Back contact cell, cell assembly and photovoltaic system

Abstract

The utility model relates to the technical field of solar cells, and provides a back contact cell, a cell assembly and a photovoltaic system, a first doping layer of the back contact cell comprises a stacking region and a non-stacking region, and the stacking region comprises a leakage contact region and an insulation contact region. The insulating layer is stacked on the insulating contact region of the first doped layer. The extension part of the second doping layer extends to cover the electric leakage contact region and covers at least part of the electric leakage contact region. The conductive thin film layer is at least stacked and covered on the body part and the non-stacking area, and a plurality of isolation grooves are formed in the conductive thin film layer, so that the conductive thin film layer comprises a plurality of first parts and a plurality of second parts which are insulated and isolated through the isolation grooves. And the first part and / or the second part also extend to at least partial region of the part, corresponding to the electric leakage contact region, of the extension part. Therefore, through the matching optimization design of the first doping layer, the second doping layer, the conductive thin film layer and the insulating layer, the hot spot resistance and efficiency of the back contact cell can achieve a better matching effect.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and particularly to a back-contact battery, a battery module, and a photovoltaic system. Background Art

[0002] Currently, in solar cells, a back-contact battery is a battery in which both the emitter and base contact electrodes are placed on the back (non-light-receiving surface) of the battery. There is no metal electrode shielding on the light-receiving surface of this battery, thus effectively increasing the short-circuit current of the cell.

[0003] In order to improve the efficiency of the back-contact battery, one of the doped layers of the back-contact battery can be set as a polysilicon layer, and the other doped layer can be set as an amorphous silicon layer or a microcrystalline silicon layer, thereby forming a hybrid back-contact battery. However, although it can improve the efficiency of the battery, during the use of the back-contact battery, when an external obstacle blocks the cell, the blocked cell will exhibit a hot spot phenomenon, resulting in an increase in temperature. When the temperature exceeds a certain value, it is likely to cause damage to the module or even lead to a fire.

[0004] In the related art, in order to improve the anti-hot-spot performance of the back-contact battery, two doped layers with different polarities are stacked together in a local area to form a leakage area, deliberately introducing a leakage point. However, in such a technical solution, the matching between the anti-hot-spot performance and the battery efficiency is not considered. Although the anti-hot-spot performance is improved, it is likely to cause a significant reduction in efficiency. Therefore, how to balance the relationship between the anti-hot-spot performance and the conversion efficiency of the hybrid back-contact battery so that the anti-hot-spot performance and the conversion efficiency can reach a better matching effect has become a technical problem studied by those skilled in the art. Summary of the Utility Model

[0005] The present application provides a back-contact battery, a battery module, and a photovoltaic system.

[0006] The present application is implemented as follows. The back-contact battery according to an embodiment of the present application includes:

[0007] A silicon substrate having opposite front and back surfaces, the back surface including a plurality of first pole regions and a plurality of second pole regions arranged alternately along a first direction, both the first pole regions and the second pole regions extending along a second direction, the second direction intersecting the first direction;

[0008] A first passivation layer and a first doped layer sequentially stacked on the first pole region, the surface of the first doped layer facing away from the silicon substrate having a stacked region and a non-stacked region, the stacked region including a leakage contact region and an insulating contact region;

[0009] An insulating layer stacked on the insulating contact region;

[0010] A second passivation layer and a second doping layer that are sequentially stacked on the second pole region, at least a part of the second doping layer includes a body portion that only covers the second pole region and an extension portion that extends onto the stacking region, the extension portion extends onto the leakage contact region and covers at least a part of the leakage contact region; and

[0011] A conductive thin film layer, the conductive thin film layer at least covers and is disposed on the body portion and the non-stacking region, a plurality of isolation grooves are formed on the conductive thin film layer, the isolation grooves extend along the second direction, so that the conductive thin film layer includes a plurality of first portions and a plurality of second portions that are insulated and isolated by the isolation grooves, the first portions are stacked and cover the body portion, and the second portions are stacked and cover the non-stacking region;

[0012] The first portion and / or the second portion further extend onto at least a part of the region corresponding to the leakage contact region of the extension portion.

[0013] In some embodiments, the first passivation layer is a tunneling oxide layer, and the first doping layer is a doped polysilicon layer;

[0014] The second passivation layer is at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer, and the second doping layer is at least one of a doped amorphous silicon layer and doped microcrystalline silicon.

[0015] In some embodiments, the extension portion includes a leakage contact segment and an insulating contact segment, the leakage contact segment is stacked and covers the leakage contact region, the insulating contact segment is stacked and covers the insulating layer, and the first portion extends onto at least a part of the leakage contact segment.

[0016] In some embodiments, the isolation groove is located at a part of the conductive thin film layer corresponding to the leakage contact segment, so that the first portion covers a part of the leakage contact segment.

[0017] In some embodiments, the length of the part of the first portion extending onto the leakage contact segment in the first direction is greater than or equal to 10 μm.

[0018] In some embodiments, the ratio between the length of the part of the first portion extending onto the leakage contact segment in the first direction and the length of the leakage contact segment in the first direction is greater than 90%.

[0019] In some embodiments, the isolation groove is located at a part of the conductive thin film layer corresponding to the insulating contact segment, so that the first portion covers the entire leakage contact segment.

[0020] In some embodiments, the isolation groove is located at a portion of the conductive thin film layer corresponding to the non-stacked region.

[0021] In some embodiments, in the stacked region, the insulation contact regions are provided on both sides of the leakage contact region in the first direction, the insulation contact segments are provided on both sides of the leakage contact segment in the first direction, and the isolation groove is located at the insulation contact segment closest to the non-stacked region.

[0022] In some embodiments, in the first direction, the length of the leakage contact segment is 10 μm - 600 μm, and in the second direction, the length of the leakage contact segment is 10 μm - 5000 μm.

[0023] In some embodiments, in the first direction, the length of the leakage contact segment is 10 μm - 150 μm, and in the second direction, the length of the leakage contact segment is 20 μm - 500 μm.

[0024] In some embodiments, in a single extension portion, the area of the portion of the first part corresponding to the leakage contact segment is 100 μm 2 - 50000 μm 2 .

[0025] In some embodiments, in the back-contact battery, the ratio of the sum of the areas of all the portions of the first part corresponding to the leakage contact segment to the area of the back surface is 1.5×10 -8 - 1.5×10 -5 .

