Back-contact solar cell string and method for manufacturing the same, assembly, and system

Abstract

The present invention is applied to the technical field of solar cells, and provides a back-contact solar cell string and its manufacturing method, assembly and system, the back-contact solar cell string includes at least two battery cells each including a P-type doped region and an N-type doped region arranged alternately, the P-type doped region is provided with a positive pole fine grid line, and the N-type doped region is provided with a negative pole fine grid line, and a plurality of conductive lines connecting the positive pole fine grid line and the negative pole fine grid line, and at the connection points of each conductive line and the positive pole fine grid line and the negative pole fine grid line, a conductive region for electrically connecting the conductive line and the positive pole fine grid line or the negative pole fine grid line, and an insulating region for insulatingly connecting the conductive line and the negative pole fine grid line or the positive pole fine grid line are alternately provided, and the conductive lines are regularly cut between adjacent battery cells. The back-contact solar cell string provided by the present invention solves the problems such as high cost due to the high usage of paste in the conventional battery cells and manufacturing difficulties due to the front-back bypass connection between each battery cell.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a back contact solar cell string, a manufacturing method thereof, an assembly, and a system.

Background Art

[0002] A solar cell is a semiconductor device that converts light energy into electrical energy. Low production costs and high energy conversion efficiency have consistently been the goals pursued by the solar cell industry. In conventional general solar cells, an emitter contact electrode and a base contact electrode are respectively disposed on the front and back surfaces of the battery cell. The front surface of the battery is the light-receiving surface, and due to the coating by the metal emitter contact electrode on the surface, a part of the incident sunlight is inevitably reflected and shielded by the metal electrode, causing some optical losses. The coating area by the surface metal electrode in a general crystalline silicon solar cell is about 7%. By reducing the surface coating by the metal electrode, the energy conversion efficiency of the battery can be directly increased. A back contact solar cell is a battery in which both the emitter contact electrode and the base contact electrode are disposed on the back surface (non-light-receiving surface) of the battery. There is no shielding by any metal electrode on the light-receiving surface of the battery, thereby effectively increasing the short-circuit current of the battery cell. At the same time, a wide metal grid line is possible on the back surface, reducing the series resistance and increasing the fill factor. In addition, such a battery without surface shielding not only has a high conversion efficiency but also looks beautiful. At the same time, the assembly of the all-back electrode is easier to assemble.

[0003] Conventional back-contact solar cells are assembled as an assembly through other processes after being connected in series as a cell string. In this series connection technology, the main grids of each polarity (N-type and P-type) are welded to the welding strips at the edges of the cell, and then the surface electrode (negative electrode) welding strip of one cell is welded to the back electrode (positive electrode) welding strip of the adjacent cell by a solder wire to connect the cells in series. Then, lead wires are welded to the positive and negative electrodes of the series-connected cell string to connect the cells to each other. However, due to the interval of the welding strips, the total efficiency of the solar cell decreases, and moreover, a large amount of silver paste needs to be consumed for the main grid, so the process cost of forming the main grid and welding strips on the cell increases. In addition, these welding strips wind around from the back surface of one cell to the surface of the adjacent next cell, which may cause manufacturing difficulties such as difficult alignment. On the other hand, since the cells are welded on one side, the problem of warping of the cells due to stress is likely to occur.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technical problem to be solved by the present invention is to provide a back-contact solar cell string that solves the problems of high cost due to high usage of paste in conventional cells and manufacturing difficulties due to front-back winding connection between cells.

Means for Solving the Problems

[0005] In order to solve the above technical problems, the present invention provides at least two cell units each including alternately arranged P-type doped regions and N-type doped regions, wherein a positive electrode fine grid line is provided in the P-type doped region, and a negative electrode fine grid line is provided in the N-type doped region; a plurality of conductive lines connecting the positive electrode fine grid line and the negative electrode fine grid line. At the connection points between each conductive wire and the positive electrode fine grid wire and the negative electrode fine grid wire, a conductive region for electrically connecting the conductive wire and the positive electrode fine grid wire or the negative electrode fine grid wire, and an insulating region for insulatingly connecting the conductive wire and the negative electrode fine grid wire or the positive electrode fine grid wire are alternately provided. Provided is a back contact solar cell string in which the conductive wires are regularly cut between two adjacent battery cells.

[0006] As an improvement of the above solution means, the conductive wire includes a first conductive wire and a second conductive wire. The first conductive wire is electrically connected to the positive electrode fine grid wire on the battery cell and the negative electrode fine grid wire on the adjacent battery cell in the conductive region. The first conductive wire is insulatingly connected to the negative electrode fine grid wire on the battery cell and the positive electrode fine grid wire on the adjacent battery cell in the insulating region. The second conductive wire is electrically connected to the negative electrode fine grid wire on the battery cell and the positive electrode fine grid wire on the adjacent battery cell in the conductive region. The second conductive wire is insulatingly connected to the positive electrode fine grid wire on the battery cell and the negative electrode fine grid wire on the adjacent battery cell in the insulating region.

[0007] As an improvement of the above solution means, the conductive wire includes a metal wire and a composite film that partially wraps the metal wire.

[0008] As an improvement of the above solution means, the conductive wire is a metal wire.

[0009] As an improvement of the above solution means, a conductive adhesive, solder paste or conductive adhesive tape is provided in the conductive region, or In the conductive region, the conductive wire and the positive electrode fine grid wire or the negative electrode fine grid wire are in direct contact and electrically connected.

[0010] As an improvement of the above solution means, the composite film is a POE film, an EVA film, a PVB film, or a co-extruded film made of POE and EVA.

[0011] As an improvement to the above solution, the positive electrode fine grid line or the negative electrode fine grid line is an aluminum grid line, a silver grid line, a copper grid line, or a silver-coated copper grid line.

[0012] As an improvement to the above solution, the positive electrode fine grid line includes alternately provided aluminum grid lines and silver grid lines, and the silver grid lines are connected to the conductive region.

[0013] As an improvement to the above solution, an insulator is provided in the insulating region.

[0014] As an improvement to the above solution, the same number of the second conductive lines corresponding to at least one of the first conductive lines are alternately provided.

[0015] As an improvement to the above solution, the first conductive line and the second conductive line are alternately provided, or two first conductive lines and two second conductive lines are alternately provided.

[0016] As an improvement to the above solution, between two adjacent battery cells, the same number of conductive lines are cut every first predetermined number of conductive lines.

[0017] As an improvement to the above solution, the first predetermined number is 1 to 4.

[0018] As an improvement to the above solution, the battery string further includes a conductive bus bar located at an end of the solar cell string, and the same number of conductive lines are electrically connected to the conductive bus bar every second predetermined number of conductive lines.

[0019] As an improvement to the above solution, the second predetermined number is 1 to 4.

