Solar cell and photovoltaic module

Abstract

The utility model relates to a solar cell and a photovoltaic module. The solar cell comprises a substrate and a plurality of main grid lines arranged on a first surface and / or a second surface of the substrate, the first surface and / or the second surface are oppositely arranged, the main grid lines extend in the first direction, and the main grid lines are distributed at intervals in the second direction; a plurality of bonding pads are arranged on each main grid line at intervals in the first direction; the surface, away from the substrate, of each bonding pad is provided with two local welding spots, and the two local welding spots are distributed at intervals in the second direction. The first direction and the second direction intersect and are both perpendicular to the thickness direction of the substrate. The local welding spots are arranged on the bonding pad to form the limiting structure, so that the welding strip can be limited during assembly end welding, the deviation phenomenon of the welding strip is reduced, a welding window can be effectively improved, the contact area of the welding strip and the welding spot structure is increased, good welding tension and electrical contact are achieved, the welding yield of the welding strip is increased, assembly rework is reduced, and the production cost is reduced. The assembly yield is improved and the assembly manufacturing cost is effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to solar cells and photovoltaic modules. Background Art

[0002] As the size of solar cells continues to increase, the photovoltaic industry is accelerating its expansion and a large amount of new production capacity is released. It is extremely important to reduce manufacturing costs.

[0003] In the related technologies, in order to reduce costs and increase efficiency, the CT time of component welding machines continues to decrease. The welding window for components is getting smaller and smaller. It is particularly important to improve the welding window of solar cells under high-speed welding conditions and improve the welding yield. Utility Model Content

[0004] Based on this, it is necessary to provide a solar cell and photovoltaic module that can effectively improve the welding window, increase the welding yield, reduce module rework, and increase module output, thereby reducing the manufacturing cost of the module.

[0005] In a first aspect, an embodiment of the present application provides a solar cell, comprising:

[0006] The substrate has a first surface and a second surface disposed opposite to each other along the thickness direction of the substrate;

[0007] A plurality of main grid lines are arranged on the first surface and / or the second surface of the substrate, the main grid lines extend along a first direction, and the plurality of main grid lines are spaced apart and distributed along a second direction;

[0008] A plurality of pads, each of the main grid lines is provided with a plurality of pads spaced apart along the first direction;

[0009] A plurality of local soldering points, wherein two local soldering points are arranged on the surface of each soldering pad facing away from the substrate, and the two local soldering points are spaced apart and distributed along the second direction;

[0010] The first direction intersects with the second direction and both are perpendicular to the thickness direction.

[0011] In some embodiments, protruding microstructures are provided on the oppositely disposed inner side surfaces of the two local welding points.

[0012] In some embodiments, the protruding microstructure includes a plurality of tooth-shaped protrusions arranged along the first direction.

[0013] In some embodiments, the height of the local welding point is greater than or equal to 0.01 mm and less than or equal to 0.2 mm.

[0014] In some embodiments, outer side surfaces of the two local solder joints that are disposed opposite to each other are respectively flush with two side surfaces of the solder pad that are perpendicular to the second direction.

[0015] In some embodiments, a maximum dimension of the local solder joint along the first direction is smaller than or equal to a maximum dimension of the solder pad along the first direction.

[0016] In some embodiments, a maximum dimension of the local welding spot along the second direction is greater than or equal to 0.05 mm and less than or equal to 0.2 mm.

[0017] In some embodiments, the height of the pad is greater than or equal to 30 micrometers and less than or equal to 70 micrometers.

[0018] In some embodiments, the maximum dimension of the pad along the first direction is greater than or equal to 0.4 mm and less than or equal to 1.2 mm; and / or the maximum dimension of the pad along the second direction is greater than or equal to 0.4 mm and less than or equal to 1.2 mm.

