Battery string and photovoltaic module

Abstract

A battery string and a photovoltaic module. The battery string comprises: a battery piece, at least one surface of the battery piece being provided with at least two joining portions arranged at an interval in a first direction; and an electrical connection line extending in the first direction. A joining layer is arranged on a surface of the electrical connection line facing the battery piece, and the joining portions are electrically connected to the electrical connection line by means of the joining layer. A first spreading width of the joining layer at each joining portion in a second direction perpendicular to the first direction is greater than a second spreading width along a second direction at an interval between two adjacent joining portions. The photovoltaic module comprises at least one battery string. The described battery string can maintain conductivity and stability between the electrical connection line and the joining portions, prevent the occurrence of a short circuit condition or reduce damage to electrodes on both sides.

Description

Battery string and photovoltaic module

[0001] The present application claims priority to the application with the application date of April 8, 2024, the application number of 2024207162580, and the invention name of Battery string and photovoltaic module, and the application with the application date of October 9, 2024, the application number of 202411405794.X, and the invention name of Battery string and photovoltaic module. The content recorded in the prior application is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0002] At least one embodiment of the present application relates to the field of photovoltaic technology, in particular to a battery string and a photovoltaic module. BACKGROUND

[0003] The surface of the solar cell is formed with a sub-grid, and part of the sub-grid is arranged in a multi-section structure with a gap to accommodate an electrical connection wire or an electrical connection wire and a main grid passing through the gap and connected to at least part of the sub-grid.

[0004] When the solar cells are interconnected, the electrical connection wire is welded to the joint by the soldering point formed by the bonding layer, thereby connecting different cell pieces in series to form a battery string. Due to the deformation of the cell piece during welding, subsequent processes such as layout and lamination are required to flatten the cell piece.

[0005] The bonding layer after lamination will spread under the action of pressure. The larger the spreading range of the part of the bonding layer forming the soldering point, the more conducive to maintaining the electrical connection and the reliability of the pull-out resistance of the electrical connection wire and the joint. However, if the spreading width of the part of the bonding layer located in the gap formed by the sub-grid, especially the spreading width along the gap direction, is too large, it may cause the electrical connection wire to be connected to the sub-grids on both sides, thereby causing short circuit or damage to the sub-grids on both sides. SUMMARY

[0006] Therefore, in order to at least partially solve the above-mentioned technical problems, the present application provides a battery string and a photovoltaic module.

[0007] In order to achieve the above-mentioned purpose, the technical solutions of the present application are as follows:

[0008] According to an embodiment of the present application, a battery string is provided, comprising: a cell piece, at least one surface of the cell piece having at least two joints arranged at intervals along a first direction; and an electrical connection wire extending along the first direction; wherein the surface of the electrical connection wire facing the cell piece is provided with a bonding layer, and the joint is electrically connected to the electrical connection wire through the bonding layer; the first spreading width of the bonding layer along a second direction perpendicular to the first direction at each joint is greater than the second spreading width of the bonding layer along the second direction at the interval between the adjacent two joints.

[0009] According to an embodiment of the present application, a photovoltaic module is provided, comprising at least one cell string.

[0010] According to the cell string and the photovoltaic module provided by the above-mentioned embodiments of the present application, different parts of the bonding layer arranged on the electric connection wire are configured to have different spreading widths. The part of the bonding layer between the electric connection wire and the bonding part is configured to have a first spreading width, and the part of the bonding layer between two adjacent bonding parts is configured to have a second spreading width. The first spreading width is larger, so that the electric connection wire and the bonding part have a larger pull-out resistance, so as to maintain the conductivity and stability between the electric connection wire and the bonding part. The second spreading width is smaller, so that the bonding layer is isolated from the electrodes on both sides of the cell sheet, so as to prevent the short circuit or reduce the damage to the electrodes on both sides. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, but not limit the present application.

[0012] FIG. 1 is a top view of a cell string formed by a back contact solar cell according to an embodiment of the present application;

[0013] FIG. 2 is a partial structure view of the cell string of the embodiment shown in FIG. 1;

[0014] FIG. 3A is a partial cross-sectional view of the embodiment shown in FIG. 2 along A-A direction;

[0015] FIG. 3B is a partial cross-sectional view of the embodiment shown in FIG. 2 along B-B direction;

[0016] FIG. 4 is a top view of a cell string formed by a back contact solar cell according to another embodiment of the present application;

[0017] FIG. 5 is a partial structure view of the cell string of the embodiment shown in FIG. 4;

[0018] FIG. 6 is a partial cross-sectional view of the embodiment shown in FIG. 5 along B1-B2 direction;

[0019] FIG. 7 is a partial cross-sectional view of a cell string along a second direction according to still another embodiment of the present application;

[0020] FIG. 8 is a top view of a cell string formed by a double-sided solar cell according to an embodiment of the present application;

[0021] FIG. 9 is a partial structure view of the cell string of the embodiment shown in FIG. 8;

[0022] FIG. 10A is a partial cross-sectional view of the embodiment shown in FIG. 9 along A1-A2 direction;

[0023] Fig. 10B is a partial sectional view of the embodiment shown in Fig. 9 in the B1-B2 direction;

[0024] Fig. 11 is a schematic plan view of a cell string formed by a double-sided solar cell according to another embodiment of the present application;

[0025] Fig. 12 is a schematic partial structure view of the cell string according to the embodiment shown in Fig. 11;

[0026] Fig. 13 is a partial sectional view of the embodiment shown in Fig. 12 in the B1-B2 direction;

[0027] Fig. 14 is a schematic partial sectional view of a solar cell according to an embodiment of the present application before encapsulation;

[0028] Fig. 15 is a schematic partial sectional view of a solar cell according to an embodiment of the present application after encapsulation.

