Zero-busbar photovoltaic cell string soldering method and zero-busbar photovoltaic cell string soldering apparatus

Abstract

A zero-busbar photovoltaic cell string soldering method and a zero-busbar photovoltaic cell string soldering apparatus. The method comprises: conveying zero-busbar photovoltaic cells and solder strips to a pre-soldering device, and performing heating so that each solder strip is pre-fixed on the surface of the corresponding zero-busbar photovoltaic cell, so as to obtain a cell string column; and conveying the cell string column to a position below a heating and pressurizing device, controlling the heating and pressurizing device to move to be in contact with a front film layer on the cell string column, and heating and pressurizing the front film layer to obtain a cell string. The cells and the solder strips are pre-fixed, then film laminating is performed, and the front film layer is heated and pressurized. During heating and pressurizing, it is not needed to place a pressing tool on a front surface, thereby avoiding uneven heating, avoiding the problems of bubbling of a film layer and a cold solder joint, ensuring the soldering quality, reducing the cold solder joint and grid breaking. When pre-soldering is finished, heating and pressurizing are carried out, thereby preventing the solder strip from deviating.

Description

A busbar-free photovoltaic cell string welding method and busbar-free photovoltaic cell string welding device

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on June 26, 2024, with application number 202410840624.8, and invention name “A method for string welding of photovoltaic cells without a main grid and a device for string welding of photovoltaic cells without a main grid”, and the Chinese patent application filed with the Patent Office of China on March 4, 2024, with application number 202410239688.2, and invention name “A photovoltaic cell string welding device and string welding method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of photovoltaic cell production, and in particular to a busbar-free photovoltaic cell string welding method and a busbar-free photovoltaic cell string welding device. Background Art

[0003] When busbarless photovoltaic cells are connected in series to form a string, the process sequence generally includes backside film application, backside soldering ribbon, busbarless photovoltaic cell placement, frontside soldering ribbon, frontside film application, and press tooling for positioning. The frontside film is heated using infrared light, which transfers heat from the outside in. Because a press tool is required to secure the frontside film and soldering ribbon, and infrared heating is a form of radiation, the press tooling can cause uneven heating temperatures across the busbarless photovoltaic cell surface, leading to film blistering and poor solder joints between the busbar and the soldering ribbon.

[0004] In addition, the above-mentioned front film layer and back film layer are laid for a single main grid-free photovoltaic cell. The film layer will also produce pre-cross-linking during the heating process, which will cause the front film layer to adhere to the press and the back film layer to adhere to the belt, increasing the risk of abnormalities such as welding ribbon deviation and cold welding.

[0005] Therefore, how to solve the above technical problems should be the focus of those skilled in the art. Summary of the Invention

[0006] The purpose of this application is to provide a busbar-free photovoltaic cell string welding method and busbar-free photovoltaic cell string welding equipment to avoid problems such as cold solder joints, broken grids, and blistering of the front film layer in the cell strings.

[0007] To solve the above technical problems, the present application provides a busbar-less photovoltaic cell string welding method, comprising:

[0008] Transferring the busbar-less photovoltaic cell sheets and the welding ribbons to a pre-welding device, heating the welding ribbons so that the welding ribbons are pre-fixed on the surfaces of the corresponding busbar-less photovoltaic cell sheets to obtain a cell string;

[0009] The battery string is transferred to the bottom of the heating and pressing device, and the heating and pressing device is controlled to move to contact the front film layer on the battery string, and the front film layer is heated and pressurized to obtain a battery string.

[0010] Optionally, pre-fixing the welding ribbon on the surface of the corresponding busbar-less photovoltaic cell comprises:

[0011] The busbar-less photovoltaic cell is transferred to the bottom of the heating device, and a pre-fixed adhesive film is placed on the front of the busbar-less photovoltaic cell. The pre-fixed adhesive film pre-fixes the welding ribbon on the front surface of the cell under the action of the heating device, and the pre-fixed adhesive film forms a front film layer on the cell string;

[0012] The step of heating and pressurizing the front film layer includes: smoothing the pre-fixed adhesive film.

[0013] Optionally, the battery string and the back film layer are synchronously transferred to a heating and pressing device, and a front film layer is applied on the battery string.

[0014] Optionally, controlling the heating and pressurizing device to heat and pressurize the front film layer includes:

[0015] The heating and pressurizing device is controlled to heat and pressurize at least two adjacent busbar-less photovoltaic cell sheets in the cell string at the same time.

[0016] Optionally, the number of the front film layers on the battery string is at least two.

[0017] Optionally, synchronously transferring the battery array and the back film layer to a heating and pressurizing device includes:

[0018] The battery string and a back film layer are synchronously transferred to a heating and pressing device. The back film layer covers all the busbar-free photovoltaic cells in the battery string. The back film layer is arranged in a long strip along the extension direction of the battery string.

[0019] Optionally, synchronously transferring the battery array and the back film layer to a heating and pressurizing device includes:

[0020] The battery string and at least two back film layers are transferred to a heating and pressing device, wherein each back film layer covers at least two busbar-free photovoltaic cells in the battery string, and the back film layer is arranged in a long strip along the extension direction of the battery string. At least two back film layers are transferred in sequence. When the transfer of the first back film layer starts, the transfer of the battery string starts, and when the transfer of the last back film layer ends, the transfer of the battery string ends.

[0021] Optionally, before synchronously transferring the battery string and the back film layer to the heating and pressurizing device, the method further includes:

[0022] The string cutting device is controlled to cut the solder strips on the battery strings to obtain battery strings of target length.

[0023] Optionally, the method further comprises providing a busbar-less photovoltaic cell sheet, wherein the line width of some fine grid lines of the busbar-less photovoltaic cell sheet is greater than the line width of other fine grid lines;

[0024] Heating so that the welding ribbon is pre-fixed on the surface of the corresponding busbar-free photovoltaic cell comprises:

[0025] Under the action of the pre-welding device, metal melting occurs at the contact position between the thin grid lines with larger line width on the busbar-less photovoltaic cell and the welding ribbon, and the welding ribbon is pre-fixed on the busbar-less photovoltaic cell.

[0026] Optionally, also include:

[0027] The fine grid lines at the edges of the busbar-free photovoltaic cell are thickened, and at least two fine grid lines with larger line widths are provided on each side edge. The edges of the busbar-free photovoltaic cell are located at both ends of the busbar-free photovoltaic cell along the extension direction of the cell string.