[0019] In a second aspect, an embodiment of the present application provides a photovoltaic module, including:

[0020] A battery string, comprising a plurality of solar cells according to any one of the first aspects and a plurality of welding ribbons, wherein the welding ribbons are welded to welding pads of the plurality of solar cells and are located between two local welding points on the welding pads, and the adjacent solar cells in the battery string are electrically connected through the welding ribbons;

[0021] A front packaging film covering the front side of the battery string;

[0022] A back packaging film, covering the back of the battery string;

[0023] A front glass covering a surface of the front packaging film facing away from the battery string; and

[0024] A back plate covers the surface of the back packaging film away from the battery string.

[0025] The above-mentioned solar cell and photovoltaic module, by setting local welding points on the welding pad to form a limiting structure, can limit the welding strip when welding at the module end, reduce the welding strip deviation phenomenon, effectively improve the welding window, and increase the contact area between the welding strip and the welding point structure, so as to achieve better welding tension and electrical contact, and can also reduce the problem of solder widening to both sides, thereby ensuring the welding effect of the welding strip and the solar cell, improving the welding yield of the welding strip, reducing module rework, and increasing module production, and the preparation process is simple, which effectively reduces the module manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a front view of a solar cell according to some embodiments of the present application.

[0027] Figure 2 This is a top view of a solar cell according to some embodiments of the present application.

[0028] Figure 3 for Figure 2 Schematic diagram of the partially enlarged structure of part A in the middle.

[0029] Figure 4 sectional views of pads and local solder joints according to some embodiments of the present application.

[0030] Figure 5 Detailed top view of solder pads and local solder joints according to some embodiments of the present application.

[0031] Figure 6 It is a cross-sectional schematic diagram of welding of welding strips, welding pads and local welding points according to some embodiments of the present application.

[0032] Figure 7 It is a schematic top view of welding of welding strips, welding pads and local welding points according to some embodiments of the present application.

[0033] Figure 8 The top view of solar cells according to other embodiments of the present application.

[0034] Fig. 9 for Figure 5 Schematic diagram of the partial enlarged structure of part B in the middle.

[0035] Fig.10 This is a schematic diagram of the structure of photovoltaic modules according to some embodiments of the present application.

[0036] Figure Number:

[0037] 10. Solar cell; 1. Substrate; 11. First surface; 12. Second surface; 2. Main grid line; 3. Solder pad; 4. Local solder joint; 5. Secondary grid line; 6. Protruding microstructure; 61. Tooth-shaped protrusion; 20. Solder strip;

[0038] 1000, photovoltaic module; 100, battery string; 200, front encapsulation film; 300, back encapsulation film; 400, front glass; 500, back panel. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth 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 violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. An element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and are not intended to be the only implementation method.

[0045] As the size of solar cells continues to increase, the photovoltaic industry is accelerating its expansion and a large amount of new production capacity is released. It is extremely important to reduce manufacturing costs.

[0046] In the related technologies, in order to reduce costs and increase efficiency, the CT time of component welding machines continues to decrease. The welding window for components is getting smaller and smaller. It is particularly important to improve the welding window of solar cells under high-speed welding conditions and improve the welding yield.

[0047] See also Figures 1 to 5 , Figure 1 shows a front view of a solar cell in some embodiments of the present application, Figure 2 shows a top view of a solar cell in some embodiments of the present application, Figure 3 for Figure 2 The partial enlarged structural diagram of the middle A part, Figure 4 shows a cross-sectional view of a pad and a local solder joint in some embodiments of the present application, Figure 5 A top view of the pads and local soldering points in some embodiments of the present application is shown; the solar cell 10 provided in the embodiment of the present application includes a substrate 1, a plurality of main grid lines 2, a plurality of pads 3 and a plurality of local soldering points 4; the substrate 1 has a first surface 11 and a second surface 12 arranged opposite to each other along its thickness direction; a plurality of main grid lines 2 are arranged on the first surface 11 and / or the second surface 12 of the substrate 1, the main grid lines 2 extend along the first direction, and the plurality of main grid lines 2 are spaced apart along the second direction; a plurality of pads 3 are spaced apart along the first direction on each main grid line 2; two local soldering points 4 are arranged on the surface of each pad 3 facing away from the substrate 1, and the two local soldering points 4 are spaced apart along the second direction; wherein the first direction intersects with the second direction and is perpendicular to the thickness direction of the substrate 1.

