Solar cell, solar cell module and photovoltaic system

Abstract

The utility model relates to the technical field of solar cells, and discloses a solar cell, a solar cell module and a photovoltaic system, the cell comprises a plurality of cell sheets, the front surfaces of the cell sheets are provided with grid lines; the welding strip is used for connecting the battery pieces and arranging the battery pieces in sequence; the welding strip is arranged on the grid line, the bonding pad is arranged on the grid line, the welding strip is connected with the bonding pad, the bonding pad is composed of a plurality of bonding pad units, and the plurality of bonding pad units are connected through conductive wires. According to the utility model, more welding points can be provided, the contact area between the welding pad and the welding strip can be increased, the mechanical strength of the welding points can be improved, the consistency and reliability of welding can be improved, the wet weight of silver paste can be reduced, and the cost can be reduced; therefore, the photo-generated current collected by the grid line can be smoothly conducted to the welding strip through the bonding pad, and the signal transmission quality is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a solar cell, a solar cell assembly and a photovoltaic system. Background Art

[0002] As a green and renewable energy source, solar energy has many advantages, including being inexhaustible, clean and environmentally friendly. Solar cells, known in physics as solar photovoltaics or simply photovoltaics, can directly convert sunlight into electrical energy, with the core component being the cell. The cell consists of a silicon substrate, grid lines printed on the silicon substrate, and solder pads. The solder pads are used to solder to the solder ribbons. The cell collects the photocurrent generated by the silicon substrate through the grid lines and transmits it to the solder ribbons through the solder pads. The solder ribbons firmly connect the cells together through welding, and are responsible for collecting the current generated by the cell and transmitting it to the outside of the cell to generate electricity. Therefore, the reliability of the soldering of the solder pads and solder ribbons directly affects the performance of the photovoltaic cell.

[0003] In the prior art, the soldering area of ​​the pads is generally increased by enlarging the pad size or increasing the number of pads. This increases the soldering interface area between the pad and the ribbon, thereby improving the soldering reliability of the pad and ribbon. However, during the pad printing process, increasing the pad size or the number of pads will lead to an increase in the amount of printing paste used, resulting in increased manufacturing costs for photovoltaic cells. It will also increase the obstruction of the cell surface, thereby increasing the light-receiving area. Utility Model Content

[0004] The technical problem to be solved by the present invention is to provide a solar cell, a solar cell module and a photovoltaic system, which can reduce the material usage of the pad and reduce the manufacturing cost of the solar cell, while increasing the welding strength between the soldering ribbon and the pad and improving the performance stability of the solar cell.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a solar cell, comprising:

[0006] A plurality of battery cells, each having a grid line disposed on its front surface;

[0007] Welding strips for connecting the battery cells and arranging them in sequence;

[0008] The pad is arranged on the gate line, the soldering strip is connected to the pad, the pad is composed of a plurality of pad units, and the plurality of pad units are connected by conductive lines.

[0009] As an improvement to the above solution, the ratio of the width of the soldering strip to the width of the soldering pad unit is 1:(0.25-0.5).

[0010] As an improvement of the above solution, the width of the pad unit is 0.1mm to 0.5mm;

[0011] The distance between adjacent pad units is 0.1 mm to 0.5 mm.

[0012] As an improvement to the above solution, the cross-sectional shape of the welding strip is one of circular and elliptical.

[0013] As an improvement to the above solution, a surface of the pad unit in contact with the soldering strip has a micro-concave-convex structure.

[0014] As an improvement to the above solution, a surface of the pad unit in contact with the soldering strip has a uniformly distributed micro-concave-convex structure.

[0015] As an improvement to the above solution, the micro concave-convex structure is formed by dispersed pits.

[0016] As an improvement to the above solution, the ratio of the depth of the pit to the height of the pad is 1:(5-20).

[0017] As an improvement of the above solution, the depth of the pit is 0.01 mm to 0.1 mm, and the width of the pit is 0.05 mm to 0.1 mm.

