Solar cell welding method, welding system and series welding method

Abstract

The invention discloses a welding method, a welding system and a series welding method of a solar cell, a first glue point is formed on a first surface of the solar cell by using a printing process, and a platform for bearing the solar cell has relatively high air adsorption capacity, so that the solar cell can be better attached to a first welding strip; therefore, the first welding strip and the first glue point have better binding force. And the second adhesive points are formed on the second surface with smaller tension by using the adhesive dispensing process, so that the second adhesive points wrap the second welding strip and are also attached to the second surface of the solar cell, the tension strength of the second surface of the solar cell can be better improved, the risk that the welding strip on the second surface of the solar cell falls off is reduced, and the service life of the solar cell is prolonged. And the reliability of the solar cell is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaics, and particularly relates to a welding method for solar cell wafers, a welding system and a string welding method. Background Art

[0002] Crystalline silicon solar cell wafers are composed of main grids and secondary grids. The secondary grids are responsible for collecting current and transmitting the current to the main grids, and the main grids are responsible for connecting with the welding tapes and transmitting the current to the welding tapes. Among them, the increase in the number of main grids can improve the cell efficiency and module power, but it will also increase the paste consumption of the main grids and increase the cost. The interconnection technology of the main-grid-free crystalline silicon solar cell wafers cancels the main grids and directly connects the welding tapes with the secondary grids, which can reduce the paste consumption and thus reduce the cost.

[0003] During the battery assembly process, the welding tape offset and the welding tape peel force are two major consideration indicators for its assembly quality. In the prior art, when the welding tape is placed on the light-receiving surface of the cell wafer and welded, a spring pressing block is usually used to fix the welding tape and the cell wafer. When the welding tape is placed on the negative surface of the cell wafer for welding, a platform suction force is usually used to fix the welding tape and the cell wafer. Since the light-receiving surface of the cell wafer uses a spring pressing block to press the welding tape, the number of pressing needles of the spring pressing block is not large and cannot provide an omnidirectional pressure similar to that of the backlight surface; and the pressure at a single point of the spring vibration is small, about 1.5 N, so it is impossible to ensure good adhesion between the welding tape and the light-receiving surface of the cell wafer.

[0004] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art already known to those of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a welding method and a welding system for solar cell wafers, which can better improve the tensile strength of the second surface (light-receiving surface) of the solar cell wafers, reduce the risk of welding tape detachment on the second surface (light-receiving surface) of the cell wafers, and improve the reliability of the solar cell wafers.

[0006] In order to achieve the above purpose, the technical solution provided by a specific embodiment of the present invention is as follows:

[0007] A welding method for solar cell wafers, the welding method comprising the following steps:

[0008] Providing a solar cell wafer, the solar cell wafer having a first surface and a second surface oppositely arranged, a plurality of first secondary grid lines being formed on the first surface, and a plurality of second secondary grid lines being formed on the second surface;

[0009] Form first glue dots distributed in an array on the first surface by using a first sizing method, and fix a plurality of first solder ribbons on the first surface. Each of the first solder ribbons is vertically distributed with respect to the first sub-grid lines and is in contact with a column of the first glue dots;

[0010] Fix a plurality of second solder ribbons on the second surface, and form second glue dots distributed in an array on the second surface by using a second sizing method. Each of the second solder ribbons is vertically distributed with respect to the second sub-grid lines and is in contact with a column of the second glue dots;

[0011] Perform heat treatment on the solar cell to weld the first solder ribbon and the second solder ribbon to the first surface and the second surface respectively.

[0012] In one or more embodiments of the present invention, the first sizing method adopts a printing process.

[0013] In one or more embodiments of the present invention, forming first glue dots distributed in an array on the first surface by using a first sizing method includes:

[0014] Provide a carrier plate on which through holes are formed in an array;

[0015] Fix the carrier plate above the first surface of the solar cell;

[0016] Coat glue on the carrier plate, and print the glue onto the first surface by using a squeegee along a direction perpendicular to the first sub-grid lines.

[0017] In one or more embodiments of the present invention, each of the first glue dots is located between two adjacent first sub-grid lines. The height of each of the first glue dots is less than or equal to the height of the first solder ribbon, and the width of each of the first glue dots is greater than or equal to the width of the first solder ribbon.

[0018] In one or more embodiments of the present invention, fixing a plurality of first solder ribbons on the first surface includes:

[0019] Provide first solder ribbons, and arrange a plurality of the first solder ribbons side by side on a platform;

[0020] Place the first surface of the solar cell facing the platform on the plurality of first solder ribbons, and make it fit with the first solder ribbons under the action of the platform.

[0021] In one or more embodiments of the present invention, the second sizing method adopts a dispensing process.

[0022] In one or more embodiments of the present invention, forming second glue dots distributed in an array on the second surface by using a second sizing method includes:

[0023] Use a solder tape positioning device to press the second solder tape against the second surface of the solar cell, wherein an array of dispensing ports is formed on the solder tape positioning device, and each second solder tape is partially exposed by a corresponding column of the dispensing ports;

[0024] Use a dispensing device to form an array of second glue dots on the second surface of the solar cell, wherein the dispensing device includes a plurality of dispensing tubes arranged in an array, and each dispensing tube corresponds to one of the dispensing ports of the solder tape positioning device.

