Solar cell module, solar cell string and photovoltaic module

Abstract

The utility model relates to the technical field of solar cells, in particular to a solar cell module, a solar cell string and a photovoltaic module. The solar cell module comprises a back contact solar cell and a plurality of grid line bus bars. The back contact solar cell comprises a silicon substrate, a plurality of current collection grid lines and a plurality of bus grid lines, the positive current collection grid lines and the negative current collection grid lines are alternately arranged on the back face of the silicon substrate in the first direction, all the current collection grid lines extend in the second direction, and in the second direction, the first current collection grid lines and the second current collection grid lines extend in the first direction. The positive-polarity bus grid line and the negative-polarity bus grid line are respectively arranged on two opposite sides of the back surface of the silicon substrate, and each bus grid line is connected with the tail end of the current collection grid line with the same polarity and is separated from the tail end of the current collection grid line with the opposite polarity. And in the second direction, each grid line bus bar is electrically connected with the current collection grid line with the same polarity and is insulated from the current collection grid line with the opposite polarity. The solar cell module has a good current collection effect, and the grid breaking phenomenon is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a solar cell module, a solar cell string and a photovoltaic module. BACKGROUND

[0002] In order to obtain a better current collection effect, the grid lines of the back contact solar cell tend to be as long as possible. However, the grid lines are difficult to be lengthened due to the layout mode of the grid lines. Even if the layout mode of the grid lines is adjusted, the grid lines can be lengthened but the grid break phenomenon is prone to occur, which causes the problem of missing conduction and further affects the overall efficiency of the solar cell string. SUMMARY

[0003] The embodiments of the present application disclose a solar cell module, a solar cell string and a photovoltaic module, which can have a better current collection effect and reduce the grid break phenomenon.

[0004] In order to achieve the above-mentioned purpose, in a first aspect, the embodiments of the present application disclose a solar cell module, comprising:

[0005] A plurality of back contact solar cells, comprising a silicon substrate, a plurality of current collection grid lines and a plurality of bus grid lines, a part of the current collection grid lines are positive and another part of the current collection grid lines are negative, the current collection grid lines with positive polarity and the current collection grid lines with negative polarity are alternately arranged on the back surface of the silicon substrate and the direction of alternately arranged is a first direction, each of the current collection grid lines extends along a second direction, and the second direction intersects the first direction; at least one of the bus grid lines is positive and at least one of the bus grid lines is negative, in the second direction, the bus grid lines with positive polarity and the bus grid lines with negative polarity are arranged on two opposite sides of the back surface of the silicon substrate respectively, each of the bus grid lines is connected to the end of the current collection grid line with the same polarity and is separated from the end of the current collection grid line with opposite polarity; and

[0006] A plurality of grid line bus bars, at least one of the grid line bus bars is positive and at least one of the grid line bus bars is negative; in the second direction, each of the grid line bus bars is arranged between the two ends of the current collection grid line and intersects the plurality of current collection grid lines, each of the grid line bus bars is electrically connected to the current collection grid line with the same polarity and is insulated from the current collection grid line with opposite polarity.

[0007] In a possible implementation manner of the first aspect, the back contact solar cell further comprises a doped layer of two conductive types, the two conductive types are P type and N type respectively, the current collection grid lines with two polarities are in ohmic contact with the doped layer of two conductive types respectively, and the bus grid lines with two polarities are arranged on the doped layer of the corresponding conductive type.

[0008] In a possible implementation manner of the first aspect, the doping layers of the two conductive types respectively include first doping sub-layers and second doping sub-layers;

[0009] The first doping sub-layers of the P type and the first doping sub-layers of the N type are alternately arranged on the back surface of the silicon substrate along the first direction, each of the first doping sub-layers extends along the second direction, and the collector grid lines of the two polarities are in ohmic contact with the first doping sub-layers of the corresponding conductive type respectively;

[0010] In the second direction, the second doping sub-layers of the P type and the first doping sub-layers of the N type are respectively arranged on two opposite sides of the back surface of the silicon substrate, each of the second doping sub-layers is connected to the ends of the first doping sub-layers of the same conductive type and is separated from the ends of the first doping sub-layers of the opposite conductive type, and the bus grid lines of the two polarities are respectively arranged on the second doping sub-layers of the corresponding conductive type.

[0011] In a possible implementation manner of the first aspect, the back contact solar cell further includes an isolation film layer;

[0012] The isolation film layer is arranged between two adjacent first doping sub-layers;

[0013] And / or, the isolation film layer is arranged between the first doping sub-layers of the opposite conductive type and the second doping sub-layers.

[0014] In a possible implementation manner of the first aspect, an insulating adhesive layer is arranged between each of the grid bus bars and the collector grid lines of the opposite polarity;

[0015] And / or, a plurality of collector grid lines of the same polarity are arranged in an array along the first direction, and the collector grid lines of different polarities are staggered in the second direction, so that the bus grid lines are separated from the ends of a plurality of collector grid lines of the opposite polarity.

