Back contact battery, battery string, battery assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact cell, a cell string, a cell assembly and a photovoltaic system.The back contact cell comprises a silicon substrate, a first doping layer, a first insulating layer, a second doping layer and a conductive contact structure, and a first groove and a protruding part which are arranged in the first direction are formed on the back face of the back contact cell; the first doped layer is arranged on the convex part in a stacked mode, the second doped layer is arranged in the first groove in a stacked mode, the second doped layer comprises a first sub-doped layer and a second sub-doped layer which are arranged in a stacked mode, the polarity of the second doped layer is opposite to that of the first doped layer, and the conductive contact structure comprises an extending part. The thickness of the extending part in the thickness direction is larger than that of the convex part, the first doping layer and the first insulating layer. Therefore, the conductive contact structure can be used as a heat dissipation point, and the influence of hot spots is reduced or even eliminated. In addition, the first doping sub-layer and the second doping sub-layer are connected with the extending part, so that the contact area is increased, the conductive efficiency is improved, a plurality of electric leakage points are formed, and the safety is further improved.

Description

Technical Field

[0001] The present application belongs to the technical field of solar cells, and in particular relates to a back-contact cell, a cell string, a cell assembly and a photovoltaic system. Background Art

[0002] Solar energy is a sustainable source of clean energy. Solar cells use the photovoltaic effect of semiconductor pn junctions to convert solar energy into electrical energy. At present, back-contact solar cells are cells that place both the emitter and base contact electrodes on the back of the cell (non-light-receiving side). Back-contact cells have two doping layers of opposite conductivity types on the back of the cell, separated by a groove or an insulating layer. The safety performance of photovoltaic modules equipped with existing back-contact cells needs to be improved. Utility Model Content

[0003] The present application provides a back-contact cell, a cell string, a cell assembly and a photovoltaic system, which are intended to solve the problem of hot spots occurring during the use of photovoltaic cells.

[0004] The back contact battery provided in the present application includes a silicon substrate, a first doping layer, a first insulating layer, a second doping layer and a conductive contact structure, wherein the silicon substrate has a front side and a back side opposite to each other, a first groove and a convex portion arranged along a first direction are formed on the back side, the first doping layer is stacked on the convex portion, the first insulating layer is stacked on the first doping layer, the second doping layer is stacked in the first groove, the second doping layer includes a first sub-doping layer and a second sub-doping layer stacked, the first sub-doping layer is stacked on the first groove, the second sub-doping layer is stacked on a side of the first sub-doping layer away from the silicon substrate, the second doping layer has an opposite polarity to the first doping layer, the conductive type of the conductive contact structure is opposite to the conductive type of the first doping layer, the conductive contact structure includes an extension portion, the extension portion extends along the thickness direction of the silicon substrate, the extension portion is at least partially arranged in the first groove, only a partial area of ​​the first doping layer and only a partial area of ​​the second doping layer are respectively at least electrically connected to the extension portion, and the thickness of the extension portion in the thickness direction is greater than the total thickness of the convex portion, the first doping layer and the first insulating layer.

[0005] Furthermore, the conductive contact structure further includes a covering portion, wherein the covering portion is stacked on the first insulating layer, and an end of the protruding portion away from the first groove is connected to the covering portion.

[0006] Furthermore, the conductive contact structure and the second doped layer have the same conductivity type and are integrally continuous.

[0007] Furthermore, the back contact cell further comprises a first dielectric layer, a second dielectric layer and a third dielectric layer, wherein the first dielectric layer is located between the first doped layer and the silicon substrate;

[0008] The third dielectric layer is located between the second doped layer and the silicon substrate;

[0009] The second dielectric layer is at least partially disposed in the first trench and adheres to the sidewall of the protrusion.

[0010] Furthermore, the second dielectric layer extends in a thickness direction away from the silicon substrate, and the second dielectric layer is at least partially electrically connected to the first doped layer.

[0011] Furthermore, the back contact battery also includes an insulating dielectric layer, which is connected to an end of the second dielectric layer away from the silicon substrate, and a side of the insulating dielectric layer close to the protrusion is at least partially connected to the first doping layer and the first insulating layer.

[0012] Furthermore, the width of the insulating dielectric layer in the first direction is greater than the width of the second dielectric layer.

[0013] Furthermore, the extension portion further includes a first side and a second side arranged along the thickness direction, the first side is a side close to the convex portion, the first side contacts the second dielectric layer, and the second side is a side close to the first groove.

[0014] Furthermore, the back contact battery also includes a second insulating layer, the second insulating layer includes a first insulating part, a second insulating part and a third insulating part connected together in sequence, the first insulating part is stacked on the covering part, the second insulating part is arranged on the side of the second side close to the first groove, and the third insulating part is stacked on the second doping layer.

[0015] Furthermore, the first doping layer further includes a protruding portion extending above the first trench along the first direction, and the second dielectric layer surrounds the protruding portion.

[0016] Furthermore, the thickness of the first sub-doped layer in the thickness direction is greater than the thickness of the second sub-doped layer.

[0017] Furthermore, the thickness of the first sub-doped layer in the thickness direction is 50nm-300nm;

[0018] The thickness of the second sub-doping layer in the thickness direction is 30nm-200nm.

[0019] Furthermore, the first doping layer further includes a first inner expansion layer formed in the protrusion, and the second doping layer further includes a second inner expansion layer formed in the first groove.

[0020] Furthermore, the second doping layer further includes a barrier layer, and the barrier layer is stacked between the first sub-doping layer and the second sub-doping layer.

[0021] The battery string provided in the embodiments of the present application includes a back-contact battery as described in any of the embodiments above.

[0022] The battery assembly provided in the embodiments of the present application includes the battery string as described in the above embodiments.

[0023] The photovoltaic system provided in the embodiments of the present application includes the battery assembly as described in the above embodiments.

