Back contact battery and photovoltaic module

Abstract

The invention provides a back contact battery and a photovoltaic module, and the back contact battery comprises a battery body which is provided with a first surface and a second surface which are opposite to each other; the first electrodes and the second electrodes are arranged on the first surface of the battery body, and the first electrodes and the second electrodes are sequentially and alternately arranged at intervals in the first direction and extend in the second direction; the connecting conductor is arranged on the first surface and extends in the first direction, an insulating layer is arranged between the connecting conductor and the first electrode, and the connecting conductor is connected with the second electrode; each connecting conductor comprises a first part located between two adjacent insulating layers in the first direction and a second part overlapped with the projection of the first electrode in the orthographic projection of the first surface, the surface, deviating from the battery body, of the first part has first average roughness, and the surface, deviating from the battery body, of the second part has second average roughness, the second average roughness is smaller than the first average roughness.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the field of photovoltaic technology, and in particular to a back contact cell and a photovoltaic module. Background Art

[0002] In a back-contact battery, the positive and negative sub-grids are respectively arranged on different doping regions on the backlight side of the battery body, and then connected to the main grid of the same polarity to collect the current generated by the battery body.

[0003] The main grid and the auxiliary grid are arranged in different directions. Therefore, when the main grid is connected to the auxiliary grid of the same polarity, it will also cross the auxiliary grid of different polarity. In order to prevent the main grid from connecting the auxiliary grids of different polarities and causing a short circuit, an insulating layer needs to be arranged between the main grid and the auxiliary grids of different polarities, that is, the overlapping part of the printed main grid and the auxiliary grids of different polarities is formed on the insulating layer.

[0004] Based on the material characteristics of the insulating layer, the surface of the insulating layer that faces away from the battery body is protruding from the battery body and is relatively smooth, which is conducive to accumulating more paste for printing the main grid in the area between adjacent insulating layers. In this way, the portion of the main grid located in this area can be thicker, which is conducive to improving the reliability of the electrical connection between the main grid and the auxiliary grid of the same polarity, but the surface of this portion that faces away from the battery body tends to form a roughly arched shape and is relatively smooth. This smooth surface is not conducive to forming an effective connection with the external interconnection bar, and is likely to cause the problem of poor contact between the main grid and the interconnection bar. Summary of the invention

[0005] In order to solve at least one of the above-mentioned and other technical problems in the prior art, the present invention provides a back-contact cell and photovoltaic module, which is conducive to setting a bonding layer on the connecting conductor to improve the reliability of the connection between the connecting conductor and the electrical connector.

[0006] An embodiment of the present invention provides a back-contact battery, including a battery body having a first surface and a second surface relative to each other; a first electrode and a second electrode, which are arranged on the first surface of the battery body, the first electrode and the second electrode are arranged alternately and spaced in sequence along a first direction, and extend along a second direction, and the first direction intersects with the second direction; a connecting conductor, which is arranged on the first surface, the connecting conductor extends along the first direction, an insulating layer is arranged between the connecting conductor and the first electrode, and the connecting conductor is connected to the second electrode; the connecting conductor includes a first portion located between two adjacent insulating layers along the first direction and a second portion overlapping with the projection of the first electrode in the orthographic projection of the first surface, the surface of the first portion facing away from the battery body has a first average roughness, and the surface of the second portion facing away from the battery body has a second average roughness, wherein the second average roughness is smaller than the first average roughness.

[0007] In the case of adopting the above embodiment, the second average roughness is configured to be smaller than the first average roughness, that is, the second portion is smoother, has less surface undulations, and has better flatness than the first portion. The relatively rough first portion is conducive to connection with external electrical connectors or solder, and has better welding quality. The relatively smooth second portion is conducive to preventing the connecting conductor from piercing the insulating layer covering the first electrode when it is welded or laminated with the external electrical connector, thereby avoiding leakage and short circuit.

[0008] In some exemplary embodiments, the first average roughness is greater than or equal to 5 micrometers.

[0009] When adopting the above-mentioned embodiment, the first average roughness is configured to be greater than or equal to 5 microns, which is beneficial to forming a larger contact area when the connecting conductor is welded with the external electrical connector or solder, so as to more effectively reduce the contact resistance, and help form a larger area of ​​the intermetallic compound layer to provide greater pull-out resistance.

[0010] In some exemplary embodiments, the second average roughness is less than 10 micrometers.

[0011] When adopting the above-mentioned embodiment, in addition to making the raised portion formed on the surface of the second part smaller to avoid piercing the insulating layer, limiting the second average roughness can also prevent the occurrence of solder bridges, cold welding or reduced welding quality caused by uneven distribution of solder thereon.

[0012] In some exemplary embodiments, a surface of the first portion facing away from the first surface has a plurality of first protrusions, and a maximum height of the plurality of first protrusions along a direction perpendicular to the first surface is greater than or equal to 8 micrometers.

[0013] In the case of the above embodiment, the first protrusion formed on the first portion has a greater height (and greater surface undulations), which helps to improve the joining force between the electrical connector and the connecting conductor, increase the contact area, and reduce the contact resistance.

[0014] In some exemplary embodiments, a ratio of a thickness of the first portion to a thickness of the second portion is between 4-10.

[0015] When adopting the above-mentioned embodiment, the thickness of the first part is related to the thickness of the second part. The thicker first part can ensure the reliability of welding, and the thinner second part can realize the electrical transmission of adjacent isotropic fine grids along the extension direction of the connecting conductor, thereby preventing the problem of partial poor joining. A second part that is too thin is not conducive to the transmission of current, and a second part that is too thick will lead to waste of materials. The present application achieves a balance between material cost and electrical transmission effect by setting the thickness ratio to 4-10.

[0016] In some exemplary embodiments, the thickness of the first portion is greater than or equal to 25 micrometers.

[0017] When the above embodiment is adopted, setting the first part thicker is beneficial to maintaining its reliability with the external electrical connector in the welding state, reducing the risk of poor welding, and under the condition of unchanged width, it can also increase the cross-sectional area of ​​the connecting conductor to reduce the resistance of the connecting conductor.

[0018] In some exemplary embodiments, the thickness of the second portion is 5 micrometers to 15 micrometers.

[0019] In the case of the above embodiment, when the thickness of the first part is greater than or equal to 25 microns, the second part should be set to a suitable thickness. If it is set too thin, such as the upper limit value corresponding to the thickness ratio of 10, it is not conducive to the current transmission of two adjacent fine grids; and if it is set too thick, such as the lower limit value corresponding to the thickness ratio of 4, it not only wastes the material of the connecting conductor, but also has little improvement on electrical conduction, and may cause the connecting conductor to extend in the width direction during printing, and then cause overlap with another opposite fine grid to cause a short circuit.

[0020] In some exemplary embodiments, the connecting conductor further includes a third portion that overlaps with a projection of the insulating layer in an orthographic projection of the first surface; and a thickness of the first portion is greater than a thickness of the third portion.

[0021] In the case of the above-mentioned embodiment, the first part is used as the main connection point between the connecting conductor and the external electrical connector. Setting it thicker is beneficial to making the joint position with the electrical connector have better welding quality; correspondingly, the third part is not particularly thick, which can make the surface of the connecting conductor roughly flush, so as to reduce the warping deformation of the electrical connector after lamination.

[0022] In some exemplary embodiments, the thickness of the third portion is less than or equal to 25 micrometers.

[0023] In some exemplary embodiments, the width of the first electrode is 30 micrometers to 100 micrometers; and / or the width of the second electrode is 30 micrometers to 100 micrometers.

[0024] The portion of the battery body located between the adjacent first electrode and the second electrode forms an isolation region; the insulating layer covers a portion of the isolation region.