[0020] Correspondingly, the present invention further provides a battery assembly including the back contact solar cell string described above.

[0021] Correspondingly, the present invention further provides a photovoltaic power generation system including the battery assembly described above.

[0022] Correspondingly, the present invention correspondingly disposing an insulator and a conductor on corresponding insulating regions and conductive regions connected to conductive wires on each positive electrode fine grid line and each negative electrode fine grid line of the battery cell, respectively; sequentially attaching each conductive wire to an insulator or a conductor disposed on the positive electrode fine grid line and the negative electrode fine grid line of each battery cell; and regularly cutting the conductive wire between two adjacent battery cells, and further provides a method for manufacturing a back contact solar cell string including the steps.

[0023] As an improvement of the above solution, the conductive wire includes a metal wire and a composite film partially wrapping the metal wire. After the step of sequentially attaching each conductive wire to the positive electrode fine grid line and the negative electrode fine grid line of each battery cell, or after the step of regularly cutting the conductive wire between two adjacent battery cells, the method further includes: preliminarily bonding the conductive wire and the battery cell by low-temperature heating.

[0024] As an improvement of the above solution, the method further includes: connecting the conductive wire to the positive electrode fine grid line and the negative electrode fine grid line of the battery cell by laminating and heating.

[0025] As an improvement of the above solution, the step of sequentially attaching each conductive wire to an insulator or a conductor disposed on the positive electrode fine grid line and the negative electrode fine grid line of each battery cell includes: alternately attaching a third predetermined number of first conductive wires and second conductive wires to an insulator or a conductor disposed on the positive electrode fine grid line and the negative electrode fine grid line of each battery cell. The first conductive wire is attached to conductors alternately arranged on each positive electrode fine grid wire in the battery cell, insulators alternately arranged on each negative electrode fine grid wire, conductors alternately arranged on each negative electrode fine grid wire in adjacent battery cells, and insulators alternately arranged on each positive electrode fine grid wire. The second conductive wire is attached to conductors alternately arranged on each positive electrode fine grid wire in the battery cell, insulators alternately arranged on each negative electrode fine grid wire, conductors alternately arranged on each negative electrode fine grid wire in adjacent battery cells, and insulators alternately arranged on each positive electrode fine grid wire.

[0026] As an improvement of the above solution means, the positive electrode fine grid wire includes alternately provided aluminum grid wires and silver grid wires, and the silver grid wires are connected to the conductive region.

[0027] As an improvement of the above solution means, the method regularly and electrically connects the conductive wire on the battery cell located at the end to the conductive bus bar, or electrically connecting each conductive wire on the battery cell located at the end to the conductive bus bar; and further includes regularly cutting the conductive wire between the battery cell and the conductive bus bar.

Advantages of the Invention

[0028] By implementing the present invention, the following beneficial effects are achieved. Instead of providing a main grid and welding strips for collecting the current of each battery cell, a plurality of continuous conductive wires are used to directly connect the positive electrode fine grid line or the negative electrode fine grid line on one battery cell to the corresponding negative electrode fine grid line or positive electrode fine grid line on the next adjacent battery cell, and the conductive wires between two battery cells are regularly cut to realize the series connection of each battery cell. Thereby, the use of silver paste by the main grid is reduced and the production cost is reduced. Further, since all the conductive wires are commonly arranged on the back surface of all the battery cells and directly connected to the positive electrode fine grid line and the negative electrode fine grid line, the operation difficulties such as the difficulty in alignment due to the need for a detour connection from the back surface of one battery cell to the front surface of the next battery cell in the past are avoided, and the problems such as the cost increase due to the high usage of paste of the conventional battery cell and the manufacturing difficulties due to the detour connection between the front and back surfaces of each battery cell are solved.

Brief Description of Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0030] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in more detail below by combining the drawings and embodiments. It should also be understood that the specific embodiments described herein are only for interpreting the present invention and are not intended to limit the present invention.

[0031] In the present invention, unless otherwise clearly defined or limited, terms such as "attach", "connect", "join", "fix", etc. should be understood in a broad sense. For example, they may be fixedly connected, removably connected, integrally connected, mechanically connected, electrically connected, directly connected, or even indirectly connected through an intermediate medium, and the interiors of two elements may be in communication. A person skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific situation. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0032] The present invention does not provide a main grid and welding strips for collecting the current of each battery cell. Instead, a plurality of continuous conductive wires are used to directly connect the positive electrode fine grid line or negative electrode fine grid line on one battery cell to the corresponding negative electrode fine grid line or positive electrode fine grid line on the adjacent next battery cell, and the conductive wires between two battery cells are regularly cut to realize the series connection of each battery cell, thereby reducing the use of silver paste for the main grid and reducing the production cost. In addition, since all the conductive wires are commonly arranged on the back surfaces of all the battery cells and directly connected to the positive electrode fine grid lines and negative electrode fine grid lines, the operational difficulties such as the need for detour connection from the back surface of one battery cell to the front surface of the next battery cell and the difficulty in alignment in the prior art are avoided, and problems such as the high cost due to the high usage of paste in the conventional battery cells and the manufacturing difficulties due to the front-back detour connection between each battery cell are solved.

[0033] Example 1 Referring to FIG. 1, which is a structural diagram of the back-contact solar cell string provided in the embodiment of the present invention, for the convenience of description, only the parts related to the embodiment of the present invention are shown. The back-contact solar cell string provided in the embodiment of the present invention is At least two battery cells each including P-type doped regions and N-type doped regions arranged alternately, wherein a positive electrode fine grid line 11 is provided in the P-type doped region and a negative electrode fine grid line 12 is provided in the N-type doped region, and a plurality of conductive lines connecting the positive electrode fine grid line 11 and the negative electrode fine grid line 12, At connection locations of each conductive line with the positive electrode fine grid line 11 and the negative electrode fine grid line 12, a conductive region for electrically connecting the conductive line with the positive electrode fine grid line 11 or the negative electrode fine grid line 12 and an insulating region for insulatingly connecting the conductive line with the negative electrode fine grid line 12 or the positive electrode fine grid line 11 are alternately provided, the conductive lines are regularly cut between adjacent battery cells.

[0034] In one embodiment of the present invention, the back contact solar cell string is a cell string formed by integrally connecting at least two battery cells (i.e., back contact solar cells) in series with each conductive line. The cell string may include two battery cells, three battery cells, or other multiple battery cells connected in series. Referring to FIGS. 1 to 3, a cell string formed by connecting two battery cells in series is shown. Referring to FIG. 4, in another embodiment of the present invention, a cell string formed by connecting three battery cells in series is shown. The cell string may further connect other numbers of battery cells in series according to actual usage requirements. Although not shown in the drawings, it can be understood that they are arranged according to actual requirements. The battery cells located at both ends of the cell string are defined as end battery cells. In the case of a cell string in which multiple battery cells are connected in series, the battery cells connected in series between the two end battery cells are defined as internal battery cells.

