Back-contact cell and photovoltaic module

Abstract

Provided in the present application are a back-contact cell and a photovoltaic module. The cell comprises a cell sheet and at least one insulating block, wherein the cell sheet comprises a base and an electrode structure arranged on the base. The insulating block comprises: a body, which has a first surface and a second surface; and recesses, which are formed on the first surface and / or the second surface. The second surface of the insulating block is arranged facing the electrode structure and is attached to the electrode structure and the base. In the present application, by means of the formation of the recesses on the insulating block, when the insulating block is attached to the electrode structure and the base, the recesses on the second surface can form holes together with corresponding parts of the cell sheet, that is, the recesses on the second surface are not brought into contact with the cell sheet, but the parts other than the recesses are brought into contact with the cell sheet, thereby reducing the amount of an insulating material used and also greatly reducing the contact area between the insulating block and the cell sheet, thus reducing the stress between the insulating block and the cell sheet, and then preventing the problem of increased warpage of the cell sheet due to excessive stress.

Description

Back contact solar cell and photovoltaic module

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese application No. 2024110953534, filed on August 9, 2024, the contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application belongs to the technical field of photovoltaic cell manufacturing, and in particular relates to a back contact solar cell and a photovoltaic module. BACKGROUND

[0004] In a back contact solar cell (BC cell for short), the positive and negative electrodes are both on the back of the cell, and short circuit is prone to occur during interconnection. Therefore, an insulating material is needed to ensure insulation between the electrodes of different polarities in the production process of the BC cell.

[0005] Since the grid line electrodes (silver grid lines or aluminum grid lines) on the back of the cell have a certain height, generally 10-20 μm, in order to ensure that the insulating material can have a certain insulation effect, the height of the insulating material is required to be more than 20 μm than the silver grid lines or aluminum grid lines. Although the insulating material with sufficient height can protect the electrodes of different polarities, due to the large contact area between the existing insulating material and the cell, on the one hand, the cost of the insulating material is increased, and on the other hand, the stress between the insulating material and the cell (such as a silicon wafer) is large because the thermal expansion coefficients of the insulating material and the cell are different, thereby increasing the warpage of the cell and causing process risks such as broken cells and cells. SUMMARY

[0006] The present application provides a back contact solar cell and a photovoltaic module to solve the technical problem of increased warpage of the cell caused by large stress between the existing insulating material and the cell.

[0007] According to one aspect of the present application, a back contact solar cell is provided, which includes a cell and at least one insulating block. The cell includes a substrate and an electrode structure arranged on one side surface of the substrate. The insulating block includes a body having a first surface and a second surface in the thickness direction of the body, and a recess formed on the first surface and / or the second surface. The second surface of the insulating block faces the electrode structure and is attached to the electrode structure and the substrate.

[0008] In an optional scheme of the present application, the shape of the projection of the recess on the cell is a figure enclosed by a curve; preferably, the figure is a circle or an ellipse.

[0009] In an optional aspect of the present application, the pits on the first surface and / or the second surface at least satisfy one of the following conditions: a. the maximum projected area of the pits on the substrate is no more than 33% of the projected area of the insulating block on the substrate; b. the total projected area of all pits on the first surface accounts for more than 0 and no more than 5% of the first surface; c. the total projected area of all pits on the second surface accounts for more than 0 and no more than 10% of the second surface; d. the depth of the pits is no more than 50% of the maximum height of the insulating block.

[0010] In an optional aspect of the present application, the peeling strength between the second surface of the insulating block and the cell is ≥ 30 N / cm.

[0011] In an optional aspect of the present application, the second surface of each insulating block has a surface area greater than the sum of the areas of the electrode structure and the substrate covered by the second surface.

[0012] In an optional aspect of the present application, the ratio of the surface area of the second surface of each insulating block to the sum of the areas of the electrode structure and the substrate covered by the second surface is (1.1-5):1.

[0013] In an optional aspect of the present application, the first surface of the insulating block has a roughness Ra greater than 0.2 μm.

[0014] In an optional aspect of the present application, the included angle between the first surface of the insulating block and the substrate is less than 150°.

[0015] In an optional aspect of the present application, a hole is further included, which is formed inside the body.

[0016] In an optional aspect of the present application, the hole at least satisfies one of the following conditions: e. the size of the hole in the thickness direction is no more than 2 μm; f. the size of the hole in the thickness direction is no more than 8% of the thickness of the body; g. the size of the hole in the length direction of the body is no more than 10 μm; h. the size of the hole in the width direction of the body is no more than 10 μm; i. the distance between the end of the hole in the thickness direction away from the first surface and the first surface is greater than 3 μm.