[0029] Reference Signs: 1 - cell; 2 - electrical connection line; 3 - first electrode; 4 - second electrode; 5 - joint; 51 - first joint; 52 - second joint; 6 - connection portion; 7 - third electrode; 81 - first portion of joint layer; 82 - second portion of joint layer; 9 - frame; 91 - protrusion; 11 - first adhesive film; 12 - second adhesive film; 13 - first adhesive film; 14 - second adhesive film; 15 - cover plate; 16 - back sheet; 21 - copper base; 22 - solder. DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions, and advantages of the present application clearer, the following will further describe the present application with reference to the embodiments and the accompanying drawings.

[0031] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to one skilled in the art that one or more embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and functions have been omitted to avoid unnecessarily complicating the present application with details that will be readily understood by those skilled in the art.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the term "includes" indicates the presence of the features, steps, operations, but does not exclude the presence or addition of one or more other features.

[0033] In the event that a statement similar to "at least one of A, B, and C, etc." is used, the general intent that should be followed is to interpret the statement in the manner that a person of ordinary skill in the art would understand the statement in context. For example, the statement "a system having at least one of A, B, or C" should be interpreted to include, among other things, a system that has only A, a system that has only B, a system that has only C, a system that has both A and B, a system that has both A and C, a system that has both B and C, and / or a system that has all of A, B, and C, etc.

[0034] In the present application, the relative positions between two components (e.g., film layers or regions) such as "on", "above", or "over" can refer to the two components being in direct contact, or can refer to the two components being in indirect contact. Similarly, in the present application, the relative positions between two components such as "under", "below", or "underneath" can refer to the two components being in direct contact, or can refer to the two components being in indirect contact. For example, when one component (e.g., a film layer or region) is referred to as "on" another component, it can be directly on the other component, or there can be intervening components between the two. On the other hand, when a component is referred to as "directly on" another component, there are no intervening components between the two. In addition, when one component is referred to as "on" another component, the two are in a top-to-bottom relationship in a plan view, and the component can be above or below the other component, so the top-to-bottom relationship depends on the orientation of the device.

[0035] In a back contact solar cell, both the positive electrode (also referred to as the first electrode or the first busbar) and the negative electrode (also referred to as the second electrode or the second busbar) are disposed on the back surface of the cell piece. For this purpose, busbars of different polarities are arranged on different doped regions of the cell piece, and the busbars are arranged in a multi-segment structure with gaps to accommodate the electrical connection wires or the electrical connection wires and the main busbar passing through the gaps and connected to the busbar of the corresponding polarity to collect the current collected by the busbar. The electrical connection wires are then soldered to the junctions (e.g., solder pads) of different back contact solar cells to connect the different back contact solar cells in series, thereby forming a cell string.

[0036] In a bifacial solar cell, a first electrode and a second electrode are respectively arranged on a first surface and a second surface of a cell piece. A main grid is used to connect a sub-grid of the same polarity to collect the current collected by the electrodes. Then, the electrically connecting wire is welded with the junction (e.g. a soldering pad) of a different bifacial solar cell to connect the different bifacial solar cells in series to form a cell string.

[0037] At present, the junction layer (including but not limited to solder) for welding the electrically connecting wire and the soldering pad is usually set point by point along the extension direction of the electrically connecting wire according to the welding position by a welding gun or other welding equipment for welding use. During welding, the cell piece will deform to a certain extent. Therefore, the cell piece needs to be flattened through subsequent layout and lamination processes. The junction layer will spread around under the action of pressure.

[0038] The spreading width of the junction layer along the gap formed by the sub-grid needs to be particularly concerned. If the width is too small, the conductivity and reliability between the junction and the electrically connecting wire will be affected. If the width is too large, the junction layer located in the gap formed by the sub-grid will be in contact with the sub-grid on both sides, thereby affecting the sub-grid on both sides.

[0039] Therefore, based on the same inventive concept, how to provide a cell string and a photovoltaic module, which maintains the electrical connection and the reliability of the anti-pulling of the electrically connecting wire and the junction, and avoids connection with the sub-grid on both sides, becomes a technical problem to be solved.

[0040] According to an exemplary embodiment of the present application, the present application provides a cell string and a photovoltaic module, the cell string comprising:

[0041] a cell piece, at least one surface of the cell piece having at least two junctions arranged at intervals along a first direction; and

[0042] an electrically connecting wire extending along the first direction;

[0043] The surface of the electrically connecting wire facing the cell piece is provided with a junction layer, and the junctions are electrically connected to the electrically connecting wire through the junction layer. The first spreading width of the junction layer on each junction along a second direction perpendicular to the first direction is greater than the second spreading width of the junction layer at the interval between the adjacent two junctions along the second direction.

