Main-grid-free photovoltaic cell series welding method and main-grid-free photovoltaic cell series welding equipment

Abstract

The invention relates to the field of photovoltaic cell production, and discloses a main-grid-free photovoltaic cell series welding method and main-grid-free photovoltaic cell series welding device.The method comprises the steps that main-grid-free photovoltaic cell pieces and welding strips are conveyed to a pre-welding device, heating is conducted, so that the welding strips are pre-fixed to the surfaces of the corresponding main-grid-free photovoltaic cell pieces, and cell series arrays are obtained; synchronously transmitting the battery series and the back film layer to a heating and pressurizing device, and laying a front film layer on the battery series; and controlling the heating and pressurizing device to move to be in contact with the front film layer on the battery string, and heating and pressurizing the front film layer to obtain the battery string. The method comprises the following steps of: pre-fixing a battery piece and a welding strip, laminating, and heating and pressurizing a front film layer. During heating and pressurizing, a hold-down tool does not need to be placed on the front face, uneven heating is avoided, the problems of film bubbling and pseudo soldering are avoided, the welding quality can be guaranteed, and the conditions of pseudo soldering and grid breaking are reduced. And heating and pressurizing are carried out after pre-welding, so that the solder strip can be prevented from deviating.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic cell production, in particular to a method and device for string welding of a busbar-free photovoltaic cell. BACKGROUND

[0002] When the busbar-free photovoltaic cell is connected in series to form a cell string, the process sequence generally includes back film layer laying-back solder strip-busbar-free photovoltaic cell placement-front solder strip-front film layer laying-press tool positioning. The front film layer is heated by an infrared lamp, which is a heat transfer from the outside to the inside. Since the press tool is used to fix the front film layer and the solder strip, the infrared lamp heating is a radiation irradiation method, and the press tool causes uneven heating temperature on the surface of the busbar-free photovoltaic cell, thereby causing film layer bubbling and virtual welding between the grid lines and the solder strip.

[0003] In addition, the above-mentioned front film layer and back film layer are laid for a single busbar-free photovoltaic cell, and the film layer will also produce pre-crosslinking during the heating process, thereby causing the front film layer to adhere to the press and the back film layer to adhere to the belt, increasing the risk of solder strip deviation, virtual welding and other abnormalities.

[0004] Therefore, how to solve the above technical problems should be the focus of attention of those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a method and device for string welding of a busbar-free photovoltaic cell to avoid the problems of virtual welding, broken grid and front film layer bubbling in the cell string.

[0006] To solve the above technical problems, the present application provides a method for string welding of a busbar-free photovoltaic cell, comprising:

[0007] The busbar-free photovoltaic cell and the solder strip are transported to a pre-welding device, and heating is performed to pre-fix the solder strip on the surface of the corresponding busbar-free photovoltaic cell, thereby obtaining a cell string.

[0008] The cell string and the back film layer are synchronously transported to a heating and pressing device, and the front film layer is laid on the cell string.

[0009] The heating and pressing device is controlled to move into contact with the front film layer on the cell string, and the front film layer is heated and pressed, thereby obtaining a cell string.

[0010] Optionally, the heating and pressing of the front film layer by the heating and pressing device comprises:

[0011] The heating and pressing device simultaneously heats and presses at least two adjacent busbar-free photovoltaic cells in the cell string.

[0012] Optionally, the front film layer on the battery string is provided as at least two.

[0013] Optionally, synchronously conveying the battery string and the back film layer to the heating and pressing device comprises:

[0014] Synchronously conveying the battery string and a back film layer to the heating and pressing device, the back film layer covering all the gridless photovoltaic cell pieces in the battery string, the back film layer being provided in a strip shape along the extension direction of the battery string.

[0015] Optionally, synchronously conveying the battery string and the back film layer to the heating and pressing device comprises:

[0016] Synchronously conveying the battery string and at least two back film layers to the heating and pressing device, each of the back film layers covering at least two gridless photovoltaic cell pieces in the battery string, the back film layers being provided in a strip shape along the extension direction of the battery string, the at least two back film layers being conveyed in sequence, the battery string being conveyed starting when the first back film layer starts to be conveyed, and the battery string being conveyed ending when the last back film layer ends to be conveyed.

[0017] Optionally, before synchronously conveying the battery string and the back film layer to the heating and pressing device, the method further comprises:

[0018] Controlling the string-by-string cutting device to cut the solder strip on the battery string to obtain a battery string with a target length.