[0028] The present application provides a busbar-free photovoltaic cell string welding device, comprising:

[0029] A pre-welding device, a heating and pressing device, and a conveying device, wherein in the conveying direction of the battery string, the pre-welding device is located upstream of the heating and pressing device, and the conveying device is located downstream of the pre-welding device;

[0030] The pre-welding device is used to pre-fix the welding ribbon on the surface of the corresponding busbar-less photovoltaic cell sheet to form a cell string;

[0031] The heating and pressurizing device is used to heat and pressurize the front film layer on the battery string.

[0032] Optionally, the transmission device is used to synchronously transmit the back film layer and the battery string to the heating and pressurizing device.

[0033] Optionally, also include:

[0034] A press tool picking device, used to remove the press tooling located on the battery string after pre-welding is completed;

[0035] In the conveying direction of the battery string, the press picking device is located between the pre-welding device and the heating and pressing device.

[0036] The present application provides a method for welding busbar-free photovoltaic cells in series, comprising: transferring busbar-free photovoltaic cell sheets and welding ribbons to a pre-welding device, heating the welding ribbons so that the welding ribbons are pre-fixed on the surfaces of the corresponding busbar-free photovoltaic cell sheets to obtain a cell string; transferring the cell string to the bottom of a heating and pressing device, controlling the heating and pressing device to move to contact the front film layer on the cell string, and heating and pressurizing the front film layer to obtain a cell string.

[0037] It can be seen that the string welding method of the present application first pre-fixes the main grid-free photovoltaic cell and the welding ribbon, and then coats the front and back of the pre-fixed cell string, and then heats and pressurizes the front film layer to form a cell string. Since the pre-fixation has been carried out before the front film layer is heated and pressurized, there is no need to place a press tool on the front during heating and pressurization, which avoids the phenomenon of uneven heating, thereby avoiding the problem of film bubbling and cold welding. At the same time, heating and pressurizing can also ensure the welding quality between the welding ribbon and the main grid-free cell, reducing the occurrence of cold welding and broken grid. Moreover, by applying pressure to the front, the situation of bubbling of the front film layer can also be avoided. In addition, after pre-welding, the heating and pressurizing device heats and pressurizes the front film layer, which can also prevent the welding ribbon from deviating.

[0038] In addition, the present application also provides a busbar-free photovoltaic cell string welding device having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] FIG1 is a flow chart of a busbar-free photovoltaic cell string welding method according to an embodiment of the present application;

[0041] FIG2 is a second flow chart of a busbar-free photovoltaic cell string welding method provided in an embodiment of the present application;

[0042] FIG3 is a schematic structural diagram of a busbar-free photovoltaic cell string welding device provided in an embodiment of the present application;

[0043] FIG4 is a schematic diagram of a partial structure of a busbar-less photovoltaic cell string welding device provided in an embodiment of the present application;

[0044] FIG5 is a schematic diagram of the connection between a welding ribbon and a battery cell in a battery string provided by an embodiment of the present application;

[0045] FIG6 is a schematic structural diagram of a battery string provided in an embodiment of the present application;

[0046] FIG7 is a schematic structural diagram of a heating and pressurizing device provided in an embodiment of the present application;

[0047] FIG8 and FIG9 are schematic diagrams of different coating quantities on a battery string provided in an embodiment of the present application;

[0048] FIG10 is a schematic structural diagram of a photovoltaic cell string welding device provided in an embodiment of the present application;

[0049] FIG11 is a schematic structural diagram of a battery string provided in an embodiment of the present application;

[0050] FIG12 is a flow chart of a photovoltaic cell string welding process performed by a string welding device according to an embodiment of the present application;

[0051] In the figure, 1. heating and pressurizing device, 2. battery string, 3. heating part, 4. first conveyor belt, 5. support rod, 6. press tool, 7. press picking device, 8. main grid photovoltaic cell, 81. fine grid line, 82. widened fine grid line, 9. welding tape, 10. first heating base plate, 11. string cutting device, 12. second conveyor belt, 13. vacuum adsorption hole, 14. back film layer, 15. front film layer, 16. second heating base plate, 17. driving component, 18. elastic body, 19. box, 20. heating body, 21. air inlet, 22. lifting screw, 23. bracket, 24. battery string, 25. heating device, 26. conveyor belt, 27. heating base plate, 28. first carrier film, 29. low-temperature welding tape, 30. battery cell, 31. second carrier film. DETAILED DESCRIPTION

[0052] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present application.

[0053] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0054] As mentioned in the background section, the current string soldering process generally involves backside film application, backside soldering ribbon, busbar-less photovoltaic cell placement, frontside soldering ribbon, frontside film application, and then press tooling. The frontside requires a press tool for securing the cells. This reflects infrared radiation, resulting in uneven heating and, in turn, cold solder joints, broken busbars, and film blistering.

[0055] In view of this, the present application provides a busbar-less photovoltaic cell string welding method, which may include:

[0056] Transferring the busbar-less photovoltaic cell sheets and the welding ribbons to a pre-welding device, heating the welding ribbons so that the welding ribbons are pre-fixed on the surfaces of the corresponding busbar-less photovoltaic cell sheets to obtain a cell string;

[0057] The battery string is transferred to the bottom of the heating and pressing device, and the heating and pressing device is controlled to move to contact the front film layer on the battery string, and the front film layer is heated and pressurized to obtain a battery string.

[0058] Based on the above embodiment, in one embodiment of the present application, pre-fixing the welding ribbon on the surface of the corresponding busbar-less photovoltaic cell comprises:

[0059] The busbarless photovoltaic cell is transferred to the bottom of the heating device, and a pre-fixed adhesive film is placed on the front of the busbarless photovoltaic cell. Under the action of the heating device, the pre-fixed adhesive film pre-fixes the welding ribbon on the front surface of the cell, and the pre-fixed adhesive film forms the front film layer on the cell string; there is no doubt that the welding ribbon is pre-fixed on the front surface of the cell by heating the pre-fixed adhesive film, and the above-mentioned cell is a busbarless photovoltaic cell.

[0060] The step of heating and pressurizing the front film layer includes: smoothing the pre-fixed adhesive film.

[0061] Specifically, in this embodiment, the string welding method includes:

[0062] The battery cell is transferred to the bottom of the heating device, and a soldering ribbon and a pre-fixing adhesive film are placed on the front of the battery cell. The pre-fixing adhesive film pre-fixes the soldering ribbon on the front surface of the battery cell under the action of the heating device;

[0063] The battery cell passing through the heating device is then transferred to the bottom of the heating and pressing device. The heating and pressing device moves downward, and the elastic body in the heating and pressing device contacts the pre-fixed adhesive film on the front of the battery cell to smooth the pre-fixed adhesive film.

