Back contact solar cell, photovoltaic module and photovoltaic system

Abstract

The utility model provides a back contact solar cell, a photovoltaic assembly and a photovoltaic system, and relates to the field of photovoltaic technology. The back contact solar cell comprises an electrode structure, and the electrode structure comprises a plurality of aluminum electrode grid lines; the aluminum electrode grid line comprises an aluminum substrate and aluminum thorns; the aluminum thorns are positioned at the upper part of the aluminum electrode grid line; the insulating glue is positioned on the aluminum electrode grid line and covers the aluminum thorns; and the height of the aluminum thorns is less than or equal to 6 microns. In the embodiment of the utility model, the height of the aluminum thorns is very small, and the thickness of the insulation paste is also very small, so that the warping degree of the back contact solar cell is greatly reduced, and the merging risk of a photovoltaic module formed by the back contact solar cell is also greatly reduced. Meanwhile, the height of the aluminum thorns is very small, the use amount of aluminum electrode slurry can be reduced, the thickness of the insulation paste is very small, the use amount of the insulation paste is greatly reduced, and therefore the cost is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaics, in particular to a back-contact solar cell, a photovoltaic component and a photovoltaic system. Background Art

[0002] The electrode structure of the back-contact solar cell is on the backlight side of the cell, and there is no electrode blocking the light-facing side, so it has a higher short-circuit current and photoelectric conversion efficiency. Compared with silver, the cost of aluminum is lower, so aluminum electrode grid lines are usually set in the electrode structure of the back-contact solar cell.

[0003] However, due to the material properties of aluminum, the aluminum electrode grid lines usually have aluminum spikes. In order to avoid short circuits, insulating glue is usually provided on the aluminum electrode grid lines.

[0004] However, in the current electrode structure of the back-contact solar cell, the thickness of the insulating glue is too large, which will cause the back-contact solar cell to generally have a large warping. If the warping is too large, there will be a risk of paralleling during the process of forming a photovoltaic module. Utility Model Content

[0005] The utility model provides a back-contact solar cell, a photovoltaic module and a photovoltaic system, aiming to solve the problem of high risk of photovoltaic modules formed by existing back-contact solar cells.

[0006] In a first aspect of the present invention, a back-contact solar cell is provided, wherein the electrode structure comprises:

[0007] A plurality of aluminum electrode grid lines; the aluminum electrode grid lines include an aluminum substrate and aluminum spikes, and the aluminum spikes are located on the upper part of the aluminum electrode grid lines;

[0008] and an insulating glue located on the aluminum electrode grid wire and covering the aluminum thorns;

[0009] Wherein, the height of the aluminum thorns is less than or equal to 6 μm.

[0010] In the embodiment of the utility model, the height of the aluminum spike is less than or equal to 6μm. Compared with the related art, the height of the aluminum spike is more than ten microns, or even eighty or ninety microns. In the present application, the height of the aluminum spike is very small. Since the insulating glue needs to cover the aluminum spike, in the related art, the height of the aluminum spike is too large, which will either cause the thickness of the insulating glue to be very large, resulting in serious warping of the back-contact solar cell and easy paralleling of the photovoltaic module; or the aluminum spike will easily pierce the insulating glue and cause a short circuit of the cell. In the present application, the height of the aluminum spike is very small, and thus the thickness of the insulating glue is also very small, which greatly reduces the degree of warping of the back-contact solar cell.

[0011] The risk of photovoltaic modules formed by the back-contact solar cells is also greatly reduced; and the problem of short circuit of the cells caused by aluminum spikes can also be reduced. At the same time, the height of the aluminum spikes is very small, which can also reduce the amount of aluminum electrode slurry used, and because the thickness of the insulating glue is also very small, the amount of insulating glue used is greatly reduced. Therefore, the present application also greatly reduces the cost.

[0012] Optionally, the aluminum thorn includes: a first aluminum thorn and a second aluminum thorn, and the height of the first aluminum thorn is greater than or equal to the height of the second aluminum thorn;

[0013] A difference between a height of the first aluminum thorn and a height of the second aluminum thorn is greater than or equal to 0 and less than or equal to 6 μm.

[0014] Optionally, the aluminum electrode grid lines are aluminum bus grid lines, and the ratio of the total height to the width of the aluminum bus grid lines is greater than or equal to 0.15 and less than or equal to 0.22; and / or,

[0015] The aluminum electrode grid lines are aluminum collector grid lines, and the ratio of the total height to the width of the aluminum collector grid lines is greater than or equal to 0.27 and less than or equal to 0.73.

[0016] Optionally, the aluminum electrode grid line is an aluminum bus grid line, and the ratio of the thickness of the insulating glue covering the entire aluminum bus grid line to the total height of the aluminum bus grid line is greater than or equal to 1.04 and less than or equal to 1.74; and / or,

[0017] The aluminum electrode grid line is an aluminum collector grid line, and the ratio of the thickness of the insulating glue covering the entire aluminum collector grid line to the total height of the aluminum collector grid line is greater than or equal to 1.06 and less than or equal to 2.52.

[0018] Optionally, the height of the aluminum spike is less than or equal to 4 μm; and / or the insulating glue is 8 μm to 17 μm higher than the aluminum spike.

[0019] Optionally, the insulating glue is 10 μm to 13 μm higher than the aluminum thorn.

[0020] Optionally, the aluminum electrode grid line is an aluminum bus grid line, the height of the aluminum substrate of the aluminum bus grid line is 19μm to 25μm, the width of the aluminum bus grid line is 115μm to 132μm; the thickness of the insulating glue covering the entire aluminum bus grid line is 25um to 42um.

