Solar cell and preparation method thereof

Abstract

The invention relates to the field of photovoltaic technology, in particular to a solar cell and a preparation method thereof. The solar cell comprises a cell piece and a welding material. A plurality of welding spots are formed on the surface of the battery piece; the welding material forms a plurality of welding parts at the welding spots, the welding parts comprise at least three first welding parts and second welding parts, the contour shapes of the first welding parts are different from the contour shapes of the second welding parts, and the first welding parts are used for being recognized by camera equipment to position the positions of the battery pieces. The first welding part on the welding spot is used as the Mark point, so that positioning can be carried out when a new screen printing plate is replaced, the position of the new screen printing plate is convenient to adjust, the new screen printing plate corresponds to the position of the battery piece, the Mark point can be prevented from being directly arranged on the auxiliary grid, and subfissure of the solar battery and corrosion of the auxiliary grid are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic, in particular to a solar cell and a preparation method thereof. BACKGROUND

[0002] In the screen printing process of the solar cell, a new screen needs to be replaced, and the new screen needs to be calibrated and positioned before printing to ensure the accuracy of the printing position of the new screen. SUMMARY

[0003] Therefore, it is necessary to provide a solar cell and a preparation method thereof to solve the problem that the new screen needs to be calibrated and positioned when the new screen is replaced.

[0004] In a first aspect, a solar cell comprises:

[0005] A cell piece, a surface of the cell piece is formed with a plurality of soldering points;

[0006] A soldering material forms a plurality of soldering portions at the plurality of soldering points, the plurality of soldering portions comprises a first soldering portion and a second soldering portion, a contour shape of the first soldering portion is different from a contour shape of the second soldering portion, the number of the first soldering portion is at least 3, and the first soldering portion is used for identification by a camera device to position the cell piece.

[0007] In one of the embodiments, a peripheral contour of all the first soldering portions connected to each other is a polygon, and a diagonal intersection point of the polygon is located on a geometric center of the cell piece; and / or, a center of the first soldering portion coincides with a center of the soldering point.

[0008] In one of the embodiments, the number of the first soldering portion is 4, and the four first soldering portions are arranged at four corners of the cell piece.

[0009] In one of the embodiments, the contour shape of the first soldering portion is at least one of a circle, a square, a rectangle, a diamond, a trapezoid, an ellipse, a triangle, a cross, and a cross shape.

[0010] In one of the embodiments, the contour shape of the first soldering portion is a circle, and a diameter of the first soldering portion is d, and 0.6mm≤d≤0.8mm is satisfied.

[0011] In one of the embodiments, the surface of the battery piece is provided with a main grid, and all the soldering points are located on the main grid. The solar cell further comprises an insulating layer covering at least the main grid. The insulating layer is provided with a hollow portion along the thickness direction of the insulating layer. The soldering points are located in the hollow portion. The thickness of the insulating layer is greater than the thickness of the soldering points and less than or equal to the sum of the thickness of the first soldering portion or the second soldering portion and the thickness of the soldering points.

[0012] In one of the embodiments, the thickness of the first soldering portion is h1, and 60 μm≤h1≤100 μm is satisfied.

[0013] And / or, the thickness of the second soldering portion is h2, and 60 μm≤h2≤100 μm is satisfied.

[0014] And / or, the thickness of the soldering points protruding from the surface of the battery piece is h3, and 4 μm≤h3≤15 μm is satisfied.

[0015] And / or, the soldering material forms at least one third soldering portion on the surface of the battery piece, and the third soldering portion is located outside all the soldering points. The third soldering portion is used for being recognized by the camera device to locate the position of the battery piece.

[0016] In a second aspect, a manufacturing method of the solar cell of the first aspect comprises the following steps:

[0017] S1, providing a battery piece and a first printing screen plate. The surface of the battery piece is provided with a plurality of soldering points. The first printing screen plate is provided with a plurality of screen holes. The plurality of screen holes comprises first screen holes and second screen holes. The shape of the first screen holes is different from the shape of the second screen holes. The number of the first screen holes is at least 3.

[0018] S2, covering the first printing screen plate on the side of the battery piece provided with the soldering points, so that the plurality of screen holes is located opposite to the plurality of soldering points.

[0019] S3, printing soldering material on the side of the first printing screen plate away from the battery piece. The soldering material is correspondingly attached to the plurality of soldering points through the plurality of screen holes. The first soldering portion is formed on the soldering points corresponding to the first screen holes. The second soldering portion is formed on the soldering points corresponding to the second screen holes. The profile shape of the first soldering portion is the same as the shape of the first screen holes. The profile shape of the second soldering portion is the same as the shape of the second screen holes.

[0020] In one of the embodiments, after step S1 and before step S2, the following steps are further included:

[0021] The second printing screen is provided, and the surface of the battery piece is intersected with a plurality of main grids and a plurality of auxiliary grids, and all the welding points are located on the plurality of main grids, and the second printing screen has a plurality of screen slots, and the number of the screen slots is the same as the number of the main grids.