[0025] When a narrower electrode is formed by printing methods such as silk screen printing, the insulating layer extends to the isolation area so that the side of the first electrode along the first direction is covered by the insulating layer, which is beneficial to maintaining the insulation effect between the first electrode and the second electrode and the connecting conductor, while reserving sufficient width to ensure that the connecting conductor can fully contact the second electrode.

[0026] In some illustrative embodiments, the width of the first electrode is 300 microns to 600 microns; and / or, the width of the second electrode is 300 microns to 600 microns. When a wider electrode is formed by electroplating, deposition, etc., when the first surface is the backlight surface of the back contact battery, there is no need to consider its shading loss. On this basis, a wider first electrode and a second electrode are provided to increase the area ratio of the first electrode and the second electrode to the first surface. In this way, the current collection efficiency can be effectively improved, especially the collection efficiency of minority carriers on the minority carrier doping region, and the provision of a wider electrode can also increase its cross-sectional area, which can effectively reduce the series resistance. In addition, the wider first electrode and the second electrode can also distribute the electric field more evenly and provide support for the battery body, which is beneficial to improve the structural strength of the back contact battery.

[0027] In some exemplary embodiments, the portion of the battery body located between the adjacent first electrode and the second electrode forms an isolation region; the insulating layer covers the isolation region and extends to the second electrode. For the wider first electrode and the second electrode, the insulating layer extends to the electrodes of opposite polarity, which can ensure the insulation of the isolation region and also ensure that the width of the electrodes of the same polarity is smaller, so that the connecting conductor can save slurry at this location while ensuring a sufficient height of the first portion.

[0028] An embodiment of the present invention also provides a back-contact battery, including a battery body having a first surface and a second surface relative to each other; a first electrode and a second electrode, which are arranged on the first surface of the battery body, and the first electrode and the second electrode are arranged alternately in sequence along a first direction and extend along a second direction; a connecting conductor, which is arranged on the first surface, and the connecting conductor extends along the first direction, an insulating layer is arranged between the connecting conductor and the first electrode, and the connecting conductor is connected to the second electrode; the connecting conductor includes a first portion located between two adjacent insulating layers along the first direction, and the surface of the first portion facing away from the battery body has a plurality of first protrusions, and the maximum height of the plurality of first protrusions is greater than or equal to 8 microns.

[0029] In the case of the above embodiment, the first protrusion formed on the first portion has a greater height (and greater surface undulations), which helps to improve the joining force between the electrical connector and the connecting conductor, increase the contact area, and reduce the contact resistance.

[0030] In some exemplary embodiments, the connecting conductor further includes a second portion that overlaps with a projection of the first electrode in an orthographic projection of the first surface, and a ratio of a thickness of the first portion to a thickness of the second portion is between 4-10.

[0031] When adopting the above-mentioned embodiment, the thickness of the first part is related to the thickness of the second part. The thicker first part can ensure the reliability of welding, and the thinner second part can realize the electrical transmission of adjacent isotropic fine grids along the extension direction of the connecting conductor, thereby preventing the problem of partial poor joining. A second part that is too thin is not conducive to the transmission of current, and a second part that is too thick will lead to waste of materials. The present application achieves a balance between material cost and electrical transmission effect by setting the thickness ratio to 4-10.

[0032] In some exemplary embodiments, the thickness of the first portion is greater than or equal to 25 micrometers.

[0033] When the above embodiment is adopted, setting the first part thicker is beneficial to maintaining its reliability with the external electrical connector in the welding state, reducing the risk of poor welding, and under the condition of unchanged width, it can also increase the cross-sectional area of ​​the connecting conductor to reduce the resistance of the connecting conductor.

[0034] In some exemplary embodiments, the thickness of the second portion is 5 micrometers to 15 micrometers.

[0035] In the case of the above embodiment, when the thickness of the first part is greater than or equal to 25 microns, the second part should be set to a suitable thickness. If it is set too thin, such as the upper limit value corresponding to the thickness ratio of 10, it is not conducive to the current transmission of two adjacent fine grids; and if it is set too thick, such as the lower limit value corresponding to the thickness ratio of 4, it not only wastes the material of the connecting conductor, but also has little improvement on electrical conduction, and may cause the connecting conductor to extend in the width direction during printing, and then cause overlap with another opposite fine grid to cause a short circuit.

[0036] In some exemplary embodiments, the connecting conductor further includes a third portion that coincides with a projection of the insulating layer in an orthographic projection of the first surface; and a thickness of the first portion is greater than a thickness of the third portion.

[0037] In the case of the above-mentioned embodiment, the first part is used as the main connection point between the connecting conductor and the external electrical connector. Setting it thicker is beneficial to making the joint position with the electrical connector have better welding quality; correspondingly, the third part is not particularly thick, which can make the surface of the connecting conductor roughly flush, so as to reduce the warping deformation of the electrical connector after lamination.

[0038] In some exemplary embodiments, a portion of the battery body located between adjacent first electrodes and second electrodes forms an isolation region; the insulating layer covers the isolation region and extends onto the second electrode.

[0039] In the case of the above embodiment, under the premise that the width of the battery body is limited, the wider the width of the first electrode and the second electrode is set, the smaller the distance between the first electrode and the second electrode in the first direction. To this end, an insulating layer is used to cover the entire isolation area and extend onto the second electrode, which can be used to maintain the insulation between the first electrode and the second electrode along the first direction and prevent the connecting conductor from entering the isolation area to avoid leakage caused by excessive electric field strength in the isolation area.

[0040] An embodiment of the present invention further provides a photovoltaic module, comprising: a back contact cell; and an electrical connector for electrically connecting connecting conductors of at least two of the back contact cells.

[0041] In the above embodiment, the electrical connector electrically connects a connection conductor of one polarity of a back contact battery and electrically connects a connection conductor of another polarity of another back contact battery, so that multiple back contact batteries can be connected in series to form a battery string.

[0042] In some exemplary embodiments, a bonding layer is provided between the electrical connector and the connecting conductor, and the bonding layer is continuous along an extending direction of the electrical connector.

[0043] According to the above embodiment, the bonding layer and the first portion of the connection conductor form a good connection and electrical connection relationship.

[0044] In some exemplary embodiments, an air gap is formed between the bonding layer and the third portion of the connecting conductor.

[0045] In the case of the above embodiment, since the bonding layer has formed a good connection and electrical connection relationship at the first part of the connecting conductor, the part forming the air gap may not be connected to the third part, which is conducive to reducing the amount of material used to form the bonding layer.

[0046] In some exemplary embodiments, a plurality of first joining portions are disposed between the electrical connector and the connecting conductor, and the plurality of first joining portions are disposed at intervals along the first direction.

[0047] When the above embodiment is adopted, the plurality of first joining portions arranged at intervals are beneficial to reducing the amount of material used to form the first joining portions.

[0048] In some exemplary embodiments, the first joining portion is disposed on the first portion of the connecting conductor.

[0049] When adopting the above-mentioned embodiment, the first bonding part is mainly arranged on the first part so that the bonding layer is discrete and discontinuous in the first direction. This not only plays the role of reducing the amount of material used to form the bonding layer, but also prevents short circuit problems caused by excessive or improper distribution of the bonding layer.

[0050] In some exemplary embodiments, the photovoltaic assembly includes a second bonding portion, and the second bonding portion is located on at least two first electrodes.