[0044] According to an embodiment of the present application, the solar cell type can be a back contact solar cell, including but not limited to any one of an interdigitated back contact (IBC), a hybrid BC (joint passivation BC), a low-temperature interdigitated back contact heterojunction solar cell (HBC), a tunneling oxide passivated contact back contact (TBC), a polycrystalline silicon on oxide interdigitated back contact (POLO-IBC); or can be a bifacial solar cell, for example, can be a heterojunction with intrinsic thin-layer (HJT) cell.

[0045] FIG. 1 is a top view of a cell string formed by a back contact solar cell according to an embodiment of the present application.

[0046] FIG. 2 is a partial structure diagram of the cell string of the embodiment shown in FIG. 1.

[0047] According to an exemplary embodiment of the present application, a cell string formed by a back contact solar cell is provided, as shown in FIGS. 1 and 2, including a cell sheet 1 and an electrical connection wire 2. The cell sheet 1 has opposite first and second surfaces, and the second surface of the cell sheet 1 has at least two junctions 5 arranged at intervals along a first direction. The electrical connection wire 2 extends along the first direction and is joined to the surface of the cell sheet 1 and electrically connected to the at least two junctions 5. The surface of the electrical connection wire 2 facing the cell sheet 1 is provided with a junction layer, the junction layer including a first portion 81 in FIG. 3A and a second portion 82 in FIG. 3B, and the junction 5 is electrically connected to the electrical connection wire 2 through the junction layer. The first spreading width of the junction layer along a second direction between the electrical connection wire 2 and the junction 5 is greater than the second spreading width of the junction layer along the second direction between adjacent two junctions 5, and the first direction is orthogonal to the second direction.

[0048] That is, the first spreading width of the junction layer along the second direction perpendicular to the first direction on each junction 5 is greater than the second spreading width of the junction layer along the second direction at the interval between adjacent two junctions 5.

[0049] In an illustrative embodiment, the battery tab 1 includes, but is not limited to, a structure configured substantially rectangular (only a portion of the battery tab 1 is shown in FIG. 2), including a first side extending along a first direction (e.g., the up-and-down direction as shown in FIG. 2) and a second side extending along a second direction (e.g., the left-and-right direction as shown in FIG. 2). Herein, the first side can serve as a long side of the battery tab 1, and the second side can serve as a short side of the battery tab 1. It should be understood that embodiments of the present application are not limited thereto.

[0050] For example, the joint 5 includes, but is not limited to, a substantially rectangular shape configured with a chamfer, a polygonal shape, a circular shape, an elliptical shape, a racetrack shape, or any other arbitrary shape suitable for connecting with the electrical connection wire 2 (i.e., a solder strip). For example, the joint 5 includes, but is not limited to, a solder pad.

[0051] In an illustrative embodiment, as shown in FIGS. 1-2, the battery tab 1 is provided with a plurality of joints 5 (only one is shown in FIG. 2). Further, the plurality of joints 5 are spaced apart along the first direction (e.g., the up-and-down direction as shown in FIG. 2). Herein, the plurality of joints 5 can be equally spaced apart along the first direction; or at least a portion of the joints 5 can be provided with different spacings from other joints 5 (e.g., the joints 5 provided at the middle portion of the battery tab 1 can be equally spaced apart, while the joints 5 provided at the edge of the battery tab 1 can be provided with different spacings from adjacent joints 5).

[0052] FIG. 3A is a partial cross-sectional view of the embodiment shown in FIG. 2 along the A-A direction.

[0053] FIG. 3B is a partial cross-sectional view of the embodiment shown in FIG. 2 along the B-B direction.

[0054] In an illustrative embodiment, as shown in FIGS. 3A and 3B, the surface of the electrical connection wire 2 (i.e., a solder strip) facing the battery tab 1 (i.e., the lower surface as shown in FIGS. 3A and 3B) is provided with a joint layer. In detail, the joint layer includes, but is not limited to, a solder (e.g., solder paste and / or other joint material).

[0055] In an illustrative embodiment, as shown in FIGS. 3A and 3B, the joint layer includes a first portion 81 provided between the electrical connection wire 2 (i.e., a solder strip) and the joint 5, and a second portion 82 provided between the electrical connection wire 2 (i.e., a solder strip) and the battery tab 1. In detail, a first spreading width (i.e., d1) of the first portion 81 spreading along the second direction (e.g., the left-and-right direction as shown in FIG. 3A) is configured to be greater than a second spreading width (i.e., d3) of the second portion 82, i.e., d1>d3.