[0026] In some embodiments, in the second doping layer, the main body portion extends continuously in the second direction, and the extension portion is formed at a preset position of the main body portion.

[0027] In some embodiments, in the second direction, a plurality of extension portions are provided at one side of the main body portion at intervals.

[0028] In some embodiments, in the second direction, the distance between two adjacent extension portions located at one side of the main body portion is 1 cm - 10 cm.

[0029] In some embodiments, in the second direction, the distance between two adjacent extension portions located at one side of the main body portion is greater than or equal to 2 cm and less than 4 cm.

[0030] In some embodiments, the width of the isolation groove is greater than or equal to 10 μm.

[0031] In some embodiments, the insulating layer is a phosphosilicate glass layer, a borosilicate glass layer, or a borophosphosilicate glass layer; or

[0032] the insulating layer includes at least one of a silicon nitride film layer and an aluminum oxide film layer; or

[0033] The insulating layer has a double-layer film structure. The film layer structure of the insulating layer close to the silicon substrate includes at least one of an aluminum oxide film layer and a silicon oxide film layer, and the film layer structure facing away from the silicon substrate includes at least one of a silicon nitride film layer, a silicon oxynitride film layer, and a silicon oxide film layer.

[0034] In some embodiments, the silicon substrate further includes a plurality of side surfaces connecting the front surface and the back surface, and at least a part of the side surfaces are stacked with a third passivation layer, and a fourth passivation layer is provided on the front surface.

[0035] In some embodiments, a plurality of the side surfaces include a cutting surface, and the third passivation layer is stacked on the side surfaces except the cutting surface, and a fifth passivation layer is stacked on the cutting surface.

[0036] The present application further provides a battery assembly, and the battery assembly includes a plurality of the back contact batteries described in any one of the above.

[0037] The present application further provides a photovoltaic system, and the photovoltaic system includes the above-mentioned battery assembly.

[0038] In the back contact battery, battery assembly, and photovoltaic system according to the embodiments of the present application, the surface of the first doping layer facing away from the silicon substrate includes a stacked area and a non-stacked area, and the stacked area includes a leakage contact area and an insulating contact area. The insulating layer is stacked on the insulating contact area of the first doping layer. At least a part of the second doping layer includes a main body portion covering only the second pole region and an extending portion extending to cover the stacked area of the first doping layer, and the extending portion extends to cover the leakage contact area and covers at least a part of the leakage contact area. The conductive thin film layer is at least stacked and covered on the main body portion and the non-stacked area, and a plurality of isolation grooves are formed on the conductive thin film layer, and the isolation grooves extend along the second direction so that the conductive thin film layer includes a plurality of first parts and a plurality of second parts insulated from each other through the isolation grooves. The first part and / or the second part also extend to at least a part of the area corresponding to the leakage contact area of the extending portion. In this way, through the design of the extending portion on the second doping layer and the first part and the second part of the conductive thin film layer, the extending portion can form a leakage channel at the position corresponding to the leakage contact area of the first doping layer, so as to form a leakage point in the thickness direction, which can reduce the reverse breakdown voltage when the back contact battery is shaded, thereby improving the anti-thermal spot performance of the back contact battery and reducing the thermal spot risk of the battery assembly.

[0039] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Brief Description of the Drawings

[0040] Figure 1 is a schematic diagram of a module of a photovoltaic system provided by an embodiment of the present application;

[0041] Figure 2 is a schematic diagram of a module of a battery assembly provided by an embodiment of the present application;

[0042] Figure 3 is a schematic plan view of a back-contact battery provided by an embodiment of the present application;

[0043] Figure 4 is a schematic cross-sectional view of a back-contact battery provided by an embodiment of the present application;

[0044] Figure 5 is another schematic cross-sectional view of a back-contact battery provided by an embodiment of the present application;

[0045] Figure 6 is another schematic cross-sectional view of a back-contact battery provided by an embodiment of the present application;

[0046] Figure 7 is yet another schematic cross-sectional view of a back-contact battery provided by an embodiment of the present application.

[0047] Description of the Main Element Symbols:

[0048] Photovoltaic system 1000, battery assembly 200, back-contact battery 100, silicon substrate 10, front surface 11, back surface 12, first pole region 121, second pole region 122, first passivation layer 20, first doping layer 30, stacked region 31, leakage contact region 311, insulating contact region 312, non-stacked region 32, insulating layer 40, second passivation layer 50, second doping layer 60, body portion 61, extension portion 62, leakage contact segment 621, insulating contact segment 622, conductive thin film layer 70, isolation groove 701, first part 71, second part 72, first electrode 80, second electrode 90, third passivation layer 110, fourth passivation layer 120. Detailed Description of the Embodiments

[0049] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the following further describes the present application in detail with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0050] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0051] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined.

[0052] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection, an electrical connection or a connection that can communicate with each other; it may be directly connected or indirectly connected through an intermediate medium, and may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0053] In the present application, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0054] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0055] Please refer to Figure 1 - Figure 2 , the photovoltaic system 1000 in the embodiment of the present application may include the battery assembly 200 in the embodiment of the present application, and the battery assembly 200 in the embodiment of the present application may include a plurality of back-contact batteries 100 in the embodiment of the present application.

[0056] In the embodiment of the present application, a plurality of back-contact batteries 100 in the battery assembly 200 may be connected in series to form a plurality of battery strings, and each battery string may be connected in series, in parallel, or in a series-parallel combination to achieve the current confluence output. For example, the connection between each battery cell may be achieved by welding a welding tape, and the connection between each battery string may be achieved by a bus bar. In some embodiments, each battery string may form a battery cell array, and then be encapsulated together with a front plate, a front encapsulant film, a back encapsulant film, and a back plate to form the battery assembly 200.

[0057] Please refer to Figure 3 and Figure 4 , the back-contact battery 100 in the embodiment of the present application may include a silicon substrate 10, a first passivation layer 20, a first doping layer 30, an insulating layer 40, a second passivation layer 50, a second doping layer 60, and a conductive thin film layer 70.

[0058] The silicon substrate 10 has opposite front surface 11 and back surface 12. The back surface 12 includes a plurality of first pole regions 121 and a plurality of second pole regions 122. The plurality of first pole regions 121 and the plurality of second pole regions 122 are alternately arranged along a first direction, and both the first pole regions 121 and the second pole regions 122 extend along a second direction, and the second direction intersects with the first direction.