[0016] In a possible implementation manner of the first aspect, in the second direction, the size of the silicon substrate is W, the length of each of the collector grid lines is L, and W:L=1:(0.9-0.99);

[0017] And / or, the line width of the collector grid line is 0.1 μm-10 μm;

[0018] And / or, the number of the collector grid lines on each of the back contact solar cells is 10-2000;

[0019] And / or, in the first direction, the pitch between two adjacent collector grid lines is 0.1 mm-5 mm;

[0020] And / or, the first direction is perpendicular to the second direction.

[0021] And / or, the cross-sectional shape of the gate line bus bar is circular, triangular, trapezoidal or rectangular;

[0022] And / or, the gate line bus bar is a tin-plated copper strip or a conductive composite material strip;

[0023] And / or, the cross-sectional area of the gate line bus bar is 0.001mm 2 ~2mm 2 .

[0024] In a second aspect, the embodiments of the present application disclose a solar cell string, which comprises:

[0025] The solar cell module as described in the first aspect; and

[0026] A plurality of series conductive members, which are in series with the solar cell module.

[0027] In a possible implementation manner of the second aspect, the series conductive member is an inter-sheet bus bar, the number of the back contact solar cells is multiple, the multiple back contact solar cells are arranged in the second direction, at least one inter-sheet bus bar is arranged between two adjacent back contact solar cells, and the inter-sheet bus bar is electrically connected to the current collecting grid lines on the two back contact solar cells to connect the two back contact solar cells in series.

[0028] In a possible implementation manner of the second aspect, one end of the plurality of current collecting grid lines connected to the bus bar is provided with a welding portion, the plurality of welding portions located on the same side of the silicon substrate are arranged at intervals in the first direction, the inter-sheet bus bar extends along the first direction, and the inter-sheet bus bar is welded to the plurality of welding portions to electrically connect the current collecting grid lines.

[0029] In a possible implementation manner of the second aspect, the inter-sheet bus bar comprises a main body segment and a plurality of protruding segments, the main body segment extends along the first direction, in the second direction, the plurality of protruding segments are arranged on both sides of the main body segment respectively, the plurality of protruding segments located on the same side of the main body segment are arranged at intervals along the first direction, and each protruding segment is welded to each welding portion to electrically connect the current collecting grid lines;

[0030] Or, the shape of the inter-sheet bus bar is rectangular, and in the second direction, two side edges of the inter-sheet bus bar are welded to the plurality of welding portions to electrically connect the current collecting grid lines;

[0031] And / or, the cross-sectional area of the inter-sheet bus bar is 0.001mm 2 ~5mm 2 ;

[0032] and / or, the welding part has a shape of a circle, a triangle, a rectangle, a pentagon, a hexagon or a trapezoid.

[0033] In a possible implementation of the second aspect, the series conductive piece is a solder strip, the number of the back contact solar cells is multiple, the multiple back contact solar cells are arranged in the second direction, each of the solder strips extends along the second direction and is stacked with the current collecting grid lines, each of the current collecting grid lines is provided with a welding part at one end connected with the bus grid line, each of the solder strips is welded with the welding parts on two of the back contact solar cells to connect the two back contact solar cells in series, and the grid line bus is arranged on a side of the solder strip away from the back contact solar cells, and an insulating adhesive layer is arranged between each of the grid line buses and the solder strip on the current collecting grid line with opposite polarity.

[0034] In a third aspect, the embodiments of the present application disclose a photovoltaic module, which comprises the solar cell module according to the first aspect or the solar cell string according to the second aspect.

[0035] Compared with the prior art, the beneficial effects of the present application are that the back contact solar cells of the solar cell string have a better current collection effect by improving the grid line layout. Specifically, the positive polarity current collecting grid lines and the negative polarity current collecting grid lines are alternately arranged on the back surface of the silicon substrate and the direction of alternately arranging is the first direction, and each of the current collecting grid lines extends along the second direction. At the same time, in the second direction, the positive polarity bus grid lines and the negative polarity bus grid lines are arranged on the two opposite sides of the back surface of the silicon substrate, respectively. By such layout of the current collecting grid lines and the bus grid lines, each of the bus grid lines is connected to the end of the current collecting grid line with the same polarity and is separated from the end of the current collecting grid line with opposite polarity. The current collecting grid line can be extended along the second direction to approach the two opposite sides of the back surface of the silicon substrate as much as possible, and the length of the current collecting grid line can be longer, thereby obtaining a better current collection effect.

[0036] In the case of a longer current collecting grid line, in order to reduce the grid breakage phenomenon, the bus grid line of the back contact solar cell interconnects multiple current collecting grid lines with the same polarity at the end of the current collecting grid line. In addition, the solar cell string is also provided with a grid line bus, and in the second direction, each of the grid line buses is arranged between the two ends of the current collecting grid line, and each of the grid line buses is electrically connected to the multiple current collecting grid lines with the same polarity and is insulated from the current collecting grid line with opposite polarity. It can be understood that the grid line bus interconnects multiple current collecting grid lines with the same polarity between the two ends of the current collecting grid line. The solar cell string interconnects the current collecting grid line at multiple positions of the current collecting grid line by the grid line bus and the bus grid line to reduce the grid breakage phenomenon.

