Battery string and preparation method thereof, photovoltaic module and production equipment of battery string

Abstract

The invention relates to a battery string and a preparation method thereof, a photovoltaic module and production equipment of the battery string. According to the preparation method of the cell string, the welding strip is innovatively connected with the power supply, and the reverse voltage is applied to the solar cell through the welding strip, so that the electric treatment on the solar cell in the laser welding process is realized. By applying reverse voltage to the solar cell and cooperating with laser treatment, charge carriers can be excited, and the charge carriers can be rapidly separated under the action of a strong built-in electric field and are finally gathered and compounded at a contact interface of metal and a semiconductor to generate a large amount of heat, so that the solar cell can be used as a solar cell. According to the invention, secondary sintering can be carried out on the insufficiently sintered metal-semiconductor contact, so that the contact resistance between the metal and the semiconductor is reduced, and the resistivity distribution is more uniform, thereby improving the fill factor, improving the electrical performance of the solar cell, and effectively improving the power output of the photovoltaic module.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a battery string and a preparation method thereof, a photovoltaic module, and production equipment for a battery string. Background Art

[0002] The grid lines on solar cells can be formed by printing conductive paste and sintering. The conductive paste forms a good ohmic contact with the silicon wafer through sintering, thereby improving the open circuit voltage and fill factor of the solar cell. However, unfavorable factors such as sintering parameters, silicon wafer surface cleanliness, silver paste quality and sintering equipment will affect the sintering quality, resulting in many insufficiently sintered metal-semiconductor contacts (such as Ag-Si contacts) in the solar cell. These insufficiently sintered contacts have large contact resistance, making the resistivity distribution of the solar cell uneven, which will increase the series resistance of the solar cell and reduce the power of the component. Summary of the invention

[0003] Based on this, it is necessary to provide a battery string and a preparation method thereof, a photovoltaic module, and a battery string production device to solve the problem of insufficiently sintered metal-semiconductor contacts in solar cells.

[0004] The first aspect of the present invention is to provide a method for preparing a battery string, the scheme is as follows:

[0005] A method for preparing a battery string comprises the following steps:

[0006] Pre-fixing the welding strips on a plurality of solar cells and making conductive contact with the grid lines on the solar cells;

[0007] Connecting the soldering ribbon to a power source to apply a reverse voltage to the solar cell through the soldering ribbon;

[0008] The welding strip is welded to the gate line by laser welding.

[0009] In one embodiment, the reverse voltage ranges from 5V to 20V.

[0010] In one embodiment, the reverse voltage is applied for a time period of 3s to 30s.

[0011] In one embodiment, the grid line includes a main grid and a fine grid connected to the main grid, and the laser welding process includes performing line scanning along the main grid and / or the fine grid using a first laser beam.

[0012] In one embodiment, the wavelength of the first laser beam is 600nm~1200nm.

[0013] In one embodiment, the spot width of the first laser beam is 0.1 mm to 20 mm.

[0014] In one embodiment, the solar cell is provided with a plurality of welding points, the plurality of welding points are distributed on the grid line, and when the welding ribbon is pre-fixed on the solar cell, the welding ribbon is in conductive contact with the plurality of welding points;

[0015] The laser welding process includes using a second laser beam to perform fixed-point irradiation on the welding strip located at a plurality of the welding points.

[0016] In one embodiment, the wavelength of the second laser beam is 600nm~1200nm.

[0017] In one embodiment, the laser power of the second laser beam is 20W-120W.

[0018] In one embodiment, the irradiation time of the second laser beam at each welding point is 0.1s-3s.

[0019] In one of the embodiments, the spot area of ​​the second laser beam accounts for more than 50% of the area of ​​the welding point.

[0020] In one embodiment, the grid lines include positive grid lines and negative grid lines, and the positive grid lines and the negative grid lines are located on the same surface of the solar cell.

[0021] In one of the embodiments, the solder ribbon is pre-fixed on the solar cell by using a press screen.

[0022] In one embodiment, the grid line is obtained by coating a conductive paste on the solar cell and sintering the paste at 600° C. to 720° C.

[0023] The second aspect of the present invention is to provide a battery string, the scheme is as follows:

[0024] A battery string is obtained by the preparation method of the battery string described in any of the above embodiments, wherein the battery string comprises a plurality of the solar cells and a welding strip, wherein the welding strip connects the plurality of the solar cells in series.

