Back contact photovoltaic module and photovoltaic system

Abstract

The utility model provides a back contact photovoltaic assembly and a photovoltaic system, and relates to the technical field of photovoltaic cells. According to the utility model, the back contact photovoltaic assembly is divided into the first battery string group and the second battery string group, and the middle bus bar is arranged between the first battery string group and the second battery string group for parallel connection. The chamfered edge of one back contact battery piece, closest to the middle bus bar, in each battery string included in the first battery string group faces the middle bus bar, and the right-angle edge of one back contact battery piece, closest to the middle bus bar, in each battery string included in the second battery string group faces the middle bus bar. It is ensured that a BC battery string reserved welding strip (namely a leading-out welding strip close to the bending position of the middle bus bar) composed of an even number of BC battery pieces with main grid anodes and cathodes arranged in a crossed mode is bent away from the middle bus bar, and the welding difficulty is reduced.

Description

Technical Field

[0001] The utility model mainly relates to the technical field of photovoltaic cells, and in particular to a back-contact photovoltaic module and a photovoltaic system. Background Art

[0002] The electrodes on the front or back of a photovoltaic cell are used to conduct internal current and can be divided into a main grid (busbar, BB) and a finger grid (also called a fine grid, or finger). The main grid primarily collects current from the finger grid and connects it in series, while the finger grid collects photogenerated carriers. Amidst the growing development and competition among various high-efficiency photovoltaic module technologies in the photovoltaic industry, BC (back contact) photovoltaic modules are highly sought after in the market for their unobstructed front grid lines, increased light-receiving area, high cell efficiency, and high module conversion efficiency. With the increasing demand for higher efficiency, the number of main grids in BC cells needs to be increased to improve current collection capacity.

[0003] The mainstream busbar count for BC-type cells is currently 18-20BB, with the positive and negative busbars arranged crosswise, that is, the positive and negative poles of the busbars are arranged crosswise. For BC cells with crosswise busbars, odd and even busbars affect the layout and layout of the component cells, as well as the aesthetic appearance. For BC cells with an even number of busbars and crosswise positive and negative poles, the distance between the outermost busbar and the short side of the cell is shorter. When the reserved welding strip at the end of the cell string is welded to the middle busbar, there is a bend in the middle busbar, which can easily affect the automatic welding of the reserved welding strip of the cell string (referring to the welding strip near the bend of the middle busbar) and the middle busbar by the stitching equipment. If the component layout is assembled into a whole piece, it is inevitable that the distance between the reserved welding strip at the end of the cell string and the bend of the middle busbar is relatively close, thus affecting the welding situation. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a back-contact photovoltaic module and a back-contact battery system, which can ensure that the reserved welding strips of the BC battery string composed of an even number of BC battery cells with cross-arranged main grid positive and negative poles are bent away from the middle bus bar, reducing the difficulty of welding.

[0005] In a first aspect, the present invention provides a back-contact photovoltaic module, comprising a first battery string group and a second battery string group, wherein an intermediate bus bar is provided between the first battery string group and the second battery string group for parallel connection; the first battery string group and the second battery string group each comprise at least one battery string, wherein the battery string comprises a plurality of back-contact battery cells connected in series along a direction perpendicular to the intermediate bus bar, wherein the back-contact battery cells comprise an even number of main grids, wherein the positive and negative poles of the even number of main grids are arranged crosswise, and the back-contact battery cells comprise oppositely arranged right-angled sides and chamfered sides,

[0006] The chamfered edge of a back contact battery cell closest to the middle bus bar in each battery string included in the first battery string group faces the middle bus bar;

[0007] In each battery string included in the second battery string group, a right-angled side of a back-contact battery cell closest to the middle bus bar faces the middle bus bar.

[0008] In a possible implementation, the first battery string group includes at least a first battery string, and the second battery string group includes at least a second battery string.

