Back contact photovoltaic module

Abstract

The invention relates to the technical field of photovoltaic, in particular to a back contact photovoltaic module which comprises battery strings and bus bars, each battery string comprises battery pieces and welding strips, the welding strips are connected with the adjacent battery pieces, and the bus bars are connected with the adjacent battery strings; first grid lines with different polarities are arranged on the back surfaces of the battery pieces, the bus bars are arranged on the back surfaces of the battery pieces, the first grid lines extend in the first direction, and the bus bars extend in the second direction; an insulating film is arranged between the bus bar and the first grid line of one polarity, and a conductive film is arranged between the bus bar and the first grid line of the other polarity. In the invention, the bus bar is directly connected with the positive electrode first grid line or the negative electrode first grid line, so that a welding strip does not need to be arranged between the bus bar and the positive electrode first grid line or the negative electrode first grid line, the length of the welding strip can be shortened, the use amount of the welding strip is reduced, and the production cost is reduced. And the bus bar is directly arranged on the back surface of the battery piece, so that the area ratio of the battery piece in the back contact photovoltaic module can be improved, and the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and particularly to a back-contact photovoltaic module. Background Art

[0002] Photovoltaic modules can directly convert solar radiant energy into electrical energy, mainly based on the photovoltaic effect of crystalline silicon. That is, when the photons of sunlight are absorbed by the semiconductor crystalline silicon, electron-hole pairs are generated. When these electron-hole pairs reach the p-n junction composed of p-type crystalline silicon and n-type crystalline silicon, they are separated to both sides of the p-n junction by the junction electric field. When an external load is connected, a photocurrent is formed and electrical energy is output.

[0003] In a photovoltaic module, welding tapes connect adjacent solar cells to form a series-connected solar cell string. At the head and tail of the solar cell string, the welding tapes are connected to the bus bars to connect multiple solar cell strings in parallel. Since the amount of welding tapes used is large, the production cost of the photovoltaic module is relatively high. Summary of the Invention

[0004] This application provides a back-contact photovoltaic module, which reduces the amount of welding tapes used in the back-contact photovoltaic module by directly connecting the bus bar to the first grid line, thereby reducing the production cost of the back-contact photovoltaic module.

[0005] A back-contact photovoltaic module provided by an embodiment of this application includes a solar cell string and a bus bar. The solar cell string includes solar cells and welding tapes. The welding tapes connect adjacent solar cells, and the bus bar connects adjacent solar cell strings; On the back surface of the solar cell, first grid lines with different polarities are provided. The bus bar is arranged on the back surface of the solar cell. The first grid lines extend along a first direction, and the bus bar extends along a second direction. The second direction intersects with the first direction; An insulating film is provided between the bus bar and the first grid lines of one polarity, and a conductive film is provided between the bus bar and the first grid lines of the other polarity. The welding tapes have no direct contact with the bus bar.

[0006] In a possible design, along the first direction, the width d2 of the insulating film is greater than the width d1 of the bus bar; and / or, along the first direction, the width d3 of the conductive film is greater than the width d1 of the bus bar.

[0007] In a possible design, the ratio of the width d2 of the insulating film to the width d1 of the bus bar satisfies: 1 < d2 / d1 ≤ 2.

[0008] In a possible design, an avoidance portion is provided on the insulating film that penetrates the insulating film along the thickness direction of the solar cell, and the conductive film is arranged in the avoidance portion.

[0009] In a possible design, the avoidance portion passes through one side of the insulating film along the first direction, and a width d2 of the insulating film is equal to or greater than a dimension of the avoidance portion along the first direction (X).

[0010] In a possible design, along the second direction, a plurality of the insulating films are provided, a plurality of the conductive films are provided, and the insulating films and the conductive films are arranged alternately.

[0011] In a possible design, the width d2 of the insulating film is equal to the width d3 of the conductive film.

[0012] In a possible design, along the second direction, the length L of the conductive film satisfies: 0.2 mm ≤ L ≤ 1.5 mm.

[0013] In a possible design, a side of the welding ribbon close to the bus bar partially overlaps with the conductive film.

[0014] In a possible design, along the second direction, the conductive film partially extends to a side of the insulating film facing away from the battery cell.