[0017] In an optional aspect of the present application, the thickness of the insulating block is no less than 15 μm. And / or, the width of the insulating block is 100-500 μm. And / or, the insulating block is an insulating glue block. And / or, the pencil hardness of the insulating block is ≥ 4H. And / or, the warpage of the back-contact solar cell is less than or equal to 1.5 mm.

[0018] According to another aspect of the present application, there is provided a photovoltaic module comprising at least one back contact solar cell as described above.

[0019] In an alternative embodiment of the present application, the photovoltaic module further comprises an electrical connecting wire connected to the electrode structure of the first polarity, and the insulating block is located between the electrical connecting wire and the electrode structure of the second polarity, the first polarity being opposite to the second polarity.

[0020] In an alternative embodiment of the present application, the electrical connecting wire protrudes a convex towards the first surface of the insulating block, the convex extending into a recess of the first surface of the insulating block.

[0021] In an alternative embodiment of the present application, the photovoltaic module further comprises a busbar electrode located between the electrical connecting wire and the insulating block. The busbar electrode protrudes a convex towards the first surface of the insulating block, the convex extending into a recess of the first surface of the insulating block.

[0022] In an alternative embodiment of the present application, the peeling strength between the insulating block and the busbar electrode is 30 N / cm. And / or, the width of the busbar electrode at at least two positions in the extension direction thereof is not equal.

[0023] In an alternative embodiment of the present application, a plurality of the insulating blocks are arranged at intervals in the extension direction of the electrical connecting wire, and there is an electrode structure between two adjacent insulating blocks. And / or, a plurality of the insulating blocks are integrated in the extension direction of the electrical connecting wire. And / or, the insulating blocks on both sides of the electrical connecting wire are symmetrically arranged in the direction perpendicular to the electrical connecting wire.

[0024] In summary, the back contact solar cell and the photovoltaic module provided by the present application have at least the following beneficial effects:

[0025] In the back contact solar cell of the present application, by forming the recesses on the insulating block, when the second surface of the insulating block is attached on the electrode structure and the substrate on the back light surface of the cell piece, each recess on the second surface can form a hole (i.e. both enclose a cavity) with the corresponding part of the cell piece. That is, each recess on the second surface does not contact the cell piece, but the part (hereinafter referred to as the contact surface part) other than the recess contacts the cell piece, thereby not only reducing the amount of insulating material of the insulating block, reducing the cost, but also greatly reducing the contact area of the insulating block and the cell piece, thereby reducing the stress between the insulating block and the cell piece, and further avoiding the problem of increasing the warpage of the cell piece due to excessive stress, thereby greatly reducing the process risk of broken pieces, and piece processes. In addition, when the first surface (the surface not contacting the substrate) of the insulating block is formed with recesses, the first surface of the insulating block is not smooth and has a large roughness, and when the electrical connection line or the bus electrode is provided on the insulating block, the adhesion of the electrical connection line or the bus electrode can be increased, and the problem of easy disengagement of the electrical connection line or the bus electrode can be reduced. Moreover, when the incident light is incident on the insulating block, the insulating block with recesses and large roughness can form scattering and light trapping effects, which can avoid glare and increase the amount of light incident. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0027] FIG. 1 is a schematic view of a partial structure of a photovoltaic module of the present application;

[0028] FIG. 2 is a schematic view of an internal cross-section of an insulating block in a back contact solar cell of the present application;

[0029] FIG. 3 is a top view of an insulating block in a back contact solar cell of the present application.

[0030] The reference signs are as follows: 100, back contact solar cell; 10, insulating block; 11, body; 111, first surface; 112, second surface; 12, recess; 13, hole; 20, cell piece; 21, electrode structure; 22, substrate; 200, bus electrode; A, welding point; H, thickness direction; W, width direction; L, length direction. DETAILED DESCRIPTION

[0031] In order to make the above and other features and advantages of the present application clearer, the following further describes the present application with reference to the accompanying drawings. It should be understood that the specific examples given herein are for the purpose of explanation and are only illustrative and are not restrictive.

[0032] In addition, if features are described as being "first" or "second" for the purpose of description only, it should not be understood that relative importance or the number of the indicated technical features is implied or suggested. Features limited by "first" or "second" can explicitly or implicitly include at least one of the limited features. If "multiple" is described, it generally means at least two, such as two, three, etc., unless otherwise specifically limited.