[0009] The back contact cells at both ends of the first cell string are respectively the first cell and the first cell, the first electrode of the first cell is led out, the second electrode of the first cell is led out, and the chamfered edge of the first cell faces outward away from the first cell;

[0010] The back contact cells at the first and last ends of the second cell string are respectively the second first cell and the second last cell, the second electrode of the second first cell is led out, the first electrode of the second last cell is led out, and the right angle side of the second first cell faces outward away from the second last cell;

[0011] The first electrode is one of a positive electrode and a negative electrode, and the second electrode is the other of the positive electrode and the negative electrode.

[0012] In a possible implementation, the first tail battery cell in the first battery string included in the first battery string group is arranged close to the middle bus bar, and the second head battery cell in the second battery string included in the second battery string group is arranged close to the middle bus bar.

[0013] In one possible implementation, the back-contact cells in the first cell string are assembled into a whole cell in pairs starting from the first tail cell; and the back-contact cells in the second cell string are assembled into a whole cell in pairs starting from a back-contact cell next to the second head cell.

[0014] In one possible implementation, the first battery string and the second battery string both include an even number of back-contact battery cells, the first battery string group is composed of the first battery string and the first battery string rotated 180 degrees, which are arranged crosswise, and the second battery string group is composed of the second battery string and the second battery string rotated 180 degrees, which are arranged crosswise.

[0015] In one possible implementation, the first battery string and the second battery string both include an odd number of back-contact battery cells, the first battery string group is composed of the first battery string and the second battery string arranged crosswise, the second battery string group is composed of the second battery string and the first battery string arranged crosswise, and the first battery cell of the first battery string and the second battery cell of the second battery string in the first battery string group and the second battery string group are arranged side by side.

[0016] In one possible implementation, the first cell string group and the second cell string group are located on a plane, the back-contact photovoltaic module further includes a stacked front glass, a front adhesive film, a back adhesive film and a back glass, and the first cell string group and the second cell string group are located between the front adhesive film and the back adhesive film.

[0017] In a second aspect, the present invention provides a photovoltaic system comprising the back-contact photovoltaic module described in the first aspect.

[0018] Compared with the prior art, the utility model has the following advantages:

[0019] The utility model divides the back-contact photovoltaic module into a first battery string group and a second battery string group. An intermediate bus bar is provided between the first battery string group and the second battery string group for parallel connection. The chamfered edge of a back-contact battery cell closest to the intermediate bus bar in each battery string included in the first battery string group is oriented toward the intermediate bus bar, and the right-angled edge of a back-contact battery cell closest to the intermediate bus bar in each battery string included in the second battery string group is oriented toward the intermediate bus bar, ensuring that the reserved welding strip (referring to the lead-out welding strip near the bend of the intermediate bus bar) of the BC battery string composed of an even number of BC battery cells with cross-arranged main grid positive and negative poles is kept away from the bend of the intermediate bus bar, thereby reducing the difficulty of welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the present invention. They are incorporated into and constitute a part of the present invention. The accompanying drawings illustrate embodiments of the present invention and, together with the specification, serve to explain the principles of the present invention. In the accompanying drawings:

[0021] Figure 1 This is a schematic diagram of a whole back contact solar cell provided by an embodiment of the present utility model;

[0022] Figure 2 This is a schematic diagram of the structure of a back-contact photovoltaic module provided by an embodiment of the present utility model;

[0023] Figure 3 This is a partially enlarged schematic diagram of a back-contact photovoltaic module provided by an embodiment of the present utility model;

[0024] Figure 4 This is a schematic diagram of a first battery string structure provided by an embodiment of the present utility model;

[0025] Figure 5 This is a schematic diagram of a second battery string structure provided by an embodiment of the present utility model. DETAILED DESCRIPTION

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly describes the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0027] As used herein, unless the context clearly indicates otherwise, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural. Generally speaking, the terms "include" and "comprising" only indicate the inclusion of the elements specifically identified, and these elements do not constitute an exclusive list; the device may also include other elements.