[0025] In one or more embodiments of the present invention, each second glue dot is located between two adjacent second sub-grid lines, the height of each second glue dot is not less than the height of the second solder tape, the width of each second glue dot is greater than or equal to the width of the second solder tape, and each second glue dot completely covers the second solder tape in the radial direction of the second solder tape.

[0026] In one or more embodiments of the present invention, the heat treatment temperature is 5°C - 30°C higher than the melting points of the first solder tape and the second solder tape, and the heat treatment time is 10s - 40s.

[0027] A specific embodiment of the present invention further provides a welding system for the above-mentioned welding method of a solar cell, the welding system includes a welding positioning device and a dispensing device, the welding positioning device is used to press the second solder tape against the second surface of the solar cell, and the dispensing device is used to form second glue dots on the second surface of the solar cell.

[0028] In one or more embodiments of the present invention, the welding positioning device includes:

[0029] A fixed frame, including two fixed beams arranged opposite to each other, a plurality of cross beams installed between the two fixed beams, and a plurality of vertical beams installed perpendicular to the cross beams;

[0030] Pressing needles, installed on the fixed frame and located at each intersection of the cross beams and the vertical beams;

[0031] Wherein, a through dispensing port is formed on the vertical beam between two adjacent pressing needles.

[0032] In one or more embodiments of the present invention, the dispensing device includes:

[0033] A support plate, on which a plurality of glue storage tubes are arranged in an array, and a plurality of dispensing tubes are arranged in an array below the support plate, and the dispensing tubes are in one-to-one correspondence with the glue storage tubes and are connected in communication;

[0034] A pressure - applying assembly is installed above the support plate. The pressure - applying assembly includes a pressure plate, a plurality of pressure heads arrayed on the bottom surface of the pressure plate, and a driving member for driving the movement of the pressure plate. The pressure heads are arranged in one - to - one correspondence with the glue storage tubes, and the pressure heads can be received in the glue storage tubes and extrude the glue in the glue storage tubes.

[0035] A specific embodiment of the present invention further provides a string - soldering method for solar cells, including the following steps:

[0036] Set the first surface of a solar cell upward, and set a plurality of first glue dots on the first surface by using a first glue - applying method;

[0037] Press the first surface onto a plurality of first solder tapes, and make the first glue dots adhesively bond to the first solder tapes correspondingly;

[0038] Place a plurality of second solder tapes on the second surface of the solar cell, set a plurality of second glue dots on the second surface by using a second glue - applying method, and make the second glue dots adhesively bond to the second solder tapes correspondingly;

[0039] Press the first surface with the first glue dots of another solar cell onto the second solder tape to connect the two solar cells in series.

[0040] In one or more embodiments of the present invention, on the first surface of the solar cell, the number of the first glue dots corresponding to a single first solder tape is 2 - 50.

[0041] In one or more embodiments of the present invention, the first surface is the back - light surface of the solar cell, and the second surface is the light - receiving surface of the solar cell.

[0042] In one or more embodiments of the present invention, before the step of setting a plurality of second glue dots on the second surface by using the second glue - applying method, multi - point pressure is applied to each second solder tape to position it on the second surface, and the pressure at each pressure - applying point does not exceed 2.0 N.

[0043] A specific embodiment of the present invention further provides a string - soldering method for solar cells, including the following steps:

[0044] Set a plurality of first glue dots on the first surface of a solar cell by using a first glue - applying method;

[0045] Set a plurality of second glue dots on the second surface of the solar cell by using a second glue - applying method, and the second glue - applying method is different from the first glue - applying method.

[0046] In one or more embodiments of the present invention, the first sizing method adopts a printing process, and the second sizing method adopts a dispensing process.

[0047] In one or more embodiments of the present invention, in the first sizing method, sizing is only performed on the first surface of one of the solar cells.

[0048] In one or more embodiments of the present invention, in the second sizing method, sizing is simultaneously performed on the second surfaces of at least two of the solar cells.

[0049] In one or more embodiments of the present invention, in the second sizing method, the glue at the second glue point covers the second solder strip laid on the second surface from top to bottom to bond the second solder strip to the second surface.

[0050] In one or more embodiments of the present invention, during the process of the second sizing method, pressure is applied to the surface of the second solder strip to position it on the second surface.

[0051] Compared with the prior art, the welding method, welding system and string welding method of the solar cells of the present invention form the first glue point on the first surface of the solar cell by using a printing process. Since the platform carrying the solar cell has a large air adsorption capacity, it can make the solar cell better fit with the first solder strip, so that the first solder strip and the first glue point have better bonding force. And on the second surface with smaller tensile force, a dispensing process is used to form the second glue point, so that the second glue point wraps the second solder strip and also fits the second surface of the solar cell, which can better improve the tensile strength of the second surface of the solar cell, reduce the risk of the solder strip falling off on the second surface of the solar cell, and improve the reliability of the solar cell.