[0018] As an improvement to the above solution, the shape of the pit is pyramidal.

[0019] As an improvement to the above solution, the shape of the pits is one or more of a cube, a prism, a cuboid, and a cylinder, and the pits are arranged at intervals on the pad unit.

[0020] As an improvement to the above solution, the pit is a printed structure formed by metal material on the surface of the pad unit.

[0021] As an improvement of the above solution, the metal material is one of copper, solder paste, aluminum, and silver.

[0022] As an improvement to the above solution, the cross-sectional shape of the pad is rectangular, and the cross-sectional shape of the pad unit is one or more of rectangular, square, and circular.

[0023] As an improvement to the above solution, the material of the conductive wire is one of solder paste, conductive glue, copper, aluminum, and silver.

[0024] A second aspect of the present invention provides a solar cell assembly, comprising the solar cell.

[0025] A second aspect of the present invention provides a photovoltaic system, comprising the aforementioned solar cell assembly.

[0026] The implementation of this utility model has the following beneficial effects:

[0027] (1) In the present invention, the pad unit can provide more welding points, thereby increasing the number and distribution uniformity of the welding points, thereby increasing the contact area between the pad and the welding strip, and helping to improve the mechanical strength of the welding point, reducing the breakage of the welding point caused by external force or vibration, and improving the reliability of the solar cell.

[0028] (2) In the present invention, the soldering pad is composed of a plurality of soldering pad units, which is equivalent to reducing the area of ​​the soldering pad and reducing the heat conduction during the welding process to a certain extent, thereby reducing the thermal impact on the battery cell during the soldering process of the solder strip and avoiding damage to the performance of the battery cell. In addition, the setting of the soldering pad unit helps to more accurately control the welding temperature and time, thereby improving the consistency and reliability of welding.

[0029] (3) In the present invention, the solder pad is composed of a plurality of solder pad units, which reduces the contact area between the solder pad and the cell, increases the light-receiving area of ​​the cell, reduces the amount of paste used in printing the solder strip, reduces the wet weight of the silver paste, and thus reduces the cost. Furthermore, the plurality of solder pad units are connected by conductive wires, which ensures that the photocurrent collected by the gate line is smoothly conducted to the solder strip through the solder pad, thereby improving the signal transmission quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 : A schematic structural diagram of a solar cell in the present invention;

[0031] Figure 2 : A schematic structural diagram of the welding pad in the present invention;

[0032] Figure 3 : A schematic structural diagram of the side of the solder pad unit in contact with the solder strip in the present invention;

[0033] Figure 4 : A schematic structural diagram of the micro-concave-convex structure in the present invention.

[0034] Reference numerals:

[0035] 1-cell; 2-gate line; 3-solder ribbon; 4-solder pad; 41-solder pad unit; 42-conductive line; 5-micro-concave-convex structure; 51-pit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail with reference to specific embodiments below.

[0037] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

[0038] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "back", "front", "length", "width", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0039] In the description of this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0041] In the description of the present application, the disclosure below provides many different embodiments or examples for realizing the different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use scenarios of other materials.

[0042] In the description of this application, references to "embodiments" or "implementations" herein mean that the specific features, components, or characteristics described in conjunction with the embodiments or implementations may be included in at least one embodiment of the present application. The appearance of such phrases in various places in the specification does not necessarily refer to the same embodiment, nor do they refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0043] In order to solve the above problems, the first aspect of the present invention provides a solar cell, such as Figure 1 As shown, including:

[0044] A plurality of battery cells 1, each having a grid line 2 disposed on its front surface;

[0045] Welding strips 3 for connecting the battery cells 1 and arranging them in sequence;

[0046] A pad 4 is provided on the gate line 2, and the soldering tape 3 is connected to the pad 4;

[0047] like Figure 2 As shown, the pad 4 is composed of a plurality of pad units 41 , and the plurality of pad units 41 are connected by conductive wires 42 .

