Photovoltaic cell welding device and welding method

Abstract

The present application provides a welding device and a welding method for a photovoltaic cell. The welding device has a plurality of strip air outlets. The welding strip of the photovoltaic cell extends along a first direction and covers a plurality of electrode welding points arranged along the first direction on the cell. During welding, the strip air outlet of the welding device is perpendicular to the welding strip, and the plurality of strip air outlets are arranged along the first direction, and the plurality of strip air outlets respectively correspond to the plurality of electrode welding points arranged along the first direction on the cell. The electrode welding points on the same welding strip correspond to different strip air outlets, and the strip air outlets are distributed at intervals. The welding hot air output by the strip air outlet welds the welding strip covering the electrode welding points in the area corresponding to the electrode welding points, and the welding strip between the electrode welding points is less heated. The overall expansion of the welding strip when heated is less than that of the prior art, and the shrinkage of the welding strip after cooling is also relatively small, thereby reducing the warping of the cell.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic cells, and in particular, to a welding device and a welding method for photovoltaic cells. Background Art

[0002] In solar photovoltaic technology, the most notable feature of IBC solar cells is that the PN junction and metal contact are both on the back of the cell. The front of the cell completely avoids the shading of the metal grid electrode, which can maximize the use of incident light, reduce optical losses, and have a higher short-circuit current.

[0003] However, the positive and negative electrodes and series welding strips of IBC cells are arranged on the back, which can easily cause the cell to warp after welding. This will cause the cell to break, split, or have hidden cracks during the subsequent lamination process, thus affecting product quality.

[0004] Therefore, how to reduce the warping of the battery cell is a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art, and proposes a photovoltaic cell welding device and welding method. The welding device has a plurality of strip-shaped air outlets, and the plurality of strip-shaped air outlets heat the plurality of electrode welding points of the cell sheet covered by the welding strip respectively, thereby reducing the heating of the welding strip between the electrode welding points, and further reducing the warping of the cell sheet when the welding strip cools and shrinks.

[0006] In order to achieve the purpose of the present application, a photovoltaic cell welding device is provided, comprising a plurality of strip air outlets for outputting welding hot air, wherein the plurality of strip air outlets are arranged in a first direction to respectively correspond to a plurality of electrode welding points of a cell sheet covered by a welding strip extending along the first direction, and a length direction of each of the strip air outlets is perpendicular to the first direction to weld a plurality of welding strips arranged in a direction perpendicular to the first direction.

[0007] In some embodiments, the welding device is a concentrated hot air heater.

[0008] In some embodiments, the width of the strip-shaped air outlet is greater than or equal to 2 mm and less than or equal to 4 mm.

[0009] In some embodiments, the length of the strip-shaped air outlet is greater than or equal to the distance between two welding strips near the edge of the battery cell.

[0010] In some embodiments, a press is further included, and the press is used to press the welding ribbon to the battery cell when welding the welding ribbon and the electrode welding point.

[0011] In some embodiments, the presser is an elastic presser.

[0012] In some embodiments, the photovoltaic cell includes n cells, and the number of rows of the matrix of the electrode welding points on each cell is the same, wherein n is a positive integer greater than or equal to 3;

[0013] The welding strip includes a first welding strip, a second welding strip and a third welding strip, the first welding strip is used to connect the 2a+1th battery cell and the 2a+2th battery cell from one end of the photovoltaic cell, the second welding strip is used to connect the 2a+2th battery cell and the 2a+3th battery cell, and the third welding strip is arranged on the 1st battery cell and the nth battery cell, and is used to connect the rows of the matrix of the remaining electrode welding points, wherein a is an integer greater than or equal to 0;

[0014] The first welding strips and the second welding strips are alternately distributed along the column direction of the matrix of the electrode welding points.

[0015] The present application also provides a photovoltaic cell welding method, comprising:

[0016] Make the first surface of the battery sheet face the direction of the strip air outlet, and move the battery sheet along the first direction to below the strip air outlet, so that each row of electrode welding points perpendicular to the first direction corresponds to each strip air outlet;

[0017] Each of the strip-shaped air outlets outputs welding hot air to weld a plurality of welding strips arranged in a vertical first direction and covering electrode welding points of the battery cell in the first direction.