[0052] The welding method, welding system and string welding method of the solar cells of the present invention ensure the output of the solar cell module end while ensuring the tensile force on the second surface of the solar cell. It can complete the glue point printing, dispensing and string welding of multiple solar cells at one time, can match the rhythm of simultaneous welding of multiple solar cells currently, and ensures the output.

[0053] For the conventional double-sided printing method, after printing on one side of the cell, it needs to go through a section of the production line and then print on the other side, resulting in chipping of the cell after a long movement. The welding method, welding system and string welding method of the solar cells of the present invention perform the dispensing process on the second surface of the cell and the limiting of the cell and the second solder strip by the solder strip positioning device at the same time, thereby reducing the process steps, reducing the movement distance of the cell, preventing chipping of the cell itself, and reducing the loss. Description of the Drawings

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0055] Figure 1 It is a flowchart of the welding method of solar cell wafers in an embodiment of the present invention;

[0056] Figure 2 It is a cross-sectional view of the second adhesive point wrapping the second solder tape in the radial direction of the second solder tape in an embodiment of the present invention;

[0057] Figure 3 It is a schematic structural diagram of the welding system of solar cell wafers in another embodiment of the present invention;

[0058] Figure 4 It is a schematic structural diagram of the solder tape positioning device in the welding system of solar cell wafers in another embodiment of the present invention;

[0059] Figure 5 It is a schematic structural diagram of the dispensing device in the welding system of solar cell wafers in another embodiment of the present invention;

[0060] Figure 6 It is a flowchart of the string welding method of solar cell wafers in an embodiment of the present invention;

[0061] Figure 7 It is a schematic diagram of the process steps of the string welding method of solar cell wafers in an embodiment of the present invention;

[0062] Figure 8 It is a flowchart of the string welding method of solar cell wafers in another embodiment of the present invention. Detailed implementation manners

[0063] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0064] As described in the background art, in the prior art, during the battery assembly process, when welding the solder tape to the backlight side of the battery cell, it is usually fixed by the suction force of the platform. Since the contact area between the battery cell and the platform is large, the pressure between the battery cell and the solder tape under the action of the platform suction force is very large, which helps to improve the adhesive strength between the battery cell and the solder tape. When welding the solder tape to the light-receiving side of the battery cell, a spring pressing block is usually used to press the solder tape. The number of pressing pins of the spring pressing block is not many and cannot provide an all-round pressure similar to that of the backlight side. Moreover, the pressure at a single point of the spring vibration is relatively small, about 1.5 N. Therefore, it is impossible to ensure that the solder tape and the light-receiving side of the battery cell can fit well, resulting in the solder tape tensile force on the light-receiving side of the battery cell being less than the solder tape tensile force on the negative side of the battery cell, which affects the assembly quality of the battery cell.

[0065] Table 1 shows the data table of the tensile force test after welding the solder tape and the battery cell using different UV glues under the same welding process. From the data in Table 1, it can be seen that the tensile force data on the backlight side of different UV glues are all greater than the tensile force data on the light-receiving side. And through multiple tensile experiments, it is found that the detachment occurs between the solder tape and the glue dots. After the tensile force test, the glue dots remain on the battery cell. Therefore, it can be concluded that the adhesive force between the cured glue and the battery cell is greater than the adhesive force between the solder tape and the glue.

[0066] Table 1: Data table of the tensile force test after welding the solder tape and the battery cell using different UV glues under the same welding process

[0067]

[0068] Based on this, the present application provides a welding method, a welding system and a string welding method for a solar cell. A first glue dot is formed on the first surface (backlight side) of the solar cell by a printing process. Since the platform carrying the solar cell has a large air adsorption capacity, it can make the solar cell fit better with the first solder tape, so that the first solder tape and the first glue dot have a better bonding force. And on the second surface (light-receiving side) with a smaller tensile force, a second glue dot is formed by a dispensing process, so that the second glue dot wraps the second solder tape and also fits the second surface (light-receiving side) of the solar cell, which can better improve the tensile strength of the second surface (light-receiving side) of the solar cell, reduce the risk of solder tape detachment on the second surface (light-receiving side) of the solar cell, and improve the reliability of the solar cell.

[0069] Refer to Figure 1 As shown, the welding method for a solar cell in an embodiment of the present invention includes:

[0070] S1, providing a solar cell, the solar cell having a first surface and a second surface arranged opposite to each other, a plurality of first sub-grid lines are formed on the first surface, and a plurality of second sub-grid lines are formed on the second surface;

[0071] S2. On the first surface, form first glue dots distributed in an array by using a first glue application method, and fix multiple first solder ribbons on the first surface. Each first solder ribbon is perpendicularly distributed to the first sub-grid lines and contacts a column of first glue dots.

[0072] S3. Fix multiple second solder ribbons on the second surface, and on the second surface, form second glue dots distributed in an array by using a second glue application method. Each second solder ribbon is perpendicularly distributed to the second sub-grid lines and contacts a column of second glue dots.