[0021] Optionally, the aluminum electrode grid line is an aluminum collector grid line, the height of the aluminum substrate of the aluminum collector grid line is 9.55μm to 16μm, the width of the aluminum collector grid line is 22μm to 35μm; the thickness of the insulating glue covering the entire aluminum collector grid line is 19μm to 33um.

[0022] Optionally, the back contact solar cell comprises: a substrate, the electrode structure is located on the backlight side of the substrate, the length of the substrate is 91 mm to 107 mm, and the width of the substrate is 182.2±1 mm; and / or,

[0023] In the back contact solar cell, the weight of the insulating glue is 350 mg to 400 mg.

[0024] Optionally, the back-contact solar cell is placed on a carrying platform, and when the light-facing surface at least partially contacts the carrying platform and the back-to-light surface faces away from the carrying platform, the warping of the back-contact solar cell is less than or equal to 3 mm.

[0025] A second aspect of the present invention provides a photovoltaic assembly, comprising: a plurality of any of the aforementioned back-contact solar cells.

[0026] A third aspect of the present invention provides a photovoltaic system, comprising: a plurality of the aforementioned photovoltaic components.

[0027] The above-mentioned back-contact solar cell, photovoltaic module and photovoltaic system have the same or similar beneficial effects, and will not be described in detail here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figures 1 to 3 3D microscope images of three types of back-contact solar cells in the related art are shown;

[0030] Figure 4 A photographic image of a local electrode structure of a back contact solar cell in the related art is shown;

[0031] Figure 5 A photographic image showing a local electrode structure of a back contact solar cell in an embodiment of the present utility model;

[0032] Figure 6 A schematic diagram of the warpage of a back-contact solar cell in an embodiment of the utility model is shown.

[0033] Description of the accompanying drawings:

[0034] 21-back contacts the backlight side of the solar cell, 22-back contacts the light-facing side of the solar cell. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] In the electrode structure of the existing back-contact solar cell, the main reason for the excessive thickness of the insulating glue is that the size of the aluminum thorns is large or the height is large. For example, the height of the aluminum thorns is more than ten microns, or even eighty or ninety microns, and the height difference is large. In order to avoid short circuits, the insulating glue needs to completely cover all the aluminum thorns. On the one hand, due to the large size or height of the aluminum thorns, thicker insulating glue is required. On the other hand, due to the large size or height difference of the aluminum thorns, the insulating glue needs to cover the aluminum thorns with the largest size or height, which also increases the thickness of the insulating glue. At the same time, the linear expansion coefficient of the insulating glue is about 20 times that of the linear expansion coefficient of the substrate (such as a silicon substrate). The thickness of the insulating glue is large, which will inevitably cause a large degree of warping of the back-contact solar cell. If the warping is too large, there will be a high risk of paralleling in the process of forming photovoltaic modules. At the same time, the size of the aluminum thorns is too large, and the aluminum thorns will also consume a lot of aluminum electrode slurry. In addition, the thickness of the insulating glue is large, and the amount of insulating glue used is large, which also leads to high costs.

[0037] For example, refer to Figures 1 to 4 , Figure 1 It is a 3D microscope image looking up or down. Figure 1 Medium magnification is 5x. Figure 2 The 3D microscope image in the middle is based on the aluminum busbar line. Figure 3 This is a 3D microscope image with the collector grid line as the main viewing angle. Figure 2 and Figure 3 The medium magnification is 50 times. Figure 1 In the figure, the brighter ones on the left and right sides are the collector grid lines, the collector grid line in the middle in the vertical direction is the silver collector grid line, and the ones on both sides are the aluminum collector grid lines. Figure 1 It can be concluded that the density of aluminum collector grid lines is not as good as that of silver collector grid lines, so there are more aluminum thorns on the aluminum electrode grid lines. Figure 2 and Figure 3 The part extending in the up and down direction is the aluminum busbar line. The protruding spikes in the aluminum busbar line are aluminum spikes. The size of the aluminum spikes is large or the height is large, and it is uncontrolled, with a large height difference. Figure 2 Figure 3In the figure, the upper and brighter part is the silver collector grid line, and the aluminum collector grid line is basically distributed in line with the silver collector grid line, and the aluminum collector grid line is covered with insulating glue. Figure 4 This is a photo of the aluminum electrode grid line. Figure 4 The sharp thorns are aluminum thorns. Figure 4 The size of the aluminum spikes is larger or the height is larger, and they are uncontrolled, with a large height difference.

[0038] The utility model provides a back-contact solar cell, wherein the electrode structure of the back-contact solar cell is located on the backlight side. During the normal operation of the back-contact solar cell, the surface that mainly receives light is the light-facing side, and the backlight side and the light-facing side are opposite. The electrode structure is used to derive current.

[0039] The specific type of the solar cell is not limited. For example, the solar cell may be a HPBC (hybrid passivated back contact cell).