[0015] In the present application, when a conductive film is provided between the bus bar and the first positive grid line, and an insulating film is provided between the bus bar and the first negative grid line, the bus bar can be directly connected to the first positive grid line, so that there is no need to provide a welding strip between the bus bar and the first positive grid line, thereby shortening the length of the welding strip, reducing the amount of welding strip used, and reducing the cost of the back-contact photovoltaic module. Similarly, when a conductive film is provided between the bus bar and the first negative grid line, and an insulating film is provided between the bus bar and the first positive grid line, the bus bar can be directly connected to the first negative grid line, so that there is no need to provide a welding strip between the bus bar and the first negative grid line, thereby shortening the length of the welding strip, reducing the amount of welding strip used, and reducing the cost of the back-contact photovoltaic module.

[0016] At the same time, the busbar is directly set on the back of the cell, which can increase the area ratio of the cell in the back-contact photovoltaic module, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic module. Compared with the current method of first connecting the cell and the busbar on the side of the cell through a welding ribbon, and then folding the busbar from the side of the cell to the back of the cell, on the one hand, it simplifies the production steps of the back-contact photovoltaic module, and on the other hand, there is no bending welding ribbon between the cell and the busbar, which is not easy to cause the busbar to be disconnected from the cell due to the welding ribbon breaking, so the reliability of the back-contact photovoltaic module is higher.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of a back-contact photovoltaic module in the prior art; Figure 2 It is a partial structural diagram of the back-contact photovoltaic module provided by the present application in a specific embodiment; Figure 3 It is a partial structural diagram of the back-contact photovoltaic module provided by the present application in another specific embodiment; Figure 4 It is a partial structural diagram of the back-contact photovoltaic module provided by the present application in yet another specific embodiment; Figure 5 It is Figure 4 a schematic structural diagram of the insulating film in Figure 6 It is a schematic structural diagram of the back-contact photovoltaic module provided by the present application.

[0019] Reference numerals: 1 - Battery string; 11 - Battery cell; 111 - First grid line; 112 - Second grid line; 12 - Solder ribbon; 2 - Bus bar; 3 - Insulating film; 4 - Conductive film; 5 - Front encapsulation structure; 6 - Front film layer; 7 - Back film layer; 8 - Back encapsulation structure.

[0020] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. Detailed Description of the Embodiments

[0021] For a better understanding of the technical solutions of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0022] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0023] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0024] It should be understood that the term "and / or" used herein is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in this text, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0025] It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described from the angle shown in the drawings and should not be construed as a limitation on the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that an element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0026] As Figure 1 shown, currently, a back-contact photovoltaic module includes a plurality of cell strings 1, and the bus bar 2 is connected to the head or tail of the cell string 1 through the solder tape 12, which makes the solder tape 12 need to extend to the outside of the cell 11, and thus the usage amount of the solder tape 12 is relatively large.

[0027] The present application provides a back-contact photovoltaic module. The back-contact photovoltaic module includes a cell string 1 and a bus bar 2. The cell string 1 includes cells 11 and solder tapes 12. The solder tapes 12 connect adjacent cells 11, and the bus bar 2 connects adjacent cell strings 1.

[0028] The solder tapes 12 connect adjacent cells 11 to form a cell string 1 in series; the bus bar 2 connects adjacent cell strings 1 to form a cell string group in parallel and makes the cell string groups connected in series. For example, the back-contact photovoltaic module may include three series-connected cell string groups, and each cell string group includes four parallel-connected cell strings 1. It can be understood that the back-contact photovoltaic module can also be strung through other connection methods. For the convenience of description, the direction in which the solder tape 12 extends is defined as the first direction X, and the direction in which the bus bar 2 extends is defined as the second direction Y, and the first direction X intersects with the second direction Y.