[0022] The second printing screen is provided on the side of the battery piece provided with the welding points, so that each screen slot is respectively located opposite to the part of each main grid located outside the welding point and the plurality of auxiliary grids intersected with each main grid.

[0023] The insulating glue is printed on the side of the second printing screen away from the battery piece, so that the insulating glue is correspondingly attached to the part of each main grid located outside the welding point and the plurality of auxiliary grids intersected with each main grid through each screen slot to form an insulating layer.

[0024] In one embodiment, after the step S3, the method further comprises the following steps: connecting a plurality of solder strips to the first welding part, the second welding part and the insulating layer on each main grid along the extension direction of the main grid.

[0025] The above solar cell, by setting the first welding part and the second welding part at the welding point on the battery piece, since the profile shape of the first welding part is different from the profile shape of the second welding part, the first welding part can be recognized by the camera equipment as a Mark point. The camera equipment recognizes the profile shape of the first welding part to locate the position of the battery piece, and the position of the new screen can be adjusted according to the position of the battery piece, so that the new screen corresponds to the position of the battery piece, thereby ensuring the accuracy of the printing position of the new screen. Since the first welding part is arranged on the welding point and not arranged on the auxiliary grid, the stress concentration area on the surface of the solar cell can be reduced, thereby reducing the hidden cracks, and the corrosion of the positioning point to the auxiliary grid can be reduced. Therefore, the first welding part on the welding point as a Mark point can not only be positioned when the new screen is replaced, but also can reduce the hidden cracks of the solar cell and the corrosion of the auxiliary grid. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by the disclosed drawings without creative labor for those skilled in the art.

[0027] Figure 1 A distribution diagram of a solar cell provided by the embodiments of the present application.

[0028] Figure 2 For Figure 1An enlarged view of the middle R.

[0029] Figure 3 A distribution diagram of the main grid and the auxiliary grid of a solar cell provided by an embodiment of the present application.

[0030] Figure 4 A sectional view along the thickness direction of a solar cell provided by an embodiment of the present application.

[0031] Figure 5 (a) is a partial structure schematic diagram of a solar cell provided by an embodiment of the present application; Figure 5 (b) is a setting schematic diagram of an insulation layer on a solar cell provided by an embodiment of the present application.

[0032] Legend: 100, solar cell; 10, soldering point; 11, end soldering point; 12, middle soldering point; 20, soldering part; 21, first soldering part; 22, second soldering part; 221, end soldering part; 222, middle soldering part; 30, insulation layer; 31, hollow part; 40, third soldering part; 50, soldering ribbon; 200, cell piece; 201, main grid; 202, auxiliary grid. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below in combination with the drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0034] In the screen printing process of the back contact solar cell, a new screen needs to be replaced, and the new screen needs to be calibrated and positioned before printing to ensure the accuracy of the printing position of the new screen. The usual positioning method is to make Mark points (positioning points) on the auxiliary grid of the solar cell in advance for the camera equipment to recognize, and then adjust the position of the new screen. However, since the positioning points protrude from the surface of the auxiliary grid, when the solar cell is subjected to pressure after being made into a photovoltaic module, the protruding positioning points will form an additional stress concentration area, causing the solar cell to crack. In addition, since the positioning points are made on the auxiliary grid, during the high-temperature soldering process of the soldering ribbon and the soldering point, the positioning points will melt under heat, causing a certain degree of corrosion to the auxiliary grid. Therefore, the current positioning points have the problems of causing the solar cell to crack and the electrode to corrode.

[0035] Based on the above problems, please refer to Figures 1 to 5 , in a first aspect, an embodiment of the present application provides a solar cell 100. Please refer to Figure 2The solar cell 100 comprises the cell sheet 200 and solder material. The surface of the cell sheet 200 is formed with a plurality of solder points 10; the solder material forms a plurality of soldered portions 20 at the plurality of solder points 10, the plurality of soldered portions 20 comprises a first soldered portion 21 and a second soldered portion 22, the profile shape of the first soldered portion 21 is different from the profile shape of the second soldered portion 22. Please refer to Figure 1 The number of the first soldered portion 21 is at least 3, and the first soldered portion 21 is used for the camera to recognize to position the location of the cell sheet 200. The above-mentioned solar cell 100, by setting the first soldered portion 21 and the second soldered portion 22 at the solder points 10 on the cell sheet 200, because the profile shape of the first soldered portion 21 is different from the profile shape of the second soldered portion 22, the first soldered portion 21 can be recognized as a Mark point by the camera. The camera recognizes the profile shape of the first soldered portion 21 to position the location of the cell sheet 200, and the location of the new screen plate can be adjusted according to the location of the cell sheet 200, so that the new screen plate corresponds to the location of the cell sheet 200, thereby ensuring the accuracy of the printing position of the new screen plate. Because the first soldered portion 21 is set on the solder point 10 and does not directly contact the sub-grid 202, the concentrated stress area on the surface of the solar cell 100 can be reduced, thereby reducing the hidden cracks, and the corrosion of the Mark point to the sub-grid 202 can be reduced.