[0028] Unless otherwise specified, the relative arrangement and numerical values ​​of the parts described in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0029] In the description of the present invention, it needs to be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0030] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0031] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this utility model. Furthermore, while the terms used in this utility model are selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, it is required that this utility model be understood not only by the actual terms used, but also by the meaning implied by each term.

[0032] It should be understood that when a component is referred to as being “on,” “connected to,” “coupled to,” or “contacting” another component, it can be directly on, connected to, coupled to, or contacting the other component, or intervening components may be present. In contrast, when a component is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly contacting” another component, there are no intervening components present.

[0033] Currently in the field of photovoltaic cells, cells are usually assembled into battery strings first, and then the battery strings are assembled into photovoltaic modules. Figure 1 The shape of the entire back contact cell 100 is usually a rectangle with chamfered corners, such as Figure 1As shown in (a). The photovoltaic string welding machine loads the whole cell and then uses a laser to cut it into two halves. The cut edge corresponds to the right-angle edge, and the non-cut edge corresponds to the chamfered edge. Putting the whole cell together (that is, putting the two halves together to form a whole cell) means that the photovoltaic string welding machine needs to maintain the state of the whole cell when dicing, and cannot rotate one of the halves. In this way, the whole cell state can be maintained, but there is a gap in the middle. In the embodiment of the present invention, the two halves of the back contact cell 100 that are cut into can overlap after rotating 180 degrees, forming two identical back contact cells 101. There are several main grids on the back contact cell 101. The main grids are divided into cross-arranged positive main grids and negative main grids. The positive main grid is connected to the positive pole of the back contact cell 101, and the negative main grid is connected to the negative pole of the back contact cell 101. For the back contact cell 101 with an even number of main grids, the polarity of the main grids on the left and right sides is different. Please refer to Figure 1 (b) The polarity of the first busbar on the left side of the back contact cell 101 above, i.e., the first busbar 1011, and the first busbar on the right side, i.e., the second busbar 1012, are different. That is, when the first busbar 1011 is the positive busbar, the second busbar 1012 is the negative busbar, and when the first busbar 1011 is the negative busbar, the second busbar 1012 is the positive busbar.

[0034] According to the characteristics of the back contact cell with an even number of busbars, for example, 20 busbars, Figure 1 In (b), the top back-contact cell 101 has the 1st, 3rd, 5th, ..., 19th busbars from left to right, all of which are positive busbars, and the 2nd, 3rd, 4th, ..., 20th busbars are negative busbars; the bottom back-contact cell 101 has the 2nd, 3rd, 4th, ..., 20th busbars from left to right, all of which are positive busbars, and the 1st, 3rd, 5th, ..., 19th busbars are negative busbars. In the prior art, when connecting the back-contact cells 101 in series to form a battery string, the positive electrode of the first back-contact cell 101 is typically connected out, the negative electrode of the last back-contact cell 101 is connected out, and the middle back-contact cells 101 are connected in series to form a battery string A. PV modules are then constructed using cell strings A. Typically, one side of the center busbar (e.g., the top half of the module) consists of string A, string A rotated 180 degrees, string A, string A rotated 180 degrees, string A, string A rotated 180 degrees, all arranged side by side. The other side of the center busbar (e.g., the bottom half of the module) consists of string A rotated 180 degrees, string A, string A rotated 180 degrees, string A, string A rotated 180 degrees, all arranged side by side. Due to the cross-arrangement of the positive and negative poles of an even number of busbars, one of the two back-contact cells closest to the center busbar on either side will inevitably have its lead-out ribbon near the bend of the center busbar located at the very edge of the cell. This results in the lead-out ribbon being relatively close to the bend, thus affecting welding.

[0035] The purpose of the utility model is to provide a back-contact photovoltaic module to ensure that the reserved welding strip (referring to the lead-out welding strip near the bend of the middle bus bar) of the BC battery string composed of an even number of BC battery cells with cross-arranged main grid positive and negative poles is away from the bend of the middle bus bar, thereby reducing the difficulty of welding.