[0025] The third aspect of the present invention is to provide a photovoltaic module, the scheme is as follows:

[0026] A photovoltaic component comprises a first packaging structure, a second packaging structure and the battery string, wherein the battery string is arranged between the first packaging structure and the second packaging structure.

[0027] The fourth aspect of the present invention is to provide a battery string production device, the scheme is as follows:

[0028] A battery string production device, comprising:

[0029] The base is provided with a welding station, and the welding station is used to place the solar cell and the welding strips that are in conductive contact with the grid lines on the solar cell;

[0030] a power supply device, used to be connected to the welding ribbon so as to apply a reverse voltage to the solar cell through the welding ribbon; and

[0031] The laser device is used to emit laser toward the welding station to weld the welding strip to the grid line.

[0032] In one of the embodiments, the production equipment further includes a conveying device, and the conveying device is used to convey the solar cell and the welding ribbon through the welding station.

[0033] In one embodiment, the production equipment further comprises:

[0034] A fixing device is used to fix the welding ribbon on the solar cell.

[0035] Compared with the traditional solution, the above-mentioned battery string and preparation method thereof, photovoltaic module, and battery string production equipment have the following beneficial effects:

[0036] The preparation method and production equipment of the above-mentioned battery string innovatively connect the welding ribbon to the power supply to apply reverse voltage to the solar cell through the welding ribbon, thereby realizing electrical treatment of the solar cell during the laser welding process. By applying reverse voltage to the solar cell and cooperating with laser treatment, charge carriers can be excited. These carriers will be quickly separated under the action of the strong built-in electric field, and finally gather and recombine at the contact interface of the metal and the semiconductor, generating a large amount of heat, which can perform secondary sintering on the metal-semiconductor contact that is not fully sintered, so that the contact resistance between the metal and the semiconductor is reduced, thereby improving the fill factor, improving the electrical performance of the solar cell, and effectively increasing the power output of the photovoltaic module.

[0037] The photovoltaic assembly described above has a battery string according to any of the above embodiments, and can achieve corresponding beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of a process for preparing a battery string according to an embodiment;

[0039] Figure 2 A schematic diagram of applying reverse voltage to a solar cell through a welding ribbon;

[0040] Figure 3 A schematic diagram of pre-fixing a welding strip by pressing a mesh in one embodiment;

[0041] Figure 4A schematic diagram of pre-fixing a welding strip by pressing a mesh in another embodiment;

[0042] Figure 5 is a schematic diagram of a scanning path of a first laser beam line in one embodiment;

[0043] Figure 6 is a schematic structural diagram of a photovoltaic module according to an embodiment;

[0044] Figure 7 A schematic structural diagram of a battery string production device according to an embodiment;

[0045] Figure 8 It is a schematic diagram of the electrical connection between the power-on device and the welding strip.

[0046] Description of reference numerals:

[0047] 100, welding ribbon; 200, solar cell; 210, grid line; 211, main grid; 212, fine grid; 220, welding point; 230, insulating glue; 300, power supply; 400, pressing mesh; 410, pressing mesh body; 420, groove; 430, hemispherical protrusion; 20, photovoltaic module; 21, first packaging structure; 211, packaging panel; 212, first packaging film; 22, second packaging structure; 221, packaging backplane; 222, second packaging film; 23, battery string; 30, battery string production equipment; 31, machine base; 311, welding station; 32, power-on device; 321, electrical contact mechanism; 3212, conductive contact; 33, laser device; 34, conveying device; 341, conveyor belt; 342, driving motor; 35, fixing device; 351, pressing mesh. DETAILED DESCRIPTION

[0048] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0049] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0050] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number or order of the indicated technical features.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0052] Please combine Figure 1 and Figure 2 As shown, a method for preparing a battery string according to an embodiment of the present invention comprises the following steps:

[0053] Step S110 , pre-fixing the soldering ribbon 100 on the plurality of solar cells 200 , and making conductive contact with the grid lines 210 on the solar cells 200 .

[0054] Step S120 , connecting the soldering ribbon 100 to the power source 300 , so as to apply a reverse voltage to the solar cell 200 through the soldering ribbon 100 .

[0055] Step S130 , welding the welding ribbon 100 and the gate line 210 by laser welding.

