Back contact battery and photovoltaic module

Abstract

The present application provides a back contact battery and a photovoltaic module. The back contact battery comprises: a battery body having a first surface and a second surface which are opposite to each other; first electrodes and second electrodes, which are provided on the first surface of the battery body, wherein the first electrodes and the second electrodes are sequentially and alternately arranged at intervals in a first direction and extend in a second direction; and a connecting conductor which is provided on the first surface and extends in the first direction, wherein the connecting conductor is connected to one of each first electrode and each second electrode, an insulating block is provided between the connecting conductor and the other one of the first electrode and the second electrode, the connecting conductor comprises first portions provided on the insulating blocks and second portions provided between two adjacent insulating blocks, and a first width of each first portion in the second direction is smaller than a second width of each second portion in the second direction, thereby improving the reliability of connection between the connecting conductor and the electrodes.

Description

Back contact cell and photovoltaic module TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular to a back contact cell and a photovoltaic module. BACKGROUND

[0002] In the back contact cell, the positive auxiliary grid and the negative auxiliary grid are respectively arranged on different doped regions of the back surface of the cell body, and then the current generated by the cell body is collected by connecting with the main grid of the same polarity. In addition to being connected with the auxiliary grid, the main grid also needs to be connected with the external electrical connector to form a cell string by connecting a plurality of back contact cells in series. Therefore, the connection strength between the main grid and the auxiliary grid and the connection strength between the main grid and the electrical connector are of great significance to the reliability of the back contact cell and the photovoltaic module formed by the back contact cell.

[0003] Since the main grid and the auxiliary grid are arranged in different directions, the main grid will cross the auxiliary grid of different polarity while being connected with the auxiliary grid of the same polarity. In order to prevent the short circuit caused by the main grid connecting the auxiliary grid of different polarity, an insulating block needs to be arranged between the main grid and the auxiliary grid of different polarity. Generally, the connection strength between the main grid and the insulating block is weaker than the connection strength between the main grid and the cell body. Therefore, the reliability of the connection between the main grid and the auxiliary grid is limited. SUMMARY

[0004] To solve at least one of the above and other technical problems in the prior art, the present application provides a back contact cell and a photovoltaic module, which are beneficial to improving the reliability of the connection between the connecting conductor and the electrode and the external electrical connector.

[0005] Embodiments of the present application provide a back contact cell, comprising:

[0006] a cell body having opposite first and second surfaces;

[0007] a first electrode and a second electrode arranged on the first surface of the cell body, the first electrode and the second electrode being arranged alternately and spaced apart in a first direction and extending in a second direction perpendicular to the first direction;

[0008] a connecting conductor arranged on the first surface and extending in the first direction, the connecting conductor being connected with one of the first electrode and the second electrode and having an insulating block between the connecting conductor and the other electrode;

[0009] wherein the connecting conductor comprises a first part arranged on the insulating block and a second part arranged between two adjacent insulating blocks in the first direction, and a first width of the first part in the second direction is smaller than a second width of the second part in the second direction.

[0010] In the above-mentioned embodiment, the wider second part is used to connect the first electrode or the second electrode, so that the part of the connecting conductor connecting the electrode in the second direction is wider, and has a larger bonding area with the battery body, thereby improving the connection strength between the connecting conductor and the battery body, and effectively improving the contact area between the connecting conductor and the electrode, reducing the contact resistance, and further improving the connection reliability between the connecting conductor and the electrode.

[0011] In some illustrative embodiments, the second part protrudes from the first part at both ends in the second direction, and the width of the part of the second part protruding from the first part at each end in the second direction is between 80-250 microns.

[0012] In some illustrative embodiments, the first width is between 0.5-1.5 mm.

[0013] In the above-mentioned embodiment, based on the size design of the connecting conductor, the contact area between the connecting conductor and the corresponding electrode can be ensured while effectively controlling the amount of material of the connecting conductor, thereby reducing the contact resistance.

[0014] In some illustrative embodiments, the battery body has a first edge extending in the second direction.

[0015] The connecting conductor includes a first connecting conductor connected to the first electrode and provided with the insulating block between the first connecting conductor and the second electrode, and the second part of the first connecting conductor closest to the first edge is arranged between two adjacent insulating blocks in the first direction.

[0016] In the above-mentioned embodiment, based on the arrangement of the first electrode on the battery body, the first connecting conductor is correspondingly configured to collect the current collected by the first electrode. The second part between the insulating blocks is wider than the first part, which is beneficial to disperse the stress between the second part and the first surface. In this way, the connection between the connecting conductor and the electrode is more firm, and it is also beneficial to prevent the connecting conductor from warping.

[0017] In some illustrative embodiments, the connecting conductor includes a second connecting conductor connected to the second electrode and provided with the insulating block between the second connecting conductor and the first electrode.

[0018] The second part of the second connecting conductor closest to the first edge is arranged between the first edge and the insulating block adjacent to the first edge.

[0019] With the above-mentioned embodiments, based on the arrangement of the second electrode on the battery body, the second connecting conductor corresponding to the second electrode is configured to collect the current collected by the second electrode, the second part between the insulating blocks is wider than the first part, which is beneficial to disperse the stress between the second part and the second surface, while increasing the contact area of the connecting conductor and the second electrode. Further, it not only makes the connection between the connecting conductor and the electrode more firm, but also helps to prevent the connecting conductor from warping, and the second part of the second connecting conductor between the first edge and the insulating block is also beneficial to shorten the transmission path of the carrier along the second direction, so as to more fully collect the edge current of the battery body.

[0020] In some illustrative embodiments, the first spacing between the end of the first connecting conductor adjacent to the first edge and the first edge is greater than the second spacing between the end of the second connecting conductor adjacent to the first edge and the first edge.

[0021] In some illustrative embodiments, the first spacing is between 1-3 mm.

[0022] In some illustrative embodiments, the second spacing is between 0.5-1.5 mm.

[0023] With the above-mentioned embodiments, for the first connecting conductor configured with the first spacing, both ends of the first connecting conductor along the first direction are located between the second electrode closest to the first edge and the first electrode next closest to the first edge. In this way, the first connecting conductor is extended to the insulating block located at the edge of the battery body, thereby maintaining the connection reliability of the first connecting conductor and the first electrode located at the edge of the battery body, and saving the material used for printing the first connecting conductor. The second connecting conductor configured with the second spacing can effectively collect the edge current of the battery body.

[0024] In some illustrative embodiments, the ratio of the thickness of the second part to the thickness of the first part is between 4-10.

[0025] With the above-mentioned embodiments, the thickness of the first part and the thickness of the second part are related, if too thin, it is not conducive to the transmission of current, and if too thick, it leads to waste of material.

[0026] In some illustrative embodiments, the thickness of the second part is greater than or equal to 25 microns.

[0027] With the above-mentioned embodiments, the second part is set to be thicker, which is beneficial to maintain the reliability of the electrical connection with the external electrical connector in the welded state, reduce the risk of poor welding, and under the condition of constant width, it can also increase the cross-sectional area of the connecting conductor to reduce the resistance of the connecting conductor.

[0028] In some illustrative embodiments, the first portion has a thickness between 5 microns and 15 microns.

[0029] In the above-mentioned embodiments, when the thickness of the second portion is greater than or equal to 25 microns, the first portion should be set to an appropriate thickness. If the thickness is set too thin, such as corresponding to the upper limit of the thickness ratio of 10, it is not conducive to the current transmission of the two adjacent fine grids. If the thickness is set too thick, such as corresponding to the lower limit of the thickness ratio of 4, it not only wastes the material of the connecting conductor, but also has a small improvement in electrical conduction, and can cause the connecting conductor to extend in the width direction during printing, thereby causing a short circuit with the other opposite fine grid.

[0030] In some illustrative embodiments, the first portion includes a first sub-portion that coincides with the projection of the connected first electrode or second electrode in the orthographic projection of the first surface, and a second sub-portion other than the first sub-portion.

[0031] In some illustrative embodiments, in a third direction orthogonal to both the first direction and the second direction, the top surface of the first portion protrudes from the top surface of the second portion.

[0032] In the above-mentioned embodiments, because the surface of the insulating block is smooth, the first portion formed on the insulating block is not only thinner than the second portion, but also is not easy to form an effective connection with the insulating block. Therefore, the second portion is the main connection point for effectively connecting the connecting conductor and the electrical connector. On this basis, the first portion is set to be higher than the second portion in the third direction, which not only saves materials, but also ensures that the second portion can form a better electrical connection, and at the same time ensures that the first portion can form a connecting portion connecting the adjacent two second portions to prevent disconnection of the grid.

[0033] In some illustrative embodiments, the material of the connecting conductor includes aluminum, copper, silver-coated copper, or silver-copper alloy.