[0018] In some embodiments, each of the strip-shaped air outlets outputs welding hot air to weld a plurality of welding strips arranged in a vertical first direction and covering electrode welding points of the battery cell in the first direction, including:

[0019] The strip-shaped air outlets of the welding device are controlled to synchronously output welding hot air, so as to synchronously weld a plurality of welding strips arranged along a vertical first direction and covering the electrode welding points of the battery cell in the first direction.

[0020] In some embodiments, the temperature of the welding hot air from each of the strip-shaped air outlets is greater than or equal to 183° C. and less than or equal to 210° C.

[0021] This application has the following beneficial effects:

[0022] The photovoltaic cell welding device provided in the present application has a plurality of strip air outlets. The welding strip of the photovoltaic cell extends along the first direction and covers a plurality of electrode welding points arranged along the first direction on the cell. During the welding process, the strip air outlet of the welding device is perpendicular to the welding strip, and the plurality of strip air outlets are arranged along the first direction. The plurality of strip air outlets respectively correspond to the plurality of electrode welding points arranged along the first direction on the cell, so that the strip air outlet of the welding device can weld the plurality of welding strips arranged in the perpendicular first direction to the electrode welding points covered by them. The electrode welding points on the same welding strip correspond to different strip air outlets, and the strip air outlets are distributed at intervals. The welding hot air output by the strip air outlet welds the welding strip covering the electrode welding points in the area corresponding to the electrode welding points, and the welding strip between the electrode welding points is less heated. The overall expansion of the welding strip when heated is less than that of the prior art, and the shrinkage of the welding strip after cooling is also relatively small, thereby reducing the warping of the cell.

[0023] In addition, the present application also provides a welding method using the above welding device, and has the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of a photovoltaic cell string composed of solar cells;

[0025] Figure 2 for Figure 1 A schematic diagram of the distribution of electrode welding points on the first surface of the battery cell;

[0026] Figure 3 This is a front view of the cooperation between the welding device and the battery cell in a specific implementation manner of the present application;

[0027] Figure 4 for Figure 3 A side view of the welding device and the battery cell;

[0028] Figure 5 for Figure 3 A schematic diagram of the structure of the welding device and the battery cell;

[0029] Figure 6 for Figure 3 Schematic diagram of the structure of the medium pressure tool.

[0030] in, Figures 1 to 6 The reference numerals in the drawings are:

[0031] Welding box 1, welding nozzle 2, battery cell 3, electrode welding point 31, welding ribbon 4, first welding ribbon 41, second welding ribbon 42, third welding ribbon 43, elastic pressing tool 5, pressing tool body 51, pressing needle 52, avoidance hole 53. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present application, the photovoltaic cell welding device and welding method provided by the present application are described in detail below in conjunction with the accompanying drawings.

[0033] The photovoltaic cell welding device provided in the present application is used to weld the welding strip 4 and the electrode welding point 31 of the photovoltaic cell. Figure 1 and Figure 2 As shown, the photovoltaic cell includes a plurality of cells 3 and a plurality of welding strips 4. The cells 3 are arranged along a first direction. Figure 1 and Figure 2 The direction indicated by the middle arrow is the first direction. The positive and negative electrodes of the battery cell 3 are both located on the first surface. The first surface of each battery cell 3 is provided with a plurality of electrode welding points 31 corresponding to the positive electrode or the negative electrode, and the plurality of electrode welding points 31 on the first surface of each battery cell 3 are distributed in a rectangular array. The welding strip 4 extends along the first direction and covers a row of electrode welding points 31 distributed along the first direction. There are multiple rows of electrode welding points 31 distributed along the first direction on the battery cell 3, and they are distributed perpendicular to the first direction. Multiple welding strips 4 are also distributed perpendicular to the first direction, and cover each row of electrode welding points 31 distributed along the first direction one by one. The welding device welds and fixes the welding strip 4 to each electrode welding point 31 it covers. During the welding process, the welding strip 4 expands due to heat, increases in length, and is fixed to the electrode welding point 31. Subsequently, it shrinks after cooling, resulting in a shortening of the length of the welding strip 4. Although the battery cell 3 will expand when heated, since the expansion rate of the battery cell 3 is smaller than the expansion rate of the welding strip 4, the increase in the length of the welding strip 4 after heating is relatively large. At this time, the welding strip 4 is welded and fixed to the electrode welding point 31. After cooling, the shrinkage of the welding strip 4 is greater than the shrinkage of the battery cell 3, so tensile stress is generated at the electrode welding point 31, causing the battery cell 3 to warp.