[0056] The preparation method of the above-mentioned battery string connects the welding ribbon 100 to the power supply 300 to apply a reverse voltage to the solar cell 200 through the welding ribbon 100, thereby realizing electrical treatment of the solar cell 200 during the laser welding process. By applying a reverse voltage to the solar cell 200 and cooperating with the laser treatment, charge carriers can be excited, and these carriers will be quickly separated under the action of a strong built-in electric field, and finally gather and recombine at the contact interface of the metal and the semiconductor, generating a large amount of heat, and can perform secondary sintering on the insufficiently sintered metal-semiconductor contacts (such as Ag-Si contacts), so that the contact resistance between the metal and the semiconductor is reduced, thereby improving the fill factor, improving the electrical performance of the solar cell, and effectively improving the power output of the photovoltaic module.

[0057] The inventor unexpectedly discovered that due to the heat concentration effect of the infrared lamp, the temperature in the middle of the infrared lamp will be higher than the temperature at both ends no matter how the infrared lamp is adjusted, resulting in uneven heating. Therefore, the welding quality of each welding point 220 cannot be accurately controlled, affecting the yield and reliability of the assembly. The above-mentioned preparation method of the battery string adopts the laser welding method, which can avoid the above-mentioned problems. The use of laser welding can accurately control the welding quality of each welding point 220, thereby improving the yield and reliability of the assembly.

[0058] Furthermore, the laser equipment used in the above preparation method can not only perform laser welding of the welding strip 100, but also generate laser to cooperate with the applied reverse voltage to effectively excite charge carriers. There is no need to add expensive welding equipment, so the cost is low and the production efficiency is high.

[0059] The preparation method of the above-mentioned cell string can be applied to all solar cells that require electrode sintering, such as but not limited to PERC cells (passivated emitter back contact cells), TOPCon cells (tunneling oxide passivation contact cells), HJT cells (heterojunction cells), cells with gate lines all located on the back, etc.

[0060] In some examples, in step S110 , the gate lines 210 include positive gate lines and negative gate lines.

[0061] like Figure 2 As shown, in some of the examples, in step S110, the positive grid lines and the negative grid lines are both located on the same surface of the solar cell 200. Further, the positive grid lines and the negative grid lines are both located on the back side of the solar cell 200, while the front side is not blocked by the grid lines 210, and has more effective light absorption area, which maximizes the use of incident light and reduces optical losses, thereby being able to obtain high conversion efficiency.

[0062] The positive and negative grid lines each include a main grid 211 and a fine grid 212 connected to the main grid 211. The main grids 211 of the positive grid lines and the main grids 211 of the negative grid lines are alternately arranged, and the fine grids 212 of the positive grid lines and the fine grids 212 of the negative grid lines are distributed in an interdigitated manner.

[0063] In some of the examples, in step S110, a plurality of welding points 220 are provided on the solar cell 200, and the plurality of welding points 220 are distributed on the grid lines 210, more specifically, on the positive electrode main grid 211 and the negative electrode main grid 211. When the welding ribbon 100 is pre-fixed on the solar cell 200, the welding ribbon 100 is in conductive contact with the plurality of welding points 220.

[0064] In some of the examples, in step S110 , a press screen 400 is used to pre-fix the solder ribbon 100 on the solar cell 200 .

[0065] like Figure 3 As shown, the pressing mesh 400 includes a pressing mesh body 410 , on which grooves 420 are distributed, and a hemispherical protrusion 430 is arranged in the groove 420 . The hemispherical protrusion 430 is used to press the welding ribbon 100 so that the welding ribbon 100 contacts the welding point 220 .

[0066] For solar cells 200 with both positive and negative grid lines located at the back, insulating glue 230 is provided at the grid lines 210 to prevent the positive and negative grid lines from being connected during welding of the welding ribbon 100 and causing a short circuit. Since the insulating glue 230 has a certain height, the welding ribbon 100 cannot directly contact the welding point 220 in the horizontal direction. Therefore, for such solar cells, Figure 4 As shown, the pressing mesh 400 used includes a pressing mesh body 410 and a hemispherical protrusion 430 arranged on the pressing mesh body 410. The hemispherical protrusion 430 protrudes from the surface of the pressing mesh body 410, so that the hemispherical protrusion 430 can better press the welding strip 100, so that the welding strip 100 can have good contact with the welding point 220.

[0067] The gate line 210 is obtained by coating a conductive paste on the solar cell 200 and performing a sintering process.

