Solar cell module and system thereof

Abstract

The invention relates to the technical field of solar cells, and discloses a solar cell module which comprises a plurality of back contact cells and a plurality of welding strips. The back contact battery comprises a battery substrate and a grid line arranged on the surface of the battery substrate, a plurality of Pad points are arranged on the grid line, each welding strip is connected with the grid line through the Pad points, each welding strip is further connected with the grid line through a welding point, and the welding point is a non-Pad point; the total number of welding points and Pad points, connected with the grid line, of each welding strip is x, the main grid power loss of the back contact battery is y, x and y meet the following formula I: y = a * xb, and a and b are constants. According to the invention, the transmission loss of current carriers can be reduced, and the CTM loss of the assembly can be reduced.

Description

Technical Field

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

[0002] A back-contact solar cell is a cell in which both the emitter and base contact electrodes are placed on the back side of the cell (non-light-receiving side). The light-receiving side of the cell is not blocked by any metal electrode, which effectively increases the short-circuit current of the cell. At the same time, the back side can allow for wider metal grid lines to reduce the series resistance and thus increase the fill factor. This type of cell with no obstruction on the front side not only has a high conversion efficiency, but also looks more beautiful. At the same time, components with full back electrodes are easier to assemble.

[0003] In a back-contact solar cell, several main grids and fine grids are arranged vertically and crosswise, and the opposite grid lines are arranged in an interlaced manner. The main grid contains several pad points, and the welding strip is connected to the battery through the pad points. The flow direction of the current is collected from the fine grid to the main grid and then transmitted to the welding strip.

[0004] In order to improve the carrier collection efficiency, the fine grid is usually extended to the edge of the silicon wafer. However, the distance between the fine grid carrier transmission to the pad point is inconsistent between the two pad points. For the fine grid in the center of the battery, the fine grid closer to the center of the pad point has a shorter transmission distance and a smaller transmission loss; the fine grid farther away from the center of the pad point has a longer transmission distance and a larger transmission loss. For the fine grid at the edge of the battery, the transmission path is much longer than the fine grid in the middle, and the distance for the carrier to flow from the edge fine grid to the pad point is long, and the transmission loss is large, resulting in large CTM loss of the component. Summary of the invention

[0005] The invention provides a solar cell assembly and a system thereof, which can reduce the transmission loss of carriers and reduce the CTM loss of the assembly.

[0006] In order to solve the above technical problems, the present invention provides a solar cell assembly, comprising a plurality of back contact cells and a plurality of welding ribbons;

[0007] The back contact battery comprises a battery substrate and grid lines arranged on the surface of the battery substrate, wherein the grid lines comprise a main grid and a fine grid, wherein:

[0008] The gate line is provided with a plurality of pad points, each welding strip is connected to the gate line through the pad point, and each welding strip is also connected to the gate line through a welding point, wherein the welding point is a non-pad point;

[0009] The total number of welding points and pad points connected to each welding strip and the grid line is x, and the main grid power loss of the back contact battery is y, and x and y satisfy the following formula I: y = a*x b , a and b are constants.

[0010] Optionally, the value range of a is 800 to 950, the value range of b is -(1 to 3), and the value range of x is 5 to 30.

[0011] Optionally, x and y satisfy: y = (850-950) * x -2 ; The value range of x is 6-30, and the value range of y is 1-25w.

[0012] Optionally, x and y satisfy: y = (870-920) * x -2 ;

[0013] The value range of x is 8-20, and the value range of y is 1.2-15w.

[0014] Optionally, the total number of welding points and pad points connected to each welding strip and the grid line is x, the warping height of the half-cell of the back contact cell is h, and x and h satisfy the following formula II:

[0015] h=cx 3 +dx 2 +ex+f, where c, d, e, and f are constants.

[0016] Optionally, the value range of c is -(0.0001 to 0.001), the value range of d is 0.01 to 0.06, the value range of e is 0.01 to 0.1, and the value range of f is 0.01 to 0.1.

[0017] Optionally, x and h satisfy: h = -(0.0001-0.001)x 3 +(0.01~0.05)x 2 +(0.02~0.06)x+(0.02~0.06), where the value range of x is 5-30.

[0018] Optionally, x and h satisfy: h = -(0.0002-0.0006)x 3 +(0.01~0.03)x 2 +(0.02~0.04)x+(0.02~0.04), where the value range of x is 6-20.

[0019] Optionally, the warping height h ranges from 0.5 to 7 mm.

[0020] Optionally, the distance between two adjacent welding points is D, and the value range of D is 3 to 30 mm.

[0021] Optionally, the ratio of the number of welding points to Pad points is (1-6): (1-2).

[0022] Optionally, the grid lines include a main grid and a fine grid which are cross-arranged with each other on the surface of the battery substrate, a plurality of pad points are provided on the main grid, and a plurality of welding points are provided on the main grid and / or the fine grid; the plurality of welding strips include a first welding strip, the first welding strip is connected to the pad point on the main grid, and the first welding strip is also connected to the main grid and / or the fine grid through welding points.

[0023] Optionally, the grid lines include a main grid and a fine grid which are cross-arranged on the surface of the battery substrate, and a plurality of pad points and welding points are provided on the fine grid between the main grid closest to the edge of the battery substrate and the edge of the battery substrate; the plurality of welding strips include a second welding strip, the second welding strip is connected to the pad point on the fine grid, and the second welding strip is also connected to the fine grid located between the edge of the battery substrate and the main grid closest to the edge of the battery substrate through a welding point.

[0024] Optionally, the welding points are fixed points formed after screen printing.

[0025] Optionally, the shape of the welding point is one or more of a cube, a cuboid, a sphere, a cylinder, a cone, and a prism.

[0026] Optionally, a projection area of ​​the welding point on the battery substrate is 0.1 square millimeters to 1.5 square millimeters.

[0027] Optionally, two adjacent welding points are arranged at equal intervals.

[0028] Optionally, the welding point is one or more of a solder paste point, a silver paste point, a copper paste point, and a silver-copper point.

[0029] Optionally, each of the solder strips is connected to the Pad point via a metal layer.

[0030] Optionally, the metal layer is one or more of a solder paste layer, a silver paste layer, a copper paste layer, and a silver-copper paste layer.

[0031] Optionally, the welding points include a first welding point and a second welding point, the first welding point is located at two ends of the main grid, and the second welding point is located between the first welding points.

[0032] Optionally, the area of ​​the first welding point is smaller than the area of ​​the second welding point.

[0033] Optionally, the area of ​​the first welding point is 0.1 square millimeters to 1.0 square millimeters, and the area of ​​the second welding point is 0.5 square millimeters to 1.5 square millimeters.

[0034] Optionally, the Pad point includes a first Pad point and a second Pad point, the first Pad point is located at two ends of the main grid, and the second Pad point is located between the first Pad points.

[0035] Optionally, the area of ​​the first Pad point is greater than the area of ​​the second Pad point.

[0036] On the other hand, an embodiment of the present invention further provides a solar cell system, comprising the above-mentioned solar cell module assembly.