[0048] In the present invention, the pad 4 is composed of a plurality of pad units 41. On the one hand, the pad unit 41 can provide more welding points, thereby increasing the number and distribution uniformity of the welding points, thereby increasing the contact area between the pad 4 and the welding ribbon 3, and helping to improve the mechanical strength of the welding point, reduce the breakage of the welding point caused by external force or vibration, and improve the reliability of the solar cell.

[0049] On the other hand, the pad 4 is composed of a plurality of pad units 41, which is equivalent to reducing the area of ​​the pad 4, reducing the heat conduction during the welding process to a certain extent, thereby reducing the thermal impact of the soldering strip 3 on the battery cell 1 during the welding process, avoiding damage to the performance of the battery cell 1, and the setting of the pad unit 41 helps to more accurately control the welding temperature and time, thereby improving the consistency and reliability of welding.

[0050] In addition, the pad 4 is composed of a plurality of pad units 41, which reduces the contact area between the pad 4 and the cell 1, increases the light-receiving area of ​​the cell 1, and reduces the use of paste when printing the soldering tape 3, thereby reducing the wet weight of the silver paste and thus reducing the cost. The plurality of pad units 41 are connected by conductive wires 42, which can ensure that the photocurrent collected by the gate line 2 is smoothly transmitted to the soldering tape 3 through the pad 4, thereby improving the signal transmission quality.

[0051] In some embodiments, a fine grid is provided on the front of the cell 1, the fine grid is provided along a first direction, and the welding ribbon 3 is provided along a second direction to connect and arrange several of the cell 1, wherein the first direction is different from the second direction. It can be understood that in this case, the cell 1 is a cell 1 without a main grid, that is, a fine grid is provided on the cell 1 but no main grid is provided, and the welding ribbon 3 is directly provided on the electrode area of ​​the original main grid, and the current on the fine grid is directly collected and conducted through the electrical connection between the welding ribbon 3 and the fine grid. In this way, the more the welding ribbon 3 is attached to the cell 1, the more fine grids it can connect to, thereby conducting more current. The less the welding ribbon 3 is attached to the cell 1, the less it can connect to the fine grid, thereby conducting less current.

[0052] In some embodiments, a fine grid and a main grid are provided on the battery cell 1, the main grid and the welding strip 3 extend along the second direction, the fine grid extends along the first direction, each main grid intersects with multiple fine grids, and the welding strip 3 can be located on the main grid.

[0053] As can be understood, the soldering ribbon 3 is used to connect a plurality of cells 1 and arrange them in sequence to form a solar cell string. The soldering ribbon 3 can be provided on the light-receiving surface of the cell 1. However, the provision of the soldering ribbon 3 will reduce the light-receiving area of ​​the cell 1. Moreover, the soldering ribbon 3 is generally in the shape of an elongated strip. This increases the contact area with the soldering ribbon 3 and improves the welding effect, but also has a greater impact on the light-receiving area.

[0054] Preferably, the cross-sectional shape of the soldering ribbon 3 is circular or elliptical. Compared to conventional rectangular soldering ribbons 3, the contact area between the soldering ribbon 3 and the soldering pad 4 is smaller, which can easily lead to loose solder joints, resulting in a cold solder joint. This can make the connection between the soldering ribbon 3 and the solar cell 1 unstable, affecting the power output and reliability of the solar cell. In the present application, the soldering pad 4 is composed of a plurality of soldering pad units 41. While reducing the light shielding area, it can increase the soldering strength between the soldering ribbon 3 and the circular or elliptical soldering ribbon 3, while also reducing the amount of silver paste used in the soldering ribbon 3.