[0064] When the battery cell is under the heating device, there is a press tool on the surface of the battery cell. The part not covered by the press tool and the edge of the pre-fixed film may have poor pre-fixation, shrinkage wrinkles, etc., and continue to flow through the heating and pressurizing device to directly smooth the pre-fixed film, reducing the possibility of abnormal defects in the subsequent transfer, layout and lamination processes.

[0065] Based on the above embodiment, in another embodiment of the present application, referring to FIG1 , a busbar-less photovoltaic cell string welding method may include:

[0066] Step S101: transferring busbar-less photovoltaic cell sheets and welding ribbons to a pre-welding device, heating the welding ribbons so that the welding ribbons are pre-fixed on the surfaces of the corresponding busbar-less photovoltaic cell sheets to obtain cell strings.

[0067] In this embodiment, the soldering tape may be a low-temperature soldering tape, which may be a soldering tape made of a copper-based tin-bismuth-lead material with a bismuth content of 14-26.

[0068] The welding ribbon is pre-fixed to the fine grid lines on the main grid-less photovoltaic cell.

[0069] It should be noted that in this embodiment, there is no limitation on the position where the welding ribbon is pre-fixed on the busbar-less photovoltaic cell. For example, it can be at the edge of the busbar-less photovoltaic cell, or in the middle area between the edges.

[0070] The number of busbar-free photovoltaic cells in a battery string can be set as needed and is not limited in this embodiment.

[0071] Step S102: synchronously transferring the battery string and the back film layer to a heating and pressing device, and laying a front film layer on the battery string.

[0072] The front film layer can be completed by using a front film layer laying device to pull the front film layer to the upper side of the battery string and cover the front film layer on the front side of the battery string.

[0073] It should be noted that the number of front film layers may be determined according to circumstances and is not limited in this embodiment.

[0074] As one possible implementation, the number of front film layers can be one, with one front film layer covering all busbar-less photovoltaic cells in the cell string. The front film layer is arranged in a long strip along the extension direction of the cell string. That is, only one film layer is provided on the front side of the cell string. Rather than requiring the film layer to be larger than the cell string, the front film layer is slightly smaller than the cell string. The edges of the cell string slightly extend beyond the front film layer, and the front and rear edges of the busbar-less photovoltaic cells at the ends also extend beyond the front film layer.

[0075] In another embodiment, the front film layer on the cell string is provided as at least two sheets, each covering at least two busbar-less photovoltaic cells in the cell string. The front film layer is provided in a long strip along the extension direction of the cell string. This can improve both the front film coating speed and the front film coating accuracy.

[0076] It should also be noted that the number of back film layers may vary depending on the situation and is not limited in this embodiment. The number of back film layers may be one or more than two.

[0077] As an implementation method, the battery string and the back film layer are synchronously transferred to the heating and pressurizing device, including:

[0078] The battery string and a back film layer are synchronously transferred to a heating and pressing device. The back film layer covers all the busbar-free photovoltaic cells in the battery string. The back film layer is arranged in a long strip along the extension direction of the battery string.

[0079] In this embodiment, only one film layer is provided on the back side of the battery string, and the size of the back film layer does not exceed that of the battery string. The size of the back film layer is slightly smaller than that of the battery string, and the edges on both sides of the battery string slightly extend beyond the back film layer, and the front / rear edges of the main-grid-less photovoltaic cell also extend beyond the back film layer.

[0080] The transmission of the battery string is not entirely driven by the back film layer. The vacuum adsorption holes can also directly adsorb the position of the busbar-free photovoltaic cell that is not blocked by the film.

[0081] In related art, individual solar cells are individually coated, and the front and back film layers on each cell have two ends. These layers are prone to separation from the cell at these ends, increasing the probability of separation between the front and back films in a cell string. When a single film layer is applied to the front and back of a cell string, the film layer has only two ends along the length of the cell string, significantly reducing the probability of separation between the film layer and the busbar-less photovoltaic cell compared to related art.

[0082] As another possible implementation method, synchronously transferring the battery string and the back film layer to a heating and pressurizing device includes:

[0083] The battery string and at least two back film layers are transferred to a heating and pressing device, each back film layer covers at least two busbar-free photovoltaic cells in the battery string, and the back film layer is arranged in a long strip along the extension direction of the battery string. At least two back film layers are transferred in sequence, and at least two back film layers are transferred in sequence. When the first back film layer starts to be transferred, the battery string transfer starts, and when the last back film layer is transferred, the battery string transfer ends.

[0084] For example, when there are two back film layers, the first back film layer is transported first, and then the second back film layer is transported. The front end of the first back film layer in the transport direction is transported synchronously with the front end of the battery string in the transport direction to the location of the heating and pressing device. After the first layer is transported, the second layer is transported, and the end of the second back film layer in the transport direction is transported synchronously with the end of the battery string in the transport direction to the location of the heating and pressing device.

[0085] When the number of front film layers and back film layers is more than two, the segmented positions of the front film layers and the segmented positions of the back film layers are preferably staggered to improve the stability of the battery string.

[0086] Step S103: controlling the heating and pressurizing device to move to contact the front film layer on the battery string, and heating and pressurizing the front film layer to obtain a battery string.

[0087] When the cell strings are transferred to the heating and pressurizing device, there are no pressurizing fixtures attached to the strings. The heating and pressurizing device directly contacts the front film layer, applying heat and pressurization. Heating the front film layer from the front side prevents uneven heating, which in turn prevents blistering and cold solder joints. Front-side pressurization reduces cold solder joints, broken grids, and blistering on the front side, while also applying pressure between the back film layer and the busbar-less photovoltaic cell.

[0088] The back side of the battery string is heated by the second heating base plate.

[0089] In order to improve the efficiency of string welding, as an implementation method, controlling the heating and pressurizing device to heat and pressurize the front film layer includes:

[0090] The heating and pressurizing device is controlled to heat and pressurize at least two adjacent busbar-less photovoltaic cell sheets in the cell string at the same time.