[0024] In the back-contact cell, cell string, cell assembly and photovoltaic system of the embodiments of the present application, the back-contact cell includes a silicon substrate, a first doping layer, a first insulating layer, a second doping layer and a conductive contact structure, the silicon substrate has a front side and a back side opposite to each other, a first groove and a convex portion arranged along a first direction are formed on the back side, the first doping layer is stacked on the convex portion, the first insulating layer is stacked on the first doping layer, the second doping layer is stacked in the first groove, the second doping layer includes a first sub-doping layer and a second sub-doping layer stacked, the first sub-doping layer is stacked on the first groove, the second sub-doping layer is stacked on the side of the first sub-doping layer away from the silicon substrate, the second doping layer has opposite polarity to the first doping layer, the conductive type of the conductive contact structure is opposite to the conductive type of the first doping layer, the conductive contact structure includes an extension portion, the extension portion extends along the thickness direction of the silicon substrate, the extension portion is at least partially arranged in the first groove, only a portion of the first doping layer and only a portion of the second doping layer are respectively electrically connected to at least the extension portion, and the thickness of the extension portion in the thickness direction is greater than the total thickness of the convex portion, the first doping layer and the first insulating layer. In this way, electrical energy can be released between the first doped layer and the second doped layer through the conductive contact structure, and the conductive contact structure can serve as a heat dissipation point to reduce or even eliminate the impact of hot spots and improve the power generation efficiency and safety of the back contact battery. At the same time, the first sub-doped layer and the second sub-doped layer are both connected to the extension to increase the contact area and increase the conductive efficiency. In addition, the conductive contact structure can be of the same conductive type as the second doped layer and be continuous as a whole, which simplifies the manufacturing process of the back contact battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic cross-sectional structure diagram of a back contact battery according to an embodiment of the present application;

[0026] Figure 2is another cross-sectional structural schematic diagram of a back contact battery according to an embodiment of the present application;

[0027] Figure 3 is another schematic cross-sectional structure diagram of a back contact battery according to an embodiment of the present application;

[0028] Figure 4 is another cross-sectional structural schematic diagram of a back contact battery according to an embodiment of the present application;

[0029] Figure 5 is a schematic diagram of the planar structure of a back contact battery according to an embodiment of the present application;

[0030] Figure 6 is a schematic structural diagram of a battery assembly according to an embodiment of the present application;

[0031] Figure 7 It is a structural schematic diagram of a photovoltaic system according to an embodiment of the present application.

[0032] Description of main component symbols:

[0033] Back contact cell 100, silicon substrate 10, front side 11, back side 12, first groove 121, convex portion 122, second groove 123, first doped layer 20, first inner expansion layer 21, protruding portion 25, retracted region 26, second doped layer 30, second inner expansion layer 31, first sub-doped layer 32, second sub-doped layer 33, barrier layer 34, first insulating layer 40, conductive contact structure 50, extension portion 51, first side 511, second side 512, covering portion 52, insulating dielectric layer 60, second insulating layer 70, first insulating portion 71, second insulating portion 72, third insulating portion 73, first dielectric layer 81, second dielectric layer 82, third dielectric layer 83, main grid 91, sub-grid 92, fine grid 93, cell string 200, cell assembly 300, photovoltaic system 400. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting 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 intended to limit the present application.

[0035] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are 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 understood as a limitation on the present application.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0039] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, 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.

[0040] In the related art, a back-contact battery has two doping layers of opposite conductivity types on the back of the battery. The two doping layers of opposite conductivity types are completely isolated from each other, which will make the back-contact battery have a higher reverse breakdown voltage, and further cause the photovoltaic modules including the existing back-contact battery to have a higher risk of hot spots during actual operation. The preparation of the conductor will increase the production cost and process of the back-contact battery, and the conductivity efficiency of the conductor is often poor. In the present application, the conductive contact structure can be used as a heat dissipation point to reduce or even eliminate the impact of hot spots and improve the power generation efficiency and safety of the back-contact battery. At the same time, the thickness of the extension portion along the thickness direction is relatively large, so that the extension portion can be electrically connected to the first sub-doping layer and the second sub-doping layer to form multiple leakage points, further improving safety. In addition, the conductive contact structure can be of the same conductivity type as the second doping layer and be continuous as a whole, which simplifies the production process of the back-contact battery.

[0041] Embodiment 1

[0042] See also Figure 1 , Figure 2 and Figure 3The back contact battery 100 provided in the present application includes a silicon substrate 10, a first doping layer 20, a first insulating layer 40, a second doping layer 30 and a conductive contact structure 50. The silicon substrate 10 has a front side 11 and a back side 12 opposite to each other. A first groove 121 and a convex portion 122 arranged along a first direction are formed on the back side 12. The first doping layer 20 is stacked on the convex portion 122. The first insulating layer 40 is stacked on the first doping layer 20. The second doping layer 30 is stacked in the first groove 121. The second doping layer 30 includes a first sub-doping layer 32 and a second sub-doping layer 33 stacked. The first sub-doping layer 32 is stacked on the second groove 123. The second sub-doping layer 33 is stacked on a side of the first sub-doping layer 32 away from the silicon substrate 10. The second doping layer 30 has opposite polarity to the first doping layer 20. The conductive contact structure 50 has a conductive type opposite to that of the first doping layer 20. The conductive contact structure 50 includes an extension portion 51. The extension portion 51 extends along the thickness direction of the silicon substrate 10. The extension portion 51 is at least partially arranged in the first groove 121. Only a partial area of ​​the first doping layer 20 and only a partial area of ​​the second doping layer 30 are respectively electrically connected to at least the extension portion 51. The thickness of the extension portion 51 in the thickness direction is greater than the total thickness of the protrusion 122, the first doping layer 20 and the first insulating layer 40.

[0043] In this embodiment, the front side 11 of the silicon substrate 10 is used to receive light, and the back side 12 of the silicon substrate 10 is formed with a first doping layer 20 and a second doping layer 30. On the back side 12 of the silicon substrate 10, the first groove 121 and the convex portion 122 are arranged along the first direction, and the first doping layer 20 and the second doping layer 30 respectively arranged in the convex portion 122 and the first groove 121 are also arranged along the first direction to form a photocurrent.