[0051] In the case of the above embodiment, the second bonding portion is continuously disposed on at least two first electrodes and on the second electrode between the two first electrodes, which is conducive to forming a better electrical connection with the connecting conductor and the electrical connector and helps to reduce the contact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a schematic diagram of a top view of a back contact battery according to an exemplary embodiment of the present invention;

[0053] Figure 2 yes Figure 1 A partial cross-sectional view of the portion A1-A2 of the illustrated exemplary embodiment;

[0054] Figure 3 is a schematic diagram of a back contact battery according to another exemplary embodiment of the present invention from a top view;

[0055] Figure 4 is a schematic diagram of a back contact battery according to another exemplary embodiment of the present invention from a top view;

[0056] Figure 5 yes Figure 1 A partial cross-sectional view of the B1-B2 portion of the illustrated exemplary embodiment;

[0057] Figure 6 is a partial cross-sectional view of a photovoltaic assembly according to an exemplary embodiment of the present invention, showing a first joint portion;

[0058] Figure 7 is a partial cross-sectional view of a photovoltaic module according to another exemplary embodiment of the present invention, showing a second bonding portion.

[0059] In the drawings, the meanings of the reference numerals are as follows:

[0060] 1. Battery body;

[0061] 2. a second electrode;

[0062] 3. a first electrode;

[0063] 4. Insulation layer;

[0064] 5. Connect the conductor;

[0065] 51, first protrusion;

[0066] 6. Electrical connectors;

[0067] 7. Bonding layer;

[0068] 71. a first joint;

[0069] 72. second joint portion;

[0070] 8. Air gap. DETAILED DESCRIPTION

[0071] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0072] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0073] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0074] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0075] The different doping areas on the backlight surface of the back contact cell (BC cell) are alternately distributed in sequence. Correspondingly, the sub-grids arranged on different doping areas are also alternately distributed and have different conductivity types. In order to collect the current collected by the sub-grid, some back contact cells will also be provided with a main grid (Busbar) intersecting with the sub-grid. In addition to being connected to the sub-grid of the same polarity, the arranged main grid also needs to cross the sub-grids of different polarities. For this reason, the main grid needs to be electrically isolated from the sub-grids of different polarities.

[0076] At present, there are two main ways to electrically isolate the main grid from the auxiliary grids of different polarities. One is to set the auxiliary grid to a discontinuous structure so that the main grid passes through the disconnected portion formed by the auxiliary grids of different polarities. The other is to use an auxiliary grid with a continuous structure and set an insulating layer between the overlapping portions of the main grid and the auxiliary grids of different polarities.

[0077] The latter method can more effectively avoid electrical contact between sub-grids of different polarities than the former, which is beneficial to reducing short-circuit current and leakage current. Based on the material characteristics of the material used for the insulating layer (such as insulating glue, silicon oxide, silicon nitride or other materials), the surface of the insulating layer is smooth, and the middle part is more convex than the two sides. In this way, it is beneficial to make the part of the main grid located between two adjacent insulating layers thicker than the part located on the insulating layer, but the surface of the part above the insulating layer that is away from the battery body often forms a relatively smooth curved surface, which is not conducive to forming an effective connection with the external interconnection strip through solder.

[0078] In view of this, how to provide a back-contact cell and photovoltaic module that is conducive to effectively connecting the main grid with external interconnection bars has become a technical problem that needs to be solved urgently.

[0079] Figure 1 is a schematic diagram of a top view of a back-contact battery according to an exemplary embodiment of the present invention. Figure 2 yes Figure 1 A partial cross-sectional view of the portion A1-A2 of the exemplary embodiment shown.

[0080] According to the back contact battery provided by the present invention, Figure 1 and Figure 2 As shown, the back contact cell of the present invention can be a traditional IBC cell (interdigitated back contact cell), or 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 therein is a different passivation material, for example, it can be a combination of polycrystalline silicon passivation and amorphous / microcrystalline passivation).

[0081] The above-mentioned back contact battery includes a battery body 1, which includes at least a substrate and a doping layer on the substrate, wherein the substrate is a rectangular or square structure, and its long side or side length is between 182-240 mm, preferably (182±2)*(191±2) mm, (182±2)*(210±2) mm, (210±2)*(210±2) mm.

[0082] The cell body 1 of the above-mentioned IBC cell (interdigitated back contact cell) includes a first doped semiconductor portion and a second doped semiconductor portion arranged alternately and spaced along a first direction on a substrate to form an interdigitated doped portion structure. One of the first doped semiconductor portion and the second doped semiconductor portion is n-type doped, and the other is p-type doped, and the first doped semiconductor portion and the second doped semiconductor portion are respectively provided with spaced electrode structures.

[0083] The cell body 1 of the above-mentioned TBC cell (TOPCon back contact cell) includes a tunneling oxide layer disposed on a substrate, and a first doped semiconductor portion and a second doped semiconductor portion formed by a doped polysilicon layer. The TOPCon structure formed by the stacked tunneling oxide layer and the doped polysilicon layer can provide a higher carrier lifetime and lower surface recombination for the TBC cell than the IBC cell, which is beneficial to improving the photoelectric conversion efficiency of the TBC cell.

[0084] The battery body 1 of the above-mentioned HBC battery (heterojunction back contact battery) includes an n-type doping layer and a p-type doping layer stacked on a substrate to form a heterojunction structure. Among them, the n-type doping layer includes but is not limited to microcrystalline silicon or amorphous silicon (to provide electrons), and the p-type doping layer can also use microcrystalline silicon or amorphous silicon (such as using boron as a dopant to provide holes). HBC batteries help to improve the carrier lifetime and reduce surface recombination. Furthermore, a conductive oxide layer (i.e., TCO) can be set between the surface of the n-type doping layer and the p-type doping layer and the electrode, which is beneficial to collect carriers in the doping area and can also play a certain anti-reflection role.

[0085] The battery body 1 of the hybrid back contact battery can adopt a layer structure similar to that of an IBC battery or a TBC battery, and configure a corresponding passivation layer structure thereon, such as a combination of at least two of polycrystalline silicon passivation, amorphous silicon passivation and microcrystalline silicon passivation.

[0086] Based on the back contact battery of any of the above embodiments, the back contact battery further includes a first surface of the battery body 1 (such as the backlight surface of the battery body 1, i.e. Figure 1The first electrode 3, the second electrode 2 and the connecting conductor 5 are arranged on the surface facing the viewing angle as shown; the corresponding second surface is the light-receiving surface. The first electrode 3 and the second electrode 2 (also called fine grid, collector grid line, auxiliary grid, etc., the first electrode 3 and the second electrode 2 have different polarities, and are respectively used to extract majority carriers or minority carriers from different doping regions), the first electrode 3 and the second electrode 2 are arranged along the first direction (such as Figure 1 The upper and lower directions shown in FIG. 1 are arranged alternately in sequence, and along the second direction (as shown in FIG. Figure 1 The first direction extends in the left-right direction as shown, and the first direction intersects the second direction.

[0087] The connecting conductor 5 (which may be called a main grid in some cases and is used to gather the current collected by the first electrode 3 or the second electrode 2) extends along the first direction, an insulating layer 4 is provided between the connecting conductor 5 and the first electrode 3, and the connecting conductor 5 is connected to the second electrode 2. The connecting conductor 5 includes a first portion located between two insulating layers 4 adjacent to each other along the first direction and a second portion that coincides with the projection of the first electrode 3 in the orthographic projection of the first surface, the surface of the first portion that faces away from the battery body 1 has a first average roughness, and the surface of the second portion that faces away from the battery body 1 has a second average roughness, wherein the second average roughness is less than the first average roughness.

[0088] It should be noted that the average roughness refers to the average roughness of the sample length (e.g. Figure 2 The average distance of the profile near the outside of the cell (near the connector) deviating from the reference line (the base reference line of multiple protrusions) in the N part shown in the figure is used to reflect the overall roughness level of the surface. The larger the average roughness value, the rougher the surface, the smaller the surface undulations, and the better the flatness. When measuring specifically, it is necessary to Figure 2 The values ​​of points at 20 different positions on a sampling length of at least 50 μm continuously on the cross-sectional graph in the figure are tested and the average value is calculated.