[0091] The string welding method of this embodiment first pre-fixes the main grid photovoltaic cell and the welding ribbon, then coats the front and back of the pre-fixed cell string, and then heats and pressurizes the front film layer to form a cell string. Since the pre-fixing has been carried out before the front film layer is heated and pressurized, there is no need to place a press tool on the front during heating and pressurization, which avoids the phenomenon of uneven heating, thereby avoiding the problem of film bubbling and cold welding. At the same time, heating and pressurizing can also ensure the welding quality between the welding ribbon and the main grid photovoltaic cell, reducing the occurrence of cold welding and broken grid. Moreover, by applying pressure to the front, the situation of bubbling of the front film layer can also be avoided. In addition, after pre-welding, the heating and pressurizing device heats and pressurizes the front film layer, which can also prevent the welding ribbon from shifting. Moreover, in this application, the welding ribbon and the fine grid line are welded before the front film layer and the back film layer are laid, which can solve the problem of cold welding that cannot be tested by front electroluminescence.

[0092] Based on the above embodiment, in one embodiment of the present application, when the number of busbar-less photovoltaic cells in a cell string is greater than the number of cells required in the cell string, before synchronously transferring the cell string and the back film layer to the heating and pressurizing device, the following steps may be further included:

[0093] The string cutting device is controlled to cut the solder strips on the battery strings to obtain battery strings of target length.

[0094] In the direction of transport of the battery strings, the string cutting device is located between the pre-welding device and the heating and pressing device. It cuts the welding ribbons between the busbar-less photovoltaic cells to obtain battery strings of the required length.

[0095] In this embodiment, by providing a string cutting device for cutting, the battery strings can be automatically cut with high speed and efficiency, thus saving labor costs.

[0096] Referring to FIG. 2 , based on any of the above embodiments, in one embodiment of the present application, a busbar-less photovoltaic cell string welding method may include:

[0097] Step S201: providing a busbar-less photovoltaic cell, wherein the line width of some fine grid lines of the busbar-less photovoltaic cell is greater than the line width of other fine grid lines.

[0098] It should be noted that, in this embodiment, there is no limitation on the position of the thin grid lines with a relatively wide line width on the busbar-less photovoltaic cell, and the positions can be set arbitrarily.

[0099] For example, the wider grid lines can be located at the edges of the busbar-less photovoltaic cell, which are located at both ends of the busbar-less photovoltaic cell along the extension direction of the cell string, or in the middle area between the edges.

[0100] It should also be noted that the present embodiment does not limit the number of thin gate lines with a relatively wide line width and can be set arbitrarily, for example, two, three, four, five, six, etc.

[0101] Step S202: The busbar-less photovoltaic cell sheet and the welding ribbon are transferred to a pre-welding device. Under the action of the pre-welding device, metal melting occurs at the contact position between the thin grid lines with larger line width on the busbar-less photovoltaic cell sheet and the welding ribbon. The welding ribbon is pre-fixed on the busbar-less photovoltaic cell sheet to obtain a cell string.

[0102] By pre-fixing the soldering ribbon to thin grid lines with a larger line width, the difficulty of pre-fixing can be reduced and the firmness of pre-fixing can be improved.

[0103] Step S203: Controlling the string cutting device to cut the solder ribbons on the battery strings to obtain battery strings of target length.

[0104] Step S204: The battery string of target length and the back film layer are synchronously transferred to a heating and pressing device, and the front film layer is laid on the battery string.

[0105] Step S205: controlling the heating and pressurizing device to move to contact the front film layer on the battery string, and heating and pressurizing the front film layer to obtain a battery string.

[0106] Based on the above embodiment, in one embodiment of the present application, the busbar-less photovoltaic cell string welding method may further include:

[0107] The fine grid lines at the edges of the busbar-free photovoltaic cell are thickened, and at least two fine grid lines with larger line widths are provided on each side edge. The edges of the busbar-free photovoltaic cell are located at both ends of the busbar-free photovoltaic cell along the extension direction of the cell string.

[0108] At least two thin grid lines with relatively large line widths are provided on each side edge of the busbar-less photovoltaic cell sheet, which can improve the pre-fixation stability of the welding strips on each side edge.

[0109] The present application also provides a busbar-free photovoltaic cell string welding device, please refer to Figures 3 and 4, including:

[0110] A pre-welding device, a heating and pressing device 1 and a transmission device, wherein in the conveying direction of the battery string, the pre-welding device is located upstream of the heating and pressing device 1, and the transmission device is located downstream of the pre-welding device;

[0111] The pre-welding device is used to pre-fix the welding ribbon on the surface of the corresponding busbar-less photovoltaic cell sheet to form a cell string;

[0112] The heating and pressurizing device 1 is used to heat and pressurize the front film layer 15 on the battery string.

[0113] On the basis of the above embodiment, in one embodiment of the present application, the transmission device is used to synchronously transmit the back film layer 14 and the battery string to the heating and pressurizing device 1 .

[0114] The pre-welding device comprises a heating part 3 for heating so as to melt the welding strip and the thin grid lines on the busbar-less photovoltaic cell sheet, and pre-weld and fix them.

[0115] The pre-welding device also includes a first conveyor belt 4, a support rod 5, and a press tool 6, wherein the first conveyor belt 4 is used to transfer the main grid-free photovoltaic cell 8 to the lower side of the heating part 3; the support rod 5 is used to fix the heating part 3, and a position adjustment component is provided on the support rod 5. By adjusting the position adjustment component, the position of the heating part 3 on the support rod 5 is changed, and then the height of the heating part 3 from the main grid-free photovoltaic cell 8 is adjusted; the press tool 6 is used to fix the welding ribbon 9 on the main grid-free photovoltaic cell 8.

[0116] During the pre-welding process, a press tool 6 is placed on the busbar-less photovoltaic cell 8. Before the heating and pressurizing device 1 is activated, the press tool 6 needs to be removed from the busbar-less photovoltaic cell 8. The present application does not limit the method for removing the press tool 6, and the method can be selected at will.

[0117] As an implementable method, the pressing tool 6 can be removed manually.

[0118] As another possible implementation method, the busbar-less photovoltaic cell string welding device may further include:

[0119] A press tool picking device 7, used to remove the press tooling located on the battery string after pre-welding is completed;

[0120] In the conveying direction of the battery string, the press picking device is located between the pre-welding device and the heating and pressing device 1 .

[0121] When the press picking device 7 is provided, the press tooling 6 on the busbar-less photovoltaic cell 8 can be automatically picked up, which saves manpower and is highly efficient.

[0122] Of two adjacent busbarless photovoltaic cell sheets 8 , the front surface of one busbarless photovoltaic cell sheet 8 is connected to the back surface of the other busbarless photovoltaic cell sheet 8 via a welding ribbon 9 , thereby forming a cell string 24 , as shown in FIG5 .