[0037] Implementing the embodiments of the present invention has the following beneficial effects:

[0038] The grid line of the present invention is provided with a plurality of pad points and welding points, each welding strip is connected to the grid line through the pad point, and the welding strip is also connected to the grid line through the welding point. In addition to each welding strip being connected to the solar cell module through the pad point, the present invention adds welding points on the main grid and / or the fine grid, and the welding strip is also connected to the main grid and / or the fine grid through the welding points, which can shorten the carrier transmission distance and reduce the transmission loss.

[0039] Moreover, there is a certain relationship between the number of welding points and the main grid power loss. The welding point is a key component for connecting the positive and negative electrodes inside the battery, and its number will directly affect the transmission path and uniformity of the current inside the battery. The total number of welding points and Pad points connecting each welding strip with the grid line of the present invention is x, and the main grid power loss of the back contact battery is y. When x and y satisfy the following formula I: y = a*x b , which can shorten the carrier transmission distance and reduce the carrier transmission loss. At the same time, it can effectively improve the current uniformity, reduce the internal resistance of the battery, thereby improving the overall performance of the battery and reducing the CTM loss of the component. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic structural diagram of an embodiment of a solar cell assembly of the present invention;

[0041] Figure 2 yes Figure 1 Enlarged view of the soldering point and pad point shown;

[0042] Figure 3 yes Figure 1 The schematic diagram of the structure of the solar cell module and the welding ribbon shown;

[0043] Figure 4 is a schematic structural diagram of another embodiment of a solar cell assembly of the present invention;

[0044] Figure 5 yes Figure 4 Enlarged view of the soldering point and pad point shown;

[0045] Figure 6 yes Figure 4 The schematic diagram of the structure of the solar cell module and the welding ribbon shown;

[0046] Figure 7 is a relationship diagram between the total number x of welding points and Pad points and the main grid power loss y of the present invention;

[0047] Figure 8 is a relationship diagram between the total number x of welding points and Pad points of the present invention and the warping height h of a half-cell battery;

[0048] Fig. 9 It is a schematic diagram of another embodiment of the welding point and the Pad point of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that the directional terms such as up, down, left, right, front, back, inside, outside, etc. that appear or will appear in the text of the present invention are only based on the accompanying drawings of the present invention, and are not specific limitations of the present invention.

[0050] The present invention provides a solar cell assembly, comprising: a plurality of back-contact cells 1, and a plurality of welding strips 2; the back-contact cells 1 comprise a cell substrate 10, a grid line 20 arranged on the surface of the cell substrate 10, the grid line 20 being provided with a plurality of pad points 30 and welding points 40, each welding strip 2 being connected to the grid line 20 via the pad point 30, and the welding strip 2 being also connected to the grid line 20 via the welding point 40, wherein the welding point is a non-pad point.

[0051] For a solar cell module, the grid lines 20 generally include a main grid and a thin grid, which are cross-arranged on the surface of the cell substrate, the main grid and the welding strip extend along a first direction, and the thin grid extends along a second direction.

[0052] In addition to each welding strip 2 being connected to the solar cell assembly 1 via the Pad point 30, the embodiment of the present invention adds a welding point 40 on the main grid and / or the fine grid, and the welding strip 2 is also connected to the main grid and / or the fine grid via the welding point 40. When the current is collected from the fine grid to the main grid and then transmitted to the welding strip, the transmission path of the current is redistributed, which can shorten the carrier transmission distance and reduce the transmission loss.

[0053] In addition, there is a certain relationship between the number of additional welding points 40 and the main grid power loss. The welding points are key components for connecting the positive and negative electrodes inside the battery, and their number will directly affect the transmission path and uniformity of the current inside the battery.

[0054] It should be noted that the Pad point is a metal electrode designed at a specific position on the surface of a solar cell, which plays an important role in connecting the electrical connection between the cell and the circuit board. These points are usually used to connect electrodes and wires, as well as to connect other photovoltaic components, such as connecting multiple cells in series to form a battery pack, or connecting multiple battery packs in parallel to form a photovoltaic cell array. In addition, the Pad point can also withstand the high voltage in the solar photovoltaic system to ensure the stable operation of the system. Therefore, it is known to those skilled in the art that the place where the width of the grid line suddenly widens can be identified as a Pad point.

[0055] The total number of welding points and pad points connecting each welding strip 2 and the grid line 20 is x, and the main grid power loss of the back contact battery is y. When x and y satisfy the following formula I: y = a*x b , which can shorten the carrier transmission distance and reduce the carrier transmission loss. At the same time, it can effectively improve the current uniformity, reduce the internal resistance of the battery, thereby improving the overall performance of the battery and reducing the CTM loss of the component.

[0056] Each welding strip 2 is connected to the grid line 20 through a combination of welding points and Pad points. Based on a certain Pad point, when the number of welding points is too small, the current transmission may be unbalanced, resulting in excessive current density in some areas and insufficient current density in other areas. When the number of welding points is too large, the effect of collecting current is reduced, and the internal resistance may be increased due to occupying too much space, and the cost is too high, and it is also easy to cause warping and even cracks. Therefore, it is necessary to find a balance point in the number of welding points and Pad points. The right amount of welding points can shorten the carrier transmission distance and reduce the transmission loss of carriers. At the same time, it can also effectively improve the current uniformity, help reduce the resistance inside the battery, and allow the current to flow more smoothly, thereby reducing the power loss caused by resistance.

[0057] Embodiment 1

[0058] like Figure 1-Figure 3 As shown, the present invention provides a solar cell assembly, comprising: a plurality of back contact cells 1, a plurality of welding strips 2; the back contact cells 1 comprise a cell substrate 10, and grid lines 20 arranged on the surface of the cell substrate 10.

[0059] The grid line 20 includes a main grid 21 and a fine grid 22 which are arranged crosswise on the surface of the battery substrate. The main grid 21 and the welding strip 2 extend along a first direction, and the fine grid 22 extends along a second direction. The main grid 21 is provided with a plurality of pad points 30, and the main grid 21 and / or the fine grid 22 are provided with a plurality of welding points 40; the plurality of welding strips 2 include a first welding strip, which is connected to the pad point 30 on the main grid 21, and the first welding strip is also connected to the main grid 21 and / or the fine grid 22 through a welding point 40. Among them, the welding point is a non-pad point.

[0060] Preferably, each of the welding strips 2 is connected to the main grid 21 through a Pad point 30, and each of the welding strips 2 is also connected to the main grid 21 and / or the fine grid 22 through a welding point 40. The welding point 40 can be arranged on the main grid 21, on the fine grid 22, or at the junction of the main grid 21 and the fine grid 22.

[0061] It should be noted that, in conjunction with the drawings, the first direction of this embodiment is a vertical direction, and the second direction is a horizontal direction.