[0048] like Figures 1 to 5 As shown in , the X direction is the first direction, the Y direction is the second direction, and the Z direction is the thickness direction of the substrate 1 .

[0049] Specifically in some embodiments, the first direction and the second direction are perpendicular to each other, the first direction is the length direction of the solar cell 10 , and the second direction is the width direction of the solar cell 10 .

[0050] The substrate 1 may be a P-type or N-type solar cell silicon substrate; the substrate 1 absorbs sunlight and directly converts solar radiation energy into electrical energy using the photovoltaic effect, and generates current on the surface of the substrate 1. For example, the solar cell may be a PERC (Passivated Emitter and Rear Cell), a TOPCon (Thin Oxide Passivated Contact cell), a HJT (Heterojunction Technology), an IBC (Interdigitated back contact) or a perovskite cell, etc., which are not limited here. The first surface 11 of the substrate 1 may be the front surface of the substrate 1, that is, the surface of the substrate 1 facing the sunlight; the second surface 12 of the substrate 1 may be the back surface of the substrate 1, that is, the surface of the substrate 1 facing away from the sunlight. It can be understood that the front surface of the substrate 1 is usually the light-receiving surface, which can receive sunlight directly incident on the substrate 1, and the back surface of the substrate 1 corresponds to the backlight surface, which can receive scattered and refracted sunlight.

[0051] The main grid line 2 is the grid line electrode of the solar cell 10, which is used to collect the current on the surface of the substrate 1 for convergence output. A plurality of main grid lines 2 are arranged on the first surface 11 and / or the second surface 12 of the substrate 1. Taking the solar cell 10 for double-sided power generation as an example, the main grid lines 2 are arranged on the first surface 11 and the second surface 12 of the substrate 1, and the number of the main grid lines 2 on each side is multiple, and the plurality of main grid lines 2 are spaced apart along the second direction, for example, the number of the main grid lines 2 on each side is 6-20, and for example, the first surface 11 of the substrate 1 can be provided with 10 main grid lines 2, 12 main grid lines 2, 16 main grid lines 2, 18 main grid lines 2 or 20 main grid lines 2. It can be understood that the number of the main grid lines 2 arranged on the first surface 11 of the substrate 1 can be the same as the number of the main grid lines 2 arranged on the second surface 12 of the substrate 1, or can be different, and is not limited here. For example, in some specific embodiments, the number of busbars 2 disposed on the first surface 11 of the substrate 1 is the same as the number of busbars 2 disposed on the second surface 12 of the substrate 1, and the structures and arrangements are the same. It should be noted that the same structures and arrangements of the busbars 2 located on the first surface 11 and the second surface 12 means that the busbars 2 on the first surface 11 of the substrate 1 and the busbars 2 on the second surface 12 of the substrate 1 maintain position correspondence and overlap of orthographic projections in the thickness direction of the substrate 1. Of course, in some other embodiments, the orthographic projections of the busbars 2 on the first surface 11 of the substrate 1 and the busbars 2 on the second surface 12 of the substrate 1 in the thickness direction of the substrate 1 may also partially overlap or be staggered.