[0055] Preferably, the width of the pad unit 41 is W1, and the width of the soldering ribbon 3 is W2. By controlling the width W2 of the soldering ribbon 3 and the width W1 of the pad unit 41, the number of pad units 41 in each corresponding soldering pad 4 on each soldering ribbon 3 can be reasonably adjusted, ensuring that the soldering ribbon 3 can fully contact the soldering pad 4, smoothly transmitting current and achieving high reliability, while also preventing the provision of unused soldering pads 4 and thus unnecessary cost expenditure. More preferably, the ratio of the width W2 of the soldering ribbon 3 to the width W1 of the pad unit 41 is 1:(0.25-0.5). This ensures high soldering strength between the soldering ribbon 3 and the soldering pad 4. During the soldering process, the melted solder material can also rise outward along the conductive wire 42 or the soldering pad 4 and form a certain height. This not only further increases the contact area between the solder joint and the conductive wire, but also helps shorten the distance between the conductive wire or the soldering pad 4, reducing the path length of the current flow, thereby reducing the impedance of the circuit and effectively improving the photoelectric conversion performance of the solar cell. For example, the ratio of the width W2 of the soldering ribbon 3 to the width W1 of the soldering pad unit 41 is 1:0.25, 1:0.275, 1:0.3, 1:0.325, 1:0.35, 1:0.375, 1:0.4, 1:0.425, 1:0.45, 1:0.475, or 1:0.5, but is not limited thereto. It is understood that the soldering material here may be a small portion of melted tin in the soldering ribbon 3.

[0056] Optionally, the width W1 of the pad unit 41 is 0.1 mm to 0.5 mm, and the width W1 of the pad unit 41 is exemplarily 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, and 0.5 mm, but is not limited thereto. The width W2 of the soldering ribbon 3 is 0.4 mm to 2 mm, and the width W2 of the soldering ribbon 3 is exemplarily 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, and 2 mm, but is not limited thereto.

[0057] Furthermore, the spacing between adjacent pad units 41 is W3, and W3 is 0.1mm to 0.5mm. On the basis of the ratio of the width W1 of the solder ribbon 3 to the width W2 of the solder pad unit 41 being 1:(0.25-0.5), limiting the spacing W3 between adjacent pad units 41 to 0.1mm to 0.5mm can, to a certain extent, control the extent to which the soldering material climbs outward along the conductive wire 42 or the solder pad 4 during the soldering process, so that it is evenly distributed on the conductive wire 42 and the solder pad 4, and promotes a more secure connection between the solder ribbon 3 and the solder pad 4. If the spacing W3 between adjacent pad units 41 is too large, the soldering material climbing phenomenon will not be obvious, and the effect of improving the welding effect will be weak. However, if the spacing W3 between adjacent pad units 41 is too small, the soldering material will climb significantly, causing the surface of the solder pad 4 to be concave, which will directly lead to welding defects and reduce the product quality of the solar cell. Illustratively, the interval W3 between adjacent pad units 41 is 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, or 0.5 mm, but is not limited thereto.

[0058] Optionally, the soldering strip 3 is one of tin-plated copper soldering strip and tin-lead alloy copper soldering strip, and the material of the soldering pad 4 is silver paste. The cross-sectional shape of the soldering pad 4 is rectangular, and the cross-sectional shape of the soldering pad unit 41 is one or more of rectangular, square, and circular, which are not specifically limited in this application.

[0059] In the present invention, the conductive wire 42 serves to connect the circuits in adjacent pad units 41, thereby better connecting them to the solder ribbon 3 and conducting current to the outside. Therefore, the conductive wire 42 can be made of any conductive material. Optionally, the conductive wire 42 is made of one of solder paste, conductive adhesive, copper, aluminum, and silver, which facilitates the electrical connection between adjacent pad units 41 and facilitates the tin material on the solder ribbon 3 to climb onto the pad 4.