[0062] It should also be noted that a number of main grids 21 and fine grids 22 are arranged vertically and crosswise, the fine grids 22 are used to collect currents in polar regions, and the opposite polarity grid lines are arranged in an interlaced manner. Specifically, the fine grids 22 include a first grid line for collecting currents in a first polar region and a second grid line for collecting currents in a second polar region, the polarities of the first grid line and the second grid line are opposite, and the polarities of the first polar region and the second polar region are also opposite. The main grid includes a first main grid and a second main grid, the first main grid is connected to the first grid line, the second main grid is connected to the second grid line, the carriers collected by the first fine grid are collected to the first main grid and then transmitted to the first welding strip, and the carriers collected by the second fine grid are collected to the second main grid and then transmitted to the second welding strip.

[0063] For example, the first main grid is a positive main grid, the first grid line is a positive grid line, and is used to collect positive current in the positive region, then the second main grid is a negative main grid, the second grid line is a negative grid line, and is used to collect negative current in the negative region; or, the first main grid is a negative main grid, the first grid line is a negative grid line, and is used to collect negative current in the negative region, then the second main grid is a positive main grid, the second grid line is a positive grid line, and is used to collect positive current in the positive region. The positive grid line is arranged in the P-type doping region of the solar cell module, and the negative grid line is arranged in the N-type doping region of the solar cell module.

[0064] The first grid line and the second grid line are alternately arranged, and the first grid line and the second grid line are both horizontal to the edge line of the solar cell assembly. The first grid line and the second grid line are alternately arranged in the vertical direction, and the first grid line and the second grid line are both horizontal to the upper edge line and the lower edge line of the solar cell assembly. The solar cell assembly is substantially rectangular, wherein the substantially rectangular solar cell assembly can be, for example, a square, or another rectangle, and can have standard corners, cut corners or rounded corners, which are arranged according to actual production needs and are not specifically limited here. At the same time, the number of the first grid line and the second grid line is determined according to the actual area size of the solar cell assembly, the width and distance of the first grid line and the second grid line, which are not specifically limited here. The solar cell assembly can also be sliced ​​to achieve battery cutting.

[0065] In some preferred embodiments, the fine grid 22 further includes an edge grid line 221 located at the edge of the battery substrate, and the edge grid line 221 is extended along the first direction. The edge grid line 221 can be connected to other fine grid lines of the same polarity arranged along the second direction.

[0066] Further, the first gate line or the second gate line is an aluminum gate line, a silver gate line, a copper gate line, or a silver-clad copper gate line. It is understandable that in the embodiment of the present invention, the first gate line and the second gate line can be selected to be gate lines of the same or different metal types, for example, the first gate line and the second gate line are both aluminum gate lines; or the first gate line is an aluminum gate line and the second gate line is a silver gate line.

[0067] In addition to each welding strip 2 being connected to the main grid 21 via the Pad point 30, welding points 40 are added to both the main grid 21 and the fine grid 22 in this embodiment of the present invention, and the welding strip 2 is also connected to the main grid 21 and the fine grid 22 via the welding points 40, which can shorten the carrier transmission distance and reduce the transmission loss.

[0068] In addition, there is a certain relationship between the number of additional welding points 40 and the main grid power loss. The welding points are key components for connecting the positive and negative electrodes inside the battery, and their number will directly affect the transmission path and uniformity of the current inside the battery.

[0069] like Figure 7 As shown, the total number of welding points and pad points connected to each welding strip 2 and the grid line 20 is x, and the main grid power loss of the back contact battery is y. When x and y satisfy the following formula I: y = a*x b , which can shorten the carrier transmission distance, reduce the carrier transmission loss, and effectively improve the current uniformity, reduce the internal resistance of the battery, thereby improving the overall performance of the battery and reducing the CTM loss of the component. The welding points and Pad points in this embodiment are preferably arranged on the main grid, and in this case, x is the total number of welding points and Pad points on a single main grid.

[0070] Each welding strip 2 is connected to the grid line 20 through a combination of welding points and Pad points. Based on a certain Pad point, when the number of welding points is too small, the current transmission may be unbalanced, resulting in excessive current density in some areas and insufficient current density in other areas. When the number of welding points is too large, the effect of collecting current is reduced, and the internal resistance may be increased due to occupying too much space, and the cost is too high, and it is also easy to cause warping and even cracks. Therefore, it is necessary to find a balance point in the number of welding points and Pad points. The right amount of welding points can shorten the carrier transmission distance and reduce the transmission loss of carriers. At the same time, it can also effectively improve the current uniformity, help reduce the resistance inside the battery, and allow the current to flow more smoothly, thereby reducing the power loss caused by resistance.

[0071] Among them, the value range of a is preferably 800-950, and can be 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, etc., but is not limited to this.

[0072] The value range of b is preferably -(1 to 3), specifically -1, -2, -3, etc., but is not limited thereto.

[0073] The value range of x is preferably 5-30, and can be specifically 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, etc., but is not limited thereto.

[0074] More preferably, x and y satisfy: y = (850-950) * x -2 ; The value range of x is 6-30, and the value range of y is 1-25w.

[0075] More preferably, x and y satisfy: y = (870-920) * x -2 ; The value range of x is 8-20, and the value range of y is 1.2-15w.

[0076] Figure 7 The relationship between the total number of welding points and pad points x and the main grid power loss y shown in the figure is one of the preferred embodiments of the present invention, and x and y satisfy: y = 896.64*x -2 The above relationship is only one of the implementation cases, and the values ​​of a and b can also be adjusted according to the grid line screen structure of the battery, the stacking structure of the battery, etc.

[0077] In this embodiment, a relationship I is established between the total number x of welding points and Pad points and the main grid power loss y, and the value range of x within a preset power loss range is obtained by deriving the relationship I. The welding strip is connected to the grid line through x welding points and Pad points.

[0078] In this embodiment, when the value range of x is 5-30, the spacing between the welding point 40 and the pad point 30 is reasonable, which can shorten the carrier transmission distance and reduce the carrier transmission loss. At the same time, it can effectively improve the current uniformity, help reduce the internal resistance of the battery, thereby reducing the main grid power loss and welding cost, and the main grid power loss is controlled within 1.00-25w. Further, when the value range of x is 8-20, the main grid power loss can be better controlled, and the main grid power loss can be reduced to 1.2-15w.

[0079] x is the total number of welding points 40 and pad points 30 connecting each welding strip 2 to the gate line 20. After the value range of x is determined, the specific number of welding points 40 and pad points 30 can be set according to actual needs. Preferably, the ratio of the number of welding points 40 and pad points 30 is (1-6): (1-2). This embodiment can shorten the carrier transmission distance and reduce the transmission loss of carriers by limiting the ratio of the number of welding points 40 and pad points 30, and can also control the total shielding area of ​​the welding points 40 and pad points 30 for the substrate, which is beneficial to reduce the impact on the substrate absorbing light and improve the working efficiency of the photovoltaic cell. More preferably, the ratio of the number of welding points 40 and pad points 30 is (1-4): (1-2).