[0029] The cell 11 is a back-contact cell. The back-contact cell has a front side and a back side. The front side is the light-receiving surface of the back-contact cell, and the back side is the light-blocking surface of the back-contact cell. From the front side to the back side of the back-contact cell, the back-contact cell sequentially includes: a front surface passivation and antireflection layer, a silicon substrate, a back surface tunneling layer, alternately arranged N-type doped regions and P-type doped regions, a back surface passivation layer and cell electrodes. The N-type doped regions and P-type doped regions are alternately arranged on the lower surface of the back surface tunneling layer. The cell electrodes include a first grid line 111 and a second grid line 112 with different polarities. The first grid line 111 extends along a first direction X, and the second grid line 112 extends along a second direction Y. One polarity of the second grid line 112 is connected to the P-type doped region (defined as the positive second grid line 112) to collect the current generated by the P-type doped region, and the other polarity of the second grid line 112 is connected to the N-type doped region (defined as the negative second grid line 112) to collect the current generated by the N-type doped region. One polarity of the first grid line 111 is connected to at least part of the positive second grid line 112 (defined as the positive first grid line 111) to collect the current collected by the positive second grid line 112, so that the current collected by the positive second grid line 112 can be directly or indirectly led out through the solder strip 12. The other polarity of the first grid line 111 is connected to at least part of the negative second grid line 112 (defined as the negative first grid line 111) to collect the current collected by the negative second grid line 112, so that the current collected by the negative second grid line 112 can be directly or indirectly led out through the solder strip 12.

[0030] The bus bar 2 is arranged on the back side of the cell 11. An insulating film 3 is arranged between the bus bar 2 and one polarity of the first grid line 111, and a conductive film 4 is arranged between the bus bar 2 and the other polarity of the first grid line 111. The green lines in the figure show the insulating film 3, and the orange lines show the conductive film 4.

[0031] When a conductive film 4 is arranged between the bus bar 2 and the positive first grid line 111 and an insulating film 3 is arranged between the bus bar 2 and the negative first grid line 111, the bus bar 2 can be directly connected to the positive first grid line 111, so that there is no need to arrange a solder strip 12 between the bus bar 2 and the positive first grid line 111, that is, the solder strip 12 has no direct contact with the bus bar 2, thereby shortening the length of the solder strip 12, reducing the usage amount of the solder strip 12, and reducing the cost of the back-contact photovoltaic module.

[0032] Similarly, when a conductive film 4 is arranged between the bus bar 2 and the negative first grid line 111 and an insulating film 3 is arranged between the bus bar 2 and the positive first grid line 111, the bus bar 2 can be directly connected to the negative first grid line 111, so that there is no need to arrange a solder strip 12 between the bus bar 2 and the negative first grid line 111, thereby shortening the length of the solder strip 12, reducing the usage amount of the solder strip 12, and reducing the cost of the back-contact photovoltaic module.

[0033] Meanwhile, the bus bar 2 is directly disposed on the back surface of the battery cell 11, which can increase the area ratio of the battery cell 11 in the back-contact photovoltaic module, thereby improving the photoelectric conversion efficiency of the back-contact photovoltaic module. Compared with the current method of first connecting the battery cell 11 and the bus bar 2 located on the side of the battery cell 11 through the welding strip 12 and then folding the bus bar 2 from the side of the battery cell 11 to the back surface of the battery cell 11, on the one hand, the production steps of the back-contact photovoltaic module are simplified, and on the other hand, there is no bent welding strip 12 between the battery cell 11 and the bus bar 2, so it is not easy to have the problem that the welding strip 12 breaks and the bus bar 2 is disconnected from the battery cell 11. Therefore, the reliability of the back-contact photovoltaic module is higher.

[0034] Specifically, as Figure 2 shown, along the first direction X, the width d2 of the insulating film 3 is greater than the width d1 of the bus bar 2, so as to prevent the bus bar 2 connected to the positive first grid line 111 from extending outside the insulating film 3 and contacting the negative first grid line 111 to generate a short circuit, and prevent the bus bar 2 connected to the negative first grid line 111 from extending outside the insulating film 3 and contacting the positive first grid line 111 to generate a short circuit.

[0035] Along the first direction X, the width d3 of the conductive film 4 is greater than the width d1 of the bus bar 2, so that the contact area between the bus bar 2 and the conductive film 4 is large, and the contact area between the conductive film 4 and the first grid line 111 is large, so that the resistance at the connection between the bus bar 2 and the first grid line 111 is small, thereby reducing the loss of electric energy during transmission.

[0036] More specifically, the ratio of the width d2 of the insulating film 3 to the width d1 of the bus bar 2 satisfies: 1 < d2 / d1 ≤ 2. For example, the ratio of the width d2 to the width d1 can specifically be: 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, etc.