[0089] In an illustrative embodiment, taking the battery body 1 with n-type silicon as the substrate as an example, the first electrode 3 is arranged on the n-type doping region, and the corresponding second electrode 2 is arranged on the p-type doping region. Corresponding to the corresponding doping region, the first electrode 3 is used as the positive electrode of the back contact battery, and the second electrode 2 is used as the negative electrode of the back contact battery. Similarly, the first electrode 3 can also be arranged on the p-type doping region to serve as the negative electrode, and the second electrode 2 can also be arranged on the n-type doping region to serve as the positive electrode.

[0090] In an illustrative embodiment, Figure 1As shown, the insulating layer 4 includes but is not limited to an insulating block configured as a roughly rectangular shape. In detail, the width of the insulating block should be configured to be greater than the width of the connecting conductor 5, so that the portion of the connecting conductor 5 that overlaps with the first electrode 3 in the orthographic projection direction of the battery body 1 is completely covered to electrically isolate the connecting conductor 5 and the first electrode 3. Among them, the insulating layer 4 can be made of inorganic materials, such as silicon oxide, silicon nitride, etc., and can also be made of organic materials, such as insulating glue, etc. The thickness of the insulating layer 4 is not greater than 60μm, for example, it can be 20μm, 30μm, 40μm, 50μm, 60μm, etc. Its thickness is not easy to be too large to prevent the first part from being too low, causing poor welding, or requiring more connecting conductor material to offset the height difference.

[0091] In an illustrative embodiment, Figure 1 As shown, a plurality of insulating small blocks (ie, insulating layer 4) are disposed on the first electrode 3. In detail, the plurality of insulating small blocks on each first electrode 3 are arranged along a first direction (eg Figure 1 The connecting conductor 5 and each first electrode 3 are arranged at intervals in the up-down direction (as shown) so as to be set at a position where the connecting conductor 5 and each first electrode 3 are stacked.

[0092] In an illustrative embodiment, Figure 2 As shown, the insulating block located on the first electrode 3 often forms a roughly arched cross-sectional shape (i.e., the middle portion located on the first electrode 3 is convex upward, and the edge portions located on both sides of the middle portion are thinner). Figure 2 The insulating layer 4 extends in the left and right directions as shown in the figure, and is formed on the insulating layer 4 and between adjacent insulating layers 4. Figure 2 FIG. 4 only schematically shows that the connecting conductor 5 spans across two insulating layers 4 . It should be understood that the connecting conductor 5 may span across each insulating layer 4 arranged along the first direction.

[0093] In an illustrative embodiment, Figure 2 As shown, on the first surface of the battery body 1 (such as Figure 2 In the orthographic projection of the upper surface shown in FIG. 1 , the second portion (such as the upper surface shown in FIG. 1 ) of the connecting conductor 5 that overlaps with the first electrode 3 Figure 2 The M portion shown in FIG. 4 is a portion of the battery body 1 that is away from the surface of the insulating layer 4 (eg Figure 2 The slope of the upper surface shown in FIG. 1 also forms a curved surface accordingly. In detail, the second average roughness of the second portion (i.e., Ra2, which is the curved surface roughness) is less than the first average roughness (i.e., Ra1), that is, the second portion is smoother than the first portion, has less surface undulations, and has better flatness. Preferably, the concave-convex structure formed by the second portion should be more uniform than that of the first portion, and the largest convex portion should also be smaller. In this way, it is helpful to prevent the second portion from piercing the insulating layer 4 when the connecting conductor 5 is welded or laminated with an external electrical connector (such as a welding strip), thereby avoiding leakage and short circuit.

[0094] In such an embodiment, the second average roughness is configured to be smaller than the first average roughness, that is, the second portion is smoother than the first portion. The relatively rough first portion is conducive to the solder (including but not limited to solder paste) adhering to the connecting conductor 5 and forming a larger contact area, so as to more effectively reduce the contact resistance; in addition, when welding with an external electrical connection member (such as a welding strip), it is also helpful to form a larger area of ​​an intermetallic compound layer (i.e., IMC) to provide a greater pull-out resistance and have a better welding quality.

[0095] Figure 3 is a schematic diagram of a top view of a back-contact battery according to another exemplary embodiment of the present invention.

[0096] In another exemplary embodiment, Figure 3 As shown in FIG. 1 , a battery structure without a main grid is partially shown. Specifically, the battery body 1 includes a C region located at the edge (such as Figure 3 The upper and lower regions of the battery body 1 as shown), and the D region in the middle (as shown Figure 3 The area between the two C areas shown in the figure) is provided with a connecting conductor 5 in the C area of ​​the battery body 1 to serve as a terminal main grid. The configuration of the connecting conductor 5 and the first electrode 3, the second electrode 2 and the insulating layer 4 is similar to that of the aforementioned embodiment and will not be repeated here. The portion of the battery body 1 located in the D area is not provided with a connecting conductor 5 so that the area forms a completely main grid-free structure. Generally speaking, along the extension direction of the connecting conductor 5, the width of the C area is much smaller than the width of the D area, wherein, in a single C area, the length of the connecting conductor 5 along its extension direction can be 3-12 mm.

[0097] In such an embodiment, the connection conductor 5 is provided only at the edge of the battery body 1 for connecting with the electrical connector (such as a welding strip). In this way, the edge current of the battery body 1 can be collected by the connection conductor 5 to prevent hidden cracks caused by the junction position of the electrical connector and the electrode (i.e., the first electrode and the second electrode) being too close to the edge of the battery body 1.

[0098] In another exemplary embodiment, not shown in the figure, the back contact battery illustrated in the present invention may be a battery structure without a main grid (i.e., 0BB). In detail, the first electrode 3 and the second electrode 2 (also called fine grid, collector grid line, auxiliary grid, etc., the first electrode 3 and the second electrode 2 have different polarities, respectively used to extract majority carriers or minority carriers in different doping regions) on the first surface of the battery body 1 are directly connected to an external electrical connector (also called welding strip or interconnection strip, used to connect at least two back contact batteries in series) without passing through the main grid. At this time, the connecting conductor 5 can be regarded as a bonding layer connecting the welding strip or can also be regarded as a main grid structure connecting the first electrode 3 or the second electrode 2.

[0099] On this basis, the connecting conductor 5 is arranged between the first electrode 3 or the second electrode 2 and the electrical connector, which can be used as a bonding layer (it can be solder, solder paste, such as solder, used to weld the auxiliary grid and the welding strip; it can also be a conductive adhesive layer, such as conductive silver paste, conductive glue, etc., used to conductively bond the auxiliary grid and the welding strip) to form a good welding relationship between the electrode (i.e., the first electrode 3 or the second electrode 2) and the electrical connector.

[0100] The connecting conductor 5 is prefabricated at a specific position of the battery body 1. Furthermore, during the welding process of the electrode and the electrical connector, the electrical connector has a bonding layer, which melts and bonds with the connecting conductor 5 and dissolves mutually to form an intermetallic compound (ie, IMC).

[0101] According to an embodiment of the present invention, Figure 2 As shown, the first average roughness is greater than or equal to 5 microns.

[0102] According to an embodiment of the present invention, Figure 2 As shown, the second average roughness is less than 10 microns. In an exemplary embodiment, as Figure 2 As shown, the first portion (eg, Figure 2 The N portion shown in FIG. 1 is away from the surface of the battery body 1 (eg Figure 2 The upper surface shown in FIG. 1 forms a roughly curved surface. In detail, the first average roughness of the surface (i.e., Ra1, which is the curved surface roughness) includes but is not limited to being configured to be greater than or equal to 5 microns, i.e., Ra1 ≥ 5 μm. Further, the largest convex portion in the first portion (i.e., portion N) includes but is limited to being greater than or equal to 8 microns. It should be understood that the embodiments of the present invention are not limited thereto.