[0040] The electrode structure may include: a plurality of aluminum electrode grid lines, where the aluminum electrode grid lines can be used as positive electrodes or negative electrodes. There is no specific limitation on the number of aluminum electrode grid lines. The aluminum electrode grid lines include an aluminum substrate and aluminum thorns, and the aluminum thorns are located on the upper part of the aluminum electrode grid lines. The aluminum thorns are caused by processing technology and other reasons, and basically do not improve the battery performance, and will bring short circuit risks. In order to avoid short circuits, the electrode structure also includes: an insulating glue located on the aluminum electrode grid lines and covering the aluminum thorns. The height of the aluminum thorns is less than or equal to 6μm, and the direction of the height of the aluminum thorns is along the extension direction of the aluminum thorns. That is, in the electrode structure, the height of any aluminum thorn is less than or equal to 6μm. Compared with the height of the aluminum thorns in the related art, the height of the aluminum thorns in the present application is very small, so only a thin insulating glue is needed to cover the aluminum thorns. Therefore, the thickness of the insulating glue is also very small, which greatly reduces the warping degree of the back contact solar cell, and the risk of photovoltaic modules formed by the back contact solar cell is also greatly reduced; and it can also reduce the problem of short circuit of the battery cell caused by the aluminum thorns. At the same time, the height of the aluminum thorn is very small, which can also reduce the amount of aluminum electrode slurry used. Moreover, since the thickness of the insulating glue is also very small, the amount of insulating glue used is greatly reduced. Therefore, the present application also greatly reduces the cost.

[0041] For example, in the electrode structure, the height of any aluminum spike can be 6 μm, or 5.8 μm, or 5.6 μm, or 5 μm, or 4.3 μm, or 4.1 μm, or 3 μm, or 2.6 μm, or 2 μm, or 1.4 μm, or 1 μm, or 0.3 μm. Alternatively, in the electrode structure, some aluminum electrode grid lines have no aluminum spikes at all.

[0042] Optionally, the aluminum spikes in the electrode structure include: a first aluminum spike and a second aluminum spike, and the height of the first aluminum spike is greater than or equal to the height of the second aluminum spike, that is, the first aluminum spike is an aluminum spike with a higher height. When the heights of all aluminum spikes are not completely equal, the first aluminum spike can be any aluminum spike in the electrode structure except the aluminum spike with the lowest height. When the heights of all aluminum spikes are completely equal, the first aluminum spike can be any aluminum spike in the electrode structure. The second aluminum spike is an aluminum spike with a lower height. When the heights of all aluminum spikes are not completely equal, the second aluminum spike can be any aluminum spike in the electrode structure except the aluminum spike with the highest height. When the heights of all aluminum spikes are completely equal, the second aluminum spike can be any aluminum spike in the electrode structure. The difference between the height of the first aluminum spike and the height of the second aluminum spike is greater than or equal to 0 and less than or equal to 6μm. That is, in the electrode structure, any

[0043] The absolute value of the difference between the heights of the two aluminum spikes is within the range of 0 to 6um, the heights of the aluminum spikes are relatively uniform, and the height differences of the aluminum spikes are small. Furthermore, the height of the aluminum spike with the largest height is not too large, and the insulating glue covers the aluminum spike with the largest height, that is, covers all the aluminum spikes. Therefore, only a thin insulating glue is needed to cover the aluminum spikes. Therefore, the thickness of the insulating glue is also very small, which greatly reduces the warping degree of the back-contact solar cell, and the risk of photovoltaic modules formed by the back-contact solar cell is also greatly reduced; and the problem of short circuit of the battery cell caused by the aluminum spikes can also be reduced. At the same time, the height of the aluminum spikes is very small, which can also reduce the amount of aluminum electrode slurry used, and because the thickness of the insulating glue is also very small, the amount of insulating glue used is greatly reduced. Therefore, the present application also greatly reduces the cost.

[0044] For example, in the electrode structure, the difference between the height of the first aluminum spike and the height of the second aluminum spike can be 6μm, or 5.8μm, or 5.6μm, or 5μm, or 4.3μm, or 4.1μm, or 3.7μm, or 3μm, or 2.6μm, or 2μm, or 1.4μm, or 1μm, or 0.3μm. For another example, when the heights of all aluminum spikes are completely equal, the difference between the height of the first aluminum spike and the height of the second aluminum spike is 0.

[0045] For example, refer to Figure 5 , Figure 5 This is a photo of the aluminum electrode grid line, relative to Figure 4 In terms of Figure 5 The size of the aluminum spikes is smaller or the height is smaller, and the size or height distribution of the aluminum spikes is more uniform.

[0046] Optionally, the aluminum electrode grid line is an aluminum bus grid line, which is used to derive current. The ratio of the total height of the aluminum bus grid line (i.e., the sum of the heights of the aluminum base and aluminum spikes of the aluminum bus grid line) to its width is greater than or equal to 0.15 and less than or equal to 0.22. The direction of the width of the aluminum bus grid line is perpendicular to the direction of the total height of the aluminum bus grid line and the extension direction of the aluminum bus grid line. Compared with the related art, in the present application, the aspect ratio of the aluminum bus grid line is larger, that is, the aluminum bus grid line is taller and narrower, the shading is smaller, the light absorption area is larger, and the current collection efficiency is higher. It should be noted that the total height of the aluminum bus grid line mentioned in the full text of this application refers to the sum of the heights of the aluminum base and aluminum spikes of the aluminum bus grid line.

[0047] For example, the ratio of the total height of the aluminum busbar line to its width may be: 0.15, or 0.154, or 0.16, or 0.17, or 0.181, or 0.186, or 0.19, or 0.2, or 0.21, or 0.22.