[0123] The schematic diagram of the structure of the cell string 24 formed by the busbarless photovoltaic cell 8 is shown in Figure 6. Fine grid lines 81 are distributed on the busbarless photovoltaic cell 8. The pre-welding device electrically connects the welding ribbon 9 to the fine grid lines 81 at the edge of the busbarless photovoltaic cell 8. During pre-welding, the number of fine grid lines 81 welded between the welding ribbon 9 and each end of the busbarless photovoltaic cell 8 can be one to three. To improve welding reliability, the fine grid lines 81 pre-welded to each end of the busbarless photovoltaic cell 8 and the welding ribbon 9 use widened fine grid lines 82.

[0124] The widening of the thin grid line 82 can be done by widening the entire width of the thin grid line 81, or by widening the area where it is welded to the welding strip 9. This is not limited in this application. The widening size can be set as needed and is not limited in this application.

[0125] The busbarless photovoltaic cell string welding equipment also includes a second conveyor belt 12 and a second heating base plate 16. The second conveyor belt 12 is used to transport the pre-welded cell strings 24 to the bottom side of the heating and pressurizing device 1. The second heating base plate 16 is located below the second conveyor belt 12 and is used to heat the back side of the cell strings 24. The second conveyor belt 12 and the first conveyor belt 4 have the same conveying direction.

[0126] It should be noted that the present application does not limit the structure of the heating and pressurizing device 1 , as long as it can achieve the heating and pressurizing functions on the front film layer 15 of the busbar-less photovoltaic cell 8 .

[0127] As an embodiment, the heating and pressurizing device 1 includes a box body 19 with an opening, an elastomer 18 and a heating and pressurizing part; the heating and pressurizing part is used to heat the elastomer 18 and apply pressure to the elastomer 18; the elastomer 18 is located at the opening of the box body 19 and is sealed with the box body 19, and the elastomer 18 is used to contact the front of the battery string 24.

[0128] The elastomer 18 has a certain temperature and pressure under the action of the heating and pressurizing part. When the elastomer contacts the front film layer 15, it can apply pressure to the front film layer 15, so that the front film layer 15 is tightly and comprehensively attached to the welding ribbon 9 and the surface of the main grid photovoltaic cell 8. The welding ribbon 9 and the main grid photovoltaic cell 8 are of different heights. Since the elastomer has a certain elasticity, it can ensure that the front film layer 15 is tightly attached to the welding ribbon 9 and the main grid photovoltaic cell 8. At the same time, the elastomer conducts heat to the welding ribbon 9, causing the welding ribbon 9 to melt, and then better weld with the fine grid lines 81 on the main grid photovoltaic cell 8 to avoid the occurrence of cold welding.

[0129] The material of the elastic body 18 includes but is not limited to silicone or rubber.

[0130] It should also be noted that the heating and pressurizing part is not limited in this application and can be set according to actual conditions.

[0131] In one possible implementation manner of the present application, the heating and pressurizing portion includes a liquid heat-conducting medium, and the box body 19 is provided with a liquid inlet.

[0132] The liquid heat-conducting medium is heated to a certain temperature, and is filled into the box through the liquid inlet and contacts the elastomer. On the one hand, it can transfer heat to the elastomer, and on the other hand, the liquid heat-conducting medium has its own weight and applies pressure to the elastomer through its weight.

[0133] The liquid heat transfer medium may be heat transfer oil or the like.

[0134] In another possible implementation of the present application, as shown in Figure 7, the heating and pressurizing part includes a heating body 20 and an inflation device; the heating body 20 is located in the box body 19; the box body 19 is provided with an air inlet 21, and the inflation device is connected to the air inlet 21 to introduce gas into the box body 19.

[0135] The heating body 20 can heat the inner layer of the elastic body 18, thereby increasing the temperature of the elastic body 18. The heating body 20 can be arranged on the upper wall of the box body 19, opposite to the elastic body 18.

[0136] The inflation valve in the inflation device is opened, and the inflation device introduces gas, which can be compressed air, into the box body 19 through the air inlet 21, increasing the pressure in the box body 19 and exerting pressure on the elastic body 18. When the pressure in the box body 19 reaches a certain value (for example, 0.3 MPa), the inflation valve closes and maintains the pressure.

[0137] The heating body 20 includes but is not limited to at least one of an infrared heating lamp, a resistance wire heating tube, a mica radiation heating plate, and an array laser heater.

[0138] The heating body 20 can be evenly distributed in the box body 19 and can evenly heat all parts of the inner surface of the elastic body 18 so that the temperature of the elastic body 18 is uniform.

[0139] As an implementable embodiment, the photovoltaic cell string welding equipment may also include: a bracket 23, a driving component 17 and a lifting screw 22; the lifting screw 22 is connected to the heating and pressurizing device 1 and the driving component 17; the bracket 23 is used to fix the box 19; the driving component 17 is used to drive the lifting screw 22 to adjust the lifting and lowering of the heating and pressurizing device 1.

[0140] The driving component 17 may be a servo motor.

[0141] Because the heating and pressurizing device 1 applies pressure and heat to the front film layer 15 of the battery array 24, the elastic body 18 needs to contact the surface of the front film layer 15. When the heating and pressurizing process is completed, the elastic body 18 needs to separate from the front film layer 15. In this embodiment, the driving component 17 drives the lifting screw 22, which drives the box 19 to move up and down, thereby adjusting the contact between the elastic body 18 and the front film layer 15. This embodiment can automatically adjust the contact and separation between the elastic body 18 and the front film layer 15, which is very convenient and quick.

[0142] The transmission device can be a vacuum adsorption hole 13 provided on the second conveyor belt 12; the second conveyor belt 12 adsorbs the back film layer 14 from the lower side of the second conveyor belt 12 through the vacuum adsorption hole 13, and transports one end of the back film layer 14 to the end position of the main grid-free photovoltaic cell 8, and synchronously transports the back film layer 14 and the battery string 24 to the lower side of the heating and pressurizing device 1 to lay the back film layer 14 on the back side of the battery string 24.

[0143] The second conveyor belt 12 simultaneously transports the back film layer 14 and the battery string 24 to the bottom of the heating and pressing device 1, completing the laying of the back film layer 14. There is no need to perform a separate step of laying the back film layer 14, saving process time and improving the production capacity of the string welding equipment.

