Battery strings and photovoltaic modules

Abstract

The present application provides a cell string and photovoltaic module, belonging to the field of solar cell technology. The cell string includes: a cell, at least one surface of which has at least two joints spaced apart along a first direction; and an electrical connection line extending along the first direction; wherein a bonding layer is provided on the surface of the electrical connection line facing the cell, and the joints are electrically connected to the electrical connection line via the bonding layer; the bonding layer has a first spreading width along a second direction perpendicular to the first direction at each joint, which is greater than a second spreading width along the second direction at the interval between two adjacent joints. The photovoltaic module includes at least one cell string.

Description

[0001] This application claims the priority right of April 8, 2024, application number 2024207162580, and invention name is "Battery String and Photovoltaic Module". All the contents recorded in the prior application are cited in this application by reference. Technical Field

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

[0003] A secondary grid is formed on the surface of the solar cell, and part of the secondary grid is arranged into a multi-segment structure with gaps to accommodate electrical connection wires or electrical connection wires and main grids passing through the gaps and connected to at least part of the secondary grid.

[0004] When interconnecting solar cells, electrical wires are soldered to the joints through the bonding layer, thus connecting the different cells in series to form a cell string. Because the cells deform during soldering, subsequent processes such as layout and lamination are required to flatten the cells.

[0005] After lamination, the bonding layer will spread outwards under pressure. The larger the spreading range of the bonding layer portion forming the solder joint, the more conducive it is to maintaining the electrical connection between the electrical connection wire and the bonding portion and the reliability of the pull-out resistance. However, if the spreading width of the bonding layer portion located within the gap formed by the auxiliary grid, especially the spreading width along the gap direction, is too large, it may cause the electrical connection wire to connect with the auxiliary grids on both sides, thereby causing a short circuit or damage to the auxiliary grids on both sides. Summary of the Invention

[0006] In view of this, 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 objectives, the technical solutions of this application are as follows:

[0008] According to an embodiment of one aspect of the present application, a battery string is provided, comprising: a battery cell, at least one surface of the battery cell having at least two joints spaced apart along a first direction; and an electrical connection line extending along the first direction; wherein a surface of the electrical connection line facing the battery cell is provided with a bonding layer, and the bonding portion is electrically connected to the electrical connection line via the bonding layer; the bonding layer has a first spreading width along a second direction perpendicular to the first direction on each bonding portion, which is greater than a second spreading width along the second direction at the interval between two adjacent bonding portions.

[0009] According to another embodiment of the present application, a photovoltaic assembly is provided, including at least one battery string.

[0010] According to the battery strings and photovoltaic modules provided in the above-mentioned embodiments of the present application, different portions of the bonding layer provided on the electrical connection line are configured to have different spread widths. The portion of the bonding layer located between the electrical connection line and the bonding portion is configured to have a first spread width, and the portion located between two adjacent bonding portions is configured to have a second spread width. A larger first spread width can provide a greater pull-out resistance between the electrical connection line and the bonding portion to maintain the conductivity and stability between the electrical connection line and the bonding portion. A smaller second spread width can isolate the bonding layer from the electrodes on both sides of the battery cell to prevent the occurrence of a short circuit or reduce damage to the electrodes on both sides. BRIEF DESCRIPTION OF THE 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, and are not limitations to the present application.

[0012] Figure 1 A schematic top view of a cell string formed by back-contact solar cells provided in an embodiment of the present application;

[0013] Figure 2 for Figure 1 A schematic diagram of a partial structure of a battery string of the embodiment shown;

[0014] Figure 3A for Figure 2 A partial cross-sectional view taken along line A1-A2 of the embodiment shown;

[0015] Figure 3B for Figure 2 A partial cross-sectional view taken along line B1-B2 of the embodiment shown;

[0016] Figure 4 A schematic top view of a cell string formed by back-contact solar cells according to another embodiment of the present application;

[0017] Figure 5 for Figure 4 A schematic diagram of a partial structure of a battery string of the embodiment shown;

[0018] Figure 6 for Figure 5 A partial cross-sectional view taken along line B1-B2 of the embodiment shown;

[0019] Figure 7 A partial cross-sectional view of a cross section of a battery string along a second direction provided in yet another embodiment of the present application;

[0020] Figure 8 A schematic top view of a cell string formed by bifacial solar cells provided in an embodiment of the present application;