[0060] Preferably, if Figure 3 As shown, the side of the pad unit 41 that contacts the solder ribbon 3 has a micro-concave-convex structure 5. The provision of the micro-concave-convex structure 5 increases the roughness of the surface of the pad 4. On the one hand, it can further increase the area of ​​the pad 4 used for soldering, so that the soldering interface area between the pad 4 and the solder ribbon 3 is increased. On the other hand, it can improve the fluidity of the solder, reduce bubbles and voids during the soldering process, thereby reducing soldering defects and improving soldering quality. In addition, the provision of the micro-concave-convex structure 5 is conducive to reducing the amount of printing paste used, which can improve the soldering reliability of the pad 4 and the solder ribbon 3 while further reducing the manufacturing cost of the solar cell.

[0061] Furthermore, the side of the pad unit 41 that contacts the solder ribbon 3 has a uniformly distributed micro-concave-convex structure 5. The uniform distribution of the micro-concave-convex structure 5 can promote the uniform distribution of the soldering points between the solder ribbon 3 and the pad 4, thereby increasing the soldering strength between the solder ribbon 3 and the pad 4. It is understandable that the micro-concave-convex structure 5 can also be randomly distributed on the side of the pad unit 41 that contacts the solder ribbon 3, but the soldering effect may be relatively reduced.

[0062] Preferably, if Figure 4 As shown, the micro-concave-convex structure 5 is formed by dispersed pits 51, so that the side of the pad unit 41 that contacts the solder ribbon 3 has various pits 51, which are used to accommodate more soldering material to increase the soldering strength between the solder ribbon 3 and the pad unit 41. Specifically, the pits 51 are printed structures formed by metal material on the surface of the pad unit 41.

[0063] In some preferred embodiments, the pad 4 is formed by printing a paste on the photovoltaic cell 1. The pit 51 can be printed as a hollow structure during the printing process of the pad unit 41, wherein the hollow structure serves as the pit 51, thereby forming the micro-concave-convex structure 5, ensuring good welding between the solder ribbon 3 and the pad 4, and further reducing the use of the pad 4 material, so that the cost can be further reduced. In this case, the metal material is the same as the material of the pad unit 41, including but not limited to silver. It is understandable that the micro-concave-convex structure 5 can also be a metal material printed on the side of the pad unit 41 that contacts the solder ribbon 3, so that a convex structure is formed on the surface of the pad unit 41, so that the micro-concave-convex structure 5 is formed on the surface of the pad unit 41 to increase the contact area between the solder ribbon 3 and the pad unit 41. The metal material can be one of copper, solder paste, aluminum, and silver, which is not specifically limited in this application. However, the provision of the convex structure may increase the shielding effect on sunlight and increase costs.

[0064] Furthermore, the height of the pad unit 41 is greater than the height of the pit 51, so that the pit 51 is formed on the surface of the pad unit 41. The height of the pad 4 is H1, and the depth of the pit 51 is H2. The ratio of the depth H2 of the pit 51 to the height H1 of the pad 4 is 1:(5-20). The ratio of the depth of the pit 51 to the height of the pad 4 is within the range of 1:(5-20). The soldering material has a good climbing effect on the pad 4 and the conductive wire 42, which can simultaneously take into account the welding strength and production cost. The ratio of the depth of the pit 51 to the height of the pad 4 is exemplarily 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, and 1:20, but is not limited thereto.

[0065] Optionally, the height H1 of the solder pad 4 is 0.1mm to 0.3mm. If the height H1 of the solder pad 4 is greater than 0.3mm, it may cause excessive heat, damage the performance of the battery cell 1, and may increase the resistance of the solder joint, resulting in power loss, which will also increase costs and increase the light blocking effect. If the height H1 of the solder pad 4 is less than 0.1mm, it may cause insufficient heat during welding, resulting in a cold solder joint or a weak solder joint, and may not provide sufficient current carrying capacity. Subsequently, providing the micro-concave-convex structure 5 on its surface may not only fail to improve the welding strength, but may increase the welding reliability of the solder ribbon 3 and the solder pad unit 41, while reducing the photoelectric conversion efficiency of the battery cell 1. The height H1 of the solder pad 4 is exemplarily 0.1mm, 0.15mm, 0.2mm, 0.25mm, and 0.3mm, but is not limited thereto.