[0034] like Figures 3 to 5 As shown, the welding device has a plurality of strip air outlets. During welding, the strip air outlet faces the first surface of the battery cell 3, and outputs welding hot air to heat the welding strip 4 and the electrode welding point 31 to achieve welding fixation. The plurality of strip air outlets are distributed at intervals, and the arrangement of the strip air outlets is adapted to the arrangement of the electrode welding points 31. During welding, the length direction of the strip air outlet is perpendicular to the first direction. The plurality of strip air outlets correspond one-to-one to the plurality of rows of electrode welding points 31 distributed along the first direction. Of course, the user can, as needed, set more than two strip air outlets to weld the same row of electrode welding points 31 perpendicular to the first direction, and each strip air outlet corresponds to a different electrode welding point 31 in the row, which is not limited here. It should be noted that the welding strip 4 covers the top of the electrode welding point 31, Figure 5 The electrode welding point 31 is shown to indicate the positional relationship among the welding strip 4 , the electrode welding point 31 and the strip-shaped air outlet, but it does not mean that the electrode welding point 31 is located above the welding strip 4 .

[0035] like Figure 5As shown, during the welding process, the strip air outlet of the welding device is perpendicular to the welding strip 4. The strip air outlet corresponds to the position of the electrode welding point 31, and there is no strip air outlet above the welding strip 4 between two adjacent electrode welding points 31. Therefore, during the welding process, the welding hot air mainly heats the area corresponding to the electrode welding point 31, and the portion of the welding strip 4 between the two electrode welding points 31 is less heated, and the corresponding thermal expansion is also smaller. After the welding strip 4 cools down, the portion of the welding strip 4 between the two electrode welding points 31 shrinks less, thereby reducing the warping of the battery cell 3.

[0036] In some embodiments, the welding device is a concentrated hot air heater, which has a welding box 1, in which a welding nozzle 2 is provided, and the outlet of the welding nozzle 2 is a strip-shaped outlet. During welding, the battery cell 3 moves under the welding box 1, and the strip-shaped outlet faces the battery cell 3 and delivers welding hot air to the electrode welding point 31. The structure of other parts of the concentrated hot air heater can refer to the prior art and will not be repeated here.

[0037] In some embodiments, the width of the strip air outlet is adapted to the size of the electrode welding spot 31. Usually, the electrode welding spot is rectangular, and the width of the strip air outlet is equal to or close to the length of the electrode welding spot 31. Specifically, the width of the strip air outlet is greater than or equal to 2 mm and less than or equal to 4 mm. The width of the strip air outlet is relatively small, which can reduce the diffusion of welding hot air to the area outside the electrode welding spot 31 during welding, thereby reducing the heating of the portion of the welding strip 4 between two adjacent electrode welding spots 31, and further reducing the warping of the battery cell 3. Of course, the user can also set the width of the strip air outlet as needed, which is not limited here.

[0038] In some embodiments, the length of the strip air outlet is greater than or equal to the distance between the two welding strips 4 near the edge of the battery cell 3, so that one strip air outlet can complete the welding of a row of electrode welding points 31 perpendicular to the first direction. Specifically, the length of the strip air outlet may be greater than or equal to the length of the battery cell 3 in the perpendicular first direction. In a specific embodiment of the present application, the length of the strip air outlet is 5mm to 20mm greater than the length of the battery cell 3 in the perpendicular first direction. Of course, the user can also set the length of the strip air outlet as needed, which is not limited here.