[0021] Figure 9 for Figure 8 A schematic diagram of a partial structure of a battery string of the embodiment shown;

[0022] Figure 10A for Figure 9 A partial cross-sectional view taken along line A1-A2 of the embodiment shown;

[0023] Figure 10B for Figure 9 A partial cross-sectional view taken along line B1-B2 of the embodiment shown;

[0024] Figure 11 A schematic top view of a cell string formed by bifacial solar cells according to another embodiment of the present application;

[0025] Figure 12 for Figure 11 A schematic diagram of a partial structure of a battery string of the embodiment shown;

[0026] Figure 13 for Figure 12 A partial cross-sectional view taken along line B1-B2 of the embodiment shown;

[0027] Figure 14 is a partial cross-sectional schematic diagram of a solar cell before packaging according to an embodiment of the present application; and

[0028] Figure 15 FIG. 1 is a schematic partial cross-sectional view of a solar cell after packaging according to an embodiment of the present application.

[0029] Description of reference numerals:

[0030] 1-battery cell;

[0031] 2-Electrical connection wire;

[0032] 3- first electrode;

[0033] 4- second electrode;

[0034] 5-junction;

[0035] 51-first joint;

[0036] 52- second joint;

[0037] 6-connecting part;

[0038] 7- third electrode;

[0039] 8-bonding layer;

[0040] 81-Part I;

[0041] 82-Part II;

[0042] 9-frame; and

[0043] 91- protrusion;

[0044] 11- first adhesive film;

[0045] 12- second adhesive film;

[0046] 13-first adhesive film;

[0047] 14- second adhesive film;

[0048] 15-cover plate;

[0049] 16- back plate;

[0050] 21-copper matrix;

[0051] 22-Solder. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0053] In the detailed description that follows, for ease of explanation, numerous specific details are set forth to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. Furthermore, in the following description, descriptions of known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present application.

[0054] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0055] When expressions such as “at least one of A, B, and C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, and C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.). When expressions such as “at least one of A, B, or C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, or C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.).

[0056] References to the relative position between two components (e.g., layers or regions) herein, such as “above,” “upper,” or “above,” may refer to the two components being in direct contact, or may refer to the two components being in indirect contact. Similarly, references to the relative position between two components herein, such as “under,” “lower,” or “below,” may refer to the two components being in direct contact, or may refer to the two components being in indirect contact. For example, when one component (e.g., a layer or region) is referred to as being “on another component,” it may be directly on the other component, or there may be other components between the two. On the other hand, when a component is referred to as being “directly on another component,” there is no component between the two. In addition, when one component is referred to as being “on another component,” the two have a top-down relationship in a top-down direction, and the component may be above or below the other component, so that the top-down relationship depends on the orientation of the device.

[0057] In back-contact solar cells, the positive electrode (also known as the first electrode or first auxiliary grid) and the negative electrode (also known as the second electrode or second auxiliary grid) are both located on the back side of the cell. To achieve this, auxiliary grids of different polarities are placed on different doping regions of the cell. The auxiliary grids are configured into a multi-segment structure with gaps to accommodate electrical connection wires, or electrical connection wires and main grids, passing through the gaps to connect to the auxiliary grids of corresponding polarity to collect the current collected by the auxiliary grids. The electrical connection wires are then welded to the joints (e.g., pads) of different back-contact solar cells to connect the different back-contact solar cells in series, thus forming a cell string.

[0058] In bifacial solar cells, first and second electrodes are located on the first and second surfaces of the cell, respectively. A main grid is connected to a secondary grid of the same polarity to collect the current collected by the electrodes. Electrical wires are then soldered to the joints (e.g., pads) of different bifacial solar cells to connect them in series, forming a cell string.

[0059] Currently, the bonding layer (including but not limited to solder) used to connect electrical wires and pads is often applied point by point along the extension of the electrical wires using a welding gun or other welding equipment, based on the welding location. During welding, the battery cell will undergo some deformation. Therefore, subsequent processes such as layout and lamination are required to flatten the cell. Under the pressure, the bonding layer will spread outward.

[0060] Among them, the spreading width of the bonding layer along the gap formed by the auxiliary grid needs to be paid special attention. If the width is too small, it will affect the conductivity and reliability between the bonding part and the electrical connection line; if the width is too large, the bonding layer located in the gap formed by the auxiliary grid will contact the auxiliary grids on both sides, thereby affecting the auxiliary grids on both sides.