[0037] In summary, the current collecting grid line of the solar cell string has a better current collection effect and the grid breakage phenomenon is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of a solar cell module disclosed in the first aspect of this application;

[0040] Figure 2 for Figure 1 A magnified view of a portion of region A shown in the image;

[0041] Figure 3 for Figure 1 A magnified view of region B shown in the image;

[0042] Figure 4 This is a schematic diagram of the back-contact solar cell disclosed in the first aspect of this application;

[0043] Figure 5 for Figure 4 A magnified view of a portion of region C shown in the diagram;

[0044] Figure 6 for Figure 4 A magnified view of region D shown in the image;

[0045] Figure 7 This is another structural schematic diagram of a solar cell module disclosed in the first aspect of this application;

[0046] Figure 8 This is a schematic diagram of the structure of a solar cell string (with inter-cell busbars as the series conductive components) disclosed in the second aspect of this application;

[0047] Figure 9 for Figure 8 A magnified view of region E shown in the image;

[0048] Figure 10 This is another structural schematic diagram of a solar cell string (with inter-cell busbars as the series conductive components) disclosed in the second aspect of this application;

[0049] Figure 11 for Figure 10 A magnified view of region F shown in the diagram;

[0050] Figure 12 This is a schematic diagram of the structure of a solar cell string (with solder strips as the series conductive components) disclosed in the second aspect of this application;

[0051] Figure 13 forFigure 12 a close-up view of the G region shown in FIG. 1 1 ;

[0052] Figure 14 for Figure 12 another close-up view of the G region shown in FIG. 1 1 ;

[0053] Figure 15 for Figure 14 A-A sectional view shown in FIG. 1 1.

[0054] BRIEF DESCRIPTION OF DRAWINGS

[0055] 1. solar cell string; 10. solar cell module; 1 1. back contact solar cell; 12. silicon substrate; 13a and 13b. collector grid lines; 14a and 14b. busbar grid lines; 15a and 15b. doped layers; 151 a and 151 b. first doped sub-layers; 152a and 152b. second doped sub-layers; 16. isolation film layer; 17. insulating adhesive layer; 18. soldering part; 19a and 19b. grid busbar; 20. inter-tab busbar; 21. main body section; 22. protruding section; 30. solder strip; X. first direction; Y. second direction. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0057] In the present application, the terms "set", "provided with", "connected", and "linked" should be interpreted broadly. For example, it can be fixed connection, detachable connection, or integral configuration; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] In addition, the terms "first", "second", and the like are mainly used to distinguish different devices, elements or components (the specific types and configurations can be the same or different), and are not intended to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise stated, the meaning of "multiple" is two or more.

[0059] The technical solutions of the present application will be described below with reference to the embodiments and drawings.

[0060] In the first aspect, please refer to Figures 1 to 3As shown, the embodiment of the present application discloses a solar cell module 10, comprising a plurality of back contact solar cells 11 and a plurality of grid bus bars 19a and 19b.

[0061] The back contact solar cell 11 comprises a silicon substrate 12, a plurality of current collecting grid lines 13a and 13b and a plurality of bus grid lines 14a and 14b, a part of the current collecting grid lines 13a are positive polarity and another part of the current collecting grid lines 13b are negative polarity, the positive polarity current collecting grid lines 13a and the negative polarity current collecting grid lines 13b are alternately arranged on the back surface of the silicon substrate 12 and the direction of the alternately arranged is the first direction X, each of the current collecting grid lines 13a and 13b extends along the second direction Y, and the second direction Y intersects the first direction X. At least one of the bus grid lines 14a is positive polarity and at least one of the bus grid lines 14b is negative polarity, in the second direction Y, the positive polarity bus grid lines 14a and the negative polarity bus grid lines 14b are respectively arranged on the two opposite sides of the back surface of the silicon substrate 12. Each of the bus grid lines is connected to the end of the current collecting grid line with the same polarity and is separated from the end of the current collecting grid line with the opposite polarity. In more detail, referring to Figure 2 , the positive polarity bus grid line 14a is connected to the end of the positive polarity current collecting grid line 13a and is separated from the end of the negative polarity current collecting grid line 13b. Referring to Figure 3 , the negative polarity bus grid line 14b is connected to the end of the negative polarity current collecting grid line 13b and is separated from the end of the positive polarity current collecting grid line 13a.

[0062] At least one of the grid bus bars 19a is positive polarity and at least one of the grid bus bars 19b is negative polarity. In the second direction Y, each of the grid bus bars 19a and 19b is arranged between the two ends of the current collecting grid lines 13a and 13b and intersects the plurality of current collecting grid lines 13a and 13b. Each of the grid bus bars is electrically connected to the current collecting grid line with the same polarity and is insulated from the current collecting grid line with the opposite polarity. In more detail, referring to Figure 2 , the negative polarity grid bus bar 19b is electrically connected to the negative polarity current collecting grid line 13b and is insulated from the positive polarity current collecting grid line 13a. Referring to Figure 3 , the positive polarity grid bus bar 19a is electrically connected to the positive polarity current collecting grid line 13a and is insulated from the negative polarity current collecting grid line 13b.