[0068] In some of the examples, the temperature of the sintering process is 600° C. to 720° C. Further, in some of the examples, the temperature of the sintering process is 690° C. to 710° C. Further, in some of the examples, the temperature of the sintering process is 700° C. In some specific examples, the temperature of the sintering process is, for example, 600° C., 620° C., 640° C., 660° C., 680° C., 700° C., 720° C., etc., or a range between any two of the above values.

[0069] In conventional technology, the normal sintering temperature of the conductive paste is higher than 720°C. Unlike the normal sintering temperature, the sintering process is performed at a lower temperature. At this time, the gate line 210 is in an insufficiently sintered state, but the corrosion degree of the passivation film can be reduced, which is beneficial to improving the open circuit voltage of the solar cell.

[0070] In some examples, in step S120, the reverse voltage ranges from 5 V to 20 V. Further, in some examples, the reverse voltage ranges from 8 V to 15 V. In some specific examples, the reverse voltage ranges from 5 V, 6 V, 7 V, 8 V, 9 V, 10 V, 11 V, 12 V, 13 V, 14 V, 15 V, 16 V, 17 V, 18 V, 19 V, 20 V, etc., or a range between any two of the above values.

[0071] In some of the examples, the reverse voltage is applied for a time of 3s to 30s. Further, in some of the examples, the reverse voltage is applied for a time of 6s to 25s. In some specific examples, the reverse voltage is applied for a time of, for example, 3s, 5s, 7s, 9s, 11s, 13s, 15s, 17s, 19s, 21s, 23s, 25s, 27s, 29s, 30s, etc., or a range between any two of the above values.

[0072] In some examples, in step S130, the laser welding process includes using a first laser beam to perform line scanning along the main grid 211 and / or the fine grid 212. For example, the first laser beam performs line scanning along the main grid 211. For another example, the first laser beam performs line scanning along the fine grid 212. For another example, the first laser beam performs line scanning along the main grid 211 and the fine grid 212.

[0073] like Figure 5 As shown, in some examples, the soldering ribbon 100 covers the main grid 211. When the first laser beam performs line scanning along the main grid 211, it also performs line scanning along the soldering ribbon 100 at the same time. Figure 5 The middle arrow shows the path of the first laser beam line scan.

[0074] By using a laser to perform line scanning on the solar cell 200 along the main grid 211 and / or the fine grid 212, charge carriers can be excited. At the same time, since a reverse voltage is applied to the cell, these carriers will be quickly separated under the action of a strong built-in electric field, and finally gather and recombine at the Ag-Si contact interface to generate a large amount of heat, effectively promoting the mutual diffusion of Ag and Si, realizing secondary sintering of the Ag-Si contact, and significantly reducing the contact resistance between the metal and the semiconductor.

[0075] In some of the examples, the wavelength of the first laser beam is 600 nm to 1200 nm. Further, in some of the examples, the wavelength of the first laser beam is 700 nm to 1200 nm. In some specific examples, the wavelength of the first laser beam is, for example, 1064 nm, 904 nm, or 808 nm.

[0076] In some examples, the laser power of the first laser beam is 1 W to 60 W. Further, in some examples, the laser power of the first laser beam is 10 W to 50 W. In some specific examples, the laser power of the first laser beam is, for example, 1 W, 5 W, 10 W, 15 W, 20 W, 25 W, 30 W, 35 W, 40 W, 45 W, 50 W, 55 W, 60 W, etc., or a range between any two of the above values.

[0077] In some of the examples, the scanning speed of the first laser beam is 1m / s to 60m / s. Further, in some of the examples, the scanning speed of the first laser beam is 10m / s to 50m / s. In some specific examples, the scanning speed of the first laser beam is, for example, 1m / s, 5m / s, 10m / s, 15m / s, 20m / s, 25m / s, 30m / s, 35m / s, 40m / s, 45m / s, 50m / s, 55m / s, 60m / s, etc., or a range between any two of the above values.

[0078] In some of the examples, the spot width of the first laser beam is 0.1 mm to 20 mm. The spot width is the size of the spot of the first laser beam perpendicular to the scanning path of the first laser beam. Further, in some of the examples, the spot width of the first laser beam is 1 mm to 15 mm. In some specific examples, the spot width of the first laser beam is, for example, 0.1 mm, 0.5 mm, 1 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, etc., or a range between any two of the above values.