[0034] In the above-mentioned embodiments, the connecting conductor made of aluminum, copper, silver-coated copper, or silver-copper alloy reduces the amount of silver paste used, not only reducing the corresponding process cost, but also taking into account the high electrical conductivity and corrosion resistance of the connecting conductor.

[0035] In some illustrative embodiments, the connecting conductor is arranged at the edge of at least one of the opposite two first edges close to the battery body.

[0036] That is, only the connecting conductor at the end is retained, and the connecting conductor is not arranged at the middle without the main grid structure, so as to realize the reliability of the solder strip connection at the end, while reducing the amount of material of the connecting conductor.

[0037] In some illustrative embodiments, a surface of the first portion facing away from the battery body has a first average roughness, and a surface of the second portion facing away from the battery body has a second average roughness, wherein the first average roughness is less than the second average roughness.

[0038] In some illustrative embodiments, the second average roughness is greater than or equal to 5 microns.

[0039] In some illustrative embodiments, the first average roughness is less than 10 microns.

[0040] In some illustrative embodiments, the surface of the first portion and the surface of the second portion facing away from the battery body are both formed with non-uniform protrusions, and a maximum protrusion of the second portion has a height perpendicular to the first surface that is greater than or equal to 8 microns.

[0041] In some illustrative embodiments, in the first direction, the first electrode has a width of 30 microns to 100 microns, and / or the second electrode has a width of 30 microns to 100 microns.

[0042] In some illustrative embodiments, in the first direction, the first electrode has a width of 300 microns to 600 microns, and / or the second electrode has a width of 300 microns to 600 microns.

[0043] In some illustrative embodiments, a portion of the battery body between adjacent first electrodes and second electrodes forms an isolation region, and the insulating block extends to the isolation region, or the insulating block covers the isolation region and extends to the second electrode or the first electrode.

[0044] In some illustrative embodiments, the back contact battery further comprises a plurality of thickened segments arranged at intervals in the first direction, the thickened segments being connected to the first electrode or the second electrode to which the second portion is connected, and the thickened segments having a width in the first direction that is greater than the width of the first electrode or the second electrode to which the thickened segments are connected.

[0045] In some illustrative embodiments, the connecting conductor further comprises a bonding pad arranged on at least one insulating block, and the bonding pad has a width in the second direction that is greater than the second width of the second portion.

[0046] Embodiments of the present application also provide a photovoltaic module comprising a back contact battery and an electrical connector, the electrical connector electrically connecting the connecting conductors of at least two of the above-described back contact batteries.

[0047] In the above-mentioned embodiments, the single electrical connector connects the connection conductor of one polarity of one back contact cell and simultaneously connects the connection conductor of the other polarity of the adjacent other back contact cell, so that the plurality of back contact cells are connected in series to form a cell string.

[0048] In some illustrative embodiments, a plurality of joints are arranged between the electrical connector and the connection conductor in the first direction.

[0049] In the above-mentioned embodiments, the second part of the connection conductor serves as the main joint with the first electrode or the second electrode and the electrical connector. The joint arranged on the second part has a larger joint area, so that the connection conductor and the electrical connector are effectively and firmly connected.

[0050] In some illustrative embodiments, the number of joints arranged on the same connection conductor is between 15 and 24.

[0051] In the above-mentioned embodiments, the number of joints arranged on the same connection conductor is between 15 and 24.

[0052] In some illustrative embodiments, a plurality of joints are arranged between the electrical connector and the connection conductor in the first direction, and the joints are arranged on the joint pads of the connection conductor.

[0053] In some illustrative embodiments, the third distance between the end of the electrical connector located in the cell body of the back contact cell and the first edge of the cell body adjacent to the end is between 1 and 5 millimeters.

[0054] In the above-mentioned embodiments, the third distance between the end of the electrical connector and the edge of the cell body prevents the cell body from being cracked due to the end of the electrical connector being too close to the edge of the cell body. BRIEF DESCRIPTION OF DRAWINGS

[0055] FIG. 1 is a schematic view of a top view of a back contact cell according to an illustrative embodiment of the present application;

[0056] FIG. 2 is a partial enlarged view of part A of the illustrative embodiment shown in FIG. 1;

[0057] FIG. 3 is a schematic view of a connection conductor according to an illustrative embodiment;

[0058] FIG. 4 is a schematic view of a connection conductor according to another illustrative embodiment;

[0059] FIG. 5 is a schematic view of a connection conductor according to yet another illustrative embodiment;

[0060] Fig. 6 is a schematic view of a thickened section provided when using the connection conductor shown in Fig. 4;

[0061] Fig. 7 is a partial sectional view of a B1-B2 cross section of the schematic embodiment shown in Fig. 1;

[0062] Fig. 8 is a schematic view of a connection conductor of a further schematic embodiment;

[0063] Fig. 9 is a schematic view of a top view of a photovoltaic module according to a schematic embodiment of the present application;

[0064] Fig. 10 is a partial sectional view of a cross section of the schematic embodiment shown in Fig. 9 in a first direction;

[0065] Fig. 11 is a partial sectional view of a cross section of a further schematic embodiment of the photovoltaic module shown in Fig. 9 in a first direction;

[0066] Fig. 12 is a schematic view of a top view of a back contact cell according to a schematic embodiment of the present application.

[0067] In the drawings, the following reference signs have the following meanings: 1 cell body; 2 first electrode; 3 second electrode; 4 connection conductor; 41 first connection conductor; 42 second connection conductor; 43 second portion; 44 first portion; 45 protrusion; 46 recessed section; 5 insulation block; 6 joint; 7 electrical connection; 8 air gap; 9 thickened section; 10 joint pad. DETAILED DESCRIPTION

[0068] 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.

[0069] The terms used herein are only used to describe specific embodiments, and are not intended to limit the present application. The terms "comprise", "include" and the like used herein indicate the presence of the stated features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0070] All terms used herein, including technical and scientific terms, have the meanings commonly understood by a person skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted to have meanings consistent with the context of the present specification, and should not be interpreted in an idealized or overly formal manner.

[0071] In the case of using expressions such as "at least one of A, B, and C", it should generally be understood that such expressions are used to prevent only cases where nothing is selected, that is, cases where only A alone, only B alone, or only C alone is selected, and not cases where both A and B or A and C are selected or both B and C are selected or both A and C are selected or both A and B and C are selected.

[0072] The different doped regions of the back surface of the back contact cell (i.e. BC cell) are alternately arranged in sequence, and the sub-grids arranged on the different doped regions are also alternately arranged and have different conductive types. In order to collect the current collected by the sub-grids, a busbar (i.e. Busbar) intersecting with the sub-grids is arranged on some back contact cells. The busbar arranged on the busbar needs to be connected with the sub-grids of the same polarity and needs to cross the sub-grids of different polarities. Therefore, the busbar needs to be electrically isolated from the sub-grids of different polarities.

[0073] Currently, the electrical isolation of the busbar from the sub-grids of different polarities is mainly achieved in two ways. One is to arrange the sub-grids in a discontinuous structure so that the busbar passes through the disconnected part formed by the sub-grids of different polarities. In this way, the busbar is connected to the surface of the sub-grids and the cell body. The other is to arrange the sub-grids in a continuous structure and arrange an insulating block between the part where the busbar overlaps with the sub-grids of different polarities. In this way, the busbar is connected to the sub-grids and the insulating block.

[0074] The latter way can more effectively avoid the electrical contact between the busbar and the sub-grids of different polarities, which is beneficial to reducing the short-circuit current and the leakage current. However, based on the material characteristics of the insulating block (such as insulating glue, silicon oxide, silicon nitride, or other materials), the surface of the insulating block is smooth, and the middle part is more protruding than the two sides. In this way, it is not conducive to form an effective connection with the part of the busbar located on the insulating block, and the reliability of the connection between the busbar and the sub-grids is lower than that of the former way. Moreover, the part of the busbar located on the insulating block also forms a generally arched structure with the shape of the insulating block, which is also not conducive to form an effective connection with the external interconnection strip.

[0075] Therefore, how to provide a back contact cell and a photovoltaic module that are conducive to effectively connecting the busbar with the sub-grids and the busbar with the external interconnection strip has become a technical problem to be solved.

[0076] Figure 1 is a schematic diagram of a top view of a back contact cell according to an illustrative embodiment of the present application. Figure 2 is a partial enlarged view of portion A of the illustrative embodiment shown in Figure 1.

[0077] According to the back contact cell provided by the present application, as shown in Figures 1 and 2, the back contact cell of the present application can be a conventional IBC cell (interdigitated back contact cell), a TBC cell (TOPCon back contact cell), an HBC cell (heterojunction back contact cell), or a hybrid back contact cell (i.e., the PN passivation is different passivation materials, such as a combination of polycrystalline silicon passivation and amorphous / microcrystalline passivation).