[0037] The ratio of the width d2 of the insulating film 3 to the width d1 of the bus bar 2 should not be too large or too small. If the ratio of the width d2 to the width d1 is too large (for example, d2 / d1 is greater than 2), the width of the insulating film 3 is too large, and the production cost of the back-contact photovoltaic module is relatively high; if the ratio of the width d2 to the width d1 is too small (for example, d2 / d1 is equal to or less than 1), the insulating film 3 cannot effectively isolate the bus bar 2 and the battery cell 11, and the bus bar 2 is easy to contact the battery cell 11 to cause a short circuit. Therefore, the ratio of the width d2 of the insulating film 3 to the width d1 of the bus bar 2 should be set within a reasonable range to prevent the bus bar 2 from contacting the battery cell 11 to cause a short circuit while keeping the cost of the back-contact photovoltaic module relatively low.

[0038] The ratio of the width d3 of the conductive film 4 to the width d1 of the bus bar 2 satisfies: 1 < d3 / d1 ≤ 2. For example, the ratio of the width d3 to the width d1 can specifically be: 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, etc.

[0039] The ratio of the width d3 of the conductive film 4 to the width d1 of the bus bar 2 should not be too large or too small. If the ratio of the width d3 to the width d1 is too large (for example, d3 / d1 is greater than 2), the width of the conductive film 4 is too large, and the production cost of the back-contact photovoltaic module is relatively high; if the ratio of the width d3 to the width d1 is too small (for example, d3 / d1 is less than 1), on the one hand, when the bus bar 2 slightly deviates from the preset position, the conductive film 4 is prone to disconnect from the bus bar 2, and on the other hand, the contact area between the bus bar 2, the first grid line 111 and the conductive film 4 is relatively small, the resistance is relatively large when the current flows through, and the loss of electric energy during transmission increases. Therefore, the ratio of the width d3 of the conductive film 4 to the width d1 of the bus bar 2 should be set within a reasonable range to prevent the conductive film 4 from being easily disconnected from the bus bar 2 while keeping the cost of the back-contact photovoltaic module low.

[0040] In one embodiment, as Figure 2 shown, the first grid line 111 is the main grid, the second grid line 112 is the fine grid, the positive first grid line 111 is connected to all the positive second grid lines 112 to collect the current collected by the positive second grid lines 112, the negative first grid line 111 is connected to all the negative second grid lines to collect the current collected by the negative second grid lines 112, and the welding tape 12 covers the first grid line 111, thereby leading out the current collected by the first grid line 111.

[0041] At the head and tail of the battery string 1 along the first direction X, the bus bar 2 connected to the positive first grid line 111 is also connected to some of the positive second grid lines 112. The welding tape 12 covering the positive first grid line 111 can abut against or partially overlap with the conductive film 4, so that the current collected by the positive second grid lines 112 can partially flow directly to the bus bar 2, partially flow to the bus bar 2 through the positive first grid line 111, and partially flow to the bus bar 2 through the welding tape 12 connected to the positive first grid line 111, thereby improving the current collection effect of the bus bar 2 on the current. The welding tape 12 covering the positive first grid line 111 can also not contact the conductive film 4, so that the length of the welding tape 12 can be shorter to reduce the cost of the back-contact photovoltaic module.

[0042] Similarly, the bus bar 2 connected to the negative first grid line 111 is also connected to some of the negative second grid lines 112. The welding tape 12 covering the negative first grid line 111 can abut against, partially overlap with or not contact the conductive film 4.

[0043] Specifically, a plurality of insulating films 3 are provided, and a plurality of conductive films 4 are provided. The insulating films 3 and the conductive films 4 are arranged alternately, so that the insulating films 3 and the conductive films 4 can respectively correspond to the alternately arranged positive first grid lines 111 and negative first grid lines 111.

[0044] In another embodiment, as Figure 3 shown, the first grid line 111 is an edge main grid, and the second grid line 112 is a fine grid. The edge main grid is only connected to part of the positive second grid lines 112 or part of the negative second grid lines 112. Compared with setting an entire main grid, the paste usage of the first grid line 111 is reduced, which is beneficial to reducing the production cost of the back-contact photovoltaic module.