[0080] In some preferred embodiments, the distance between two adjacent welding points is D, and the value range of D is 3 to 30 mm. The spacing between welding points has a certain influence on the transmission path and uniformity of the current inside the battery. When D is 3 to 30 mm, the uniform distribution of the current inside the battery can be improved, and the power loss caused by uneven current density can be reduced. Too small a spacing may cause heat overlap between welding points; while too large a spacing may lengthen the current transmission path, resulting in increased power loss.

[0081] In some preferred embodiments, the welding point 40 is a fixed point formed by screen printing. The shape of the welding point is preferably one or more of a cube, a cuboid, a sphere, a cylinder, a cone, and a prism, but is not limited thereto. It is worth noting that both the welding point 40 and the pad point 30 can be formed by screen printing, and the area of ​​the welding point 40 is generally smaller than the area of ​​the pad point 30.

[0082] In some preferred embodiments, the projection area of ​​the welding point on the battery substrate is 0.1 square millimeters to 1.5 square millimeters, specifically 0.1 square millimeters, 0.2 square millimeters, 0.5 square millimeters, 0.7 square millimeters, 0.8 square millimeters, 1.0 square millimeters, 1.2 square millimeters, 1.3 square millimeters, 1.4 square millimeters, 1.5 square millimeters, but not limited to this.

[0083] In some preferred embodiments, two adjacent welding points are arranged at equal intervals. With welding points arranged at equal intervals, the resistance inside the battery is evenly distributed, thus reducing power loss caused by uneven current density.

[0084] In some preferred embodiments, the welding point 40 is one or more of a solder paste point, a silver paste point, a copper paste point, and a silver-copper point, but is not limited thereto.

[0085] In some preferred embodiments, each solder strip 2 is indirectly connected to the pad point 30, and can be connected through a metal layer 50. The metal layer is preferably one or more of a solder paste layer, a silver paste layer, a copper paste layer, and a silver-copper paste layer, but is not limited thereto.

[0086] Embodiment 2

[0087] like Figure 4-Figure 6 As shown, this embodiment provides a solar cell assembly, including: a plurality of back contact cells 1, a plurality of welding strips 2; the back contact cells 1 include a cell substrate 10, and grid lines 20 arranged on the surface of the cell substrate 10.

[0088] The grid line 20 includes a main grid 21 and a thin grid 22 which are arranged crosswise on the surface of the battery substrate. The main grid 21 and the welding strip 2 extend along a first direction, and the thin grid 22 extends along a second direction. The main grid 21 is provided with a plurality of pad points 30, and the main grid 21 is provided with a plurality of welding points 40; each of the welding strips 2 is connected to the grid line 20 through the pad point 30, and each of the welding strips 2 is also connected to the main grid 21 through the welding point 40.

[0089] A plurality of pad points 30 and welding points 40 are provided on the fine grid 22 between the main grid 21 closest to the edge of the battery substrate and the edge of the battery substrate; the plurality of welding strips include a second welding strip, the second welding strip is connected to the pad point on the fine grid, and the second welding strip is also connected to the fine grid located between the edge of the battery substrate and the main grid closest to the edge of the battery substrate through the welding point 40. The welding point is a non-pad point.

[0090] It should be noted that, in combination with the diagram, the first direction of this embodiment is the vertical direction, and the second direction is the horizontal direction. The edge of the battery substrate includes a first edge parallel to the main grid, which is located on the left and right sides of the solar cell, and a second edge parallel to the fine grid, which is located on the upper and lower sides of the solar cell.

[0091] It should also be noted that the main grid of this embodiment is located near the middle area of ​​the battery substrate, and the main grid near the middle area can be a continuous main grid or a segmented main grid, preferably a continuous main grid. A fine grid 22 is provided at the edge of the battery substrate, and the fine grid 22 at the edge of the battery substrate is used to collect the current in the edge polarity area. The main grid near the edge area can be a segmented main grid or no main grid, preferably a segmented main grid.

[0092] A plurality of main grids 21 and fine grids 22 are arranged vertically and crosswise, the fine grids 22 are used to collect currents in polar regions, and the opposite polarity grid lines are arranged in an interlaced manner. Specifically, the fine grids 22 include a first grid line for collecting currents in a first polar region and a second grid line for collecting currents in a second polar region, the polarities of the first grid line and the second grid line are opposite, and the polarities of the first polar region and the second polar region are also opposite. The main grid 21 includes a first main grid and a second main grid, the first main grid is connected to the first grid line, the second main grid is connected to the second grid line, the carriers collected by the first fine grid are collected to the first main grid and then transmitted to the first welding strip, and the carriers collected by the second fine grid are collected to the second main grid and then transmitted to the second welding strip.

[0093] For example, the first main grid is a positive main grid, the first grid line is a positive grid line, and is used to collect positive current in the positive region, then the second main grid is a negative main grid, the second grid line is a negative grid line, and is used to collect negative current in the negative region; or, the first main grid is a negative main grid, the first grid line is a negative grid line, and is used to collect negative current in the negative region, then the second main grid is a positive main grid, the second grid line is a positive grid line, and is used to collect positive current in the positive region. The positive grid line is arranged in the P-type doping region of the solar cell module, and the negative grid line is arranged in the N-type doping region of the solar cell module.

[0094] The first grid line and the second grid line are alternately arranged, and the first grid line and the second grid line are both horizontal to the edge line of the solar cell assembly. The first grid line and the second grid line are alternately arranged in the vertical direction, and the first grid line and the second grid line are both horizontal to the upper edge line and the lower edge line of the solar cell assembly. The solar cell assembly is substantially rectangular, wherein the substantially rectangular solar cell assembly can be, for example, a square, or another rectangle, and can have standard corners, cut corners or rounded corners, which are arranged according to actual production needs and are not specifically limited here. At the same time, the number of the first grid line and the second grid line is determined according to the actual area size of the solar cell assembly, the width and distance of the first grid line and the second grid line, which are not specifically limited here. The solar cell assembly can also be sliced ​​to achieve battery cutting.

[0095] In some preferred embodiments, the fine grid 22 further includes an edge grid line 221 located at the edge of the battery substrate, and the edge grid line 221 is extended along the first direction. The edge grid line 221 can be connected to other fine grid lines of the same polarity arranged along the second direction.

[0096] Further, the first gate line or the second gate line is an aluminum gate line, a silver gate line, a copper gate line, or a silver-clad copper gate line. It is understandable that in the embodiment of the present invention, the first gate line and the second gate line can be selected to be gate lines of the same or different metal types, for example, the first gate line and the second gate line are both aluminum gate lines; or the first gate line is an aluminum gate line and the second gate line is a silver gate line.

[0097] In addition to each welding strip 2 being connected to the grid line 20 via the Pad point 30, welding points 40 are added to the main grid 21 and the fine grid 22 located at the edge of the battery substrate in the embodiment of the present invention. The welding strip 2 is also connected to the main grid 21 and the fine grid 22 located at the edge of the battery substrate via the welding points 40, which can shorten the carrier transmission distance and reduce the transmission loss.

[0098] In addition, there is a certain relationship between the number of additional welding points 40 and the main grid power loss. The welding points are key components for connecting the positive and negative electrodes inside the battery, and their number will directly affect the transmission path and uniformity of the current inside the battery.