[0059] Specifically, as Figure 3 shown, the first pole regions 121 and the second pole regions 122 may be alternately arranged along the lateral direction of the silicon substrate 10 and both extend along the longitudinal direction. That is, the first direction may be the lateral direction of the back-contact battery 100, and the second direction may be the lateral direction of the back-contact battery 100, and the two are perpendicular to each other. Of course, in other embodiments, the first direction and the second direction may also be other directions. For example, the two may be the diagonal directions of the silicon substrate 10 respectively, and specific limitations are not made here.

[0060] The first passivation layer 20 and the first doping layer 30 are sequentially stacked on the first pole region 121. That is, along the thickness direction of the back-contact battery, the first passivation layer 20 and the first doping layer 30 are sequentially stacked on the first pole region 121. The first passivation layer 20 and the first doping layer 30 both completely cover the first pole region 121, and the first passivation layer 20 and the first doping layer 30 are provided on each first pole region 121. As Figure 4 shown, the surface of the first doping layer 30 facing away from the silicon substrate 10 has a stacked region 31 and a non-stacked region 32. The stacked region 31 includes a leakage contact region 311 and an insulating contact region 312.

[0061] The insulating layer 40 is stacked on the insulating contact region 312 of the first doping layer 30. The second passivation layer 50 and the second doping layer 60 are sequentially stacked on the second pole region 122. That is, along the thickness direction of the back-contact battery, the second passivation layer 50 and the second doping layer 60 are sequentially stacked on the second pole region 122. The second passivation layer 50 and the second doping layer 60 both completely cover the second pole region 122, and the second passivation layer 50 and the second doping layer 60 are provided on each second pole region 122. As Figure 4 shown, at least a part of the second doping layer 60 includes a main body portion 61 that only covers the second pole region 122 and an extension portion 62 that extends to the stacked region 31 of the first doping layer 30. That is, the extension portion 62 extends from the main body portion 61 to cover the stacked region 31 of the first doping layer 30. The extension portion 62 extends to the leakage contact region 311 and covers at least a part of the leakage contact region 311. Specifically, the extension portion 62 forms a leakage contact with the first doping layer 30 in the leakage contact region 311. That is, the extension portion 62 forms a leakage contact structure with the first doping layer 30 in the leakage contact region 311 along the thickness direction of the back-contact battery.

[0062] The conductive thin film layer 70 is at least stacked and covered on the main body portion 61 and the non-stacked region 32. Exemplarily, in some embodiments, the conductive thin film layer 70 may completely cover the entire back surface 12. As Figure 4 shown, a plurality of isolation grooves 701 are formed on the conductive thin film layer 70. The isolation grooves 701 extend along the second direction, so that the conductive thin film layer 70 includes a plurality of first parts 71 and a plurality of second parts 72 that are insulated and isolated by the isolation grooves 701. The first parts 71 and the second parts 72 are alternately arranged along the first direction. The first parts 71 are stacked and covered on the main body portion 61 and are electrically connected to the main body portion 61. The second parts 72 are stacked and covered on the non-stacked region 32 and are electrically connected to the first doping layer 30 in the non-stacked region 32.

[0063] That is to say, the isolation groove 701 extends through both sides of the conductive thin film layer 70 along the second direction. By forming a plurality of isolation grooves 701 in the conductive thin film layer 70, the conductive thin film layer 70 can be divided into a plurality of first parts 71 and a plurality of second parts 72 separated by the isolation grooves 701. The two sides of the isolation groove 701 are the first part 71 and the second part 72 respectively.

[0064] Wherein, the first part 71 and / or the second part 72 also extend to at least a partial area of the part of the extension part 62 corresponding to the leakage contact area 311. Thus, in the second doping layer 60 and the first doping layer 30, by the extended arrangement of the first part 71 and / or the second part 72, a leakage channel can be formed in the thickness direction between the part of the extension part 62 covering the leakage contact area 311 and the first doping layer 30.

[0065] It should be noted that in this text, when a certain film layer covers or is stacked and covers a partial area or the entire area of a certain surface or a certain film layer, it can be that the film layer is directly stacked on the surface or a certain film layer, or there are other film layers provided between the film layer and the surface or the film layer. The coverage only serves to define the specific setting range of the film layer.

[0066] In addition, it should also be noted that in this text, "leakage contact" means that there is no insulation between the extension part 62 and the leakage contact area 311 of the first doping layer 30, but leakage conduction forms a leakage point. The two can form a leakage point by direct contact, or can achieve the function of leakage contact through other dielectric layers for tunneling.

[0067] For example, as Figure 4 shown, in some embodiments, a second passivation layer 50 can also be provided between the extension part 62 and the leakage contact area 311. The extension part 62 is conducted with the first doping layer 30 through the passivation layer at the leakage contact area 311. In such a case, the first passivation layer 20 and the first doping layer 30 form a first passivation contact structure, the second passivation layer 50 and the second passivation layer 50 form a second passivation contact structure. The first passivation contact structure is stacked in the first pole region 121, and the second passivation contact structure is stacked in the second pole region 122 and extends to cover the stacking area 31 of the first doping layer 30 and at least cover a part of the leakage contact area 311.

[0068] In the back-contact battery 100, the battery assembly 200, and the photovoltaic system 1000 according to the embodiments of the present application, the surface of the first doping layer 30 facing away from the silicon substrate 10 includes a stacked region 31 and a non-stacked region 32. The stacked region 31 includes a leakage contact region 311 and an insulating contact region 312. The insulating layer 40 is stacked on the insulating contact region 312 of the first doping layer 30. At least a part of the second doping layer 60 includes a main body portion 61 that only covers the second pole region 122 and an extension portion 62 that extends and covers the stacked region 31 of the first doping layer 30. The extension portion 62 extends and covers the leakage contact region 311 and covers at least a part of the leakage contact region 311. The conductive thin film layer 70 is at least stacked and covered on the main body portion 61 and the non-stacked region 32. A plurality of isolation grooves 701 are formed on the conductive thin film layer 70. The isolation grooves 701 extend along the second direction so that the conductive thin film layer 70 includes a plurality of first portions 71 and a plurality of second portions 72 that are insulated and isolated by the isolation grooves 701. The first portion 71 and / or the second portion 72 also extend to at least a part of the region corresponding to the leakage contact region 311 of the extension portion 62. Thus, through the design of the extension portion 62 on the second doping layer 60 and the first portion 71 and the second portion 72 of the conductive thin film layer 70, the extension portion 62 can form a leakage channel at the position corresponding to the leakage contact region 311 of the first doping layer 30, so as to form a leakage point in the thickness direction, which can reduce the reverse breakdown voltage when the back-contact battery 100 is shaded, thereby improving the thermal hotspot resistance of the back-contact battery 100 and reducing the thermal hotspot risk of the battery assembly 200.