[0035] As an example of the present invention, the battery cell includes, from top to bottom, a surface passivation and antireflection layer, a silicon substrate, a back surface tunnel layer, alternately provided N-type doped regions and P-type doped regions, a back surface passivation layer, and battery electrodes in this order. Here, the N-type doped regions and the P-type doped regions are alternately provided on the lower surface of the back surface tunnel layer. The battery electrodes include a positive electrode fine grid line 11 and a negative electrode fine grid line 12. A contact is formed between the positive electrode fine grid line 11 and the P-type doped region, and a contact is formed between the negative electrode fine grid line 12 and the N-type doped region. In other embodiments of the present invention, the structure of the battery cell may be designed to be other structures and is not limited herein. However, it should be noted that in any structure of the battery cell, it is designed such that the positive electrode fine grid line 11 is provided in the P-type doped region and the negative electrode fine grid line 12 is provided in the N-type doped region.

[0036] Furthermore, in one embodiment of the present invention, as shown in FIG. 1 which is a back view of two adjacent battery cells to be connected in series, it includes the positive electrode fine grid line 11 and the negative electrode fine grid line 12 alternately provided in the P-type doped region and the N-type doped region. Each of the positive electrode fine grid line 11 and the negative electrode fine grid line 12 is alternately provided substantially parallel to the edge of the battery cell. Each battery cell is substantially rectangular. Here, the substantially rectangular battery cell may be, for example, a square or other rectangles, and may also have standard corners, cut corners, or rounded corners, which are set according to the actual manufacturing requirements and are not specifically limited herein. At the same time, the number of the positive electrode fine grid line 11 and the negative electrode fine grid line 12 is determined according to the actual size of the battery cell, the widths and distances of the positive electrode fine grid line 11 and the negative electrode fine grid line 12, and is not specifically limited herein. At the same time, it should be noted that two adjacent battery cells to be connected in series may be provided in an anti-symmetric manner, that is, the polarities of the fine grid lines provided in sequence may be set conversely. As shown in FIG. 1, in the first battery cell located on the left side, the negative electrode fine grid line 12 and the positive electrode fine grid line 11 are arranged in sequence from left to right, and in the adjacent second battery cell, the positive electrode fine grid line 11 and the negative electrode fine grid line 12 are arranged in sequence from left to right.

[0037] Furthermore, the positive electrode fine grid line 11 or the negative electrode fine grid line 12 is an aluminum grid line, a silver grid line, a copper grid line, or a silver-coated copper grid line. In an embodiment of the present invention, it can be understood that the positive electrode fine grid line 11 and the negative electrode fine grid line 12 may select grid lines of the same or different metal types. For example, both the positive electrode fine grid line 11 and the negative electrode fine grid line 12 select aluminum grid lines, or the positive electrode fine grid line 11 selects an aluminum grid line and the negative electrode fine grid line 12 selects a silver grid line. Here, when the positive electrode fine grid line 11 or the negative electrode fine grid line 12 is an aluminum grid line or a silver grid line, the aluminum grid line or the silver grid line is printed on the P-type doped region or the N-type doped region by screen printing. When the positive electrode fine grid line 11 or the negative electrode fine grid line 12 is a copper grid line, it is plated on the P-type doped region or the N-type doped region by methods such as electroplating or vapor deposition.

[0038] Furthermore, in an embodiment of the present invention, each conductive wire is connected to each of the positive electrode fine grid line 11 and the negative electrode fine grid line 12. Here, as described above, each of the positive electrode fine grid line 11 and the negative electrode fine grid line 12 on each battery cell is alternately provided parallel to the edge of the battery cell. Therefore, it can be determined that the optimal form for connecting each of the conductive wires to the positive electrode fine grid line 11 and the negative electrode fine grid line 12 is a vertical connection, that is, the conductive wire intersects each of the positive electrode fine grid line 11 and the negative electrode fine grid line 12 substantially perpendicularly. Of course, it can be understood that there may be corresponding deflection angles between each of the conductive wires and the positive electrode fine grid line 11 and the negative electrode fine grid line 12, rather than being perpendicular.

[0039] Furthermore, in one embodiment of the present invention, a conductive region and an insulating region are alternately provided at the connection points of the positive electrode fine grid lines 11 and the negative electrode fine grid lines 12 on each conductive line. In each conductive region, the conductive line is electrically connected to the fine grid lines of the same polarity, and in the insulating region, the conductive line is insulatively connected to the fine grid lines of the other polarity. For example, when the conductive line is connected to each of the positive electrode fine grid lines 11 in the conductive region, in the insulating region, it is connected to each of the negative electrode fine grid lines 12. In this case, the conductive line is electrically connected to each of the positive electrode fine grid lines 11 on the battery cell and insulatively connected to each of the negative electrode fine grid lines 12, thereby avoiding the conductive line being electrically connected to both the positive electrode fine grid lines 11 and the negative electrode fine grid lines 12 at the same time. Therefore, the conductive line functions as a positive electrode conductive line in the battery cell. Correspondingly, for the case where the conductive line is connected to each of the negative electrode fine grid lines 12 in the conductive region and insulatively connected to each of the positive electrode fine grid lines 11 in the insulating region, refer to the above description, and the redundant description is omitted here.

[0040] In the conductive region, a conductor such as a conductive adhesive, solder paste, or conductive adhesive tape is provided. The conductor is sandwiched between each conductive wire and the positive electrode fine grid line 11 and the negative electrode fine grid line 12. In this case, when connecting the conductive wire to the positive electrode fine grid line 11 and the negative electrode fine grid line 12 in the conductive region, the conductive wire is brazed or welded (e.g., laser welding) to the conductor in the conductive region, and the conductive wire is electrically connected to the positive electrode fine grid line 11 and the negative electrode fine grid line 12 through the conductor. Alternatively, in the conductive region, the conductive wire is in direct contact with the positive electrode fine grid line 11 or the negative electrode fine grid line 12 and is electrically connected. Accordingly, in the insulating region, an insulator 31 is provided. The insulator 31 may be a non-conductive adhesive tape or an insulating film, or may be other suitable non-conductive shield case or cover. The insulator 31 may include a material such as polypropylene or polyethylene, and may further include an acrylic-based adhesive layer. At the same time, the insulator 31 is sandwiched between each conductive wire and the positive electrode fine grid line 11 and the negative electrode fine grid line 12. In this case, when connecting the conductive wire to the positive electrode fine grid line 11 and the negative electrode fine grid line 12 in the insulating region, the insulator 31 insulates and separates the conductive wire from the positive electrode fine grid line 11 and the negative electrode fine grid line 12 from each other. Here, the shape of the conductor or the insulator 31 may be circular, square, triangular, or other shapes. The conductor or the insulator 31 may be used to achieve electrical connection or insulating connection between the conductive wire and the positive electrode fine grid line 11 and the negative electrode fine grid line 12, and its shape may be set according to the actual use requirements and is not specifically limited in this specification.