[0061] Therefore, based on the same inventive concept, how to provide a battery string and photovoltaic module that maintains the electrical connection and pull-out reliability of the electrical connection wires and the joints while avoiding connection with the auxiliary grids on both sides has become a technical problem that needs to be solved urgently.

[0062] According to an exemplary embodiment of the present application, the present application provides a battery string and a photovoltaic module, wherein the battery string includes:

[0063] A battery cell, wherein at least one surface of the battery cell has at least two joints spaced apart along a first direction; and

[0064] an electrical connection line extending along a first direction;

[0065] In which, a bonding layer is provided on the surface of the electrical connection line facing the battery cell, and the bonding part is electrically connected to the electrical connection line through the bonding layer; the bonding layer is located on each bonding part, and has a first spreading width along a second direction perpendicular to the first direction, which is greater than the second spreading width along the second direction at the interval between two adjacent bonding parts.

[0066] According to an embodiment of the present application, the type of solar cell may be a back contact solar cell, and the back contact solar cell includes but is not limited to any one of an interdigitated back contact solar cell (IBC), a hybrid BC (combined passivated BC), a low-temperature interdigitated back contact heterojunction solar cell (HBC), a tunneling oxide passivated contact back contact solar cell (TBC), and a polycrystalline silicon onoxide interdigitated back contact solar cell (POLO-IBC); it may also be a bifacial solar cell, for example, a bifacial heterojunction (Heterojunction with Intrinsic Thin-layer, abbreviated as HJT) cell.

[0067] Figure 1 A schematic top view of a cell string formed by back-contact solar cells provided in an embodiment of the present application.

[0068] Figure 2 for Figure 1 A schematic diagram of the partial structure of a battery string of the embodiment shown.

[0069] According to an exemplary embodiment of the present application, the present application provides a cell string formed by a back contact solar cell, with reference to Figure 1 、 Figure 2 As shown, it includes a battery cell 1 and an electrical connection line 2. The battery cell 1 has a first surface and a second surface relative to each other, and the second surface of the battery cell 1 has at least two bonding portions 5 spaced apart along a first direction. The electrical connection line 2 extends along the first direction, is bonded to the surface of the battery cell 1, and is electrically connected to the at least two bonding portions 5. The surface of the electrical connection line 2 facing the battery cell 1 is provided with a bonding layer 8, and the bonding portion 5 is electrically connected to the electrical connection line 2 through the bonding layer 8; the first spreading width of the bonding layer 8 between the electrical connection line 2 and the bonding portion 5 along the second direction is greater than the second spreading width between two adjacent bonding portions 5 along the second direction, and the first direction is orthogonal to the second direction.

[0070] That is, a first spreading width of the bonding layer 8 on each bonding portion 5 along a second direction perpendicular to the first direction is greater than a second spreading width along the second direction at a space between two adjacent bonding portions 5 .

[0071] In an exemplary embodiment, the battery cell 1 includes but is not limited to a substantially rectangular structure ( Figure 2 Only a part of the battery cell 1 is shown), including along the first direction (such as Figure 2 The first side extending in the up and down direction as shown in FIG. Figure 2 The first side may be used as the long side of the battery cell 1, and the corresponding second side may be used as the short side of the battery cell. It should be understood that the embodiments of the present application are not limited thereto.

[0072] For example, the joint portion 5 includes but is not limited to being configured as a substantially rectangular, polygonal, circular, elliptical, racetrack-shaped, or any other shape suitable for connecting to the electrical connection line 2 (i.e., soldering ribbon). For example, the joint portion 5 includes but is not limited to being a solder pad.

[0073] In an illustrative embodiment, Figures 1 to 2 As shown, a plurality of joints 5 ( Figure 2 Further, the plurality of joints 5 are arranged along the first direction (e.g. Figure 2 The plurality of joints 5 may be arranged at equal intervals along the first direction; or at least some of the joints 5 may have different intervals from the other joints 5 (for example, the joints 5 arranged in the middle of the battery cell 1 may be arranged at equal intervals, while the joints 5 located at the edge of the battery cell 1 may be arranged at different intervals from the adjacent joints 5).