[0066] Optionally, the recessed depth H2 of the dimple 51 is between 0.01 mm and 0.1 mm, which promotes the soldering material's ability to climb onto the pad 4 and the conductive wire 42 and enhances the fluidity of the soldering material on the surface of the pad unit 41, thereby forming evenly distributed solder joints on the pad unit 41 and further improving the soldering quality between the solder ribbon 3 and the pad 4. If the recessed depth H2 of the dimple 51 is greater than 0.1 mm, the current carrying capacity of the pad unit 41 will be significantly weakened, reducing the photoelectric conversion efficiency. It will also hinder the soldering material's ability to climb, resulting in reduced soldering quality and, consequently, reduced reliability of the solar cell. If the recessed depth H2 of the dimple 51 is less than 0.01 mm, the improvement in the contact area between the solder ribbon 3 and the pad unit 41 will be weakened, reducing the soldering strength between the circular and elliptical solder ribbons 3 and the pad 4, making them unsuitable for use in circular and elliptical applications. The recessed depth of the pit 51 may be 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, or 0.1 mm, for example, but is not limited thereto.

[0067] Optionally, the recessed width of the pit 51 is W4, and the recessed width W4 of the pit 51 is 0.05mm to 0.1mm. Combined with the spacing W3 between adjacent pad units 41, it is beneficial to simultaneously control welding quality and cost. If the recessed width W4 of the pit 51 is greater than 0.1mm, the current carrying capacity of the pad unit 41 will be significantly weakened, reducing the photoelectric conversion efficiency. At the same time, it will also hinder the climbing effect of the welding material, reduce the welding quality, and fail to promote the formation of more welding points; if the recessed width W4 of the pit 51 is less than 0.05mm, it is also not conducive to the climbing of the welding material, the contact area between the welding ribbon 3 and the pad unit 41 is reduced, and the welding quality is also reduced, increasing the cost of using silver paste. The recessed width W4 of the pit 51 can be 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, or 0.1mm, but is not limited thereto.

[0068] In some embodiments, the shape of the dimples 51 is pyramidal. The pyramidal dimple 51 structure facilitates uniform distribution of the soldering material on the surface of the pad unit 41. In other embodiments, the dimples 51 are shaped as one or more of a cube, a prism, a cuboid, and a cylinder. The dimples 51 are arranged at intervals on the pad unit 41. The intervals between the dimples 51 on the pad unit 41 not only ensure the current carrying capacity of the pad 4, but also help promote the climbing effect of the soldering material on the pad 4 and the conductive wire 42, shortening the distance between the wires or the pad 4, and reducing the path length of the current flow, thereby reducing the impedance of the circuit.

[0069] Correspondingly, the present invention also provides a solar cell assembly, comprising the solar cell.

[0070] It can be understood that a plurality of battery cells 1 are subjected to steps such as string welding, lamination, and packaging to form a solar cell module. The solar cell module includes two battery strings in the second direction and an intermediate bus bar for connecting two adjacent battery strings in parallel. Specifically, the battery cells 1 can be connected in series by welding ribbons 3 to form battery strings arranged in sequence. The bus bar can be set at the stacking position of the adjacent battery strings and in direct contact with the battery cells 1, which can reduce the length of the current path, thereby reducing the series resistance and improving the electrical performance of the module. In addition, the bus bar at the stacking position can provide additional mechanical support for the battery cell 1 and enhance the structural stability of the module. Of course, there can also be a blank area between two adjacent battery strings. The bus bar can also be set at the blank area of ​​the two adjacent battery strings and is not in direct contact with the battery cell 1. The bus bar is also set at the end of the battery string and is in direct contact with the battery cell 1. The end is the head end and the tail end in the first direction.

[0071] It is understandable that the solar cell assembly may further include a metal frame, a front plate, a back plate and an adhesive film.