[0052] The main grid line 2 extends along a first direction, and a plurality of pads 3 are arranged on the main grid line 2 at intervals along the first direction. For example, the number of pads 3 corresponding to each main grid line 2 may be 4-10. For example, the number of pads 3 corresponding to each main grid line 2 arranged on the first surface 11 of the substrate 1 may be 4, 5, 6, 7, 8, 9 or 10, and the number of pads 3 corresponding to each main grid line 2 arranged on the second surface 12 of the substrate 1 may be 4, 5, 7, 9 or 10. The orthographic projection contour shape of the pad 3 on the substrate 1 may be a polygon, a circle or an ellipse, which is not limited here. For example, the orthographic projection contour shape of the pad 3 on the substrate 1 may be a rectangle, one contour edge of the pad 3 is parallel to the first direction, another contour edge of the pad 3 is parallel to the second direction, and two adjacent contour edges are perpendicular to each other to form a right angle. The width of the main grid line 2 along the second direction is relatively small, usually much smaller than the width of the welding strip used to connect the solar cell 10 at the component end. For example, the diameter of the circular welding strip is about 300 microns, while the width of the main grid line 2 is usually less than 100 microns. By setting a welding pad 3 on the main grid line 2, the width of the welding pad 3 is larger than the width of the main grid line 2, and the solar cell 10 at the component end is welded to the welding strip through the welding pad 3, avoiding the problem of poor welding effect and welding strip deviation during the actual welding process due to the small width of the main grid line 2 when directly welding the main grid line 2 to the welding strip, thereby ensuring the welding accuracy and welding tension when welding the solar cell 10 to the welding strip.

[0053] Furthermore, each pad 3 is provided with two local solder joints 4 on the surface facing away from the substrate 1, and the two local solder joints 4 are spaced apart along the second direction. The two local solder joints 4 are protruding from the surface of the pad 3 to form a height difference, thereby forming a limit groove structure between the two local solder joints 4, and the pad 3 and the local solder joints 4 form a two-layer solder joint structure; the orthographic projection contour shape of the local solder joint 4 on the pad 3 can be polygonal, circular or elliptical, which is not limited here. Figure 6 and Figure 7 , Figure 6 A cross-sectional view of welding of a welding strip, a welding pad and a local welding spot in some embodiments of the present application is shown. Figure 7 The top view of the welding of the welding ribbon, the welding pad and the local welding point in some embodiments of the present application is shown. When the welding ribbon 20 at the component end is welded, the welding ribbon 20 can be limited between the two local welding points 4. The position of the welding ribbon 20 is limited and fixed by the limiting groove structure, so as to reduce the displacement of the welding ribbon 20. The welding ribbon 20 is not easy to deviate from the welding pad 3, so as to avoid welding deviation when the welding ribbon 20 is welded to the welding pad 3, and increase the contact area between the welding ribbon 20 and the welding point structure, so as to achieve better welding tension and electrical contact, and also reduce the problem of solder widening to both sides, so as to ensure the welding effect of the welding ribbon 20 and the solar cell 10, and avoid welding abnormalities that lead to reduced performance of the prepared photovoltaic module.

[0054] In addition, combined Figure 8 , Figure 8 The top view of the solar cell in some other embodiments of the present application is shown. In some embodiments, the solar cell 10 further includes a plurality of secondary grid lines 5, which are arranged on the first surface 11 and / or the second surface 12 of the substrate 1, and the secondary grid lines 5 extend along the second direction, and the plurality of secondary grid lines 5 are spaced apart along the first direction. The grid line electrodes on the front and / or back of the substrate 1 of the solar cell 10 include intersecting (usually mutually perpendicular) main grid lines 2 and secondary grid lines 5, wherein the secondary grid lines 5 are used to guide current, and the main grid lines 2 are used to collect current on the secondary grid lines 5 for convergence.

[0055] The main grid line 2, the pad 3, the local solder joint 4 and the auxiliary grid line 5 can be printed on the substrate 1 using a metal paste to form a desired metallization pattern, and then prepared by sintering. For example, the metal paste used for printing can be a silver-aluminum paste, a silver paste or an aluminum paste, which is not limited here. Screen printing can be performed using a screen. Since the pad 3 and the local solder joint 4 form a two-layer solder joint structure, when preparing the solar cell 10, the pad 3 and the local solder joint 4 can be printed twice; for example, the printing process of the solar cell 10 can be: first print the main grid line 2 on the substrate 1, and then print the pad 3 on the main grid line 2 at the same time; then print the auxiliary grid line 5, and then print the local solder joint 4 on the pad 3 at the same time. In this way, the height difference can be established by using the local solder joint 4 formed when printing the auxiliary grid line 5, without updating the preparation process, which is simple and convenient, and reduces costs.