[0041] Furthermore, in an embodiment of the present invention, as shown in FIG. 1, the conductive wire includes a first conductive wire 21 and a second conductive wire 22. The first conductive wire 21 is electrically connected to the positive electrode fine grid line 11 on the battery cell and the negative electrode fine grid line 12 on the adjacent battery cell in the conductive region. The first conductive wire 21 is insulatingly connected to the negative electrode fine grid line 12 on the battery cell and the positive electrode fine grid line 11 on the adjacent battery cell in the insulating region. In the conductive region, the second conductive wire 22 is electrically connected to the negative electrode fine grid line 12 on the battery cell and the positive electrode fine grid line 11 on the adjacent battery cell. In the insulating region, the second conductive wire 22 is insulatingly connected to the positive electrode fine grid line 11 on the battery cell and the negative electrode fine grid line 12 on the adjacent battery cell.

[0042] It should be noted that in order to achieve a series connection between each battery cell, specifically, by connecting from each polar electrode of one battery to the other polar electrode of the next adjacent battery cell, the mutual connection of each battery cell is formed. For example, the back negative electrode of a battery cell is connected to the back positive electrode of the next adjacent battery cell. Therefore, in this embodiment, when performing a series connection of each battery cell by a conductive wire, when the conductive wire is electrically connected to each of the positive electrode fine grid lines 11 of one battery cell, it will necessarily be electrically connected to each of the negative electrode fine grid lines 12 (opposite polarity) of the next adjacent battery cell. Therefore, in this embodiment, the first conductive wire 21 and the second conductive wire 22 are provided, and the polarities of the fine grid lines electrically connected to the first conductive wire 21 and the second conductive wire 22 are opposite. As shown in FIG. 1, when the first conductive wire 21 is electrically connected to the positive electrode fine grid line 11 on the battery cell (right-side battery cell) and the negative electrode fine grid line 12 on the adjacent battery cell (left-side battery cell), the second conductive wire 22 is electrically connected to the negative electrode fine grid line 12 on the battery cell and the positive electrode fine grid line 11 on the adjacent battery cell. When there are three battery cells, the first conductive wire 21 is electrically connected to the positive electrode fine grid line 11 on one end battery cell, the negative electrode fine grid line 12 on the adjacent internal battery cell, and the positive electrode fine grid line 11 on the other adjacent end battery cell. In this case, the first conductive wire 21 functions as a positive electrode conductive wire in the end battery cell, but functions as a negative electrode conductive wire in the adjacent internal battery cell, thus realizing the series connection of the battery cells, and it can be understood that the current can flow from one battery cell to the next adjacent battery cell through the conductive wire and is finally led out.

[0043] Furthermore, in one embodiment of the present invention, the cross-section of the conductive wire may be circular, flat (e.g., strip-shaped), slightly flat, or other shapes. A circular conductive wire is preferred. At the same time, it should be pointed out that there is a possibility that the conductive wire may be crushed by other equipment and become flat during the period before and after connecting the battery cells in series through the conductive wire.

[0044] Furthermore, in one embodiment of the present invention, the conductive wire includes a metal wire and a composite film that partially wraps the metal wire. Here, the metal wire includes one conductive material (e.g., a metal such as copper or aluminum, or other suitable conductive materials with or without a coating of tin, silver, nickel, etc. or an organic solder wettability protection agent). In this embodiment, the metal wire is preferably a tin-coated copper wire. The composite film is coated on one end away from the positive electrode fine grid wire 11 and the negative electrode fine grid wire 12 of the metal wire, and the composite film is a POE film, an EVA film, a PVB film, or a co-extruded film made of POE and EVA. In this case, when connecting the battery cells in series through the conductive wire to form a battery string, the composite film on the conductive wire may be pre-bonded to the battery cell by low-temperature heating. Furthermore, when laminating the battery string as an assembly with devices such as glass and a backsheet, it is heated at the low temperature of lamination. The tin-coated copper wire can form a tin-silver alloy connection with the positive electrode fine grid wire 11 and the negative electrode fine grid wire 12, which are specifically silver grid wires. At the same time, the cured composite film after lamination can more tightly fix and connect the conductive wire and the positive electrode fine grid wire 11 and the negative electrode fine grid wire 12 on the battery cell, thereby solving the problem of warping of the battery cell due to stress in the case of one-sided welding of the back-contact battery. In other embodiments of the present invention, the conductive wire may further be a metal wire. In this case, the conductive wire is fixed by welding to the positive electrode fine grid wire 11 and the negative electrode fine grid wire 12 by any one of methods such as hot melt welding, laser welding, infrared welding, or electromagnetic welding.

[0045] The P-type doped region mostly requires using aluminum grid lines as the positive electrode fine grid lines 11. However, when the conductive wire is a copper wire partially wrapped by a copper wire or a composite film, welding between aluminum and copper is difficult, making it impossible to successfully weld the conductive wire and the positive electrode fine grid lines 11. Therefore, in a preferred embodiment of the present invention, the positive electrode fine grid lines 11 include alternately provided aluminum grid lines and silver grid lines. Here, the silver grid lines are connected to the conductive region. That is, when screen-printing the positive electrode fine grid lines 11 on the battery cell, the aluminum grid lines and the silver grid lines are printed in a stepped intersection manner. The silver grid lines are printed at the locations of the conductive region where it is necessary to electrically connect the positive electrode fine grid lines 11 to the conductive wire, and the aluminum grid lines are printed at other locations not connected to the conductive wire. Since the silver grid lines can be better welded to the conductive wire, the problem that the entire positive electrode fine grid lines 11 cannot be successfully welded to the conductive wire using aluminum grid lines is avoided.

[0046] Furthermore, in an embodiment of the present invention, the same number of second conductive wires 22 corresponding to at least one first conductive wire 21 are alternately provided. In a preferred embodiment of the present invention, the first conductive wire 21 and the second conductive wire 22 are alternately provided, or two first conductive wires 21 and two second conductive wires 22 are alternately provided. In other embodiments of the present invention, several (for example, three) other first conductive wires 21 and the corresponding several (for example, three) second conductive wires 22 may be alternately provided, and it can be understood that it is set according to the actual number of conductive wires required and the required arrangement method, and is not specifically limited in this specification. As shown in FIG. 1, the first conductive wire 21 and the second conductive wire 22 are alternately provided. On the one hand, as shown in FIG. 2, two first conductive wires 21 and two second conductive wires 22 are alternately provided. On the other hand, as shown in FIG. 3, three first conductive wires 21 and three second conductive wires 22 are alternately provided.