[0033] Referring to FIG. 1, the photovoltaic module of the present application includes at least one back contact solar cell 100. Specifically, the number of back contact solar cells 100 in the photovoltaic module can be one or more. When the number of back contact solar cells 100 in the photovoltaic module is more than one, the multiple back contact solar cells 100 can be connected in series to form multiple cell strings. The multiple cell strings can be connected in series, in parallel, or in a combination of series and parallel to achieve current output. For example, the connection between two cell strings can be achieved by a busbar, and the connection between multiple back contact solar cells 100 can be achieved by welding a solder strip.

[0034] The back contact solar cell 100 includes a cell sheet 20 and at least one insulating block 10. Specifically, the cell sheet 20 includes a base 22 and an electrode structure 21 disposed on one side surface of the base 22. The side surface of the cell sheet 20 opposite to the light direction is referred to as the back light surface (usually the side surface on which the electrode structure 21 is disposed). The electrode structure 21 includes two types of electrode structures 21 with opposite polarities, which are arranged alternately and spaced apart on the back light surface. Specifically, the base 22 can be a silicon sheet with a PN junction, and one of the two types of electrode structures 21 with opposite polarities can be a positive grid line, and the other can be a negative grid line.

[0035] When the photovoltaic module is formed by the back contact solar cell 100 of the present application, adjacent back contact solar cells 100 are electrically connected and fixed by solder strips to achieve series connection between the multiple back contact solar cells 100, thereby forming the photovoltaic module.

[0036] Referring to FIG. 2, the insulation block 10 includes a body 11 and a pit 12, the body 11 has a first surface 111 and a second surface 112 in the thickness direction H of the body 11, wherein the first surface 111 is the surface of the insulation block 10 not in contact with the battery piece 20 (also referred to as the air surface), and the second surface 112 is the surface of the insulation block 10 in contact with the battery piece 20. The pit 12 can be formed only on the second surface 112, or the pit 12 is formed only on the first surface 111, or the pit 12 is formed on the first surface 111 and the second surface 112.

[0037] Wherein, the second surface 112 of the insulation block 10 is arranged on the back light surface of the battery piece 20 and adheres to the electrode structure 21 and the substrate 22, and the size, number and distribution of the pit 12 on the second surface 112 can be reasonably controlled based on the area of the battery piece 20 and the use requirement, which will be described in detail below.

[0038] It should be noted that, due to the existence of a certain height of the electrode structure 21 on the back light surface of the battery piece 20, in order to ensure that the insulation block 10 can play a certain insulation effect, the height of the insulation block 10 should be higher than the height of the electrode structure 21. Although the insulation block 10 with sufficient height can play a role in protecting the electrode structure 21, if the contact area between the insulation block 10 and the battery piece 20 is too large, it will inevitably increase the cost of the insulation material of the insulation block 10, and because the thermal expansion coefficients of the insulation block 10 and the battery piece 20 are different, it will also cause the stress between the insulation block 10 and the battery piece 20 to be large, thereby increasing the warpage of the battery piece 20, which will bring the process risk of broken pieces, and pieces, etc.

[0039] Therefore, in the back contact solar cell 100 of the embodiment of the present application, by forming the pit 12 on the insulation block 10, when the second surface 112 of the insulation block 10 adheres to the electrode structure 21 and the substrate 22 on the back light surface of the battery piece 20, each pit 12 on the second surface 112 can form a hole (i.e. the two form a cavity) with the corresponding part of the battery piece 20. That is, each pit 12 on the second surface 112 does not contact the battery piece 20, but the part (hereinafter referred to as the contact surface part) other than the pit 12 contacts the battery piece 20, thereby not only reducing the amount of insulation material of the insulation block 10 and reducing the cost, but also greatly reducing the contact area between the insulation block 10 and the battery piece 20, thereby reducing the stress between the insulation block 10 and the battery piece 20, and further avoiding the problem of increasing the warpage of the battery piece 20 due to excessive stress, thereby greatly reducing the process risk of broken pieces, and pieces, etc.

[0040] In some alternative embodiments, the insulating block 10 can be formed by curing an insulating material on the battery piece 20. Specifically, the insulating material can be an insulating glue, which is cured on the battery piece 20 to form an insulating glue block structure (i.e. the insulating block 10 of the present application), so that a better insulating effect can be achieved. Of course, the insulating block 10 can also be other solid insulating materials, such as plastic, glass, etc.