[0063] In the embodiment of the present application, the back contact solar cell 11 of the solar cell string 1 obtains a better current collection effect by improving the layout of the grid lines. Specifically, the positive polarity current collecting grid lines 13a and the negative polarity current collecting grid lines 13b are alternately arranged on the back surface of the silicon substrate 12 and the direction of the alternately arranged is the first direction X, and each of the current collecting grid lines 13a and 13b extends along the second direction Y. Optionally, the first direction X is perpendicular to the second direction Y. Meanwhile, along the second direction Y, the positive polarity busbar 14a and the negative polarity busbar 14b are arranged on the back surface of the silicon substrate 12 at two opposite sides respectively. Each busbar is connected to the end of the current collecting grid line with the same polarity and is separated from the end of the current collecting grid line with the opposite polarity. In more detail, the positive polarity busbar 14a is connected to the end of the positive polarity current collecting grid line 13a and is separated from the end of the negative polarity current collecting grid line 13b, and the negative polarity busbar 14b is connected to the end of the negative polarity current collecting grid line 13b and is separated from the end of the positive polarity current collecting grid line 13b.

[0064] By such layout of the current collecting grid lines 13a and 13b and the busbars 14a and 14b, the current collecting grid lines 13a and 13b can be extended along the second direction Y to approach the two opposite sides of the back surface of the silicon substrate 12 as much as possible, the length of the current collecting grid lines 13a and 13b can be longer, and thus a better current collection effect is obtained.

[0065] In the case of longer current collecting grid lines 13a and 13b, in order to reduce the grid breakage phenomenon, the busbars 14a and 14b of the back contact solar cell 11 interconnect a plurality of current collecting grid lines 13a and 13b with the same polarity at the ends of the current collecting grid lines 13a and 13b. In addition, the solar cell string 1 is also provided with grid busbars 19a and 19b, and along the second direction Y, each of the grid busbars 19a and 19b is arranged between the two ends of the current collecting grid lines 13a and 13b, and each of the grid busbars is configured to be electrically connected to a plurality of current collecting grid lines with the same polarity and insulated from the current collecting grid lines with the opposite polarity. It can be understood that the grid busbars 19a and 19b respectively interconnect a plurality of current collecting grid lines 13a and 13b with the same polarity between the two ends of the current collecting grid lines 13a and 13b. The solar cell string 1 interconnects the current collecting grid lines 13a and 13b at a plurality of positions of the current collecting grid lines 13a and 13b by the grid busbars 19a and 19b and the busbars 14a and 14b respectively, so as to reduce the grid breakage phenomenon.

[0066] In summary, the current collecting grid lines 13a and 13b of the solar cell string 1 have a better current collection effect and the grid breakage phenomenon is reduced.

[0067] In some embodiments, with reference to Figure 2 and Figure 3The insulating glue layer 17 is arranged between the grid line bus bar 19a and 19b and the collector grid line 13a and 13b with opposite polarity, and the insulating glue layer 17 is arranged between the grid line bus bar 19a and 19b and the collector grid line 13a and 13b with opposite polarity to insulate the grid line bus bar 19a and 19b and the collector grid line 13a and 13b with opposite polarity and reduce the short circuit phenomenon.

[0068] The insulating glue layer 17 arranged between the grid line bus bar 19a and 19b and the collector grid line 13a and 13b with opposite polarity can be interpreted as: the insulating glue layer 17 can be arranged on the grid line bus bar 19a and 19b and / or the collector grid line 13a and 13b, and preferably the insulating glue layer 17 is arranged on the collector grid line 13a and 13b. More preferably, the insulating glue layer 17 is arranged on each of the collector grid line 13a and 13b, and the insulating glue layer 17 on the collector grid line 13a and 13b with the same polarity is arranged on the same straight line to insulate and isolate the grid line bus bar 19a and 19b extending in a straight line.

[0069] In some embodiments, referring to Figure 2 and Figure 3 , the plurality of collector grid lines 13a and 13b with the same polarity are arranged in the first direction X, and the collector grid lines 13a and 13b with different polarities are arranged in the second direction Y to separate the bus grid line 14a and 14b from the ends of the plurality of collector grid lines 13a and 13b with opposite polarity, thereby reducing the short circuit phenomenon between the bus grid line 14a and 14b and the collector grid line 13a and 13b with opposite polarity.

[0070] In some embodiments, referring to Figures 4 to 6 , the back contact solar cell 11 further comprises a doped layer 15a and 15b of two conductive types, which are P-type and N-type respectively, and the collector grid line 13a and 13b of two polarities are in ohmic contact with the doped layer 15a and 15b of two conductive types respectively to transmit current to the doped layer 15a and 15b of two conductive types respectively. See Figure 5 and Figure 6 , the collector grid line 13a with positive polarity is in ohmic contact with the doped layer 15a of P-type, and the collector grid line 13b with negative polarity is in ohmic contact with the doped layer 15b of N-type.

[0071] Further, the bus grid line 14a and 14b of two polarities is arranged on the doped layer 15a and 15b of corresponding conductive type respectively. See Figure 5 and Figure 6The positive bus grid lines 14a are disposed on the P-type doped layer 15a, and the negative bus grid lines 14b are disposed on the N-type doped layer 15b. It should be noted that the bus grid lines 14a and 14b being disposed on the doped layers 15a and 15b of the corresponding conductivity type does not mean that the bus grid lines 14a and 14b are in direct contact with the doped layers 15a and 15b of the corresponding conductivity type. There can be other film layers, such as passivation layers or anti-reflective layers, between the bus grid lines 14a and 14b and the doped layers 15a and 15b of the corresponding conductivity type. Of course, the bus grid lines 14a and 14b can also be in direct contact with the doped layers 15a and 15b of the corresponding conductivity type.