[0103] For example, the surface of the first portion facing away from the battery body 1 may 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 or any other average roughness greater than 5 μm to meet corresponding welding and electrical requirements.

[0104] In an illustrative embodiment, in order to form the connection conductor 5 having the above-mentioned first average roughness, an organic component having a weight component greater than 5% (and containing 2%-5% epoxy resin) may be configured in the paste (such as silver paste) for printing the main grid, and then sintered at 500-800°C. During the sintering process, due to the decomposition and overflow of the organic material, the surface of the formed connection conductor may present a rough surface, that is, a roughness of more than 5 microns. It should be understood that the embodiments of the present invention are not limited thereto.

[0105] For example, it can also be achieved by other processes such as scraping and spraying. In such an embodiment, by setting the first average roughness of the first part (i.e., part N) of the connecting conductor 5 to be greater than or equal to 5 microns, the first part can form a relatively rough surface. In this way, it is beneficial to form a larger contact area when the connecting conductor is welded with an external electrical connector or solder, so as to more effectively reduce the contact resistance, and to help form a larger area of ​​the intermetallic compound layer to provide greater tensile resistance. By configuring the second roughness to be less than 10 microns, the convex portion formed on the surface of the second part can be smaller to avoid the situation of piercing the insulating layer due to the convex portion protruding too much from the surface. For example, the surface of the second part away from the battery body 1 can also be configured as 1μm, 2μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 9μm and any other average roughness less than 10μm, but at the same time it is necessary to ensure that it is less than the average roughness of the surface of the first part away from the battery body 1.

[0106] According to an embodiment of the present invention, Figure 2 As shown, the surface of the first portion facing away from the first surface (such as Figure 2 The upper surface shown in FIG. 1 has a plurality of first protrusions 51, and the maximum height of the plurality of first protrusions 51 along a direction perpendicular to the first surface is greater than or equal to 8 microns.

[0107] According to an embodiment of the present invention, Figure 2 As shown, the ratio of the thickness of the first portion to the thickness of the second portion is between 4-10.

[0108] In such an embodiment, the first protrusion 51 formed on the first part has a relatively large height, which helps to improve the bonding force between the electrical connector and the connecting conductor, increase the contact area, and reduce the contact resistance. The thickness of the first part is related to the thickness of the second part. If it is too thin, it is not conducive to the transmission of current, and if it is too thick, it leads to a waste of materials.

[0109] According to an embodiment of the present invention, Figure 2 As shown, the thickness of the first portion is greater than or equal to 25 microns.

[0110] In such an embodiment, setting the first part thicker is beneficial to maintaining its reliability with the external electrical connector in the welding state, reducing the risk of poor welding, and under the condition of unchanged width, it can also increase the cross-sectional area of ​​the connecting conductor to reduce the resistance of the connecting conductor.

[0111] According to an embodiment of the present invention, Figure 2 As shown, the thickness of the second portion is 5 micrometers to 15 micrometers.

[0112] According to an embodiment of the present invention, Figure 2 As shown, the connecting conductor 5 also includes a third portion that coincides with the projection of the insulating layer 4 in the orthographic projection of the first surface. The thickness of the first portion is greater than that of the third portion (e.g. Figure 2 The thickness of the O part is shown.

[0113] According to an embodiment of the present invention, Figure 2 As shown, the third part (such as Figure 2 The thickness of the third portion (shown as the O portion) is less than or equal to 25 microns. The width of the third portion along the first direction is 300-800 microns, that is, the width of each insulating layer 4 along the first direction is 300-800 microns, thereby achieving insulation of the opposite-sex electrodes, while ensuring that the spacing between the two insulating layers 4 in the first direction can expose the same-sex electrodes to be connected to the conductor 5, wherein the spacing between the two insulating layers 4 in the first direction is 100-500 microns, that is, the width of the first portion is 100-500 microns.

[0114] In an illustrative embodiment, Figure 2 As shown, the first part (such as Figure 2 The surface of the battery body 1 (as shown in the N part) away from the battery body 1 Figure 2 The upper surface shown in FIG. 1 is not smooth, and therefore, the thickness of the first portion can be understood as the average thickness of the first portion. Further, the third portion (such as FIG. 1 ) where the connecting conductor 5 overlaps with the insulating layer 4 Figure 2 The O portion shown in FIG. 1 includes a second portion (such as Figure 2 The M part shown in the figure), the second part has a thickness (even if the connecting conductor 5 will not be disconnected in the second part), and the thickness of the third part gradually increases from the upper surface of the insulating layer 4 to both sides. For this reason, the thickness of the third part can also be understood as the average thickness of the third part. The average thickness refers to the average value of the thickness of the corresponding layer in the region along the direction perpendicular to the surface of the battery, which should at least ensure the average thickness value of multiple thicknesses in the middle position and multiple thicknesses at the boundary connected to the first part.

[0115] According to an embodiment of the present invention, Figure 1 and Figure 2As shown, the width of the first electrode 3 is 30 micrometers to 100 micrometers. And / or, the width of the second electrode 2 is 30 micrometers to 100 micrometers.

[0116] In such an embodiment, setting the width of the first electrode 2 and the second electrode 3 to be narrower helps to improve the fill factor and output power of the back contact battery, and helps to optimize the current flow path to reduce current congestion and potential loss points.

[0117] In such an embodiment, setting the first part thicker is beneficial to maintaining the reliability of the external electrical connector in the welding state, reducing the risk of poor welding, and under the condition of unchanged width, the cross-sectional area of ​​the connecting conductor can also be increased to reduce the resistance of the connecting conductor. In the case of the above embodiment, for the thickness of the first part greater than or equal to 25 microns, the second part should be set to a suitable thickness. If it is set too thin, such as corresponding to the upper limit value of the thickness ratio of 10, it is not conducive to the current transmission of two adjacent fine grids; and if it is set too thick, such as corresponding to the lower limit value of the thickness ratio of 4, it not only wastes the material of the connecting conductor, but also has little improvement on electrical conduction, and may cause the connecting conductor to extend in the width direction during printing, which then leads to overlapping with another opposite fine grid to cause a short circuit.

[0118] In an exemplary embodiment, the first electrode 3 and the second electrode 2 can be formed by printing methods such as silk screen printing. Figure 1 and Figure 2 As shown, at this time, the width of the first electrode 3 and the second electrode 2 can be 30 microns to 100 microns. In detail, the first electrode 3 is arranged on the majority carrier doping region, and the second electrode 2 is arranged on the minority carrier doping layer. Further, the width of the first electrode 3 (i.e., w1) is configured to be smaller than the width of the second electrode 2 (i.e., w2), that is, 30μm≤w1≤100μm, 30μm≤w2≤100μm, and w1<w2.

[0119] In such an implementation, taking the battery body with n-type silicon wafer as the 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; accordingly, the n-type doped region is used as a majority carrier region for collecting majority carriers, i.e., electrons. Based on the characteristics of the back contact battery, when the minority carriers are collected by the second electrode 2, the holes will also be transmitted laterally in the substrate. In this process, holes are prone to carrier recombination with majority carriers in the majority carrier region. For this reason, the second electrode 2 located in the minority carrier doped region is set wider, which can effectively improve the collection efficiency of the second electrode 2 for minority carriers.

