Solar cell and printing screen

Abstract

The application provides a solar cell and a printing screen plate, and relates to the technical field of photovoltaics. The solar cell comprises a cell piece, a plurality of fine grids, a plurality of main grids, a fishing rod structure connected to each of the two ends, a conductive connection point located at the connection between each main grid and the fishing rod structure, a first gradient connection structure located at a target area, and a second gradient connection structure located outside the target area. The height of the first gradient connection structure is lower than the height of the second gradient connection structure, the target area is the connection between a target fine grid and each main grid, and the target fine grid is at least one adjacent fine grid adjacent to the conductive connection point along the center direction of the corresponding main grid. By reducing the height of the first gradient connection structure on the target fine grid at the two ends, the problem of empty welding of the welding strip at the two ends of the solar cell is improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and more particularly to a solar cell and a printing screen. Background Technology

[0002] Solar cells are widely used due to their clean and environmentally friendly characteristics. The manufacturing of solar cells mostly uses screen printing to laminate and sinter metal pastes, forming metallized patterns on the front and back of the solar cell for carrier transport and collection. Currently, screen printing is mainly done in steps (DUP), with the main grid printed in rows 1 & 3 and the fine grid in rows 2 & 4. The main grid is primarily made of non-burn-through glass, mainly serving to provide tensile strength during welding and to conduct current, as its shaping requirements are not high. Considering cost, the fine grid is mainly made of burn-through glass, which has better shaping properties and contact with the silicon substrate than the main grid paste. However, the main grid has significantly lower solids content and linewidth compared to the fine grid paste. Currently, in order to improve efficiency, the graphic design of solar cell metal electrodes involves printing the gradient connection structure (such as centipede legs) between the main grid and the fine grid on the fine grid. Due to the characteristics of the fine grid paste and the screen, the printing height is relatively high, causing the centipede leg plane to be 3-4μm higher than the main grid connection line. This makes it easy for the solder ribbon to have void soldering at the beginning and end of the solar cell. Utility Model Content

[0003] To alleviate, reduce, or eliminate the aforementioned technical problems, this application provides a solar cell and a printing screen that improves the problem of void soldering at the beginning and end, thereby increasing cell efficiency.

[0004] In a first aspect, this application provides a solar cell, comprising:

[0005] The battery cell comprises: multiple fine grids, multiple main grids, a harpoon structure connecting each grid to its two ends, conductive connection points located at the connection between each main grid and the harpoon structure, a first gradient connection structure located in the target area, and a second gradient connection structure located outside the target area. The height of the first gradient connection structure is lower than the height of the second gradient connection structure. The target area is the connection between the target fine grid and each main grid, and the target fine grid is at least one adjacent fine grid adjacent to the conductive connection point along the center direction of the corresponding main grid.

[0006] Secondly, this application provides a printing screen, comprising:

[0007] The main grid screen includes multiple main grids, a harpoon structure connected to both ends of each main grid, a conductive connection point located at the connection between each main grid and the harpoon structure, and a first gradient connection structure located in the target area. The target area is the connection between the target fine grid and each main grid, and the target fine grid is at least one adjacent fine grid adjacent to the conductive connection point along the center direction of the corresponding main grid.

[0008] A fine grid plate, comprising multiple fine grids and a second gradient connection structure located outside the target area;

[0009] The first gradient connection structure and the second gradient connection structure are both used to connect the corresponding main gate and the corresponding fine gate.