[0045] The solder ribbon 12 is connected to the positive first grid line 111 and also to the positive second grid lines 112 that are not connected to the positive first grid line 111. Therefore, the solder ribbon 12 can collect the current collected by all the positive second grid lines 112; the solder ribbon 12 is connected to the negative first grid line 111 and also to the negative second grid lines 112 that are not connected to the negative first grid line 111. Therefore, the solder ribbon 12 can collect the current collected by all the negative second grid lines 112.

[0046] At the head and tail of the battery string 1 along the first direction X, the bus bar 2 connected to the positive first grid line 111 is also connected to part of the positive second grid lines 112. The solder ribbon 12 covering the positive first grid line 111 can abut against or partially overlap with the conductive film 4, so that part of the current collected by the positive second grid lines 112 can directly flow to the bus bar 2, part can flow to the bus bar 2 through the positive first grid line 111, and part can flow to the bus bar 2 through the solder ribbon 12, thereby improving the current collection effect of the bus bar 2. The solder ribbon 12 covering the positive first grid line 111 can also not contact the conductive film 4, so that the length of the solder ribbon 12 can be shorter to reduce the cost of the back-contact photovoltaic module.

[0047] Similarly, the bus bar 2 connected to the negative first grid line 111 is also connected to part of the negative second grid lines 112. The solder ribbon 12 covering the negative first grid line 111 can abut against, partially overlap with, or not contact the conductive film 4.

[0048] Specifically, a plurality of insulating films 3 are provided, and a plurality of conductive films 4 are provided. The insulating films 3 and the conductive films 4 are arranged alternately, so that the insulating films 3 and the conductive films 4 can respectively correspond to the alternately arranged positive first grid lines 111 and negative first grid lines 111.

[0049] In the above embodiments, when the plurality of insulating films 3 and the plurality of conductive films 4 are arranged alternately, the width d2 of the insulating film 3 is equal to the width d3 of the conductive film 4, so that the insulating film 3 and the conductive film 4 can be cut by the same set of tooling, reducing the production cost of the insulating film 3 and the conductive film 4, and enabling the insulating film 3 and the conductive film 4 to be neatly arranged along the second direction Y when disposed on the battery cell 11, improving the appearance consistency of the back-contact photovoltaic module.

[0050] In the above embodiments, as Figure 4 shown, the insulating film 3 disposed on one battery cell 11 can be a continuous piece, thereby reducing the number of times of placing the insulating film 3 and improving the production efficiency of the back-contact photovoltaic module.

[0051] Specifically, as Figure 5 shown, the insulating film 3 is provided with an avoidance portion 31 penetrating through the insulating film 3 in the thickness direction of the battery cell 11, and the conductive film 4 is disposed in the avoidance portion 31. Wherein, the thickness direction of the battery cell 11 is perpendicular to the first direction X and the second direction Y.

[0052] When the bus bar 2 needs to be connected to the positive first grid line 111, the avoidance portion 31 on the insulating film 3 is arranged corresponding to the positive first grid line 111, so that the conductive film 4 can be in contact with the positive first grid line 111; when the bus bar 2 needs to be connected to the negative first grid line 111, the avoidance portion 31 on the insulating film 3 is arranged corresponding to the negative first grid line 111, so that the conductive film 4 can be in contact with the negative first grid line 111.

[0053] In one embodiment, the avoidance portion 31 penetrates through one side of the insulating film 3 along the first direction X. Optionally, the width d3 of the conductive film 4 is equal to the dimension of the avoidance portion 31 along the first direction X, so that when the conductive film 4 is placed in the avoidance portion 31, the conductive film 4 does not protrude from the edge of the insulating film 3 along the first direction X, and the appearance consistency of the back-contact photovoltaic module is relatively high. Optionally, the width d3 of the conductive film 4 is greater than the dimension of the avoidance portion 31 along the first direction X, so that when the conductive film 4 is placed in the avoidance portion 31, the conductive film 4 protrudes from the edge of the insulating film 3 along the first direction X, facilitating the connection between the conductive film 4 and the first grid line 111, and increasing the connection area between the conductive film 4 and the first grid line 111 and the contact area between the conductive film 4 and the bus bar 2, thereby reducing the loss of current during transmission. Preferably, the width d3 of the conductive film 4 is equal to the width d2 of the insulating film 3, so as to facilitate the connection between the conductive film 4 and the first grid line 111 while enabling the conductive film 4 and the insulating film 3 to be cut by a set of tooling.