[0044] In addition, in the present embodiment, a conductive contact structure 50 is further formed between the first doping layer 20 and the second doping layer 30, and the conductive type of the conductive contact structure 50 is opposite to that of the first doping layer 20 and is the same as that of the second doping layer 30. The extension 51 of the conductive contact structure 50 can extend from the first groove 121, and the portion of the extension 51 located in the first groove 121 can be electrically connected to the second doping layer 30, while the extension 51 extends upward along the thickness direction, and the thickness of the extension 51 in the thickness direction is greater than the total thickness of the convex portion 122, the first doping layer 20 and the first insulating layer 40. In this way, the extension 51 can penetrate into the first groove 121 and electrically contact the first sub-doping layer 32 and the second sub-doping layer 33 respectively, thereby increasing the contact area between the extension 51 and the second doping layer 30. That is to say, the extension portion 51 can form a local leakage point with the contact position of the first sub-doping layer 32 and the second sub-doping layer 33 respectively, so as to electrically connect the first doping layer 20 and the second doping layer 30 to form a built-in diode with a lower reverse breakdown voltage, thereby making the back contact battery 100 have a lower reverse breakdown voltage when being blocked, eliminating the influence of hot spots.

[0045] Further, only a part of the first doping layer 20 and only a part of the second doping layer 30 are electrically connected to at least the extension 51, that is, the extension 51 can be electrically in contact with part of the first doping layer 20 and the second doping layer 30, respectively. The other areas of the first doping layer 20 and the second doping layer 30 can be physically isolated by the design of the first groove 121 and the convex portion 122, so as to avoid the first doping layer 20 and the second doping layer 30 being in full contact through the conductive contact structure 50, so that the leakage current of the back contact battery 100 is large when it is in normal working condition, resulting in low working efficiency of the back contact battery 100. In addition, the first sub-doping layer 32 and the second sub-doping layer 33 can also serve as mutual insurance. When one of the first sub-doping layer 32 or the second sub-doping layer 33 is damaged or short-circuited, the other sub-doping layer can also form a leakage point through the extension 51, thereby further improving safety.

[0046] In one embodiment, the first grooves 121 and the convex portions 122 are alternately arranged along the first direction, and the first grooves 121 and the convex portions 122 extend along the second direction, that is, the first doping layer 20 and the second doping layer 30 are also strips alternately arranged along the first direction and extend along the second direction. The second direction is perpendicular to the first direction and is located in the horizontal direction, that is, the plane formed by the first direction and the second direction is perpendicular to the thickness direction of the silicon substrate 10.

[0047] Please combine Figure 3In this embodiment, a second groove 123 extending along the second direction may be formed on the back side 12, and the second groove 123 is arranged between the first groove 121 and the convex portion 122 to physically isolate the first doped layer 20 and the second doped layer 30. In this embodiment, the second groove 123 can be arranged at a position between any adjacent first grooves 121 and convex portions 122, and the specific position is not limited here. In one example, the silicon substrate 10 can be further excavated on the basis of the first groove 121 to form a deeper second groove 123. In another example, the silicon substrate 10 can be further excavated on the basis of the convex portion 122 to form a second groove 123 deeper than the first groove 121. The specific groove setting position and distribution pattern are not limited here to meet various needs.

[0048] Please combine Figure 2 and Figure 3 In the present application, the first doping layer 20 and the second doping layer 30 may be a P-type doping layer and an N-type doping layer, respectively, as long as the polarities of the two are opposite. For example, in some embodiments, the first doping layer 20 may be a P-type polysilicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, which is not specifically limited here. Similarly, the second doping layer 30 may be an N-type polysilicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, which is not specifically limited here. When the first doping layer 20 is a P-type doping layer and the second doping layer 30 is an N-type doping layer, a P-type main gate 91 may be provided in the convex portion 122, and an N-type sub-gate 92 may be provided in the first groove 121. Of course, in other embodiments, a P-type fine gate 93 may be provided in the convex portion 122, and an N-type sub-gate 92 may be provided in the first groove 121, which is not specifically limited here.

[0049] Of course, in other embodiments, the first doping layer 20 and the second doping layer 30 may also be an N-type doping layer and a P-type doping layer, respectively, which is not specifically limited herein.

[0050] In the embodiment of the present application, the width of the convex portion 122 and the first groove 121 in the first direction and the ratio of the convex portion 122 and the first groove 121 are not limited, and the requirements can be met. In addition, in the embodiment of the present application, the height ratio between the convex portion 122 and the first groove 121 is not limited either, so as to meet different requirements.

[0051] Embodiment 2

[0052] See also Figure 1 and Figure 2 In some optional embodiments, the conductive contact structure 50 further includes a covering portion 52 , which is stacked on the first insulating layer 40 , and one end of the extension portion 51 away from the first groove 121 is connected to the covering portion 52 .

[0053] In this way, the protruding portion 51 and the covering portion 52 can be integrally formed, thereby simplifying the difficulty of preparing the conductive contact structure 50. At the same time, the covering portion 52 can cooperate with the protruding portion 51 to wrap and cover one side of the first doping layer 20 and the first insulating layer 40, thereby preventing the protruding portion 51 from extending insufficiently, resulting in the inability to form a leakage point between the protruding portion 51 and the first doping layer 20, thereby improving the manufacturing efficiency of the back contact battery 100.

[0054] Specifically, the extension portion 51 and the covering portion 52 of the conductive contact structure 50 may be an integrated structure to reduce etching accuracy and etching difficulty. At the same time, it can also ensure that the extension portion 51 corresponding to the first doping layer 20 can cover the side of the first doping layer 20 to form a local electrical connection state.

[0055] Embodiment 3

[0056] See also Figure 1 and Figure 2 In some optional embodiments, the conductive contact structure 50 and the second doped layer 30 have the same conductivity type and are integrally continuous.

[0057] In this way, the conductive contact structure 50 as a whole has the same conductive type as the second doped layer 30 and is continuous as a whole. That is to say, the conductive contact structure 50 and the second doped layer 30 can essentially be the same material layer. In this way, the conductive contact structure 50 and the second doped layer 30 can be manufactured simultaneously based on the same process to reduce the manufacturing difficulty of the conductive contact structure 50, simplify the manufacturing process of the conductive contact structure 50, and improve the manufacturing efficiency of the back contact battery 100.