[0010] This application reduces the probability of void soldering at the beginning and end of the solar cell by lowering the height of the first gradient connection structure on the target grid adjacent to the first and last conductive connection points. Attached Figure Description

[0011] The accompanying drawings are included to provide a further understanding of this application; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application. In the drawings:

[0012] Figure 1 This is a schematic diagram of a solar cell;

[0013] Figure 2 yes Figure 1 A partial schematic diagram of point A in the middle;

[0014] Figure 3 This is a schematic diagram of solar cells connected in series;

[0015] Figure 4 This is a partial schematic diagram of the fine grid distribution in a solar cell;

[0016] Figure 5 This is a schematic diagram of the main grid distribution of a solar cell;

[0017] Figure 6 This is a schematic diagram of a solar cell provided in an embodiment of this application;

[0018] Figure 7 This is provided by the embodiments of this application. Figure 6 A partial schematic diagram at point B1;

[0019] Figure 8 This is a partial schematic diagram of a solar cell provided in an embodiment of this application;

[0020] Figure 9 This is a partial side view of a solar cell;

[0021] Figure 10 This is a partial side view of a solar cell provided in an embodiment of this application;

[0022] Figure 11 This is a schematic diagram of a solar cell grid electrode provided in an embodiment of this application;

[0023] Figure 12 yes Figure 11 A partial schematic diagram at point C. Detailed Implementation

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be used to apply this application to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0025] As indicated in this application, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified elements, which do not constitute an exclusive list, and the device may also include other elements.

[0026] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components illustrated in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0027] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application.

[0028] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0029] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0030] It should be understood that when a component is referred to as "on another component," "connected to another component," "coupled to another component," or "in contact with another component," it can be directly on, connected to, coupled to, or in contact with that other component, or there may be an inserting component. In contrast, when a component is referred to as "directly on another component," "directly connected to," "directly coupled to," or "directly in contact with" another component, there is no inserting component.

[0031] A solar cell is a thin-film photovoltaic semiconductor that directly generates electricity using sunlight. Also known as a "solar chip" or "photovoltaic cell," it can instantly output voltage and generate current when the illumination conditions are met. The solar cell is the basic building block of a solar cell, formed by forming grid electrodes on the surface of a substrate. These grid electrodes collect the photocurrent. The grid electrodes of a solar cell typically include a main grid and fine grids. The photocurrent is transmitted through the fine grids to the main grid, and then conducted out through the solder ribbon.

[0032] See Figures 1-5 , Figure 1This is a schematic diagram of solar cell 10. Figure 2 for Figure 1 A partial schematic diagram at point A in the middle. Figure 3 for Figure 1 A schematic diagram of 10 solar cells connected in series. Figure 4 This is a partial schematic diagram of the fine grid distribution in solar cell 10. Figure 5 This is a schematic diagram of the main grid distribution in solar cell 10. (See diagram below.) Figure 1 As shown, the solar cell 10 includes a cell 100, a plurality of fine grids 101 arranged side by side at intervals, a solder strip 102, and each main grid ( Figure 1 (Not shown, but overlapping with the solder strip 102) Two conductive connection points 103 at the beginning and end of the main gate. The two conductive connection points 103 may include, for example, a first solder point (i.e., the first PAD point) and a last solder point (i.e., the last PAD point), which refer to the solder points located at the beginning and end of the main gate, respectively, for connecting with the solder strip to realize the conduction of current.

[0033] Currently, to improve efficiency, the gradient connection structure between the main grid and the fine grid in solar cell 10 is entirely printed on the fine grid. For example... Figure 4 and Figure 5 As shown, all the gradient connection structures are located on the fine gate, including Figure 4 Multiple gradient connection structures 1040 in region 104 and multiple gradient connection structures 1050 in region 105, Figure 5 The main gate 106 does not include any gradient connection structure. This gradient connection structure, which can be called a centipede foot, is a gradually thickened connecting line at the overlap of the main gate and the fine gate. The line is thicker closer to the end of the fine gate cut-off point. Its main function is to connect the main gate and the fine gate and prevent the fine gate from being melted during the welding process.