[0054] In another specific embodiment, the avoidance portion 31 does not penetrate the insulating film 3 along the first direction X. Optionally, the width d3 of the conductive film 4 is equal to the dimension of the avoidance portion 31 along the first direction X, such that the conductive film 4 can just be placed within the avoidance portion 31. Optionally, the width d3 of the conductive film 4 is greater than the dimension of the avoidance portion 31 along the first direction X. When the conductive film 4 is placed within the avoidance portion 31, a part of the conductive film 4 can extend from the side of the insulating film 3 close to the cell 11 to between the insulating film 3 and the cell 11, so that the conductive film 4 is connected to the first grid line 111, and the width d3 of the conductive film 4 does not cause the conductive film 4 to protrude beyond the edge of the insulating film 3 along the first direction X, resulting in a relatively high appearance consistency of the back-contact photovoltaic module.

[0055] Furthermore, the width d3 of the conductive film 4 is greater than the dimension of the avoidance portion 31 along the first direction X, and the width d3 of the conductive film 4 is less than or equal to the width d2 of the insulating film 3. When the conductive film 4 is placed within the avoidance portion 31, a part of the conductive film 4 can cross the insulating film 3 from the side of the insulating film 3 close to or away from the cell 11 to be connected to the first grid line 111, and the width d3 of the conductive film 4 is not too wide, which will not cause excessive increase in the cost of the back-contact photovoltaic module. Preferably, the conductive film 4 can extend from the side of the insulating film 3 close to the cell 11 to between the insulating film 3 and the cell 11 and protrude beyond the edge of the insulating film 3, so that the contact area between the conductive film 4 and the first grid line 111 is increased, and thus the connection reliability between the conductive film 4 and the first grid line 111 is relatively high.

[0056] Furthermore, along the second direction Y, the conductive film 4 partially extends to the side of the insulating film 3 facing away from the cell 11, so that the conductive film 4 can be adhered to the insulating film 3, and thus the conductive film 4 and the insulating film 3 can be placed on the cell 11 together, simplifying the production steps of the back-contact photovoltaic module.

[0057] Specifically, along the second direction Y, the length L of the conductive film 4 satisfies: 0.2 mm ≤ L ≤ 1.5 mm. For example, the length L of the conductive film 4 can specifically be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc.

[0058] Along the second direction Y, the length L of the conductive film 4 should neither be too large nor too small. If the length L of the conductive film 4 is too small (e.g., less than 0.2 mm), when the conductive film 4 slightly deviates from the preset position, the conductive film 4 is likely to be disconnected from the first grid line 111, affecting the collection of current from the first grid line 111 by the bus bar 2. If the length of the conductive film 4 is too large (e.g., greater than 1.5 mm), the usage amount of the conductive film 4 in the back contact photovoltaic module is relatively large, and the cost of the back contact photovoltaic module is relatively high. Therefore, the length L of the conductive film 4 should be set within a reasonable range to prevent the conductive film 4 from being easily disconnected from the first grid line 111 while keeping the cost of the back contact photovoltaic module low.

[0059] It can be understood that along the second direction Y, the length of the insulating film 3 is longer than the length L of the conductive film 4 to better isolate the first grid line 111 and the second grid line 112 with different polarities.

[0060] In the above embodiments, the insulating film 3 can be an adhesive film, and the conductive film 4 can be an adhesive film. The insulating film 3 can also be a layered structure including an adhesive layer and an insulating layer, and the adhesive layer is disposed on the surface for contacting the battery chip 11. The conductive film 4 can also be a layered structure including a conductive adhesive layer and a conductive layer, and the conductive adhesive layer is disposed on the surface for contacting the battery chip 11.

[0061] In the above embodiments, the type of the back contact battery can be one of an interdigitated back contact (IBC) battery, a heterojunction back contact (HBC) battery, and a tunnel oxide back contact (TBC) battery.

[0062] The battery chip 11 can also be a back contact stacked battery, which includes a back contact bottom battery and a perovskite top battery. The perovskite top battery forms an electrical connection with the front surface of the back contact bottom battery. The back contact bottom battery can be the back contact battery described above. The perovskite top battery is a thin-film solar cell with a perovskite material as the photoactive layer. The structure of the perovskite top battery mainly consists of the following key parts: a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. These components work together to enable the perovskite top battery to effectively absorb sunlight and convert it into electrical energy. The perovskite material in the perovskite light-absorbing layer has excellent light absorption performance, can absorb a wider spectral range, and effectively convert short-wavelength spectra, making the perovskite top battery have a high photoelectric conversion efficiency.