[0036] In some embodiments, the solder point 10 is a silver solder point. The solder material is tin paste, which refers to tin-lead system, tin-lead-silver system, tin-lead-bismuth-silicon system and other types of tin paste. The camera corresponds to the number of the first soldered portion 21, so the number of the camera is at least 3.

[0037] Please refer to Figure 1 In the positioning process, in order to improve the positioning effect, a plurality of cameras are set to recognize the Mark point. In some embodiments, the outer periphery profile of all the first soldered portions 21 connected with each other is a polygon, and the intersection of the diagonals of the polygon is located on the geometric center of the cell sheet 200, which can conform to the position distribution of the camera, so that each first soldered portion 21 corresponds to one camera. For example, please refer to Figure 1 The number of the first soldered portion 21 is 4, and the intersection of the diagonals of the quadrilateral formed by connecting the 4 first soldered portions 21 is located on the geometric center of the solar cell 100. The positions of the 4 cameras correspond to the positions of the 4 first soldered portions 21 one by one, and the connecting line of the 4 cameras also forms a quadrilateral, and the intersection of the diagonals of the quadrilateral is also located on the geometric center of the solar cell 100.

[0038] Please refer to Figure 1 In some embodiments, the 4 first soldered portions 21 are arranged at the four corners of the cell sheet 200, which can facilitate the camera to quickly recognize. In some embodiments, the center of the first soldered portion 21 is located at the center of the solder point 10, which can facilitate the camera to compare and recognize.

[0039] In some embodiments, the first welding portion 21 has a contour shape selected from at least one of a circle, a square, a rectangle, a diamond, a trapezoid, an ellipse, and a triangle, which is convenient for the camera to recognize. Figure 1 In some embodiments, the first welding portion 21 has a contour shape of a circle, and a diameter d1 of the first welding portion 21 satisfies 0.6mm≤d1≤0.8mm. The contour shape of the first welding portion 21 is a circle, which has a clear and consistent contour boundary shape, and is convenient for the camera to recognize. Controlling the diameter d1 of the first welding portion 21 within the above range can ensure the recognition size of the camera, meet the recognition requirements of the camera, and reduce the occurrence of printing misalignment. In addition, it can reduce the overflow or uneven phenomenon during printing, facilitate the control of the contour shape of the first welding portion 21, ensure the connection stability of the first welding portion 21 and the solder strip 50, avoid affecting the welding quality, and reduce the welding defects such as false welding. Furthermore, controlling d1 within the above range can reduce the size deviation caused by the manufacturing process. Thus, the above effects are ensured, the area of the first welding portion 21 is reduced, and the material usage of the first welding portion 21 is reduced. Figure 2 For example, the diameter d1 of the first welding portion 21 can be any point value or a value between any two point values within the above range, such as 0.6mm, 0.62mm, 0.64mm, 0.66mm, 0.68mm, 0.7mm, 0.72mm, 0.74mm, 0.76mm, 0.78mm, 0.8mm, etc.

[0040] In some embodiments, the second welding portion 22 has a contour shape selected from at least one of a circle, a square, a rectangle, a diamond, a trapezoid, an ellipse, and a triangle, which is convenient for the camera to recognize.

[0041] In some embodiments, the second welding portion 22 has a contour shape of a circle, and a diameter d2 of the second welding portion 22 satisfies 0.6mm≤d2≤0.8mm. The contour shape of the second welding portion 22 is a circle, which has a clear and consistent contour boundary shape, and is convenient for the camera to recognize. Controlling the diameter d2 of the second welding portion 22 within the above range can ensure the recognition size of the camera, meet the recognition requirements of the camera, and reduce the occurrence of printing misalignment. In addition, it can reduce the overflow or uneven phenomenon during printing, facilitate the control of the contour shape of the second welding portion 22, ensure the connection stability of the second welding portion 22 and the solder strip 50, avoid affecting the welding quality, and reduce the welding defects such as false welding. Furthermore, controlling d2 within the above range can reduce the size deviation caused by the manufacturing process. Thus, the above effects are ensured, the area of the second welding portion 22 is reduced, and the material usage of the second welding portion 22 is reduced. Figure 2 Figure 3 In some embodiments, the second welding portion 22 has a contour shape of a circle, and a diameter d2 of the second welding portion 22 satisfies 0.6mm≤d2≤0.8mm. The contour shape of the second welding portion 22 is a circle, which has a clear and consistent contour boundary shape, and is convenient for the camera to recognize. Controlling the diameter d2 of the second welding portion 22 within the above range can ensure the recognition size of the camera, meet the recognition requirements of the camera, and reduce the occurrence of printing misalignment. In addition, it can reduce the overflow or uneven phenomenon during printing, facilitate the control of the contour shape of the second welding portion 22, ensure the connection stability of the second welding portion 22 and the solder strip 50, avoid affecting the welding quality, and reduce the welding defects such as false welding. Furthermore, controlling d2 within the above range can reduce the size deviation caused by the manufacturing process. Thus, the above effects are ensured, the area of the second welding portion 22 is reduced, and the material usage of the second welding portion 22 is reduced.

