 0.1 mm and 0.3 mm.

8. The method for manufacturing a busbar-free photovoltaic module according to claim 7, characterized in that: The solder (52) is composed of one of Sn-Pb alloy, Sn-Pb-Ag alloy, Sn-Pb-Bi alloy, Sn-Pb-In alloy and Sn-Bi-Ag alloy.

9. The method for manufacturing a busbar-free photovoltaic module according to claim 1, characterized in that: The number of welding strips (5) corresponding to the same busbar-free solar cell (3) is between 10 and 30, and the welding strips (5) on the upper and lower surfaces of the busbar-free solar cell (3) are symmetrically distributed or staggeredly distributed.

10. The method for manufacturing a busbar-free photovoltaic module according to claim 1, characterized in that: The back panel (1) is one of tempered glass, semi-tempered glass, TPT, KPK, TPE, KPE, TPO, KPO, TPX, KPX, PPE polymer materials produced by a composite process, CPC polymer materials produced by a coating process, TPC or KPC polymer materials produced by a coating and composite process, and AOE or OOO polymer materials produced by a co-extrusion process.

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