[0099] like Figure 7 As shown, the total number of welding points and pad points connected to each welding strip 2 and the grid line 20 is x, and the main grid power loss of the back contact battery is y. When x and y satisfy the following formula I: y = a*x b, which can shorten the carrier transmission distance, reduce the carrier transmission loss, and effectively improve the current uniformity, reduce the resistance inside the battery, thereby improving the overall performance of the battery and reducing the CTM loss of the component. The welding points and Pad points in this embodiment are preferably arranged on the main grid and the fine grid in the edge area. At this time, x is the total number of welding points and Pad points on a single main grid, and / or, x is the total number of welding points and Pad points located on the same straight line along the extension direction of the main grid.

[0100] Each welding strip 2 is connected to the grid line 20 through a combination of welding points and Pad points. Based on a certain Pad point, when the number of welding points is too small, the current transmission may be unbalanced, resulting in excessive current density in some areas and insufficient current density in other areas. When the number of welding points is too large, the effect of collecting current is reduced, and the internal resistance may be increased due to occupying too much space, and the cost is too high, and it is also easy to cause warping and even cracks. Therefore, it is necessary to find a balance point in the number of welding points and Pad points. The right amount of welding points can shorten the carrier transmission distance and reduce the transmission loss of carriers. At the same time, it can also effectively improve the current uniformity, help reduce the resistance inside the battery, and allow the current to flow more smoothly, thereby reducing the power loss caused by resistance.

[0101] Among them, the value range of a is preferably 800-950, and can be 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, etc., but is not limited to this.

[0102] The value range of b is preferably -(1 to 3), specifically -1, -2, -3, etc., but is not limited thereto.

[0103] The value range of x is preferably 5-30, and can be specifically 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, etc., but is not limited thereto.

[0104] More preferably, x and y satisfy: y = (850-950) * x -2 ; The value range of x is 6-30, and the value range of y is 1-25w.

[0105] More preferably, x and y satisfy: y = (870-920) * x -2 ; The value range of x is 8-20, and the value range of y is 1.2-15w.

[0106] Figure 7 The relationship between the total number of welding points and pad points x and the main grid power loss y shown in the figure is one of the preferred embodiments of the present invention, and x and y satisfy: y = 896.64*x-2 The above relationship is only one of the implementation cases, and the values ​​of a and b can also be adjusted according to the grid line screen structure of the battery, the stacking structure of the battery, etc.

[0107] In this embodiment, a relationship I is established between the total number x of welding points and Pad points connecting each welding strip 2 and the gate line 20 and the main grid power loss y. By deriving the relationship I, the value range of x within the preset power loss range is obtained. The welding strip is connected to the gate line through x welding points 40 and Pad points 30.

[0108] In this embodiment, when the value range of x is 5-30, the spacing between the welding point 40 and the pad point 30 is reasonable, which can shorten the carrier transmission distance and reduce the carrier transmission loss. At the same time, it can effectively improve the current uniformity, help reduce the internal resistance of the battery, thereby reducing the main grid power loss and welding cost, and the main grid power loss is controlled within 1.00-25w. Further, when the value range of x is 8-20, the main grid power loss can be better controlled, and the main grid power loss can be reduced to 1.2-15w.

[0109] x is the total number of welding points and pad points connecting each welding strip 2 to the gate line 20. After the value range of x is determined, the specific number of welding points 40 and pad points 30 can be set according to actual needs. Preferably, the ratio of the number of welding points 40 and pad points 30 is (1-6): (1-2). By limiting the ratio of the number of welding points 40 and pad points 30, this embodiment can not only shorten the carrier transmission distance and reduce the transmission loss of the carrier, but also control the total shielding area of ​​the welding points 40 and pad points 30 for the substrate, which is beneficial to reduce the impact on the substrate absorbing light and improve the working efficiency of the photovoltaic cell. More preferably, the ratio of the number of welding points 40 and pad points 30 is (1-4): (1-2).

[0110] In some preferred embodiments, the distance between two adjacent welding points is D, and the value range of D is 3 to 30 mm. The spacing between welding points has a certain influence on the transmission path and uniformity of the current inside the battery. When D is 3 to 30 mm, the uniform distribution of the current inside the battery can be improved, and the power loss caused by uneven current density can be reduced. Too small a spacing may cause heat overlap between welding points; while too large a spacing may lengthen the current transmission path, resulting in increased power loss.

[0111] In some preferred embodiments, the welding point 40 is a fixed point formed by screen printing. The shape of the welding point is preferably one or more of a cube, a cuboid, a sphere, a cylinder, a cone, and a prism, but is not limited thereto. It is worth noting that both the welding point 40 and the pad point 30 can be formed by screen printing, and the area of ​​the welding point 40 is generally smaller than the area of ​​the pad point 30.

[0112] In some preferred embodiments, the projection area of ​​the welding point on the battery substrate is 0.1 square millimeters to 1.5 square millimeters, specifically 0.1 square millimeters, 0.2 square millimeters, 0.5 square millimeters, 0.7 square millimeters, 0.8 square millimeters, 1.0 square millimeters, 1.2 square millimeters, 1.3 square millimeters, 1.4 square millimeters, 1.5 square millimeters, but not limited to this.

[0113] In some preferred embodiments, two adjacent welding points are arranged at equal intervals. With welding points arranged at equal intervals, the resistance inside the battery is evenly distributed, thus reducing power loss caused by uneven current density.

[0114] In some preferred embodiments, the welding point 40 is one or more of a solder paste point, a silver paste point, a copper paste point, and a silver-copper point, but is not limited thereto.

[0115] In some preferred embodiments, each solder strip 2 is indirectly connected to the pad point 30, and can be connected through a metal layer 50. The metal layer is preferably one or more of a solder paste layer, a silver paste layer, a copper paste layer, and a silver-copper paste layer, but is not limited thereto.

[0116] Embodiment 3

[0117] Different from the first embodiment, this embodiment further defines the relationship between the total number x of welding points and pad points on each welding strip and the warping height h of the half-cell battery. During the battery production process, the formation of welding points often requires a high temperature process. During this process, the battery material may undergo thermal expansion or contraction. If the number or layout of welding points is inappropriate, the impact of this thermal stress may be aggravated, causing the battery to warp.

[0118] As the connection points of the internal components of the battery, the number and distribution of welding points may affect the stress distribution inside the battery. Figure 8 As shown, the total number of welding points and pad points connected to each welding strip and the grid line is x, the warping height of the half-cell of the back contact battery is h, and x and h satisfy the following formula II:

[0119] h=cx 3 +dx 2 +ex+f, where c, d, e, and f are constants.

[0120] When x and h satisfy the above relationship, the integrity of the battery structure can be enhanced and the battery's anti-warping ability can be improved through the appropriate number of welding points and reasonable layout. When the number of welding points is too small, the current transmission may be unbalanced, resulting in excessive current density in some areas and insufficient current density in other areas, and the battery structure is unstable. When the number of welding points is too large, the influence of thermal stress is greater, which can easily lead to warping or even cracking.