[0069] At the same time, through the design of the insulating layer 40, it is possible to prevent the extension length of the extension portion 62 in the first direction from being too long, resulting in an excessive leakage area and efficiency loss. At the same time, the setting of the insulating layer 40 can also further improve the passivation effect of the back-contact battery, balance the relationship between the thermal hotspot resistance and the efficiency, and enable the thermal hotspot resistance and the efficiency to achieve a better matching effect.

[0070] That is to say, in the present application, through the matching and optimization design of the first doping layer 30, the second doping layer 60, the conductive thin film layer 70, and the insulating layer 40, the thermal hotspot resistance and the efficiency of the back-contact battery can achieve a better matching effect, while ensuring the efficiency of the back-contact battery while improving the thermal hotspot resistance.

[0071] Specifically, in the embodiments of the present application, the silicon substrate 10 can be an N-type silicon substrate 10 or a P-type silicon substrate 10, and specific limitations are not made here. The first doping layer 30 can be an N-type doping layer, and the second doping layer 60 can be a P-type doping layer, or the first doping layer 30 is a P-type doping layer and the second doping layer 60 is an N-type doping layer. Specific limitations are not made here, as long as the polarities of the two are opposite.

[0072] The conductive thin film layer 70 can preferably be a transparent conductive thin film layer, such as a TCO thin film layer, which can improve the bifaciality of the back-contact battery while achieving current collection. In other embodiments, the conductive thin film layer 70 can also be a metal thin film layer, such as at least one of metal layers such as an aluminum layer, a nickel layer, and a copper layer. Of course, in some embodiments, the conductive thin film layer 70 can also be a bilayer structure composed of a transparent conductive film layer and a metal thin film layer, which is not specifically limited herein.

[0073] In the embodiments of the present application, the back-contact battery can be a hybrid back-contact battery. Specifically, in such a back-contact battery, the first doping layer 30 can be a doped polysilicon layer and the polarity of the first doping layer 30 is N-type, that is, the first doping layer 30 can be an N-type doped polysilicon layer, and the first passivation layer 20 is a tunneling oxide layer, such as a tunneling silicon oxide layer. The second passivation layer 50 can be at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer (such as a tunneling silicon oxide layer), and the first doping layer 30 is at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer. In this way, by designing the first doping layer 30 as a doped polysilicon layer and the second doping layer 60 as at least one of a doped amorphous silicon layer and a doped microcrystalline silicon, a hybrid back-contact battery can be formed to improve the efficiency of the back-contact battery.

[0074] In a preferred embodiment, the first passivation layer 20 is a tunneling oxide layer, the first doping layer 30 is an N-type doped polysilicon layer, the second passivation layer 50 is an intrinsic amorphous silicon layer, and the second doping layer 60 is a P-type doped amorphous silicon layer or a P-type doped microcrystalline silicon layer.

[0075] It can be understood that since the lateral conductivity of doped amorphous silicon and doped microcrystalline silicon is poor, a stacked structure in the thickness direction is formed at the leakage contact area 311 of the first doping layer 30 through the extension portion 62, so that the first doping layer 30 and the second doping layer 60 can form a leakage contact structure in the thickness direction, thereby improving the efficiency of the back-contact battery.

[0076] Furthermore, in the embodiments of the present application, the lateral conductivity of doped amorphous silicon and doped microcrystalline silicon is poor, and the first pole region 121 and the second pole region 122 may not be isolated by a trench, that is, the first doping layer 30 and the body portion 61 may not need to be isolated by a trench. The body portion 61 of the second doping layer 60 and the first doping layer 30 can be adjacent in the first direction, and the two do not need to be isolated by designing a trench or other insulating structures, which can increase the coverage area of the back surface 12 doping layer and further improve the efficiency of the back-contact battery.

[0077] Of course, it can be understood that in some embodiments, the first passivation layer 20 may also be at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer, the first doping layer 30 may be at least one of a doped amorphous silicon layer and doped microcrystalline silicon, the second passivation layer 50 may be a tunneling oxide layer, and the second doping layer 60 may be a doped polysilicon layer. The setting methods for the two cases are as follows:

[0078] The first case: As Figure 4 shown, when the first passivation layer 20 is a tunneling oxide layer, the first doping layer 30 is a doped polysilicon layer, the second passivation layer 50 is at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer, and the second doping layer 60 is at least one of a doped amorphous silicon layer and doped microcrystalline silicon, the first portion 71 extends to at least a partial area of the portion of the extension portion 62 corresponding to the leakage contact region 311, or both the first portion 71 and the second portion 72 extend to the portion of the extension portion 62 corresponding to the leakage contact region 311.

[0079] In such a case, on the extension portion 62 located in the leakage contact region 311, the area covered by the first portion 71 is the effective leakage area, and the area not covered by the first portion 71 is the ineffective leakage area. In a back-contact battery, only the effective leakage area can function to improve the anti-thermal-spot performance.

[0080] The second case: When the first passivation layer 20 is at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer, the first doping layer 30 is at least one of a doped amorphous silicon layer and doped microcrystalline silicon, the second passivation layer 50 is a tunneling oxide layer, and the second doping layer 60 is a doped polysilicon layer, it may be that the second portion 72 extends to at least a partial area of the portion of the extension portion 62 corresponding to the leakage contact region 311, or both the first portion 71 and the second portion 72 extend to the portion of the extension portion 62 corresponding to the leakage contact region 311.

[0081] In such a case, on the extension portion 62 located in the leakage contact region 311, the area covered by the second portion 72 is the effective leakage area, and the area not covered by the second portion 72 is the ineffective leakage area. In a back-contact battery, only the effective leakage area can function to improve the anti-thermal-spot performance.