[0074] Figure 3A for Figure 2 A partial cross-sectional view taken along line A1-A2 of the embodiment shown.

[0075] Figure 3B for Figure 2 A partial cross-sectional view taken along line B1-B2 of the illustrated embodiment.

[0076] In an illustrative embodiment, Figure 3A and Figure 3B As shown, the surface of the electrical connection wire 2 (ie, the welding ribbon) facing the battery cell 1 (ie, Figure 3A and Figure 3B The lower surface shown in FIG. 1 is provided with a bonding layer 8. In detail, the bonding layer 8 includes but is not limited to solder (such as solder and / or other bonding materials).

[0077] In an illustrative embodiment, Figure 3A and Figure 3B As shown, the bonding layer 8 includes a first portion 81 disposed between the electrical connection line 2 (i.e., the welding ribbon) and the bonding portion 5, and a second portion 82 disposed between the electrical connection line 2 (i.e., the welding ribbon) and the battery cell 1. In detail, the first portion 81 is disposed along the second direction (i.e., Figure 3A The first spread width (ie, d1 ) of the second portion 82 (ie, the left-right direction as shown) is configured to be greater than the second spread width (ie, d3 ) of the second portion 82 , ie, d1 > d3 .

[0078] In this embodiment, by configuring the first portion 81 and the second portion 82 of the bonding layer 8 to have different spread widths, the bonding layer 8 can be adapted to the spread width requirements at different locations on the cell 1. The first portion 81 serves as a solder joint connecting the electrical connection wire 2 (i.e., the soldering ribbon) to the bonding portion 5. The first spread width is configured to be greater than the second spread width. While providing good solderability, the larger spread area of the first portion 81 provides greater pull-out resistance for the electrical connection wire 2 (i.e., the soldering ribbon), thereby improving the electrical conductivity and stability between the electrical connection wire 2 (i.e., the soldering ribbon) and the bonding portion 5. The second portion 82, having a smaller second spread width, facilitates isolation between the electrical connection wire 2 and the electrodes of different polarities on the cell 1, thereby preventing short circuits.

[0079] According to the embodiments of the present application, Figure 3A and Figure 3B As shown, 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, it 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 listed.

[0080] In an illustrative embodiment, Figure 3A and Figure 3BAs shown, d3 / d1 includes but is not limited to being configured as 0.2 / 0.8 to 0.6 / 0.8. Further, the bonding layer 8 along the second direction (such as Figure 3A and Figure 3B The spread width (including the first spread width and the second spread width) of the bonding layer 8 (in the left and right directions shown) is positively correlated with the thickness of the bonding layer 8. That is, the thicker the bonding layer 8, the larger the spread width after bonding. Therefore, the thickness of the bonding layer 8 needs to be limited.

[0081] For example, for an electrical connection line 2 configured with a width of 0.3mm~0.6mm, the thickness of the bonding layer 8 before bonding includes but is not limited to being configured as 0.01mm~0.05mm; based on the above thickness of the bonding layer 8, the thickness of the first part 81 of the bonding layer 8 after bonding can be maintained at 0.005mm~0.03mm.

[0082] According to the embodiments of the present application, Figures 1 to 2 、 Figure 3A~Figure 3B As shown, the battery cell 1 also includes a plurality of first electrodes 3 and 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 alternately arranged in sequence along the first direction, and the first electrode 3 is connected to the joint 5 or the electrical connection line 2.

[0083] According to the embodiments of the present application, Figures 1 to 2 、 Figure 3B As shown, at least a portion of the second electrodes 4 is discontinuous in the second direction and a disconnection portion is formed at the discontinuous position. The electrical connection line 2 passes through the disconnection portion, and the joint portion 5 extends into a portion of the disconnection portion.

[0084] According to the embodiments of the present application, Figures 1 to 2 As shown, a portion of the disconnected portion forms a first gap, another portion of the disconnected portion forms a second gap, and the engaging portion 5 is disposed in the disconnected portion forming the first gap. The width of the first gap is configured to be greater than the width of the second gap.