[0039] Optionally, the number of strip-shaped air outlets may be equal to the number of rows of electrode welding points 31 of two battery cells 3 distributed in the first perpendicular direction. During welding, the strip-shaped air outlets correspond one to one with the rows distributed in this manner on one battery cell 3, and each strip-shaped air outlet synchronously outputs welding hot air, completing the welding of two battery cells 3 in one welding operation. Of course, the user can also set the number of strip-shaped air outlets as needed, which is not limited here.

[0040] In this embodiment, the length of the strip air outlet of the concentrated hot air heater is greater than or equal to the length of the battery cell 3 in the first vertical direction, and the number of strip air outlets is equal to the number of rows of electrode welding points 31 of two battery cells 3 corresponding to the strip air outlets. The concentrated hot air heater can complete the welding of two battery cells 3 at a time, thereby improving the welding efficiency. In addition, the width of the strip air outlet is adapted to the size of the electrode welding point 31, reducing the heating of the welding hot air on the welding strip 4 between two adjacent electrode welding points 31, and further reducing the warping of the battery cell 3. Of course, the various sizes in this embodiment can also be used for other types of hot air heaters, which are not limited here.

[0041] In some embodiments, the welding device further comprises a press. Figure 3 and Figure 4 As shown, during the welding process, the press is arranged above the battery cell 3 to press the soldering ribbon 4 against the first surface of the battery cell 3, thereby preventing the soldering ribbon 4 from moving during the welding process and reducing the deformation of the soldering ribbon in the pressing area during the welding heating process.

[0042] Optionally, the pressing tool has a plurality of pressing needles 52. Figure 6 As shown, the press includes a press body 51 and a clamping needle 52. The clamping needle 52 is arranged on the lower surface of the press body 51 and is used to clamp the welding strip. In addition, the press body 51 is provided with a clearance hole 53 for avoiding welding hot air. The clamping needles 52 are arranged on both sides of the clearance hole 53, which can not only ensure that the welding strip 4 is clamped on the battery cell 3, but also avoid the press affecting the welding of the welding device. In addition, the clamping needles 52 can be an even number, and are respectively arranged on both sides of the electrode welding point 31. The clamping needles 52, the electrode welding point 31, and the clamping needles 52 can be distributed along the first direction. The clamping needles 52 can further reduce the diffusion of welding hot air to the part of the welding strip 4 located between the electrode welding points 31. The structure of the press can refer to the prior art and will not be repeated here.

[0043] Optionally, the pressing tool is an elastic pressing tool 5, and the elastic pressing tool 5 supports the pressing pin 52 through a supporting member such as a spring. When the welding strip 4 is pressed, the elastic member undergoes elastic deformation, and the elastic force of the elastic member can ensure that the welding strip 4 is pressed against the battery cell 3, and can also prevent the battery cell 3 from being deformed or broken due to excessive pressing force. The structure of the elastic pressing tool 5 can refer to the prior art and will not be described in detail here.

[0044] In this embodiment, the welding device also includes an elastic press 5, which presses the welding ribbon 4 against the battery cell 3 during the welding process to prevent the welding ribbon 4 from moving during the movement of the battery cell 3 and the welding process, and at the same time prevents the battery cell 3 from being deformed or broken due to excessive pressing force.