[0056] In such an embodiment, by setting the first portion 81 and the second portion 82 of the bonding layer to have different spreading widths, the bonding layer can be adapted to the requirements of spreading width at different positions on the battery sheet 1. The first portion 81 serves as a solder joint for connecting the electrical connecting wire 2 (i.e. the solder strip) to the bonding portion 5, and the first spreading width is configured to be greater than the second spreading width. On the basis of providing good solderability, the larger spreading area of the first portion 81 can provide greater pull-out resistance for the electrical connecting wire 2 (i.e. the solder strip), which is conducive to improving the electrical conductivity and stability between the electrical connecting wire 2 (i.e. the solder strip) and the bonding portion 5; while the second portion 82 with the smaller second spreading width is conducive to isolating the electrical connecting wire 2 from the electrodes of different polarities of the battery sheet 1, so as to avoid short circuit.

[0057] According to an embodiment of the present application, as shown in FIGS. 3A and 3B, the ratio of the second spreading width to the first spreading width is configured to be 0.2 / 0.8-0.6 / 0.8, for example, can be 0.2 / 0.8, 0.3 / 0.8, 0.4 / 0.8, 0.5 / 0.8, 0.6 / 0.8, but is not limited to the values given.

[0058] In an illustrative embodiment, as shown in FIGS. 3A and 3B, d3 / d1 includes but is not limited to being configured to be 0.2 / 0.8-0.6 / 0.8. Further, the spreading width (including the first spreading width and the second spreading width) of the bonding layer along the second direction (e.g. the left-right direction as shown in FIGS. 3A and 3B) is positively correlated with the thickness of the configured bonding layer, that is, the thicker the bonding layer, the greater the spreading width after bonding. Therefore, the thickness of the bonding layer needs to be limited.

[0059] For example, for the electrical connecting wire 2 configured to have a width of 0.3mm-0.6mm, the thickness of the bonding layer before bonding includes but is not limited to being configured to be 0.01mm-0.05mm; based on the above thickness of the bonding layer, the thickness of the first portion 81 of the bonding layer after bonding can be maintained at 0.005mm-0.03mm.

[0060] According to an embodiment of the present application, as shown in FIGS. 1-2, 3A-3B, the battery sheet 1 further includes a plurality of first electrodes 3 and a plurality of second electrodes 4 extending along the second direction on the second surface, the plurality of first electrodes 3 and the plurality of second electrodes 4 are sequentially and alternately arranged along the first direction, and the first electrodes 3 are connected to the bonding portion 5 or the electrical connecting wire 2.

[0061] According to an embodiment of the present application, as shown in FIGS. 1-2, 3B, at least a portion of the second electrode 4 is discontinuous in the second direction and the discontinuous positions form a disconnection. The electrical connection line 2 passes through the disconnection, and the joint 5 extends into a portion of the disconnection. At the disconnection positions, the positions of the second electrode 4 close to the third electrode 7 can be provided with an insulating block for the insulation of the electrical connection line 2 and the second electrode 4.

[0062] According to an embodiment of the present application, as shown in FIGS. 1-2, a portion of the disconnection forms a first gap, and another portion of the disconnection forms a second gap, and the joint 5 is arranged in the disconnection forming the first gap. Among them, the width of the first gap is configured to be greater than the width of the second gap.

[0063] In an illustrative embodiment, as shown in FIGS. 1 and 2, the first electrode 3 (i.e., the sub-grid with the same polarity as the joint 5) and the second electrode 4 (i.e., the sub-grid with a different polarity from the joint 5) are arranged on the back of the battery piece 1 (i.e., the face facing the viewing angle as shown in FIG. 1). In detail, a plurality of first electrodes 3 and a plurality of second electrodes 4 are arranged alternately and spaced apart in the first direction (i.e., the up-down direction as shown in FIG. 2) to form an interdigital structure to adapt to the different doped regions (such as p+ doped regions and n+ doped regions) arranged in parallel and spaced apart on the back of the battery piece 1.

[0064] According to an embodiment of the present application, as shown in FIG. 2, the battery string further comprises a connecting portion 6 extending in the second direction, the connecting portion 6 connecting the joint 5 and a portion of the first electrode 3.

[0065] In an illustrative embodiment, as shown in FIG. 2, the width of the distal end of the connecting portion 6 away from the joint 5 (i.e., the left end of the connecting portion 6 on the left side and the right end of the connecting portion 6 on the right side in FIG. 2) is configured to be smaller than the width of the proximal end close to the joint 5 (i.e., the right end of the connecting portion on the left side and the left end of the connecting portion on the right side) (i.e., the distance between the upper end and the lower end of the connecting portion 6 as shown in FIG. 2).

[0066] For example, the connecting portion 6 can be arranged in a substantially triangular structure.

[0067] For example, the shape of the connecting portion 6 is a triangle with a cross-section gradually decreasing from one end close to the joint 5 to one end away from the joint 5.

[0068] For another example, the connecting portion 6 can be arranged in a substantially trapezoidal structure.

[0069] For example, the shape of the connecting portion 6 is a trapezoid with a cross-section gradually decreasing from one end close to the joint 5 to one end away from the joint 5.

[0070] In such an embodiment, the proximal end of the connecting portion 6 is configured to have a larger width, which increases the width of the connecting portion of the first electrode 3 and the junction 5, thereby preventing the connecting portion of the first electrode 3 and the junction 5 from being fused and preventing current from being concentrated, and thus improving the current collection effect.