[0042] In some embodiments, the welding point 10 has a contour shape selected from at least one of a circle, a square, a rectangle, a diamond, a trapezoid, an ellipse, and a triangle, which is convenient for the camera to recognize. Figure 2 In some embodiments, the welding point 10 has a contour shape of a circle, and a diameter d3 of the welding point 10 satisfies 0.6mm≤d3≤0.8mm. The contour shape of the welding point 10 is a circle, which has a clear and consistent contour boundary shape, and is convenient for the camera to recognize. Controlling the diameter d3 of the welding point 10 within the above range can ensure the recognition size of the camera, meet the recognition requirements of the camera, and reduce the occurrence of printing misalignment. In addition, it can reduce the overflow or uneven phenomenon during printing, facilitate the control of the contour shape of the welding point 10, ensure the connection stability of the welding point 10 and the solder strip 50, avoid affecting the welding quality, and reduce the welding defects such as false welding. Furthermore, controlling d3 within the above range can reduce the size deviation caused by the manufacturing process. Thus, the above effects are ensured, the area of the welding point 10 is reduced, and the material usage of the welding point 10 is reduced. Figure 2 In some embodiments, the welding point 10 has a contour shape of a circle, and a diameter d3 of the welding point 10 satisfies 0.6mm≤d3≤0.8mm. The contour shape of the welding point 10 is a circle, which has a clear and consistent contour boundary shape, and is convenient for the camera to recognize. Controlling the diameter d3 of the welding point 10 within the above range can ensure the recognition size of the camera, meet the recognition requirements of the camera, and reduce the occurrence of printing misalignment. In addition, it can reduce the overflow or uneven phenomenon during printing, facilitate the control of the contour shape of the welding point 10, ensure the connection stability of the welding point 10 and the solder strip 50, avoid affecting the welding quality, and reduce the welding defects such as false welding. Furthermore, controlling d3 within the above range can reduce the size deviation caused by the manufacturing process. Thus, the above effects are ensured, the area of the welding point 10 is reduced, and the material usage of the welding point 10 is reduced.

[0043] Figure 3 ​​The same surface of the battery piece 200 is provided with the main grid 201 and the auxiliary grid 202 intersecting each other, and the plurality of soldering points 10 are located on the main grid 201. In this embodiment, the solar cell 100 can be a back contact solar cell.

[0044] Please refer to Figures 1 to 4 In the embodiment, the extension direction of the main grid 201 is the A direction, the extension direction of the auxiliary grid 202 is the B direction, and the thickness direction is the C direction.

[0045] Please refer to Figure 3 and Figure 4 Taking the back contact solar cell 100 as an example, the main grid 201 and the auxiliary grid 202 of the back contact solar cell 100 are both provided on the back surface. If the solder strip 50 is directly welded with the soldering point 10, the solder strip 50 is easy to be overlapped on the auxiliary grid 202 and cause short circuit. Please refer to Figure 4 In order to avoid short circuit, in some embodiments, the solar cell 100 further comprises an insulating layer 30, the insulating layer 30 at least covers the main grid 201, the insulating layer 30 is provided with a hollow portion 31 penetrating along the thickness direction of the insulating layer 30, and the soldering point 10 is located in the hollow portion 31. The insulating layer 30 can isolate the contact between the solder strip 50 and the auxiliary grid 202. However, the high temperature generated when the solder strip 50 is welded with the soldering point 10 can melt part of the insulating layer 30. In order to avoid the melting degree of the insulating layer 30 being too large and causing the solder strip 50 to be overlapped on the auxiliary grid 202 again to cause short circuit, in some embodiments, the thickness of the insulating layer 30 is greater than the thickness of the soldering point 10. However, such a setting can cause a thickness difference between the soldering point 10 and the insulating layer 30. When the insulating layer 30 supports the solder strip 50, the solder strip 50 is suspended on the soldering point 10 to form a gap.

[0046] Please refer to Figure 4 In some embodiments, the thickness of the insulating layer 30 is greater than the thickness of the soldering point 10, and is less than or equal to the sum of the thickness of the first welding portion 21 or the second welding portion 22 and the thickness of the soldering point 10. Since the first welding portion 21 and the second welding portion 22 are stacked on the soldering point 10, the first welding portion 21 and the second welding portion 22 can be filled between the soldering point 10 and the insulating layer 30, so that the soldering point 10 and the solder strip 50 are connected through the first welding portion 21 or the second welding portion 22. Therefore, the first welding portion 21 can also improve the insulation effect of the solar cell 100 and avoid short circuit.