[0058] Specifically, when the conductive contact structure 50 and the second doped layer 30 have the same conductive type and are continuous as one, the preparation process is greatly simplified. In this case, the conductive contact structure 50 can also form the same two-layer structure as the second doped layer 30, that is, in the process of preparing the first sub-doped layer 32 and the second sub-doped layer 33, the extension portion 51 and the covering portion 52 will also be a two-layer structure, and both of the two-layer structures can achieve the original functions.

[0059] In addition, in the present application, the first doping layer 20 may be a P-type doping layer, and the second doping layer 30 may be an N-type doping layer, that is, the protruding portion 51 and the covering portion 52 of the conductive contact structure 50 may also be N-type doping layers.

[0060] Embodiment 4

[0061] See also Figure 1 and Figure 2 In some optional embodiments, the back contact cell 100 further includes a first dielectric layer 81, a second dielectric layer 82 and a third dielectric layer 83, wherein the first dielectric layer 81 is located between the first doping layer 20 and the silicon substrate 10;

[0062] The third dielectric layer 83 is located between the second doped layer 30 and the silicon substrate 10;

[0063] The second dielectric layer 82 is at least partially disposed in the first trench 121 and adheres to the sidewall of the protrusion 122 .

[0064] In this embodiment, the first dielectric layer 81, the second dielectric layer 82 and the third dielectric layer 83 can be tunneling oxide layers, which play a role of tunneling effect, allowing carriers to be transmitted through the thin tunneling oxide layer, while providing a good surface passivation effect, reducing the recombination rate, thereby improving the efficiency of the back contact battery 100.

[0065] In the embodiment of the present application, the specific materials of the first dielectric layer 81, the second dielectric layer 82 and the third dielectric layer 83 are not limited to meet different requirements. At the same time, the materials of the first dielectric layer 81, the second dielectric layer 82 and the third dielectric layer 83 can be the same or different. Figure 1 The first dielectric layer 81, the second dielectric layer 82 and the third dielectric layer 83 are made of the same material; Figure 2 , the materials of the first dielectric layer 81, the second dielectric layer 82 and the third dielectric layer 83 are different. When the materials of the first dielectric layer 81, the second dielectric layer 82 and the third dielectric layer 83 are different, the first dielectric layer 81, the second dielectric layer 82 and the third dielectric layer 83 are discontinuous structures.

[0066] Embodiment 5

[0067] See also Figure 1 and Figure 2 In some optional embodiments, the second dielectric layer 82 extends in a thickness direction away from the silicon substrate 10 , and the second dielectric layer 82 is at least partially electrically connected to the first doped layer 20 .

[0068] In this way, both the second dielectric layer 82 and the extension portion 51 may be partially disposed in the first trench 121 and extend along the thickness direction of the silicon substrate 10 , that is, the extension portion 51 may be electrically connected to the first doping layer 20 through the second dielectric layer 82 .

[0069] Specifically, the second dielectric layer 82 may cover the first doping layer 20 on the side surface, so that the contact surfaces between the extension portion 51 and the second dielectric layer 82 are both effective electrical contact surfaces.

[0070] Embodiment 6

[0071] See also Figure 1 and Figure 2In some optional embodiments, the back contact battery 100 further includes an insulating dielectric layer 60 , which is connected to an end of the second dielectric layer 82 away from the silicon substrate 10 , and a side of the insulating dielectric layer 60 close to the protrusion 122 is at least partially connected to the first doping layer 20 and the first insulating layer 40 .

[0072] In this embodiment, the insulating dielectric layer 60 and the second dielectric layer 82 are flush on the side close to the extension 51, so that the side morphology of the extension 51 close to the protrusion 122 is smooth and regular, which is beneficial to reducing the manufacturing difficulty of the conductive contact structure 50 and improving the yield of the back contact battery 100.

[0073] Embodiment 7

[0074] See also Figure 1 and Figure 2 In some optional embodiments, the width of the insulating dielectric layer 60 in the first direction is greater than the width of the second dielectric layer 82 .

[0075] In this way, the insulating dielectric layer 60 can cooperate with the first insulating layer 40 to cover and shield the first doped layer 20. At the same time, the insulating dielectric layer 60 can also partially extend into the protruding portion 51 along the first direction, so that the first doped layer 20 can be electrically connected to the protruding portion 51 while avoiding contact with the covering portion 52, thereby improving the stability of the conductive contact structure 50.

[0076] Embodiment 8

[0077] See also Figure 1 and Figure 2 In some optional embodiments, the extension portion 51 also includes a first side 511 and a second side 512 arranged along the thickness direction, the first side 511 is a side close to the protrusion 122, the first side 511 contacts the second dielectric layer 82, and the second side 512 is a side close to the first groove 121.

[0078] In this embodiment, one side of the insulating dielectric layer 60 close to the first trench 121 protrudes from the first side 511, the top of the first side 511 is the insulating dielectric layer 60, and the bottom of the first side 511 extends into the first trench 121. The first side 511 is attached to the surface of the second dielectric layer 82, and the first doped layer 20 forms a leakage point at the first side 511 through the second dielectric layer 82.

[0079] Embodiment 9

[0080] See also Figure 1 and Figure 2In some optional embodiments, the back contact battery 100 further includes a second insulating layer 70, the second insulating layer 70 includes a first insulating portion 71, a second insulating portion 72 and a third insulating portion 73 connected in sequence, the first insulating portion 71 is stacked on the covering portion 52, the second insulating portion 72 is arranged on a side of the second side 512 close to the first groove 121, and the third insulating portion 73 is stacked on the second doping layer 30.

[0081] In this way, the second insulating layer 70 can protect the covering portion 52 , the protruding portion 51 and the second doping layer 30 in sequence through the first insulating portion 71 , the second insulating portion 72 and the third insulating portion 73 to prevent the conductive contact structure 50 and the second doping layer 30 from being exposed.