[0019] Optionally, the method further comprises providing the gridless photovoltaic cell piece, a part of the fine grid lines of the gridless photovoltaic cell piece having a line width greater than that of other fine grid lines.

[0020] The pre-fixing of the solder strip on the surface of the corresponding gridless photovoltaic cell piece by heating comprises:

[0021] The pre-fixing of the solder strip on the surface of the corresponding gridless photovoltaic cell piece by heating comprises:

[0022] Optionally, the method further comprises:

[0023] Thickening the fine grid lines at the edges of the gridless photovoltaic cell piece, at least two fine grid lines with a greater line width being provided at each side edge, the edges of the gridless photovoltaic cell piece being located at both ends of the gridless photovoltaic cell piece along the extension direction of the battery string.

[0024] The application discloses a gridless photovoltaic cell string welding device, which comprises:

[0025] A pre-welding device, a heating and pressing device, and a conveying device, 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;

[0026] The pre-welding device is used to pre-fix the welding strip on the surface of the corresponding busbar-free photovoltaic cell to form a battery string list;

[0027] The heating and pressing device is used to heat and press the front film layer on the battery string list;

[0028] The conveying device is used to synchronously convey the back film layer to the heating and pressing device with the battery string list.

[0029] Optionally, it further comprises:

[0030] A press pick-up device is used to take away the press tool located on the battery string list after the pre-welding is completed;

[0031] In the conveying direction of the battery string, the press pick-up device is located between the pre-welding device and the heating and pressing device.

[0032] The application provides a busbar-free photovoltaic cell string welding method, which comprises the following steps: conveying a busbar-free photovoltaic cell and a welding strip to a pre-welding device, heating to pre-fix the welding strip on the surface of the corresponding busbar-free photovoltaic cell to obtain a battery string list; synchronously conveying the battery string list and a back film layer to a heating and pressing device, and laying a front film layer on the battery string list; controlling the heating and pressing device to move to contact the front film layer on the battery string list, and heating and pressing the front film layer to obtain a battery string.

[0033] It can be seen that the string welding method of the application first pre-fixes the busbar-free photovoltaic cell and the welding strip, then covers the front and back film layers on the battery string list formed by pre-fixing, and then heats and presses the front film layer to form a battery string. Since the pre-fixing is performed before the heating and pressing of the front film layer, the press tool does not need to be placed on the front during the heating and pressing, so that the phenomenon of uneven heating is avoided, thereby avoiding the problems of film layer bubbling and virtual welding. In addition, the heating and pressing can also ensure the welding quality between the welding strip and the busbar-free cell, and reduce the occurrence of virtual welding and broken grid. Moreover, by applying pressure to the front, the situation of front film layer bubbling can also be avoided. In addition, after pre-welding, the heating and pressing device heats and presses the front film layer, which can also prevent the welding strip from deviating.

[0034] In addition, the application also provides a busbar-free photovoltaic cell string welding device with the above advantages. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0036] Figure 1 The flow of the method for string welding of the main grid-free photovoltaic cell provided by the embodiment of the present application Figure 1 ;

[0037] Figure 2 The flow of the method for string welding of the main grid-free photovoltaic cell provided by the embodiment of the present application Figure 2 ;

[0038] Figure 3 The structural schematic diagram of the string welding device of the main grid-free photovoltaic cell provided by the embodiment of the present application

[0039] Figure 4 The partial structural schematic diagram of the string welding device of the main grid-free photovoltaic cell provided by the embodiment of the present application

[0040] Figure 5 The connection schematic diagram of the welding ribbon and the cell in the cell string provided by the embodiment of the present application

[0041] Figure 6 The structural schematic diagram of the cell string provided by the embodiment of the present application

[0042] Figure 7 The structural schematic diagram of the heating and pressing device provided by the embodiment of the present application

[0043] Figure 8 And Figure 9 The schematic diagram of different film numbers on the cell string provided by the embodiment of the present application

[0044] In the figure, 1, heating and pressing device, 2, cell string, 3, heating part, 4, first conveying belt, 5, supporting rod, 6, pressing tool, 7, pressing pickup device, 8, main grid-free photovoltaic cell, 81, thin grid line, 82, widened thin grid line, 9, welding ribbon, 10, first heating bottom plate, 11, string cutting device, 12, second conveying belt, 13, vacuum adsorption hole, 14, back film layer, 15, front film layer, 16, second heating bottom plate, 17, driving part, 18, elastic body, 19, box body, 20, heating body, 21, air inlet, 22, lifting screw, 23, bracket, 24, cell string row. DETAILED DESCRIPTION

[0045] In order to make the person skilled in the art better understand the present application, the present application is further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0046] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0047] As described in the background section, the process sequence in the current string welding process generally includes back film layer laying-back solder ribbon-no main grid photovoltaic cell placement-front solder ribbon-front film layer laying-press tool positioning. The front surface needs to be fixed by the press tool, which will reflect infrared rays, resulting in uneven heating, and further causing problems such as virtual welding, broken grid and film layer bubbling.