[0047] Furthermore, in one embodiment of the present invention, as shown in FIG. 1, the first conductive line 21 connects the positive electrode fine grid line 11 (positive electrode) of the battery cell (right battery cell) to the negative electrode fine grid line 12 (negative electrode) of the adjacent battery cell (left battery cell), and the second conductive line 22 connects the negative electrode fine grid line 12 of the battery cell to the positive electrode fine grid line 11 of the adjacent battery cell. Therefore, if the connection between the first conductive line 21 and the second conductive line 22 is not cut off, the two battery cells will be short-circuited. Therefore, it is necessary to cut one of the first conductive line 21 and the second conductive line 22 between two predetermined battery cells to enable recovery to independent positive and negative electrodes, thereby realizing the front-to-back series connection between each battery cell, that is, the negative electrode of each battery cell is connected to the positive electrode of the adjacent battery cell to realize series connection. At the same time, the current also flows from the negative electrode to the positive electrode inside each battery cell. Therefore, in one embodiment of the present invention, between two adjacent battery cells, the same number of conductive lines are cut off every first predetermined number of conductive lines. Here, the first predetermined number is 1 to 4.

[0048] Preferably, the first predetermined number of conductive lines to be separated should correspond to the number of a plurality of alternately provided first conductive lines 21 and second conductive lines 22. As shown in FIG. 1, when the first conductive line 21 and the second conductive line 22 are alternately provided, one conductive line is cut off every other one accordingly. As shown in FIG. 2, when two first conductive lines 21 and two second conductive lines 22 are alternately provided, two conductive lines are cut off every other two accordingly. As shown in FIG. 3, when three first conductive lines 21 and three second conductive lines 22 are alternately provided, three conductive lines are cut off every other three accordingly. Preferably, the plurality of conductive lines cut off at intervals between two battery cells are of the same type of conductive line, and as shown in FIGS. 1 to 3, all the first conductive lines 21 are cut off.

[0049] Meanwhile, as shown in FIG. 1, since the battery string is formed by connecting two battery cells in series, all the first conductive wires 21 are regularly cut between the two battery cells. In this case, the current at the negative electrode fine grid line 12 of the left battery cell flows from the inside of the left battery cell to the adjacent positive electrode fine grid line 11. The positive electrode fine grid line 11 is electrically connected to the second conductive wire 22. In this case, the current at the positive electrode fine grid line 11 of the left battery cell is passed through the second conductive wire 22 to the negative electrode fine grid line 12 of the right battery cell, flows through the inside of the right battery cell to the adjacent positive electrode fine grid line 11, and finally forms a series connection of the battery cells. When the battery string is formed by connecting three or more battery cells in series, as shown in FIG. 4, all the first conductive wires 21 are cut between the end battery cell located on the left and the internal battery cell located in the middle, and all the second conductive wires 22 are cut between the internal battery cell located in the middle and the end battery cell located on the right. Therefore, the current flow direction is: negative electrode fine grid line 12 of the left end battery cell → positive electrode fine grid line 11 → second conductive wire 22 → negative electrode fine grid line 12 of the internal battery cell → positive electrode fine grid line 11 → first conductive wire 21 → negative electrode fine grid line 12 of the right end battery cell → positive electrode fine grid line 11. Therefore, based on the actual number of battery cells connected in series and the specific current flow direction formed after the series connection, the conductive wires that need to be cut between each battery cell are determined. In the case of a battery string composed of four battery cells, the first conductive wire 21 is cut between the end battery cell located on the left and the internal battery cell located in the middle, the second conductive wire 22 is cut between the two internal battery cells located in the middle, and all the first conductive wires 21 are cut between the internal battery cell located in the middle and the end battery cell located on the right. When one type of conductive wire (for example, the first conductive wire 21) is cut between a battery cell and the adjacent battery cell connected on the left, the other type of conductive wire (for example, the second conductive wire 22) is cut between the battery cell and the adjacent battery cell connected on the right.

[0050] Furthermore, in one embodiment of the present invention, the battery string further includes a conductive bus bar 41 located at the end of the solar cell string, and the same number of conductive wires are connected to the conductive bus bar 41 every second predetermined number of conductive wires. The second predetermined number is 1 to 4. Here, the second predetermined number corresponds to the first predetermined number. Specifically, there are two conductive bus bars 41, which are respectively located at both ends of two end battery cells and are used as the two electrodes of the entire battery string. That is, the current led to each of the positive electrode fine grid line 11 and the negative electrode fine grid line 12 in each battery cell is aggregated to the conductive bus bar 41 via the conductive wire. As shown in FIG. 1, the conductive bus bar 41 located on the left side is used as the negative electrode terminal, and the conductive bus bar 41 located on the right side is used as the positive electrode terminal. Since the first conductive wire 21 and the second conductive wire 22 are electrically connected to the positive electrode fine grid line 11 and the negative electrode fine grid line 12 with opposite polarities respectively, the conductive bus bar 41 needs to be connected to a single positive electrode fine grid line 11 or negative electrode fine grid line 12 in the end battery cell. First, all the conductive wires of the two end battery cells of the battery string need to be cut, and then the conductive wires to be connected can be regularly and electrically connected to the conductive bus bar 41. Or first, all the conductive wires of the end battery cell can be connected to the conductive bus bar 41, and then the conductive wires connected to the conductive bus bar 41 can be regularly cut. That is, the same number of conductive wires are electrically connected to the conductive bus bar 41 every second predetermined number of conductive wires. As shown in FIG. 1, when the first conductive wire 21 and the second conductive wire 22 are alternately arranged and all the first conductive wires 21 are cut at intervals, one out of every two conductive wires is connected to the conductive bus bar 41. That is, all the first conductive wires 21 in the end battery cell located at the left end are electrically connected to the negative electrode conductive bus bar 41 at the left end, and all the first conductive wires 21 in the end battery cell located at the right end are electrically connected to the positive electrode conductive bus bar 41 at the right end. As shown in FIG. 2, when two first conductive wires 21 and two second conductive wires 22 are alternately provided and all the first conductive wires 21 are cut at intervals, two out of every two conductive wires are electrically connected to the conductive bus bar 41.Finally, in order to connect all the conductive wires (the first conductive wire 21 as shown in FIGS. 1 to 4) connected to the negative electrode fine grid wire 12 in one of the end battery cells to the negative electrode conductive bus bar 41, all the conductive wires (the first conductive wire 21 as shown in FIGS. 1 to 3 and the second conductive wire 22 as shown in FIG. 4) connected to the positive electrode fine grid wire 11 in the other end battery cell are connected to the positive electrode conductive bus bar 41. Specifically, reference may be made to FIGS. 1 to 4.