[0079] In some of the examples, in step S130 , the laser welding process includes using a second laser beam to perform targeted irradiation on the welding ribbon 100 located at a plurality of welding points 220 .

[0080] By performing fixed-point irradiation on the soldering ribbon 100 located at a plurality of soldering points 220 , metallization interconnection between the soldering ribbon 100 and the soldering points 220 is achieved.

[0081] In some of the examples, the wavelength of the second laser beam is 600nm-1200nm. Further, in some of the examples, the wavelength of the second laser beam is 700nm-1000nm. In some specific examples, the wavelength of the second laser beam is, for example, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm, 1050nm, 1100nm, etc.

[0082] In some examples, the laser power of the second laser beam is 20 W to 120 W. Further, in some examples, the laser power of the second laser beam is 50 W to 100 W. In some specific examples, the laser power of the second laser beam is, for example, 20 W, 3 W, 40 W, 50 W, 60 W, 70 W, 80 W, 90 W, 100 W, 110 W, 120 W, etc., or a range between any two of the above values.

[0083] In some examples, the irradiation time of the second laser beam at each welding point 220 is 0.1s-3s. Further, in some examples, the irradiation time of the second laser beam at each welding point 220 is 0.5s-2s. In some specific examples, the irradiation time of the second laser beam at each welding point 220 is, for example, 0.1s, 0.3s, 0.5s, 0.8s, 1s, 1.3s, 1.5s, 1.8s, 2s, 2.3s, 2.5s, 2.8s, 3s, etc., or a range between any two of the above values.

[0084] In some of these examples, the spot area of ​​the second laser beam accounts for more than 50% of the area of ​​the welding point 220, for example, 50% to 100%. Further, in some of these examples, the spot area of ​​the second laser beam accounts for 70% to 100% of the area of ​​the welding point 220. In some specific examples, the spot area of ​​the second laser beam accounts for, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% of the area of ​​the welding point 220, or a range between any two of the above values.

[0085] When the first laser beam and the second laser beam are used for processing, the processing of the first laser beam and the second laser beam can be performed simultaneously, or the processing of the first laser beam can be performed first and then the processing of the second laser beam, or the processing of the second laser beam can be performed first and then the processing of the first laser beam.

[0086] The preparation method of the above-mentioned battery string connects the welding ribbon 100 to the power supply 300 to apply a reverse voltage to the solar cell 200 through the welding ribbon 100, thereby realizing electrical treatment of the solar cell 200 during the laser welding process. By applying a reverse voltage to the solar cell 200 and cooperating with the laser treatment, charge carriers can be excited, and these carriers will be quickly separated under the action of a strong built-in electric field, and finally gather and recombine at the contact interface of the metal and the semiconductor, generating a large amount of heat, and can perform secondary sintering on the insufficiently sintered metal-semiconductor contacts (such as Ag-Si contacts), so that the contact resistance between the metal and the semiconductor is reduced, thereby improving the fill factor, improving the electrical performance of the solar cell, and effectively improving the power output of the photovoltaic module.

[0087] Due to the heat concentration effect of the infrared lamp, the temperature in the middle of the infrared lamp will be higher than that at both ends, and the heating is uneven, so the welding quality of each welding point 220 cannot be accurately controlled, which affects the yield and reliability of the assembly. The above-mentioned preparation method of the battery string adopts the laser welding method, which can avoid the above-mentioned problems. The laser welding can accurately control the welding quality of each welding point 220, thereby improving the yield and reliability of the assembly.

[0088] Furthermore, the laser equipment used in the above preparation method can not only perform laser welding of the welding strip 100, but also generate laser light in combination with the applied reverse voltage to effectively excite charge carriers. No additional expensive welding equipment is required, the cost is low, and the production efficiency is high.

[0089] The preparation method of the above-mentioned cell string can be applied to all solar cells that require electrode sintering, such as but not limited to PERC cells (passivated emitter back contact cells), TOPCon cells (tunneling oxide passivation contact cells), HJT cells (heterojunction cells), cells with gate lines all located on the back, etc.

[0090] Furthermore, the present invention also provides a battery string.

[0091] A battery string of an embodiment is obtained by any of the above-mentioned preparation methods. The battery string includes a plurality of solar cells and a welding strip connecting the plurality of solar cells in series.