[0071] In an illustrative embodiment, as shown in FIGS. 1 and 2, each of the second electrodes 4 (i.e., the auxiliary grid having a different polarity from the junction 5) has a plurality of electrode segments arranged at intervals along a second direction (i.e., the left-right direction as shown in FIG. 2). In detail, a disconnection portion is formed between two adjacent electrode segments.

[0072] According to an embodiment of the present application, as shown in FIGS. 2 and 3B, the battery string further includes a third electrode 7 extending along the first direction on the second surface, the third electrode 7 passing through the partial disconnection portion and connecting at least two adjacent junctions 5. The portion of the junction layer between the third electrode 7 and the electrical connection line 2 is configured to have a second spreading width.

[0073] In an illustrative embodiment, as shown in FIG. 2, the third electrode 7 (i.e., the main grid) is uniformly spaced with a plurality of junctions 5 along a first direction (i.e., the up-down direction as shown in FIG. 2). In detail, the junction 5 includes but is not limited to a structure configured to be substantially strip-shaped.

[0074] In an illustrative embodiment, as shown in FIGS. 2 and 3B, the third electrode 7 (i.e., the main grid) extends along the first direction (i.e., the up-down direction as shown in FIG. 2). In detail, the third electrode 7 (i.e., the main grid) passes through the formed disconnection portion of the second electrode 4 having a different polarity and is connected to the first electrode 3 having the same polarity. Further, the junction layer covers the third electrode 7 (i.e., the main grid).

[0075] In an illustrative embodiment, as shown in FIGS. 3A and 3B, the first spreading width (i.e., d1) of the first portion 81 is configured to be smaller than the width (i.e., d2) of the junction 5, and the width (i.e., d3) of the second portion 82 is configured to be smaller than the width of the disconnection portion (i.e., d4) formed by the second electrode 4. That is, d2>d1, d4>d3, and d1>d3.

[0076] In an illustrative embodiment, the electrode segments of the second electrode 4 located on both sides of the junction 5 form a first gap, and the second electrode 4 located on both sides of the third electrode 7 forms a second gap. The width of the first gap (refer to L1 in FIG. 2) is configured to be greater than the width of the junction 5, the width of the second gap (refer to L2 in FIG. 2) is configured to be greater than the width of the electrical connection line 2, and the width of the first gap is configured to be greater than the width of the second gap (i.e., L1>L2).

[0077] In such an embodiment, the disconnecting portion of the second electrode 4 is configured to have different width gaps (i.e. first gap and second gap) to accommodate the width of the third electrode 7 and the bonding portion 5, so as to effectively maintain the isolation between the second electrode 4 and the third electrode 7 and / or the bonding portion 5 of different polarity, to avoid short circuit.

[0078] In an exemplary embodiment, as shown in FIG. 3A, the width of the bonding portion 5 (i.e. d2) includes but is not limited to being configured as 1.2mm-1.3mm. Correspondingly, the width of the third electrode 7 (i.e. main grid) includes but is not limited to being configured as 50μm-90μm.

[0079] Due to the precision limitation of the soldering gun and / or other soldering equipment, it is inevitable that the bonding layer will be offset from the center line of the electrical connecting wire 2 (i.e. in the orthographic projection in the thickness direction of the battery sheet 1, the center line of the bonding layer is offset from the center line of the electrical connecting wire 2 in the first direction), so that at least a portion of the bonding layer contacts the passivation layer on the surface of the battery sheet 1 (e.g. if the bonding layer is offset to the left relative to the electrical connecting wire 2 as shown in FIG. 3A, then the left end of the bonding layer is located on the passivation layer). The passivation layer includes an oxidation layer, a nitridation layer, etc. formed on the surface of the battery sheet 1, to avoid the surface of the battery sheet 1 from being corroded and damaged by the external environment, and the passivation material for forming the passivation layer includes but is not limited to SiN or Al2O3.

[0080] Based on the above size configuration, the offset of the bonding layer due to the equipment precision can be compensated, i.e. when the bonding layer is offset relative to the center line of the electrical connecting wire 2 (i.e. solder strip), the bonding layer does not contact the second electrode 4 in the offset direction.

[0081] FIG. 4 is a top view of a cell string formed by a back contact solar cell according to another embodiment of the present application, showing a back contact solar cell without a main grid.

[0082] FIG. 5 is a partial structure view of the cell string according to the embodiment shown in FIG. 4.

[0083] FIG. 6 is a partial cross-sectional view of the embodiment shown in FIG. 5 along the direction of B1-B2.

[0084] In another exemplary embodiment, as shown in FIGS. 4-6, the first electrode 3 is directly connected to the electrical connecting wire 2, so that the current collected by the first electrode 3 is directly collected through the electrical connecting wire 2. In this way, the screen printing design of the electrode is simplified, and the paste (e.g. silver) used for printing the third electrode 7 (i.e. main grid) is saved.