[0047] Please refer to Figure 4In some embodiments, the thickness of the insulation layer 30 is h4, which satisfies 40 μm≤h4≤80 μm. The thickness of the insulation layer 30 is kept within the above range, which can guarantee the insulation effect and prevent the short circuit when the solder strip 50 is welded. For example, h4 can be any value within the above range or a value between any two values within the above range, such as 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, etc. For example, the insulation layer 30 can be made of an insulation material such as ethylene-vinyl acetate copolymer, polyolefin elastomer, polyvinyl butyral, polyethylene terephthalate, polycarbonate, polyvinyl fluoride, polyvinylidene fluoride, etc.

[0048] Please refer to Figure 4 In some embodiments, the thickness of the solder joint 10 protruding from the surface of the solar cell 100 is h3, which satisfies 4 μm≤h3≤10 μm. In this way, on the one hand, the material use of the solder joint 10 can be saved and the cost can be reduced; on the other hand, the thickness difference between the solder joint 10 and the insulation layer 30 can be formed to guarantee the insulation effect of the insulation layer 30 on the solder joint 10 and the sub-grid 202 and to avoid short circuit. For example, h3 can be any value within the above range or a value between any two values within the above range, such as 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0049] Please refer to Figure 4 In some embodiments, the thickness of the first welding portion 21 is h1, which satisfies 60 μm≤h1≤100 μm. The thickness of the second welding portion 22 is h2, which satisfies 60 μm≤h2≤100 μm. The thickness of the first welding portion 21 and the second welding portion 22 is controlled within the above range, which can guarantee the stability of the connection with the solder strip 50 and improve the insulation effect of the insulation layer 30. For example, h1 and h2 can be any value within the above range or a value between any two values within the above range, such as 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, etc.

[0050] Please refer to Figure 2 In some embodiments, the second welding portion 22 includes an end welding portion 221 and a middle welding portion 222. Please refer to Figure 1 and Figure 3The end welding portion 221 is located at both ends of the main grid 201 along the length direction of the main grid 201, and the middle welding portion 222 is located at the middle of the main grid 201. The area of the end welding portion 221 is greater than that of the middle welding portion 222. The end welding portion 221 is close to the edge of the solar cell 100 and is easily affected by stress concentration. The end welding portion 221 with a large area can be used to disperse stress and avoid the breakage of the solder strip 50. In addition, the current on the solar cell 100 is transmitted to the external circuit from both ends of the main grid 201. The current density of the end welding portion 221 is high, and a large conductive area can reduce resistance and heat loss and ensure current transmission.

[0051] Please refer to Figure 2 and Figure 3 In some embodiments, along the extension direction of the main grid 201, the size d2 of the end welding portion 221 satisfies: 0.9mm≤d2≤1.3mm; and along the extension direction of the sub-grid 202 of the solar cell 100, the size d3 of the end welding portion 221 satisfies: 0.6mm≤d3≤1.0mm. Controlling the sizes d2 and d3 of the end welding portion 221 within the above range can make the area of the end welding portion 221 larger than that of the first welding portion 21, so that the end welding portion 221 can form a clear difference with the first welding portion 21, thereby facilitating the camera to identify the first welding portion 21. On the other hand, the end welding portion 221 with a large area can provide a larger contact area, enhance the bonding force between the solder strip 50 and itself, improve the stability of the solder strip 50 connection, reduce welding defects such as false welding, and ensure the welding quality. The longer d2 can disperse stress and reduce the breakage of the solder strip 50.

[0052] For example, d2 can be any point value or a value between any two point values within the above range, such as 0.9mm, 0.95mm, 1.0mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, etc. d3 can be any point value or a value between any two point values within the above range, such as 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1.0mm, etc.

[0053] Please refer to Figure 2In some embodiments, the size of the intermediate soldering portion 222 along the extension direction of the main grid 201 is d4, which satisfies: 0.6mm≤d4≤1.0mm; and the size of the intermediate soldering portion 222 along the extension direction of the auxiliary grid 202 of the solar cell 100 is d5, which satisfies: 0.6mm≤d5≤1.0mm. Controlling the size of the intermediate soldering portion 222 within the above range can ensure the stability of the soldering between the intermediate soldering portion 222 and the solder strip 50. For example, d4 and d5 can be any value within the above range or a value between any two values within the above range, such as 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1.0mm, etc.

[0054] Referring to Figure 2 In some embodiments, the soldering point 10 includes an end soldering point 11 and an intermediate soldering point 12. The end soldering point 11 is located at both ends of the main grid 201 along the length direction of the main grid 201, and the intermediate soldering point 12 is located at the middle of the main grid 201. The area of the end soldering point 11 is larger than that of the intermediate soldering point 12. The end soldering point 11 is close to the edge of the solar cell 100 and is easily affected by stress concentration. Setting the end soldering point 11 with a larger area can be used to disperse stress and avoid the breakage of the solder strip 50, thereby improving the stability of the connection between the solder strip 50. In addition, the current on the solar cell 100 is transmitted to the external circuit from both ends of the main grid 201. The current density of the end soldering point 11 is higher, and setting a larger conductive area can reduce the resistance and heat loss, thereby ensuring the current transmission.