[0041] In some alternative embodiments, the thickness of the insulating block 10 is not less than 15 μm. For example, the thickness of the insulating block 10 can be 15 μm, 16 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 36 μm, 38 μm, 40 μm, 50 μm, 60 μm, etc. Here, making the thickness of the insulating block 10 reach any value within the above range can ensure that the insulating block 10 has sufficient insulating effect, thereby playing a role in protecting the opposite electrode.

[0042] In some alternative embodiments, the width of the insulating block 10 is 100-500 μm. For example, the width of the insulating block 10 can be 100 μm, 110 μm, 120 μm, 150 μm, 180 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, etc. In this way, the width of the insulating block 10 can be avoided to be too small to affect the insulating effect, or too large to increase the cost of insulating material.

[0043] In some alternative embodiments, the pencil hardness of the insulating block 10 is ≥ 4H. For example, the pencil hardness of the insulating block 10 can be 4H, 5H, 6H, 7H, 8H, 9H, 10H, etc. When the pencil hardness of the insulating block 10 is greater than or equal to 4H, the insulating block 10 has sufficient hardness, so that the insulating block 10 is not prone to crack or breakage when the back contact solar cell 100 is used, thereby ensuring the safety of the back contact solar cell 100 when used.

[0044] In some embodiments, the warpage of the back contact solar cell 100 is less than or equal to 1.5 mm. For example, the warpage of the back contact solar cell 100 can be 1.5 mm, 1.4 mm, 1.3 mm, 1.2 mm, 1.1 mm, 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, 0.1 mm, etc. When the warpage of the back contact solar cell 100 is within the above values, the process risks such as breakage and piece-to-piece of the process are avoided.

[0045] Referring to FIG. 2, the shape of the projection of the pit 12 on the cell sheet 20 is a figure enclosed by a curve. The "figure enclosed by a curve" as used herein means that the shape of the projection of the pit 12 on the cell sheet 20 has no sharp corners and sharp points, but is a figure enclosed by a smooth curve, so that there is no problem of stress concentration between the part of the contact surface of the second surface 112 (i.e. the part of the second surface 112 described above except the pit 12) near the pit 12 and the cell sheet 20. Preferably, the figure is a circle or an ellipse.

[0046] In order to reduce the amount of insulating material of the insulating block 10 as much as possible while ensuring the insulating effect of the insulating block 10, the parameters of the pits 12 on the first surface 111 and / or the second surface 112 can be controlled and optimized.

[0047] In some optional embodiments, the pits 12 on the first surface 111 and / or the pits 12 on the second surface 112 at least meet one of the following a-d conditions.

[0048] a. The maximum projection area of the pit 12 on the base 22 is not more than 33% of the projection area of the insulating block 10 on the base 22. The maximum projection area is also equal to the area enclosed by the edge profile of the pit 12 on the surface of the base 22. In this way, the proportion of the pit 12 can be avoided to be too large to affect the insulating effect.

[0049] b. The total projection area of all pits 12 on the first surface 111 on the first surface 111 is greater than 0 and not more than 5%. For example, the total projection area of all pits 12 on the first surface 111 on the first surface 111 can be 1%, 1.2%, 1.5%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any value between 0 and 5%. In this way, the proportion of the pit on the first surface 111 can be avoided to be too large to pierce the insulating block 10 by the sharp structure of the electrode structure 21.

[0050] c. The total projection area of all pits 12 on the second surface 112 on the second surface 112 is greater than 0 and not more than 10%. For example, the total projection area of all pits 12 on the second surface 112 on the second surface 112 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any value between 0 and 10%. Preferably, the total projection area of all pits 12 on the second surface 112 on the second surface 112 is greater than the total projection area of all pits 12 on the first surface 111 on the first surface 111. In this way, the proportion of the pit 12 on the second surface 112 can be avoided to be too large to affect the adhesion strength of the insulating block 10 on the base 22.

[0051] d.The depth of the recess 12 is not more than 50% of the maximum height of the insulating block 10. Here, the depth of the recess 12 refers to the dimension of the recess 12 in the thickness direction H of the body 11. With such a design, the insulating block 10 can have a better insulation effect.

[0052] In some alternative embodiments, during the use of the back contact solar cell 100, in order to ensure that the insulating block 10 is not easily peeled off from the cell 20, the connection strength between the second surface 112 of the insulating block 10 and the cell 20 is equal to or greater than 30 N / cm, thereby ensuring that the peeling strength between the second surface 112 of the insulating block 10 and the cell 20 is equal to or greater than 30 N / cm.