[0085] In an illustrative embodiment, Figure 1 and Figure 2 As shown, the first electrode 3 (i.e., the auxiliary grid with the same polarity as the joint 5) and the second electrode 4 (i.e., the auxiliary grid with a different polarity from the joint 5) are arranged on the back side of the battery cell 1 (i.e., Figure 1 In detail, the plurality of first electrodes 3 and the plurality of second electrodes 4 are arranged along a first direction (such as Figure 2 In the vertical direction shown in the figure, the interdigitated structures are alternately arranged in sequence to form an interdigitated structure to adapt to the different doping regions (such as p+ doping region and n+ doping region) arranged in parallel and at intervals on the back side of the battery cell 1.

[0086] According to the embodiments of the present application, Figure 2 As shown, the battery string further includes a connecting portion 6 extending along the second direction, and the connecting portion 6 connects the joining portion 5 and a portion of the first electrode 3 .

[0087] In an illustrative embodiment, Figure 2 As shown, the distal end of the connecting portion 6 away from the joint 5 (ie Figure 2 The width of 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) is configured to be smaller than the width of the proximal end near the joint 5 (the right end of the connecting portion on the left side, and the left end of the connecting portion on the right side) (ie Figure 2 The distance between the upper end and the lower end of the connecting portion 6 shown).

[0088] For example, the connecting portion 6 may be configured as a generally triangular structure;

[0089] For example, the shape of the connection portion 6 is a triangle whose cross section gradually decreases from an end close to the joint portion 5 to an end away from the joint portion 5 .

[0090] For another example, the connecting portion 6 may be configured to have a substantially trapezoidal structure.

[0091] For example, the shape of the connecting portion 6 is a trapezoid whose cross section gradually decreases from an end close to the joint portion 5 to an end away from the joint portion 5 .

[0092] In such an embodiment, the proximal end of the connecting portion 6 is set wider, which increases the width of the connecting portion between the first electrode 3 and the joint 5. This can prevent the connecting portion between the first electrode 3 and the joint 5 from being melted, and can also prevent current concentration, which is beneficial to improving the current collection effect.

[0093] In an illustrative embodiment, Figure 1 and Figure 2 As shown, each second electrode 4 (ie, the auxiliary grid having a different polarity from the junction portion 5) has a second direction (eg Figure 2 In detail, a disconnection portion is formed between two adjacent electrode segments.

[0094] According to the embodiments of the present application, Figure 2 、 Figure 3B As shown, the battery string further includes a third electrode 7 extending along the first direction on the second surface, the third electrode 7 passing through part of the disconnected portion and connecting at least two adjacent joints 5. The portion of the joint layer 8 located between the third electrode 7 and the electrical connection line 2 is configured to have a second spreading width.

[0095] In an illustrative embodiment, Figure 2 As shown, the third electrode 7 (i.e., the main grid) is connected along the first direction (e.g., Figure 2A plurality of joints 5 are evenly spaced apart in the vertical direction shown in FIG. In detail, the joints 5 include but are not limited to a structure configured to be substantially strip-shaped.

[0096] In an illustrative embodiment, Figure 2 and Figure 3B As shown, the third electrode 7 (i.e., the main grid) is arranged along the first direction (e.g., Figure 2 Specifically, the third electrode 7 (i.e., the main grid) passes through the disconnected portion formed by the second electrode 4 of different polarity and connects to the first electrode 3 of the same polarity. Furthermore, a bonding layer 8 covers the third electrode 7 (i.e., the main grid).

[0097] In an illustrative embodiment, Figure 3A and Figure 3B As shown, the first spread width (i.e., d1) of the first portion 81 is configured to be smaller than the width (i.e., d2) of the joint portion 5, and the width (i.e., d3) of the second portion 82 is configured to be smaller than the width (i.e., d4) of the disconnection portion formed by the second electrode 4. That is, d2>d1, d4>d3, and d1>d3.

[0098] In an exemplary embodiment, the electrode segments of the second electrode 4 located on both sides of the joint 5 form a first gap, and the second electrodes 4 located on both sides of the third electrode 7 form a second gap. The width of the first gap (i.e., L1) is configured to be greater than the width of the joint 5, and the width of the second gap (i.e., L2) is configured to be greater than the width of the electrical connection line 2. Furthermore, the width of the first gap is configured to be greater than the width of the second gap (i.e., L1>L2).

[0099] In such an embodiment, the disconnect portion provided on the second electrode 4 is adapted to the width of the third electrode 7 and the joint portion 5 to configure gaps of different widths (i.e., a first gap and a second gap), which can more effectively maintain the isolation between the second electrode 4 and the third electrode 7 and / or the joint portion 5 of different polarities to avoid the occurrence of a short circuit.