[0072] As an example, the doped layers 15a and 15b can be doped polysilicon layers, and the two conductivity types of the doped layers 15a and 15b are N-type doped polysilicon layers and P-type doped polysilicon layers. Alternatively, when the doped layers 15a and 15b are doped polysilicon layers, a dielectric layer, such as a silicon oxide dielectric layer, can be disposed between the doped polysilicon layers and the silicon substrate 12. As another example, the doped layers 15a and 15b can be diffusion layers, and the two conductivity types of the doped layers 15a and 15b can be boron diffusion layers and phosphorus diffusion layers.

[0073] Further, the two conductivity type doped layers 15a and 15b each include a first doped sub-layer 151a and 151b and a second doped sub-layer 152a and 152b.

[0074] The P-type first doped sub-layers 151a and the N-type first doped sub-layers 151b are alternately disposed on the back surface of the silicon substrate 12 along the first direction X, each of the first doped sub-layers 151a and 151b extends along the second direction Y, and the collector grid lines 13a and 13b of the two polarities are in ohmic contact with the first doped sub-layers 151a and 151b of the corresponding conductivity type, respectively. See Figure 5 and Figure 6 The positive collector grid lines 13a are in ohmic contact with the P-type first doped sub-layers 151a, and the negative collector grid lines 13b are in ohmic contact with the N-type first doped sub-layers 151b.

[0075] In the second direction Y, the P-type second doped sub-layers 152a and the N-type first doped sub-layers 151b are disposed on the back surface of the silicon substrate 12 on two opposite sides, respectively, each of the second doped sub-layers 152a and 152b is connected to the ends of the first doped sub-layers 151a and 151b of the same conductivity type and is separated from the ends of the first doped sub-layers 151a and 151b of the opposite conductivity type, and the bus grid lines 14a and 14b of the two polarities are disposed on the second doped sub-layers 152a and 152b of the corresponding conductivity type, respectively. See Figure 5 and Figure 6The positive bus grid lines 14a are arranged on the P-type second sub-doped layer 152a, and the negative bus grid lines 14b are arranged on the N-type second sub-doped layer 152b.

[0076] The back contact solar cell 11 is optimized in the pattern of the two conductive type doped layers 15a and 15b, and the current collecting grid lines 13a and 13b and the first sub-doped layers 151a and 151b all extend along the second direction Y to the two opposite sides of the back surface of the silicon substrate 12 as close as possible, thereby increasing the current collecting capacity of the current collecting grid lines 13a and 13b.

[0077] Referring back to Figures 4 to 6 Optionally, the back contact solar cell 11 further comprises an isolation film layer 16. The isolation film layer 16 is arranged between two adjacent first sub-doped layers 151a and 151b; and / or, the isolation film layer 16 is arranged between the first sub-doped layers 151a and 151b and the second sub-doped layers 152a and 152b of opposite conductive types.

[0078] The isolation film layer 16 is used to isolate the two first sub-doped layers 151a and 151b of opposite conductive types. And / or, the isolation film layer 16 is used to isolate the first sub-doped layers 151a and 151b and the second sub-doped layers 152a and 152b of opposite conductive types, for example, the isolation film layer 16 is arranged between the P-type first sub-doped layer 151a and the N-type second sub-doped layer 152b, and for another example, the isolation film layer 16 is arranged between the N-type first sub-doped layer 151b and the P-type second sub-doped layer 152a. Exemplarily, the material of the isolation film layer 16 is silicon oxide. Of course, the material of the isolation film layer 16 can also be other insulating materials, and the embodiments of the present application do not limit this.

[0079] The current collecting grid lines will be described in detail below.

[0080] Referring back to Figure 2 In the first direction X, if the distance D between the two adjacent current collecting grid lines 13a and 13b is less than 0.1 mm, the light shielding loss of the current collecting grid lines 13a and 13b will be large due to the dense distribution of the current collecting grid lines 13a and 13b, and if the distance D between the two adjacent current collecting grid lines 13a and 13b is greater than 5 mm, the current collecting effect of the current collecting grid lines 13a and 13b will be poor due to the sparse distribution of the current collecting grid lines 13a and 13b. Preferably, in the first direction X, the distance D between the two adjacent current collecting grid lines 13a and 13b is 0.1 mm to 5 mm, including any point value within the range of the distance D, for example, 0.1 mm, 2.5 mm or 5 mm, and the light shielding loss is less and the current collecting effect is better.

[0081] Preferably, referring back to Figure 7In the second direction Y, the size of the silicon substrate 12 is W, the length of each of the collector grid lines 13a and 13b is L, and W:L = 1:(0.9-0.99), for example, W:L = 1:0.9, W:L = 1:0.95, or W:L = 1:0.99. It can be understood that the length of the collector grid lines 13a and 13b of the present application can be as long as possible. In the second direction Y, the length of the collector grid lines 13a and 13b tends to be consistent with the size of the silicon substrate 12, and the longer collector grid lines 13a and 13b have better current collection effect.