[0078] The above-mentioned back contact cell includes a cell body 1, which at least includes a substrate and a doped layer on the substrate, wherein the substrate is rectangular or square in structure, and the length of the first side (the long side as shown in Figure 1) or the second side (the short side as shown in Figure 1) is between 182-240 mm, preferably (182±2)*(191±2) mm, (182±2)*(210±2) mm, (210±2)*(210±2) mm.

[0079] The cell body 1 of the above-mentioned IBC cell (interdigitated back contact cell) includes first and second doped semiconductor portions arranged on the substrate in the first direction to form an interdigitated doped portion structure. One of the first and second doped semiconductor portions is n-type doped, and the other is p-type doped. The first and second doped semiconductor portions are respectively provided with spaced-apart electrode structures.

[0080] The cell body 1 of the above-mentioned TBC cell (TOPCon back contact cell) includes a tunneling oxide layer provided on the substrate, and first and second doped semiconductor portions formed by a doped polysilicon layer. The TOPCon structure formed by the stacked tunneling oxide layer and doped polysilicon layer can provide higher carrier lifetime and lower surface recombination than the IBC cell, which is beneficial to improving the photoelectric conversion efficiency of the TBC cell.

[0081] The cell body 1 of the above-mentioned HBC cell (heterojunction back contact cell) includes an n-type doped layer and a p-type doped layer stacked on the substrate to form a heterojunction structure. The n-type doped layer includes but is not limited to microcrystalline silicon or amorphous silicon (to provide electrons), and the p-type doped layer can also be microcrystalline silicon or amorphous silicon (e.g., boron as a dopant to provide holes). The HBC cell helps to improve the carrier lifetime and reduce surface recombination. Further, a transparent conductive oxide layer (i.e., TCO) can be provided between the surface of the n-type doped layer and the p-type doped layer and the electrode, which is beneficial to collecting the carriers in the doped region and also has an anti-reflection effect.

[0082] The cell body 1 of the hybrid back contact cell can adopt a layer structure similar to that of an IBC cell or a TBC cell, and on the basis thereof, a corresponding passivation layer structure, such as a combination of at least two of polysilicon passivation, amorphous silicon passivation, and microcrystalline silicon passivation, is configured.

[0083] Based on any one of the above embodiments, as shown in FIGS. 1 and 2, the back contact cell further includes a first electrode 2, a second electrode 3, and a connecting conductor 4 disposed on a first surface of the cell body 1 (such as the back surface of the cell body 1, i.e., the surface facing the viewing angle in FIG. 1, and the corresponding second surface is the light receiving surface). The first electrode 2 and the second electrode 3 are alternately and spacedly disposed in a first direction (such as the up-down direction in FIG. 1) and extend in a second direction (such as the left-right direction in FIG. 1). The first electrode 2 and the second electrode 3 can also be called fine grids, current collecting grid lines, sub-grids, etc. The first electrode 2 and the second electrode 3 have different polarities and are used to extract majority carriers or minority carriers of different doped regions, respectively. The connecting conductor 4 is disposed on the first surface and extends in the first direction (such as the up-down direction in FIG. 1). The connecting conductor 4 is connected to one of the first electrode 2 and the second electrode 3 and is provided with an insulating block 5 between the other one.

[0084] The connecting conductor 4 (which can be called a main grid in some cases and is used to collect current collected by the first electrode 2 or the second electrode 3) includes a first portion 44 disposed on the insulating block 5 and a second portion 43 disposed between two adjacent insulating blocks 5 in the first direction. The first portion 44 has a first width in the second direction that is smaller than a second width of the second portion 43 in the second direction.

[0085] The plurality of insulating blocks 5 are discretely distributed on the first electrode 2 or the third electrode 3.

[0086] In such an embodiment, the second portion 43, which is wider than the first portion 44, is used to connect the first electrode 2 or the second electrode 3. In this way, the part of the connecting conductor 4 that connects the electrode (i.e., the first electrode 2 or the second electrode 3) in the second direction is wider than the part that connects the insulating block 5 and has a larger bonding area with the cell body 1. This can effectively improve the connection strength between the connecting conductor 4 and the cell body, effectively improve the contact area between the connecting conductor 4 and the electrode, reduce the contact resistance, and further improve the connection reliability between the connecting conductor 4 and the electrode.

[0087] The back contact cell illustrated in the present application can also be a cell structure with no main grid (i.e. 0BB). In detail, the first electrode 2 and the second electrode 3 (may also be called fine grid, current collecting grid line, auxiliary grid, etc.) of the first surface of the cell body 1, which have different polarities and are used to extract the majority carriers or minority carriers of different doped regions, are directly connected to the external electrical connecting member 7 (may also be called solder strip or interconnection strip, which is used to connect at least two back contact cells in series) without the main grid. At this time, the connecting conductor 4 can be regarded as the joint 6 of the solder strip or as the main grid structure connecting the first electrode 2 or the second electrode 3.

[0088] On this basis, the connecting conductor 4 is arranged between the electrode (the first electrode 2 or the second electrode 3) and the electrical connecting member 7, which can be used as a joint (may be solder, solder paste, such as solder, which is used to solder the auxiliary grid and the solder strip; or can be a conductive adhesive layer, such as conductive silver paste, conductive glue, etc., which is used to conductively connect the auxiliary grid and the solder strip), so as to form a good soldering relationship between the electrode (i.e. the first electrode 2 or the second electrode 3) and the electrical connecting member 7.

[0089] Further, in this embodiment, the connecting conductor 4 is pre-arranged at a specific position of the cell body 1, and further, in the process of soldering the electrode and the electrical connecting member, the electrical connecting member has a joint, which melts and is combined with the connecting conductor 4 and forms an intermetallic compound (i.e. IMC).

[0090] In an illustrative embodiment, as shown in FIG. 1, the insulating block 5 includes, but is not limited to, an insulating small block configured as a substantially rectangular shape. In detail, the width of the insulating small block in the second direction should be configured to be greater than the width of the connecting conductor 4 (should be greater than the second width), so that the part of the connecting conductor 4 that overlaps the first electrode 2 in the orthographic projection direction of the cell body 1 is completely covered, so as to electrically isolate the connecting conductor 4 and the first electrode 2. Wherein, the insulating block 5 can be made of inorganic materials, such as silicon oxide, silicon nitride, etc., or can be made of organic materials, such as insulating glue, etc. The thickness of the insulating block 5 is not greater than 60 μm, for example, it can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, etc. The thickness should not be too large, so as to prevent the first part 44 from being too low, causing poor soldering, or requiring more connecting conductor material to offset the height difference; and generally, the thickness of the insulating block 5 should be greater than or equal to twice the thickness of the first electrode or the second electrode, so as to ensure sufficient insulation performance.

[0091] In an illustrative embodiment, as shown in FIG. 1, the first electrode 2 is provided with a plurality of insulating small blocks (i.e. insulating blocks 5). In detail, the plurality of insulating small blocks on each first electrode 2 are arranged at intervals along the first direction (such as the up-down direction shown in FIG. 1).

[0092] In an exemplary embodiment, the first electrode 2 is disposed on the n-type doped region, and the second electrode 3 is disposed on the p-type doped region, for example, in a case where the cell body 1 is based on n-type silicon. The first electrode 2 serves as the positive electrode of the back contact cell, and the second electrode 3 serves as the negative electrode of the back contact cell, corresponding to the respective doped regions. Similarly, the first electrode 2 can be disposed on the p-type doped region to serve as the negative electrode, and the second electrode 3 can be disposed on the n-type doped region to serve as the positive electrode.

[0093] According to an embodiment of the present application, as shown in FIG. 1, the cell body 1 includes two opposite first edges (long edges, i.e., the upper edge and the lower edge, as shown in FIG. 1) and two opposite second edges (short edges, i.e., the left edge and the right edge, as shown in FIG. 1). The connecting conductor 4 includes a first connecting conductor 41 connected to the first electrode 2 and disposed with the second electrode 3 by an insulating block 5. The second part 43 of the first connecting conductor 41 closest to the first edge is formed between two insulating blocks 5 adjacent in the first direction.

[0094] According to an embodiment of the present application, as shown in FIG. 1, the connecting conductor 4 includes a second connecting conductor 42 connected to the second electrode 3 and disposed with the first electrode 2 by an insulating block 5. The cell body 1 has a first edge extending in the second direction, and the second part 43 of the second connecting conductor 42 closest to the first edge is formed between the first edge and the insulating block 5 adjacent to the first edge.