[0073] S4. Perform heat treatment on the solar cell to weld the first solder ribbon and the second solder ribbon to the first surface and the second surface respectively.

[0074] Among them, the solar cell in step S1 can be a main-gridless crystalline silicon solar cell. It can be understood that the main-gridless crystalline silicon solar cell can completely have no main grid lines, and the solder ribbons welded to the pads replace the main grid lines in the existing solar cells, or can also retain some main grid lines. The main-gridless crystalline silicon solar cell can be a PERC cell, a TOPCon cell or an HJT cell.

[0075] The melting point of the solder ribbon required for the main-gridless crystalline silicon solar cell is 150°C - 200°C. The tin layer composition on the surface of the solder ribbon is tin-lead, tin-lead-bismuth, tin-bismuth-silver, etc. The specific composition and melting point can be selected according to the type of crystalline silicon solar cell used.

[0076] In step S2, the first glue dots can be formed on the first surface of the solar cell by a printing process, that is, the first glue application method is preferably a printing process. Specifically, the first glue dots can be printed on the first surface of the solar cell through components such as a squeegee and a carrier plate with through holes.

[0077] Exemplarily, step S2 includes:

[0078] Provide a carrier plate with through holes formed in an array distribution thereon; fix the carrier plate above the first surface of the solar cell;

[0079] Coat glue on the carrier plate, and use a squeegee to print the glue onto the first surface along the extension direction perpendicular to the first sub-grid lines of the solar cell to form first glue dots distributed in an array. The glue can be UV glue.

[0080] Preferably, each first glue dot is located between two adjacent first sub-grid lines, and the height of each first glue dot is less than or equal to the height of the first solder ribbon, so as to ensure that the first glue dot does not exceed the height of the first solder ribbon, reduce the overall height of the solar cell, and reduce the subsequent glue film weight. The width of each first glue dot is greater than or equal to the width of the first solder ribbon to ensure that the first glue dot can cover the first solder ribbon.

[0081] Step S2 further includes:

[0082] Providing a first solder tape, and arranging a plurality of first solder tapes side by side on a platform with suction force.

[0083] After forming first glue dots distributed in an array on the first surface of the solar cell by a printing process, the solar cell is flipped so that its first surface faces the platform and is placed on the plurality of pre-placed first solder tapes, and is attached to the first solder tapes under the suction force of the platform. Wherein, each first solder tape is in contact with a column of first glue dots.

[0084] In step S3, after the solar cell is placed on the platform, the cut second solder tape is placed at a specified position on the second surface of the solar cell.

[0085] It can be understood that the second solder tape is usually arranged perpendicular to the second sub-grid line and is horizontally arranged side by side in the extending direction of the second sub-grid line. A solder tape positioning device is used to press the second solder tape against the second surface of the solar cell.

[0086] Wherein, the solder tape positioning device is formed with glue dispensing ports distributed in an array, and each second solder tape is partially exposed by a corresponding column of glue dispensing ports. The glue dispensing ports are used to accommodate the glue outlet pipes of the glue dispensing device, so that the glue droplets flowing out of the glue outlet pipes fall on the second solder tape and the solar cell.

[0087] Furthermore, a glue dispensing device is used to form second glue dots distributed in an array on the second surface of the solar cell. That is, the second glue application method is preferably a glue dispensing process. The glue dispensing device includes a plurality of glue outlet pipes distributed in an array, and each glue outlet pipe corresponds to a glue dispensing port of the solder tape positioning device.

[0088] Exemplarily, when the solar cell moves to directly below the glue dispensing device under the conveyance of the platform, the glue dispensing device descends, and its glue outlet pipe extends into the glue dispensing port of the corresponding solder tape positioning device, and pressure is applied to dot the glue on the second solder tape.

[0089] It can be understood that, as shown in Figure 2 each second glue dot B is also located between two adjacent second sub-grid lines, the height of each second glue dot B is not less than the height of the second solder tape C, the width of each second glue dot B is greater than or equal to the width of the second solder tape C, and each second glue dot B completely covers and wraps the second solder tape C in the radial direction of the second solder tape C.

[0090] The second glue dot is arranged to completely wrap the second welding strip radially, which can change the tensile force between the second welding strip and the solar cell from only the adhesion force between the second glue dot and the second welding strip in the original process to the sum of the adhesion force between the second glue dot and the second welding strip and the adhesion force between the second glue dot and the second surface of the solar cell. And the adhesion force between the glue dot and the cell surface is greater than the adhesion force between the glue dot and the welding strip. Therefore, the welding method of this application can greatly improve the tensile force between the second surface of the solar cell and the second welding strip.

[0091] Moreover, the second glue dot is arranged to completely wrap the second welding strip radially, which can also increase the contact area between the second glue dot and the second welding strip, thereby improving the adhesion force between the second glue dot and the second welding strip to further improve the tensile force between the second welding strip and the solar cell.