[0082] In addition, as Figure 3 shown, in the embodiments of the present application, in a back-contact battery, all of the second doping layers 60 may have the extension portion 62, or only some of the second doping layers 60 may have the extension portion 62. Specifically, there is no limitation here, as long as the leakage contact area formed by the extension portion 62 and the first doping layer 30 does not cause a significant reduction in the efficiency of the back-contact battery.

[0083] As Figure 3As shown, for a single second doping layer 60, one or more extensions 62 can be formed on the body portion 61. When the number of extensions 62 is multiple, on the body portion 61, the extensions 62 can be arranged at intervals along the second direction.

[0084] In addition, in some embodiments, for a single second doping layer 60, extensions 62 can be formed only on one side, or extensions 62 can be formed on both sides. When extensions 62 are formed on both sides, both side extensions 62 can correspond to one leakage contact region 311, or only the extensions 62 on one side can correspond to the leakage contact region 62, and an insulating layer 40 is provided between the other extensions 62 and the first doping layer 20. There is no specific limitation here.

[0085] In some embodiments, the insulating layer 40 can be a film layer with insulating function, which can be obtained by locally etching and removing the mask layer laminated and covered on the first doping layer 30 during the production process.

[0086] In some embodiments, the insulating layer 40 can be a phosphosilicate glass film layer, a borosilicate glass film layer, or a borophosphosilicate glass film layer. These film layers can be film layers automatically formed on the first doping layer 30 during the manufacturing process.

[0087] Of course, in some embodiments, the insulating layer 40 can also be at least one of an alumina film layer or a silicon nitride film layer.

[0088] In addition, in some embodiments, the insulating layer 40 can also be at least one of a silicon oxide film layer or a silicon oxynitride film layer. There is no specific limitation here.

[0089] Further, in some embodiments, the insulating layer 40 can be a double-layer film structure. Among them, the film layer structure of the insulating layer 40 close to the silicon substrate 10 can include at least one of an alumina film layer or a silicon oxide film layer, and the film layer structure facing away from the silicon substrate 10 can include at least one of a silicon nitride film layer, a silicon oxynitride film layer, or a silicon oxide film layer. There is no specific limitation here.

[0090] Please refer to Figure 4 , in the back-contact battery of the present application, a first electrode 80 is provided on the first part 71, and a second electrode 90 is provided on the second part 72. In this way, the first electrode 80 and the second electrode 90 can be provided on the conductive thin film layer 70 to achieve the current converging output and the series connection between two battery chips.

[0091] Further, in such an embodiment, the first electrode 80 can be located in the non-stacking region 32, and the second electrode 90 can be located in the second pole region 122.

[0092] With such a setting, the resistance loss of the first electrode 80 and the second electrode 90 during the current collection process can be reduced, improving the conversion efficiency.

[0093] Please refer to Figure 4 , in some embodiments, the extension portion 62 may include a leakage contact section 621 and an insulating contact section 622. The leakage contact section 621 is stacked and covers the leakage contact area 311, and the insulating contact section 622 is stacked and covers the insulating layer 40. The first portion 71 extends to at least a partial area of the leakage contact section 621.

[0094] In this way, the leakage contact section 621 completely covers the leakage contact area 311 to form a leakage contact with the first doped layer 30, and the insulating contact section 622 covers the insulating layer 40 to be isolated from the first doped layer 30 through the insulating layer 40. Through the setting of the insulating layer 40, it is possible to avoid excessive leakage contact area and excessive efficiency loss caused by the extension portion 62 extending too long in the first direction during the manufacturing process. That is, through the setting of the insulating layer 40, the efficiency of the back-contact battery can be ensured while improving the anti-thermal spot performance.

[0095] Specifically, in such an embodiment, the first passivation layer 20 is a tunneling oxide layer, the first doped layer 30 is a doped polysilicon layer, the second passivation layer 50 is at least one of a tunneling oxide layer and an intrinsic amorphous silicon layer, and the second doped layer 60 is at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer. The insulating contact section 622 may completely cover the insulating layer 40 or only cover a partial area of the insulating layer 40, and specific details are not limited here.

[0096] It should be noted that when the first doped layer 30 is a doped polysilicon layer and the second doped layer 60 is a doped amorphous silicon layer or a doped microcrystalline silicon layer, on the leakage contact section 621, the area covered by the first portion 71 is the effective leakage area, and the area not covered by the first portion 71 is the ineffective leakage area. In such an embodiment, the projected area of the portion of the first portion 71 located on the leakage contact section 621 in the thickness direction of the back-contact battery is the effective leakage area.

[0097] Please refer to Figure 4 , in some embodiments, the isolation groove 701 is located at the portion of the conductive thin film layer 70 corresponding to the insulating contact section 622, so that the first portion 71 covers the entire leakage contact section 621.

[0098] In this way, by opening the isolation groove 701 on the insulating contact section 622, the first portion 71 can completely cover the entire leakage contact section 621, and the area size of the entire leakage contact section 621 is the effective leakage contact area between the extension portion 62 and the first doped layer 30.

[0099] It should be noted that the statement "the isolation groove 701 is located at the portion of the conductive thin film layer 70 corresponding to the insulating contact segment 622" means that the orthographic projection of the isolation groove in the thickness direction is completely located within the insulating contact area 312.

[0100] Of course, in some embodiments, the isolation groove 701 may also be located at the portion of the conductive thin film layer 70 corresponding to the non-stacking area 32. In such embodiments, it is also possible to make the extension portion 62 completely cover the entire leakage contact area 311, and the area size of the entire leakage contact area 311 is the leakage contact area between the extension portion 62 and the first doped layer 30.

[0101] Please refer to Figure 3 , in some embodiments, the length L1 of the leakage contact segment 621 in the first direction may be 10 μm - 600 μm, and the length L2 of the leakage contact segment 621 in the second direction may be 10 μm - 5000 μm.

[0102] In this way, by reasonably setting the lengths of the leakage contact segment 621 in each direction, the area of the leakage contact segment 621 can be controlled within a reasonable range, so as to control the effective leakage contact area of a single extension portion 62 within a reasonable range, avoiding the situation where the anti-thermal spot performance cannot reach the expected effect due to too small a leakage contact area, and also avoiding too large a leakage contact area resulting in excessive efficiency loss. That is to say, such a setting can balance the relationship between the anti-thermal spot performance and the efficiency, making it reach a better matching effect.