[0121] Among them, the value range of c is preferably -(0.0001 to 0.001), and can be specifically -0.0001, -0.0002, -0.0003, -0.0004, -0.0005, -0.0006, -0.0007, -0.0008, -0.0009, -0.001, etc., but is not limited thereto.

[0122] The value range of d is preferably 0.01 to 0.06, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, etc., but is not limited thereto.

[0123] The value range of e is preferably 0.01 to 0.1, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., but is not limited thereto.

[0124] The value range of f is preferably 0.01 to 0.1, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., but is not limited thereto.

[0125] More preferably, x and h satisfy: h = -(0.0001 to 0.001)x 3 +(0.01~0.05)x 2 +(0.02~0.06)x+(0.02~0.06), where the value range of x is 5-30.

[0126] More preferably, x and h satisfy: h = -(0.0002-0.0006)x 3 +(0.01~0.03)x 2 +(0.02~0.04)x+(0.02~0.04), where the value range of x is 6-20.

[0127] Figure 8 The relationship between the total number x of welding points and Pad points and the warpage height h of a half-cell is shown in the figure, which is a preferred embodiment of the present invention. x and h satisfy: h = -0.0004x 3+0.0193x 2 +0.0301x+0.0296. The above relationship is only one of the implementation cases, and the values ​​of c, d, e, and f can also be adjusted according to the grid line screen structure of the battery, the stacking structure of the battery, etc.

[0128] In this embodiment, based on Relationship Formula I, in which the total number of welding points and Pad points connecting each welding strip to the gate line is x and the main grid power loss y, Relationship Formula II is established between the total number of welding points and Pad points x connecting each welding strip to the gate line and the warping height h of the half-cell battery. By respectively deriving Relationship Formulas I and II, the value range of x under the preset power loss and the preset warping height range of the half-cell battery is obtained. The welding strip is connected to the gate line through x welding points 40 and Pad points 30.

[0129] In some preferred embodiments, the warping height h is in the range of 0.5 to 7 mm. Further preferably, the warping height h is in the range of 0.5 to 6.2 mm. More preferably, the warping height h is in the range of 0.5 to 5.0 mm.

[0130] Embodiment 4

[0131] Different from the second embodiment, this embodiment further defines the relationship between the total number x of welding points and pad points on each welding strip and the warping height h of the half-cell battery. During the battery production process, the formation of welding points often requires a high temperature process. During this process, the battery material may undergo thermal expansion or contraction. If the number or layout of welding points is inappropriate, the impact of this thermal stress may be aggravated, causing the battery to warp.

[0132] As the connection points of the internal components of the battery, the number and distribution of welding points may affect the stress distribution inside the battery. Figure 8 As shown, the total number of welding points and pad points connected to each welding strip and the grid line is x, the warping height of the half-cell of the back contact battery is h, and x and h satisfy the following formula II:

[0133] h=cx 3 +dx 2 +ex+f, where c, d, e, and f are constants.

[0134] When x and h satisfy the above relationship, the integrity of the battery structure can be enhanced and the battery's anti-warping ability can be improved through the appropriate number of welding points and reasonable layout. When the number of welding points is too small, the current transmission may be unbalanced, resulting in excessive current density in some areas and insufficient current density in other areas, and the battery structure is unstable. When the number of welding points is too large, the influence of thermal stress is greater, which can easily lead to warping or even cracking.

[0135] Among them, the value range of c is preferably -(0.0001 to 0.001), and can be specifically -0.0001, -0.0002, -0.0003, -0.0004, -0.0005, -0.0006, -0.0007, -0.0008, -0.0009, -0.001, etc., but is not limited thereto.

[0136] The value range of d is preferably 0.01 to 0.06, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, etc., but is not limited thereto.

[0137] The value range of e is preferably 0.01 to 0.1, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., but is not limited thereto.

[0138] The value range of f is preferably 0.01 to 0.1, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., but is not limited thereto.

[0139] More preferably, x and h satisfy: h = -(0.0001 to 0.001)x 3 +(0.01~0.05)x 2 +(0.02~0.06)x+(0.02~0.06), where the value range of x is 5-30.

[0140] More preferably, x and h satisfy: h = -(0.0002-0.0006)x 3 +(0.01~0.03)x 2 +(0.02~0.04)x+(0.02~0.04), where the value range of x is 6-20.

[0141] Figure 8 The relationship between the total number x of welding points and Pad points and the warpage height h of a half-cell is shown in the figure, which is a preferred embodiment of the present invention. x and h satisfy: h = -0.0004x 3 +0.0193x 2 +0.0301x+0.0296. The above relationship is only one of the implementation cases, and the values ​​of c, d, e, and f can also be adjusted according to the grid line screen structure of the battery, the stacking structure of the battery, etc.

[0142] In this embodiment, based on Relationship Formula I, in which the total number of welding points and Pad points connecting each welding strip to the gate line is x and the main grid power loss y, Relationship Formula II is established between the total number of welding points and Pad points x connecting each welding strip to the gate line and the warping height h of the half-cell battery. By respectively deriving Relationship Formulas I and II, the value range of x under the preset power loss and the preset warping height range of the half-cell battery is obtained. The welding strip is connected to the gate line through x welding points 40 and Pad points 30.

[0143] In some preferred embodiments, the warping height h is in the range of 0.5 to 7 mm. Further preferably, the warping height h is in the range of 0.5 to 6.2 mm. More preferably, the warping height h is in the range of 0.5 to 5.0 mm.

[0144] Embodiment 5

[0145] Different from the first to fourth embodiments, Fig. 9 As shown, the welding point 40 in this embodiment includes a first welding point 41 and a second welding point 42. The first welding point 41 is located at both ends of the main grid, and the second welding point 42 is located between the first welding points 41. The area of ​​the first welding point 41 is smaller than that of the second welding point 42.

[0146] During the load test of the shingled assembly, the load pressure is mainly borne by the edge of the battery cell, and when subjected to the load, the horizontal tension on both ends of the edge is relatively large. Therefore, the area of ​​the first welding point 41 of this embodiment is smaller than the area of ​​the second welding point 42, which ensures the welding yield and the required welding tension, makes the stress distribution more reasonable, enhances the integrity of the battery structure, and improves the anti-warping ability of the battery.

[0147] Preferably, the area of ​​the first welding point 41 is 0.1 square millimeter to 1.0 square millimeter, specifically 0.1 square millimeter, 0.2 square millimeter, 0.3 square millimeter, 0.4 square millimeter, 0.5 square millimeter, 0.6 square millimeter, 0.7 square millimeter, 0.8 square millimeter, 0.9 square millimeter, 1.0 square millimeter, etc., but is not limited to this.

[0148] The area of ​​the second welding point 42 is 0.5 square millimeters to 1.5 square millimeters, and can be 0.5 square millimeters, 0.6 square millimeters, 0.7 square millimeters, 0.8 square millimeters, 0.9 square millimeters, 1.0 square millimeters, 1.1 square millimeters, 1.2 square millimeters, 1.3 square millimeters, 1.4 square millimeters, 1.5 square millimeters, etc., but is not limited to this.