[0092] In step S4, when heat-treating the solar cell, the suction force of the platform and the pressure of the welding strip positioning device on the second surface (light-receiving surface) make the welding strips (including the first welding strip and the second welding strip) closely fit with the sub-grid lines on the two surfaces of the solar cell, and a temperature 5 - 30 °C higher than the melting point of the welding strip is applied for 10 - 40 s to form an alloy between the welding strip and the sub-grid line.

[0093] After the welding of the cell and the welding strip is completed, the cells are typeset, laminated and encapsulated, and then the lamination is completed. Among them, the lamination temperature is 100 °C - 150 °C, which is lower than the melting point of the welding strip, so the lamination will not cause further alloying between the welding strip and the sub-grid line.

[0094] In this embodiment, the printing of the first glue dot on the first surface is carried out first, then the arrangement and placement of the first welding strip are carried out, and then the solar cell printed with the first glue dot is pasted and placed on the first welding strip. In other embodiments, the arrangement and placement of the first welding strip can also be carried out first, then the printing of the first glue dot on the first surface is carried out, and then the solar cell printed with the first glue dot is pasted and placed on the first welding strip; or the printing of the first glue dot on the first surface and the arrangement and placement of the first welding strip are carried out simultaneously, and then the solar cell printed with the first glue dot is pasted and placed on the first welding strip.

[0095] The welding method of the solar cell of the present invention forms a first glue dot on the first surface of the solar cell by using a printing process. Since the platform for carrying the solar cell has a large air adsorption capacity, it can make the solar cell better fit with the first solder strip, so that the first solder strip has a better bonding force with the first glue dot. And a second glue dot is formed on the second surface with a smaller tensile force by using a dispensing process, so that the second glue dot wraps the second solder strip and also fits the second surface of the solar cell, which can better improve the tensile strength of the second surface of the solar cell, reduce the risk of the solder strip falling off on the second surface of the solar cell, and improve the reliability of the solar cell.

[0096] Reference Figure 3 As shown, another embodiment of the present invention further provides a welding system, which includes a glue scraping unit 10, a flipping unit 20, a transporting unit 30 and a dispensing unit 40. Among them, the dispensing unit 40 includes a welding positioning device 41 for pressing the second solder strip against the second surface of the solar cell, and a dispensing device 42 for forming a second glue dot on the second surface of the solar cell.

[0097] In this embodiment, the glue scraping unit 10 includes a platform 11 with suction force and capable of transporting solar cells. Multiple solar cells A can be placed on the platform 11. A carrier plate 12 is arranged above the platform 11, and through holes are formed in the carrier plate 12 in an array distribution. A squeegee 13 capable of moving relative to the carrier plate 12 in the transporting direction of the platform 11 is arranged above the carrier plate 12, and the glue on the carrier plate 12 is printed onto the solar cells below the carrier plate 12 by the movement of the squeegee 13.

[0098] In this embodiment, the flipping unit 20 is arranged at the end of the platform 11 in the transporting direction. The flipping unit 20 includes a rotating shaft 21 in Xi'an. A plurality of receiving platforms 22 are circumferentially arranged on the rotating shaft 21. Each receiving platform 22 can be rotated to be flush with the platform 11 to receive the solar cell A transported by the platform 11. At this time, the solar cell A is placed with its first surface facing up. The flipping unit 20 can flip the solar cell A by rotating, so that the second surface of the solar cell A faces up. Of course, in other embodiments, the flipping unit 20 can also include other structures as long as its function is to flip the solar cell with its first surface facing up to have its second surface facing up.

[0099] In this embodiment, the transporting unit 30 is preferably a manipulator. The manipulator sucks the solar cell A on the flipping unit 20 and moves it to the dispensing unit 40. The manipulator can be a multi-axis manipulator in the prior art. Since it is not the focus of the present invention, the present invention does not elaborate on it in detail here.

[0100] In this embodiment, the dispensing unit 40 includes a carrier table 43 that has suction force and can also transfer solar cells. When the solar cell A is transferred onto the carrier table 43, the welding positioning device 41 is placed on the solar cell A to position the second solder tape and the second surface of the solar cell. The dispensing device 42 is arranged on the carrier table 43. When the solar cell A is transferred below the dispensing device 42, the dispensing device 42 dispenses glue on it.

[0101] Refer to Figure 4 As shown, the welding positioning device 41 includes a fixed frame 411 and a pressing pin 412 installed on the fixed frame 411. The fixed frame 411 includes two relatively arranged fixed beams 4111, multiple cross beams 4112 installed between the two fixed beams 4111, and multiple vertical beams 4113 perpendicular to the cross beams 4112. The multiple cross beams 4112 and the multiple vertical beams 4113 form a network structure. The pressing pins 412 are located at each intersection of the cross beams 4112 and the vertical beams 4113. Among them, a dispensing port 4114 that penetrates in the thickness direction of the vertical beam 4113 is opened on the vertical beam 4113 between two adjacent pressing pins 412. Pressing pins 412 are arranged on both sides of each dispensing port 4114. When the pressing pins 412 act on the second solder tape, it can ensure that the second solder tape fits well with the surface of the battery cell, preventing the subsequent glue from drilling under the second solder tape.