[0051] In an embodiment of the present invention, a main grid and a welding strip for collecting the current of each battery cell are not provided. A plurality of continuous conductive wires are used to directly connect the positive electrode fine grid wire or the negative electrode fine grid wire on one battery cell to the corresponding negative electrode fine grid wire or positive electrode fine grid wire on the adjacent next battery cell, and the conductive wires between the two battery cells are regularly cut to realize the series connection of each battery cell. Thereby, the use of the silver paste of the main grid is reduced and the production cost is reduced. Further, since the conductive wires are commonly arranged on the back surfaces of all the battery cells and are directly connected to the positive electrode fine grid wire and the negative electrode fine grid wire, the operation difficulties such as the need for a detour connection from the back surface of one battery cell to the front surface of the next battery cell, which are difficult to align, are avoided, and the problems such as the high cost due to the high usage amount of the paste of the conventional battery cell and the manufacturing difficulties due to the front-back detour connection between each battery cell are solved. In addition, when the conductive wire uses a metal wire and a composite film partially wrapping the metal wire, the composite film can wrap the metal wire, the positive electrode fine grid wire, and the negative electrode fine grid wire by being heated and melted after preheating. At the same time, by the low-temperature lamination process, a uniform and tight integration is formed between the positive electrode fine grid wire, the negative electrode fine grid wire, the metal wire, and the composite film, and a tin-silver alloy connection is further formed between the metal wire using a tin-coated copper wire and the positive electrode fine grid wire and the negative electrode fine grid wire using a silver grid wire. Therefore, the problem of warping due to the stress of the battery cell is solved.

[0052] Example 2 Referring to FIG. 5 which is a flowchart of a method for manufacturing a back-contact solar cell string provided in the second embodiment of the present invention, for the convenience of description, only the parts related to the embodiments of the present invention are shown. The manufacturing method is used to manufacture the back-contact solar cell string described in the above embodiments, and specifically includes the following S11, S21, and S31.

[0053] In step S11, an insulator and a conductor are respectively arranged corresponding to the corresponding insulating regions and conductive regions connected to the conductive lines on each positive electrode fine grid line and each negative electrode fine grid line in the battery cell.

[0054] As shown in FIGS. 1 to 4, positive electrode fine grid lines and negative electrode fine grid lines are respectively provided in the N-type doped regions and P-type doped regions alternately provided in the battery cell. For example, as shown in FIG. 1, in the end battery cell located on the left side, negative electrode fine grid lines and positive electrode fine grid lines are alternately provided in order from the left. In the end battery cell located on the right side, positive electrode fine grid lines and negative electrode fine grid lines are alternately provided in order from the left. In this case, each positive electrode fine grid line on the battery cell needs to be electrically connected to one conductive wire, and each negative electrode fine grid line is insulatedly connected to the conductive wire, so that the conductive wire functions as a positive electrode conductive wire in the battery cell. Correspondingly, each positive electrode fine grid line on the battery cell needs to be insulatedly connected to one conductive wire, and each negative electrode fine grid line is electrically connected to the conductive wire, so that the conductive wire functions as a negative electrode conductive wire in the battery cell. It is necessary to alternately provide an insulator and a conductor in order in the insulating region and the conductive region at the connection positions between the conductive wire and the positive electrode fine grid line and the negative electrode fine grid line. As shown in FIG. 1, the first conductive wire located at the uppermost end is electrically connected to the negative electrode fine grid line of the end battery cell located on the left side and is insulatedly connected to the positive electrode fine grid line. Therefore, at the connection position corresponding to the first conductive wire of the end battery cell, a conductor is applied to the conductive region corresponding to each negative electrode fine grid line, and an insulator is applied to the insulating region corresponding to each positive electrode fine grid line. The rest is as described above, and redundant explanations are omitted here. Correspondingly, the conductor may be a conductive material such as a conductive adhesive, solder paste or conductive adhesive tape, and the insulator may be an insulating material such as polypropylene or polyethylene. Since the conductive wire itself can be electrically connected to the positive electrode fine grid line or the negative electrode fine grid line in the conductive region, in other embodiments of the present invention, the conductor may not be arranged in the conductive region. Correspondingly, it can be understood that when applying the conductor, the electrical connection and physical connection between the conductive wire and the positive electrode fine grid line and the negative electrode fine grid line can be made more stable. On the other hand, since the insulator is used for the insulating connection in the insulating region between the conductive wire and the positive electrode fine grid line or the negative electrode fine grid line, it must be arranged.

[0055] It should be noted that the conductor and the insulator are preferably pre-coated and arranged alternately on the positive electrode fine grid line and the negative electrode fine grid line. In other embodiments of the present invention, they may be pre-coated and arranged alternately on the conductive wire, and it is only necessary to be used mainly to realize electrical connection and insulating connection when connecting the conductive wire with the positive electrode fine grid line and the negative electrode fine grid line.

[0056] In step S21, each conductive wire is sequentially attached to the insulator or conductor arranged on the positive electrode fine grid line and the negative electrode fine grid line of each battery cell.

[0057] The above step of sequentially attaching each conductive wire to the insulator or conductor arranged on the positive electrode fine grid line and the negative electrode fine grid line of each battery cell specifically includes: a step of alternately attaching a third predetermined number of first conductive wires and second conductive wires to the insulator or conductor arranged on the positive electrode fine grid line and the negative electrode fine grid line of each battery cell, The first conductive wire is attached to the conductor alternately arranged on each positive electrode fine grid line in the battery cell, the insulator alternately arranged on each negative electrode fine grid line, the conductor alternately arranged on each negative electrode fine grid line in the adjacent battery cell, and the insulator alternately arranged on each positive electrode fine grid line, The second conductive wire is attached to the conductor alternately arranged on each positive electrode fine grid line in the battery cell, the insulator alternately arranged on each negative electrode fine grid line, the conductor alternately arranged on each negative electrode fine grid line in the adjacent battery cell, and the insulator alternately arranged on each positive electrode fine grid line.

[0058] Furthermore, in the P-type doped region, although it is almost necessary to use an aluminum grid line as the positive electrode fine grid line, when the conductive line is a copper line partially wrapped with a copper wire or a composite film, it is difficult to weld aluminum and copper, so that the conductive line and the positive electrode fine grid line cannot be welded well. Therefore, in a preferred embodiment of the present invention, the positive electrode fine grid line may further include alternately provided aluminum grid lines and silver grid lines. In this case, the silver grid line is connected to the conductive region, that is, a conductor is correspondingly arranged on the silver grid line provided on the positive electrode fine grid line, so that the silver grid line and the conductive line can be welded well, thereby avoiding the problem that the entire positive electrode fine grid line cannot be welded well with the conductive line using the aluminum grid line.