[0120] In an illustrative embodiment, the first electrode 3 and the second electrode 2 can be directly electrically connected to the corresponding doped region, or a transparent conductive oxide (TCO) layer can be provided between the electrode (i.e., the first electrode 3 and the second electrode 2) and the corresponding doped region. Based on the collection efficiency of minority carriers as described above, the minority carrier doped region and / or the transparent conductive oxide layer located on the minority carrier doped region can be designed to be wider to further improve the collection efficiency of minority carriers. The first electrode 3 and / or the second electrode 2 are formed on the battery body 1 including but not limited to electroplating, evaporation, vapor deposition, etc.

[0121] Similarly, if the battery body with a p-type silicon wafer as the substrate is taken as an example, electrons are minority carriers and holes are majority carriers. For this reason, the electrode located on the minority carrier doping region should also be set wider, and the specific effect will not be repeated. It should be understood that the embodiments of the present invention are not limited to this.

[0122] For example, the widths of the first electrode 3 and the second electrode 2 may be set to be substantially equal.

[0123] For another example, the width of the first electrode 3 may be set to be greater than the width of the second electrode 2. Specifically, it should be preferably to meet the corresponding requirements for collecting photogenerated carriers, and will not be elaborated here.

[0124] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, a portion of the battery body 1 located between the adjacent first electrode 3 and second electrode 2 forms an isolation region. The insulating layer 4 covers a portion of the isolation region.

[0125] In an illustrative embodiment, Figure 2 As shown, the portion between the first electrode 3 and the second electrode 2 along the first direction forms an isolation region. In detail, the insulating layer 4 extends from the upper portion of the first electrode 3 to the isolation region, and is spaced apart from the second electrode 2. The portion between the insulating layer 4 and the second electrode is covered by the connecting conductor 5 (the covered portion is only the area within the width of the connecting conductor 5) to maintain the insulation effect between the first electrode 3 and the second electrode 2 (and the connecting conductor 5), while reserving a sufficient width to ensure that the connecting conductor can fully contact the second electrode. Figure 4 is a schematic diagram of a top view of a back-contact battery according to another exemplary embodiment of the present invention. Figure 5 yes Figure 1 A partial cross-sectional view of the B1 - B2 portion of the exemplary embodiment shown.

[0126] According to an embodiment of the present invention, the first electrode 3 and the second electrode 2 may be formed by a deposition process such as electroplating. Figure 4 and Figure 5As shown, at this time, the width of the first electrode 3 is 300 micrometers to 600 micrometers. And / or, the width of the second electrode 2 is 300 micrometers to 600 micrometers.

[0127] In an illustrative embodiment, Figure 4 and Figure 5 As shown, the width of the first electrode 3 and the second electrode 2 can both be 300 microns to 600 microns. In detail, the first electrode 3 is disposed on the majority carrier doping region, and the second electrode 2 is disposed on the minority carrier doping layer. Further, the width of the first electrode 3 (i.e., w1) is configured to be smaller than the width of the second electrode 2 (i.e., w2), i.e., 300μm≤w1≤600μm, 300μm≤w2≤600μm, and w1<w2. Further, the first surface (e.g., Figure 4 The sum of the areas of the first electrode 3 and the second electrode 2 used on the surface facing the viewing angle shown in the figure includes but is not limited to 50% or more of the total area of ​​the first surface.

[0128] In this embodiment, the width of the second electrode 2 is set wider, and the technical effect produced is the same as the above Figure 1 and Figure 2 The embodiments shown are similar in that the electrode (ie, the second electrode 2 ) located on the minority carrier doping region is set wider to improve the collection effect of minority carriers.

[0129] In such an embodiment, the first surface is the backlit surface of the back contact battery, so there is no need to consider its shading loss. On this basis, by increasing the width of the first electrode 3 and the second electrode 2 and the area ratio of the first surface, the current collection efficiency can be effectively improved, especially the collection efficiency of minority carriers on the minority carrier doping region. In addition, the provision of a wider electrode can also increase its cross-sectional area, which can effectively reduce the series resistance. In addition, the wider first electrode 3 and the second electrode 2 can also distribute the electric field more evenly, and provide support for the battery body 1, which is still beneficial to improve the structural strength of the battery body.

[0130] According to an embodiment of the present invention, Figure 4 and Figure 5 As shown, the portion of the battery body 1 located between the adjacent first electrode 3 and the second electrode 2 forms an isolation region. The insulating layer 4 covers the isolation region and extends onto the second electrode 2.

[0131] Under the premise that the width of the battery body 1 is limited, the width of the first electrode 3 and the second electrode 2 is set wider, so that the distance between the first electrode 3 and the second electrode 2 in the first direction is smaller. To this end, the insulating layer 4 is used to cover the entire isolation area and extend onto the second electrode 2, which can be used to maintain the insulation between the first electrode 3 and the second electrode 2 along the first direction and prevent the connecting conductor 5 from entering the isolation area, so as to avoid leakage caused by excessive electric field strength in the isolation area.

[0132] In an illustrative embodiment, Figures 1 to 5 As shown, the back contact cell further includes a fourth electrode (also called a main grid), which extends along the first direction and is connected to the connecting conductor 5 along the second direction (such as Figure 1 The fourth electrode and the connecting conductor 5 are arranged alternately and spaced apart (in the left and right directions shown in the figure), and the fourth electrode and the connecting conductor 5 have different polarities. In detail, the fourth electrode is connected to the first electrode 3 and is used to collect the current collected by the first electrode 3. Further, an insulating layer 4 is also correspondingly arranged between the fourth electrode and the second electrode 2, and the portion of the fourth electrode located between two adjacent insulating layers 4 also forms a first part and a second part accordingly. Among them, the first part and the second part of the fourth electrode can adopt an implementation similar to that of the connecting conductor 5 and have similar effects, so they are not repeated here.

[0133] According to the back contact battery provided by the present invention, Figure 1 and Figure 2 As shown, the battery body 1 includes a battery body 1, a first electrode 3, a second electrode 2 and a connecting conductor 5. The battery body 1 has a first surface opposite to the battery body 1 (i.e., the backlight surface of the battery body 1). Figure 1 The first electrode 3 and the second electrode 2 (also called fine grid, collector grid line, auxiliary grid, etc., the first electrode 3 and the second electrode 2 have different polarities and are used to extract majority carriers or minority carriers from different doping regions respectively) are arranged on the first surface of the battery body 1. The first electrode 3 and the second electrode 2 are arranged along the first direction (such as Figure 1 The connecting conductors 5 are arranged alternately and spaced in sequence and extend along the second direction. The connecting conductors 5 are arranged on the first surface and extend along the first direction (as shown in the upper and lower directions). Figure 1 The connecting conductor 5 extends in the left-right direction as shown, an insulating layer 4 is arranged between the connecting conductor 5 and the first electrode 3, and is connected to the second electrode 2. The connecting conductor 5 includes a first portion (such as Figure 2 As shown in the N part, the surface of the first part facing away from the battery body 1 has a plurality of first protrusions 51, and the maximum height of the plurality of first protrusions 51 is greater than or equal to 8 microns.

[0134] In such an embodiment, the first protrusion 51 formed on the first portion has a relatively large height, which helps to enhance the joining force between the electrical connector 6 and the connecting conductor 5 , increase the contact area, and reduce the contact resistance.

[0135] According to an embodiment of the present invention, Figure 2 As shown, the connecting conductor 5 also includes a second portion (such as Figure 2 M part shown), the ratio of the thickness of the first part to the thickness of the second part is between 4-10.

[0136] In such an embodiment, the thickness of the first part is related to the thickness of the second part. If it is too thin, it is not conducive to the transmission of current, and if it is too thick, it leads to waste of materials.