[0082] In this embodiment, the second insulating layer 70 can be a passivation film layer, and when the first doping layer 20 is a P-type doping layer and the second doping layer 30 is an N-type doping layer, the roughness of the surface of the second doping layer 30 in contact with the first insulating portion 71 is greater than the roughness of the surface of the first doping layer 20 in contact with the first insulating portion 71, so that the bonding tension between the first insulating portion 71 and the second doping layer 30 is greater than the bonding tension between the first insulating portion 71 and the first doping layer 20, thereby effectively avoiding the first solder joint from detaching during welding and improving the reliability of welding.

[0083] In some embodiments, the passivation film layer may include at least one of a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, an intrinsic amorphous silicon film layer, and a TCO film layer, and the specific details are not limited here.

[0084] Embodiment 10

[0085] See also Figure 1 and Figure 2 In some optional embodiments, the first doping layer 20 further includes a protruding portion 25 extending along the first direction to above the first trench 121 , and the second dielectric layer 82 surrounds the protruding portion 25 .

[0086] In this way, the first doping layer 20 can form a larger contact area with the protruding portion 51 through the protruding portion 25, thereby improving the conductive efficiency and quickly eliminating the influence of the hot spot.

[0087] In the embodiment of the present application, the shape of the protrusion 25 is not limited to meet different needs. For example, the end of the protrusion 25 close to the first groove 121 crosses to form a tip, and the closer to the first groove 121, the sharper the end of the protrusion 25. For another example, the end of the protrusion 25 close to the first groove 121 can be rectangular. At this time, the width of the second dielectric layer 82 along the thickness direction of the silicon substrate 10 is smaller than the width of the second dielectric layer 82 along the first direction, so that the first doped layer 20 is closer to the extension 51 in the thickness direction, and the first doped layer 20 can form a leakage point at this position, further improving safety.

[0088] Please combine Figure 3 In some embodiments, the second dielectric layer 82 includes a first region 821 and a second region 822 connected together, the first region 821 extends along the first direction, and the second region 822 extends along the thickness direction. The top of the second region 822 is the insulating dielectric layer 60, the two sides of the second region 822 are the second doping layer 30 and the first side 511, respectively, and the bottom of the second region 822 is connected to the first region 821. The top of the first region 821 is at least partially in contact with the first doping layer 20, and the bottom of the first region 821 is at least partially in contact with the extension 51, that is, a leakage point can also be formed at the position of the first region 821 to eliminate hot spots.

[0089] Specifically, the side surface of the protruding portion 25 along the first direction is the second region 822, and the bottom surface of the protruding portion 25 along the thickness direction is the first region 821. The first region 821 and the second region 822 are provided with part of the second dielectric layer 82, or in other words, a part of the second dielectric layer 82 can be provided in the first region 821, and another part of the second dielectric layer 82 can be provided in the second region 822.

[0090] In some embodiments, the thickness of the first region 821 in the thickness direction is thinner than the width of the second region 822 in the first direction, that is, the distance between the first doping layer 20 and the extension 51 is closer in the first region 821, so that the leakage point formed by the first region 821 has higher conductivity efficiency and better safety.

[0091] Please combine Figure 4 In some embodiments, the first doped layer 20 further includes a retracted region 26 retracted along the first direction to above the convex portion 122, and the second dielectric layer 82 is correspondingly disposed in the retracted region 26. In this way, the first doped layer 20 can form a larger contact area with the protruding portion 51 through the retracted region 26, thereby improving the conductive efficiency and quickly eliminating the influence of the hot spot.

[0092] Embodiment 11

[0093] See also Figure 1 and Figure 2 In some optional embodiments, the thickness of the first sub-doping layer 32 in the thickness direction is greater than the thickness of the second sub-doping layer 33 .

[0094] In this way, the thickness of the first sub-doping layer 32 and the second sub-doping layer 33 closer to the silicon substrate 10 is greater, so that the silicon substrate 10 is more stable, has a better passivation effect, a better refractive index, and a higher efficiency in receiving light.

[0095] In other embodiments, the second doping layer 30 may further include multiple other sub-doping layers, all of which are stacked, and barrier layers 34 are formed between different sub-doping layers. In the embodiments of the present application, the number of sub-doping layers is not limited, and it is only necessary to ensure that the sub-doping layer closer to the silicon substrate 10 is thicker to meet different requirements.

[0096] Embodiment 12

[0097] See also Figure 1 and Figure 2 In some optional embodiments, the thickness of the first sub-doping layer 32 in the thickness direction is 50nm-300nm; the thickness of the second sub-doping layer 33 in the thickness direction is 30nm-200nm.

[0098] For example, the thickness of the first sub-doping layer 32 in the thickness direction may be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm. The thickness of the second sub-doping layer 33 in the thickness direction may be 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm. The thickness of the first sub-doping layer 32 and the second sub-doping layer 33 in the thickness direction is set within this range, which not only ensures the basic function of the first doping layer 20 but also reduces the difficulty of preparation.

[0099] In the embodiment of the present application, the thickness of the first sub-doping layer 32 and the second sub-doping layer 33 is not specifically limited, and it is only necessary that the thickness of the first sub-doping layer 32 in the thickness direction is greater than the thickness of the second sub-doping layer 33 .

[0100] In one example, the thickness of the first sub-doped layer 32 in the thickness direction may be 200 nm, and the thickness of the second sub-doped layer 33 in the thickness direction may be 100 nm. In this way, the second doped layer 30 can be kept within a suitable thickness range, and the number of leakage points can be increased while being thin and light in cooperation with the extension portion 51, thereby improving the safety of the back contact battery 100.

[0101] Embodiment 13

[0102] See also Figure 1 and Figure 2 In some optional embodiments, the first doping layer 20 further includes a first inner expansion layer 21 formed in the protrusion 122 , and the second doping layer 30 further includes a second inner expansion layer 31 formed in the first groove 121 .

[0103] In this way, the first doped layer 20 can form a first inner expansion layer 21 on the side of the first dielectric layer 81 close to the silicon substrate 10 through a diffusion process toward the silicon substrate 10, and the second doped layer 30 can form a second inner expansion layer 31 on the side of the third dielectric layer 83 close to the silicon substrate 10 through a diffusion process toward the silicon substrate 10. The combination of the inner expansion layer, the tunneling oxide layer and the polysilicon layer further improves the efficiency and stability of the battery.