[0048] Therefore, the present application provides a no main grid photovoltaic cell string welding method, please refer to Figure 1 , comprising:

[0049] Step S101: transmitting a no main grid photovoltaic cell and a solder ribbon to a pre-welding device, heating to make the solder ribbon pre-fixed on the surface of the corresponding no main grid photovoltaic cell, and obtaining a cell string.

[0050] In the embodiment, the solder ribbon can be a low-temperature solder ribbon. The low-temperature solder ribbon can use a solder ribbon with a bismuth content of 14-26 copper-based tin bismuth lead material.

[0051] The solder ribbon is pre-fixed between the solder ribbon and the fine grid lines on the no main grid photovoltaic cell.

[0052] It should be pointed out that the position of the solder ribbon pre-fixed on the no main grid photovoltaic cell in the embodiment is not limited, for example, it can be at the edge of the no main grid photovoltaic cell, or in the middle region between the edges.

[0053] The number of no main grid photovoltaic cells in the cell string can be set as needed, which is not limited in the embodiment.

[0054] Step S102: synchronously transmitting the cell string and a back film layer to a heating and pressing device, and laying a front film layer on the cell string.

[0055] The front film layer can be pulled to the upper side of the cell string by using a front film layer laying device, and the front film layer is covered on the front surface of the cell string to complete.

[0056] It should be noted that the number of front surface film layers can be determined as appropriate, and is not limited in the present embodiment.

[0057] As one possible implementation, the number of front surface film layers can be one, and one front surface film layer covers all the busbar-free photovoltaic cell pieces in the battery string. The front surface film layer is arranged in a strip shape along the extension direction of the battery string. That is, only one film layer is arranged on the front surface of the battery string, and the size of the film layer does not exceed the battery string. The size of the front surface film layer is slightly smaller than the battery string, the edges of the battery string slightly exceed the front surface film layer, and the front end / rear end edges of the busbar-free photovoltaic cell pieces at the ends also exceed the front surface film layer.

[0058] As another possible implementation, the front surface film layers on the battery string are arranged as at least two, and each front surface film layer covers at least two busbar-free photovoltaic cell pieces in the battery string. The front surface film layers are arranged in a strip shape along the extension direction of the battery string. At this time, the front surface film speed and the front surface film precision can be improved at the same time.

[0059] It should be further noted that the number of back surface film layers can be determined as appropriate, and is not limited in the present embodiment. The number of back surface film layers can be one or more than two.

[0060] As one possible implementation, the battery string and the back surface film layer are synchronously transmitted to the heating and pressing device, which comprises:

[0061] The battery string and one back surface film layer are synchronously transmitted to the heating and pressing device. The back surface film layer covers all the busbar-free photovoltaic cell pieces in the battery string, and the back surface film layer is arranged in a strip shape along the extension direction of the battery string.

[0062] In this embodiment, only one film layer is arranged on the back surface of the battery string, and the size of the back surface film layer does not exceed the battery string. The size of the back surface film layer is slightly smaller than the battery string, the edges of the battery string slightly exceed the back surface film layer, and the front end / rear end edges of the busbar-free photovoltaic cell pieces at the ends also exceed the back surface film layer.

[0063] The transmission of the battery string is not completely driven by the back surface film layer, and the vacuum suction holes can directly suck the positions of the busbar-free photovoltaic cell pieces that are not covered by the film.

[0064] In the related art, each cell piece is individually coated with a film, and the front film layer and the back film layer on each cell piece have two ends. The front film layer and the back film layer are prone to separation at the port, and the probability of separation of the front film layer and the back film layer in the cell string is relatively high. When a whole film layer is attached to the front and back of the cell string, the film layer has only two ports in the length direction of the cell string, which is significantly lower than the probability of separation of the film layer from the main grid-free photovoltaic cell piece in the related art.