[0055] Referring to Figure 2 In some embodiments, the size of the end soldering point 11 along the extension direction of the main grid 201 is d6, which satisfies: 1.5mm≤d6≤1.9mm; and the size of the end soldering point 11 along the extension direction of the auxiliary grid 202 of the solar cell 100 is d7, which satisfies: 1.0mm≤d7≤1.4mm.

[0056] For example, d6 can be any value within the above range or a value between any two values within the above range, such as 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, etc. For example, d7 can be any value within the above range or a value between any two values within the above range, such as 1.0mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, etc.

[0057] Referring to Figure 2In some embodiments, the size of the intermediate soldering point 12 along the extension direction of the main grid 201 is d8, which satisfies: 1.0mm≤d8≤1.4mm; and the size of the intermediate soldering point 12 along the extension direction of the sub-grid 202 of the solar cell 100 is d9, which satisfies: 1.0mm≤d9≤1.4mm. In this way, the area of the soldering point 10 is larger than the area of the second soldering part 22 and the first soldering part 21, which can reduce the material usage of the second soldering part 22 and the first soldering part 21, and can reduce the cost while meeting the positioning and identification accuracy and the soldering stability. In addition, if the area of the soldering point 10 is too small, the printing material can overflow the soldering point 10 during the printing of the second soldering part 22 and the first soldering part 21, which can cause poor soldering or short circuit.

[0058] For example, d8 can be any value within the above range or a value between any two values within the above range, such as 1.0mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, etc. For example, d9 can be any value within the above range or a value between any two values within the above range, such as 1.0mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, etc.

[0059] In some embodiments, the width of the solder strip 50 is d 10 , which satisfies: 0.4mm≤d 10 ≤0.6mm (d 10 is not shown in the figure). The width of the solder strip 50 is smaller than or equal to the size of the first soldering part 21 and the second soldering part 22, which can reduce the influence of the different shapes of the first soldering part 21 and the second soldering part 22 on the soldering quality, and can ensure the soldering quality of the first soldering part 21 and the solder strip 50. If the width of the solder strip 50 is too wide, it can increase the area of the solar cell 100 that is blocked from the sunlight, reduce the light absorption of the solar cell 100, and further cause part of the solder strip 50 not to be soldered with the first soldering part 21, which can affect the soldering quality. If the width of the solder strip 50 is too narrow, it can be more easily broken. For example, the width d 10 of the solder strip 50 can be any value within the above range or a value between any two values within the above range, such as 0.4mm, 0.42mm, 0.45mm, 0.47mm, 0.5mm, 0.52mm, 0.55mm, 0.56mm, 0.6mm, etc.

[0060] For example, the width of the solder strip 50 can be any value within the above range or a value between any two values within the above range, such as 0.4mm, 0.42mm, 0.45mm, 0.47mm, 0.5mm, 0.52mm, 0.55mm, 0.56mm, 0.6mm, etc. Figure 3In some embodiments, the welding material forms at least one third welding portion 40 on the surface of the battery piece 200, the third welding portion 40 is located outside all the welding points 10, and the third welding portion 40 is used for being recognized by the camera equipment to locate the position of the battery piece 200. The third welding portion 40 can also be used as a Mark point for the camera equipment to recognize. The number of the first welding portion 40 can be one, two, three, etc.

[0061] Please refer to Figure 3 In some embodiments, the third welding portion 40 has a circular shape, and the diameter of the third welding portion 40 is d 11 , which satisfies: 0.2mm≤d 11 ≤0.5mm. For example, the diameter d 11 of the third welding portion 40 can be any point value in the above range or a value between any two point values, such as 0.2mm, 0.24mm, 0.28mm, 0.32mm, 0.36mm, 0.40mm, 0.44mm, 0.48mm, 0.5mm, etc.

[0062] In summary, the first welding portion 21 in the embodiments of the present application has the following comprehensive effects: the first welding portion 21 not only can be used as a Mark point of the new screen plate when the new screen plate is replaced, so as to facilitate the adjustment of the relative position of the new screen plate and the battery piece 200, but also can be used as a filler to fill the gap between the welding strip 50 and the welding point 10, so as to ensure the stable connection of the welding strip 50 and the welding point 10, ensure the insulation effect of the insulation layer 30, and avoid short circuit. Since the first welding portion 21 on the welding point 10 is directly used as the Mark point of the replaced screen plate, no Mark point is additionally provided on the sub-grid 202, which can reduce the material used for the additional Mark point, reduce the cost, reduce the additional corrosion of the sub-grid 202, reduce the additional stress concentration area, and thus reduce the hidden cracks.