[0063] In the above embodiments, as Figure 6As shown in the figure, the back-contact photovoltaic module includes: a front encapsulation structure 5, a front film layer 6, a battery string 1, a back film layer 7, and a back encapsulation structure 8. Among them, the front encapsulation structure 5, the front film layer 6, the back film layer 7, and the back encapsulation structure 8 encapsulate the battery string 1 to ensure that the back-contact photovoltaic module has high mechanical strength, reduce the impact of hail, wind, mechanical vibration, etc. on the back-contact photovoltaic module, and improve the sealing performance of the back-contact photovoltaic module, enhancing its corrosion resistance and safety.

[0064] Specifically, the front encapsulation structure 5 and the back encapsulation structure 8 can be one of rigid materials such as tempered glass, polyethylene terephthalate (PET), polycarbonate (PC), or one of flexible materials such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF). These materials have a high light transmittance, which can improve the photoelectric conversion efficiency of the back-contact photovoltaic module and ensure the power of the back-contact photovoltaic module. The front film layer 6 and the back film layer 7 can be one of materials such as ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), EVA-POE-EVA co-extruded film (EPE), EVA-POE co-extruded film (EP).

[0065] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back-contact photovoltaic module, characterized in that, The back-contact photovoltaic module comprises a cell string (1) and a bus bar (2), the cell string (1) comprises a cell sheet (11) and a welding ribbon (12), the welding ribbon (12) connects adjacent cell sheets (11), and the bus bar (2) connects adjacent cell strings (1); A first grid line (111) with a different polarity is arranged on the back of the battery cell (11), the bus bar (2) is arranged on the back of the battery cell (11), the first grid line (111) extends along a first direction (X), the bus bar (2) extends along a second direction (Y), and the second direction (Y) intersects with the first direction (X); An insulating film (3) is provided between the bus bar (2) and the first grid line (111) of one polarity, and a conductive film (4) is provided between the bus bar (2) and the first grid line (111) of another polarity, and the welding strip (12) has no direct contact with the bus bar (2).

2. The back-contact photovoltaic module according to claim 1, characterized in that, Along the first direction (X), a width d2 of the insulating film (3) is greater than a width d1 of the bus bar (2); And / or, along the first direction (X), the width d3 of the conductive film (4) is greater than the width d1 of the bus bar (2).

3. The back-contact photovoltaic module according to claim 2, wherein, The ratio of the width d2 of the insulating film (3) to the width d1 of the bus bar (2) satisfies: 1<d2 / d1≤2.

4. The back-contact photovoltaic module according to claim 1, wherein, The insulating film (3) is provided with a relief portion (31) penetrating the insulating film (3) along the thickness direction of the battery cell (11), and the conductive film (4) is arranged in the relief portion (31).

5. The back-contact photovoltaic module according to claim 4, wherein The avoidance portion (31) penetrates one side of the insulating film (3) along the first direction (X), and a width d2 of the insulating film (3) is equal to or greater than a dimension of the avoidance portion (31) along the first direction (X).

6. The back-contact photovoltaic module according to claim 1, wherein Along the second direction (Y), a plurality of the insulating films (3) are provided, a plurality of the conductive films (4) are provided, and the insulating films (3) and the conductive films (4) are arranged in an alternating manner.

7. The back-contact photovoltaic module according to claim 6, wherein The width d2 of the insulating film (3) is equal to the width d3 of the conductive film (4).

8. The back-contact photovoltaic module according to claim 1, characterized in that, Along the second direction (Y), the length L of the conductive film (4) satisfies: 0.2 mm ≤ L ≤ 1.5 mm.

9. The back-contact photovoltaic module according to any one of claims 2-8, characterized in that, A side of the welding strip (12) close to the bus bar (2) partially overlaps with the conductive film (4).

10. The back-contact photovoltaic module according to any one of claims 2-8, characterized in that, Along the second direction (Y), the conductive film (4) partially extends to a side of the insulating film (3) facing away from the battery cell (11).

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