[0095] In an exemplary embodiment, as shown in FIG. 1, the electrodes closest to the two first edges are both the second electrode 3. Further, the second part 43 of the second connecting conductor 42 closest to the first edge is located between the first edge and the insulating block 5 adjacent to the first edge, and the middle part 43 of the second connecting conductor 42 is located between two insulating blocks adjacent in the first direction (i.e., the up-down direction, as shown in FIG. 1). Correspondingly, the second part 43 of the first connecting conductor 41 is located between two insulating blocks adjacent in the first direction.

[0096] In such an embodiment, based on the arrangement of the first electrode 2 and the second electrode 3 on the battery body 1, the corresponding configuration of the connecting conductor 4 (including the first connecting conductor 41 and the second connecting conductor 42) is to collect the current collected by the first electrode 2 or the second electrode 3, respectively. The second part 43 of the connecting conductor 4 has a width in the second direction that is wider than the width of the first part 44 in the second direction, so as to form a larger cross-sectional area, which is conducive to reducing the series resistance between the electrodes and correspondingly improving the fill factor and output power of the back contact battery. Moreover, since the second part 43 of the connecting conductor 4 connected to the electrode occupies a larger area in the first surface than the first part 44, it is also conducive to dispersing the stress between the second part 43 and the first surface, while increasing the contact area of the connecting conductor 4 and the electrode. Further, not only does it make the connection between the connecting conductor 4 and the electrode more secure, but it also helps to prevent the connecting conductor 4 from warping. Moreover, the second part 43 of the second connecting conductor 42 between the first edge and the insulating block 5 is also conducive to shortening the transmission path of the carriers in the second direction, so as to more fully collect the edge current of the battery body.

[0097] According to an embodiment of the present application, as shown in FIG. 1, the first spacing S2 between the end of the first connecting conductor 41 adjacent to the first edge and the first edge is greater than the second spacing S1 between the end of the second connecting conductor 42 adjacent to the first edge and the first edge.

[0098] According to an embodiment of the present application, as shown in FIG. 1, the first spacing S2 is between 1-3 millimeters.

[0099] According to an embodiment of the present application, as shown in FIG. 1, the second spacing S1 is between 0.5-1.5 millimeters.

[0100] In such an embodiment, in the orthogonal projection along the thickness direction (i.e., the third direction described below) of the battery body 1, both ends of the first connecting conductor 41 in the first direction (such as the upper end and the lower end shown in FIG. 1) are located between the second electrode 3 closest to the first edge and the first electrode 2 next closest to the first edge, i.e., the end of the first connecting conductor 41 extends to the insulating block 5 closest to the first edge, but does not exceed the second electrode 3 covered by the insulating block 5 closest to the first edge. In this way, the first connecting conductor 41 is extended to the insulating block 5 located at the edge of the battery body 1 to maintain the connection reliability of the first connecting conductor 41 and the first electrode 2 located at the edge of the battery body 1, while saving the material used to print the first connecting conductor 41. The second connecting conductor 42 with the above-mentioned second spacing adaptively shortens the transmission distance of the carriers in the first direction and the second direction, which can effectively collect the edge current of the battery body, especially when the second electrode 3 is a negative electrode, the second connecting conductor 42 can reduce the surface recombination of minority carriers, thereby effectively collecting the minority carriers.

[0101] According to an embodiment of the present application, as shown in FIG. 2, the second part 43 protrudes from the first part 44 at both ends in the second direction, and the width W3 of the part of each end of the second part 43 protruding from the first part 44 in the second direction is between 80-250 microns.

[0102] According to an embodiment of the present application, as shown in FIG. 2, the first width is between 0.5-1.5 millimeters.

[0103] In an illustrative embodiment, as shown in FIGS. 1 and 2, the connecting conductor 4 can be considered to have a main body part (forming a substantially rectangular structure) extending in the first direction, and a plurality of protruding parts (i.e. the semicircular or semi-elliptical parts shown in FIG. 2) protruding to both sides in the second direction (i.e. the left-right direction shown in FIG. 1) are uniformly arranged on the main body part in the first direction (i.e. the up-down direction shown in FIG. 1). Here, the first width (i.e. W1 shown in FIG. 2) of the first part 44 can be considered to be the width of the main body part, and the second width (i.e. W2 shown in FIG. 2) of the second part 43 can be considered to be the sum of the width (i.e. W3 shown in FIG. 2) of the two protruding parts and the width of the main body part (i.e. W2=W1+2×W3). In addition, in other embodiments, the widths of the left and right protruding parts in the second direction can be different.

[0104] In an illustrative embodiment, as shown in FIG. 2, the first width of the first part 44 includes but is not limited to being configured to be 0.5-1.5 millimeters (i.e. W1=0.5mm-1.5mm). Correspondingly, the width of the protruding part includes but is not limited to being configured to be 80-250 microns (i.e. W3=80μm-250μm), i.e. the second width of the second part 43 includes but is not limited to being configured to be 0.66-2.0 millimeters (i.e. W2=0.66mm-2.0mm). In a preferred embodiment, the first width of the first part 44 includes but is not limited to being configured to be 1 millimeter, the width of the protruding part includes but is not limited to being configured to be 100 microns, and the second width of the second part 43 is correspondingly configured to be 1.2 millimeters.

[0105] In such an embodiment, the connecting conductor 4 designed with the above dimensions can ensure the contact area of the connecting conductor 4 with the corresponding electrode and reduce the contact resistance on the basis of effectively controlling the amount of material used for the connecting conductor 4.

[0106] In an illustrative embodiment, as shown in FIG. 2, the protruding parts are arranged on the main body part in the first direction with a spacing therebetween to form a second part 43 in the shape of a racetrack; correspondingly, the first part 44 between adjacent two second parts 43 forms a substantially rectangular structure.

[0107] FIG. 3 is a schematic diagram of a connecting conductor according to an illustrative embodiment.

[0108] In one illustrative embodiment, as shown in Fig. 3, the protrusions are arranged continuously along the first direction on the main body portion, so that the edges of the connecting conductor 4 extending along the first direction form a continuous wavy structure. Here, the first width is the maximum width of the portion where the connecting conductor 4 overlaps the insulating block 5. It should be understood that the embodiments of the present application are not limited thereto.

[0109] For example, the second portion 43 can also be configured in an elliptical shape, a rectangular shape, a polygonal shape, or other shapes suitable for connecting the electrode and the electrical connector 7 and forming a reliable connection.

[0110] Fig. 4 is a schematic view of a connecting conductor according to another illustrative embodiment.

[0111] As shown in Fig. 4, the connecting conductor 4 can be considered to have a main body portion (forming a substantially rectangular structure) extending along the first direction, and a plurality of protrusions protruding to both sides along the second direction are arranged at intervals along the first direction on the main body portion; the protrusions are arranged at positions corresponding to the second portions 43, so that the second width of the second portion 43 in the second direction is greater than the width of the first portion 44 in the second direction. The first portion 44 between two adjacent second portions 43 forms a substantially rectangular structure. Unlike Fig. 2, the protrusions shown in Fig. 4 have concave segments 46 at both ends in the second direction.

[0112] Fig. 5 is a schematic view of a connecting conductor according to yet another illustrative embodiment.

[0113] As shown in Fig. 5, the connecting conductor 4 protrudes to both sides to form protrusions at positions corresponding to the second portions 43, however, the edges of the connecting conductor 4 along the first direction on the insulating block 5 are in an arc shape concave from both ends to the middle, rather than a straight line. The protrusions arranged at positions corresponding to the second portions 43 can have concave segments 46 at both ends in the second direction (i.e., similar to the shape shown in Fig. 4).

[0114] In one illustrative embodiment, the back contact cell further comprises a plurality of thickened segments arranged at intervals along the first direction, the thickened segments being connected to the first electrode or the second electrode to which the second portion 43 is connected. The width of the thickened segment in the first direction is greater than the width of the first electrode or the second electrode to which the thickened segment is connected, so as to ensure sufficient contact area and reduce contact resistance. For example, Fig. 6 is a schematic view of the thickened segments 9 arranged when the connecting conductor shown in Fig. 4 is used, and the thickened segments 9 are arranged on the second electrode 3. It should be understood that when the second portion 43 is connected to the first electrode 2, the thickened segments 9 are arranged on the first electrode 2. When the connecting conductor is designed in other forms (such as shown in Figs. 3, 4, and 5), the thickened segments 9 can also be arranged on the electrode to which the second portion 43 is connected.

[0115] ​​​​​​​In an exemplary embodiment, the length of the thickened section in the second direction is 0.5-1.4 mm, and the width of the thickened section in the first direction is 0.1-0.5 mm. Specifically, the thickened section can be integrally formed with the first electrode or the second electrode to which the thickened section is connected, or the thickened section and the first electrode or the second electrode can be separately formed and then electrically connected.

[0116] FIG. 7 is a partial cross-sectional view of B1-B2 of the exemplary embodiment shown in FIG. 1.