[0059] In step S31, the conductive lines between two adjacent battery cells are regularly cut.

[0060] To collect the current from the battery string, the conductive wire between two adjacent battery cells is cut to achieve a series connection between each battery cell. The cutting of the conductive wire may be performed using a wire cutting technique such as a laser or a blade. Specifically, the number of conductive wires between two adjacent battery cells that are regularly cut is the same as the number of the first conductive wires and the second conductive wires provided alternately. That is, when the third predetermined number of the first conductive wires and the third predetermined number of the second conductive wires are provided alternately, the third predetermined number of conductive wires between two adjacent battery cells are regularly cut correspondingly every third predetermined number of conductive wires. As shown in the structure of the foregoing embodiment, specifically, all the first conductive wires or all the second conductive wires in two adjacent battery cells may be cut. The step of cutting the conductive wire between two adjacent battery cells is mainly used to realize that when each battery cell is connected in series, the current of the previous battery cell flows to the adjacent current battery cell and also flows from the current battery cell to the adjacent next battery cell, so as to sequentially connect each battery cell in series to form a battery string. Accordingly, based on the specifically arranged number of battery cells and their arrangement manner, it is necessary to correspondingly determine the conductive wires that need to be regularly cut so that the current can flow in sequence from the start end of one end battery cell to the end of the other end battery cell, which is not specifically limited in this specification.

[0061] Furthermore, as described in the foregoing embodiment, the conductive wire may include a metal wire and a composite film that partially wraps the metal wire. In this case, after the above step S21 or after step S31, the method further includes a step of pre-bonding the conductive wire and the battery cell by low-temperature heating.

[0062] During the manufacture of the battery string, since the conductive wire further includes a composite film that partially wraps the metal wire, the composite film is heated by low-temperature heating to be melted, and the melted composite film can entirely wrap the conductive wire, the battery cell, and the conductor or insulator provided between the conductive wire and the battery cell, thereby realizing preliminary adhesion between the conductive wire and the battery cell. It can be understood that the low-temperature heating step may be set after step S21 or after step S31. Here, it is preferably set after step S21. After the conductive wire and the battery cell are preliminarily adhered by low-temperature heating, the connection between the conductive wire and each battery cell becomes relatively reliable. Therefore, in the process of cutting the conductive wire between two adjacent battery cells subsequently, the problem of displacement caused by the unstable connection between the conductive wire and each battery cell can be avoided.

[0063] Furthermore, in an embodiment of the present invention, after the step S31, the method further includes a step of connecting the conductive wire to the positive electrode fine grid wire and the negative electrode fine grid wire of the battery cell by laminating heating.

[0064] During the manufacture of the battery assembly, it is necessary to integrally bond multiple layers of different materials such as the laminated and laid battery string and glass, EVA film / POE film, backsheet, etc. by a lamination process. Therefore, the lamination heating step may be performed in the subsequent assembly manufacturing process. Naturally, first, the battery cell and the conductive wire are uniformly and tightly formed into one body by lamination heating, and during the manufacture of the subsequent battery assembly, the battery string, glass, EVA film / POE film, backsheet, etc. may be integrally bonded by subsequent lamination heating.

[0065] Lamination refers to a method of integrally bonding two layers or multiple layers of the same or different materials under heating and pressure, with or without using an adhesive. During the lamination heating (heating temperature is less than 200 °C), the composite film that partially wraps the metal wire is uniformly heated and begins to melt, and under the action of pressure, the conductive wire and the positive electrode fine grid wire or the negative electrode fine grid wire are melted and uniformly and tightly bonded into one body. At the same time, the metal wire and the positive electrode fine grid wire or the negative electrode fine grid wire form a tin-silver alloy connection.

[0066] Furthermore, in one embodiment of the present invention, after the step S31, the method regularly and electrically connects the conductive wires on the battery cells located at the ends to the conductive bus bars, or or electrically connects each conductive wire on the battery cells located at the ends to the conductive bus bars, and further includes regularly cutting the conductive wires between the battery cells and the conductive bus bars.

[0067] After step S31, by connecting the conductive wires on the end battery cells in the battery string to the conductive bus bars, it is realized that the currents collected by each battery cell are finally merged into the conductive bus bars to form the battery string. For the above steps, specific reference may be made to the foregoing description, and it is understandable that duplicate descriptions are omitted here.

[0068] The manufacturing method of the back-contact solar cell string provided in the embodiment of the present invention does not provide a main grid and welding strips for collecting the current of each battery cell. Instead, a plurality of continuous conductive wires are used to directly connect the positive fine grid line or negative fine grid line on one battery cell to the corresponding negative fine grid line or positive fine grid line on the adjacent next battery cell, and by regularly cutting the conductive wires between two battery cells, the series connection of each battery cell is realized, thereby reducing the use of silver paste for the main grid and reducing the production cost. In addition, since the conductive wires are commonly arranged on the back surfaces of all battery cells and are directly connected to the positive fine grid lines and negative fine grid lines, the operational difficulties such as the need for detour connection from the back surface of one battery cell to the front surface of the next battery cell, which is difficult to align, are avoided, and the problems such as the high cost due to the high usage of paste of the conventional battery cells and the manufacturing difficulties due to the front-back detour connection between each battery cell are solved.

[0069] Example 3 The third embodiment of the present invention further provides a battery assembly, which includes the back-contact solar cell string described in the above embodiments.

[0070] Specifically, the assembly process of the battery assembly includes the following process.

[0071] In battery sorting, since the production line of solar cells has high randomness, the performance of the produced batteries is not always the same. In order to effectively combine battery cells with consistent or similar performance, they are classified according to the performance parameters measured by battery testing, so as to improve the utilization rate of battery cells and manufacture battery assemblies with qualified quality. Battery testing is to measure the magnitudes of the output parameters (current and voltage) of the battery.

[0072] In series connection, each conductive wire attached to each battery cell is fixed to the positive electrode fine grid wire and the negative electrode fine grid wire of the battery cell respectively, and the conductive wire between two adjacent battery cells is regularly cut, so as to connect in series as the battery string described in the above embodiments.

[0073] In lamination, after being connected in series on the back and passing the inspection, glass, cut EVA film / POE film, battery string, EVA film / POE film, glass fiber, and backsheet / glass are sequentially laid from bottom to top. When laying, the relative positions of the battery string and materials such as glass are guaranteed, and the distance between battery cells is adjusted.

[0074] In assembly lamination, the laminated battery cells are put into a laminator, evacuated to remove the air in the assembly, then heated to melt the EVA to bond the battery, glass, and backsheet together, and finally cooled to take out the assembly.

[0075] In burr removal, during lamination, after the EVA melts, it extends outward under pressure and hardens to form burrs, so the burrs are removed after lamination.