[0102] Refer to Figure 5 As shown, the dispensing device 42 includes a support plate 421 and a pressing component 422. The support plate 421 is arranged on the carrier table 43 in a liftable manner. A number of glue storage tubes 4211 are arranged in an array on the support plate 421, and a number of glue outlet tubes 4212 are arranged in an array below the support plate 421. The glue outlet tubes 4212 are arranged in one-to-one correspondence and communication with the glue storage tubes 4211. The pressing component 422 is installed above the support plate 421. The pressing component 422 includes a pressing plate 4221, a number of pressing heads 4222 arranged in an array on the bottom surface of the pressing plate 4221, and a driving member for driving the pressing plate 4221 to move. The pressing heads 4222 are arranged in one-to-one correspondence with the glue storage tubes 4211. The pressing heads 4222 can be accommodated in the glue storage tubes 4211 and squeeze the glue in the glue storage tubes 4211. It can be understood that the glue is stored in the glue storage tubes 4211, and then the pressing heads 4222 above move downward to squeeze the glue in the glue storage tubes 4211, and finally the glue is extruded through the glue outlet tubes 4212 and finally lands on the second solder tape and the surface of the battery cell to form the second glue dots.

[0103] The welding system of the solar cell of the present invention can better improve the tensile strength of the second surface of the solar cell when applied to the above welding method, reduce the risk of the solder tape falling off on the second surface of the battery cell, and improve the reliability of the solar cell.

[0104] It can be understood that the welding method of the present application can be used to weld the first solder tape and the second solder tape only for a single solar cell, or to perform series welding on multiple solar cells.

[0105] Reference Figure 6 As shown, an embodiment of the present application further provides a series welding method for solar cells, including the following steps:

[0106] S10, set the first surface of a solar cell upward, and use a first gluing method to set a plurality of first glue dots on the first surface.

[0107] S20, press the first surface onto a plurality of first solder tapes, and make the first glue dots adhesively bond to the first solder tapes correspondingly.

[0108] S30, place a plurality of second solder tapes on the second surface of the solar cell, use a second gluing method to set a plurality of second glue dots on the second surface, and make the second glue dots adhesively bond to the second solder tapes correspondingly.

[0109] S40, press the first surface with the first glue dots of another solar cell onto the second solder tape to connect the two solar cells in series.

[0110] It should be noted that in this embodiment, the first surface of the solar cell is the backlight surface of the solar cell, and the second surface of the solar cell is the light-receiving surface of the solar cell.

[0111] Among them, in step S10, the solar cell can be a main-gridless crystalline silicon cell. It can be understood that the main-gridless crystalline silicon cell can completely have no main grid lines, and the solder tapes welded to the pads replace the main grid lines in the existing solar cells, or can retain some main grid lines. The main-gridless crystalline silicon cell can be a PERC cell, a TOPCon cell or an HJT cell.

[0112] The melting point of the solder tape required for the main-gridless crystalline silicon cell is 150°C - 200°C, and the tin layer composition on the surface of the solder tape is tin-lead, tin-lead-bismuth, tin-bismuth-silver, etc. The specific composition and melting point can be selected according to the type of crystalline silicon cell used.

[0113] Set the first surface of the solar cell upward, and use a printing process to set a plurality of first glue dots on the first surface. Exemplarily, the first glue dots can be printed on the first surface of the solar cell through components such as a squeegee and a carrier plate with through holes.

[0114] In step S20, a plurality of first solder tapes are arranged side by side on a platform with suction. After forming a plurality of first glue dots on the first surface of the solar cell by a printing process, the solar cell is flipped so that its first surface faces the platform and is placed on the plurality of first solder tapes placed in advance, and is adhered to the first solder tape under the suction of the platform. Among them, on the first surface of the solar cell, the number of first glue dots corresponding to a single first solder tape is preferably 2 - 50.

[0115] In step S30, the cut second solder tape is placed at a specified position on the second surface of the solar cell, and a plurality of second glue dots are set on the second surface by a dotting process. Among them, before the step of setting a plurality of second glue dots on the second surface by the dotting process, it is also necessary to apply multi-point pressure to each second solder tape to position it on the second surface of the solar cell, and the pressure magnitude of each pressure application point does not exceed 2.0 N.

[0116] In step S40, a plurality of first glue dots are formed on the first surface of another solar cell by the same first glue application method - printing process, and the first surface with the first glue dots is pressed onto the second solder tape that has been adhesively bonded to the second surface of the previous solar cell to connect the two solar cells in series.

[0117] It can be understood that forming a plurality of first glue dots on the first surface of another solar cell can be carried out simultaneously with step S10, or can be carried out separately after completing step S30, or can be carried out during the period from step S10 to step S30. The embodiments of the present application do not limit this.

[0118] The following describes the specific process of string soldering of solar cells to facilitate understanding of the technical solutions of the embodiments of the present application.

[0119] Reference Figure 7 As shown, first, a solar cell (refer to S100) having a first surface and a second surface arranged opposite to each other is provided.

[0120] Subsequently, a plurality of first glue dots (refer to S200) are formed on the first surface of the solar cell by a printing process (or glue printing process).