[0045] In some embodiments, the photovoltaic cell includes n cells 3, and the number of rows of the matrix of electrode welding points 31 on each cell 3 is the same, wherein n is a positive integer greater than or equal to 3; the welding strip 4 includes a first welding strip 41, a second welding strip 42 and a third welding strip 43, the first welding strip 41 is used to connect the 2a+1th cell 3 and the 2a+2th cell 3 from one end of the photovoltaic cell, the second welding strip 42 is used to connect the 2a+2th cell 3 and the 2a+3th cell 3, and the third welding strip 43 is arranged on the 1st cell 3 and the nth cell 3, and is used to connect the rows of the matrix of the remaining electrode welding points 31, wherein a is an integer greater than or equal to 0; the first welding strip 41 and the second welding strip 42 are alternately distributed along the direction of the columns of the matrix of electrode welding points 31. Figure 1 In the specific embodiment shown, the first row of electrode welds 31 distributed along the first direction on the first battery cell 3 and the second battery cell 3 are connected in series via a first welding strip 41, and the first row of electrode welds 31 distributed along the first direction on the third battery cell 3 and the fourth battery cell 3 are also connected in series via a first welding strip 41. The second row of electrode welds 31 distributed along the first direction on the second battery cell 3 and the third battery cell 3 are connected in series via a second welding strip 42. The second row of electrode welds 31 distributed along the first direction on the first battery cell 3 are connected in series via a third welding strip 43, and the second row of electrode welds 31 distributed along the first direction on the fourth battery cell 3 are connected in series via a third welding strip 43. The above distribution method is repeated for the remaining welding strips 4 to electrically connect the electrode welds 31 on the battery cells 3. In this specific embodiment, four battery cells 3 are taken as an example for description, and the number of battery cells 3, the number of electrode welds 31, and the distribution method are not limited to Figure 1 Specific implementation method.

[0046] In this embodiment, the combination of the first welding strip 41, the second welding strip 42 and the third welding strip 43 is alternately distributed along the vertical first direction to connect the various battery cells 3 in series. The first welding strip 41 and the second welding strip 42 can distribute the tension between the battery cells 3, thereby reducing the risk of damage to the photovoltaic cells.

[0047] The present application also provides a photovoltaic cell welding method, which is used for any of the above welding devices, comprising:

[0048] Make the first surface of the battery sheet face the direction of the strip air outlet, and move the battery sheet along the first direction to below the strip air outlet, so that each row of electrode welding points perpendicular to the first direction corresponds to each strip air outlet;

[0049] The electrode solder joints are distributed in an array on the first surface of the battery cell. For details, please refer to Figure 2 The specific implementation method in .

[0050] Each strip-shaped air outlet outputs welding hot air to weld a plurality of welding strips arranged along a vertical first direction and covering electrode welding points of the battery sheet in the first direction.

[0051] The welding strip 4 extends along the first direction and covers each electrode welding spot 31 distributed along the first direction in the battery cell 3. A plurality of welding strips 4 are arranged perpendicular to the first direction, thereby covering each electrode welding spot 31 on the electrode cell 3.

[0052] like Figure 3 As shown, each cell 3 in the photovoltaic cell moves below the strip-shaped air outlet along the first direction, and continues to move forward after welding is completed until the photovoltaic cell is welded. Figure 3 The direction of the arrow in the middle is the moving direction of each battery cell 3 .

[0053] In some embodiments, welding the welding strip 4 and the electrode welding point 31 corresponding to the welding strip 4 includes:

[0054] The strip-shaped air outlets of the welding device are controlled to synchronously output welding hot air to weld the welding strip 4 and the electrode welding points 31 corresponding to the welding strip 4 .

[0055] The welding device has a hot air conveying mechanism, which controls the hot air to be output synchronously from each strip air outlet. To ensure that the output air volume and output time of the strip air outlet are more consistent, the welding device can control the time and air volume of the welding hot air output by the welding nozzle 2 through the solenoid valve.

[0056] In this embodiment, when welding, the rows of electrode welding points 31 on the battery cell 3 perpendicular to the first direction correspond to each strip air outlet. The strip air outlet heats the area corresponding to the electrode welding point 31, and the portion between two adjacent electrode welding points 31 will not be directly heated by the strip air outlet, so that the expansion of the welding strip 4 during welding can be reduced, and then the shrinkage of the welding strip 4 after cooling can be reduced, so as to achieve the purpose of reducing the warping of the battery cell 3. In addition, each strip air outlet synchronously outputs welding hot air, which can avoid the accumulation of thermal expansion of the welding strip 4 and further reduce the warping of the battery cell 3.