[0048] Optionally, the aluminum electrode grid line is an aluminum bus grid line, and the ratio of the thickness of the insulating glue covering the entire aluminum bus grid line, that is, covering the aluminum base and aluminum thorns of the aluminum bus grid line, to the total height of the aluminum bus grid line (that is, the sum of the height of the aluminum base and the aluminum thorns of the aluminum bus grid line) is greater than or equal to 1.04 and less than or equal to 1.74, and the direction of the thickness of the insulating glue can be parallel to the extension direction of the aluminum thorns in the aluminum bus grid line. For example, the direction of the height of the aluminum bus grid line is parallel to the extension direction of the aluminum thorns in the aluminum bus grid line, then, the direction of the thickness of the insulating glue is parallel to the direction of the height of the aluminum bus grid line. On the one hand, the height of the aluminum thorns in the aluminum bus grid line is small, and on the other hand, the height distribution of the aluminum thorns of the aluminum bus grid line is relatively uniform. Therefore, in the present application, the thickness of the insulating glue covering the entire aluminum bus grid line is relatively small compared to the total height of the aluminum bus grid line, that is, the thickness of the insulating glue covering the aluminum base and the aluminum thorns is small, which can not only reduce warping, but also reduce costs. It should be noted that the thickness of the insulating glue covering the entire aluminum bus grid mentioned in the full text refers to: along the direction of the thickness, starting from the position of the insulating glue covering the entire aluminum bus grid that is adjacent to the backlight surface of the back contact solar cell (generally the bottom of the aluminum bus grid), to the maximum size of the insulating glue covering the entire aluminum bus grid that is away from the backlight surface of the back contact solar cell. The total height of the aluminum bus grid here can refer to the total size of the aluminum bus grid along the extension direction of the aluminum spikes. For example, if the aluminum spikes extend along the height direction of the aluminum bus grid, the total height of the aluminum bus grid is the total size of the aluminum base and the aluminum spikes of the aluminum bus grid along the height direction of the aluminum bus grid. For example, the ratio of the thickness of the insulating glue covering the entire aluminum bus bar to the total height of the aluminum bus bar may be 1.04, or 1.09, or 1.16, or 1.27, or 1.381, or 1.486, or 1.59, or 1.65, or 1.721, or 1.73, or 1.74.

[0049] Optionally, the height of the aluminum substrate of the aluminum bus grid line is 19 μm to 25 μm, and the width of the aluminum bus grid line is 115 μm to 132 μm. Compared with the related art, in which the height of the aluminum substrate of the aluminum bus grid line is 15 μm to 19 μm, and the width of the aluminum bus grid line is 130 μm to 132 μm, in the present application, the aluminum substrate of the aluminum bus grid line is taller and narrower, with less shading, a larger light absorption area, and higher current collection efficiency.

[0050] That is, the height of the aluminum substrate of the aluminum bus bar line may be a set of [19 μm, 25 μm]. For example, the height of the aluminum substrate of the aluminum bus bar line may be 19 μm, or 19.1 μm, or 19.8 μm, or 20.6 μm, or 20.9 μm, or 21.3 μm, or 22.1 μm, or 22.7 μm, or 23 μm, or 23.2 μm, or 23.74 μm, or 24.3 μm, or 25 μm.

[0051] That is, the width of the aluminum busbar lines may be a set of [115 μm, 132 μm]. The width of the aluminum busbar lines may also be 115 μm to 122 μm. For example, the width of the aluminum busbar lines may be 115 μm, or 115.8 μm, or 116.6 μm, or 117 μm, or 118.3 μm, or 118.5 μm, or 119.7 μm, or 120 μm, or 120.2 μm, or 120.74 μm, or 121.3 μm,

[0052] Or 122μm, or 123.2μm, or 125μm, or 130μm, or 132μm.

[0053] Optionally, the thickness of the insulating glue covering the entire aluminum bus grid line (i.e., covering the aluminum base and aluminum thorns of the aluminum bus grid line) can be 25um to 42um. Specifically, the height of the aluminum base of the aluminum bus grid line is 19μm to 25μm, and the height of the aluminum thorns in the aluminum bus grid line is less than or equal to 6μm. When the height of the aluminum base of the aluminum bus grid line and the height of the aluminum thorns are both maximized, the height of the two is 25+6=31μm, that is, the total height of the aluminum bus grid line is 31μm at most. In order to avoid short circuits as much as possible, a certain safety thickness is reserved in addition to the total height. Therefore, the thickness of the insulating glue covering the entire aluminum bus grid line is 25um to 42um, which can not only greatly reduce the risk of short circuits, but also the thickness of the insulating glue will not be wasted, and the degree of warping of the back contact solar cell is reduced. The thickness of the insulating glue covering the entire aluminum bus grid line can also be less than or equal to 33um. When the height of the aluminum base of the aluminum bus grid line and the height of the aluminum thorns are both maximized, the height of the two is 25+6=31μm. In order to avoid short circuit as much as possible, in addition to the total height, a safety thickness of 1μm to 2μm is reserved. When the safety thickness is also taken to the maximum, it is 31+2=33μm. Therefore, the thickness of the insulating glue covering the entire aluminum busbar is less than or equal to 33um, which can not only greatly reduce the risk of short circuit, but also save materials to a greater extent and reduce the degree of warping of the back contact solar cell. The definition of the thickness of the insulating glue covering the entire aluminum busbar here refers to the above record, and it will not be repeated here to avoid repetition.

[0054] For example, the thickness of the insulating glue covering the entire aluminum bus bar can be 42μm, or 40.8μm, or 37.6μm, or 34.2μm, or 33μm, or 32.8μm, or 30.6μm, or 29.9μm, or 28.3μm, or 27.7μm, or 27.1μm, or 26μm, or 25.2μm, or 25μm.

[0055] Optionally, the aluminum electrode grid line is an aluminum collector grid line, and the ratio of the total height of the aluminum collector grid line (i.e., the sum of the height of the aluminum base and aluminum spikes of the aluminum collector grid line) to the width is greater than or equal to 0.27 and less than or equal to 0.73. The direction of the width of the aluminum collector grid line, the direction of the total height of the aluminum collector grid line, and the extension direction of the aluminum collector grid line are all perpendicular. Compared with the related art, in the present application, the aspect ratio of the aluminum collector grid line is larger, that is, the aluminum collector grid line is taller and narrower, the shading is smaller, the light absorption area is larger, and the current collection efficiency is higher. It should be noted that in the full text of this application, the total height of the aluminum collector grid line mentioned refers to the sum of the height of the aluminum base and aluminum spikes of the aluminum collector grid line.