[0117] In an exemplary embodiment, as shown in FIG. 7, the insulating blocks (i.e., the insulating pieces) above the second electrode 3 tend to have a cross-sectional shape that is generally arched (i.e., the middle portion of the second electrode 3 is upwardly convex, and the edge portions on both sides of the middle portion are relatively thin). Further, the connecting conductor 4 extends in the first direction (i.e., the left-right direction shown in FIG. 7), thereby forming the first portions 44 on the insulating blocks 5 and the second portions 43 between adjacent insulating blocks 5. It should be understood that, in FIG. 7, the connecting conductor 4 is shown as spanning two insulating blocks 5, and the connecting conductor 4 can span each insulating block 5 arranged in the first direction.

[0118] According to an embodiment of the present application, as shown in FIG. 7, the ratio of the thickness of the second portion 43 to the thickness of the first portion 44 is between 4 and 10.

[0119] In such an embodiment, the thickness of the second portion 43 is associated with the thickness of the first portion 44. If the thickness is too thin, the current transmission is not facilitated, and if the thickness is too thick, the material is wasted.

[0120] According to an embodiment of the present application, as shown in FIG. 7, the thickness of the second portion 43 is greater than or equal to 25 microns.

[0121] In such an embodiment, the second portion 43 is set to be relatively thick, which facilitates the reliability of the electrical connection between the second portion 43 and the external electrical connector in a soldered state, reduces the risk of poor soldering, and, under the condition that the width is unchanged, increases the cross-sectional area of the connecting conductor to reduce the resistance of the connecting conductor.

[0122] According to an embodiment of the present application, as shown in FIG. 7, the thickness of the first portion 44 is 5-15 microns.

[0123] In such an embodiment, for the thickness of the second portion 43 being greater than or equal to 25 microns, the first portion 44 should be set to an appropriate thickness. If the thickness is too thin, for example, corresponding to the upper limit of the thickness ratio of 10, the current transmission of the adjacent two fine grids is not facilitated. If the thickness is too thick, for example, corresponding to the lower limit of the thickness ratio of 4, the material of the connecting conductor is wasted, the improvement of the electrical conduction is small, and the connecting conductor can extend in the width direction during printing, thereby causing a short circuit due to the overlap with another opposite fine grid.

[0124] In an illustrative embodiment, the first portion 44 includes a first sub-portion that coincides with the projection of the connected first electrode 2 or second electrode 3 in the orthographic projection of the first surface, and a second sub-portion other than the first sub-portion. The thickness of the second portion 43 is greater than the thickness of the first sub-portion and the second sub-portion.

[0125] According to an embodiment of the present application, as shown in FIG. 7, the top surface of the first portion 44 protrudes from the top surface of the second portion 43 along a third direction (e.g., the up-down direction as shown in FIG. 7) that is orthogonal to both the first direction (e.g., the left-right direction as shown in FIG. 7) and the second direction (e.g., the direction perpendicular to the paper surface as shown in FIG. 1).

[0126] In an illustrative embodiment, the surface of the first portion 44 that faces away from the battery body 1 (e.g., the upper surface as shown in FIG. 7) protrudes upward more than the second portion 43. In this way, on the basis of saving the amount of paste used for the connecting conductor, the engagement force between the electrical connector 7 and the connecting conductor 4 is improved, the contact area is increased, the pulling force between the electrical connector 7 and the connecting conductor 4 is improved, and the contact resistance is reduced.

[0127] In an illustrative embodiment, as shown in FIG. 7, the surface of the first portion 44 and the second portion 43 that faces away from the battery body 1 (e.g., the upper surface as shown in FIG. 7) is formed with non-uniform protrusions 45. The protrusions on the second portion 43 protrude more than the protrusions on the first portion 44, so that the roughness of the surface of the second portion 43 is greater than the roughness of the surface of the first portion 44 (the roughness can be considered as the average roughness of the curved surface).

[0128] In such an embodiment, the protrusions 45 on the second portion 43 protrude more than the protrusions on the first portion 44, so that the surface of the second portion 43 is rougher. In this way, when the connecting conductor 4 is connected to the external electrical connector 7 and the engagement portion 6, a larger contact area is formed, the pulling force between the electrical connector 7 and the connecting conductor 4 is improved, and the contact resistance is more effectively reduced. The relatively smooth first portion 44 can avoid the situation that some of the protrusions 45 protrude too much and pierce the insulating block.

[0129] In an illustrative embodiment, as shown in FIG. 7, the surface of the second portion 43 of the connecting conductor 4 between adjacent two insulating blocks 5 that faces away from the battery body 1 (e.g., the upper surface as shown in FIG. 7) is formed with a substantially curved surface. In detail, the roughness of the surface of the first portion 44 that faces away from the battery body 1 is a first average roughness, and the roughness of the surface of the second portion 43 that faces away from the battery body 1 is a second average roughness; the first average roughness is less than the second average roughness. Specifically, the first average roughness is less than 10 microns, and the second average roughness is greater than or equal to 5 microns.

[0130] The second average roughness (i.e. Ra2) includes, but is not limited to, being configured to be greater than or equal to 5 microns, i.e. Ra2≥ 5 μm. Further, the maximum protrusion of the second portion 43 along the height perpendicular to the first surface is greater than or equal to 8 microns. It should be appreciated that embodiments of the present application are not limited thereto. For example, the surface of the second portion 43 facing away from the battery body 1 can also be configured to have an average roughness of 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 10 μm, 20 μm, and any other average roughness greater than 5 μm as appropriate to meet the corresponding welding and electrical requirements.

[0131] It should be noted that the average roughness refers to the average distance of the profile close to the outer side of the battery tab (close to the electrical connector) from the reference line (the reference line of the base of the protrusions) within the sampling length, which is used to reflect the overall roughness level of the surface. The greater the value of the average roughness, the rougher the surface, the smaller the surface undulation, and the better the flatness. When measuring, the values of the points at 20 different positions on the sampling length of at least 50 microns on the cross section (such as the cross section in FIG. 7) are tested respectively, and the average value is calculated.

[0132] In an illustrative embodiment, to form the connection conductor 4 having the above-mentioned second average roughness, an organic component (and the organic component includes 2% to 5% of epoxy resin) having a weight component greater than 5% can be configured in the paste (such as silver paste) for printing the main grid, and then sintering at 500-800°C. During the sintering process, due to the overflow of the decomposition of the organic material, the surface of the formed connection conductor presents a rough surface, i.e. the roughness is greater than 5 microns. It should be appreciated that embodiments of the present application are not limited thereto.

[0133] For example, it can also be achieved by other processes such as doctor blading, spraying, etc. In such an implementation, by configuring the second average roughness of the second portion 43 of the connection conductor 4 to be greater than or equal to 5 microns, the second portion 43 can form a relatively rough surface. In this way, it is beneficial to form a larger contact area when the connection conductor 4 is welded with the external electrical connector 7 or the solder, so as to more effectively reduce the contact resistance and help form a larger intermetallic compound layer to provide greater pull-out resistance. By configuring the first roughness to be less than 10 microns, the protruding part formed by the surface of the first portion 44 can be smaller, so as to avoid the situation of piercing the insulating layer caused by the protruding part being too protruding. For example, the surface of the first portion 44 facing away from the battery body 1 can also be configured to have an average roughness of 1 μm, 2 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 9 μm, and any other average roughness less than 10 μm, but at the same time needs to ensure that the average roughness of the surface of the second portion 43 facing away from the battery body 1 is less than that of the first portion 44.

[0134] According to embodiments of the present application, the material of the connecting conductor 4 includes, but is not limited to, aluminum, copper, silver-coated copper, or silver-copper alloy.

[0135] In an exemplary embodiment, as shown in FIG. 7, the width of the second electrode 3 along the first direction (i.e., W4 as shown in FIG. 7) includes, but is not limited to, being configured to be between 30 microns and 100 microns. And / or, the width of the first electrode 2 along the first direction (i.e., W5 as shown in FIG. 7) includes, but is not limited to, being configured to be between 30 microns and 100 microns.

[0136] In such an embodiment, the first electrode 2 and the second electrode 3 are configured to have a narrow width, which helps to improve the fill factor and output power of the back contact cell, and helps to optimize the current flow path to reduce current congestion and potential loss points.