[0057] In some embodiments, the temperature of the welding hot air of each strip-shaped air outlet is greater than or equal to 183°C and less than or equal to 210°C. The welding strip 4 has a hot melt layer, and after heating, the hot melt layer melts, thereby forming an integrated structure with the electrode solder joint 31. In a specific embodiment of the present application, the composition of the hot melt layer is 63% tin and 37% lead, or 60% tin and 40% lead, and the electrode solder joint 31 uses silver paste. After heating, the hot melt layer and the electrode solder joint 31 melt and fuse with each other. After cooling, the two solidify into one. Of course, in other embodiments, the hot melt layer and the electrode solder joint 31 may also use other components or proportions, which are not limited here.

[0058] In this embodiment, the welding hot air from the strip air outlet is more concentrated and the heating range is smaller, which can reduce the heating of the portion of the welding strip 4 located between the electrode welding points 31, thereby reducing the expansion of the welding strip 4 during the welding process and further reducing the warping of the battery cell 3 in the photovoltaic cell.

[0059] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present application, but the present application is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of the present application, and these modifications and improvements are also considered to be within the scope of protection of the present application.

Claims

1. A photovoltaic cell welding device, characterized in that: It includes multiple strip air outlets for outputting welding hot air, and the multiple strip air outlets are arranged in a first direction so that during welding, the multiple strip air outlets respectively correspond to multiple electrode welding points of the battery cell covered by the welding strip extending along the first direction, and the length direction of each strip air outlet is perpendicular to the first direction, so as to weld the multiple welding strips arranged perpendicular to the first direction; more than two strip air outlets are set to weld the electrode welding points in the same row along the first direction, and a single strip air outlet corresponds to the multiple electrode welding points arranged perpendicular to the first direction.

2. The welding device according to claim 1, characterized in that: The welding device is a concentrated hot air heater.

3. The welding device according to claim 1, characterized in that: The width of the strip air outlet is greater than or equal to 2 mm and less than or equal to 4 mm.

4. The welding device according to claim 1, characterized in that: The length of the strip-shaped air outlet is greater than or equal to the distance between two welding strips close to the edge of the battery cell.

5. The welding device according to claim 1, characterized in that: A press is also included, and the press is used to press the welding ribbon to the battery cell when welding the welding ribbon and the electrode welding point.

6. The welding device according to claim 5, characterized in that: The pressing tool is an elastic pressing tool.

7. The welding device according to claim 1, characterized in that: The photovoltaic cell comprises n cells, and the number of rows of the matrix of the electrode welding points on each cell is the same, wherein n is a positive integer greater than or equal to 3; The welding strip includes a first welding strip, a second welding strip and a third welding strip, the first welding strip is used to connect the 2a+1th battery cell and the 2a+2th battery cell from one end of the photovoltaic cell, the second welding strip is used to connect the 2a+2th battery cell and the 2a+3th battery cell, and the third welding strip is arranged on the 1st battery cell and the nth battery cell, and is used to connect the rows of the matrix of the remaining electrode welding points, wherein a is an integer greater than or equal to 0; The first welding strips and the second welding strips are alternately distributed along the column direction of the matrix of the electrode welding points.

8. A photovoltaic cell welding method, applied to the photovoltaic cell welding device according to any one of claims 1 to 7, characterized in that: include: Make the first surface of the battery sheet face the direction of the strip air outlet, and move the battery sheet along the first direction to below the strip air outlet, so that each row of electrode welding points perpendicular to the first direction corresponds to each strip air outlet; Each of the strip-shaped air outlets outputs welding hot air to weld a plurality of welding strips arranged in a vertical first direction and covering electrode welding points of the battery cell in the first direction.

9. The welding method according to claim 8, characterized in that: Each of the strip-shaped air outlets outputs welding hot air to weld a plurality of welding strips arranged in a vertical first direction and covering the electrode welding points of the battery cell in the first direction, including: The strip-shaped air outlets of the welding device are controlled to synchronously output welding hot air, so as to synchronously weld a plurality of welding strips arranged along a vertical first direction and covering the electrode welding points of the battery cell in the first direction.

10. The welding method according to claim 9, characterized in that: The temperature of the welding hot air from each of the strip-shaped air outlets is greater than or equal to 183° C. and less than or equal to 210° C.

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