[0036] Figure 2 This is a schematic diagram of the back contact photovoltaic module structure provided by the embodiment of the present utility model. Figure 2 As shown, the back-contact photovoltaic module 200 includes a first battery string group 201 and a second battery string group 202. An intermediate bus bar 203 is provided between the first battery string group 201 and the second battery string group 202 for parallel connection. The first battery string group 201 and the second battery string group 202 are both composed of a plurality of battery strings arranged side by side. The battery strings include a plurality of back-contact battery cells 101 connected in series along a direction perpendicular to the intermediate bus bar 203 (vertical direction in the figure). Figure 3 As shown, the chamfered edge of the back contact cell closest to the middle bus bar 203 in each cell string included in the first cell string group 201 faces the middle bus bar 203, and the right-angled edge of the back contact cell closest to the middle bus bar in each cell string included in the second cell string group 202 faces the middle bus bar 203. In this way, according to the characteristic of the cross arrangement of the positive and negative electrodes of an even number of main grids, the two back contact cells closest to the middle bus bar 203 on both sides (such as Figure 3 The lead-out welding strips of the upper and lower back contact cells 101) near the bend of the middle bus bar 203 are not located at the edge of the cell, such as Figure 3 The arrow in the middle points out the welding strip. Figure 3 The arrow in the middle circle points to the bend of the middle bus bar, which can reduce the difficulty of welding by preventing the lead-out welding strip from being too close to the bend of the middle bus bar.

[0037] In some embodiments, the first battery string group 201 includes at least a first battery string, and the second battery string group 202 includes at least a second battery string. Figure 4 The back contact cells at the beginning and end of the first battery string 211 are the first cell 2111 and the first cell 2112, respectively. The positive electrode of the first cell 2111 is led out, and the negative electrode of the first cell 2112 is led out. The chamfered edge of the first cell 2112 faces outward away from the first cell 2111. Please refer to Figure 5The back-contact cells at the leading and trailing ends of the second battery string 212 are the leading second cell 2121 and the trailing second cell 2122, respectively. The negative electrode of the leading second cell 2121 is led outward, and the positive electrode of the trailing second cell 2122 is led outward. The right-angled edge of the leading second cell 2121 faces outward, away from the trailing second cell 2122. It should be understood that in other embodiments, the negative electrode of the leading first cell 2111 may be led outward, and the positive electrode of the trailing first cell 2112 may be led outward. Correspondingly, the positive electrode of the leading second cell 2121 may be led outward, and the negative electrode of the trailing second cell 2122 may be led outward.

[0038] When assembling the components, the first tail cell 2112 of the first cell string 211 included in the first cell string group 201 is arranged close to the middle bus bar 203, and the second first cell 2121 of the second cell string 212 included in the second cell string group 202 is arranged close to the middle bus bar 203. Furthermore, the back contact cells in the first cell string 211 are assembled into a whole piece in pairs starting from the first tail cell 2112, as shown in FIG. Figure 4 The back contact cells in the second cell string 212 are assembled into a whole cell in pairs starting from a back contact cell next to the second cell 2121. Figure 5 As shown, it is ensured that the back contact cells are assembled into a whole piece as much as possible to ensure the beautiful appearance of the photovoltaic module.

[0039] A battery string may be formed by an even number of back-contact battery cells connected in series, or an odd number of back-contact battery cells connected in series. In some embodiments, a battery string is formed by an even number of back-contact battery cells connected in series, such as Figure 4 (a) and Figure 5 As shown in (a), the first cell 2111 and the first cell 2112 of the first cell string 211 both have chamfered edges facing outward, and the cells therein can be assembled into a whole cell in pairs. The second cell 2121 and the second cell 2122 of the second cell string 212 both have right-angled edges facing outward, and except for the second cell 2121 and the second cell 2122, the cells in between can be assembled into a whole cell in pairs.