[0034] Due to the characteristics of the fine grid paste and screen printing plate, the fine grid printing height is relatively high. The gradient connection structure, printed on the fine grid, results in the gradient connection structure plane being 3-4 μm higher than the main grid. Furthermore, because solar cell welding typically employs… Figure 3 In the front-to-back, end-to-end connection configuration shown, the welding stress is mainly concentrated at the beginning and end of the solar cell welding points. In this case, the welding joints between the solder strip 102 and the corresponding first and last conductive connection points 103 on the main grid are prone to incomplete welds, such as… Figure 2 As shown.

[0035] To address the aforementioned problems of solar cells (such as solar cell 10 described above), this application provides a solar cell in which multiple solar cells can be electrically connected to form a cell string to constitute a photovoltaic module. The solar cell includes a cell, multiple fine grids, multiple main grids, a harpoon structure connected to each of the beginning and end points, a conductive connection point located at the connection between each main grid and the harpoon structure, a first gradient connection structure located in a target area, and a second gradient connection structure located outside the target area. The height of the first gradient connection structure is lower than the height of the second gradient connection structure. The target area is the connection point between the target fine grid and each main grid, and the target fine grid is at least one adjacent fine grid adjacent to the conductive connection point along the center direction of the corresponding main grid. By reducing the height of the first gradient connection structure on the beginning and end target fine grids, the problem of incomplete soldering at the beginning and end of the solar cell is improved.

[0036] In one embodiment, the number of the aforementioned target fine gates is 3-10. For example, see... Figures 6-8 The solar cell proposed in this application includes a cell 600, a plurality of fine grids 601 arranged side by side along a first direction, a plurality of main grids 602 arranged side by side along a second direction, a harpoon structure 603 connected to the two ends of each main grid 602, two conductive connection points 604 (such as the first PAD point and the last PAD point) located at the connection between each main grid 602 and the harpoon structure 603, and three target fine grids (including) adjacent to the conductive connection points 604 along the center direction of each main grid 602. Figure 8 The first gradient connection structure 606 on the three fine grids arranged side by side at intervals along the first direction in region 605 is located at the connection between the target fine grid and the corresponding main grid 602. The first direction and the second direction intersect, which can be a perpendicular intersection as shown in the figure, or other forms of intersection, without specific limitation.

[0037] Understandably, the patterns at both ends of each main gate 602 are completely symmetrical, so that... Figure 6 and Figure 7 For example, Figure 6 The patterns at B1 and B2 are completely symmetrical. Each main gate 602 is provided with a harpoon structure 603, a conductive connection point 604 at the beginning / end, and three first gradient connection structures 606 arranged side by side along the first direction from the edge of the first end / end towards the center of the main gate 602. The fork lines of the harpoon structure 603 extend toward the edge of the main gate 602.

[0038] In addition, the solar cell also includes multiple second gradient connection structures 607 (including Figure 8All the second gradient connection structures 607 in regions 608 and 609 include N second gradient connection structures 607 arranged side-by-side and spaced apart along the second direction on a single grid, where N is the same as the total number of main grids in the solar cell. Figure 6 For example, a solar cell has 16 main grids, and correspondingly, Figure 8 Each fine grid in regions 608 and 609 has 16 second gradient connection structures 607 arranged side by side along the second direction, and each second gradient connection structure 607 is used to connect the corresponding main grid and the corresponding fine grid.

[0039] Figure 8 The cut-off points of the first, second, and fifth fine grids, counting from the beginning to the end of the main grid, are electrically connected through the harpoon structure 603 on the corresponding main grid. The cut-off point of the sixth fine grid is electrically connected through the head conductive connection point 604 on the corresponding main grid. The cut-off points of the third and fourth fine grids are connected through multiple second gradient connection structures 607 arranged side by side along the first direction on the fine grid (including all the second gradient connection structures 607 in region 608, which can be called harpoon-shaped fine grids).

[0040] The fine grid 601 and the second gradient connection structure 607 are printed on the fine grid screen. Due to the characteristics of the main grid, fine grid paste, and screen, the printing height is higher than that of the main grid. The main grid 602, the harpoon structure 603, the conductive connection points 604 at the head / tail end, and the first gradient connection structure 606 are printed on the main grid screen, and the printing height is lower than that of the fine grid. By using this method, the height of the first gradient connection structure 606 can be lower than that of the second gradient connection structure 607.