[0100] In an illustrative embodiment, Figure 3A As shown, the width of the joint 5 (ie, d2) includes, but is not limited to, being configured to be 1.2 mm to 1.3 mm. Accordingly, the width of the third electrode 7 (ie, the main grid) includes, but is not limited to, being configured to be 50 μm to 90 μm.

[0101] Due to the precision limitation of the welding gun and / or other welding equipment, it is inevitable that the bonding layer 8 will be offset from the center line of the electrical connection line 2 (that is, in the orthographic projection in the thickness direction of the battery cell 1, the center line of the bonding layer 8 is offset from the center line of the electrical connection line 2 along the first direction), so that at least a portion of the bonding layer 8 contacts the passivation layer on the surface of the battery cell 1 (for example, the bonding layer 8 is offset from the center line of the electrical connection line 2 in the first direction). Figure 3AThe leftward offset shown causes the left end of the bonding layer 8 to be located on the passivation layer. The passivation layer comprises an oxide layer formed on the surface of the cell 1 to protect the surface of the cell 1 from corrosion and damage from the external environment. The passivation material forming the passivation layer includes, but is not limited to, Al2O3.

[0102] Based on the above-mentioned size configuration, the offset of the bonding layer 8 caused by the equipment accuracy can be compensated, that is, when the bonding layer 8 is offset relative to the center line of the electrical connection line 2 (that is, the welding strip), the bonding layer 8 will not contact the second electrode 4 in the offset direction.

[0103] Figure 4 A schematic top view of a cell string formed by back-contact solar cells provided in another embodiment of the present application shows a back-contact solar cell without a busbar.

[0104] Figure 5 for Figure 4 A schematic diagram of the partial structure of a battery string of the embodiment shown.

[0105] Figure 6 for Figure 5 A partial cross-sectional view taken along line B1-B2 of the illustrated embodiment.

[0106] In another exemplary embodiment, Figure 4-Figure 6 As shown, the first electrode 3 is directly connected to the electrical connection line 2, so that the current collected by the first electrode 3 is directly collected through the electrical connection line 2. This simplifies the screen design for printing the electrode and eliminates the need for the paste (such as silver) used to print the third electrode 7 (i.e., the main grid).

[0107] According to an embodiment of the present application, the bonding portion 5 includes 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 cell 1 , and the size of the first bonding portion 51 is larger than that of the second bonding portion 52 .

[0108] According to the embodiment of the present application, the area of the first bonding portion 51 is larger than the area of the second bonding portion 52. The first bonding portion 51 is located near the edge of the cell 1. The edge of the silicon wafer serves as the starting and ending points of welding and is subject to the greatest pull-out force. By setting the area of the first bonding portion 51 larger, a greater pull-out resistance is achieved between the electrical connection wire 2 and the first bonding portion 51, thereby maintaining the stability of the electrical connection wire 2 and the first bonding portion 51.

[0109] According to an embodiment of the present application, the width of the first joining portion 51 along the first direction is greater than the width of the second joining portion 52 along the first direction, and the length of the first joining portion 51 along the second direction is equal to or slightly less than the length of the second joining portion 52 along the second direction. The second joining portion 53 has a smaller width, which can ensure electrical interconnection with electrical connection lines at multiple locations and reduce the contact resistance between the joining portion and the electrical connection lines.

[0110] For example, reference Figure 4 As shown, the bonding portion 5 includes a first bonding portion (i.e., a large pad) 51 located at the edge of the battery cell and a second bonding portion (i.e., a small pad) 52 located inside the battery cell. The width of the second bonding portion 52 along the second direction is smaller than the width of the first bonding portion 51 along the second direction.

[0111] Figure 7 A partial cross-sectional view of a battery string provided along a second direction according to yet another embodiment of the present application.

[0112] According to the embodiments of the present application, Figure 7 As shown, the battery string also includes a frame 9, which is arranged on the portion of the battery cell 1 located outside the joint 5. A protrusion 91 is formed on the side of the frame 9 facing the joint 5, and the protrusion 91 is pressed against the first surface of the joint 5 facing away from the battery cell 1.