[0056] The solar cell 10 of the embodiment of the present application forms a limiting structure by setting a local welding point 4 on the welding pad 3, which can limit the welding ribbon 20 when welding at the component end, reduce the deviation of the welding ribbon 20, effectively improve the welding window, and increase the contact area between the welding ribbon 20 and the welding point structure, so as to achieve better welding tension and electrical contact, and can also reduce the problem of solder widening to both sides, thereby ensuring the welding effect of the welding ribbon 20 and the solar cell 10, improving the welding yield of the welding ribbon 20, reducing component rework, and increasing component production. In addition, the preparation process is simple, which effectively reduces the component manufacturing cost.

[0057] In some embodiments, see Figures 3 to 5 , and see further Fig. 9 , Fig. 9 Shows Figure 5 A schematic diagram of the partial enlarged structure of the middle B portion; protruding microstructures 6 are provided on the inner side surfaces of the two local welding points 4 which are arranged opposite to each other.

[0058] The inner side surface of the local welding spot 4 refers to the side surface facing the middle of the two local welding spots 4, and the inner side surfaces of the two local welding spots 4 are arranged opposite to each other along the second direction; since the welding strip 20 is limited between the two local welding spots 4 during welding, the inner side surface of the local welding spot 4 faces the welding strip 20 during welding. The protruding microstructure 6 refers to a structure composed of a plurality of micro protrusions formed on the inner side surface of the local welding spot 4 along the second direction, and the shape of the micro protrusions can be spherical, cylindrical, and other shapes, which are not limited here.

[0059] By processing the inner side surface of the local solder joint 4 into a raised microstructure 6 during printing, the raised microstructure 6 can increase the friction between the solder strip 20 and the local solder joint 4 when the solder strip 20 is welded, thereby improving the limiting effect on the solder strip 20 and further reducing the deviation of the solder strip 20. In addition, the raised microstructure 6 can increase the contact area between the local solder joint 4 and the solder strip 20, thereby improving the welding strength, improving the flux effect of welding the solar cell 10 and the solder strip 20, and improving the welding yield.

[0060] In some embodiments, see Fig. 9 The protruding microstructure 6 includes a plurality of tooth-shaped protrusions 61 arranged along a first direction.

[0061] A plurality of tooth-like protrusions 61 form a sawtooth protrusion microstructure 6, which can further increase the friction between the local solder joint 4 and the soldering ribbon 20, better limit the active area of ​​the soldering ribbon 20, further improve the flux effect of the soldering between the solar cell 10 and the soldering ribbon 20, and improve the soldering yield.

[0062] In some embodiments, see Figure 4 , a height H1 of the local welding point 4 is greater than or equal to 0.01 mm and less than or equal to 0.2 mm.

[0063] The height H1 of the local solder joint 4 refers to the distance between the surface of the solder pad 3 facing away from the substrate 1 and the surface of the local solder joint 4 facing away from the solder pad 3 along the thickness direction (Z direction) of the substrate 1. The height H1 of the local solder joint 4 is set to be greater than or equal to 0.01 mm and less than or equal to 0.2 mm. For example, the height H1 of the local solder joint 4 can be 0.01 mm, 0.05 mm, 0.1 mm, 0.15 mm or 0.2 mm; specifically, it can be matched with the diameter of the solder strip 20 used in actual welding. For example, the diameter of the solder strip 20 is generally 0.1 mm to 0.5 mm. Figure 6 As shown in the figure, the local solder joint 4 utilizes the height difference with the solder pad 3 to achieve the position limitation of the solder strip 20. It can be understood that the higher the height H1 of the local solder joint 4, the better the limiting effect of the solder strip 20; however, if the height of the local solder joint 4 is too high, it will cause interference when the solder strip 20 is placed between two local solder joints 4, and will also cause an increase in the consumption of printing paste.