[0072] The backplane can protect and support the battery string, and has reliable insulation, water resistance and aging resistance. The backplane can have multiple options, usually tempered glass, organic glass, aluminum alloy TPT composite film, KPC, CPC, etc., which can be specifically set according to the specific situation and is not specifically limited in this application.

[0073] A front panel, such as photovoltaic glass, can be covered on the adhesive film on the light-receiving surface of the solar cell. The front panel can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, which can protect the solar cell 1 without affecting the efficiency of the solar cell 1 as much as possible. At the same time, the adhesive film can bond the front panel and the solar cell together. The adhesive film can seal, insulate, and waterproof the solar cell. There are multiple options for the adhesive film, including but not limited to a stack of one or more of an EPE adhesive film layer, an EVA adhesive film layer, a POE adhesive film layer, and an EVA-POE adhesive film layer. The back panel, solar cell, adhesive film and front panel can be arranged on a metal frame as a whole. The metal frame serves as the main external support structure of the entire solar cell assembly and can provide stable support and installation for the solar cell assembly. For example, the solar cell assembly can be installed at the required location through the metal frame.

[0074] Accordingly, the present invention also provides a photovoltaic system comprising the solar cell modules. It is understood that the solar cell modules can be electrically connected in parallel or in series, and the specific configuration can be selected according to actual needs.

[0075] In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array can be an array combination of multiple battery modules. For example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter to be converted into the alternating current required by the mains power grid and then connected to the mains power network to achieve solar power supply.

[0076] The above disclosure is only a preferred embodiment of the present invention and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope covered by the present invention.

Claims

1. A solar cell, characterized in that: include: A plurality of battery cells, each having a grid line disposed on its front surface; Welding strips for connecting the battery cells and arranging them in sequence; The pad is arranged on the gate line, the soldering strip is connected to the pad, the pad is composed of a plurality of pad units, and the plurality of pad units are connected by conductive lines.

2. The solar cell according to claim 1, wherein The ratio of the width of the soldering strip to the width of the soldering pad unit is 1:(0.25-0.5).

3. The solar cell according to claim 2, wherein The width of the pad unit is 0.1 mm to 0.5 mm; The distance between adjacent pad units is 0.1 mm to 0.5 mm.

4. The solar cell according to claim 1, wherein The cross-sectional shape of the welding strip is one of a circle and an ellipse.

5. The solar cell according to claim 1 or 4, wherein: A surface of the pad unit in contact with the soldering strip has a micro-concave-convex structure.

6. The solar cell according to claim 5, wherein The side of the pad unit that contacts the soldering strip has a uniformly distributed micro-concave-convex structure.

7. The solar cell according to claim 5, wherein The micro concavo-convex structure is formed by dispersed pits.

8. The solar cell according to claim 7, wherein The ratio of the depth of the pit to the height of the pad is 1:(5-20).

9. The solar cell according to claim 7 or 8, wherein: The depth of the pit is 0.01 mm to 0.1 mm, and the width of the pit is 0.05 mm to 0.1 mm.

10. The solar cell according to claim 7, wherein The shape of the pit is pyramidal.

11. The solar cell according to claim 7, wherein The shape of the pits is one or more of a cube, a prism, a cuboid, and a cylinder, and the pits are arranged at intervals on the pad unit.

12. The solar cell according to claim 7, wherein The pit is a printed structure formed by a metal material on the surface of the pad unit.

13. The solar cell according to claim 12, wherein The metal material is one of copper, solder paste, aluminum and silver.

14. The solar cell according to claim 1, wherein The cross-section of the pad is a rectangle, and the cross-section of the pad unit is one or more of a rectangle, a square, and a circle.

15. The solar cell according to claim 1, wherein The conductive wire is made of one of solder paste, conductive adhesive, copper, aluminum, and silver.

16. A solar cell module, characterized in that: The solar cell comprises the solar cell according to any one of claims 1 to 15.

17. A photovoltaic system, characterized in that: Comprising the solar cell module according to claim 16.

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