[0137] In an exemplary embodiment, the first electrode 2 and the second electrode 3 can be formed by printing, such as screen printing, as shown in FIG. 7, in which case the width of the first electrode 2 and the second electrode 3 can both be between 30 microns and 100 microns. In detail, the second electrode 3 is disposed on the multi-carrier (i.e., majority carrier) doped region, and the first electrode 2 is disposed on the few-carrier (i.e., minority carrier) doped layer. Further, the width of the second electrode 3 (i.e., W4) is configured to be smaller than the width of the first electrode 2 (i.e., W5), i.e., 30 μm≤W4≤100 μm, 30 μm≤W5≤100 μm, and W4

[0138] In such an embodiment, taking a cell body with an n-type silicon wafer as a substrate as an example, electrons are majority carriers and holes are minority carriers. Accordingly, the p-type doped region is used as a minority carrier region for collecting minority carriers, i.e., holes; and the n-type doped region is used as a multi-carrier region for collecting majority carriers, i.e., electrons. Based on the characteristics of the back contact cell, when the first electrode 2 collects minority carriers, holes will also be transported in the substrate in a transverse direction. In this process, holes are prone to recombine with majority carriers in the multi-carrier region. Therefore, the first electrode 2 disposed in the minority carrier doped region is configured to be wider, which can more effectively improve the collection efficiency of the first electrode 2 for minority carriers.

[0139] In an exemplary embodiment, the first electrode 2 and the second electrode 3 can be directly connected with the corresponding doped region, or a transparent conductive oxide (e.g. TCO) layer can be arranged between the electrode (i.e. the first electrode 2 and the second electrode 3) and the corresponding doped region. Based on the collection efficiency of the minority carriers as described above, the minority doped region and / or the transparent conductive oxide layer on the minority doped region can be designed to be wider accordingly, so as to further improve the collection efficiency of the minority carriers. The first electrode 2 and / or the second electrode 3 can be formed on the cell body 1 by electroplating, evaporation, vapor deposition, etc.

[0140] Similarly, for example, the cell body with a p-type silicon wafer as the substrate, the electrons are minority carriers, and the holes are majority carriers. Therefore, the electrode on the minority doped region should also be arranged to be wider, and the specific effect will not be described here. It should be understood that the embodiments of the present application are not limited thereto.

[0141] For example, the width of the first electrode 2 and the second electrode 3 can be set to be substantially equal.

[0142] For another example, the width of the first electrode 2 can be set to be greater than the width of the second electrode 3. The specific effect should be to meet the collection requirements of the corresponding photo-generated carriers, which will not be described here.

[0143] In an exemplary embodiment, as shown in FIG. 7, the first electrode 2 and the second electrode 3 form an isolation region along the first direction. In detail, the insulating block 5 extends from the upper part of the second electrode 3 to the isolation region and is arranged to be spaced apart from the first electrode 2. The part between the insulating block 5 and the first electrode 2 is covered by the connecting conductor 4 (the covered part is only the area within the width range of the connecting conductor 4), so as to maintain the insulation effect between the first electrode 2 and the second electrode 3 (and the connecting conductor 4), while reserving sufficient width to ensure that the connecting conductor can be in full contact with the second electrode.

[0144] In another exemplary embodiment, not shown in the figure, the first electrode 2 and the second electrode 3 can be formed by deposition process such as electroplating. At this time, in the first direction, the width of the first electrode 2 is 300 microns to 600 microns. And / or, the width of the second electrode 3 is 300 microns to 600 microns.

[0145] In an exemplary embodiment, the width of the first electrode 2 and the second electrode 3 can be 300-600 microns. In detail, the second electrode 3 is disposed on the multi-carrier (i.e. multi-carrier) doped region, and the first electrode 2 is disposed on the minority carrier (i.e. minority carrier) doped layer. Further, the width of the second electrode 3 (i.e. W4) is configured to be smaller than the width of the first electrode 2 (i.e. W5), i.e. 300 μm≤W4≤600 μm, 300 μm≤W5≤600 μm, and W4

[0146] In this embodiment, the width of the first electrode 2 is set to be wider, and the resulting technical effect is similar to the above-mentioned embodiment shown in FIG. 7, that is, the electrode (i.e. the first electrode 2) disposed on the minority carrier doped region is set to be wider, so as to improve the collection effect of the minority carriers. Therefore, no further description is given.

[0147] In such an embodiment, the first surface is the back surface of the back contact cell, and therefore, there is no need to consider the light shielding loss. On this basis, by increasing the width of the first electrode 2 and the second electrode 3 and the area ratio of the first surface occupied by the first electrode 2 and the second electrode 3, the current collection efficiency can be effectively improved, especially the collection efficiency of the minority carriers on the minority carrier doped region. In addition, the electrode with a larger width can also increase the cross-sectional area, which can effectively reduce the series resistance. In addition, the wider first electrode 2 and the second electrode 3 can also more evenly distribute the electric field, and provide support for the battery body 1, which is still beneficial to improve the structural strength of the battery body.

[0148] Based on the above-mentioned embodiments, the part of the battery body 1 between the adjacent first electrode 2 and the second electrode 3 forms an isolation region. The insulating block 5 covers the isolation region and extends to the first electrode 2 or the second electrode 3. Specifically, if the insulating block 5 is disposed between the connecting conductor 4 and the second electrode 3, as shown in FIG. 7, the insulating block 5 covers the isolation region and extends to the first electrode 2; if the insulating block 5 is disposed between the connecting conductor 4 and the first electrode 2, the insulating block 5 covers the isolation region and extends to the second electrode 3.

[0149] Under the premise that the width of the battery body 1 is limited, the width of the first electrode 2 and the second electrode 3 is set to be wider, so that the spacing of the first electrode 2 and the second electrode 3 in the first direction is smaller. Therefore, the entire isolation region is covered by the insulating block 5, and extends to the first electrode 2 or the second electrode 3, which can be used to maintain the insulation of the first electrode 2 and the second electrode 3 in the first direction, and can also prevent the connecting conductor 4 from entering the isolation region, so as to avoid the leakage caused by the excessive electric field strength in the isolation region.

[0150] In an exemplary embodiment, the connecting conductor 4 is made of silver-coated copper, but is not limited thereto. In detail, the connecting conductor 4 is printed with a copper inner layer, and after sintering, a silver outer layer is printed and sintered again to melt the silver particles and combine with the copper main grid to form a silver-coated copper structure.

[0151] In such an embodiment, the connecting conductor 4 is made of silver and copper, which reduces the amount of silver paste used and thus reduces the corresponding process cost. In addition, the high electrical conductivity and corrosion resistance of the connecting conductor are also taken into account. It should be understood that the embodiments of the present disclosure are not limited thereto.

[0152] For example, the connecting conductor 4 can also be made of silver only; for example, the connecting conductor 4 can also be made of other base metals, such as pure copper, pure aluminum, etc.; or the connecting conductor 4 can also be made of other alloy materials.

[0153] FIG. 8 is a schematic view of a connecting conductor according to another exemplary embodiment.

[0154] In an exemplary embodiment, as shown in FIG. 8, the connecting conductor 4 further includes a bonding pad 10, the bonding pad 10 is at least partially disposed on the insulating block, and the width of the bonding pad 10 in the second direction is greater than the second width of the second part 43. Further, the length of the bonding pad 10 in the first direction is greater than the length of at least two second parts 43 in the first direction. The bonding pad 10 covers at least one insulating block, and needs to be electrically connected to the first electrode 2 or the second electrode 3 to be connected, for example, as shown in FIG. 8, the bonding pad 10 is disposed on three insulating blocks and connects two second electrodes 3. In some other embodiments, the bonding pad 10 is disposed on two insulating blocks and connects three second electrodes 3, or can be in other covering modes.

[0155] Optionally, a plurality of bonding pads 10 can be disposed in the first direction of the connecting conductor 4, for example, 5-10 bonding pads 10 as shown in FIG. 8 can be disposed in the first direction on each connecting conductor 4, which can be integrally printed and formed with the first part 44 and the second part 43. Further, the two ends of the bonding pad 10 in the second direction can also have a protruding part (as shown in FIG. 8, the protruding parts on the left and right sides of the bonding pad 10), which can also increase the bonding area between the connected electrodes and reduce the contact resistance. The bonding pad 10 can be integrally printed and formed with the first part 44 and the second part 43, i.e., integrally formed, and in some other embodiments, the bonding pad 10 can be printed separately from the first part 44 and the second part 43, i.e., printed in two steps.

[0156] As shown in FIG. 1, when the connecting conductor 4 is not provided with the bonding pad 10, and the second portion 43 is connected with the external electrical connector 7, since the width of the second portion 43 is larger, the second portion 43 has a larger contact area than the first portion 44. Therefore, a bonding portion 6 with a larger area can be formed between the second portion 43 and the electrical connector 7, which is beneficial to improve the tensile force between the connecting conductor 4 and the electrical connector 7.

[0157] FIG. 9 is a schematic diagram of a top view of a photovoltaic module according to an illustrative embodiment of the present application.