[0064] By setting the height H1 of the local welding point 4 within the above-mentioned size range, it is beneficial to facilitate the welding operation while taking into account the limiting effect of the welding strip 20, and it can also save printing paste and reduce costs.

[0065] In some embodiments, see Figure 4 and Figure 5 The outer side surfaces of the two local welding points 4 which are arranged opposite to each other are respectively flush with the two side surfaces of the welding pad 3 which are perpendicular to the second direction.

[0066] The outer side surface of the local solder joint 4 refers to the side surface away from the middle of the two local solder joints 4; the two side surfaces of the pad 3 perpendicular to the second direction belong to the outer side surfaces of the pad 3 perpendicular to the surface of the substrate 1; the outer side surfaces of the two local solder joints 4 arranged opposite to each other are respectively flush with the two side surfaces of the pad 3 perpendicular to the second direction, so that the local solder joint 4 is located within the size range of the pad 3 at least along the second direction.

[0067] Such an arrangement can avoid the local solder joint 4 from being too large in size and thus increasing the shading area of ​​the solder joint structure, thereby reducing the impact on the power generation performance of the solar cell 10 , and at the same time can save printing paste and reduce costs.

[0068] In some embodiments, see Figure 4 , the maximum dimension W1 of the local welding point 4 along the second direction is greater than or equal to 0.05 mm and less than or equal to 0.2 mm.

[0069] For example, the maximum dimension W1 of the local solder joint 4 along the second direction can be 0.05 mm, 0.1 mm, 0.15 mm or 0.2 mm, which can be specifically matched with the width of the soldering pad 3 and the diameter of the soldering strip 20 used in actual welding. It can be understood that the maximum dimension W1 of the local solder joint 4 along the second direction and the width of the soldering pad 3 jointly define the minimum distance dimension between the two local solder joints 4, and the soldering strip 20 is limited between the two local solder joints 4, so the minimum distance between the two local solder joints 4 is greater than the diameter of the soldering strip 20.

[0070] By setting the maximum size W1 of the local solder joint 4 along the second direction within the above-mentioned size range, it is beneficial to reduce the size of the local solder joint 4 and the solder pad 3 while taking into account the limiting effect of the solder strip 20, thereby saving printing paste, reducing costs, and avoiding the shading area being too large to affect the power generation performance of the solar cell 10.

[0071] In some embodiments, see Figure 4 , a height H2 of the pad 3 is greater than or equal to 30 micrometers and less than or equal to 70 micrometers.

[0072] The height H2 of the pad 3 refers to the distance between the surface of the pad 3 facing away from the substrate 1 and the surface of the substrate 1 along the thickness direction (Z direction) of the substrate 1. For example, the height H2 of the pad 3 can be 30 microns, 40 microns, 50 microns, 60 microns or 70 microns; the height H2 of the pad 3 can specifically match the height of the main grid line 2, for example, the height H2 of the pad 3 is equal to the height of the main grid line 2.

[0073] By setting the height H2 of the local pad 3 within the above-mentioned size range, printing paste can be saved, which is beneficial for taking into account the cost while having good welding reliability and conductive performance.

[0074] In some embodiments, see Figure 5 , the maximum dimension L1 of the local solder joint 4 along the first direction is less than or equal to the maximum dimension L2 of the solder pad 3 along the first direction.

[0075] Such arrangement enables at least the local solder joint 4 to be located within the size range of the solder pad 3 along the first direction, thereby avoiding the local solder joint 4 being too large in size and increasing the shading area of ​​the solder joint structure, reducing the impact on the power generation performance of the solar cell 10, and saving printing paste and reducing costs.