[0040] In this embodiment, the first battery string group 201 may be composed of a first battery string 211 and a first battery string 211 rotated 180 degrees and arranged in a cross pattern, and the second battery string group 202 may be composed of a second battery string 212 and a second battery string 212 rotated 180 degrees and arranged in a cross pattern. For example, please refer to Figure 2The upper portion of the center busbar 203 of the back-contact photovoltaic module 200 comprises a first cell string group 201. From left to right, the first cell string group 201 comprises a first cell string 211, a first cell string 211 rotated 180 degrees, a first cell string 211, a first cell string 211 rotated 180 degrees, a first cell string 211, and a first cell string 211 rotated 180 degrees. The lower portion of the center busbar 203 comprises a second cell string group 202. From left to right, the second cell string group 202 comprises a second cell string 212, a second cell string 212 rotated 180 degrees, a second cell string 212, a second cell string 212 rotated 180 degrees, a second cell string 212, and a second cell string 212 rotated 180 degrees. This embodiment ensures that the reserved cell string welding ribbons (referring to the lead-out welding ribbons near the bend of the center busbar) are away from the bend of the center busbar, reducing welding difficulty, while also ensuring an aesthetically pleasing and reasonable appearance of the photovoltaic module.

[0041] In some other embodiments, a battery string is formed by connecting an odd number of back-contact battery cells in series, such as Figure 4 (b) and Figure 5 As shown in (b), the first cell 2111 of the first battery string 211 has its right-angled edge facing outward, and the last cell 2112 has its chamfered edge facing outward. Except for the first cell 2111, all of the cells in the first battery string can be assembled into a complete cell in pairs. The second cell 2121 of the second battery string 212 has its right-angled edge facing outward, and the last cell 2122 has its chamfered edge facing outward. Except for the second cell 2121, all of the cells in the second battery string can be assembled into a complete cell in pairs.

[0042] In this embodiment, the first battery string group 201 may be composed of a first battery string 211 and a second battery string 212 arranged in a cross pattern, and the second battery string group 202 may be composed of a second battery string 212 and a first battery string 211 arranged in a cross pattern, and the first battery cell 2111 of the first battery string 211 and the second battery cell 2121 of the second battery string 212 in the first battery string group 201 and the second battery string group 202 are arranged side by side. For example, please refer to Figure 2 The upper portion of the middle busbar 203 of the back-contact photovoltaic module 200 comprises the first cell string group 201. From left to right, the first cell string group 201 comprises the first cell string 211, the second cell string 212, the first cell string 211, the second cell string 212, the first cell string 211, and the second cell string 212. The lower portion of the middle busbar 203 comprises the second cell string group 202. From left to right, the second cell string group 202 comprises the second cell string 212, the first cell string 211, the second cell string 212, the first cell string 211, the second cell string 212, and the first cell string 211. This embodiment ensures that the reserved cell string welding ribbons (referring to the lead-out welding ribbons near the bend of the middle busbar) are away from the bend of the middle busbar, reducing welding difficulty, while also ensuring an aesthetically pleasing and reasonable appearance of the photovoltaic module.

[0043] Furthermore, the first and second cell strings of the back-contact photovoltaic module are located on a single plane. The back-contact photovoltaic module also includes a stacked front glass, a front film, a back film, and a back glass, with the first and second cell strings located between the front film and the back film. That is, the back-contact photovoltaic module comprises, from front to back, the front glass, the front film, the cell string, the back film, and the back glass. Because the cells in the cell string are back-contact cells, there are no grid lines on the front, and the positive and negative grid lines are located on the back of the cells.

[0044] An embodiment of the present invention further provides a photovoltaic system, which includes the above-mentioned back-contact photovoltaic module.

[0045] The basic concepts have been described above. It will be apparent to those skilled in the art that the above disclosure of the utility model is merely illustrative and does not constitute a limitation of the present invention. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and revisions to the present invention. Such modifications, improvements, and revisions are suggested in the present invention and remain within the spirit and scope of the exemplary embodiments of the present invention.