[0056] For example, the ratio of the total height to the width of the aluminum collector grid line can be: 0.27, or 0.284, or 0.3, or 0.37, or 0.481, or 0.586, or 0.61, or 0.69, or 0.71,

[0057] Or 0.72, or 0.73.

[0058] Optionally, the aluminum electrode grid line is an aluminum collector grid line. The ratio of the thickness of the insulating glue covering the entire aluminum collector grid line (i.e., the aluminum substrate and aluminum thorns covering the aluminum collector grid line) to the total height of the aluminum collector grid line is greater than or equal to 1.06 and less than or equal to 2.52. The direction of the thickness of the insulating glue can be parallel to the extension direction of the aluminum thorns of the aluminum collector grid line. For example, the direction of the height of the aluminum collector grid line is parallel to the extension direction of the aluminum thorns on the aluminum collector grid line. Then, the direction of the thickness of the insulating glue is parallel to the direction of the height of the aluminum collector grid line. On the one hand, the height of the aluminum thorns in the aluminum collector grid line is relatively small. On the other hand, the height distribution of the aluminum thorns on the aluminum collector grid line is relatively uniform. Therefore, in the present application, the thickness of the insulating glue covering the entire aluminum collector grid line is relatively small compared to the total height of the aluminum collector grid line, that is, the thickness of the insulating glue covering the entire aluminum collector grid line is relatively small, which can not only reduce warping, but also reduce costs. It should be noted that the thickness of the insulating glue covering the entire aluminum collector grid mentioned in the full text refers to: along the direction of the thickness, starting from the position of the insulating glue covering the entire aluminum collector grid that is adjacent to the backlight surface of the back-contact solar cell (generally the bottom of the aluminum collector grid), to the maximum size of the position of the insulating glue covering the entire aluminum collector grid away from the backlight surface of the back-contact solar cell. The total height of the aluminum collector grid here may refer to the total size of the aluminum collector grid along the extension direction of the aluminum spikes. For example, if the aluminum spikes extend along the height direction of the aluminum collector grid, the total height of the aluminum collector grid is the total size of the aluminum base and the aluminum spikes of the aluminum collector grid along the height direction of the aluminum collector grid.

[0059] For example, the ratio of the thickness of the insulating glue covering the entire aluminum collector grid line to the total height of the aluminum collector grid line can be 1.06, or 1.09, or 1.16, or 1.27, or 1.381, or 1.486, or 1.59, or 1.65, or 1.72, or 1.83, or 1.99, or 2, or 2.32, or 2.52.

[0060] Optionally, the height of the aluminum substrate of the aluminum collector grid line is 9.55 μm to 16 μm, and the width of the aluminum collector grid line is 22 μm to 35 μm. Compared with the related art, in which the height of the aluminum substrate of the aluminum collector grid line is 9.4 μm to 9.55 μm, and the width of the aluminum collector grid line is 37 μm to 45 μm, in the present application, the aluminum substrate of the aluminum collector grid line is taller and narrower, with less shading, a larger light absorption area, and higher current collection efficiency.

[0061] That is, the height of the aluminum substrate of the aluminum collector grid line may be a set of [9.55 μm, 16 μm]. For example, the height of the aluminum substrate of the aluminum collector grid line may be 9.55 μm, or 9.8 μm, or 10.6 μm, or

[0062] Or 10.9μm, or 11.3μm, or 12.1μm, or 12.52μm, or 13μm, or 13.2μm, or 14.74μm, or 15.3μm, or 16μm.

[0063] That is, the width of the aluminum collector grid line may be a set of [22μm, 35μm]. For example, the width of the aluminum collector grid line may be 22μm, or 22.8μm, or 23.6μm, or 24μm, or 25.3μm, or 28.5μm, or 29.7μm, or 30μm, or 30.2μm, or 31.74μm, or 32.3μm, or 33μm, or 34.7μm, or 35μm.

[0064] Optionally, the thickness of the insulating glue covering the entire aluminum collector grid line is 19μm to 33μm. Specifically, the height of the aluminum substrate of the aluminum collector grid line is greater than or equal to 9.55μm and less than or equal to 16μm. The height of the aluminum thorns on the aluminum collector grid line is less than or equal to 6μm. When the height of the aluminum substrate of the aluminum collector grid line and the height of the aluminum thorns are both maximized, the heights of the two are 16+6=22μm, that is, the total height of the aluminum collector grid line is 22μm at most. In order to avoid short circuits as much as possible, a safety thickness is reserved in addition to the total height. Therefore, the thickness of the insulating glue covering the entire aluminum collector grid line is 19μm-33um, which can not only greatly reduce the risk of short circuits, but also the thickness of the insulating glue will not be wasted, reducing the degree of warping of the back contact solar cell. The thickness of the insulating glue covering the entire aluminum collector grid line can also be less than or equal to 24um. When the height of the aluminum substrate of the aluminum collector grid line and the height of the aluminum thorns are both maximized, the heights of the two are 16+6=22μm. In order to avoid short circuit as much as possible, in addition to the total height, a safety thickness of 1μm to 2μm is reserved. When the safety thickness is also taken to the maximum, it is 22+2=24μm. Therefore, the thickness of the insulating glue covering the entire aluminum collector grid line is less than or equal to 24um, which can not only greatly reduce the risk of short circuit, but also can greatly avoid material waste and reduce the degree of warping of the back contact solar cell. The definition of the thickness of the insulating glue covering the entire aluminum collector grid line here refers to the above record, and it will not be repeated here to avoid repetition.