[0041] In one embodiment, the height difference between the first gradient connecting structure 606 and the second gradient connecting structure 607 can be 1-5 μm. For example, the height of the first gradient connecting structure 606 is 5-7 μm, and the height of the second gradient connecting structure is 8-10 μm.

[0042] In one embodiment, the linewidth of the first gradient connection structure 606 is greater than the linewidth of the second gradient connection structure 607, and the linewidth difference between the first gradient connection structure 606 and the second gradient connection structure 607 can be 10-40 μm. For example, the linewidth of the first gradient connection structure 606 can be 50-70 μm, and the linewidth of the second gradient connection structure 607 can be 30-60 μm.

[0043] See also Figure 9 and Figure 10 , Figure 9 This is a partial side view of solar cell 10 (along the main grid direction). Figure 10 This is a partial side view (along the main grid direction) of the solar cell proposed in this application.Figure 9 The gradient connection structure in Figure 10 The first and second gradient connection structures are the same; both can be centipede legs. Figure 9 In this design, all gradient connection structures are formed using a fine-grid printing plate, resulting in a higher overall height; the first / last end conductive connection points are formed using a main-grid printing plate, resulting in a lower overall height. Figure 10 In the first image, the second gradient connection structure is formed on the fine grid screen, resulting in a higher overall height; the first / tail conductive connection points, and the first gradient connection structures on the three target fine grids adjacent to the first / tail conductive connection points (hereinafter referred to as the first / tail gradient connection structures), are formed on the main grid screen, resulting in a lower overall height. (Comparison) Figure 9 and Figure 10 As can be seen, compared with the solar cell 10 known to the applicant, the solar cell proposed in this application significantly reduces the height of the end-to-end gradient connection structure, and the welding joint between the solder strip and the conductive connection point at the beginning / end is subjected to less tensile force, which helps to reduce the probability of void soldering at the beginning and end of the solar cell.

[0044] Another embodiment of this application proposes a printing screen for a solar cell, comprising: a main grid screen, the main grid screen including a plurality of main grids, a harpoon structure connected to both ends of each main grid, a conductive connection point located at the connection between each main grid and the harpoon structure, and a first gradient connection structure located in a target region. The target region is the connection point between a target fine grid and each main grid, and the target fine grid is at least one adjacent fine grid adjacent to the conductive connection point along the center direction of the corresponding main grid.

[0045] In addition, the printing screen also includes a fine grid screen, which comprises multiple fine grids and a second gradient connection structure located outside the aforementioned target area. Both the first and second gradient connection structures are used to connect the corresponding main grids and the corresponding fine grids. The solar cell proposed in this application embodiment can be printed using this printing screen.

[0046] For example, the graphic design of the main grid version is as follows: Figure 6 As shown, the graphic design of the fine grid version is as follows: Figure 8 As shown. See also Figures 6-8 The main grid pattern includes multiple main grids 602 arranged side-by-side at intervals along a second direction, each main grid 602 extending towards its beginning and end edges along a first direction. The beginning and end edge regions of each main grid 602 are divided into a beginning edge region and a end edge region, and the graphic design in the two regions is completely symmetrical, such as... Figure 6The B1 (i.e., the first edge region) and B2 (i.e., the last edge region) are located in the grid. Taking B1 as an example, from the first edge of the corresponding main gate 602 inwards, there are a harpoon structure 603, a first conductive connection point 604, and three first gradient connection structures 606. Each of the three first gradient connection structures 606 is located between the main gate 602 and the three target fine gates (including...). Figure 8 The connection point of the three fine grids arranged side by side at intervals along the first direction in region 605.