[0103] Specifically, in such embodiments, the length of the leakage contact segment 621 in the first direction may be, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm or any value between 10 μm - 600 μm. The length of the leakage contact segment 621 in the second direction may be, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm, 1000 μm, 1500 μm, 2000 μm, 2500 μm, 3000 μm, 3500 μm, 4000 μm, 4500 μm, 5000 μm or any value between 10 μm - 5000 μm.

[0104] Further, in such an embodiment, the length L1 of the leakage contact section 621 in the first direction is preferably 10 μm - 150 μm, and the length L2 of the leakage contact section 621 in the second direction is preferably 20 μm - 500 μm.

[0105] Of course, please refer to Figure 5 , in some embodiments, the isolation groove 701 may also be located at a portion of the conductive thin film layer 70 corresponding to the leakage contact section 621, so that the first portion 71 covers a part of the leakage contact section 621.

[0106] In this way, by opening the isolation groove 701 in the leakage contact section 621, the first portion 71 can only cover a part of the leakage contact section 621, thereby controlling the effective leakage contact area between the first doping layer 30 and the second doping layer 60.

[0107] It should be noted that "the isolation groove 701 is located at a portion of the conductive thin film layer 70 corresponding to the leakage contact section 621" means that the orthographic projection of the isolation groove in the thickness direction is located at the leakage contact section 621.

[0108] In Figure 5 the shown embodiment, the length of the portion where the first portion 71 extends to the leakage contact section 621 in the first direction is greater than or equal to 10 μm.

[0109] In this way, it is possible to avoid a poor effect on the thermal hotspot resistance performance due to too small an extension length of the first portion 71.

[0110] Further, in such an embodiment, the ratio between the length of the portion where the first portion 71 extends to the leakage contact section 621 in the first direction and the length of the leakage contact section 621 in the first direction is greater than 90%, such as 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc.

[0111] In this way, by setting the ratio of the length of the first portion 71 extending to the leakage contact section 621 to the length of the leakage contact section 621 within a relatively optimal range greater than 90%, it is possible to effectively improve the thermal hotspot resistance performance while ensuring the conversion efficiency.

[0112] Specifically, as described above, in some embodiments, the length of the leakage contact section 621 in the first direction is 10 μm - 600 μm, preferably 10 μm - 150 μm. Then, in this embodiment, the minimum value of the length of the portion where the first portion 71 extends to the leakage contact section 621 in the first direction is greater than 9 μm, and the maximum value can be greater than 540 μm and less than or equal to 600 μm, preferably greater than 135 μm and less than 150 μm.

[0113] Please refer to Figure 6, in some embodiments, in the stacking region 31, on both sides of the leakage contact region 311 in the first direction, there are insulating contact regions 312, and on both sides of the leakage contact segment 621 in the first direction, there are insulating contact segments 622. The isolation groove 701 is located at the insulating contact segment 622 closest to the non-stacking region 32.

[0114] In this way, with the area of the stacking region 31 remaining unchanged, by setting multiple insulating contact regions 312, the area of the leakage contact region 311 can be controlled within a reasonable range, avoiding excessive efficiency loss caused by an overly large area of the leakage contact region 311.

[0115] At the same time, by opening the isolation groove 701 at the insulating contact segment 622 closest to the non-stacking region 32, it can be ensured that the part of the first portion 71 located on the leakage contact segment and the part of the first portion 71 located on the second pole region 122 are a continuous structure, thus ensuring that the leakage contact segment can achieve effective leakage contact with the first doped layer 30.

[0116] Please refer to Figure 3 , in some embodiments, in the second doped layer 60, the main body portion 61 extends continuously along the second direction, and the extending portion 62 is formed at a preset position of the main body portion 61.

[0117] In this way, the second doped layer 60 only has the extending portion 62 at a preset position of the main body portion 61, which can avoid a significant decrease in efficiency caused by an overly large area of the extending portion 62 resulting in an overly large area of the effective leakage region.

[0118] Of course, it can be understood that in a possible embodiment, in the second doped layer 60, the extending portion 62 can also extend continuously along the second direction to both sides of the main body portion 61 in the second direction. In such a case, to control the area of the effective leakage region, the efficiency loss can be avoided by controlling the area of the first portion 71 covering the leakage contact segment 621.

[0119] Please refer to Figure 6 , in some embodiments, on a single second doped layer 60, the number of extending portions 62 can be multiple, and the multiple extending portions 62 are arranged at intervals in the second direction. That is, on one side of the main body portion 61 in the second direction, there are multiple extending portions 62 arranged at intervals.

[0120] In this way, by setting multiple isolated extending portions 62 on the second doped layer 60, the efficiency loss caused by an overly large leakage contact area on a single second doped layer 60 can be avoided.

[0121] It can be understood that in some embodiments, when the second doping layer 60 forms a leakage contact with both adjacent first doping layers 30, extension portions 62 are formed on both sides of the second doping layer 60 in the first direction; when the second doping layer 60 forms a leakage contact with only one first doping layer 30, an extension portion 62 is formed only on one side of the second doping layer 60 in the first direction.

[0122] Further, in some embodiments, in the second direction, the distance H1 between two adjacent extension portions 62 is 1 cm - 10 cm.

[0123] In this way, it is possible to avoid the distance H1 between two adjacent extension portions 62 being too small and the leakage points being too concentrated, resulting in the heat generated not being dissipated in time and causing a significant increase in temperature.

[0124] Specifically, in such an embodiment, the distance H1 between two adjacent extension portions 62 can be, for example, 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, 6 cm, 6.5 cm, 7 cm, 7.5 cm, 8 cm, 8.5 cm, 9 cm, 9.5 cm, 10 cm or any value between 1 cm and 10 cm.

[0125] Further, in such an embodiment, in the second direction, the distance H1 between two adjacent extension portions 62 is preferably greater than or equal to 2 cm and less than 4 cm.

[0126] In this way, through the research and demonstration of the inventors of the present application, setting the distance within this preferred range can, to the greatest extent, avoid excessive heat concentration when the number of extension portions 62 is set to be relatively large. That is to say, this can balance the anti - hot - spot performance and the relationship of excessive heat concentration to achieve an optimal matching effect.

[0127] Specifically, in such an embodiment, the distance H1 between two adjacent extension portions 62 can be preferably, for example, 2 cm, 2.2 cm, 2.4 cm, 2.6 cm, 2.8 cm, 3 cm, 3.1 cm, 3.2 cm, 3.3 cm, 3.4 cm, 3.5 cm, 3.6 cm, 3.7 cm, 3.9 cm, 3.95 cm.