[0065] For example, the thickness of the insulating glue covering the entire aluminum current collecting grid line can be 33μm, or 32μm, or 31.8μm, or 30μm, or 27.3μm, or 26μm, or 25μm, or 24μm, or 23.8μm, or 23.6μm, or 22.9μm, or 21.3μm, or 20.7μm, or 19.1μm, or 19μm.

[0066] Optionally, the height of the aluminum thorn is less than or equal to 4 μm. The height of the aluminum thorn is very small, so only a thin insulating glue is needed to cover the aluminum thorn. Therefore, the thickness of the insulating glue is also very small, which greatly reduces the warping degree of the back-contact solar cell, and the risk of photovoltaic modules formed by the back-contact solar cell is also greatly reduced; and the problem of short circuit of the cell caused by the aluminum thorn can also be reduced. At the same time, the height of the aluminum thorn is very small, which can also reduce the amount of aluminum electrode slurry used, and because the thickness of the insulating glue is also very small, the amount of insulating glue used is greatly reduced. Therefore, the present application also greatly reduces the cost.

[0067] For example, in this electrode structure, the height of any aluminum thorn can be 4μm, or 3.7μm, or 3.6μm, or 3.5μm, or 3μm, or 2.7μm, or 2.4μm, or 2μm, or 1.9μm, or 1.6μm, or 1.5μm, or 1μm, or 0.7μm, or 0.55μm, or 0.3μm.

[0068] Optionally, the insulating glue is 8μm to 17μm higher than the aluminum stab, that is, the insulating glue is 8μm to 17μm higher than the highest point of the aluminum stab in the aluminum electrode grid line, and the extra 8μm to 17μm is used as a safety thickness or a safety distance. The distance that the insulating glue is higher than the aluminum stab is set appropriately, which can not only significantly reduce the risk of short circuit, but also avoid waste of insulating glue, etc., and reduce the degree of warping of back-contact solar cells.

[0069] For example, the insulating glue is 8μm, or 8.5μm, or 9μm, or 9.3μm, or 10μm, or 10.1μm, or 10.6μm, or 11.3μm, or 12.5μm, or 13μm, or 13.4μm, or 14μm, or 14.6μm, or 15μm, or 15.5μm, or 16μm, or 16.5μm, or 17μm higher than the aluminum thorn.

[0070] Optionally, the insulating glue is 10μm to 13μm higher than the aluminum stab, that is, the insulating glue is 10μm to 13μm higher than the highest point of the aluminum stab on the aluminum electrode grid line, and the extra 10μm to 13μm is used as a safety thickness or a safety distance. The distance that the insulating glue is higher than the aluminum stab is more appropriately set, which can not only significantly reduce the risk of short circuit, but also avoid waste of insulating glue, etc., and reduce the degree of warping of back-contact solar cells.

[0071] For example, the insulating glue is 10μm, or 10.1μm, or 10.23μm, or 10.5μm, or 10.6μm, or 11μm, or 11.3μm, or 11.7μm, or 11.84μm, or 12μm, or 12.16μm, or 12.42μm, or 12.5μm, or 12.8μm, or 13μm higher than the aluminum thorn.

[0072] It should be noted that the insulating glue mentioned in the full text can be green glue or the like, which is a glue that can play an insulating role in the electrode structure of the back contact solar cell.

[0073] The utility model also provides an aluminum electrode slurry, which is used to prepare the aluminum electrode grid lines in any of the aforementioned electrode structures of the back contact solar cells. The diameter of the particles in the aluminum electrode slurry is less than or equal to 10um. Compared with the diameter of the particles in the aluminum electrode slurry in the related art, which is about 25um, the diameter of the particles in the aluminum electrode slurry in the present application is smaller, and the plasticity of the aluminum electrode grid lines is better, thereby effectively controlling the size or height of the aluminum spikes in the formed aluminum electrode grid lines, thereby greatly reducing the thickness of the insulating glue, reducing the warping of the back contact solar cell, ensuring the stability and yield of the photovoltaic module process, and reducing the cost.

[0074] For example, the diameter of the particles in the aluminum electrode slurry can be 10um, or 9.93μm, or 9.8μm, or 9.5μm, or 9.3μm, or 8.7μm, or 8.4μm, or 8μm, or 7.2μm, or 6.74μm, or 5.3μm, or 5.1μm, or 5μm, or 4.98μm, or 4.3μm, or 4.1μm, or 3.7μm, or 3μm, or 2.2μm.

[0075] It should be noted that the mass content of aluminum in the aluminum electrode slurry can reach 70% to 80%, or even 90% or more. The aluminum electrode slurry can be understood as pure aluminum slurry, and the aluminum electrode slurry may contain some organic adhesive, the mass ratio of the organic adhesive may be 5% to 20%, and the organic adhesive can provide certain adhesion and high temperature resistance. The aluminum electrode slurry may also contain some metal impurities. The specific composition of the aluminum electrode slurry is not specifically limited.

[0076] The back-contact solar cell further includes: a substrate, wherein the electrode structure of any of the aforementioned back-contact solar cells is located on the backlight side of the substrate, and the substrate may be a silicon substrate, etc., and the material of the substrate is not specifically limited.