[0082] It should be noted that the line width of the collector grid lines 13a and 13b refers to the size thereof in the first direction X. If the line width of the collector grid lines 13a and 13b is less than 0.1 μm, the cross-sectional area of the collector grid lines 13a and 13b is small, and the resistance thereof is large. If the line width of the collector grid lines 13a and 13b is greater than 10 μm, the light-shielding area of the collector grid lines 13a and 13b is increased, and the light absorption of the back contact solar cell 11 is affected. Preferably, the line width of the collector grid lines 13a and 13b is 0.1 μm-10 μm, including any point value within the range, for example, 0.1 μm, 5 μm, or 10 μm, having a small resistance and a small light-shielding loss.

[0083] If the number of the collector grid lines 13a and 13b on each back contact solar cell 11 is less than 10, the distribution of the collector grid lines 13a and 13b is sparse, and it is difficult to perform good current transmission on the back contact solar cell 11. If the number of the collector grid lines 13a and 13b on each back contact solar cell 11 is greater than 2000, the total light-shielding area of all the collector grid lines 13a and 13b is large. Preferably, the number of the collector grid lines 13a and 13b on each back contact solar cell 11 is 10-2000, having good current transmission effect and small light-shielding loss.

[0084] The grid bus bar will be described in detail below.

[0085] Optionally, the cross-sectional shape of the grid bus bar is circular, triangular, trapezoidal, or rectangular. These cross-sectional shapes of the grid bus bar can reflect a part of the light to the back contact solar cell.

[0086] Optionally, the grid bus bar is a tin-plated copper strip or a conductive composite material strip, and the conductive composite material is, for example, a metal composite material, such as a silver-containing composite material, a copper-containing composite material, or an aluminum-containing composite material. The tin-plated copper strip and the conductive composite material strip have composite properties, for example, in the tin-plated copper strip, the copper portion has good electrical conductivity, and the tin portion has good corrosion resistance. In other words, the tin-plated copper strip has good composite properties of electrical conductivity and corrosion resistance.

[0087] If the cross-sectional area of the grid bus bar is less than 0.001 mm2 The grid line bus bar has high electrical loss. If the cross-sectional area of the grid line bus bar is greater than 2mm 2 , the size of the grid line bus bar is large, and the light shielding area of the grid line bus bar is large. Preferably, the cross-sectional area of the grid line bus bar is 0.001mm 2 ~ 2mm 2 including any point value in the range, for example, 0.001mm 2 , 1mm 2 or 2mm 2 , has low resistance and electrical loss, and less light shielding loss.

[0088] In a second aspect, with reference to Figure 8 , Figure 10 and Figure 12 , the embodiment of the present application discloses a solar cell string 1, comprising the solar cell assembly 10 as described in the first aspect and a plurality of series conductive members, the series conductive members are connected in series with the solar cell assembly 10. The solar cell assembly 10 of the solar cell string 1 has good current collection effect, and the grid break phenomenon is reduced, which is beneficial to improve the reliability and efficiency of the solar cell string 1.

[0089] In some embodiments, with reference to Figures 8 to 11 , the series conductive member is an inter-sheet bus bar 20, the number of the back contact solar cells 11 is a plurality, the plurality of back contact solar cells 11 are arranged in the second direction Y, and at least one inter-sheet bus bar 20 is arranged between the two adjacent back contact solar cells 11. The inter-sheet bus bar 20 is electrically connected to the current collecting grid lines 13a and 13b on the two back contact solar cells 11 to connect the two back contact solar cells 11 in series.

[0090] In the embodiment of the present application, since the bus grid lines 14a and 14b are arranged on the side edges of the back contact solar cells 11 in the second direction Y, and the plurality of back contact solar cells 11 are arranged in the second direction Y, the series connection can be realized by the inter-sheet bus bar 20 arranged between the two adjacent back contact solar cells 11. In the related art, the back contact solar cells 11 are connected in series by the plurality of solder strips 30 transversely arranged on the surface of the back contact solar cells 11. Compared with the related art, the present application only needs one inter-sheet bus bar 20 to realize the series connection, and the light shielding area is smaller and the soldering is more convenient.

[0091] It should be noted that the number of back contact solar cells can be two, three or four, etc. The specification of the back contact solar cell in the present application can be a whole cell or a cut cell, for example, a half cell, a third cell or a fourth cell, and the present application does not limit the specification.

[0092] Further, the plurality of current collecting grid lines 13a and 13b are provided with soldering portions 18 at the ends connected to the bus grid lines 14a and 14b, the plurality of soldering portions 18 are arranged at intervals in the first direction X on the same side of the silicon substrate 12, the inter-tab bus bar 20 extends in the first direction X, and the inter-tab bus bar 20 is soldered to the plurality of soldering portions 18 to electrically connect the current collecting grid lines 13a and 13b. The soldering portions 18 are, for example, solder pads. It can be understood that the soldering portions 18 are arranged at the ends of the current collecting grid lines 13a and 13b connected to the bus grid lines 14a and 14b to reduce the warping of the back contact solar cell 11 after soldering and to increase the soldering tensile force of the edges.