[0053] It can be understood that the "peeling strength" refers to the force required to separate the insulating block 10 from the cell 20. Specifically, by controlling the area of the recess 12 on the second surface 112 and the area of the contact surface part (part other than the recess 12) in contact with the cell 20, the connection strength between the contact surface part of the second surface 112 and the cell 20 can be equal to or greater than 30 N / cm, so that the peeling strength between the second surface 112 of the insulating block 10 and the cell 20 is equal to or greater than 30 N / cm.

[0054] In some alternative embodiments, the surface area of the second surface 112 of each insulating block 10 is greater than the sum of the areas of the electrode structure 21 and the base 22 covered by the second surface 112. Here, the surface area of the second surface 112 includes the surface area of all recesses 12 on the second surface 112 and the surface area of the part other than the recess 12. In this embodiment, based on the recess 12 provided on the second surface 112, the contact area between the second surface 112 of the insulating block 10 and the cell 20 is reduced, thereby reducing the stress between the insulating block 10 and the cell 20, and thus the cell 20 warping problem can be effectively improved.

[0055] It should be noted that, if the ratio of the surface area of the second surface 112 of each insulating block 10 to the sum of the areas of the electrode structure 21 and the substrate 22 covered by the second surface 112 is larger, the total surface area of all the pits 12 on the second surface 112 is larger, the surface area of the part of the second surface 112 other than the pits 12 is smaller, the stress between the insulating block 10 and the battery sheet 20 is smaller, and the connecting strength between the insulating block 10 and the battery sheet 20 is also smaller; conversely, if the ratio of the surface area of the second surface 112 of each insulating block 10 to the sum of the areas of the electrode structure 21 and the substrate 22 covered by the second surface 112 is smaller, the total surface area of all the pits 12 on the second surface 112 is smaller, the surface area of the part of the second surface 112 other than the pits 12 is larger, the stress between the insulating block 10 and the battery sheet 20 is larger, and the connecting strength between the insulating block 10 and the battery sheet 20 is also larger.

[0056] Therefore, in order to guarantee the connecting strength between the insulating block 10 and the battery sheet 20 while reducing the stress between the insulating block 10 and the battery sheet 20 as much as possible, preferably, the ratio of the surface area of the second surface 112 of each insulating block 10 to the sum of the areas of the electrode structure 21 and the substrate 22 covered by the second surface 112 is (1.1-5):1. For example, the ratio of the surface area of the second surface 112 of each insulating block 10 to the sum of the areas of the electrode structure 21 and the substrate 22 covered by the second surface 112 can be 1.1:1, 1.2:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 5:1, or any value between 1.1 and 5.

[0057] Due to the existence of the pits 12, the roughness of the surface of the insulating block 10 is also large. Through process control or material control or both, the roughness Ra of the first surface 111 of the insulating block 10 can be greater than 0.2 μm. Similarly, the roughness Ra of the second surface 112 of the insulating block 10 can also be controlled through process control or material control or both to meet certain requirements.

[0058] In some optional embodiments, the included angle between the first surface 111 of the insulating block 10 and the substrate 22 is less than 150°. Here, the included angle is the included angle of the inner side of the insulating block 10, and at this time, the contact edge tension of the insulating block 10 and the substrate 22 is smaller, and the adhesion performance is better. For example, the included angle between the first surface 111 of the insulating block 10 and the substrate 22 is 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, etc.

[0059] Referring to FIG. 3, the insulation block 10 further comprises a hole 13 formed inside the body 11. Among them, the holes 13 inside the insulation block 10 are required to be distributed so that two holes 13 cannot coincide, or two holes 13 coincide as one large hole, and are counted as one hole 13.

[0060] Specifically, the hole 13 can accommodate a certain volume of gas (such as air) inside, so that based on the hole 13 and the air inside, the insulation block 10 can have a light trapping effect during use of the photovoltaic module, thereby improving the light absorption rate of the photovoltaic module, and further improving the working efficiency of the photovoltaic module.

[0061] In order to reduce the amount of insulation material used in the insulation block 10 as much as possible while ensuring the light trapping effect of the insulation block 10, the holes 13 inside the insulation block 10 can be controlled and optimized.