[0113] According to the embodiments of the present application, Figure 7 As shown, the distance between two protrusions 91 of the surrounding frame 9 facing each other along the second direction is greater than the width of the electrical connection line 2 .

[0114] According to the embodiments of the present application, Figure 7 As shown, the bonding layer (not shown in the figure) and the tin layer of the electrical connection line 2 are melted into one.

[0115] In an illustrative embodiment, Figure 7 As shown, the frame 9 is arranged on the battery cell 1 outside the joint 5 in response to the shape of the joint 5. In detail, the frame 9 is as follows: Figure 7 The upper portion shown in FIG. 1 is formed with a protruding portion 91 protruding toward one side of the joint portion 5 so that the surrounding frame 9 Figure 7 The cross section shown in FIG. 1 forms a cross section structure similar to an "L-shape". Further, the protrusion 91 presses against the first surface of the joint 5 (ie, Figure 7 The upper surface shown in FIG. 1 ) is formed so that the joint 5 is confined between the frame 9 and the battery cell 1. The frame 9 includes but is not limited to being made of aluminum.

[0116] In an exemplary embodiment, the surrounding frame 9 of the joint portion 5 adapted to be configured as a rectangle is also configured as a substantially rectangular frame structure. It should be understood that the embodiments of the present application are not limited thereto.

[0117] The surrounding frame 9 may also be configured as a frame structure having a shape different from the outer shape of the joint 5. For example, the surrounding frame 9 may be formed as a discontinuous structure that half surrounds or abuts against a portion of the edge of the joint 5.

[0118] Figure 8 A schematic top view of a cell string formed by bifacial solar cells provided in an embodiment of the present application.

[0119] Figure 9 for Figure 8 A schematic diagram of the partial structure of a battery string of the embodiment shown.

[0120] Figure 10A for Figure 9 A partial cross-sectional view taken along line A1-A2 of the embodiment shown.

[0121] Figure 10B for Figure 9 A partial cross-sectional view taken along line B1-B2 of the illustrated embodiment.

[0122] According to an exemplary embodiment of the present application, the present application provides a cell string formed by a bifacial solar cell, such as Figure 8 、 Figure 9 As shown, it includes a battery cell 1 and an electrical connection line 2. The battery cell 1 has a first surface and a second surface relative to each other, and the first surface and / or the second surface has at least two bonding portions 5 spaced apart along a first direction. The electrical connection line 2 extends along the first direction, is bonded to the surface of the battery cell 1, and is electrically connected to the at least two bonding portions 5. The surface of the electrical connection line 2 facing the battery cell 1 is provided with a bonding layer 8, and the bonding portion 5 is electrically connected to the electrical connection line 2 through the bonding layer 8; the bonding layer 8 is located between the electrical connection line 2 and the bonding portion 5, and has a first spreading width along a second direction perpendicular to the first direction, which is greater than the second spreading width along the second direction between two adjacent bonding portions 5.

[0123] According to the embodiments of the present application, Figure 10A 、 Figure 10B As shown, 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, it 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 listed.

[0124] According to an embodiment of the present application, the battery cell 1 also includes a plurality of first electrodes 3 extending along the second direction on the first surface, the first electrodes 3 being connected to the joining portion 5 or the electrical connection line 2; and a plurality of second electrodes 4 extending along the second direction on the second surface, wherein the second electrodes 4 are connected to the joining portion 5 or the electrical connection line 2.

[0125] According to the embodiments of the present application, Figure 8 、 Figure 9 As shown, the cell string formed by the bifacial solar cells also includes a third electrode 7 extending along the first direction and located on the first surface and / or the second surface of the cell 1, and the third electrode 7 connects at least two adjacent joints 5; the portion of the bonding layer 8 located between the third electrode 7 and the electrical connection line 2 is configured to have a second spreading width.

[0126] According to an embodiment of the present application, in a bifacial solar cell, the portion of the bonding layer located between the electrical connection line and the bonding portion is configured to have a first spread width, while the portion located between two adjacent bonding portions is configured to have a second spread width. The larger first spread width can provide a greater pull-out resistance between the electrical connection line and the bonding portion, thereby maintaining conductivity and stability between the electrical connection line and the bonding portion; the smaller second spread width can reduce the contact resistance between the electrical connection line and the electrodes on both sides, thereby reducing damage to the electrodes on both sides.