[0065] As another implementable manner, the cell string row and the back film layer are synchronously transmitted to the heating and pressing device, which comprises:

[0066] The cell string row and at least two back film layers are transmitted to the heating and pressing device, each of the back film layers covers at least two main grid-free photovoltaic cell pieces in the cell string row, the back film layer is arranged in a strip shape along the extension direction of the cell string row, and at least two of the back film layers are transmitted in sequence. When the transmission of the first back film layer starts, the transmission of the cell string row starts, and when the transmission of the last back film layer ends, the transmission of the cell string row ends.

[0067] 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 transportation direction is synchronously transported to the location of the heating and pressing device with the front end of the cell string row in the transportation direction. After the first back film layer is transported, the second back film layer is transported, and the end of the second back film layer in the transportation direction is synchronously transported to the location of the heating and pressing device with the end of the cell string row in the transportation direction.

[0068] When the number of the front film layer and the back film layer is more than two, the segmentation position of the front film layer is preferably staggered with the segmentation position of the back film layer to improve the stability of the cell string.

[0069] Step S103: The heating and pressing device is controlled to move to contact the front film layer on the cell string row and to heat and press the front film layer to obtain a cell string.

[0070] When the cell string row is transmitted to the heating and pressing device, there is no pressing tool on the cell string row. The heating and pressing device directly contacts the front film layer and heats and presses the front film layer. The front film layer is heated on the front side to avoid uneven heating and thus to avoid bubbling or virtual welding. The front side is pressed to reduce the occurrence of virtual welding, broken grid, and bubbling on the front side, and to apply pressure between the back film layer and the main grid-free photovoltaic cell piece.

[0071] The back of the cell string row is heated by the second heating bottom plate.

[0072] In order to improve the efficiency of string welding, as an implementation manner, the heating and pressing device is controlled to heat and press the front film layer, which comprises the following steps:

[0073] The heating and pressing device is controlled to heat and press at least two adjacent bus-bar-free photovoltaic cell pieces in the cell string.

[0074] The string welding method of the embodiment first fixes the bus-bar-free photovoltaic cell pieces and the welding strip, then covers the cell string formed by the fixation with front and back films, heats and presses the front film layer, and forms the cell string. Since the fixation is performed before the heating and pressing of the front film layer, the heating and pressing do not need to place a press tool on the front surface, thereby avoiding the uneven heating and the problems of film layer bubbling and false welding. In addition, the heating and pressing can ensure the welding quality between the welding strip and the bus-bar-free cell pieces, and reduce the false welding and broken grid conditions. In addition, the application of pressure to the front surface can also avoid the bubbling of the front film layer. In addition, after the pre-welding, the heating and pressing of the front film layer by the heating and pressing device can also prevent the welding strip from shifting. In addition, the welding of the welding strip and the fine grid line before the application of the front and back film layers can solve the problem of false welding in the front electroluminescence test.

[0075] On the basis of the above-mentioned embodiments, in an embodiment of the application, when the number of bus-bar-free photovoltaic cell pieces in the cell string is greater than the number of cell pieces required in the cell string, before the cell string and the back film layer are synchronously transmitted to the heating and pressing device, the method can further comprise the following steps:

[0076] The string cutting device is controlled to cut the welding strip on the cell string to obtain a cell string with a target length.

[0077] The string cutting device is located between the pre-welding device and the heating and pressing device in the conveying direction of the cell string. The welding strip between the bus-bar-free photovoltaic cell pieces is cut to obtain a cell string with a required length.

[0078] In the embodiment, the string cutting device is set to cut, which can automatically realize the cutting of the cell string, has high speed and efficiency, and saves labor cost.

[0079] Please refer to Figure 2 On the basis of any of the above-mentioned embodiments, in an embodiment of the application, the bus-bar-free photovoltaic cell string welding method can comprise the following steps:

[0080] Step S201: providing bus-bar-free photovoltaic cell pieces, the line width of part of the fine grid lines of the bus-bar-free photovoltaic cell pieces being greater than that of other fine grid lines.

[0081] It should be noted that the position of the fine grid line with wider line width on the no-main-grid photovoltaic cell in the embodiment is not limited, and can be set by itself.

[0082] For example, the fine grid line with wider line width can be at the edge of the no-main-grid photovoltaic cell, and the edge of the no-main-grid photovoltaic cell is located at both ends of the no-main-grid photovoltaic cell along the extension direction of the cell string.

[0083] It should be further noted that the number of fine grid lines with wider line width in the embodiment is not limited, and can be set by itself. For example, it can be two, three, four, five, six, etc.