[0062] In some optional embodiments, the holes 13 inside the insulation block 10 at least meet one of the following e-i conditions: e. The size of the hole 13 in the thickness direction H of the body 11 is not more than 2 μm, for example, it can be specifically 0.5 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, etc.; f. The size of the hole 13 in the thickness direction H of the body 11 is not more than 8% of the thickness of the body 11; g. The size of the hole 13 in the length direction L of the body 11 is not more than 10 μm, for example, it can be specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.; h. The size of the hole 13 in the width direction W of the body 11 is not more than 10 μm, for example, it can be specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.; i. The distance between the end of the hole 13 in the thickness direction H of the body 11 away from the first surface 111 and the first surface 111 is greater than 3 μm. At this time, the hole is relatively small, and the adverse effect on the insulation performance of the insulation block is small, and the purposes of light trapping and material saving can be achieved.

[0063] In an optional embodiment, the photovoltaic module of the present application further comprises an electrical connection wire (not shown) connected to the electrode structure 21 of the first polarity. For example, in a cell string (containing a plurality of cell pieces), the electrical connection wire is welded to the electrode structure 21 of the first polarity of the first cell piece and the electrode structure 21 of the second polarity of the second cell piece, and so on. Among them, the polarity of the first polarity is opposite to the polarity of the second polarity. Specifically, the electrode structure 21 of the first polarity can be a positive electrode structure, and correspondingly the electrode structure 21 of the second polarity can be a negative electrode structure, and vice versa.

[0064] The electric connecting wire can be, but is not limited to, a tinned copper strip, a tin-coated copper strip, a tinned aluminum strip, a tin-coated aluminum strip, etc.

[0065] In this embodiment, the insulating block 10 is located between the electric connecting wire and the electrode structure 21 of the second polarity, i.e. when the electric connecting wire is connected with the positive electrode structure, the position of the negative electrode structure crossed by the electric connecting wire is provided with the insulating block 10. The first surface 111 of the insulating block 10 is arranged to face the electric connecting wire and is attached to the electric connecting wire. When the first surface 111 of the insulating block 10 is attached to the electric connecting wire, if the first surface 111 of the insulating block 10 is also formed with the recess 12, part of the electric connecting wire can extend into the recess 12 on the first surface 111, so that the pulling force and the attachment force between the insulating block 10 and the electric connecting wire are larger, thereby improving the reliability of the electric connecting wire and avoiding the electric connecting wire from falling off. Therefore, preferably, in this embodiment, the first surface 111 of the insulating block 10 is also formed with the recess 12.

[0066] In other words, at the position where the electric connecting wire contacts the insulating block 10, the first surface 111 of the insulating block 10 can be protrudingly formed with a protrusion, and the protrusion extends into the recess 12 of the first surface 111 of the insulating block 10. Based on the existence of the protrusion, the surface of the electric connecting wire contacting the insulating block 10 is uneven, and the position and shape of each protrusion can match the corresponding recess 12.

[0067] In order to realize the connection between the electric connecting wire and the electrode structure 21, a soldering point (not shown) can be arranged on the electrode structure 21, and the electric connecting wire is connected with the plurality of electrode structures 21 through the soldering points on the plurality of electrode structures 21, so as to realize the connection between the back contact solar cell 100 and other back contact solar cells 100.

[0068] In another optional embodiment, with reference to FIG. 1, the photovoltaic module of the present application further comprises a bus electrode 200, and the bus electrode 200 is located between the electric connecting wire and the insulating block 10.

[0069] In this embodiment, the first surface 111 of the insulating block 10 is arranged to face the bus electrode 200 and is attached to the bus electrode 200. When the first surface 111 of the insulating block 10 is attached to the bus electrode 200, if the first surface 111 of the insulating block 10 is also formed with the recess 12, part of the bus electrode 200 can extend into the recess 12 on the first surface 111, so that the pulling force and the attachment force between the insulating block 10 and the bus electrode 200 are larger, thereby improving the reliability of the bus electrode 200 and avoiding the bus electrode 200 from falling off. Therefore, preferably, in this embodiment, the first surface 111 of the insulating block 10 is also formed with the recess 12.

[0070] In other words, at the position where the busbar 200 contacts the insulating block 10, the first surface 111 of the busbar 200 facing the insulating block 10 can be protruded with protrusions extending into the recesses 12 of the first surface 111 of the insulating block 10. Based on the presence of the protrusions, the surface of the busbar 200 contacting the insulating block 10 is uneven, and the position and shape of each protrusion can match the corresponding recess 12.