[0076] In the frame implementation, an aluminum frame is implemented in the assembly to enhance the strength of the assembly, further seal the battery assembly, and extend the service life of the battery. Here, the gap between the frame and the glass assembly is filled with silicone resin, and the corners between the frames are connected with corner keys.

[0077] In the wiring box adhesion, to facilitate the connection of the battery to other equipment or batteries, a box is adhered to the lead wires on the back surface of the assembly.

[0078] In the assembly test, the output power of the battery is tested and calibrated, its output characteristics are measured, and the quality level of the assembly is determined.

[0079] In the high-voltage test, to protect the assembly from adverse natural conditions (such as lightning strikes, etc.), a certain voltage is applied between the assembly frame and the electrode lead wire, and the electric resistance and insulation strength of the assembly are measured.

[0080] The battery assembly provided in the embodiment of the present invention does not provide a main grid and welding strips for collecting the current of each battery cell in the battery string. Instead, a plurality of continuous conductive wires are used to directly connect the positive electrode fine grid wire or negative electrode fine grid wire on one battery cell to the corresponding negative electrode fine grid wire or positive electrode fine grid wire on the adjacent next battery cell, and by regularly cutting the conductive wires between the two battery cells, the series connection of each battery cell is realized, thereby reducing the use of the silver paste of the main grid and reducing the production cost. In addition, since the conductive wires are commonly arranged on the back surfaces of all battery cells and are directly connected to the positive electrode fine grid wire and the negative electrode fine grid wire, the operational difficulties such as the difficulty in alignment due to the need for a detour connection from the back surface of one battery cell to the front surface of the next battery cell in the prior art are avoided, and problems such as the cost increase due to the high usage of the paste of the conventional battery cell and the manufacturing difficulties due to the front-back detour connection between each battery cell are solved.

[0081] Example 4 The fourth embodiment of the present invention further provides a photovoltaic power generation system including the battery assembly described in the above embodiment.

[0082] The photovoltaic power generation system provided in the embodiment of the present invention does not provide a main grid and welding strips for collecting the current of each battery cell in the battery string in the battery assembly, but uses a plurality of continuous conductive wires to connect the positive electrode fine grid line or negative electrode fine grid line on one battery cell directly to the corresponding negative electrode fine grid line or positive electrode fine grid line on the adjacent next battery cell, and by regularly cutting the conductive wire between two battery cells, the series connection of each battery cell is realized, thereby reducing the use of the silver paste of the main grid and reducing the production cost. In addition, since all the conductive wires are commonly arranged on the back surfaces of all the battery cells and are directly connected to the positive electrode fine grid line and the negative electrode fine grid line, the operational difficulties such as the difficulty of alignment due to the need for a detour connection from the back surface of one battery cell to the front surface of the next battery cell in the prior art are avoided, and the problems such as the high cost due to the high usage of the paste of the conventional battery cell and the manufacturing difficulties due to the front-back detour connection between each battery cell are solved.

[0083] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Modifications, equivalent replacements, improvements, etc. made without departing from the spirit and principle of the present invention are all included within the protection scope of the present invention.

Claims

1. At least two battery cells each including alternately arranged P-type doped regions and N-type doped regions, wherein a positive electrode fine grid line is provided in the P-type doped region and a negative electrode fine grid line is provided in the N-type doped region; at least two battery cells, a plurality of conductive wires connecting the positive electrode fine grid line and the negative electrode fine grid line, between two adjacent battery cells, the conductive wire, which is a copper wire or a copper wire partially wrapped with a composite film, is partially cut, an intersection point where each cut conductive wire intersects with the positive electrode fine grid line is included in an insulating region for insulatingly connecting the cut conductive wire and the positive electrode fine grid line, an intersection point where each cut conductive wire intersects with the negative electrode fine grid line is included in a conductive region for electrically connecting the cut conductive wire and the negative electrode fine grid line, an intersection point where each uncut conductive wire intersects with the positive electrode fine grid line is included in a conductive region for electrically connecting the uncut conductive wire and the positive electrode fine grid line, an intersection point where each uncut conductive wire intersects with the negative electrode fine grid line is included in an insulating region for insulatingly connecting the uncut conductive wire and the negative electrode fine grid line, the positive electrode fine grid line includes a plurality of line segments of aluminum grid lines and a plurality of line segments of silver grid lines alternately provided, each line segment of the silver grid line is electrically connected by welding to a plurality of the conductive wires that are continuously arranged and uncut in the conductive region, each line segment of the aluminum grid line is insulatingly connected to a plurality of the conductive wires that are continuously arranged and cut in the insulating region, characterized in that it is a back contact solar cell string.

2. the conductive wire includes a first conductive wire and a second conductive wire, the first conductive wire is electrically connected to the positive electrode fine grid line on the battery cell and the negative electrode fine grid line on the adjacent battery cell in the conductive region, and the first conductive wire is insulatingly connected to the negative electrode fine grid line on the battery cell and the positive electrode fine grid line on the adjacent battery cell in the insulating region, The second conductive wire is electrically connected to the negative electrode fine grid line on the battery cell and the positive electrode fine grid line on the adjacent battery cell in the conductive region, and the second conductive wire is insulated from the positive electrode fine grid line on the battery cell and the negative electrode fine grid line on the adjacent battery cell in the insulating region. The back-contact solar cell string according to claim 1, characterized in that it is connected.

3. The composite film is a POE film, an EVA film, a PVB film, or a co-extruded film composed of a POE and an EVA film. The back-contact solar cell string according to claim 1, characterized in that it is such.

4. The back-contact solar cell string according to claim 1, characterized in that an insulator is provided in the insulating region.

5. The back-contact solar cell string according to claim 2, characterized in that the same number of the second conductive wires corresponding to at least two of the first conductive wires are provided alternately.

6. The first conductive wire and the second conductive wire are provided alternately, or two first conductive wires and two second conductive wires are provided alternately. The back-contact solar cell string according to claim 5, characterized in that it is such.

7. The back-contact solar cell string according to claim 1, characterized in that the same number of conductive wires are cut every first predetermined number of conductive wires between two adjacent battery cells.

8. The back-contact solar cell string according to claim 7, characterized in that the first predetermined number is 2 to 4.

9. The back-contact solar cell string according to claim 1, further comprising a conductive bus bar located at an end of the solar cell string, and the same number of conductive wires are electrically connected to the conductive bus bar every second predetermined number of conductive wires.

10. The back-contact solar cell string according to claim 9, characterized in that the second predetermined number is 1 to 4.

11. A battery assembly, characterized in that it includes the back-contact solar cell string according to any one of claims 1 to 10.

12. A solar power generation system, characterized in that it includes the battery assembly according to claim 11.

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