[0128] In some embodiments, in the back - contact battery 100, the distribution density of the extension portions 62 is 0.01 piece / cm 2 -1.5 pieces / cm 2 . In this way, by reasonably controlling the distribution density of the extension portions 62, it is possible to avoid the leakage points being too concentrated.

[0129] In such an embodiment, the distribution density of the extension portion 62 refers to the ratio between the sum of the number of the extension portions 62 on the back contact battery 100 and the area of the back surface 12 of the back contact battery 100. Specifically, the distribution density of the extension portion 62 can be, for example, 0.01 pieces / cm 2 , 0.05 pieces / cm 2 , 0.1 pieces / cm 2 , 0.2 pieces / cm 2 , 0.3 pieces / cm 2 , 0.4 pieces / cm 2 , 0.5 pieces / cm 2 , 0.6 pieces / cm 2 , 0.7 pieces / cm 2 , 0.8 pieces / cm 2 , 0.9 pieces / cm 2 , 1 piece / cm 2 , 1.1 pieces / cm 2 , 1.2 pieces / cm 2 , 1.3 pieces / cm 2 , 1.4 pieces / cm 2 , 1.5 pieces / cm 2 or any value between 0.01 pieces / cm 2 and 1.5 pieces / cm 2 .

[0130] In some embodiments, in a single extension portion 62, the area of the portion of the single extension portion 62 where the first portion 71 corresponds to the leakage contact segment 621 is 100 μm 2 -50000 μm 2 .

[0131] Thus, by controlling the area of the portion of the first portion 71 corresponding to the leakage contact segment 621 within this reasonable range, the anti-thermal spot performance can be improved while ensuring that the efficiency loss is not too large.

[0132] Specifically, in such an embodiment, the area of the portion of a single first portion 71 corresponding to the leakage contact segment 621 can be, for example, 100 μm 2 , 200 μm 2 , 300 μm 2 , 350 μm 2 , 400 μm 2 , 450 μm 2 , 480 μm 2 , 500 μm 2 , 600 μm 2 , 700 μm 2 , 800 μm 2 , 900 μm 2 , 1000 μm2 、1100 μm 2 、1200 μm 2 、1300 μm 2 、1400 μm 2 、1500 μm 2 、2000 μm 2 、3000 μm 2 、4000 μm 2 、5000 μm 2 、6000 μm 2 、7000 μm 2 、8000 μm 2 、9000 μm 2 、10000 μm 2 、15000 μm 2 、20000 μm 2 、25000 μm 2 、30000 μm 2 、35000 μm 2 、40000 μm 2 、45000 μm 2 、50000 μm 2 or 100 μm 2 -50000 μm 2 any value between them.

[0133] In some embodiments, in the back contact battery, the sum of the areas of all the portions of the first part 71 corresponding to the leakage contact section 621 (i.e., the sum of the effective leakage areas on each extension portion 62 in the back contact battery) and the area of the back surface 12 is 1.5×10 -8 -1.5×10 -5 .

[0134] Thus, setting the ratio of the sum of the areas of all the portions of the first part 71 corresponding to the leakage contact section 621 to the area of the back surface 12 within this reasonable range can avoid the situation where the area ratio of the leakage contact is too large and seriously affects the efficiency of the back contact battery 100. That is to say, it can ensure the efficiency of the back contact battery 100 while ensuring the anti-thermal spot performance.

[0135] Specifically, in such an embodiment, the area ratio between the two can be, for example, 1.5×10 -8 , 2×10 -8 , 2.5×10 -8 , 3.5×10 -8 , 4.5×10 -8 , 4.5×10 -8 , 5×10 -8 , 6×10 -8 , 7×10-8 、 8 * 10 -8 、 9 * 10 -8 、 1 * 10 -7 、 1 * 10 -6 、 1 * 10 -5 、 1.5 * 10 -5 Or 4.5 * 10 -8 -1.5 * 10 -5 Any other value between them is not specifically limited here. In some embodiments, the ratio between the two may preferably be greater than 1.5 * 10 -8 and less than 4.5 * 10 -8 .

[0136] In some embodiments, the width of the isolation groove 701 (i.e., the length of the isolation groove 701 in the first direction) is greater than or equal to 10 μm. In this way, efficient insulation isolation between the first part 71 and the second part 72 can be achieved.

[0137] Please refer to Figure 7 , in some embodiments, the silicon substrate 10 further includes a plurality of side surfaces connecting the front surface 11 and the back surface 12, and at least part of the side surfaces are laminated with a third passivation layer 110, and a fourth passivation layer 120 is provided on the front surface 11.

[0138] In this way, the front surface 11 and the side surfaces can be efficiently passivated through the third passivation layer 110 and the fourth passivation layer 120, and while protecting the side surfaces, the passivation effect of the back-contact battery can be improved.

[0139] Specifically, in such an embodiment, the third passivation layer 110 may also be at least one of an alumina film layer or a silicon nitride film layer. In addition, in some embodiments, the third passivation layer 110 may also be at least one of a silicon oxide film layer or a silicon oxynitride film layer, which is not specifically limited here. Of course, in some embodiments, the third passivation layer 110 may also be a bilayer film structure. Among them, the film layer structure of the third passivation layer 110 close to the silicon substrate 10 may include at least one of an alumina film layer or a silicon oxide film layer, and the film layer structure facing away from the silicon substrate 10 may include at least one of a silicon nitride film layer, a silicon oxynitride film layer or a silicon oxide film layer, which is not specifically limited here.

[0140] The fourth passivation layer 120 may also be at least one of an aluminum oxide film layer or a silicon nitride film layer. In addition, in some embodiments, the fourth passivation layer 120 may also be at least one of a silicon oxide film layer or a silicon oxynitride film layer, and specific details are not limited herein. Of course, in some embodiments, the fourth passivation layer 120 may also be a bilayer film structure. Among them, the film layer structure of the fourth passivation layer 120 close to the silicon substrate 10 may include at least one of an aluminum oxide film layer or a silicon oxide film layer, and the film layer structure facing away from the silicon substrate 10 may include at least one of a silicon nitride film layer, a silicon oxynitride film layer, or a silicon oxide film layer, and specific details are not limited herein.

[0141] It can be understood that, in some embodiments, the back-contact battery may be a full-chip battery that has not been sliced. In such a case, the third passivation layer 110 is stacked on all sides of the back-contact battery.