[0071] It can be understood that the busbar 200 can be multiple in number, and each busbar 200 is used to connect with multiple electrode structures 21 of the same polarity to collect the current collected by the multiple electrode structures 21 of the same polarity. Specifically, the multiple busbars 200 include busbars 200 of positive polarity and busbars 200 of negative polarity, the busbars 200 of positive polarity are connected with multiple electrode structures 21 of positive polarity to collect the current collected by the multiple electrode structures 21 of positive polarity, and the busbars 200 of negative polarity are used to connect with multiple electrode structures 21 of negative polarity to collect the current collected by the multiple electrode structures 21 of negative polarity.

[0072] In this embodiment, the electric connection line is connected with the busbar 200. For example, in one battery string, the electric connection line is connected with the busbar 200 of positive polarity of the first battery piece, and the electric connection line is connected with the busbar 200 of negative polarity of the second battery piece.

[0073] In order to realize the connection between the electric connection line and the busbar 200, the soldering points A can be provided on the busbar 200, and the electric connection line is connected with multiple busbars 200 of the same polarity through the soldering points A on the multiple busbars 200 to realize the connection between the back contact solar cell 100 and other back contact solar cells 100.

[0074] In the use of the photovoltaic module, in order to ensure that the busbar 200 is not easy to be peeled off from the insulating block 10, the connection strength between the first surface 111 of the insulating block 10 and the busbar 200 is equal to or greater than 30 N / cm, thereby ensuring that the peeling strength between the insulating block 10 and the busbar 200 is equal to or greater than 30 N / cm, and thereby the reliability of the busbar can be ensured.

[0075] In an optional embodiment, referring to FIG. 1, the width of the busbar 200 at at least two positions in the extension direction thereof is not equal. Preferably, the width of the busbar 200 in the extension direction thereof is alternately increased and decreased, and the widest part of the width of the busbar 200 in the extension direction thereof is provided with the soldering point A.

[0076] In an optional embodiment, referring to FIG. 1, the plurality of insulating blocks 10 are arranged at intervals in the extension direction of the electric connection line, and the electrode structure 21 is provided between any two adjacent insulating blocks 10. Here, each insulating block 10 can realize electrical isolation between the electric connection line and the corresponding one of the heterogeneous electrodes. Alternatively, the plurality of insulating blocks 10 can be integrated, i.e., the plurality of insulating blocks 10 are arranged continuously without interruption, and only the part where the electric connection line and the electrode structure or the bus electrode connecting part are absent.

[0077] In an optional embodiment, referring to FIG. 1, the insulating blocks 10 on both sides of the electric connection line are arranged symmetrically in the direction perpendicular to the electric connection line, so that the heterogeneous electrodes on both sides of the electric connection line can be electrically isolated.

[0078] The application also discloses a preparation method of the back contact solar cell. The insulating block is formed by curing the insulating glue. The preparation method comprises the following steps: mixing the purchased insulating glue preform (the two-component glue can be mixed or not mixed) with a foaming agent and heating to obtain the insulating glue, and then coating the insulating glue on the cell sheet and curing to form the insulating block.

[0079] In the process of mixing the purchased insulating glue preform (the two-component glue can be mixed or not mixed) with a foaming agent and heating to obtain the insulating glue, the insulating glue contains micro-bubbles. The size of the bubbles can be controlled by controlling the air pressure, stirring and heating time. The number of the final bubbles can be controlled by controlling the amount of the foaming agent added. The preparation method of the insulating glue is a prior art, and the application will not be described in detail.

[0080] In some embodiments, the purchased insulating glue preform is stirred, and a gas is introduced during the stirring. The gas is a non-flammable or non-combustible gas in air.

[0081] In some embodiments, the insulating glue preform can also be co-extruded with a compressed gas.

[0082] In some embodiments, the insulating glue is coated on the cell sheet and cured to form the insulating block. The insulating glue is cured by drying or ultraviolet irradiation. The hardness, pits or bubbles of the cured insulating block can be controlled by adjusting the drying temperature curve, adjusting the drying time or adjusting the ultraviolet irradiation time.

[0083] Although the embodiments of the application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the application.

Claims

1. A back-contact solar cell (100), wherein, Includes a battery cell (20) and at least one insulating block (10); The battery cell (20) includes a substrate (22) and an electrode structure (21) disposed on one side surface of the substrate (22); The insulating block (10) includes: a body (11) having a first surface (111) and a second surface (112) in its thickness direction (H); And pits (12) formed on the first surface (111) and / or the second surface (112); The second surface (112) of the insulating block (10) is disposed facing the electrode structure (21) and attached to the electrode structure (21) and the substrate (22).