[0077] Optionally, the length of the substrate is 91mm (millimeter) to 107mm, the width of the substrate is 182.2±1mm, and / or, in the back-contact solar cell, the weight of the insulating glue is 350mg (milligrams) to 400mg. When the substrate size is equal, in the related art, the weight of the insulating glue in the back-contact solar cell is 480mg to 500mg or even heavier. Compared with the related art, the weight of the insulating glue in the back-contact solar cell is lighter, that is, the thickness of the insulating glue is thinner, which reduces the warping of the back-contact solar cell, ensures the stability and yield of the photovoltaic module process, and reduces the cost.

[0078] For example, the length of the substrate is 91 mm, or 91.5 mm, or 91.6 mm, or 92 mm, or 92.5 mm, or 92.75 mm, or 93 mm, or 93.5 mm, or 94 mm, or 94.5 mm, or 95 mm, or 95.5 mm, or 95.75 mm, or 96 mm, or 96.5 mm, or 96.75 mm, or 97 mm, or 97.5 mm, or 97.75 mm, or 98 mm, or 98.5 mm, or 98.75 mm, or 99 mm, or 99.5 mm, or 100 mm, or 100.5 mm, or 101mm, or 101.5mm, or 102mm, or 102.5mm, or 103mm, or 103.5mm, or 104mm, or 104.5mm, or 105mm, or 105.5mm, or 106mm, or 106.5mm, or 107mm, the width of the substrate is 182.2±1mm, and the weight of the insulating glue in the back contact solar cell can be 350mg, or 352mg, or 359mg, or 360mg, or 372mg, or 387mg, or 388.2mg, or 391.2mg, or 395mg, or 400mg.

[0079] It should be noted that the weight of the insulating glue in the back-contact solar cell can also be called the wet weight of the insulating glue in the back-contact solar cell.

[0080] Figure 6In the figure, the x-axis represents the support platform or the first surface of the support platform supporting the back-contact solar cell. The y-axis represents the warping diagram of the back-contact solar cell. For the back-contact solar cell, the inventors found that since the electrodes of the back-contact solar cell are all arranged on the backlight surface 21, and the linear expansion coefficient of the functional layers such as the material of the electrode part and the insulating glue is greatly different from the linear expansion coefficient of the silicon substrate, the back-contact solar cell is warped toward the backlight surface 21. The shape of the formed back-contact solar cell is always that the backlight surface 21 is more contracted inward. In the process of placing the back-contact solar cell, the light-facing surface 22 of the back-contact solar cell is at least partially in contact with the support platform, and the backlight surface 21 of the back-contact solar cell is away from the support platform. In this case, several corners of the back-contact solar cell are warped, and the middle part contacts the support platform. Since the several raised corners of the back-contact solar cell basically do not touch the supporting platform and are basically not affected by the friction of the supporting platform, the back-contact solar cell can fully stretch naturally, so that the stress of the electrodes, insulating glue, etc. in the back-contact solar cell can be completely released. Therefore, the warping degree obtained in this way is basically consistent with the actual warping degree of the back-contact solar cell.

[0081] The back contact solar cell of the present invention refers to Figure 6 The back-contact solar cell is placed on a carrier platform, and when the light-facing surface 22 at least partially contacts the carrier platform and the back-light surface 21 is away from the carrier platform, the warpage of the back-contact solar cell is less than or equal to 3 mm. Figure 6 The warpage display method shown, since the obtained warpage is basically consistent with the actual warpage, the back-contact solar cells with unqualified warpage will basically not be laminated together. During the lamination process, the back-contact solar cell cells with a warpage less than or equal to 3mm will basically not be stacked together, thereby improving the qualified rate of photovoltaic modules.

[0082] For example, when the back-contact solar cell is placed on a carrying platform, with the light-facing surface 22 at least partially contacting the carrying platform and the back-light surface 21 away from the carrying platform, the warping of the back-contact solar cell can be: 3 mm, or 2.9 mm, or 2.5 mm, or 2 mm, or 1.95 mm, or 1.6 mm, or 1.7 mm, or 1 mm.

[0083] The distance between at least two angular positions of the light-facing surface 22 of the back-contact solar cell and the first surface can reflect the degree of warping of the back-contact solar cell. The larger the distance, the greater the degree of warping. Therefore, at least two angular positions of the light-facing surface 22 of the back-contact solar cell and at least two distances between the first surface can accurately reflect the warping of the back-contact solar cell. The warping is more consistent with the actual warping of the back-contact solar cell, which can better control the quality of the back-contact solar cell, thereby further improving the qualified rate of photovoltaic modules. Moreover, for a back-contact solar cell, the measured angular positions can be fewer, which can reduce the measurement workload and improve the measurement efficiency of the warping.

[0084] It should be noted that, on the light-facing surface 22 of the aforementioned back-contact solar cell, at least two angular positions may be: any two angular positions, or any three angular positions, on the light-facing surface 22 of the back-contact solar cell... or all angular positions on the light-facing surface 22 of the back-contact solar cell. For example, the light-facing surface 22 of the back-contact solar cell has four angular positions, then, here it may be: measuring the positions between any two angular positions on the light-facing surface 22 of the back-contact solar cell and the first surface of the carrying platform to obtain two distances, or measuring the positions between any three angular positions and the first surface of the carrying platform to obtain three distances, or measuring the positions between four angular positions and the first surface of the carrying platform to obtain four distances.

[0085] It should be noted that the warpage of the back-contact solar cell may refer to the maximum value of at least two distances between at least two corners of the light-facing surface 22 of the back-contact solar cell and the first surface of the supporting platform. Alternatively, the warpage of the back-contact solar cell may refer to the average value of at least two distances between at least two corners of the light-facing surface 22 of the back-contact solar cell and the first surface of the supporting platform.