[0092] Furthermore, the present invention also provides a photovoltaic module.

[0093] like Figure 6 As shown, a photovoltaic assembly 20 of an embodiment includes a first packaging structure 21, a second packaging structure 22 and the above-mentioned battery string 23. The battery string 23 is arranged between the first packaging structure 21 and the second packaging structure 22.

[0094] In some examples, the first packaging structure 21 includes a packaging panel 211 and a first packaging film 212 disposed between the packaging panel 211 and the battery string 23 .

[0095] Exemplarily, the material of the packaging panel 211 is, for example but not limited to, glass, organic polymer, etc.

[0096] For example, the first packaging film 212 may be, but is not limited to, one or more of EVA, POE, TPO, TPU, and PVB. The first packaging film 212 may be a single layer or a multi-layer stack.

[0097] In some examples, the second packaging structure 22 includes a packaging back plate 221 and a second packaging adhesive film 222 disposed between the packaging back plate 221 and the battery string 23 .

[0098] Exemplarily, the material of the packaging back plate 221 is, for example, but not limited to, glass, organic polymer, etc.

[0099] For example, the second packaging film 222 may be, but is not limited to, one or more of EVA, POE, TPO, TPU, and PVB. The second packaging film 222 may be a single layer or a multi-layer stack.

[0100] Furthermore, the present invention also provides a battery string production device, which can be applied to the above-mentioned battery string preparation method.

[0101] like Figure 7As shown, a battery string production device 30 according to an embodiment includes a machine base 31 , a power supply device 32 , and a laser device 33 .

[0102] The base 31 is provided with a welding station 311, and the welding station 311 is used to place the solar cell and the welding strip that is in conductive contact with the grid line on the solar cell.

[0103] The power supply device 32 is used to be connected to the soldering ribbon so as to apply a reverse voltage to the solar cell through the soldering ribbon.

[0104] The laser device 33 is used to emit laser toward the welding station 311 to weld the welding strip to the grid line.

[0105] In some of the examples, the laser device 33 can generate a first laser beam that performs line scanning along the main grid and / or fine grid on the solar cell. In some of the examples, the laser device 33 can generate a second laser beam that performs point irradiation on the welding strip located at multiple welding points.

[0106] A beam splitter or a beam splitter may be provided in the laser device 33 to split the laser beam into a plurality of smaller beams, so that welding at a plurality of welding points can be performed simultaneously to improve efficiency. In addition, a plurality of welding stations 311 and a plurality of laser devices 33 may also be provided to weld a plurality of strings of solar cells simultaneously.

[0107] The parameters of the first laser beam and the second laser beam are specifically as described above.

[0108] like Figure 8 As shown, the power-on device 32 includes an electric contact mechanism 321 and a first lifting component (not shown in the figure) connected to the electric contact mechanism 321, and the first lifting component is used to drive the electric contact mechanism 321 to descend so that the conductive contact 3212 on the electric contact mechanism 321 contacts the soldering strip 100, or to drive the electric contact mechanism 321 to rise so that the conductive contact 3212 is separated from the soldering strip 100.

[0109] like Figure 7 As shown, in some examples, the production equipment 30 further includes a conveyor 34, which is used to convey the solar cells and the solder ribbons through the welding station 311. The conveyor 34 includes, for example, a conveyor belt 341 and a drive motor 342 for driving the conveyor belt 341.

[0110] like Figure 7 As shown, in some examples, the production equipment 30 further includes a fixing device 35. The fixing device 35 is used to fix the solder ribbon on the solar cell.

[0111] like Figure 7 As shown, in some examples, the fixing device 35 includes a pressing net 351. The structure of the pressing net 351 is specifically as described above.

[0112] Furthermore, the fixing device 35 also includes a second lifting component (not shown in the figure) connected to the pressing mesh 351, and the second lifting component is used to drive the pressing mesh 351 to descend to press the welding strip, or drive the pressing mesh 351 to rise.

[0113] In some examples, the production equipment 30 also includes a detection device (not shown in the figure). The detection device is used to detect the position of the solar cell on the base 31 to determine whether the solar cell is offset. If no offset is detected, the fixing device 35 is used to press the soldering ribbon to prevent the solar cell and the soldering ribbon from being displaced. If an offset is detected, the operation of the equipment can be suspended to adjust the position of the solar cell.