[0142] In some embodiments, the back-contact battery may also be a sliced battery obtained through a slicing process. In such a case, several sides of the back-contact battery include a cutting surface, and the third passivation layer 110 is stacked on the sides other than the cutting surface, and a fifth passivation layer is stacked on the cutting surface. The fifth passivation layer may be at least one of a silicon nitride film layer, a silicon oxide film layer, and a silicon oxynitride film layer.

[0143] In the description of this specification, the descriptions with reference to terms such as "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0144] In addition, the above are only the preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back-contact battery, characterized in that, Comprising: A silicon substrate having opposite front and back surfaces, the back surface including a plurality of first pole regions and a plurality of second pole regions arranged alternately in a first direction, the first pole regions and the second pole regions both extending in a second direction, the second direction intersecting the first direction; A first passivation layer and a first doped layer stacked in sequence on the first pole region, the surface of the first doped layer facing away from the silicon substrate having a stacked region and a non-stacked region, the stacked region including a leakage contact region and an insulating contact region; An insulating layer stacked on the insulating contact region; A second passivation layer and a second doped layer stacked in sequence on the second pole region, at least a part of the second doped layer including a body portion covering only the second pole region and an extension portion extending onto the stacked region, the extension portion extending onto the leakage contact region and covering at least a part of the leakage contact region; And A conductive thin film layer covering at least the body portion and the non-stacked region, a plurality of isolation grooves being formed in the conductive thin film layer, the isolation grooves extending in the second direction, so that the conductive thin film layer includes a plurality of first parts and a plurality of second parts insulated from each other by the isolation grooves, the first parts being stacked and covering the body portion, and the second parts being stacked and covering the non-stacked region; The first part and / or the second part further extends onto at least a part of the region of the extension portion corresponding to the leakage contact region.

2. The back-contact battery according to claim 1, characterized in that, The first passivation layer is a tunneling oxide layer, and the first doped layer is a doped polysilicon layer; The second passivation layer is at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer, and the second doped layer is at least one of a doped amorphous silicon layer and doped microcrystalline silicon.

3. The back-contact battery according to claim 1, wherein, The extension portion includes a leakage contact segment and an insulating contact segment, the leakage contact segment being stacked and covering the leakage contact region, the insulating contact segment being stacked and covering the insulating layer, and the first part extending onto at least a part of the leakage contact segment.

4. The back contact battery according to claim 3, wherein The isolation groove is located at the part of the conductive thin film layer corresponding to the leakage contact segment, so that the first part covers a part of the leakage contact segment.

5. The back-contact battery according to claim 4, characterized in that, The length of the part of the first part extending onto the leakage contact segment in the first direction is greater than or equal to 10 μm.

6. The back-contact battery according to claim 4, characterized in that, The ratio between the length of the part of the first part extending onto the leakage contact segment in the first direction and the length of the leakage contact segment in the first direction is greater than 90%.

7. The back-contact battery according to claim 3, characterized in that, The isolation groove is located at the part of the conductive thin film layer corresponding to the insulating contact segment, so that the first part covers the entire leakage contact segment.

8. The back-contact battery according to claim 3, characterized in that, The isolation groove is located at the part of the conductive thin film layer corresponding to the non-stacked region.

9. The back contact battery according to claim 3, characterized in that, In the stacked region, the insulating contact regions are both on two sides of the leakage contact region in the first direction, the insulating contact segments are both on two sides of the leakage contact segment in the first direction, and the isolation groove is located at the insulating contact segment closest to the non-stacked region.

10. The back contact battery according to any one of claims 3-9, characterized in that, In the first direction, the length of the leakage contact section is 10 μm - 600 μm, and in the second direction, the length of the leakage contact section is 10 μm - 5000 μm.

11. The back-contact battery according to claim 10, wherein, In the first direction, the length of the leakage contact section is 10 μm - 150 μm, and in the second direction, the length of the leakage contact section is 20 μm - 500 μm.

12. The back-contact battery according to claim 3, characterized in that, In a single said extension part, the area of the part of the first part corresponding to the leakage contact section is 100 μm 2 - 50000 μm 2 .

13. The back-contact battery according to claim 3, characterized in that, In the back-contact battery, the ratio of the sum of the areas of all the portions of the first part corresponding to the portion of the leakage contact section to the area of the back surface is 1.5×10 -8 -1.5×10 -5 .

14. The back contact battery according to claim 1, wherein In the second doped layer, the body portion extends continuously in the second direction, and the extension portion is formed at a preset position of the body portion.

15. The back-contact battery according to claim 14, wherein, In the second direction, one side of the body portion has a plurality of extension portions arranged at intervals.

16. The back contact battery according to claim 14, characterized in that, In the second direction, the distance between two adjacent extension portions on one side of the body portion is 1 cm - 10 cm.

17. The back contact battery according to claim 14, wherein, In the second direction, the distance between two adjacent extension portions on one side of the body portion is greater than or equal to 2 cm and less than 4 cm.

18. The back contact battery according to claim 1, characterized in that, The width of the isolation groove is greater than or equal to 10 μm.

19. The back contact battery according to claim 1, characterized in that, The insulating layer is a phosphosilicate glass layer or a borosilicate glass layer or a borophosphosilicate glass layer; or The insulating layer includes at least one of a silicon nitride film layer and an aluminum oxide film layer; or The insulating layer has a double-layer film structure. The film layer structure of the insulating layer close to the silicon substrate includes at least one of an aluminum oxide film layer and a silicon oxide film layer, and the film layer structure facing away from the silicon substrate includes at least one of a silicon nitride film layer, a silicon oxynitride film layer, and a silicon oxide film layer.

20. The back-contact battery according to claim 1, wherein The silicon substrate further includes a plurality of side surfaces connecting the front surface and the back surface. At least part of the side surfaces are laminated with a third passivation layer, and the front surface is provided with a fourth passivation layer.

21. The back-contact battery according to claim 20, characterized in that, A plurality of the side surfaces include a cutting surface. The side surfaces other than the cutting surface are laminated with the third passivation layer, and the cutting surface is laminated with a fifth passivation layer.

22. A battery assembly, characterized in that, Including the back contact battery according to any one of claims 1 - 21.

23. A photovoltaic system, characterized in that, Including the battery assembly according to claim 22.

Images