[0086] It should be noted that the corner of the back contact solar cell mentioned in the whole text refers to: the intersection position of two intersecting edges of the back contact solar cell, or the chamfered portion formed by the intersection position. More specifically, the corner of the back contact solar cell mentioned in the whole text refers to: the intersection position of two intersecting edges of the light-facing surface 22 of the back contact solar cell, or the chamfered portion formed by the intersection position.

[0087] For example, according to Figure 6The warpage display method shown in the figure shows that the warpage of all back-contact solar cells is less than or equal to 3 mm. The half-cells obtained by slicing each back-contact solar cell form a photovoltaic module. The length and width of each half-cell are: (181.75±0.5)×(91.3±0.5) mm. Among 500 such photovoltaic modules, the number of back-contact solar cells that are paralleled is 0.

[0088] The utility model also provides a photovoltaic module, which may include: a plurality of any of the aforementioned back-contact solar cells, in which the number of back-contact solar cells is not limited. The photovoltaic module may have the same or similar beneficial effects as any of the aforementioned back-contact solar cells and aluminum electrode pastes, and the three may be mutually referenced in their related parts. The photovoltaic module may also include: encapsulation films located on opposite sides of the back-contact solar cells, and other structures of the photovoltaic module are not specifically limited.

[0089] The utility model also provides a photovoltaic system, which may include: a plurality of the aforementioned photovoltaic modules, in which the photovoltaic modules may be arranged in an array, etc., and the number of photovoltaic modules in the photovoltaic system is not limited. The photovoltaic module may have the same or similar beneficial effects as any of the aforementioned back contact solar cells, aluminum electrode pastes, and photovoltaic modules, and the four related parts may refer to each other.

[0090] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0091] The embodiments of the utility model are described above in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the utility model, ordinary technicians in this field can also make many forms without departing from the scope of protection of the utility model and the claims, which all fall within the protection of the utility model.

Claims

1. A back contact solar cell, characterized in that: The electrode structure includes: A plurality of aluminum electrode grid lines; the aluminum electrode grid lines include an aluminum substrate and aluminum spikes, and the aluminum spikes are located on the upper part of the aluminum electrode grid lines; and an insulating glue located on the aluminum electrode grid wire and covering the aluminum thorns; Wherein, the height of the aluminum thorns is less than or equal to 6 μm.

2. The back contact solar cell according to claim 1, characterized in that: The aluminum thorns include: a first aluminum thorn and a second aluminum thorn, wherein the height of the first aluminum thorn is greater than or equal to the height of the second aluminum thorn; A difference between a height of the first aluminum thorn and a height of the second aluminum thorn is greater than or equal to 0 and less than or equal to 6 μm.

3. The back contact solar cell according to claim 1, characterized in that: The aluminum electrode grid lines are aluminum bus grid lines, and the ratio of the total height to the width of the aluminum bus grid lines is greater than or equal to 0.15 and less than or equal to 0.22; and / or, The aluminum electrode grid lines are aluminum collector grid lines, and the ratio of the total height to the width of the aluminum collector grid lines is greater than or equal to 0.27 and less than or equal to 0.

73.

4. The back-contact solar cell according to any one of claims 1 to 3, characterized in that: The aluminum electrode grid line is an aluminum bus grid line, and the ratio of the thickness of the insulating glue covering the entire aluminum bus grid line to the total height of the aluminum bus grid line is greater than or equal to 1.04 and less than or equal to 1.74; and / or, The aluminum electrode grid line is an aluminum collector grid line, and the ratio of the thickness of the insulating glue covering the entire aluminum collector grid line to the total height of the aluminum collector grid line is greater than or equal to 1.06 and less than or equal to 2.

52.

5. The back-contact solar cell according to any one of claims 1 to 3, characterized in that: The height of the aluminum spike is less than or equal to 4 μm; and / or the insulating glue is 8 μm to 17 μm higher than the aluminum spike.

6. The back contact solar cell according to claim 5, characterized in that: The insulating glue is higher than the aluminum thorn by 10 μm to 13 μm.

7. The back-contact solar cell according to any one of claims 1 to 3, characterized in that: The aluminum electrode grid line is an aluminum bus grid line, the height of the aluminum base of the aluminum bus grid line is 19 μm to 25 μm, the width of the aluminum bus grid line is 115 μm to 132 μm; the thickness of the insulating glue covering the entire aluminum bus grid line is 25 um to 42 um.

8. The back-contact solar cell according to any one of claims 1 to 3, characterized in that: The aluminum electrode grid line is an aluminum collector grid line, the height of the aluminum base of the aluminum collector grid line is 9.55μm to 16μm, the width of the aluminum collector grid line is 22μm to 35μm; the thickness of the insulating glue covering the entire aluminum collector grid line is 19μm to 33um.

9. The back-contact solar cell according to any one of claims 1 to 3, characterized in that: The back contact solar cell comprises: a substrate, the electrode structure is located on the backlight side of the substrate, the length of the substrate is 91 mm to 107 mm, and the width of the substrate is 182.2±1 mm; and / or, In the back contact solar cell, the weight of the insulating glue is 350 mg to 400 mg.

10. The back contact solar cell according to any one of claims 1 to 3, characterized in that: The back-contact solar cell is placed on a carrying platform, and when the light-facing surface at least partially contacts the carrying platform and the back-to-light surface faces away from the carrying platform, the warping degree of the back-contact solar cell is less than or equal to 3 mm.

11. A photovoltaic module, characterized in that: include: A back-contact solar cell as claimed in any one of claims 1 to 10.

12. A photovoltaic system, characterized in that: include: The photovoltaic module according to claim 11.

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