[0093] Optionally, referring to Figure 8 and Figure 9 , the inter-tab bus bar 20 includes a main segment 21 and a plurality of protruding segments 22, the main segment 21 extends in the first direction X, the plurality of protruding segments 22 are arranged at both sides of the main segment 21 in the second direction Y, and the plurality of protruding segments 22 on the same side of the main segment 21 are arranged at intervals in the first direction X. Each of the protruding segments 22 is soldered to each of the soldering portions 18 to electrically connect the current collecting grid lines 13a and 13b.

[0094] The inter-tab bus bar 20 is soldered to the soldering portions 18 through the protruding segments 22, and the width of the main segment 21 can be narrowed, where the width refers to the size of the main segment 21 in the second direction Y. In this way, on the same side of the inter-tab bus bar 20, after the protruding segments 22 are electrically connected to the current collecting grid lines 13a and 13b of one polarity, the narrowed main segment 21 is beneficial to the main segment 21 being as far away as possible from the current collecting grid lines 13a and 13b of the other polarity. On the other hand, the narrowed main segment 21 also reduces the light blocking area of the inter-tab bus bar 20 to some extent, which is beneficial to improving the bifaciality of the back contact solar cell 11.

[0095] Optionally, referring to Figure 10 and Figure 11 , the inter-tab bus bar 20 has a rectangular shape, and the two sides of the inter-tab bus bar 20 in the second direction Y are soldered to the plurality of soldering portions 18 to electrically connect the current collecting grid lines 13a and 13b.

[0096] The inter-tab bus bar 20 having a rectangular shape can be soldered to the plurality of soldering portions 18 on the current collecting grid lines 13a and 13b, which reduces the alignment requirement of the inter-tab bus bar 20 and the soldering portions 18.

[0097] If the cross-sectional area of the inter-tab bus bar 20 is less than 0.001 mm 2 , the electrical loss of the inter-tab bus bar 20 is high. If the cross-sectional area of the inter-tab bus bar 20 is greater than 5 mm 2, the cross-sectional area of the inter-tab busbar 20 is preferably 0.001mm 2 ~5mm 2 including any value within the range of the cross-sectional area, such as 0.001mm 2 , 2mm 2 or 5mm 2 , has lower resistance and power loss, and less shading loss.

[0098] For example, referring to Figure 11 , the welding portion 18 has a circular shape. As other examples, the welding portion can also have a triangular, rectangular, pentagonal, hexagonal or trapezoidal shape. The welding portion 18 with these shapes has better welding effect.

[0099] In some embodiments, referring to Figures 12 to 15 , the series conductive member is a solder strip 30, and the number of the back contact solar cells 11 is multiple, and the multiple back contact solar cells 11 are arranged in the second direction Y. Each solder strip 30 extends along the second direction Y and is stacked with the current collecting grid lines 13a and 13b, and each solder strip 30 is welded with the welding portions 18 on two back contact solar cells 11 to series connect the two back contact solar cells 11.

[0100] In the present embodiment, the back contact solar cells 11 can also be series connected by the solder strip 30. Specifically, the solder strip 30 is welded and fixed with the welding portions 18 at the ends of the current collecting grid lines 13a and 13b, which can increase the welding tension of the solder strip 30 and improve the welding reliability.

[0101] Further, the present application considers that the grid busbar can contact the solder strip on the current collecting grid line with opposite polarity, and based on this, in the present embodiment, the grid busbar is arranged on the side of the solder strip away from the back contact solar cell, and an insulating adhesive layer is arranged between each grid busbar and the solder strip on the current collecting grid line with opposite polarity. Referring to the figure, taking the current collecting grid line 13a with positive polarity as an example, the insulating adhesive layer 17 can be arranged on the stacked structure of the current collecting grid line 13a and the solder strip 30, or the insulating adhesive layer 17 can be arranged on the grid busbar 19b. The insulating adhesive layer 17 isolates the grid busbar 19b from the solder strip 30 on the current collecting grid line 13a with opposite polarity, reduces the short circuit phenomenon, and further enables the solar cell module to be compatible with the solder strip 30 welding process.

[0102] In a third aspect, the present application discloses a photovoltaic module, which comprises the solar cell module according to the first aspect or the solar cell string according to the second aspect.

[0103] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solar cell module, characterized by, The back contact solar cell comprises: a plurality of back contact solar cells, including a silicon substrate, a plurality of collecting grid lines and a plurality of bus grid lines, a part of the collecting grid lines are positive and another part of the collecting grid lines are negative, the positive collecting grid lines and the negative collecting grid lines are alternately arranged on the back surface of the silicon substrate and the direction of alternately arranging is the first direction, each of the collecting grid lines extends along the second direction, and the second direction intersects with the first direction; at least one of the bus grid lines is positive and at least one of the bus grid lines is negative, in the second direction, the positive bus grid lines and the negative bus grid lines are respectively arranged on two opposite sides of the back surface of the silicon substrate, each of the bus grid lines is connected to the end of the collecting grid line with the same polarity and is separated from the end of the collecting grid line with the opposite polarity; and a plurality of grid bus bars, at least one of the grid bus bars is positive and at least one of the grid bus bars is negative, in the second direction, each of the grid bus bars is arranged between the two ends of the collecting grid line and intersects with a plurality of the collecting grid lines, each of the grid bus bars is electrically connected to the collecting grid line with the same polarity and is insulated from the collecting grid line with the opposite polarity.