[0084] Step S202: The no-main-grid photovoltaic cell and the solder strip are transmitted to the pre-welding device, and under the action of the pre-welding device, the contact position between the fine grid line with wider line width on the no-main-grid photovoltaic cell and the solder strip is subjected to metal melting, the solder strip is pre-fixed on the no-main-grid photovoltaic cell, and the cell string is obtained.

[0085] By pre-fixing the solder strip and the fine grid line with wider line width, the difficulty of pre-fixing can be reduced, and the firmness of pre-fixing can be improved.

[0086] Step S203: The cutting device is controlled to cut the solder strip on the cell string, and the cell string with a target length is obtained.

[0087] Step S204: The cell string with a target length and the back film layer are transmitted to the heating and pressing device synchronously, and the front film layer is laid on the cell string.

[0088] Step S205: The heating and pressing device is controlled to move to contact the front film layer on the cell string, and the front film layer is heated and pressed, and the cell string is obtained.

[0089] On the basis of the above embodiment, in an embodiment of the present application, the no-main-grid photovoltaic cell string welding method can further include:

[0090] The fine grid line at the edge of the no-main-grid photovoltaic cell is thickened, and at least two fine grid lines with wider line width are arranged on each side edge, and the edge of the no-main-grid photovoltaic cell is located at both ends of the no-main-grid photovoltaic cell along the extension direction of the cell string.

[0091] At least two fine grid lines with wider line width are arranged on each side edge of the no-main-grid photovoltaic cell, which can improve the pre-fixing stability of the solder strip on each side edge.

[0092] The present application also provides a no-main-grid photovoltaic cell string welding device, please refer to Figure 3 and Figure 4 , comprising:

[0093] A pre-welding device, a heating and pressing device 1, and a conveying device, in the conveying direction of the battery string, the pre-welding device is located upstream of the heating and pressing device 1, and the conveying device is located downstream of the pre-welding device;

[0094] The pre-welding device is used to pre-fix the welding strip on the surface of the corresponding gridless photovoltaic cell to form a battery string;

[0095] The heating and pressing device 1 is used to heat and press the front film layer 15 on the battery string;

[0096] The conveying device is used to convey the back film layer 14 to the heating and pressing device 1 synchronously with the battery string.

[0097] The pre-welding device comprises a heating part 3 for heating to melt the welding strip and the fine grid line on the gridless photovoltaic cell, and the pre-welding is fixed.

[0098] The pre-welding device further comprises a first conveying belt 4, a support rod 5, and a pressing tool 6, wherein the first conveying belt 4 is used to convey the gridless 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 the support rod 5 is provided with a position adjusting part, and the position of the heating part 3 on the support rod 5 is changed by adjusting the position adjusting part, so as to adjust the height of the heating part 3 from the gridless photovoltaic cell 8; and the pressing tool 6 is used to fix the welding strip 9 on the gridless photovoltaic cell 8.

[0099] In the pre-welding process, the pressing tool 6 is placed on the gridless photovoltaic cell 8, and the pressing tool 6 needs to be taken off from the gridless photovoltaic cell 8 before the action of the heating and pressing device 1. The way of taking off the pressing tool 6 is not limited in the present application, and can be selected by itself.

[0100] As an implementable manner, the pressing tool 6 can be taken off manually.

[0101] As another implementable manner, the gridless photovoltaic cell string welding equipment can further comprise:

[0102] A pressing pickup device 7 is used to take away the pressing tool on the battery string after the pre-welding is completed;

[0103] In the conveying direction of the battery string, the pressing pickup device is located between the pre-welding device and the heating and pressing device 1.

[0104] When the pressing pickup device 7 is set, the pressing tool 6 on the gridless photovoltaic cell 8 can be automatically picked up, which saves manpower and has high efficiency.

[0105] Two adjacent busbar-free photovoltaic cells 8, the front side of one busbar-free photovoltaic cell 8 is connected to the back side of the other busbar-free photovoltaic cell 8 by a solder strip 9, thereby forming a cell string 24, as shown in Figure 5 .

[0106] The structure diagram of the cell string 24 formed by the busbar-free photovoltaic cells 8 is shown in Figure 6 , the busbar-free photovoltaic cells 8 are distributed with fine grid lines 81, and the pre-welding device electrically connects the solder strip 9 and the fine grid line 81 at the edge of the busbar-free photovoltaic cell 8. Among them, the number of solder strips 9 welded with the fine grid line 81 at each end of the busbar-free photovoltaic cell 8 can be 1-3. In order to improve the reliability of welding, the fine grid line 81 pre-welded with the solder strip 9 at each end of the busbar-free photovoltaic cell 8 uses a widened fine grid line 82.