[0047] like Figure 8 As shown, the fine grid pattern may include a plurality of fine grids 601 arranged side by side at intervals along a first direction, the plurality of fine grids 601 passing through, as shown in the figure Figure 6 The multiple main gates 602 are shown. (Through...) Figure 6 and Figure 8 The grid electrodes (main and fine grid combined) of the solar cell are printed using the corresponding main grid and fine grid stencils, respectively. Figure 11 and Figure 12 As shown, fine grids 610, 611 and 612 are three adjacent fine grids adjacent to the conductive connection point 604 along the center direction of the corresponding main grid 602, i.e. target fine grids. The first gradient connection structure 606 at the connection between fine grids 610, 611 and 612 and each main grid is formed by screen printing on the main grid.

[0048] As can be seen, the printing screen proposed in this application embodiment will display the target fine grids (such as...) in the beginning and end edge regions. Figure 8 All the first gradient connection structures on the three fine grids included in region 605 are transferred to the main grid plate (such as...). Figure 6 and Figure 7 (As shown). When the grid electrodes of the solar cell are subsequently printed using this printing screen, since the first gradient connection structure at the beginning and end is printed using the main grid screen, its printing height is lower than that of the fine grid. Therefore, the height of all the first gradient structures in the grid electrodes can be reduced, thereby improving the problem of void soldering at the beginning and end of the solar cell.

[0049] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0050] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0051] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned. In fact, the embodiments have fewer features than all the features of the single embodiments disclosed above.

[0052] In some embodiments, numbers describing the quantity of attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples by the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the number is allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification are approximate values, which may be changed according to the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit preservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0053] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the scope of the essential spirit of this application will fall within the scope of this application.

Claims

1. A solar cell, characterized in that, include: Battery cells; Multiple fine grids; Multiple main grids, a harpoon structure connected to the two ends of each main grid, and a conductive connection point located at the connection between each main grid and the harpoon structure; A first gradient connection structure located in the target area and a second gradient connection structure located outside the target area, wherein the target area is the connection point between the target fine gate and each main gate, and the target fine gate is at least one adjacent fine gate adjacent to the conductive connection point along the center direction of the corresponding main gate; The height of the first gradient connection structure is lower than the height of the second gradient connection structure. Both the first gradient connection structure and the second gradient connection structure are used to connect the corresponding main gate and the corresponding fine gate.

2. The solar cell as described in claim 1, characterized in that, The height difference between the first gradient connection structure and the second gradient connection structure is 1-5 μm.

3. The solar cell as described in claim 1, characterized in that, The line width of the first gradient connection structure is greater than the line width of the second gradient connection structure.

4. The solar cell as described in claim 3, characterized in that, The linewidth difference between the first gradient connection structure and the second gradient connection structure is 10-40 μm.

5. The solar cell according to any one of claims 1-4, characterized in that, The height of the first gradient connection structure is 5-7 μm.

6. The solar cell according to any one of claims 1-4, characterized in that, The linewidth of the first gradient connection structure is 50-70μm.

7. The solar cell according to any one of claims 1-4, characterized in that, The height of the second gradient connection structure is 8-10 μm.

8. The solar cell according to any one of claims 1-4, characterized in that, The linewidth of the second gradient connection structure is 30-60μm.

9. The solar cell according to any one of claims 1-4, characterized in that, The number of the target fine gates is 3-10.

10. A printing screen for solar cells, characterized in that, include: The main grid screen includes multiple main grids, a harpoon structure connected to both ends of each main grid, a conductive connection point located at the connection between each main grid and the harpoon structure, and a first gradient connection structure located in a target area. The target area is the connection between a target fine grid and each main grid, and the target fine grid is at least one adjacent fine grid adjacent to the conductive connection point along the center direction of the corresponding main grid. A fine grid pattern, the fine grid pattern comprising a plurality of fine grids and a second gradient connection structure located outside the target region; Both the first gradient connection structure and the second gradient connection structure are used to connect the corresponding main gate and the corresponding fine gate.

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