[0137] In addition, as an independent embodiment, Figure 2 As shown, the connecting conductor 5 also includes a second portion (such as Figure 2 M part shown), the ratio of the thickness of the first part to the thickness of the second part is between 4-10. When the above-mentioned independent embodiment is adopted, without considering the roughness of the connecting conductor 5 or the maximum protrusion height (of course, other contents of the embodiment of the present invention can be generally applied to the independent embodiment), the thickness of the first part and the thickness of the second part are related, the thicker first part can ensure the reliability of welding, and the thinner second part can realize the electrical transmission of adjacent isotropic fine grids along the extension direction of the connecting conductor, and prevent the problem of partial poor bonding. If the second part is too thin, it is not conducive to the transmission of current, and if it is too thick, it leads to waste of materials. The present application achieves a balance between material cost and electrical transmission effect by setting the thickness ratio to 4-10.

[0138] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the thickness of the first part is greater than or equal to 25 microns. Its height can be slightly less than the height of the insulating layer 4, but it should not be too low to prevent the soldering strip from being unable to obtain a reliable connection even through the bonding layer. Generally speaking, the height difference between the lowest position of the first part and the highest position of the insulating layer 4 is between 10-50 microns, thereby achieving a better connection with the soldering strip on the basis of less connecting conductor material.

[0139] In such an embodiment, setting the first part thicker is beneficial to maintaining the reliability of the external electrical connector in the welding state, reducing the risk of poor welding, and under the condition of unchanged width, the cross-sectional area of ​​the connecting conductor can also be increased to reduce the resistance of the connecting conductor. In the case of the above embodiment, for the thickness of the first part greater than or equal to 25 microns, the second part should be set to a suitable thickness. If it is set too thin, such as corresponding to the upper limit value of the thickness ratio of 10, it is not conducive to the current transmission of two adjacent fine grids; and if it is set too thick, such as corresponding to the lower limit value of the thickness ratio of 4, it not only wastes the material of the connecting conductor, but also has little improvement on electrical conduction, and may cause the connecting conductor to extend in the width direction during printing, which then leads to overlapping with another opposite fine grid to cause a short circuit.

[0140] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the thickness of the second portion is 5 micrometers to 15 micrometers.

[0141] In such an embodiment, for the thickness of the first part being greater than or equal to 25 microns, the second part should be set to a suitable thickness. If it is set too thin, such as the upper limit value corresponding to the thickness ratio of 10, it is not conducive to the current transmission of two adjacent fine grids; and if it is set too thick, such as the lower limit value corresponding to the thickness ratio of 4, it not only wastes the material of the connecting conductor, but also has little improvement on the electrical conduction, and may cause the connecting conductor to extend in the width direction during printing, and then cause overlap with another opposite fine grid to cause a short circuit.

[0142] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the connecting conductor 5 also includes a first surface (such as Figure 2 The third part (as shown in the upper surface) of the orthographic projection of the insulating layer coincides with the projection of the insulating layer Figure 2 The first part (as shown in Figure 2 The thickness of the M portion) shown is greater than the thickness of the third portion.

[0143] In such an embodiment, the first part is used as the main connection point between the connecting conductor and the external electrical connector. Setting it thicker is beneficial to making the joint position with the electrical connector have better welding quality; correspondingly, the third part is not particularly thick, which can make the surface of the connecting conductor roughly flush, so as to reduce the warping deformation of the electrical connector after lamination.

[0144] According to an embodiment of the present invention, Figure 4 and Figure 5 As shown, the portion of the battery body 1 located between the adjacent first electrode 3 and the second electrode 2 forms an isolation region; the insulating layer covers the isolation region and extends onto the second electrode 2 .

[0145] In such an embodiment, under the premise that the width of the battery body 1 is limited, the widths of the first electrode 3 and the second electrode 2 are set wider, so that the distance between the first electrode 3 and the second electrode 2 in the first direction is smaller. To this end, the insulating layer 4 is used to cover the entire isolation area and extend onto the second electrode 2, which can be used to maintain the insulation between the first electrode 3 and the second electrode 2 along the first direction and prevent the connecting conductor 5 from entering the isolation area, so as to avoid leakage caused by excessive electric field strength in the isolation area.

[0146] Figure 6 is a partial cross-sectional view of a photovoltaic module according to an exemplary embodiment of the present invention, showing a first joint portion. Figure 7 is a partial cross-sectional view of a photovoltaic module according to another exemplary embodiment of the present invention, showing a second bonding portion.

[0147] Based on the same inventive concept, the present invention also provides a photovoltaic module, such as Figure 6 and Figure 7 As shown, it includes a back contact battery and an electrical connector 6 (also called a solder strip or an interconnection strip, used to connect at least two back contact batteries in series). The electrical connector 6 electrically connects the connection conductors 5 of at least two back contact batteries, and a bonding layer 7 (also called solder, solder paste, such as solder, which is used to fill the connection conductor 5 and the facing surface of the electrical connector 6 in a molten state to form a metal connection with good electrical conductivity) is provided between the electrical connector 6 and the connection conductor 5. Specifically, the electrical connector 6 connects the connection conductor 5 of one polarity (for example, the positive electrode) of a back contact battery, and at the same time connects the connection conductor 5 of another polarity (for example, the negative electrode) of another back contact battery adjacent to it.

[0148] According to an embodiment of the present invention, Figure 6 As shown, a plurality of first bonding portions 71 are arranged between the electrical connector 6 and the connecting conductor 5, and the plurality of first bonding portions 71 are arranged at intervals along the first direction. The plurality of first bonding layers 71 are relatively sparse, and the plurality of first bonding portions 71 are discretely arranged below the electrical connector 6 and are not connected to each other.

[0149] According to an embodiment of the present invention, Figure 6 As shown, the first joint portion 71 is provided at the first portion of the connecting conductor 5 .

[0150] In an illustrative embodiment, Figure 6 As shown, the surface of the electrical connector 6 (i.e., the welding strip) and the connecting conductor 5 facing away from the battery body 1 (i.e., Figure 6 A plurality of first engaging portions 71 are arranged at intervals between the upper surface shown in FIG. Figure 6Only one first joint portion 71 is schematically shown, and it should be understood that one first joint portion 71 may be provided on each first portion of the connection conductor 5. It should be understood that the embodiments of the present invention are not limited thereto.

[0151] For example, a PAD point (also called a pad) may be provided on at least a portion of the first portion of the connection conductor 5, and the width of the PAD may be configured to be greater than the width of other portions of the connection conductor 5, or to form some special shapes, such as a rectangular portion or a diamond portion protruding from the main body of the connection conductor 5 along the second direction. In this way, the contact area between the first bonding portion 71 (i.e., the solder) and the connection conductor 5 is further increased.

[0152] In such an embodiment, the plurality of first joint portions 71 are spaced apart and discretely distributed along the first direction, which is conducive to reducing the consumption of the first joint portions 71. The specific number and position of the first joint portions 71 can be set according to actual welding requirements. In addition to setting the first joint portion 71 on the first portion of the connecting conductor 5, it can also be set on the second portion or the third portion of the connecting conductor 5.

[0153] According to an embodiment of the present invention, Figure 7 As shown, the photovoltaic assembly includes a second bonding portion 72 , and the second bonding portion 72 is located on at least two first electrodes 3 .

[0154] In an illustrative embodiment, Figure 7 As shown, the second bonding portion 72 extends along the first direction to each of the first electrode 3 and the second electrode 2 .

[0155] According to an embodiment of the present invention, Figure 7 As shown, a bonding layer 7 is provided between the electrical connector 6 and the connecting conductor 5, and the bonding layer 7 is continuous along the extension direction of the electrical connector 6. The second bonding portion 72 can be formed by a plurality of first bonding layers 71 arranged relatively densely, and finally melt-connected into one body. Figure 7 The bonding layer 7.

[0156] According to an embodiment of the present invention, Figure 7 As shown, the connection conductor 5 includes a third portion that coincides with the projection of the insulating layer 4 in the orthographic projection of the first surface of the battery body 1 , and an air gap 8 is formed between the bonding layer 7 and the third portion of the connection conductor 5 .