[0107] The widened fine grid line 82 can widen the width of the whole fine grid line 81, or locally widen the area welded with the solder strip 9, which is not limited in the present application. The size of the widening is set as needed, which is not limited in the present application.

[0108] The busbar-free photovoltaic cell string welding equipment also includes a second conveying belt 12 and a second heating bottom plate 16, the second conveying belt 12 is used to convey the pre-welded cell string 24 to the lower side of the heating and pressing device 1, and the second heating bottom plate 16 is located at the lower side of the second conveying belt 12 and is used to heat the back of the cell string 24. The conveying direction of the second conveying belt 12 is consistent with that of the first conveying belt 4.

[0109] It should be noted that the structure of the heating and pressing device 1 is not limited in the present application, as long as it can realize the functions of heating and pressing the front film layer 15 of the busbar-free photovoltaic cell 8.

[0110] As an implementable manner, the heating and pressing device 1 includes a box body 19 with an opening, an elastic body 18, and a heating and pressing part; the heating and pressing part is used to heat 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 cell string 24.

[0111] The elastomer 18 has a certain temperature and pressure under the action of the heating and pressing part. When the elastomer contacts the front film layer 15, the front film layer 15 can be pressed to tightly and fully adhere to the solder strip 9 and the surface of the busbar-free photovoltaic cell 8. The solder strip 9 is not in high level with the busbar-free photovoltaic cell 8, and the elastomer has a certain elasticity, so that the front film layer 15 can be tightly adhered to the solder strip 9 and the busbar-free photovoltaic cell 8. At the same time, the elastomer conducts heat to the solder strip 9, so that the solder strip 9 is melted, and then better welded to the fine grid line 81 on the busbar-free photovoltaic cell 8, avoiding the occurrence of virtual welding.

[0112] The material of the elastomer 18 includes but is not limited to silicone or rubber.

[0113] It should be further pointed out that the heating and pressing part is not limited in the present application, and can be set according to the actual situation.

[0114] In an embodiment of the present application, the heating and pressing part includes a liquid heat-conducting medium, and the box 19 is provided with a liquid inlet.

[0115] The liquid heat-conducting medium is heated to a certain temperature, and the liquid heat-conducting medium is filled into the box through the liquid inlet and contacts the elastomer. On the one hand, the heat can be transferred to the elastomer, and on the other hand, the liquid heat-conducting medium itself has a weight, and the pressure is applied to the elastomer by the weight.

[0116] The liquid heat-conducting medium can be heat-conducting oil or the like.

[0117] In another embodiment of the present application, as shown in Figure 7 the heating and pressing part includes a heating body 20 and an inflation device; the heating body 20 is located in the box 19; the box 19 is provided with an air inlet 21, and the inflation device is connected with the air inlet 21 to introduce gas into the box 19.

[0118] The heating body 20 can heat the inner layer of the elastomer 18, so that the elastomer 18 is heated. The heating body 20 can be arranged on the upper wall in the box 19 and arranged opposite to the elastomer 18.

[0119] The inflation valve in the inflation device is opened, the inflation device introduces gas into the box 19 through the air inlet 21, the gas can be compressed air, the pressure in the box 19 is increased, and the pressure is applied to the elastomer 18. When the pressure in the box 19 reaches a certain value (for example, 0.3 MPa), the inflation valve is closed and the pressure is maintained.

[0120] 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 a face array laser heater.

[0121] The heating body 20 can be uniformly distributed in the box 19, and can uniformly heat the inner surface of the elastomer 18, so that the temperature of the elastomer 18 is uniform.

[0122] As an implementation manner, the photovoltaic cell string welding device can further comprise a support 23, a driving component 17 and a lifting screw rod 22; the lifting screw rod 22 is connected with the heating and pressing device 1 and the driving component 17; the support 23 is used for fixing the box 19; and the driving component 17 is used for driving the lifting screw rod 22, so as to adjust the lifting of the heating and pressing device 1.

[0123] The driving component 17 can be a servo motor.