2. The solar cell module according to claim 1, characterized by The back contact solar cell further comprises two kinds of doped layers of conductive types, the two kinds of conductive types are P type and N type respectively, the collecting grid lines of the two polarities are respectively in ohmic contact with the doped layers of the two kinds of conductive types, and the bus grid lines of the two polarities are respectively arranged on the doped layers of the corresponding conductive types.

3. The solar cell module according to claim 2, characterized by The doped layers of the two kinds of conductive types respectively comprise first doped sub-layers and second doped sub-layers; The first doped sub-layers of the P type and the first doped sub-layers of the N type are alternately arranged on the back surface of the silicon substrate along the first direction, each of the first doped sub-layers extends along the second direction, and the collecting grid lines of the two polarities are respectively in ohmic contact with the first doped sub-layers of the corresponding conductive types; In the second direction, the second doped sub-layers of the P type and the first doped sub-layers of the N type are respectively arranged on two opposite sides of the back surface of the silicon substrate, each of the second doped sub-layers is connected to the end of the plurality of first doped sub-layers of the same conductive type and is separated from the end of the plurality of first doped sub-layers of the opposite conductive type, and the bus grid lines of the two polarities are respectively arranged on the second doped sub-layers of the corresponding conductive types.

4. The solar cell module according to claim 3, characterized by The back contact solar cell further comprises an isolation film layer; The isolation film layer is arranged between two adjacent first doped sub-layers; And / or, the isolation film layer is arranged between the first doped sub-layers of the opposite conductive types and the second doped sub-layers.

5. The solar cell module according to any one of claims 1 to 4, characterized by, An insulating adhesive layer is arranged between each of the grid bus bars and the collecting grid line with the opposite polarity; And / or, a plurality of the collecting grid lines with the same polarity are arrayed along the first direction, and the collecting grid lines with different polarities are staggered in the second direction, so that the bus grid lines are separated from the ends of the plurality of collecting grid lines with the opposite polarity.

6. The solar cell module according to any one of claims 1 to 4, characterized by, In the second direction, the size of the silicon substrate is W, the length of each of the collecting grid lines is L, and W:L=1:(0.9-0.99). And / or, the line width of the current collecting grid line is 0.1-10 μm; And / or, the number of the current collecting grid lines on each back contact solar cell is 10-2000; And / or, the distance between two adjacent current collecting grid lines in the first direction is 0.1-5 mm; And / or, the first direction is perpendicular to the second direction; And / or, the cross-sectional shape of the grid line busbar is circular, triangular, trapezoidal or rectangular; And / or, the grid line busbar is a tin-plated copper strip or a conductive composite material strip; And / or, the cross-sectional area of the gate line bus bar is 0.001 mm 2 ~ 2 mm 2 .

7. A solar cell string, characterized by The solar cell string comprises: The solar cell module according to any one of claims 1-6; and A plurality of series conductive members, which are connected in series with the solar cell module.

8. The solar cell string of claim 7, wherein, The series conductive member is an inter-sheet busbar, the number of the back contact solar cells is multiple, the multiple back contact solar cells are arranged in the second direction, at least one inter-sheet busbar is arranged between two adjacent back contact solar cells, and the inter-sheet busbar is electrically connected to the current collecting grid lines on the two back contact solar cells to connect the two back contact solar cells in series.

9. The solar cell string of claim 8, wherein, One end of the current collecting grid line connected to the busbar grid line is provided with a welding portion, multiple welding portions located on the same side of the silicon substrate are arranged at intervals in the first direction, the inter-sheet busbar extends along the first direction, and the inter-sheet busbar is welded to multiple welding portions to electrically connect the current collecting grid lines.

10. The solar cell string of claim 9, wherein, The inter-sheet busbar comprises a main body segment and multiple protruding segments, the main body segment extends along the first direction, multiple protruding segments are arranged on both sides of the main body segment in the second direction, multiple protruding segments located on the same side of the main body segment are arranged at intervals along the first direction, and each protruding segment is welded to each welding portion to electrically connect the current collecting grid lines; Or, the shape of the inter-sheet busbar is rectangular, and two side edges of the inter-sheet busbar are welded to multiple welding portions in the second direction to electrically connect the current collecting grid lines. And / or, the cross-sectional area of the inter-sheet bus bar is 0.001 mm 2 ~ 5 mm 2 ; And / or, the shape of the welding portion is circular, triangular, rectangular, pentagonal, hexagonal or trapezoidal.

11. The solar cell string of claim 7, wherein, The series conductive member is a solder strip, the number of the back contact solar cells is multiple, the multiple back contact solar cells are arranged in the second direction, each solder strip extends along the second direction and is laminated with the current collecting grid lines, one end of each current collecting grid line connected to the busbar grid line is provided with a welding portion, each solder strip is welded to the welding portions on two back contact solar cells to connect the two back contact solar cells in series, the grid line busbar is arranged on the side of the solder strip away from the back contact solar cell, and an insulating adhesive layer is arranged between each grid line busbar and the solder strip on the current collecting grid line with opposite polarity.

12. A photovoltaic module, characterized by The solar cell module according to any one of claims 1-6 or the solar cell string according to any one of claims 7-11.

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