[0063] In a second aspect, the embodiments of the present application also provide a manufacturing method of a solar cell 100, which comprises the following steps:

[0064] S1, providing a battery piece 200 and a first printing screen plate, the surface of the battery piece 200 forms a plurality of welding points 10, and the first printing screen plate has a plurality of screen holes, the plurality of screen holes includes a first screen hole and a second screen hole, the shape of the first screen hole is different from that of the second screen hole, and the number of the first screen hole is at least three;

[0065] S2, the first printing screen plate is arranged on one side of the battery piece 200 provided with the welding points 10, so that the plurality of screen holes are located opposite to the plurality of welding points 10;

[0066] S3, printing the soldering material on the side of the first printing screen away from the battery piece 200, so that the soldering material is attached to the plurality of soldering points 10 through the plurality of screen holes, wherein the first soldering part 21 is formed on the soldering point 10 corresponding to the first screen hole, the second soldering part 22 is formed on the soldering point 10 corresponding to the second screen hole, the profile shape of the first soldering part 21 is the same as the shape of the first screen hole, and the profile shape of the second soldering part 22 is the same as the shape of the second screen hole.

[0067] It should be noted that the first printing screen in this embodiment refers to a printing screen that has been accurately positioned with the battery piece 200, while the position of the new screen is random and needs to be adjusted to align with the position of the battery piece 200. The first soldering part 21 formed as a Mark point by the first printing screen can be used to position the installed new screen, so that the position of the new screen can be adjusted. The new screen is also at least 3 screen holes with different profile shapes from other screen holes, and the number of screen holes with different profile shapes on the new screen is the same as that of the first soldering part 21. When adjusting the position of the new screen, the screen holes with different profile shapes on the new screen are compared with the first soldering part 21 on the battery piece 200, and the offset screen holes are aligned with the first soldering part 21, so that the offset new screen is aligned with the battery piece 200. When the position of the new screen is adjusted, the subsequent battery piece 200 is printed with the soldering material while maintaining the adjusted position, and the first soldering part 21 and the second soldering part 22 are continuously formed on the subsequent battery piece 200.

[0068] Please refer to Figure 5 In some embodiments, after step S1 and before step S2, the following steps are further included:

[0069] A second printing screen is provided, the surface of the battery piece 200 is provided with a plurality of main grids 201 and a plurality of auxiliary grids 202, and all the soldering points 10 are located on the plurality of main grids 201, the second printing screen has a plurality of screen grooves, and the number of screen grooves is the same as the number of main grids 201;

[0070] The second printing screen is arranged on the side of the battery piece 200 provided with the soldering points 10, so that each screen groove is respectively located opposite to the part of the main grid 201 outside the soldering point 10 and the plurality of auxiliary grids 202 intersecting with the main grid 201;

[0071] In the second printing screen, the insulating glue is printed on the side away from the battery piece 200, and the insulating glue is attached to the part of each main grid 201 outside the soldering point 10 and the plurality of sub-grids 202 intersecting with each main grid 201 through each screen slot to form the insulating layer 30. If the step of setting the insulating layer 30 is after the steps of making the first soldering part 21 and the second soldering part 22, the thickness of the insulating layer 30 cannot be controlled, the thickness of the insulating layer 30 is greater than the sum of the thicknesses of the first soldering part 21 or the second soldering part 22 and the soldering point 10, and further, a gap is generated between the insulating layer 30 and the first soldering part 21 and the second soldering part 22, which cannot guarantee that the soldering point 10 is connected with the soldering ribbon 50 through the first soldering part 21 and the second soldering part 22. Please refer to Figure 5 Since the insulating glue is attached to the part of each main grid 201 outside the soldering point 10 and the plurality of sub-grids 202 intersecting with each main grid 201 through each screen slot to form the insulating layer 30, the periphery of the soldering point 10 is provided with the insulating layer 30, and further, when the soldering ribbon 50 is soldered, the soldering ribbon 50 can be prevented from connecting the sub-grids 202 of opposite polarities near each main grid 201 to each other, and short circuit is avoided.

[0072] Please refer to Figure 5 It should be noted that each screen slot includes a first part, a second part and a third part. The shape of the first part corresponds to the shape of the main grid 201 outside the soldering point 10. The shape of the second part is a ring shape surrounding the periphery of the soldering point 10. The shape of the third part corresponds to the shape of the sub-grid 202 intersecting with the main grid 201.

[0073] In some embodiments, after the step S3, the method further includes the following step: connecting the plurality of soldering ribbons 50 with the first soldering part 21 and the second soldering part 22 on each main grid 201 in the extension direction of the main grid 201. In this way, on the one hand, the connection strength of the soldering ribbon 50 can be guaranteed, and on the other hand, the insulating effect of the soldering ribbon 50 can be improved.

[0074] In the description of the present application, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0075] In addition, the terms "first", "second", and the like, if any, are used herein for descriptive purposes only and should not be construed as indicating or implying relative importance or identifying the number of the indicated technical characteristics. Thus, a feature with the "first", "second" limitation can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0076] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be interpreted broadly. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0077] In the present application, unless otherwise explicitly specified and limited, if the first feature is described as "on" or "under" the second feature, etc., it can mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be the first feature directly above or obliquely above the second feature, or only indicates that the horizontal thickness of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be the first feature directly below or obliquely below the second feature, or only indicates that the horizontal thickness of the first feature is less than that of the second feature.