[0158] Based on the same inventive concept, the present application also provides a photovoltaic module, as shown in FIG. 9, which includes a back contact cell and an electrical connector 7 (which can also be called a ribbon or interconnection strip, and is used to connect at least two back contact cells in series). The electrical connector 7 is electrically connected with the connecting conductor 4 of the at least two back contact cells. The electrical connector 7 and the connecting conductor 4 are provided with a bonding portion 6.

[0159] In an illustrative embodiment, the bonding portion 6 can be a solder, which can also be called a solder paste, such as soldering tin. The bonding portion 6 is used to connect with the second portion 43 of the connecting conductor 4 or the bonding pad 10. Further, before the connecting conductor 4 is soldered with the electrical connector 7, the solder should be pre-set on the second portion 43 of the connecting conductor 4 or the bonding pad 10. Since the second portion 43 and the bonding pad 10 have a larger area, when the connecting conductor 4 is soldered with the electrical connector 7, the solder can form a larger specific surface area when melted, so as to improve the soldering tensile force.

[0160] In another illustrative embodiment, the bonding portion 6 can be an adhesive with electrical conductivity, such as conductive glue, tin paste, etc. Further, in the embodiment in which the conductive glue is used to connect the connecting conductor 4 with the electrical connector 7, the electrical connector 7, the conductive glue and the connecting conductor 4 are stacked. In a preferred embodiment, the thickness (i.e. height) of the electrical connector 7 includes but is not limited to being configured to be between 100-250 microns (such as 200 microns), the thickness (i.e. height) of the conductive glue includes but is not limited to being configured to be between 10-50 microns (such as 25 microns), and the thickness (i.e. height) of the connecting conductor 4 includes but is not limited to being configured to be between 20-60 microns (such as 40 microns).

[0161] In such an embodiment, the electrical connector 7 is used to connect the connecting conductors 4 of different back contact cells, and the connecting conductors 4 of adjacent back contact cells have opposite polarities, so that a plurality of back contact cells can be connected in series to form a cell string. FIG. 10 is a partial cross-sectional view of the photovoltaic module of the illustrative embodiment shown in FIG. 9 along a first direction.

[0162] According to the embodiments of the present application, as shown in FIG. 9 and FIG. 10, a plurality of joints 6 are arranged between the electrical connector 7 and the connecting conductor 4 in the first direction, and at least some of the plurality of joints 6 are arranged on the second part 43 of the connecting conductor 4. In an exemplary embodiment, as shown in FIG. 9 and FIG. 10, the joints 6 are arranged on the second part 43 at intervals, i.e., the first of the two adjacent second parts 43 is provided with a joint 6. In detail, in the orthographic projection in the third direction (the direction perpendicular to the paper plane as shown in FIG. 9), the joint 6 can coincide with the projection of the electrode (i.e., the first electrode 2 or the second electrode 3), or can be staggered with the projection of the electrode (i.e., the first electrode 2 or the second electrode 3). In this way, the use of joint 6 material can be saved, and the effect of electrical interconnection close to the continuous joint 6 can also be achieved. Further, the joints 6 are preferably arranged at equal intervals in the first direction (the up-down direction as shown in FIG. 9). It should be understood that the embodiments of the present application are not limited thereto.

[0163] For example, the joint 6 can be arranged on each second part 43 of the connecting conductor 4. In such an implementation, the second part 43 of the connecting conductor 4 serves as the main joint point for connecting the electrode (the first electrode 2 or the second electrode 3) to the electrical connector 7. By arranging the joint 6 on the second part 43, the joint 6 can have a larger joint area to effectively and firmly connect the connecting conductor 4 and the electrical connector 7 together, and the equally spaced joints 6 are beneficial to reduce the risk of cracking of the soldering.

[0164] According to the embodiments of the present application, the joint 6 is preferably arranged completely on the second part 43 with a larger width, which can shorten the current transmission path; and the joint 6 and the connecting conductor 4 have a larger bonding area.

[0165] According to the embodiments of the present application, the number of joints 6 arranged on the second part 43 of the same connecting conductor 4 is between 15 and 24, which is not shown in the figure.

[0166] In an exemplary embodiment, the number of joints 6 arranged on the second part 43 of the connecting conductor 4 is preferably configured to be any number between 18 and 21. Further, the spacing between adjacent joints 6 is preferably configured to be 3.8-4.2 millimeters, such as 3.9 millimeters. It should be understood that the embodiments of the present application are not limited thereto.

[0167] For example, the number of joints 6 can also be configured to be 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, or any other number, as appropriate to the length of the connecting conductor 4 and the spacing requirement between adjacent joints 6. Among them, the length of the connecting conductor 4 includes but is not limited to being configured to be between 90-110 millimeters.

[0168] In one exemplary embodiment, the length of the connecting conductor 4 (i.e. the distance between the two ends in the first direction) comprises, but is not limited to, being configured to be 90-110 mm. Further, the number of the junctions 6 provided on the connecting conductor 4 is preferably configured to be any number between 18-21.

[0169] In such an embodiment, the junctions 6 in the above number can provide a pulling force of 1N (i.e. Newton) or above between the connecting conductor 4 and the electrical connector 7. Accordingly, as the number of the junctions 6 increases, the pulling force between the connecting conductor 4 and the electrical connector 7 also gradually increases, but the increase in the number and the pulling force is non-linear. Therefore, if the number of the junctions 6 is configured to be too large, the pulling force between the connecting conductor 4 and the electrical connector 7 cannot be significantly improved, and the material for preparing the junctions 6 will be wasted. Therefore, the number of the junctions configured to be in the above number can provide a suitable pulling force, so that the connecting conductor 4 and the electrical connector 7 can be reliably connected, and the material for preparing the junctions 6 can be prevented from being wasted.

[0170] In another exemplary embodiment, a plurality of junctions 6 are provided between the electrical connector 7 and the connecting conductor 4 in the first direction, and the junctions 6 are provided on the junction pads 10 of the connecting conductor 4. It can be understood that when the connecting conductor 4 is not provided with the junction pads 10, the junctions 6 are connected to the second part 43. In this case, the first number of the junctions is greater than the second number of the junctions 6 connected to the junction pads 10 when the connecting conductor 4 is provided with the junction pads 10, and the number of the junction pads 10 is 4-12.

[0171] Fig. 11 is a partial cross-sectional view of the photovoltaic module along the first direction according to another exemplary embodiment of Fig. 9.

[0172] In other exemplary embodiments, the junctions 6 can also be located on at least two adjacent electrodes (the first electrodes 2 or the second electrodes 3), for example, as shown in Fig. 11, the junctions 6 are located on at least two adjacent second electrodes 3. Further, the junctions 6 extend on each of the first electrodes 2 and the second electrodes 3 in the first direction. The junctions 6 are continuous in the extension direction of the electrical connector 7, and can be densely provided by a plurality of spaced junctions, and finally fused to be integrated to form the junctions 6 of Fig. 11.

[0173] As shown in Fig. 11, the air gap 8 is formed between the junctions 6 and the first part 44 of the connecting conductor 4.

[0174] In one exemplary embodiment, as shown in FIG. 11, the bonding portion 6 is continuously arranged between the electrical connector 7 and the connecting conductor 4. In this embodiment, the bonding portion 6 is discretely arranged on the connecting conductor 4 before being pressed by the electrical connector 7, and then is thinned and extended in the first direction by pressing (the pressing methods include, but are not limited to, film adhesion, a press head machine, or any other method). In detail, the bonding portion 6 is spaced apart from the top of the insulating block 5 and forms the air gap 8. In this embodiment, since the bonding portion 6 has formed a good electrical connection with the electrode, the portion forming the air gap 8 can not be connected to the first portion. In this way, the amount of the bonding portion 6 (i.e., solder paste) can be reduced.

[0175] In another exemplary embodiment, not shown in the drawings, the bonding portion 6 can be continuously arranged on the connecting conductor 4 (e.g., in the form of a strip), and then substantially completely fills the space between the electrical connector 7 and the connecting conductor 4 (i.e., substantially no air gap 8 is formed) after pressing. In this way, the embodiment shown in FIG. 11 can form a better electrical connection between the electrical connector 7 and the connecting conductor 4, providing greater pull-out resistance, but also requires a larger amount of the bonding portion 6 (i.e., solder paste). Therefore, the specific arrangement of the bonding portion 6 should be comprehensively set according to the electrical connection performance and the pull-out resistance required by the photovoltaic module.

[0176] According to an embodiment of the present application, as shown in FIG. 9, the third distance (i.e., S3 in FIG. 9) between the end of the electrical connector 7 located in the cell body 1 of the back contact cell (e.g., the upper end of the leftmost electrical connector in FIG. 9) and the first edge (e.g., the upper edge in FIG. 9) of the cell body 1 adjacent to the end is between 1-5 mm (i.e., 1 mm≤S3≤5 mm). In a preferred embodiment, the third distance can be configured to be about 4.0 mm.