2. The back-contact solar cell (100) according to claim 1, wherein, The orthographic projection of the pit (12) onto the battery cell (20) is a shape formed by curves; preferably, the shape is circular or elliptical.

3. The back-contact solar cell (100) according to claim 1, wherein, The pits (12) on the first surface (111) and / or the second surface (112) satisfy at least one of the following conditions: a. The maximum projected area of ​​the pit (12) on the substrate (22) does not exceed 33% of the projected area of ​​the insulating block (10) on the substrate (22); b. The total projected area of ​​all pits (12) on the first surface (111) is greater than 0 and not greater than 5%; c. The total projected area of ​​all pits (12) on the second surface (112) is greater than 0 and not greater than 10%; d. The depth of the pit (12) does not exceed 50% of the maximum height of the insulating block (10).

4. The back-contact solar cell (100) according to claim 1, wherein, The peel strength between the second surface (112) of the insulating block (10) and the battery cell (20) is ≥30 N / cm.

5. The back-contact solar cell (100) according to claim 1, wherein, The surface area of ​​the second surface (112) of each insulating block (10) is greater than the sum of the areas of the electrode structure (21) and the substrate (22) covered by the second surface (1).

6. The back-contact solar cell (100) according to claim 5, wherein, The ratio of the surface area of ​​the second surface (112) of each insulating block (10) to the sum of the areas of the electrode structure (21) and the substrate (22) covered by the second surface (1) is (1.1 to 5):

1.

7. The back-contact solar cell (100) according to claim 1, wherein, The roughness Ra of the first surface (111) of the insulating block (10) is greater than 0.2 μm.

8. The back-contact solar cell (100) according to claim 1, wherein, The angle between the first surface (111) of the insulating block (10) and the substrate (22) is less than 150°.

9. The back-contact solar cell (100) according to claim 1, wherein, It also includes holes (13) formed inside the body (11).

10. The back-contact solar cell (100) according to claim 9, wherein, The hole (13) must satisfy at least one of the following conditions: e. The size of the hole (13) in the thickness direction (H) does not exceed 2 μm; f. The size of the hole (13) in the thickness direction (H) does not exceed 8% of the thickness of the body (11); g. The size of the hole (13) in the length direction (L) of the body (11) does not exceed 10 μm; h. The size of the hole (13) in the width direction (W) of the body (11) does not exceed 10 μm; i. The distance between the end of the hole (13) facing away from the first surface (111) in the thickness direction (H) and the first surface (111) is greater than 3 μm.

11. The back-contact solar cell (100) according to claim 1, wherein, The thickness of the insulating block (10) is not less than 15 μm; and / or The width of the insulating block (10) is 100-500 μm; and / or The insulating block (10) is an insulating rubber block; and / or The pencil hardness of the insulating block (10) is ≥4H; and / or The warpage of the back-contact solar cell is less than or equal to 1.5 mm.

12. A photovoltaic module, wherein, It includes at least one back-contact solar cell (100) as described in any one of claims 1-11.

13. The photovoltaic module according to claim 12, wherein, It also includes an electrical connection wire, which is connected to the electrode structure (21) of the first polarity; The insulating block (10) is located between the electrical connection line and the electrode structure (21) of the second polarity, the first polarity being opposite to the second polarity.

14. The photovoltaic module according to claim 13, wherein, The electrical connection wire protrudes from the first surface (111) of the insulating block (10) and has a protrusion that extends into a recess (12) of the first surface (111) of the insulating block (10).

15. The photovoltaic module according to claim 13, wherein, It also includes a bus electrode (200) located between the electrical connection line and the insulating block (10); The bus electrode (200) has a protrusion on the first surface (111) facing the insulating block (10), and the protrusion extends into the pit (12) of the first surface (111) of the insulating block (10).

16. The photovoltaic module according to claim 15, wherein, The peel strength between the insulating block (10) and the bus electrode (200) is 30 N / cm; and / or The width of the bus electrode (200) is not equal at at least two locations in its extension direction.

17. The photovoltaic module according to claim 13, wherein, In the extending direction of the electrical connection line, a plurality of insulating blocks are spaced apart (10), and an electrode structure (21) is provided between two adjacent insulating blocks (10); and / or In the extending direction of the electrical connection line, a plurality of the insulating blocks (10) are connected as one unit; and / or The insulating blocks (10) on both sides of the electrical connection line are arranged symmetrically in a direction perpendicular to the electrical connection line.

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