[0157] In an illustrative embodiment, Figure 7As shown, the second joint portion 72 is continuously arranged between the electrical connector 6 (i.e., the soldering strip) and the connecting conductor 5. Wherein, before being pressed by the electrical connector 6, the second joint portion 72 can be discretely arranged on the connecting conductor 5, and then thinned by pressing (the specific pressing method includes but is not limited to using adhesive film bonding, pressing head machine or any other method), and extends along the first direction. In detail, the second joint portion 72 is spaced from the top of the insulating layer and forms an air gap 8. In such an embodiment, since the second joint portion 72 has formed a good connection and electrical connection relationship between the first part and the third part (except the part of the second part) of the first electrode 3, for this reason, the part forming the air gap 8 may not be connected to the third part. In this way, it is beneficial to reduce the amount of the second joint portion 72 (i.e., solder paste).

[0158] In another exemplary embodiment, not shown in the figure, the second joint portion 72 can be continuously arranged on the connecting conductor 5 (such as in the form of a strip) and then after being pressed together, it will basically completely fill the gap between the electrical connector 6 and the connecting conductor 5 (that is, basically no air gap as shown in 6 will be formed). In this way, compared with Figure 6 and Figure 7 The embodiment shown can form a better electrical connection between the electrical connector 6 and the connecting conductor 5, and provide a greater pull-out resistance, but it also consumes more second bonding portion 72 (i.e., solder paste). Therefore, the specific arrangement of the bonding layer 7 should be comprehensively arranged according to the electrical connection performance and pull-out resistance required by the photovoltaic module.

[0159] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only for reference to the drawings and are not intended to limit the scope of protection of the present invention. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present invention.

[0160] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A back contact battery, characterized in that: include: A battery body (1) having a first surface and a second surface opposite to each other; A first electrode (3) and a second electrode (2) are arranged on a first surface of the battery body (1), the first electrode (3) and the second electrode (2) are arranged alternately and spaced in sequence along a first direction and extend along a second direction, the first direction intersecting the second direction; a connecting conductor (5) disposed on the first surface, the connecting conductor (5) extending along the first direction, an insulating layer (4) being disposed between the connecting conductor (5) and the first electrode (3), and connected to the second electrode (2); The connecting conductor (5) comprises a first portion located between two adjacent insulating layers (4) along the first direction and a second portion overlapping with a projection of the first electrode (3) in an orthographic projection of the first surface, wherein a surface of the first portion facing away from the battery body (1) has a first average roughness, and a surface of the second portion facing away from the battery body (1) has a second average roughness, wherein the second average roughness is smaller than the first average roughness.

2. The back contact cell according to claim 1, characterized in that: The first average roughness is greater than or equal to 5 micrometers.

3. The back contact battery according to claim 2, characterized in that: The second average roughness is less than 10 micrometers.

4. The back contact cell according to claim 1, characterized in that: The surface of the first portion facing away from the first surface has a plurality of first protrusions (51), and the maximum height of the plurality of first protrusions (51) along a direction perpendicular to the first surface is greater than or equal to 8 micrometers.

5. The back contact cell according to claim 1, characterized in that: The ratio of the thickness of the first portion to the thickness of the second portion is between 4-10.

6. The back contact cell according to claim 5, characterized in that: The thickness of the first portion is greater than or equal to 25 micrometers.

7. The back contact cell according to claim 6, characterized in that: The second portion has a thickness of 5 micrometers to 15 micrometers.

8. The back contact cell according to claim 1, characterized in that: The connecting conductor (5) further comprises a third portion which coincides with the projection of the insulating layer (4) in the orthographic projection of the first surface; The thickness of the first portion is greater than the thickness of the third portion.

9. The back contact cell according to claim 8, characterized in that: The thickness of the third portion is less than or equal to 25 micrometers.

10. The back contact cell according to claim 1, characterized in that: Along the first direction, the width of the first electrode (3) is 30 micrometers to 100 micrometers; And / or, the width of the second electrode (2) is 30 micrometers to 100 micrometers.

11. The back contact cell according to claim 1 or 10, characterized in that: The portion of the battery body (1) located between the adjacent first electrode (3) and the second electrode (2) forms an isolation region; The insulating layer (4) covers a portion of the isolation region.

12. The back contact cell according to claim 1, characterized in that: The width of the first electrode (3) is 300 micrometers to 600 micrometers; And / or, the width of the second electrode (2) is 300 micrometers to 600 micrometers.

13. The back contact cell according to claim 1 or 12, characterized in that: The portion of the battery body (1) located between the adjacent first electrode (3) and the second electrode (2) forms an isolation region; The insulating layer (4) covers the isolation region and extends onto the second electrode (2).

14. A back contact battery, characterized in that: include: A battery body (1) having a first surface and a second surface opposite to each other; A first electrode (3) and a second electrode (2) are arranged on a first surface of the battery body (1), the first electrode (3) and the second electrode (2) being arranged alternately and spaced in sequence along a first direction and extending along a second direction; a connecting conductor (5) disposed on the first surface, the connecting conductor (5) extending along the first direction, an insulating layer (4) being disposed between the connecting conductor (5) and the first electrode (3), and connected to the second electrode (2); The connecting conductor (5) comprises a first portion located between two adjacent insulating layers (4) along the first direction, the surface of the first portion facing away from the battery body (1) having a plurality of first protrusions (51), and a maximum height of the plurality of first protrusions (51) being greater than or equal to 8 micrometers.

15. The back contact cell according to claim 14, characterized in that The connecting conductor (5) further comprises a second portion which coincides with the projection of the first electrode (3) in the orthographic projection of the first surface, and the ratio of the thickness of the first portion to the thickness of the second portion is between 4 and 10.

16. The back contact cell according to claim 15, characterized in that The thickness of the first portion is greater than or equal to 25 micrometers.

17. The back contact cell according to claim 16, characterized in that: The second portion has a thickness of 5 micrometers to 15 micrometers.

18. The back contact cell according to claim 14, characterized in that The connecting conductor (5) further comprises a third portion which coincides with the projection of the insulating layer (4) in the orthographic projection of the first surface; The thickness of the first portion is greater than the thickness of the third portion.

19. The back contact cell according to any one of claims 14 to 18, characterized in that: The portion of the battery body (1) located between the adjacent first electrode (3) and the second electrode (2) forms an isolation region; The insulating layer (4) covers the isolation region and extends onto the second electrode (2).

20. A photovoltaic module, characterized in that: include: A back contact battery as claimed in any one of claims 1 to 19; An electrical connector (6) electrically connects at least two connection conductors (5) of the back contact cells.

21. The photovoltaic module according to claim 20, characterized in that: A bonding layer (7) is provided between the electrical connection member (6) and the connection conductor (5), and the bonding layer (7) is continuous along the extension direction of the electrical connection member (6).

22. The photovoltaic module according to claim 21, characterized in that: The connecting conductor (5) includes a third portion that coincides with a projection of the insulating layer (4) in an orthographic projection of the first surface of the battery body (1); An air gap (8) is formed between the bonding layer (7) and the third portion of the connecting conductor (5).

23. The photovoltaic module according to claim 20, characterized in that: A plurality of first joining portions (71) are arranged between the electrical connector (6) and the connecting conductor (5), and the plurality of first joining portions (71) are arranged at intervals along a first direction.

24. The photovoltaic module according to claim 23, characterized in that: The first joint portion (71) is arranged on a first portion of the connecting conductor (5).

25. The photovoltaic module according to claim 21, characterized in that: It comprises a second bonding portion (72), wherein the second bonding portion (72) is located on at least two first electrodes (3).

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