[0144] The string welding equipment of this embodiment first pre-fixes the main grid-free photovoltaic cell and the welding ribbon, then coats the front and back of the pre-fixed cell string, and then heats and pressurizes the front film layer 15 to form a cell string. Since the pre-fixing has been carried out before the front film layer 15 is heated and pressurized, there is no need to place a press tool on the front during heating and pressurization, which avoids the phenomenon of uneven heating, thereby avoiding the problem of film bubbling and cold welding. At the same time, heating and pressurizing can also ensure the welding quality between the welding ribbon and the main grid-free cell, reducing the occurrence of cold welding and broken grid. Moreover, by applying pressure to the front, the situation of bubbling of the front film layer 15 can also be avoided. In addition, after pre-welding, the heating and pressurizing device 1 heats and pressurizes the front film layer 15, which can also prevent the welding ribbon from shifting. Moreover, in this application, the welding ribbon and the fine grid line are welded before the front film layer 15 and the back film layer 14 are laid, which can solve the problem of cold welding that cannot be tested by front electroluminescence.

[0145] As an embodiment, the number of front film layer 15 and back film layer 14 applied to a battery string 2 can be one sheet, that is, the battery string 2 is fully coated, as shown in FIG8 , with one front film layer 15 on the front and one back film layer 14 on the back. In this case, when the second conveyor belt 12 conveys the back film layer 14, it conveys one end of the back film layer 14 to the head position of the battery string 2, so that the back film layer 14 is applied to the back of the battery string 2 at one time.

[0146] The head of the battery string 2 , ie, the battery string 24 , is the first end to enter the second conveyor belt 12 in the conveying direction.

[0147] As another possible implementation, two or three film layers may be applied on the front and back sides of the battery string 2 .

[0148] When two film layers are respectively applied on the front and back of a battery string 24 , as shown in FIG9 , there are two front film layers 15 on the front and two back film layers 14 on the back.

[0149] On the basis of the above embodiment, in one embodiment of the present application, as shown in FIG3 , the pre-welding device may further include:

[0150] The first heating base plate 10 is located below the first conveyor belt 4 and is used to heat and keep the busbar-less photovoltaic cell pieces 8 warm during the pre-welding process of the cell strings 24 .

[0151] By setting up the first heating base plate 10, it plays an auxiliary heating and heat preservation role when pre-welding the welding ribbon 9 and the fine grid line 81 at the end of the busbar-free photovoltaic cell 8, which can improve the pre-welding speed and accelerate the string welding efficiency.

[0152] On the basis of any of the above embodiments, in one embodiment of the present application, the busbar-less photovoltaic cell string welding device may further include:

[0153] A string cutting device 11, used for cutting the solder ribbon 9 to obtain a battery string 2 of a target length;

[0154] In the conveying direction of the battery strings 24 , the string cutting device 11 is located between the pre-welding device and the heating and pressurizing device 1 .

[0155] The string cutting device 11 includes a cutting tool. Please refer to Figure 3. The string cutting device 11 is set between the pre-welding device and the heating and pressing device 1 to cut the welding ribbons 9 between the main grid-free photovoltaic cell pieces 8 to obtain a cell string 2 of the required length.

[0156] In this embodiment, by providing the string cutting device 11, the battery strings 24 can be automatically cut with high speed and efficiency, thus saving labor costs.

[0157] On the basis of any of the above embodiments, in one embodiment of the present application, the busbar-less photovoltaic cell string welding device may further include:

[0158] The front film layer laying device is used to pull the front film layer 15 to the upper side of the battery string 24 and cover the front film layer 15 on the front side of the battery string 24.

[0159] The front film layer 15 is automatically laid by the front film layer laying device, which is simple to operate, saves labor costs, and improves the string welding efficiency.

[0160] The present application also provides a photovoltaic cell string welding device, please refer to Figures 7, 10 to 11, which includes a heating device 25 and a heating and pressing device 1; the heating device 25 is used to preheat the front surface of the cell string 2; the heating and pressing device 1 is used to pressurize and heat the front surface of the cell string 2;

[0161] In the conveying direction of the battery string 2, the heating and pressurizing device 1 is located downstream of the heating device 25;

[0162] The heating and pressurizing device 1 includes a box body 19 with an opening, an elastic body 18 and a heating and pressurizing part; the heating and pressurizing part is used to heat the elastic body 18 and apply pressure to the elastic body 18; the elastic body 18 is located at the opening of the box body 19 and is sealed with the box body 19, and the elastic body 18 is used to contact the front of the battery string 2.

[0163] It should be noted that the photovoltaic cell string welding equipment also includes a conveyor belt 26, a heating base plate 27 and a press tool 6; the heating device 25 and the heating and pressurizing device 1 are both located above the conveyor belt 26; the heating base plate 27 is located below the conveyor belt 26, and is used to heat the back of the cell string 2; the press tool 6 is used to be placed on the front of the cell string 2.

[0164] The heating device 25 can be any of an infrared heating lamp, a resistance wire heating tube, a mica radiation heating plate, or an array laser heater, and is not limited in this application. When heating the battery string 2, the heating device 25 maintains a certain distance from the upper surface of the battery string 2, i.e., heating is performed through air. The heating and pressurizing portion provides contact heating to the battery string 2.

[0165] The heating base plate 27 is in a state of being heated all the time, and each heating base plate 27 can be set to a different heating temperature according to process requirements.

[0166] A schematic diagram of a battery string 2 is shown in Figure 11 , comprising a first carrier film 28, a low-temperature solder ribbon 29, a battery cell 30, a low-temperature solder ribbon 29, and a second carrier film 31 stacked sequentially from bottom to top. The first carrier film 28 is located on the back of the battery cell 30, and the second carrier film 31 is located on the front of the battery cell 30. The battery string 2 before being pressurized and heated by the heating and pressurizing device 1 is shown in area A of Figure 11 , while the battery string after being pressurized and heated by the heating and pressurizing device 1 is shown in area B of Figure 11 .

[0167] The battery string 2 is placed on the conveyor belt 26, that is, the first carrier film 28 on the back of the battery string 2 is in contact with the conveyor belt 26 and the heating base plate 27. Due to the weight pressure of the press tool 6, the first carrier film 28 is closely attached to the conveyor belt 26 and the heating base plate 27, and the low-temperature welding tape 29 has been preliminarily fused with the battery cell 30, so the low-temperature welding tape 29 on the back and the battery cell 30 are well welded.