[0127] Figure 11 A schematic top view of a cell string formed by bifacial solar cells provided in another embodiment of the present application.

[0128] Figure 12 for Figure 11 A schematic diagram of the partial structure of a battery string of the embodiment shown.

[0129] Figure 13 for Figure 12 A partial cross-sectional view taken along line B1-B2 of the illustrated embodiment.

[0130] In another exemplary embodiment, Figure 11-13 As shown, the first electrode 3 and / or the second electrode 4 are directly connected to the electrical connection line 2, so that the current collected by the first electrode 3 and / or the second electrode 4 is directly collected through the electrical connection line 2. This simplifies the screen design for printing the electrodes and eliminates the need for the paste (e.g., silver) used to print the third electrode 7 (i.e., the main grid).

[0131] According to an embodiment of the present application, the battery string further includes at least one adhesive film, which is suitable for covering the electrical connection wires 2 and at least a portion of the battery cells 1. By covering the electrical connection wires 2 with the adhesive film, the electrical connection wires 2 are fixed to the battery cells 1.

[0132] Figure 14 FIG. 1 is a partial cross-sectional schematic diagram of a solar cell before packaging according to an embodiment of the present application.

[0133] Figure 15 FIG. 1 is a schematic partial cross-sectional view of a solar cell after packaging according to an embodiment of the present application.

[0134] like Figure 14As shown, electrical connection lines 2 are formed on the first and second surfaces of the cell 1, respectively. A first adhesive film 11 is applied to the electrical connection lines 2 on the first surface, and a second adhesive film 12 is applied to the electrical connection lines 2 on the second surface. A first adhesive film 13 is applied to the cover plate 15, and a second adhesive film 14 is applied to the back plate 16.

[0135] like Figure 14 、 Figure 15 As shown, the first adhesive film 11 and the first adhesive film 13 are laminated, and the second adhesive film 12 and the second adhesive film 14 are laminated, and are placed in a heating chamber for lamination. The electrical connection line 2 is composed of a copper substrate 21 and a solder 22. The solder 22 is melted in the heating chamber to interconnect the secondary grid on the surface of the battery cell 1 with the electrical connection line 2; the first adhesive film 11 and the first adhesive film 13 are bonded to connect the battery cell 1 and the cover plate 15, and the second adhesive film 12 and the second adhesive film 14 are bonded to connect the battery cell 1 and the back plate 16.

[0136] A photovoltaic assembly provided by the present application, not shown in the figures, includes at least one battery string.

[0137] In an illustrative embodiment (not shown), a photovoltaic module includes multiple cell strings. Specifically, the multiple cell strings are arranged in intervals. Furthermore, the multiple back-contact cells in each cell string are arranged in columns. Electrical connections interconnect the cells within the same cell string.

[0138] The use of ordinal numbers such as "first," "second," and "third" in the specification and claims to modify corresponding elements does not in itself mean that the elements have any ordinal number, nor does it represent the order of one element relative to another or the order in the manufacturing method. The use of such ordinal numbers is only used to clearly distinguish one element with a certain name from another element with the same name.

[0139] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of this application. It should be understood that the above is only a specific embodiment of this application and is not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this 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; The surface of the electrical connection line (2) facing the battery cell (1) is provided with a bonding layer (8), and the bonding portion (5) is electrically connected to the electrical connection line (2) via the bonding layer (8); The first spreading width of the bonding layer (8) on each bonding portion (5) along a second direction perpendicular to the first direction is greater than the second spreading width along the second direction at the interval between two adjacent bonding portions (5); Wherein, along the first direction, there is no other electrode connection between two adjacent joint portions (5); At least one adhesive film covers the electrical connection line (2) and at least a portion of the battery cell (1).

2. The battery string according to claim 1, characterized in that: The ratio of the second spreading width to the first spreading 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 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 disconnection 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 1, characterized in that: The battery cell (1) has a first surface and a second surface that are 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 portion (5) or the electrical connection line (2).

6. The battery string according to claim 1, characterized in that: The joining portion (5) comprises a first joining portion (51) and a second joining portion (52), Wherein, along the first direction, the first joining portion (51) is distributed close to the edge of the battery cell (1), and the size of the first joining portion (51) is larger than the size of the second joining portion (52).

7. A photovoltaic module, characterized in that: The method comprises at least one battery string according to any one of claims 1 to 6.

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