[0149] Embodiment 6

[0150] Different from the first to fourth embodiments, Fig. 9 As shown, the pad point 30 of this embodiment includes a first pad point 31 and a second pad point 32. The first pad point 31 is located at both ends of the main grid, and the second pad point 32 is located between the first welding points 31. The area of ​​the first pad point 31 is larger than that of the second pad point 32.

[0151] In this embodiment, the area of ​​the first Pad point 31 is larger than the area of ​​the second Pad point 32. The combination of the first Pad point 31 and the second Pad point 32 can not only ensure the welding effect, but also reduce the shielding of the substrate by the second Pad point 32, thereby helping to reduce the influence of the second Pad point 32 on the substrate absorbing light, which is beneficial to improving the working efficiency of the photovoltaic cell. At the same time, as the area of ​​the second Pad point 32 is reduced, the consumed silver paste will also be reduced accordingly, which is beneficial to reducing costs.

[0152] Embodiment 7

[0153] Welding design methods for solar cell modules, including:

[0154] A solar cell assembly is selected, wherein the solar cell assembly comprises a cell substrate and a grid line arranged on the surface of the cell substrate, wherein the grid line is provided with a plurality of pad points and welding points;

[0155] Establish the relationship between the total number of welding points and Pad points connecting each welding strip to the grid line and the main grid power loss of the back contact battery I: y = a*x-2, where a is a constant, x is the total number of welding points and Pad points connecting each welding strip to the grid line, and y is the main grid power loss of the back contact battery;

[0156] By deriving the relationship I, the value range of x under the preset main grid power loss range is obtained;

[0157] A welding strip is selected, and the welding strip is connected to the gate line through x welding points and a Pad point.

[0158] Among them, in relational formula I, the value range of a is preferably 800-950, specifically 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, etc., but not limited to this.

[0159] The value range of b is preferably -(1 to 3), specifically -1, -2, -3, etc., but is not limited thereto.

[0160] The value range of x is preferably 5-30, and can be specifically 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, etc., but is not limited thereto.

[0161] More preferably, x and y satisfy: y = (850-950) * x -2 ; The value range of x is 6-30, and the value range of y is 1-25w.

[0162] More preferably, x and y satisfy: y = (870-920) * x -2 ; The value range of x is 8-20, and the value range of y is 1.2-15w.

[0163] In this embodiment, a relationship I is established between the total number x of welding points and Pad points and the main grid power loss y, and the value range of x within a preset power loss range is obtained by deriving the relationship I. The welding strip is connected to the grid line through x welding points and Pad points.

[0164] In this embodiment, when the value range of x is 5-30, the spacing between the welding point 40 and the pad point 30 is reasonable, which can shorten the carrier transmission distance and reduce the carrier transmission loss. At the same time, it can effectively improve the current uniformity, help reduce the internal resistance of the battery, thereby reducing the main grid power loss and welding cost, and the main grid power loss is controlled within 1.00-25w. Further, when the value range of x is 8-20, the main grid power loss can be better controlled, and the main grid power loss can be reduced to 1.2-15w.

[0165] Embodiment 8

[0166] Welding design methods for solar cell modules, including:

[0167] A solar cell assembly is selected, wherein the solar cell assembly comprises a cell substrate and a grid line arranged on the surface of the cell substrate, wherein the grid line is provided with a plurality of pad points and welding points;

[0168] Establish the relationship between the total number of welding points and Pad points connecting each welding strip to the grid line and the main grid power loss of the back contact battery I: y = a*x-2, where a is a constant, x is the total number of welding points and Pad points connecting each welding strip to the grid line, and y is the main grid power loss of the back contact battery;

[0169] Establish the relationship between the welding point where each welding strip is connected to the grid line and the warping height of the half-cell II: h = bx 3 +cx 2+dx+e, where b, c, d, and e are constants, x is the total number of welding points and pad points where each welding strip is connected to the grid line, and h is the warpage height of the half-cell of the back contact battery:

[0170] By taking the derivative of the above-mentioned equations I and II, the value range of x is obtained;

[0171] Select a welding strip, wherein the welding strip is connected to the gate line through x welding points and a pad point;

[0172] Among them, in relational formula I, the value range of a is preferably 800-950, specifically 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, etc., but not limited to this.

[0173] The value range of b is preferably -(1 to 3), specifically -1, -2, -3, etc., but is not limited thereto.

[0174] The value range of x is preferably 5-30, and can be specifically 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, etc., but is not limited thereto.

[0175] More preferably, x and y satisfy: y = (850-950) * x -2 ; The value range of x is 6-30, and the value range of y is 1-25w.

[0176] More preferably, x and y satisfy: y = (870-920) * x -2 ; The value range of x is 8-20, and the value range of y is 1.2-15w.

[0177] In this embodiment, a relationship I is established between the total number x of welding points and Pad points and the main grid power loss y, and the value range of x within a preset power loss range is obtained by deriving the relationship I. The welding strip is connected to the grid line through x welding points and Pad points.

[0178] In this embodiment, when the value range of x is 5-30, the spacing between the welding point 40 and the pad point 30 is reasonable, which can shorten the carrier transmission distance and reduce the carrier transmission loss. At the same time, it can effectively improve the current uniformity, help reduce the internal resistance of the battery, thereby reducing the main grid power loss and welding cost, and the main grid power loss is controlled within 1.00-25w. Further, when the value range of x is 8-20, the main grid power loss can be better controlled, and the main grid power loss can be reduced to 1.2-15w.

[0179] In relational formula II, the value range of c is preferably -(0.0001 to 0.001), and specifically can be -0.0001, -0.0002, -0.0003, -0.0004, -0.0005, -0.0006, -0.0007, -0.0008, -0.0009, -0.001, etc., but is not limited to this.

[0180] The value range of d is preferably 0.01 to 0.06, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, etc., but is not limited thereto.

[0181] The value range of e is preferably 0.01 to 0.1, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., but is not limited thereto.

[0182] The value range of f is preferably 0.01 to 0.1, and specifically can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., but is not limited thereto.

[0183] More preferably, x and h satisfy: h = -(0.0001 to 0.001)x 3 +(0.01~0.05)x 2 +(0.02~0.06)x+(0.02~0.06), where the value range of x is 5-30.

[0184] More preferably, x and h satisfy: h = -(0.0002-0.0006)x 3 +(0.01~0.03)x 2 +(0.02~0.04)x+(0.02~0.04), where the value range of x is 6-20.

[0185] In this embodiment, based on Relationship Formula I, in which the total number of welding points and Pad points connecting each welding strip to the gate line is x and the main grid power loss y, Relationship Formula II is established between the total number of welding points and Pad points x connecting each welding strip to the gate line and the warping height h of the half-cell battery. By respectively deriving Relationship Formulas I and II, the value range of x under the preset power loss and the preset warping height range of the half-cell battery is obtained. The welding strip is connected to the gate line through x welding points 40 and Pad points 30.