[0076] In some embodiments, see Figure 4 , the maximum dimension W2 of the pad 3 along the second direction is greater than or equal to 0.4 mm and less than or equal to 1.2 mm. Figure 5 , a maximum dimension L2 of the pad 3 along the first direction is greater than or equal to 0.4 mm and less than or equal to 1.2 mm.

[0077] For example, the maximum dimension W2 of the pad 3 along the second direction can be 0.4 mm, 0.6 mm, 0.8 mm, 1 mm or 1.2 mm, and the maximum dimension L2 of the pad 3 along the first direction can be 0.4 mm, 0.5 mm, 0.7 mm, 0.9 mm or 1.2 mm; it can be understood that the maximum dimension L2 of the pad 3 along the first direction and the maximum dimension W2 of the pad 3 along the second direction jointly define the area size of the pad 3, and the area size of the pad 3 affects the welding accuracy and welding tension of the solder strip 20 and the pad 3, as well as affects the printing paste consumption and shading area size of the pad 3.

[0078] By setting the maximum dimension W2 of the pad 3 along the second direction and the maximum dimension L2 along the first direction within the above-mentioned dimension range, it is beneficial to reduce the area of ​​the pad 3 while taking into account the welding reliability, thereby reducing the shading area of ​​the pad 3, avoiding the shading area being too large to affect the power generation performance of the solar cell 10, saving printing paste and reducing costs.

[0079] Based on the same inventive concept, see Fig.10 , Fig.10 A schematic diagram of the structure of a photovoltaic module in some embodiments of the present application is shown. The embodiment of the present application also provides a photovoltaic module 1000, which includes a battery string 100, a front packaging film 200, a back packaging film 300, a front glass 400 and a back plate 500. The battery string 100 includes a plurality of solar cells 10 provided by any of the above embodiments and a plurality of welding ribbons 20; the welding ribbons 20 are welded to the welding pads 3 of the plurality of solar cells 10 and are located between two local welding points 4 on the welding pads 3, and adjacent solar cells 10 in the battery string 100 are electrically connected through the welding ribbons 20; the front packaging film 200 covers the front side of the battery string 100, and the back packaging film 300 covers the back side of the battery string 100; the front glass 400 covers the surface of the front packaging film 200 facing away from the battery string 100; the back plate 500 covers the surface of the back packaging film 300 facing away from the battery string 100.

[0080] like Fig.10 As shown in , the Z direction is the thickness direction of the photovoltaic component 1000 .

[0081] The thickness direction of the photovoltaic module 1000 is parallel to the thickness direction of the substrate 1 of the solar cell 10. The front glass 400, the front packaging film 200, the battery string 100, the back packaging film 300 and the back plate 500 are stacked in sequence along the thickness direction of the photovoltaic module 1000; the front side of the photovoltaic module 1000 is the side surface of the photovoltaic module 1000 facing the sunlight, and the back side of the photovoltaic module 1000 is the side surface of the photovoltaic module 1000 facing away from the sunlight. The battery string 100 can be one or more; if there are more than one battery string 100, the multiple battery strings 100 can be connected in series, in parallel or in mixed connection. Mixed connection means that the multiple battery strings 100 are both connected in series and in parallel, which can provide higher voltage and capacity; each battery string 100 includes multiple solar cells 10 connected in series through a welding ribbon 20, one end of the bus bar is connected to the solar cell string 100, and the other end is connected to the junction box, so as to lead the electric energy generated by the photovoltaic module 1000 to the external load through the junction box; the cross-sectional shape of the welding ribbon 20 can be circular, rectangular or other shapes, which are not limited here. The front glass 400 can be a photovoltaic glass with a high light transmittance (a light transmittance of more than 92%), such as double-coated glass; the back plate 500 can be a transparent or opaque plate; the front glass 400 and the back plate 500 protect the internal packaging materials and the solar cells 10 from mechanical damage and external environmental erosion, and are waterproof and insulated. The front encapsulation film 200 and the back encapsulation film 300 can be ethylene-vinyl acetate copolymer (EVA) film, polyolefin elastomer (POE) film or polyvinyl butyral film (PVB) film, etc. The front encapsulation film 200 and the back encapsulation film 300 are used to encapsulate and protect the solar cell 10 to prevent the external environment from affecting the performance of the solar cell 10. At the same time, the front encapsulation film 200 bonds the front glass 400 and the solar cell 10 together, and the back encapsulation film 300 bonds the back plate 500 and the solar cell 10 together, and have a certain bonding strength.