[0124] Since the heating and pressing device 1 applies pressure and heating to the front film layer 15 of the cell string 24, the elastomer 18 needs to be in contact with the surface of the front film layer 15, and when the heating and pressing is finished, the elastomer 18 needs to be separated from the front film layer 15. In this embodiment, the driving component 17 drives the lifting screw rod 22 to drive the box 19 to move up and down, so as to adjust the contact between the elastomer 18 and the front film layer 15. In this embodiment, the contact and separation between the elastomer 18 and the front film layer 15 can be automatically adjusted, which is very convenient and fast.

[0125] The transmission device can be a vacuum suction hole 13 arranged on the second conveying belt 12; the second conveying belt 12 sucks the back film layer 14 from the lower side of the second conveying belt 12 through the vacuum suction hole 13, transports one end of the back film layer 14 to the end position of the back grid-free photovoltaic cell 8, and synchronously transports the back film layer 14 and the cell string 24 to the lower side of the heating and pressing device 1, so as to lay the back film layer 14 on the back of the cell string 24.

[0126] The second conveying belt 12 simultaneously transports the back film layer 14 and the cell string 24 to the lower side of the heating and pressing device 1, that is, the laying of the back film layer 14 is completed, and the step of laying the back film layer 14 is not needed, which saves the process time and improves the production capacity of the string welding device.

[0127] The string welding device of the embodiment first pre-fixes the busbar-free photovoltaic cell with the welding strip, then covers the cell string formed by pre-fixing with front and back films, and then heats and presses the front film layer 15 to form the cell string. Since the pre-fixing is performed before the heating and pressing of the front film layer 15, the press tool does not need to be placed on the front during the heating and pressing, thereby avoiding the uneven heating and the problems of film layer bubbling and false welding. Meanwhile, the heating and pressing can also ensure the welding quality between the welding strip and the busbar-free cell, thereby reducing the false welding and broken grid. In addition, the application of pressure to the front can also avoid the bubbling of the front film layer 15. In addition, the heating and pressing of the front film layer 15 by the heating and pressing device 1 after pre-welding can also prevent the welding strip from deviating. In addition, the welding of the welding strip and the fine grid line before the laying of the front film layer 15 and the back film layer 14 can solve the problem of false welding that cannot be tested by the front electroluminescence.

[0128] As an implementation manner, the number of the front film layer 15 and the back film layer 14 laid on a cell string 2 can be one, that is, the cell string 2 is covered with a full film. As shown in Figure 8 , the front has one front film layer 15, and the back has one back film layer 14. At this time, the second conveying belt 12 conveys one end of the back film layer 14 to the head position of the cell string 2 when conveying the back film layer 14, so that the back film layer 14 is laid on the back of the cell string 2 at one time.

[0129] The head of the cell string 2, that is, the cell string 24, enters one end of the second conveying belt 12 in the conveying direction first.

[0130] As another implementation manner, two or three film layers can also be laid on the front and back of the cell string 2.

[0131] When two film layers are laid on the front and back of one cell string 24 respectively, as shown in Figure 9 , the front has two front film layers 15, and the back has two back film layers 14.

[0132] On the basis of the above embodiment, in an embodiment of the application, as shown in Figure 3 , the pre-welding device can further include:

[0133] The first heating bottom plate 10 is located below the first conveying belt 4 and is used for heating and keeping warm the busbar-free photovoltaic cell 8 during the pre-welding of the cell string 24.

[0134] By setting the first heating bottom plate 10, the first heating bottom plate 10 plays a role of auxiliary heating and heat preservation when the welding strip 9 is pre-welded with the fine grid lines 81 at the end of the busbar-free photovoltaic cell 8, so that the pre-welding speed can be improved and the string welding efficiency can be accelerated.

[0135] On the basis of any of the above embodiments, in an embodiment of the present application, the busbar-free photovoltaic cell string welding device can further comprise:

[0136] The string cutting device 11 is used for cutting the welding strip 9 to obtain the cell string 2 with a target length.

[0137] In the conveying direction of the cell string row 24, the string cutting device 11 is located between the pre-welding device and the heating and pressing device 1.

[0138] The string cutting device 11 comprises a cutting tool, please refer to Figure 3 The string cutting device 11 is arranged between the pre-welding device and the heating and pressing device 1, and cuts the welding strip 9 between the busbar-free photovoltaic cells 8 to obtain the cell string 2 with a required length.

[0139] In the embodiment, the string cutting device 11 is arranged, so that the cutting of the cell string row 24 can be automatically realized, the speed is fast, the efficiency is high, and the labor cost is saved.