[0085] According to an embodiment of the present application, the bonding portion 5 comprises a first bonding portion 51 and a second bonding portion 52, wherein, along the first direction, the first bonding portion 51 is distributed near the edge of the battery sheet 1, and the size of the first bonding portion 51 is greater than the size of the second bonding portion 52.

[0086] Optionally, the electric connection wire 2 comprises a metal core layer and a solderable metal layer (e.g. tin-lead, tin-lead-bismuth, tin-silver-bismuth alloy layer) wrapped outside the metal core layer (e.g. copper layer), the thickness of the metal core layer can be 140-300 microns, and the thickness of the solderable metal layer can be 10-50 microns. The materials of the first bonding portion 51 and the second bonding portion 52 are both from the solderable metal layer of the electric connection wire 2, and no additional bonding material needs to be arranged at the position of the bonding portion 5, i.e. the bonding layer of the first bonding portion 51 and the second bonding portion 52 is integrated with the electric connection wire 2, and there is no layered structure in the vertical direction. In this way, the bonding material and the process steps can be saved, while the soldering pull-off force and the electric connection reliability are ensured.

[0087] According to an embodiment of the present application, the area of the first bonding portion 51 is greater than the area of the second bonding portion 52. The first bonding portion 51 is distributed near the edge of the battery sheet 1, and the silicon sheet edge serves as the starting point and the ending point of the soldering, and thus the pull-off force is the greatest. By setting the area of the first bonding portion 51 to be greater, the electric connection wire 2 and the first bonding portion 51 have a greater pull-off resistance, so as to maintain the stability of the electric connection wire 2 and the first bonding portion 51.

[0088] According to an embodiment of the present application, the width of the first bonding portion 51 along the first direction is greater than the width of the second bonding portion 52 along the first direction, and the length of the first bonding portion 51 along the second direction is equal to or slightly smaller than the length of the second bonding portion 52 along the second direction. The second bonding portion 53 has a smaller width, which can ensure the electrical interconnection with the electric connection wires at multiple positions, and can also reduce the contact resistance between the bonding portion and the electric connection wire.

[0089] For example, referring to FIG. 4, the bonding portion 5 comprises a first bonding portion (i.e. large pad) 51 located at the edge of the battery sheet and a second bonding portion (i.e. small pad) 52 located inside the battery sheet, and the width of the second bonding portion 52 along the first direction is smaller than the width of the first bonding portion 51 along the first direction.

[0090] FIG. 7 is a partial cross-sectional view of the battery string along the second direction according to another embodiment of the present application.

[0091] According to an embodiment of the present application, as shown in FIG. 7, the battery string further comprises a surrounding frame 9 arranged on the part of the battery sheet 1 outside the bonding portion 5, and the side of the surrounding frame 9 facing the bonding portion 5 forms a protruding portion 91 which is crimped to the first surface of the bonding portion 5 away from the battery sheet 1.

[0092] According to the embodiment of the present application, as shown in Fig. 7, the spacing between two protrusions 91 of the frame 9 facing each other in the second direction is greater than the width of the electric connection line 2.

[0093] According to the embodiment of the present application, as shown in Fig. 7, the bonding layer (not shown in the figure) is fused with the tin layer of the electric connection line 2.

[0094] In an exemplary embodiment, as shown in Fig. 7, the frame 9 is arranged on the battery sheet 1 outside the bonding portion 5 in response to the shape of the bonding portion 5. In detail, the upper portion of the frame 9 as shown in Fig. 7 forms a protrusion 91 protruding to the side of the bonding portion 5, so that the frame 9 forms a cross-section structure similar to "L shape" in the cross-section shown in Fig. 7. Further, the protrusion 91 abuts against the first surface (i.e. the upper surface as shown in Fig. 7) of the bonding portion 5, thereby limiting the bonding portion 5 between the frame 9 and the battery sheet 1. It should be understood that the frame 9 is not limited to be made of aluminum.

[0095] In an exemplary embodiment, the frame 9 is also configured as a substantially rectangular frame structure in response to the bonding portion 5 being configured as a rectangle. It should be understood that the embodiment of the present application is not limited thereto.

[0096] The frame 9 can also be configured as a frame structure different from the external shape of the bonding portion 5. For example, the frame 9 can form a semi-enclosing or intermittent structure abutting against part of the edge of the bonding portion 5.

[0097] Fig. 8 is a top view of a battery string formed by the double-sided solar cell according to the embodiment of the present application.

[0098] Fig. 9 is a partial structure view of the battery string according to the embodiment shown in Fig. 8.

[0099] Fig. 10A is a partial cross-section view of the A1-A2 direction according to the embodiment shown in Fig. 9.

[0100] Fig. 10B is a partial cross-section view of the B1-B2 direction according to the embodiment shown in Fig. 9.

[0101] According to an example embodiment of the present application, the present application provides a double-sided solar cell formed battery string, as shown in FIG. 8 and FIG. 9, comprising a battery piece 1 and an electrical connection line 2. The battery piece 1 has opposite first and second surfaces, and the first and / or second surface has at least two junctions 5 arranged along a first direction. The electrical connection line 2 extends along the first direction and is connected to the surface of the battery piece 1 and is electrically connected to the at least two junctions 5. The surface of the electrical connection line 2 facing the battery piece 1 is provided with a junction layer, and the junctions 5 are electrically connected to the electrical connection line 2 through the junction layer. The first spread width of the junction layer between the electrical connection line 2 and the junctions 5 along a second direction perpendicular to the first direction is greater than the second spread width of the junction layer between adjacent two junctions 5 along the second direction.