[0121] Then, a first solder tape is provided, and a plurality of first solder tapes are arranged side by side. After the first surface of the solar cell is flipped, it is pressed onto the plurality of first solder tapes, and the first solder tape is adhesively bonded to the first glue dots (refer to S300).

[0122] Then, place multiple cut second solder tapes on the second surface of the solar cell, and apply pressure to fix them. Use the dispensing process (or extrusion process) to form several second glue dots on the second surface, and use the second glue dots to cover the surface of the second solder tape and bond the second solder tape to the second surface (refer to S400, S500).

[0123] Finally, provide another solar cell, and press the first surface with the first glue dots thereof against the second solder tape of the previous solar cell to connect the two solar cells in series (refer to S600, S700).

[0124] Perform heat treatment on the serially connected solar cells.

[0125] In addition, in the embodiment of the present application, after placing the cut second solder tape at the specified position on the second surface of the solar cell, the second surface and the second solder tape are directly glued by the dispensing process. However, in other embodiments, after placing the cut second solder tape at the specified position on the second surface of the solar cell, apply multi-point pressure to each second solder tape to position it on the second surface of the solar cell, and then first perform the pressing and bonding of the first surface of the latter solar cell and the second solder tape, and then perform the gluing of the second surface of the previous solar cell and the second solder tape. Even, solder tapes can be continuously placed on the second surface of the latter solar cell, and the gluing of the dispensing process can be directly performed on two solar cells at one time. By completing the dispensing and gluing of two solar cells at one time, the output at the component end is increased.

[0126] Reference Figure 8 As shown, an embodiment of the present application further provides a series soldering method for solar cells, including the following steps:

[0127] S100, set several first glue dots on the first surface of a solar cell by using a first glue application method.

[0128] S200, set several second glue dots on the second surface of the solar cell by using a second glue application method, and the second glue application method is different from the first glue application method.

[0129] Among them, the first glue application method uses a printing process, and the second glue application method uses a dispensing process. In the first glue application method, only the first surface of one solar cell is glued at a time. In the second glue application method, the second surface of one solar cell can be glued, or the second surfaces of two solar cells can be glued at the same time. During the process of the second glue application method, pressure should be applied to the surface of the second solder tape to position it on the second surface of the solar cell. The pressing tool can be the solder tape positioning device in the above embodiment.

[0130] In order to improve the adhesion between the second solder strip and the second surface of the solar cell, in the second gluing method, the glue at the second glue point covers the second solder strip laid on the second surface of the solar cell from top to bottom, so as to bond the second solder strip to the second surface of the solar cell.

[0131] The welding method of the solar cell of the present invention ensures the yield of the solar cell module end while ensuring the tensile force of the second surface of the solar cell. It can complete the glue point printing and dispensing of two or even multiple solar cells at one time, and can match the rhythm of simultaneous welding of multiple solar cells currently, ensuring the yield.

[0132] In the conventional double-sided printing method, after printing on one side of the cell, it is necessary to go through a section of the production line and then print on the other side, resulting in cracking of the cell after a long movement. The welding method of the solar cell of the present invention simultaneously performs the dispensing process on the second surface (light-receiving surface) of the cell and the limiting of the cell and the second solder strip by the solder strip positioning device, thereby reducing the process steps, reducing the movement distance of the cell, preventing the cracking of the cell itself, and reducing the loss.

[0133] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0134] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A welding method for a solar cell, characterized in that, The welding method includes the following steps: Provide a solar cell, which has a first surface and a second surface arranged opposite to each other. A plurality of first sub-grid lines are formed on the first surface, and a plurality of second sub-grid lines are formed on the second surface; Form first glue dots distributed in an array on the first surface by using a first glue application method, and fix a plurality of first solder tapes on the first surface. Each of the first solder tapes is vertically distributed with respect to the first sub-grid lines and is in contact with a column of the first glue dots; Fix a plurality of second solder tapes on the second surface, and form second glue dots distributed in an array on the second surface by using a second glue application method. Each of the second solder tapes is vertically distributed with respect to the second sub-grid lines and is in contact with a column of the second glue dots; Perform heat treatment on the solar cell to weld the first solder tape and the second solder tape to the first surface and the second surface respectively.

2. The welding method of the solar cell according to claim 1, wherein The first glue application method uses a printing process.

3. The welding method of the solar cell according to claim 1, wherein Forming first glue dots distributed in an array on the first surface by using a first glue application method includes: Provide a carrier plate on which through holes distributed in an array are formed; Fix the carrier plate above the first surface of the solar cell; Coat glue on the carrier plate, and use a squeegee to print the glue onto the first surface along a direction perpendicular to the first sub-grid lines.

4. The soldering method of the solar cell according to claim 1, wherein Each of the first glue dots is located between two adjacent first sub-grid lines. The height of each first glue dot is less than or equal to the height of the first solder tape, and the width of each first glue dot is greater than or equal to the width of the first solder tape.