[0078] It should be noted that if an element is referred to as "fixed to" or "provided on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are only for illustrative purposes and do not represent the only implementation.

[0079] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combination of the technical features does not exist Contradiction, it should be considered within the scope of the present application.

[0080] The above embodiments only express several implementation ways of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation to the patent scope of the application. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A solar cell (100), characterized in that, include: A battery cell (200) having a plurality of solder joints (10) formed on its surface; The welding material forms multiple weld portions (20) at multiple weld points (10). The multiple weld portions (20) include a first weld portion (21) and a second weld portion (22). The outline shape of the first weld portion (21) is different from that of the second weld portion (22). The number of the first weld portions (21) is at least 3. The first weld portions (21) are used for identification by a camera device to locate the position of the battery cell (200).

2. The solar cell (100) according to claim 1, characterized in that, The outer contour of all the first welded portions (21) connected to each other is a polygon, and the intersection of the diagonals of the polygon is located at the geometric center of the battery cell (200); and / or, the center of the first welded portion (21) coincides with the center of the weld point (10).

3. The solar cell (100) according to claim 1, characterized in that, There are four first welding parts (21), which are located at the four corners of the battery cell (200).

4. The solar cell (100) according to claim 1, characterized in that, The outline shape of the first welded part (21) is at least one of the following: circle, rectangle, long rectangle, rhombus, trapezoid, ellipse, and triangle.

5. The solar cell (100) according to claim 4, characterized in that, The outline shape of the first welded part (21) is circular, and the diameter of the first welded part (21) is d1, which satisfies: 0.6mm≤d1≤0.8mm.

6. The solar cell (100) according to claim 1, characterized in that, The surface of the solar cell (200) is provided with a main grid (201), and all the solder joints (10) are located on the main grid (201). The solar cell (100) also includes an insulating layer (30), which at least covers the main grid (201). The insulating layer (30) has a hollow portion (31) extending through it along its thickness direction. The solder joints (10) are located in the hollow portion (31). The thickness of the insulating layer (30) is greater than the thickness of the solder joint (10), and is less than or equal to the sum of the thickness of the first weld portion (21) or the second weld portion (22) and the thickness of the solder joint (10).

7. The solar cell (100) according to any one of claims 1 to 6, characterized in that, The thickness of the first welded part (21) is h1, which satisfies: 60μm≤h1≤100μm; And / or, the thickness of the second weld (22) is h2, satisfying: 60μm≤h2≤100μm; And / or, the thickness of the solder joint (10) protruding from the surface of the battery cell (200) is h3, satisfying: 4μm≤h3≤15μm; And / or, the welding material forms at least one third welding portion (40) on the surface of the battery cell (200), the third welding portion (40) being located outside all the welding points (10), the third welding portion (40) being used to be identified by the camera device to locate the position of the battery cell (200).

8. A method for manufacturing a solar cell (100) as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Provide a battery cell (200) and a first printing screen. The surface of the battery cell (200) has a plurality of solder joints (10). The first printing screen has a plurality of mesh holes, including a first mesh hole and a second mesh hole. The shape of the first mesh hole is different from the shape of the second mesh hole, and the number of the first mesh holes is at least 3. S2. The first printing screen is applied to the side of the battery cell (200) where the solder joints (10) are located, so that the plurality of mesh holes are aligned with the plurality of solder joints (10); S3. Print welding material on the side of the first printing screen facing away from the battery cell (200), so that the welding material is attached to the multiple welding points (10) through the multiple mesh holes. A first welding part (21) is formed on the welding point (10) corresponding to the first mesh hole, and a second welding part (22) is formed on the welding point (10) corresponding to the second mesh hole. The outline shape of the first welding part (21) is the same as the shape of the first mesh hole, and the outline shape of the second welding part (22) is the same as the shape of the second mesh hole.

9. The manufacturing method according to claim 8, characterized in that, After step S1 and before step S2, the following steps are also included: A second printing screen is provided, wherein a plurality of main grids (201) and a plurality of sub-grids (202) are intersecting on the surface of the battery cell (200), all of the solder joints (10) are located on the plurality of main grids (201), and the second printing screen has a plurality of screen grooves, the number of which is the same as the number of main grids (201); The second printing screen is applied to the side of the battery cell (200) where the solder joint (10) is located, so that each of the screen grooves is positioned opposite to the portion of a main grid (201) located outside the solder joint (10) and to the multiple sub-grids (202) intersecting with a main grid (201); Insulating adhesive is printed on the side of the second printing screen facing away from the battery cell (200), so that the insulating adhesive is attached to the portion of each main grid (201) outside the solder joint (10) and to the multiple sub-grids (202) intersecting with each main grid (201) to form an insulating layer (30).

10. The manufacturing method according to claim 9, characterized in that, Following step S3, the following steps are also included: along the extension direction of the main gate (201), a plurality of solder strips (50) are respectively connected to the first solder portion (21), the second solder portion (22) and the insulating layer (30) on each of the main gates (201).

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