[0102] According to an example embodiment of the present application, as shown in FIG. 10A and FIG. 10B, the ratio of the second spread width to the first spread width is configured to be 0.2 / 0.8-0.6 / 0.8, for example, can be 0.2 / 0.8, 0.3 / 0.8, 0.4 / 0.8, 0.5 / 0.8, 0.6 / 0.8, but is not limited to the values given.

[0103] According to an example embodiment of the present application, the battery piece 1 further comprises a plurality of first electrodes 3 extending along the second direction on the first surface, and the first electrodes 3 are connected to the junctions 5 or the electrical connection line 2; and a plurality of second electrodes 4 extending along the second direction on the second surface, and the second electrodes 4 are connected to the junctions 5 or the electrical connection line 2.

[0104] According to an example embodiment of the present application, as shown in FIG. 8 and FIG. 9, the double-sided solar cell formed battery string further comprises a third electrode 7 extending along the first direction on the first and / or second surface of the battery piece 1, and the third electrode 7 connects adjacent at least two junctions 5; and the part of the junction layer between the third electrode 7 and the electrical connection line 2 is configured to have the second spread width.

[0105] According to an example embodiment of the present application, in the double-sided solar cell, the part of the junction layer between the electrical connection line and the junctions is configured to have the first spread width, and the part of the junction layer between adjacent two junctions is configured to have the second spread width. The larger first spread width can make the electrical connection line and the junctions have larger pull-out resistance to maintain the electrical conductivity and stability between the electrical connection line and the junctions; and the smaller second spread width can reduce the contact resistance between the electrical connection line and the electrodes on both sides and can reduce the damage to the electrodes on both sides.

[0106] FIG. 11 is a top view of a double-sided solar cell formed battery string according to another example embodiment of the present application.

[0107] FIG. 12 is a partial structure diagram of the battery string of the example embodiment shown in FIG. 11.

[0108] Fig. 13 is a partial cross-sectional view of the embodiment shown in Fig. 12 along the B1-B2 direction.

[0109] In another illustrative embodiment, as shown in Figs. 11-13, the first electrode 3 and / or the second electrode 4 is directly connected to the electrical connecting wire 2, so that the current collected by the first electrode 3 and / or the second electrode 4 is directly collected through the electrical connecting wire 2. In this way, the screen printing design of the printed electrode is facilitated, and the paste (e.g., silver) used for printing the third electrode 7 (i.e., the main grid) is saved.

[0110] According to the embodiment of the present application, the above-mentioned battery string further comprises at least one adhesive film, which is suitable for covering the electrical connecting wire 2 and at least part of the battery sheet 1. By covering the adhesive film on the electrical connecting wire 2, the electrical connecting wire 2 is fixed on the battery sheet 1.

[0111] Fig. 14 is a partial cross-sectional view of the solar cell before encapsulation according to the embodiment of the present application.

[0112] Fig. 15 is a partial cross-sectional view of the solar cell after encapsulation according to the embodiment of the present application.

[0113] As shown in Fig. 14, for a bifacial solar cell, the electrical connecting wire 2 is formed on the first surface and the second surface of the battery sheet 1 respectively, the first adhesive film 11 is covered on the electrical connecting wire 2 on the first surface, and the second adhesive film 12 is covered on the electrical connecting wire 2 on the second surface, so as to ensure that the electrical connecting wire 2 on both surfaces is attached to the surface of the battery sheet 1. The first adhesive film 13 is covered on the cover plate 15, and the second adhesive film 14 is covered on the back plate 16. As shown in Fig. 15, for a back contact solar cell, the electrical connecting wire 2 is arranged on the second surface (corresponding to the back surface / backlight surface), and the first adhesive film 11 is covered on the electrical connecting wire 2 on the second surface, so as to ensure that the electrical connecting wire 2 is attached to the surface of the battery sheet 1, so as to realize the spreading of the interconnection layer in the above-mentioned spreading mode.

[0114] As shown in Fig. 14, the first adhesive film 11 and / or the first adhesive film 13 is attached, and the second adhesive film 12 and the second adhesive film 14 is attached, and then laminated in a heating cavity. The electrical connecting wire 2 is composed of a copper base 21 (i.e., a metal core layer) and a solder 22 (i.e., a solderable metal layer), and the solder 22 is melted in the heating cavity to realize the interconnection between the auxiliary grid on the surface of the battery sheet 1 and the electrical connecting wire 2. The first adhesive film 11 and the first adhesive film 13 are adhered to connect the battery sheet 1 and the cover plate 15, and the second adhesive film 12 and the second adhesive film 14 are adhered to connect the battery sheet 1 and the back plate 16.