[0168] The conveying direction of the battery string 2 is also the conveying direction of the conveyor belt 26. After the battery string 2 passes through the heating device 25 and before reaching the heating and pressing device 1, the pressing tool 6 needs to be removed from the battery string 2.

[0169] The elastomer 18 has a certain temperature and pressure under the action of the heating and pressurizing part. When the elastomer 18 contacts the second carrier film 31 on the front of the battery string 2, pressure can be applied to the second carrier film 31, so that the second carrier film 31 is tightly and comprehensively attached to the surface of the low-temperature welding tape 29 and the battery cell 30. The low-temperature welding tape 29 and the battery cell 30 are of different heights. Since the elastomer 18 has a certain elasticity, it can ensure that the second carrier film 31 is tightly attached to the low-temperature welding tape 29 and the battery cell 30. At the same time, the elastomer 18 transfers heat to the low-temperature welding tape 29, so that the low-temperature welding tape 29 melts, and then better welds with the grid line on the battery cell 30 to avoid the occurrence of cold welding. The temperature of the outer surface of the elastomer 18 can be between 100°C and 120°C, and the pressure on the elastomer 18 can be 0.3MPa.

[0170] The material of the elastic body 18 includes but is not limited to silicone or rubber.

[0171] It should be pointed out that the present application does not limit the heating and pressurizing part, and it can be set according to actual conditions.

[0172] In one possible implementation manner of the present application, the heating and pressurizing portion includes a liquid heat-conducting medium, and the box body 19 is provided with a liquid inlet.

[0173] The liquid heat-conducting medium is heated to a certain temperature, and is filled into the box 19 through the liquid inlet and contacts the elastomer 18. On the one hand, it can transfer heat to the elastomer 18, and on the other hand, the liquid heat-conducting medium itself has weight and applies pressure to the elastomer 18 through its weight.

[0174] The liquid heat transfer medium may be heat transfer oil or the like.

[0175] In another possible implementation of the present application, as shown in Figure 7, the heating and pressurizing part includes a heating body 20 and an inflation device; the heating body 20 is located in the box body 19; the box body 19 is provided with an air inlet 21, and the inflation device is connected to the air inlet 21 to introduce gas into the box body 19.

[0176] The heating body 20 can heat the inner layer of the elastic body 18, thereby increasing the temperature of the elastic body 18. The heating body 20 can be arranged on the upper wall of the box body 19, opposite to the elastic body 18.

[0177] The inflation valve in the inflation device is opened, and the inflation device introduces gas, which can be compressed air, into the box body 19 through the air inlet 21, increasing the pressure in the box body 19 and exerting pressure on the elastic body 18. When the pressure in the box body 19 reaches a certain value (for example, 0.3 MPa), the inflation valve closes and maintains the pressure.

[0178] The heating body 20 includes but is not limited to at least one of an infrared heating lamp, a resistance wire heating tube, a mica radiation heating plate, and an array laser heater.

[0179] The heating body 20 can be evenly distributed in the box body 19 and can evenly heat all parts of the inner surface of the elastic body 18 so that the temperature of the elastic body 18 is uniform.

[0180] To better control the pressure exerted by the heating and pressurizing unit on the elastic body 18, as one possible embodiment, the photovoltaic cell string soldering apparatus may further include a pressure sensor disposed within the housing 19 for measuring the pressure within the housing 19. The pressure within the housing 19 is also the pressure exerted on the elastic body 18. When the pressure exerted on the elastic body 18 reaches a set pressure threshold, the pressurization can be stopped.

[0181] In order to obtain the temperature of the elastic body 18, in one embodiment of the present application, the photovoltaic cell string soldering device may further include: a temperature sensor provided on the outer surface of the elastic body 18, for measuring the temperature of the elastic body 18. When the temperature of the elastic body 18 rises to a set temperature threshold, heating of the elastic body 18 may be stopped.

[0182] In this embodiment, a heating device 25 and a heating and pressurizing device 1 are provided. The heating device 25 preheats the front of the battery string 2, and then the heating and pressurizing device 1 pressurizes and heats the front of the battery string 2. The elastomer 18 and the box body 19 form a sealed whole, and the heating and pressurizing part makes the elastomer 18 have a certain temperature and pressure. The elastic component applies pressure to the front of the battery string 2 to prevent bubbling of the front supporting film, and because the elastic component is elastic, the supporting film on the front of the battery string 2 is tightly fitted with the battery cell 30, thereby making the low-temperature solder strip 29 between the front supporting film and the battery cell 30 in close contact with the grid line on the battery cell 30. At the same time, the elastic component heats the front of the battery string 2, causing the low-temperature solder strip 29 to melt, thereby improving the welding effect with the grid line on the battery cell 30, and avoiding problems such as displacement of the low-temperature solder strip 29 caused by EL (Electroluminescent) test solder joint lamination.

[0183] On the basis of the above embodiments, in one embodiment of the present application, please refer to Figure 7, the photovoltaic cell string welding equipment may also include: a bracket 23, a driving component 17 and a lifting screw 22; the lifting screw 22 is connected to the heating and pressurizing device 1 and the driving component 17; the bracket 23 is used to fix the box body 19; the driving component 17 is used to drive the lifting screw 22 to adjust the lifting and lowering of the heating and pressurizing device 1.

[0184] The driving component 17 may be a servo motor.

[0185] Because the heating and pressurizing device 1 applies pressure and heat to the battery string 2, the elastic body 18 needs to contact the upper surface of the battery string 2. When the heating and pressurizing process is completed, the elastic body 18 needs to separate from the battery string 2. In this embodiment, the driving component 17 drives the lifting screw 22, which drives the box 19 to move up and down, thereby adjusting the contact between the elastic body 18 and the surface of the battery string 2. This embodiment can automatically adjust the contact and separation between the elastic body 18 and the battery string 2, which is very convenient and quick.

[0186] Please refer to Figure 10. Based on any of the above embodiments, in one embodiment of the present application, the photovoltaic cell string welding equipment may further include: a press picking device 7; in the conveying direction of the cell string 2, the press picking device 7 is located between the heating device 25 and the heating and pressurizing device 1.

[0187] When the heating device 25 heats the battery string 2, the press tool 6 presses on the upper surface of the battery string 2. When the heating and pressurizing device 1 heats the battery string 2, the press tool 6 is no longer on the upper surface of the battery string 2. After the heating device 25 completes heating, the press tool 6 on the upper surface of the battery string 2 is removed from the battery string 2 by the press tool picking device 7, eliminating the need for manual operation, saving manpower, and being very convenient.