[0177] According to an embodiment of the present application, the third distance S3 is greater than the second distance S1, and the third distance S3 is greater than the first distance S2. In this way, the solder strip can be prevented from protruding from the cell body 1 to cause short circuit.

[0178] Based on the structural characteristics of the back contact cell, the closer to the edge of the cell body, the more likely to cause hidden cracks under stress. Therefore, in the above embodiments, the third distance between the electrical connector 7 and the edge of the cell body 1 can prevent the hidden cracks of the cell body 1 caused by connecting (e.g., welding or bonding) the electrical connector 7 and the connecting conductor 4.

[0179] FIG. 12 is a schematic top view of a back contact cell according to an exemplary embodiment of the present application.

[0180] According to the embodiments of the present application, the connecting conductor 4 is arranged at the edge close to at least one of the opposite two first sides of the battery body 1. As shown in FIG. 12, the edge region (A region) close to the first side of the battery body 1 is provided with the connecting conductor 4, which is the main grid, and the middle region (B region) away from the first side of the battery body 1 is not provided with the connecting conductor 4, i.e., the middle region is not provided with the main grid. In general, along the extension direction of the connecting conductor 4, the width of the edge region along the first direction is much smaller than the width of the middle region along the first direction, and the length of the connecting conductor 4 along its extension direction within a single edge region can be 3-12 mm.

[0181] According to the embodiments of the present application, due to the limitations of the solder strip preparation process and equipment, it is difficult to form the solder strip at the edge of the back surface of the back contact battery (the solder strip formed at the edge of the back surface is prone to cause short circuit), and therefore it is difficult to collect the current on the fine grid at the edge of the back surface of the back contact battery. By forming the first connecting conductor 41 and the second connecting conductor 42 at the edge of the back surface of the back contact solar cell, it is more conducive to collect the carriers at the edge of the back surface, and it is conducive to improving the efficiency of the battery.

[0182] It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only the directions of the drawings, and are not intended to limit the protection scope of the present application. Throughout the drawings, the same elements are represented by the same or similar reference numerals. When it may cause confusion to the understanding of the present application, the conventional structures or configurations will be omitted.

[0183] The embodiments of the present application are described above. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the present application. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present application is defined by the appended claims and their equivalents. Without departing from the scope of the present application, those skilled in the art can make various substitutions and modifications, which should all fall within the scope of the present application.

Claims

1. A back contact cell, characterized in that, The battery body (1) has opposite first and second surfaces; A first electrode (2) and a second electrode (3) are provided on the first surface of the battery body (1), the first electrode (2) and the second electrode (3) are alternately and spacedly arranged in a first direction and extend in a second direction perpendicular to the first direction; A connecting conductor (4) is provided on the first surface and extends in the first direction, the connecting conductor (4) is connected to one of the first electrode (2) and the second electrode (3) and is provided with an insulating block (5) between the other one; The connecting conductor (4) includes a first part (44) provided on the insulating block (5) and a second part (43) provided between two adjacent insulating blocks (5) in the first direction, a first width of the first part (44) in the second direction is smaller than a second width of the second part (43) in the second direction. The second part (43) protrudes from the first part (44) at both ends in the second direction, the width of the part protruding from the first part (44) at each end of the second part (43) in the second direction is between 80-250 microns.

2. The back contact cell of claim 1, wherein, The first width is between 0.5-1.5 millimeters.

3. The back contact cell of claim 1, wherein, The battery body (1) has a first edge extending in the second direction; 4. The back contact cell of claim 1, wherein, The connecting conductor (4) includes a first connecting conductor (41) connected to the first electrode (2) and provided with the insulating block (5) between the second electrode (3), the second part (43) of the first connecting conductor (41) closest to the first edge is provided between two adjacent insulating blocks (5) in the first direction. The connecting conductor (4) includes a second connecting conductor (42) connected to the second electrode (3) and provided with the insulating block (5) between the first electrode (2); 5. The back contact cell of claim 4, wherein, The second part (43) of the second connecting conductor (42) closest to the first edge is provided between the first edge and the insulating block (5) adjacent to the first edge. The first spacing between the end of the first connecting conductor (41) adjacent to the first edge and the first edge is greater than the second spacing between the end of the second connecting conductor (42) adjacent to the first edge and the first edge.

6. The back contact cell of claim 5, wherein, The first spacing is between 1-3 millimeters.

7. The back contact cell of claim 6, wherein, The second spacing is between 0.5-1.5 millimeters.

8. The back contact cell of claim 6, wherein, The ratio of the thickness of the second part (43) to the thickness of the first part (44) is between 4-10.

9. The back contact cell of claim 1, wherein, The thickness of the first part (44) is between 5 microns and 15 microns.

10. The back contact cell of claim 9, wherein, The thickness of the second part (43) is greater than or equal to 25 microns.

11. The back contact cell of claim 9, wherein, The first part (44) includes a first subpart coinciding with the projection of the connected first electrode (2) or second electrode (3) in the orthogonal projection of the first surface, and a second subpart other than the first subpart; 12. The back contact cell of claim 1, wherein, The thickness of the second part (43) is greater than the thickness of the first subpart and the second subpart. ​ 13. The back contact cell of claim 1 wherein, The top surface of the first portion (44) is higher than the top surface of the second portion (43) in a third direction orthogonal to both the first direction and the second direction.

14. The back contact cell of claim 1 wherein, The material of the connecting conductor (4) includes aluminum, copper, silver-coated copper, or silver-copper alloy.

15. The back contact cell of claim 5, wherein, The connecting conductor (4) is disposed near an edge of at least one of the two opposite first sides of the battery body (1).

16. The back contact cell of claim 1, wherein, The surface of the first portion (44) facing away from the battery body (1) has a first average roughness, and the surface of the second portion (43) facing away from the battery body (1) has a second average roughness, wherein the first average roughness is less than the second average roughness.

17. The back contact cell of claim 16, wherein, The second average roughness is greater than or equal to 5 microns.

18. The back contact cell of claim 16, wherein, The first average roughness is less than 10 microns.

19. The back contact cell according to any of claims 16-18, wherein, The surfaces of the first portion (44) and the second portion (43) facing away from the battery body (1) are both formed with non-uniform protrusions (45), and the maximum protrusion of the second portion (43) has a height perpendicular to the first surface that is greater than or equal to 8 microns.

20. The back contact cell of claim 1 wherein, In the first direction, the width of the first electrode (2) is 30 microns to 100 microns, and / or the width of the second electrode (3) is 30 microns to 100 microns.

21. The back contact cell of claim 1 wherein, In the first direction, the width of the first electrode (2) is 300 microns to 600 microns, and / or the width of the second electrode (3) is 300 microns to 600 microns.

22. The back contact cell of claim 1 wherein, The portion of the battery body (1) between adjacent first electrodes (2) and second electrodes (3) forms an isolation region, and the insulating block (5) extends to the isolation region, or the insulating block (5) covers the isolation region and extends to the second electrode (3) or the first electrode (2).

23. The back contact cell of claim 1 wherein, Further comprising a plurality of thickened segments arranged at intervals in the first direction, the thickened segments being connected to the first electrode (2) or the second electrode (3) to which the second portion (43) is connected, and the width of the thickened segments in the first direction being greater than the width of the first electrode (2) or the second electrode (3) to which the thickened segments are connected.

24. The back contact cell of claim 1 wherein, The connecting conductor (4) further comprises a bonding pad (10) disposed on at least one insulating block (5), and the width of the bonding pad (10) in the second direction is greater than the second width of the second portion (43).

25. A photovoltaic module, characterized by, Comprising: The back contact battery of any one of claims 1 to 24; An electrical connector (7) electrically connecting the connecting conductors (4) of at least two of the back contact batteries.

26. The photovoltaic module of claim 25, wherein, A plurality of bonding portions (6) are arranged at intervals in the first direction between the electrical connector (7) and the connecting conductor (4).

27. The photovoltaic module of claim 26, wherein, The number of the bonding portions (6) arranged on the same connecting conductor (4) is between 15 and 24.

28. The photovoltaic module of claim 25, wherein, A plurality of bonding portions (6) are arranged at intervals in the first direction between the electrical connector (7) and the connecting conductor (4), and the bonding portions (6) are arranged on the bonding pad (10) of the connecting conductor (4).

29. The photovoltaic module of claim 25, wherein, The third distance between the end of the electrical connection (7) located inside the cell body (1) of the back contact cell and the first edge of the cell body (1) adjacent to this end is between 1 and 5 millimeters. The third distance between the end of the electrical connection (7) located inside the cell body (1) of the back contact cell and the first edge of the cell body (1) adjacent to this end is between 1 and 5 millimeters.

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