[0140] On the basis of any of the above embodiments, in an embodiment of the present application, the busbar-free photovoltaic cell string welding device can further comprise:

[0141] The front film layer applying device is used for pulling the front film layer 15 to the upper side of the cell string row 24 and covering the front film layer 15 on the front of the cell string row 24.

[0142] The front film layer 15 is automatically applied by the front film layer applying device, so that the operation is simple, the labor cost is saved, and the string welding efficiency is improved.

[0143] In the description, each embodiment is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other.

[0144] The busbar-free photovoltaic cell string welding method and the busbar-free photovoltaic cell string welding device provided by the present application are described in detail. In this paper, specific examples are applied to describe the principles and implementation modes of the present application. The above description of the embodiments is only used to help understand the scheme and core idea of the present application. It should be pointed out that, for ordinary skilled persons in the technical field, some improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the present application.

Claims

1. A method for stringing photovoltaic cells without a grid, characterized in that, include: The gridless photovoltaic cells and solder ribbons are transferred to a pre-welding device, where heating causes the solder ribbons to be pre-fixed on the surface of the corresponding gridless photovoltaic cells, thus obtaining a cell string; The battery string and the back film layer are synchronously transferred to the heating and pressurizing device, and the front film layer is applied on the battery string; The heating and pressurizing 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 the battery string.

2. The method for stringing photovoltaic cells without a grid as described in claim 1, characterized in that, Controlling the heating and pressurizing device to heat and pressurize the front film layer includes: The heating and pressurizing device is controlled to simultaneously heat and pressurize at least two adjacent gridless photovoltaic cells in the battery string.

3. The method for stringing photovoltaic cells without a grid as described in claim 1, characterized in that, The front film layer on the battery string is configured to be at least two layers.

4. The method for stringing photovoltaic cells without a grid as described in claim 1, characterized in that, The synchronous transfer of the battery array and the back film layer to the heating and pressurizing device includes: The battery string and a back film are synchronously transferred to a heating and pressurizing device. The back film covers all the gridless photovoltaic cells in the battery string and is arranged in a long strip along the extension direction of the battery string.

5. The method for stringing photovoltaic cells without a grid as described in claim 1, characterized in that, The synchronous transfer of the battery array and the back film layer to the heating and pressurizing device includes: The battery string and at least two back film layers are transferred to a heating and pressurizing device. Each back film layer covers at least two gridless photovoltaic cells in the battery string. 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 sequentially. When the transfer of the first back film layer begins, the transfer of the battery string begins. When the transfer of the last back film layer ends, the transfer of the battery string ends.

6. The method for stringing photovoltaic cells without a grid as described in claim 1, characterized in that, Before synchronously transferring the battery array and the back film layer to the heating and pressurizing device, the process also includes: The control string cutting device cuts the solder strips on the battery string to obtain a battery string of the target length.

7. The method for stringing photovoltaic cells without a grid as described in claim 1, characterized in that, It also includes providing a gridless photovoltaic cell, wherein the line width of some fine grid lines in the gridless photovoltaic cell is greater than the line width of other fine grid lines; Heating to pre-fix the solder ribbon onto the surface of the corresponding gridless photovoltaic cell includes: Under the action of the pre-welding device, metal melting occurs at the contact point between the fine grid lines with large line width on the gridless photovoltaic cell and the welding strip, and the welding strip is pre-fixed on the gridless photovoltaic cell.

8. The method for stringing photovoltaic cells without a grid as described in claim 7, characterized in that, Also includes: The fine grid lines at the edges of the gridless 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 gridless photovoltaic cell are located at both ends of the gridless photovoltaic cell along the extension direction of the cell string.

9. A gridless photovoltaic cell stringing device, characterized in that, include: The pre-welding device, the heating and pressurizing device, and the conveying device are located upstream of the heating and pressurizing device and downstream of the pre-welding device in the direction of transporting the battery string. The pre-welding device is used to pre-fix the welding strip onto the surface of the corresponding gridless photovoltaic cell to form a cell string; The heating and pressurizing device is used to heat and pressurize the front film layer on the battery string; The transmission device is used to synchronously transmit the back film layer and the battery array to the heating and pressurizing device.

10. The gridless photovoltaic cell stringing equipment as described in claim 9, characterized in that, Also includes: A clamping device is used to remove the clamping fixture located on the battery string after pre-welding is completed; In the direction of transport of the battery string, the press pick-up device is located between the pre-welding device and the heating and pressurizing device.

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