[0104] In this embodiment, the thickness of the extension portion 51 in the thickness direction of the silicon substrate 10 is greater than the total thickness of the convex portion 122, the first inner expansion layer 21, the first doping layer 20 and the first insulating layer 40. In other words, the side of the first inner expansion layer 21 close to the first groove 121 is in contact with the second dielectric layer 82, and the second dielectric layer 82 is electrically connected to the extension portion 51. The first inner expansion layer 21 and the extension portion 51 can form a new leakage point. The first inner expansion layer 21 and the second doping layer 30 can release electrical energy through the extension portion 51, so as to reduce or even eliminate the influence of hot spots, and further improve the power generation efficiency and safety of the back contact battery 100.

[0105] Embodiment 14

[0106] See also Figure 1 In some optional embodiments, the second doping layer 30 further includes a barrier layer 34 , and the barrier layer 34 is stacked between the first sub-doping layer 32 and the second sub-doping layer 33 .

[0107] Specifically, a barrier layer 34 may be further disposed between the first sub-doping layer 32 and the second sub-doping layer 33, the barrier layer 34 is stacked on the first sub-doping layer 32, and the second sub-doping layer 33 is stacked on a side of the barrier layer 34 away from the first sub-doping layer 32. The widths of the first sub-doping layer 32, the barrier layer 34, and the second sub-doping layer 33 in the first direction may be consistent, so that the extension portion 51 may be electrically connected to the first sub-doping layer 32, the barrier layer 34, and the second sub-doping layer 33 at the same time.

[0108] Furthermore, the barrier layer 34 plays a barrier role, and forms a doping concentration difference between the two sub-layer doping layers, which can further improve the passivation effect of the passivation contact structure of the back contact battery 100 and improve the efficiency of the back contact battery 100. In this embodiment, the doping concentration range of the doping layers on both sides of the barrier layer 34 is not limited to meet different needs.

[0109] Furthermore, when the conductive contact structure 50 and the second doping layer 30 have the same conductive type and are continuous as one, the barrier layer 34 can extend from the second doping layer 30 along the extension portion 51 and the covering portion 52 to divide the extension portion 51 and the covering portion 52 into two doping layers. At this time, the conductive contact structure 50 can also form the same two-layer structure and one barrier layer 34 as the second doping layer 30, that is, in the process of preparing the first sub-doping layer 32, the barrier layer 34 and the second sub-doping layer 33, the extension portion 51 and the covering portion 52 will also be a three-layer structure, and the three-layer structure can achieve the original function. In this way, during the preparation process, the conductive contact structure 50 and the second doping layer 30 can be prepared together, saving the preparation steps and improving the production efficiency.

[0110] Furthermore, in the thickness direction, the thickness of the barrier layer 34 is smaller than the thickness of the third dielectric layer 83. Thus, a cavity is provided in the barrier layer 34, thereby adjusting the doping concentration of the first sub-doping layer 32 and the second sub-doping layer 33.

[0111] Embodiment 15

[0112] See also Figure 5 and Figure 6 The battery string 200 provided in the embodiment of the present application includes a back-contact battery 100 as in any of the above embodiments.

[0113] In the back contact battery 100 and the battery string 200 of the embodiment of the present application, the back contact battery 100 includes a silicon substrate 10, a first doping layer 20, a first insulating layer 40, a second doping layer 30 and a conductive contact structure 50, the silicon substrate 10 has a front side 11 and a back side 12 opposite to each other, a first groove 121 and a convex portion 122 arranged along a first direction are formed on the back side 12, the first doping layer 20 is stacked on the convex portion 122, the first insulating layer 40 is stacked on the first doping layer 20, the second doping layer 30 is stacked in the first groove 121, the second doping layer 30 includes a first sub-doping layer 32 and a second sub-doping layer 33 stacked, the first sub-doping layer 32 is stacked on On the second groove 123, the second sub-doping layer 33 is stacked on the side of the first sub-doping layer 32 away from the silicon substrate 10, the second doping layer 30 has opposite polarity to the first doping layer 20, the conductive type of the conductive contact structure 50 is opposite to the conductive type of the first doping layer 20, the conductive contact structure 50 includes a protruding portion 51, the protruding portion 51 extends along the thickness direction of the silicon substrate 10, the protruding portion 51 is at least partially arranged in the first groove 121, only a part of the first doping layer 20 and only a part of the second doping layer 30 are respectively at least electrically connected to the protruding portion 51, and the thickness of the protruding portion 51 in the thickness direction is greater than the total thickness of the convex portion 122, the first doping layer 20 and the first insulating layer 40. In this way, the first doping layer 20 and the second doping layer 30 can release electrical energy through the conductive contact structure 50, and the conductive contact structure 50 can be used as a heat dissipation point to reduce or even eliminate the influence of hot spots, thereby improving the power generation efficiency and safety of the back contact battery 100. At the same time, the first sub-doped layer 32 and the second sub-doped layer 33 are both connected to the extension 51, increasing the contact area to increase the conductive efficiency. In addition, the conductive contact structure 50 can be of the same conductive type as the second doped layer 30 and be continuous as a whole, simplifying the manufacturing process of the back contact battery 100.

[0114] Specifically, the first doping layer 20 and the second doping layer 30 have opposite polarities. The first doping layer 20 and the second doping layer 30 are P-type doping and N-type doping, respectively. In some embodiments, P-type doping refers to doping with group III elements, including boron, aluminum, gallium, indium, thallium and other elements; N-type doping refers to doping with group V elements, including nitrogen, phosphorus, arsenic, antimony, bismuth and other elements, which are not specifically limited here.

[0115] In addition, in some embodiments, the first doping layer 20 and the second doping layer 30 may also be composite doping, for example, N-type doping also includes a small amount of P-type doping elements. The content of the N-type doping element in the second doping layer 30 is higher than 20% of the content of the P-type doping element to ensure that the polarity is opposite to that of the first doping layer 20.