[0046] At the same time, this utility model uses specific terms to describe the embodiments of the utility model. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic associated with at least one embodiment of the utility model. Therefore, it should be emphasized and noted that the mention of "one embodiment," "an embodiment," or "an alternative embodiment" two or more times in different places in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics of one or more embodiments of the utility model may be appropriately combined.

[0047] Similarly, it should be noted that, in order to simplify the presentation of the present disclosure and thus facilitate understanding of one or more embodiments of the present disclosure, the foregoing descriptions of the embodiments of the present disclosure sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not imply that the present disclosure requires more features than those mentioned. In fact, an embodiment may have fewer features than the total number of features of a single embodiment disclosed above.

[0048] Although the present invention has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions can be made without departing from the spirit of the present invention. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present invention, they will fall within the scope of the present invention.

Claims

1. A back contact photovoltaic module, characterized in that: The invention comprises a first battery string group and a second battery string group, wherein an intermediate bus bar is provided between the first battery string group and the second battery string group for parallel connection; the first battery string group and the second battery string group each comprise at least one battery string, wherein the battery string comprises a plurality of back-contact battery sheets connected in series along a direction perpendicular to the intermediate bus bar, wherein the back-contact battery sheets comprise an even number of main grids, wherein the positive and negative electrodes of the even number of main grids are arranged crosswise, and the back-contact battery sheets comprise oppositely arranged right-angled sides and chamfered sides, The chamfered edge of a back contact battery cell closest to the middle bus bar in each battery string included in the first battery string group faces the middle bus bar; In each battery string included in the second battery string group, a right-angled side of a back-contact battery cell closest to the middle bus bar faces the middle bus bar.

2. The back contact photovoltaic module according to claim 1, wherein: The first battery string group includes at least a first battery string, and the second battery string group includes at least a second battery string. The back contact cells at both ends of the first cell string are respectively the first cell and the first cell, the first electrode of the first cell is led out, the second electrode of the first cell is led out, and the chamfered edge of the first cell faces outward away from the first cell; The back contact cells at the first and last ends of the second cell string are respectively the second first cell and the second last cell, the second electrode of the second first cell is led out, the first electrode of the second last cell is led out, and the right angle side of the second first cell faces outward away from the second last cell; The first electrode is one of a positive electrode and a negative electrode, and the second electrode is the other of the positive electrode and the negative electrode.

3. The back contact photovoltaic module according to claim 2, wherein: The first tail battery cell in the first battery string included in the first battery string group is arranged close to the middle bus bar, and the second head battery cell in the second battery string included in the second battery string group is arranged close to the middle bus bar.

4. The back contact photovoltaic module according to claim 3, wherein: The back-contact cells in the first cell string are assembled into a whole cell in pairs starting from the first tail cell; the back-contact cells in the second cell string are assembled into a whole cell in pairs starting from a back-contact cell next to the second head cell.

5. The back contact photovoltaic module according to claim 4, characterized in that: The first battery string and the second battery string both include an even number of back-contact battery cells. The first battery string group is composed of the first battery string and the first battery string rotated 180 degrees, arranged crosswise. The second battery string group is composed of the second battery string and the second battery string rotated 180 degrees, arranged crosswise.

6. The back contact photovoltaic module according to claim 4, characterized in that: The first battery string and the second battery string both include an odd number of back-contact battery cells, the first battery string group is composed of the first battery string and the second battery string arranged crosswise, the second battery string group is composed of the second battery string and the first battery string arranged crosswise, and the first battery cell of the first battery string and the second battery cell of the second battery string in the first battery string group and the second battery string group are arranged side by side.

7. The back contact photovoltaic module according to claim 1, wherein: The first cell string group and the second cell string group are located on the same plane, and the back-contact photovoltaic module further comprises a stacked front glass, a front adhesive film, a back adhesive film and a back glass, and the first cell string group and the second cell string group are located between the front adhesive film and the back adhesive film.

8. A photovoltaic system, characterized in that: A back-contact photovoltaic module comprising the method according to any one of claims 1 to 7.

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