5. The welding method of the solar cell according to claim 1, wherein, Fixing a plurality of first solder tapes on the first surface includes: Provide first solder tapes, and arrange a plurality of the first solder tapes side by side on a platform; Place the first surface of the solar cell facing the platform on the plurality of first solder tapes, and fit it with the first solder tapes under the action of the platform.

6. The soldering method of a solar cell according to claim 1, wherein The second glue application method uses a dispensing process.

7. The soldering method of the solar cell according to claim 1, characterized in that, Forming second glue dots distributed in an array on the second surface by using a second glue application method includes: Use a solder tape positioning device to press the second solder tape against the second surface of the solar cell. Among them, the solder tape positioning device is formed with dispensing ports distributed in an array, and each of the second solder tapes is partially exposed by a corresponding column of the dispensing ports; Use a dispensing device to form second glue dots distributed in an array on the second surface of the solar cell. Among them, the dispensing device includes a plurality of dispensing tubes distributed in an array, and each dispensing tube corresponds to a dispensing port of the solder tape positioning device.

8. The soldering method of the solar cell according to claim 1, characterized in that Each of the second glue dots is located between two adjacent second sub-grid lines. The height of each second glue dot is not less than the height of the second solder tape, the width of each second glue dot is greater than or equal to the width of the second solder tape, and each second glue dot completely covers the second solder tape in the radial direction of the second solder tape.

9. The soldering method of the solar cell according to claim 1, wherein, The heat treatment temperature is 5°C - 30°C higher than the melting points of the first solder tape and the second solder tape, and the heat treatment time is 10s - 40s.

10. A welding system for the welding method of a solar cell described in any one of claims 1 to 9, characterized in that, The welding system includes a welding positioning device and a dispensing device. The welding positioning device is used to press the second solder tape onto the second surface of the solar cell, and the dispensing device is used to form second glue dots on the second surface of the solar cell.

11. The welding system according to claim 10, characterized in that, The welding positioning device includes: A fixed frame, including two relatively arranged fixed beams, multiple cross beams installed between the two fixed beams, and multiple vertical beams installed perpendicular to the cross beams; Pressing needles, installed on the fixed frame and located at each intersection of the cross beams and the vertical beams; Wherein, through glue ports are opened on the vertical beams between two adjacent pressing needles.

12. The welding system according to claim 10, wherein The dispensing device includes: A support plate, on which a number of glue storage tubes are arranged in an array, and a number of glue outlet tubes are arranged in an array below the support plate. The glue outlet tubes are in one-to-one correspondence with and communicated with the glue storage tubes; A pressing component, installed above the support plate. The pressing component includes a pressing plate, a number of pressing heads arranged in an array on the bottom surface of the pressing plate, and a driving member for driving the pressing plate to move. The pressing heads are arranged in one-to-one correspondence with the glue storage tubes, and the pressing heads can be accommodated in the glue storage tubes to squeeze the glue in the glue storage tubes.

13. A string welding method for solar cell wafers, characterized in that, It includes the following steps: Set a solar cell with its first surface facing upward, and use a first dispensing method to set a number of first glue dots on the first surface; Press the first surface onto a number of first solder tapes, and make the first glue dots adhesively bonded to the first solder tapes correspondingly; Place a number of second solder tapes on the second surface of the solar cell, use a second dispensing method to set a number of second glue dots on the second surface, and make the second glue dots adhesively bonded to the second solder tapes correspondingly; Press the first surface with the first glue dots of another solar cell onto the second solder tape to connect the two solar cells in series.

14. The string welding method of the solar cell according to claim 13, wherein On the first surface of the solar cell, the number of the first glue dots corresponding to a single first solder tape is 2 - 50.

15. The string welding method of the solar cell according to claim 13, wherein The first surface is the backlight surface of the solar cell, and the second surface is the light-receiving surface of the solar cell.

16. The string soldering method of the solar cell according to claim 13, characterized in that, Before the step of using the second dispensing method to set a number of second glue dots on the second surface, apply multi-point pressure to each second solder tape to position it on the second surface, and the pressure at each pressure application point does not exceed 2.0 N.

17. A string soldering method for solar cell chips, characterized in that, It includes the following steps: Use a first dispensing method to set a number of first glue dots on the first surface of a solar cell; Use a second dispensing method to set a number of second glue dots on the second surface of the solar cell, and the second dispensing method is different from the first dispensing method.

18. The string welding method of the solar cell according to claim 17, characterized in that, The first dispensing method uses a printing process, and the second dispensing method uses a dispensing process.

19. The string soldering method of the solar cell according to claim 17, characterized in that, In the first dispensing method, only the first surface of one solar cell is dispensed.

20. The string soldering method of the solar cell according to claim 17, characterized in that, In the second dispensing method, at least two second surfaces of the solar cells are simultaneously dispensed.

21. The string soldering method of the solar cell according to claim 17, wherein, In the second dispensing method, the glue at the second glue dots covers the second solder tapes laid on the second surface from top to bottom to bond the second solder tapes to the second surface.

22. The string welding method of a solar cell according to claim 21, wherein, During the process of the second sizing method, pressure is applied to the surface of the second solder tape to position it on the second surface.

Images