[0186] In some preferred embodiments, the warping height h is in the range of 0.5 to 7 mm. Further preferably, the warping height h is in the range of 0.5 to 6.2 mm. More preferably, the warping height h is in the range of 0.5 to 5.0 mm.

[0187] Embodiment 9

[0188] An embodiment of the present invention further provides a solar cell system, comprising the solar cell assembly described in any one of the above embodiments 1 to 8.

[0189] In summary, the grid line of the present invention is provided with a plurality of pad points and welding points, each welding strip is connected to the grid line through the pad point, and the welding strip is also connected to the grid line through the welding point. In addition to each welding strip being connected to the solar cell module through the pad point, the present invention adds welding points on the main grid and / or the fine grid, and the welding strip is also connected to the main grid and / or the fine grid through the welding points, which can shorten the carrier transmission distance and reduce the transmission loss.

[0190] Moreover, there is a certain relationship between the number of welding points and the main grid power loss. The welding point is the key component for connecting the positive and negative electrodes inside the battery. Its number will directly affect the transmission path and uniformity of the current inside the battery. The total number of welding points and pad points connecting each welding strip to the grid line is x, and the main grid power loss of the back contact battery is y. When x and y satisfy the following formula I: y = a*x b , which can shorten the carrier transmission distance and reduce the carrier transmission loss. At the same time, it can effectively improve the current uniformity, reduce the internal resistance of the battery, thereby improving the overall performance of the battery and reducing the CTM loss of the component.

[0191] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A solar cell module, characterized in that: including multiple back contact cells and multiple solder strips; The back contact battery comprises a battery substrate and a grid line arranged on the surface of the battery substrate, wherein: The gate line is provided with a plurality of pad points, each welding strip is connected to the gate line through the pad point, and each welding strip is also connected to the gate line through a welding point, wherein the welding point is a non-pad point; The total number of welding points and pad points connected to each welding strip and the grid line is x, and the main grid power loss of the back contact battery is y, and x and y satisfy the following formula I: y = a*x b , a and b are constants.

2. The solar cell assembly according to claim 1, characterized in that: The value range of a is 800-950, the value range of b is -(1-3), and the value range of x is 5-30.

3. The solar cell assembly according to claim 2, characterized in that: x and y satisfy: y = (850 ~ 950) * x -2 ; The value range of x is 6-30, and the value range of y is 1-25w.

4. The solar cell assembly according to claim 3, characterized in that: x and y satisfy: y = (870 ~ 920) * x -2 ; The value range of x is 8-20, and the value range of y is 1.2-15w.

5. The solar cell module according to any one of claims 1 to 4, characterized in that: The total number of welding points and pad points connected to each welding strip and the grid line is x, and the warping height of the half-cell of the back contact battery is h, and x and h satisfy the following formula II: h=cx 3 +dx 2 +ex+f, where c, d, e, and f are constants.

6. The solar cell assembly according to claim 5, characterized in that: The value range of c is -(0.0001~0.001), the value range of d is 0.01~0.06, the value range of e is 0.01~0.1, and the value range of f is 0.01~0.

1.

7. The solar cell assembly according to claim 5, characterized in that: x and h satisfy: h = -(0.0001 ~ 0.001)x 3 +(0.01~0.05)x 2 +(0.02~0.06)x+(0.02~0.06), where the value range of x is 5-30.

8. The solar cell assembly according to claim 7, characterized in that: x and h satisfy: h = -(0.0002 ~ 0.0006)x 3 +(0.01~0.03)x 2 +(0.02~0.04)x+(0.02~0.04), where the value range of x is 6-20.

9. The solar cell assembly according to claim 5, characterized in that: The warping height h ranges from 0.5 to 7 mm.

10. The solar cell assembly according to claim 1, characterized in that: The distance between two adjacent welding points is D, and the value range of D is 3 to 30 mm.

11. The solar cell assembly according to claim 1, characterized in that: The ratio of the number of welding points to Pad points is (1-6):(1-2).

12. The solar cell assembly according to claim 1, characterized in that: The grid lines include a main grid and a fine grid which are arranged crosswise with each other on the surface of the battery substrate, a plurality of pad points are arranged on the main grid, and a plurality of welding points are arranged on the main grid and / or the fine grid; the plurality of welding strips include a first welding strip, the first welding strip is connected to the pad point on the main grid, and the first welding strip is also connected to the main grid and / or the fine grid through welding points.

13. The solar cell assembly according to claim 1, characterized in that: The grid lines include a main grid and a fine grid which are arranged crosswise on the surface of the battery substrate, and a plurality of pad points and welding points are arranged on the fine grid between the main grid closest to the edge of the battery substrate and the edge of the battery substrate; the plurality of welding strips include a second welding strip, the second welding strip is connected to the pad point on the fine grid, and the second welding strip is also connected to the fine grid located between the edge of the battery substrate and the main grid closest to the edge of the battery substrate through welding points.

14. The solar cell assembly according to claim 12 or 13, characterized in that: The welding points are fixed points formed after screen printing.

15. The solar cell assembly according to claim 12 or 13, characterized in that: The shape of the welding point is one or more of a cube, a cuboid, a sphere, a cylinder, a cone, and a prism.

16. The solar cell assembly according to claim 12 or 13, characterized in that: The projection area of ​​the welding point on the battery substrate is 0.1 square millimeters to 1.5 square millimeters.

17. The solar cell assembly according to claim 12 or 13, characterized in that: Two adjacent welding points are arranged at equal intervals.

18. The solar cell assembly according to claim 12 or 13, characterized in that: The welding points are one or more of solder paste points, silver paste points, copper paste points, and silver-copper points.

19. The solar cell assembly according to claim 1, characterized in that: Each of the soldering strips is connected to the pad point via a metal layer.

20. The solar cell assembly according to claim 19, characterized in that The metal layer is one or more of a solder paste layer, a silver paste layer, a copper paste layer, and a silver-copper paste layer.

21. The solar cell assembly according to claim 1, characterized in that The welding points include a first welding point and a second welding point, the first welding point is located at two ends of the main grid, and the second welding point is located between the first welding points.

22. The solar cell assembly according to claim 21, characterized in that The area of ​​the first welding point is smaller than the area of ​​the second welding point.

23. The solar cell assembly according to claim 22, characterized in that: The area of ​​the first welding point is 0.1 square millimeters to 1.0 square millimeters, and the area of ​​the second welding point is 0.5 square millimeters to 1.5 square millimeters.

24. The solar cell assembly according to claim 1, characterized in that The Pad points include a first Pad point and a second Pad point, the first Pad point is located at two ends of the main grid, and the second Pad point is located between the first Pad points.

25. The solar cell assembly according to claim 24, characterized in that: The area of ​​the first Pad point is greater than the area of ​​the second Pad point.

26. A solar cell system, characterized in that: Comprising a solar cell module assembly as described in any one of claims 1-25.

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