[0114] In some of the examples, the detection device includes a contour detector (not shown in the figure). Further, the contour detector is an ultra-high-speed contour detector.

[0115] The production equipment 30 of the above-mentioned battery string is provided with a power-on device 32 and a laser device 33. The power-on device 32 is used to apply a reverse voltage to the solar cell through the welding strip, so as to realize electrical treatment of the solar cell during the laser welding process. The laser device 33 is used to weld the welding strip to the grid line. By applying a reverse voltage to the solar cell and cooperating with the laser treatment, the charge carriers can be excited. These carriers will be quickly separated under the action of the strong built-in electric field, and finally gather and recombine at the contact interface between the metal and the semiconductor, generating a large amount of heat, and can perform secondary sintering on the metal-semiconductor contacts (such as Ag-Si contacts) that are not fully sintered, so as to reduce the contact resistance between the metal and the semiconductor, thereby improving the fill factor, improving the electrical performance of the solar cell, and effectively improving the power output of the photovoltaic module.

[0116] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a battery string, characterized in that: The following steps are involved: Pre-fixing the welding strips on a plurality of solar cells and making conductive contact with the grid lines on the solar cells; Connecting the soldering ribbon to a power source to apply a reverse voltage to the solar cell through the soldering ribbon; The welding strip is welded to the gate line by laser welding.

2. The preparation method according to claim 1, characterized in that The grid line includes a main grid and a fine grid connected to the main grid, and the laser welding process includes using a first laser beam to perform line scanning along the main grid and / or the fine grid.

3. The preparation method according to claim 2, characterized in that: The preparation method meets at least one of the following characteristics (1) to (4): (1) The wavelength of the first laser beam is 600nm~1200nm; (2) The laser power of the first laser beam is 1W~60W; (3) The scanning speed of the first laser beam is 1m / s~60m / s; (4) The spot width of the first laser beam is 0.1 mm to 20 mm.

4. The preparation method according to any one of claims 1 to 3, characterized in that The solar cell is provided with a plurality of welding points, the plurality of welding points are distributed on the grid line, and when the welding strip is pre-fixed on the solar cell, the welding strip is in conductive contact with the plurality of welding points; The laser welding process includes using a second laser beam to perform fixed-point irradiation on the welding strip located at a plurality of the welding points.

5. The preparation method according to claim 4, characterized in that: The preparation method meets at least one of the following characteristics (1) to (4): (1) The wavelength of the second laser beam is 600nm~1200nm; (2) The laser power of the second laser beam is 20W~120W; (3) The irradiation time of the second laser beam at each welding point is 0.1s to 3s; (4) The spot area of ​​the second laser beam accounts for more than 50% of the area of ​​the welding point.

6. The preparation method according to any one of claims 1 to 3 and 5, characterized in that: The grid lines include positive grid lines and negative grid lines, and the positive grid lines and the negative grid lines are both located on the same surface of the solar cell.

7. The preparation method according to any one of claims 1 to 3 and 5, characterized in that: The soldering ribbon is pre-fixed on the solar cell by using a pressing net.

8. The preparation method according to any one of claims 1 to 3 and 5, characterized in that: The grid line is obtained by coating the solar cell with a conductive paste and performing a sintering treatment at 600° C. to 720° C.

9. A battery string, characterized in that: The battery string is obtained by the preparation method of any one of claims 1 to 8, wherein the battery string comprises a plurality of the solar cells and a welding strip, and the welding strip connects the plurality of the solar cells in series.

10. A photovoltaic module, characterized in that: The invention comprises a first packaging structure, a second packaging structure and the battery string as claimed in claim 9, wherein the battery string is arranged between the first packaging structure and the second packaging structure.

11. A battery string production device, characterized in that: include: The base is provided with a welding station, and the welding station is used to place the solar cell and the welding strips that are in conductive contact with the grid lines on the solar cell; A power supply device, used to be connected to the welding ribbon so as to apply a reverse voltage to the solar cell through the welding ribbon; as well as A laser device is used to emit laser toward the welding station to weld the welding strip to the grid line.

12. The production equipment according to claim 11, characterized in that The production equipment also includes a conveying device, which is used to convey the solar cell and the welding ribbon through the welding station.

13. The production equipment according to claim 11 or 12, characterized in that: The production equipment also includes: A fixing device is used to fix the welding ribbon on the solar cell.

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