[0188] The following is an introduction to the process of the photovoltaic cell string welding equipment of this application.

[0189] Refer to Figure 12. The conveyor advances once, placing the first carrier film, pulling and laying the low-temperature solder tape, placing the crystalline silicon cell, placing the second carrier film, and placing the press tool. During the second (even-numbered) advance of the conveyor, the heating device heats the battery string in the air. The box in the heating and pressurizing device moves downward to contact the surface of the second carrier film, applying pressure and heat. The press tool on the upper surface of the battery string is removed before the heating and pressurizing device applies pressure and heat. The welding base plate is continuously heated, heating the first carrier film and low-temperature solder tape on the lower surface of the battery string.

[0190] Among them, the heating device preheats the front of the battery string, and then the heating and pressurizing device pressurizes and heats the front of the battery string. The elastomer and the box form a sealed whole, and the heating and pressurizing part makes the elastomer have a certain temperature and pressure. The elastic component applies pressure to the front of the battery string to prevent bubbling of the front supporting film, and because the elastic component is elastic, the supporting film on the front of the battery string is tightly fitted with the battery cell, thereby making the low-temperature welding strip between the front supporting film and the battery cell in close contact with the grid line on the battery cell. At the same time, the elastic component heats the front of the battery string, causing the low-temperature welding strip to melt, thereby improving the welding effect with the grid line on the battery cell.

[0191] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0192] The above is a detailed introduction to the busbar-free photovoltaic cell string welding method and busbar-free photovoltaic cell string welding device provided by this application. This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only used to help understand the solution and core ideas of this application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the scope of protection of this application.

Claims

1. A busbar-less photovoltaic cell string welding method, characterized in that: include: Transferring the busbar-less photovoltaic cell sheets and the welding ribbons to a pre-welding device, heating the welding ribbons so that the welding ribbons are pre-fixed on the surfaces of the corresponding busbar-less photovoltaic cell sheets to obtain a cell string; The battery string is transferred to the bottom of the heating and pressing device, and the heating and pressing device is controlled to move to contact the front film layer on the battery string, and the front film layer is heated and pressurized to obtain a battery string.

2. The busbar-free photovoltaic cell string welding method according to claim 1, wherein: The step of pre-fixing the welding ribbon on the surface of the corresponding busbar-free photovoltaic cell comprises: The busbar-less photovoltaic cell is transferred to the bottom of the heating device, and a pre-fixed adhesive film is placed on the front of the busbar-less photovoltaic cell. The pre-fixed adhesive film pre-fixes the welding ribbon on the front surface of the cell under the action of the heating device, and the pre-fixed adhesive film forms a front film layer on the cell string; The step of heating and pressurizing the front film layer includes: smoothing the pre-fixed adhesive film.

3. The busbar-free photovoltaic cell string welding method according to claim 1, wherein: The battery string and the back film layer are synchronously transferred to a heating and pressing device, and a front film layer is laid on the battery string.

4. The busbar-free photovoltaic cell string welding method according to claim 3, wherein: Controlling the heating and pressurizing device to heat and pressurize the front film layer includes: The heating and pressurizing device is controlled to heat and pressurize at least two adjacent busbar-less photovoltaic cell sheets in the cell string at the same time.

5. The busbar-less photovoltaic cell string welding method according to claim 3, characterized in that: The front film layers on the battery string are provided with at least two layers.

6. The busbar-less photovoltaic cell string welding method according to claim 3, wherein: Synchronously transferring the battery string and the back film layer to a heating and pressurizing device includes: The battery string and a back film layer are synchronously transferred to a heating and pressing device. The back film layer covers all the busbar-free photovoltaic cells in the battery string. The back film layer is arranged in a long strip along the extension direction of the battery string.

7. The busbar-less photovoltaic cell string welding method according to claim 3, wherein: Synchronously transferring the battery string and the back film layer to a heating and pressurizing device includes: The battery string and at least two back film layers are transferred to a heating and pressing device, wherein each back film layer covers at least two busbar-free photovoltaic cells in the battery string, and the back film layer is arranged in a long strip along the extension direction of the battery string. At least two back film layers are transferred in sequence. When the transfer of the first back film layer starts, the transfer of the battery string starts, and when the transfer of the last back film layer ends, the transfer of the battery string ends.

8. The busbar-less photovoltaic cell string welding method according to claim 3, wherein: Before synchronously transferring the battery string and the back film layer to the heating and pressurizing device, the method further includes: The string cutting device is controlled to cut the solder strips on the battery strings to obtain battery strings of target length.

9. The busbar-less photovoltaic cell string welding method according to claim 3, wherein: The invention also includes providing a busbar-free photovoltaic cell sheet, wherein the line width of some fine grid lines of the busbar-free photovoltaic cell sheet is greater than the line width of other fine grid lines; Heating so that the welding ribbon is pre-fixed on the surface of the corresponding busbar-free photovoltaic cell comprises: Under the action of the pre-welding device, metal melting occurs at the contact position between the thin grid lines with larger line width on the busbar-less photovoltaic cell and the welding ribbon, and the welding ribbon is pre-fixed on the busbar-less photovoltaic cell.

10. The busbar-less photovoltaic cell string welding method according to claim 9, characterized in that: Also includes: The fine grid lines at the edges of the busbar-free photovoltaic cell are thickened, and at least two fine grid lines with larger line widths are provided on each side edge. The edges of the busbar-free photovoltaic cell are located at both ends of the busbar-free photovoltaic cell along the extension direction of the cell string.

11. A busbar-less photovoltaic cell string welding device, characterized in that: include: A pre-welding device, a heating and pressing device, and a conveying device, wherein in the conveying direction of the battery string, the pre-welding device is located upstream of the heating and pressing device, and the conveying device is located downstream of the pre-welding device; The pre-welding device is used to pre-fix the welding ribbon on the surface of the corresponding busbar-less photovoltaic cell sheet to form a cell string; The heating and pressurizing device is used to heat and pressurize the front film layer on the battery string.

12. The busbar-less photovoltaic cell string welding device according to claim 11, characterized in that: The transmission device is used to synchronously transmit the back film layer and the battery string to the heating and pressurizing device.

13. The busbar-less photovoltaic cell string welding device according to claim 12, characterized in that: Also includes: A press tool picking device, used to remove the press tooling located on the battery string after pre-welding is completed; In the conveying direction of the battery string, the press picking device is located between the pre-welding device and the heating and pressing device.

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