[0082] The photovoltaic module 1000 connects single solar cells in series and parallel, packages them, and connects external wires to become a solar cell module that can be used independently as a photovoltaic power source; the solar cell module absorbs sunlight and uses the photovoltaic effect to directly convert solar radiation energy into the electrical energy output required by the user.

[0083] Since the photovoltaic assembly 1000 has the same beneficial effects as the solar cell 10 of the above embodiment, they will not be described in detail here.

[0084] The photovoltaic assembly 1000 disclosed in the embodiment of the present application can be applied to, but not limited to, photovoltaic power generation systems such as solar power stations, and can also be applied to electrical equipment such as electric vehicles, ships or aircraft to form a power supply system for the electrical equipment.

[0085] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A solar cell, characterized in that: include: The substrate has a first surface and a second surface disposed opposite to each other along the thickness direction of the substrate; A plurality of main grid lines are arranged on the first surface and / or the second surface of the substrate, the main grid lines extend along a first direction, and the plurality of main grid lines are spaced apart and distributed along a second direction; A plurality of pads, each of the main grid lines is provided with a plurality of pads spaced apart along the first direction; A plurality of local soldering points, wherein two local soldering points are arranged on the surface of each soldering pad facing away from the substrate, and the two local soldering points are spaced apart and distributed along the second direction; The first direction intersects with the second direction and both are perpendicular to the thickness direction.

2. The solar cell according to claim 1, characterized in that: The inner side surfaces of the two local welding points that are arranged opposite to each other are provided with protruding microstructures.

3. The solar cell according to claim 2, characterized in that: The protrusion microstructure includes a plurality of tooth-shaped protrusions arranged along the first direction.

4. The solar cell according to claim 1, characterized in that: The height of the local welding point is greater than or equal to 0.01 mm and less than or equal to 0.2 mm.

5. The solar cell according to claim 1, characterized in that: The outer side surfaces of the two local welding points which are arranged opposite to each other are respectively flush with the two side surfaces of the welding pad which are perpendicular to the second direction.

6. The solar cell according to claim 1, characterized in that: A maximum dimension of the local solder joint along the first direction is smaller than or equal to a maximum dimension of the solder pad along the first direction.

7. The solar cell according to claim 1, characterized in that: A maximum dimension of the local welding spot along the second direction is greater than or equal to 0.05 mm and less than or equal to 0.2 mm.

8. The solar cell according to claim 1, characterized in that: The height of the pad is greater than or equal to 30 micrometers and less than or equal to 70 micrometers.

9. The solar cell according to claim 1, characterized in that: The maximum dimension of the pad along the first direction is greater than or equal to 0.4 mm and less than or equal to 1.2 mm; And / or, the maximum dimension of the pad along the second direction is greater than or equal to 0.4 mm and less than or equal to 1.2 mm.

10. A photovoltaic module, characterized in that: include: A battery string, comprising a plurality of solar cells according to any one of claims 1 to 9 and a plurality of welding ribbons, wherein the welding ribbons are welded to welding pads of the plurality of solar cells and are located between two local welding points on the welding pads, and the adjacent solar cells in the battery string are electrically connected through the welding ribbons; A front packaging film covering the front side of the battery string; A back packaging film, covering the back of the battery string; A front glass covering a surface of the front packaging film facing away from the battery string; as well as A back plate covers the surface of the back packaging film away from the battery string.

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