[0116] Further, the conductive contact structure 50 has the same conductivity type as the second doping layer 30 and is opposite to the conductivity type of the first doping layer 20. The conductive contact structure 50 is not a doped region. Therefore, the conductive type of the conductive contact structure 50 is N-type doping, and the main conductive carrier is electrons. In other words, electrons are the majority carriers for N-type doping, holes are the majority carriers for P-type doping, and the conductive contact structure 50 is the same type as the N-type doping region, and is a different conductive type from the P-type doping region.

[0117] For example, in some embodiments, the first doped layer 20 may be a P-type polysilicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, which is not specifically limited herein. Similarly, the second doped layer 30 and the conductive contact structure 50 may be an N-type polysilicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, which is not specifically limited herein.

[0118] In the embodiment of the present application, the battery string 200 may be a shape in which a plurality of sheet-shaped back-contact batteries 100 are connected in series in sequence and connected by welding strips and bus bars. It is understandable that in the battery string 200, the battery string 200 may include two battery cells connected in series, three battery cells connected in series, or other larger numbers of battery cells. The number of battery cells that need to be connected in series can be determined based on actual usage. In addition, in the embodiment of the present application, the size and type of the back-contact battery 100 are not limited, and the specifications and sizes of adjacent battery cells may be the same or different to meet different needs.

[0119] In the embodiments of the present application, the specific connection method of adjacent battery cells is not limited to meet different needs. In one embodiment, the edges of two adjacent battery cells are at least partially stacked together; in another embodiment, two adjacent battery cells can be spaced apart. The spacing between two adjacent battery cells is within a suitable range, which can avoid the small operating space and high welding difficulty caused by too small spacing, and can also avoid the waste of component space and increased costs caused by too large spacing.

[0120] Embodiment 16

[0121] See also Figure 5 and Figure 6 The battery assembly 300 provided in the embodiment of the present application includes the battery string 200 as described in the above embodiment.

[0122] In the back contact battery 100, the battery string 200 and the battery assembly 300 of the embodiment of the present application, the back contact battery 100 includes a silicon substrate 10, a first doping layer 20, a first insulating layer 40, a second doping layer 30 and a conductive contact structure 50, the silicon substrate 10 has a front side 11 and a back side 12 opposite to each other, a first groove 121 and a convex portion 122 arranged along a first direction are formed on the back side 12, the first doping layer 20 is stacked on the convex portion 122, the first insulating layer 40 is stacked on the first doping layer 20, the second doping layer 30 is stacked in the first groove 121, the second doping layer 30 includes a first sub-doping layer 32 and a second sub-doping layer 33 stacked, and the first sub-doping layer 32 is stacked. The second sub-doping layer 33 is stacked on the second groove 123, and the second sub-doping layer 33 is stacked on the side of the first sub-doping layer 32 away from the silicon substrate 10. The second doping layer 30 has opposite polarity to the first doping layer 20. The conductive contact structure 50 has the opposite conductive type to the first doping layer 20. The conductive contact structure 50 includes a protruding portion 51, and the protruding portion 51 extends along the thickness direction of the silicon substrate 10. The protruding portion 51 is at least partially arranged in the first groove 121. Only a part of the first doping layer 20 and only a part of the second doping layer 30 are respectively electrically connected to the protruding portion 51. The thickness of the protruding portion 51 in the thickness direction is greater than the total thickness of the convex portion 122, the first doping layer 20 and the first insulating layer 40. In this way, the first doping layer 20 and the second doping layer 30 can release electrical energy through the conductive contact structure 50, and the conductive contact structure 50 can be used as a heat dissipation point to reduce or even eliminate the influence of hot spots, thereby improving the power generation efficiency and safety of the back contact battery 100. At the same time, the first sub-doped layer 32 and the second sub-doped layer 33 are both connected to the extension 51 to increase the contact area and improve the conductive efficiency. In addition, the conductive contact structure 50 can be of the same conductive type as the second doped layer 30 and be continuous as a whole, simplifying the manufacturing process of the back contact battery 100.

[0123] In this embodiment, multiple back-contact batteries 100 in the battery assembly 300 can be connected in series in sequence to form a battery string 200, thereby realizing the series bus output of the current. For example, the series connection of the battery cells can be achieved by setting welding strips (bus bars, interconnecting bars), conductive back plates, etc.

[0124] It is understandable that in such an embodiment, the battery assembly 300 may also include a frame, a back plate, a photovoltaic glass and an adhesive film. The adhesive film may be filled between the front 11 and the back 12 of the back contact battery 100 and the photovoltaic glass, adjacent battery cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film may be an EVA adhesive film or a POE adhesive film. The specific selection may be based on actual conditions and is not limited here.

[0125] The photovoltaic glass can cover the adhesive film on the front side 11 of the back contact cell 100. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, and it can protect the back contact cell 100 without affecting the efficiency of the back contact cell 100 as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the back contact cell 100 together, and the presence of the adhesive film can seal and insulate the back contact cell 100 and prevent water and moisture.

[0126] The back plate can be attached to the adhesive film on the back side 12 of the back contact battery 100. The back plate can protect and support the back contact battery 100, and has reliable insulation, water resistance and aging resistance. There are multiple options for the back plate, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. It can be set according to specific circumstances and is not limited here. The whole composed of the back plate, back contact battery 100, adhesive film and photovoltaic glass can be set on the frame. The frame serves as the main external support structure of the entire battery assembly 300 and can stably support and install the battery assembly 300. For example, the battery assembly 300 can be installed at the required installation position through the frame.

[0127] Embodiment 17

[0128] See also Figure 6 and Figure 7 The photovoltaic system 400 provided in the embodiment of the present application includes the battery assembly 300 as described in the above embodiment.