[0115] Optionally, the electric connecting wire 2 comprises a metal core layer and a solderable metal layer covering the outside of the metal core layer. The material of the first joint 51 and the second joint 52 is from the solderable metal layer of the electric connecting wire 2, and no additional joint material is needed at the position of the joint 5, i.e. the joint layer of the first joint 51 and the second joint 52 is integral with the electric connecting wire 2, and is not layered in the vertical direction. In this interconnection structure, the first adhesive film 11 and / or the second adhesive film 12 is used.

[0116] In some embodiments (not shown in the figures), the electric connecting wire 2 can also be fixed on the surface of the cell sheet 1 by adhesive dots, which is also applicable to the string welding process of bifacial solar cells and back contact solar cells. Specifically, the electric connecting wire 2 can be first pre-pressed or pre-welded to the second surface (for back contact cells) or the first and second surfaces (for bifacial solar cells) of the cell sheet 1, then fixed by multiple discrete adhesive dots, and the stable joint of the electric connecting wire 2 is completed during lamination. Alternatively, multiple adhesive dots can be provided on the cell sheet 1, then the electric connecting wire 2 is fixed on the surface (the first surface and / or the second surface) of the cell sheet 1 by the multiple adhesive dots, and the stable joint of the electric connecting wire 2 is completed during lamination. By the above means, the similar joint layer morphology can also be obtained.

[0117] According to a photovoltaic module provided by the present application, not shown in the figures, it comprises at least one cell string.

[0118] In an illustrative embodiment, not shown in the figures, the photovoltaic module comprises multiple cell strings. In detail, the multiple cell strings are arranged at intervals. Further, the multiple back contact cells in each cell string are arranged in columns. The electric connecting wire interconnects the cell sheets in the same cell string.

[0119] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., are used to modify the corresponding elements, and do not mean that the elements have any ordinal number, nor represent the order of one element relative to another element or the order of the manufacturing method. These ordinal numbers are only used to clearly distinguish one element with a certain name from another element with the same name.

[0120] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the present application, and it should be understood that the above description is only for specific embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A battery string, characterized in that: include: A battery cell (1), wherein at least one surface of the battery cell (1) has at least two joint portions (5) spaced apart along a first direction; as well as an electrical connection line (2), extending along the first direction; Wherein, a bonding layer is provided on the surface of the electrical connection line (2) facing the battery cell (1), and the bonding portion (5) is electrically connected to the electrical connection line (2) via the bonding layer; The first spreading width of the bonding layer on each bonding portion (5) along a second direction perpendicular to the first direction is greater than the second spreading width of the bonding layer at the interval between two adjacent bonding portions (5) along the second direction.

2. The battery string according to claim 1, characterized in that: A ratio of the second spread width to the first spread width is configured to be 0.2 / 0.8 to 0.6 / 0.

8.

3. The battery string according to claim 1, characterized in that: The battery cell (1) has a first surface and a second surface opposite to each other, The battery cell further comprises a plurality of first electrodes (3) and a plurality of second electrodes (4) extending along the second direction on the second surface, wherein the plurality of first electrodes (3) and the plurality of second electrodes (4) are alternately arranged in sequence along the first direction, and the first electrodes (3) are connected to the joint portion (5) or the electrical connection line (2).

4. The battery string according to claim 3, characterized in that: At least a portion of the second electrode (4) forms a disconnected portion in the second direction; The electrical connection line (2) passes through the disconnection portion, and the joint portion (5) extends into a portion of the disconnection portion.

5. The battery string according to claim 4, characterized in that: It also includes a third electrode (7) extending along the first direction, the third electrode (7) passing through part of the disconnected portion and connecting at least two adjacent joining portions (5); The portion of the bonding layer located between the third electrode (7) and the electrical connection line (2) is configured to have the second spreading width.

6. The battery string according to claim 1, characterized in that: The battery cell (1) has a first surface and a second surface opposite to each other; The battery cell further comprises a plurality of first electrodes (3) extending along the second direction on the first surface, the first electrodes (3) being electrically connected to the joint (5) or the electrical connection line (2); as well as A plurality of second electrodes (4) extending along the second direction on the second surface, wherein the second electrodes (4) are electrically connected to the joint (5) or the electrical connection line (2).

7. The battery string according to claim 6, characterized in that: It also includes a third electrode (7) located on the first surface and / or the second surface and extending along the first direction, wherein the third electrode (7) connects at least two adjacent joining portions (5); The portion of the bonding layer located between the third electrode (7) and the electrical connection line (2) is configured to have the second spreading width.

8. The battery string according to claim 1, characterized in that: The joining portion (5) includes a first joining portion (51) and a second joining portion (52), Wherein, along the first direction, the first joining portion (51) is distributed near the edge of the battery cell (1), the second joining portion is located on the inner side of the battery cell, and the size of the first joining portion (51) is larger than the size of the second joining portion (52).

9. The battery string according to claim 1, characterized in that: Also includes: At least one adhesive film is suitable for covering the electrical connection line (2) and at least a portion of the battery cell (1).

10. A photovoltaic module, characterized in that: The method comprises at least one battery string according to any one of claims 1 to 9.

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