[0129] In the back-contact cell 100, the cell string 200, the cell assembly 300 and the photovoltaic system 400 of the embodiment of the present application, the back-contact cell 100 includes a silicon substrate 10, a first doping layer 20, a first insulating layer 40, a second doping layer 30 and a conductive contact structure 50, the silicon substrate 10 has a front side 11 and a back side 12 opposite to each other, a first groove 121 and a convex portion 122 arranged along a first direction are formed on the back side 12, the first doping layer 20 is stacked on the convex portion 122, the first insulating layer 40 is stacked on the first doping layer 20, the second doping layer 30 is stacked in the first groove 121, the second doping layer 30 includes a first sub-doping layer 32 and a second sub-doping layer 33 stacked, and the first sub-doping layer 32 is stacked on the first doping layer 20. The layer 32 is stacked on the second groove 123, the second sub-doped layer 33 is stacked on the side of the first sub-doped layer 32 away from the silicon substrate 10, the second doped layer 30 is opposite to the first doped layer 20 in polarity, the conductive contact structure 50 is opposite to the conductive type of the first doped layer 20, the conductive contact structure 50 includes a protruding portion 51, the protruding portion 51 extends along the thickness direction of the silicon substrate 10, the protruding portion 51 is at least partially arranged in the first groove 121, only a part of the first doped layer 20 and only a part of the second doped layer 30 are respectively at least electrically connected to the protruding portion 51, and the thickness of the protruding portion 51 in the thickness direction is greater than the total thickness of the convex portion 122, the first doped layer 20 and the first insulating layer 40. In this way, the first doped layer 20 and the second doped layer 30 can release electrical energy through the conductive contact structure 50, and the conductive contact structure 50 can be used as a heat dissipation point to reduce or even eliminate the influence of hot spots, thereby improving the power generation efficiency and safety of the back contact battery 100. At the same time, the first sub-doped layer 32 and the second sub-doped layer 33 are both connected to the extension 51 to increase the contact area and improve the conductive efficiency. In addition, the conductive contact structure 50 can be of the same conductive type as the second doped layer 30 and be continuous as a whole, simplifying the manufacturing process of the back contact battery 100.

[0130] In this embodiment, the photovoltaic system 400 can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system 400 are not limited to this, that is, the photovoltaic system 400 can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system 400 may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery assemblies 300. For example, multiple battery assemblies 300 may form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter to convert it into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.

[0131] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0132] In addition, the above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A back contact battery, characterized in that: include: A silicon substrate, wherein the silicon substrate has a front side and a back side opposite to each other, and a first groove and a convex portion arranged along a first direction are formed on the back side; A first doping layer stacked on the protrusion; A first insulating layer stacked on the first doping layer; A second doping layer stacked in the first trench, the second doping layer comprising a first sub-doping layer and a second sub-doping layer stacked, the first sub-doping layer stacked on the first trench, the second sub-doping layer stacked on a side of the first sub-doping layer away from the silicon substrate, and the second doping layer has a polarity opposite to that of the first doping layer; A conductive contact structure, wherein the conductive type of the conductive contact structure is opposite to the conductive type of the first doped layer, the conductive contact structure includes an extension portion, the extension portion extends along the thickness direction of the silicon substrate, the extension portion is at least partially arranged in the first groove, only a portion of the first doped layer and only a portion of the second doped layer are respectively electrically connected to at least the extension portion, and the thickness of the extension portion in the thickness direction is greater than the total thickness of the protrusion, the first doped layer and the first insulating layer.

2. The back contact cell according to claim 1, characterized in that: The conductive contact structure further includes a covering portion, which is stacked on the first insulating layer, and one end of the protruding portion away from the first groove is connected to the covering portion.

3. The back contact battery according to claim 2, characterized in that: The conductive contact structure has the same conductivity type as the second doping layer and is integrally continuous.

4. The back contact cell according to claim 2, characterized in that: The back contact cell further comprises a first dielectric layer, a second dielectric layer and a third dielectric layer, wherein the first dielectric layer is located between the first doped layer and the silicon substrate; The third dielectric layer is located between the second doped layer and the silicon substrate; The second dielectric layer is at least partially disposed in the first trench and adheres to the sidewall of the protrusion.

5. The back contact cell according to claim 4, characterized in that: The second dielectric layer extends in a thickness direction away from the silicon substrate, and the second dielectric layer is at least partially electrically connected to the first doped layer.

6. The back contact cell according to claim 5, characterized in that: The back contact cell further comprises an insulating dielectric layer, which is connected to an end of the second dielectric layer away from the silicon substrate, and a side of the insulating dielectric layer close to the protrusion is at least partially connected to the first doping layer and the first insulating layer.

7. The back contact cell according to claim 6, characterized in that: The width of the insulating dielectric layer in the first direction is greater than the width of the second dielectric layer.

8. The back contact battery according to claim 7, characterized in that: The protruding portion further includes a first side edge and a second side edge arranged along the thickness direction, the first side edge is a side close to the convex portion, the first side edge contacts the second dielectric layer, and the second side edge is a side close to the first groove.

9. The back contact battery according to claim 8, characterized in that The back contact battery also includes a second insulating layer, which includes a first insulating part, a second insulating part and a third insulating part connected in sequence, the first insulating part is stacked on the covering part, the second insulating part is arranged on the side of the second side close to the first groove, and the third insulating part is stacked on the second doping layer.

10. The back contact cell according to claim 6, characterized in that: The first doping layer further includes a protruding portion extending above the first trench along the first direction, and the second dielectric layer surrounds the protruding portion.

11. The back contact cell according to claim 1, characterized in that: The thickness of the first sub-doping layer in the thickness direction is greater than the thickness of the second sub-doping layer.

12. The back contact cell according to claim 11, characterized in that: The thickness of the first sub-doped layer in the thickness direction is 50nm-300nm; The thickness of the second sub-doping layer in the thickness direction is 30nm-200nm.

13. The back contact cell according to claim 1, characterized in that: The first doping layer further includes a first inner expansion layer formed in the protrusion, and the second doping layer further includes a second inner expansion layer formed in the first trench.

14. The back contact cell according to claim 1, characterized in that The second doping layer further includes a barrier layer, and the barrier layer is stacked between the first sub-doping layer and the second sub-doping layer.

15. A battery string, characterized in that: Comprising a back contact cell as described in any one of claims 1-14.

16. A battery assembly, characterized in that: Comprising the battery string as claimed in claim 15.

17. A photovoltaic system, characterized in that: Comprising the battery assembly as claimed in claim 16.

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