Back contact solar cell, photovoltaic module and photovoltaic system

Abstract

The utility model is applicable to the technical field of solar power generation, and provides a back contact solar cell, a photovoltaic assembly and a photovoltaic system, the back contact solar cell comprises a silicon substrate, a first tunneling layer and a first polycrystalline silicon doping layer, the back surface of the silicon substrate is provided with a plurality of first areas and second areas which are sequentially and alternately arranged along a first direction, the adjacent first region and second region are spaced by a groove, the first polycrystalline silicon doped layer and the first tunneling layer are arranged in the first region, and the edges of the silicon substrate of the first polycrystalline silicon doped layer, the first tunneling layer and the first region extend towards the center direction of an opening of the groove to form an extension part; or only the first polycrystalline silicon doping layer extends towards the center direction of the opening of the groove to form an extension part, and the extension part is provided with a hole. On the basis of ensuring the passivation and anti-attenuation effects, the holes are formed in the extension parts, so that identification and alignment of subsequent procedures are facilitated, meanwhile, the passivation polycrystalline silicon film is not influenced, and the conversion efficiency of the solar cell is ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of solar power generation, and in particular relates to a back-contact solar cell, a photovoltaic component and a photovoltaic system. Background Art

[0002] Solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. Among them, BC (Back Contact) cells are a general term for various types of crystalline silicon solar cells with back contact structures, including HPBC, TBC, HBC, etc. The back contact of BC cells means that both the emitter electrode and the base electrode are located on the back. On the one hand, the back contact cell structure transfers the emitter electrode to the back of the cell, thereby reducing or eliminating the shading loss of the front grid line and improving the cell efficiency; on the other hand, it is easy to assemble during component packaging. Since all the electrodes are on the back, the spacing between the cells can be reduced, the packaging density can be increased, and the appearance is beautiful.

[0003] In the related art, in order to solve the surface passivation problem of the groove area on the back side of the back-contact battery and reduce the hydrogen-related defects in the body region, the passivated contact area requires hydrogen-passivated tunneling layer defect states, which requires the use of a high-refractive index passivation film (such as high-refractive index SiNx) to achieve better mobile hydrogen content. Excessive hydrogen entering the substrate area will cause battery degradation.

[0004] At the same time, the passivation layer (such as AlOx) in the groove area is prone to negative charge field passivation, which will induce a surface p+ layer. A space charge area is generated at the contact between the p+ layer and the n++ layer. The recombination of this area will lead to an increase in the junction recombination current of the battery, which will lead to a decrease in battery performance. In addition, the back of the battery is divided into several areas corresponding to the positive and negative electrodes, and the morphology and structure of these areas are the same, which is easy to cause confusion and is not conducive to the identification and alignment of subsequent processes, which will affect the passivation polysilicon film and reduce the conversion efficiency. Utility Model Content

[0005] The embodiment of the utility model provides a back-contact solar cell, aiming to solve the problems of low performance and easy confusion in identification of existing back-contact solar cells.

[0006] The utility model is implemented in this way: a back contact solar cell comprises:

[0007] A silicon substrate, wherein the silicon substrate has a front side and a back side opposite to each other, and a plurality of first regions and second regions are arranged alternately in sequence along a first direction on the back side, and adjacent first regions and second regions are separated by grooves;

[0008] A first polysilicon doping layer, the first polysilicon doping layer is disposed on the silicon substrate in the first region; and

[0009] A first tunneling layer, the first tunneling layer is arranged between the first polysilicon doping layer and the silicon substrate of the first region;

[0010] The edges of the first polysilicon doped layer, the first tunnel layer and the silicon substrate in the first region all extend toward the center of the opening of the groove to form an extension portion, or only the first polysilicon doped layer extends toward the center of the opening of the groove to form an extension portion;

[0011] The extension portion is provided with a hole.

[0012] Furthermore, the hole is a blind hole or a through hole.

[0013] Furthermore, the diameter of the hole is 0.1 micrometer to 5 micrometers.

[0014] Furthermore, the length of the extension portion is 0.1 micrometer to 40 micrometers.

[0015] Furthermore, the length of the extension portion is 0.5 micrometers to 20 micrometers.

[0016] Furthermore, it also includes:

[0017] a second polysilicon doping layer, the second polysilicon doping layer being disposed on the silicon substrate in the second region; and

[0018] A second tunneling layer is provided between the second polysilicon doping layer and the silicon substrate in the second region.

[0019] Furthermore, it also includes:

[0020] A first passivation layer, the first passivation layer covers the first polysilicon doping layer, the second polysilicon doping layer and the groove;

[0021] a first electrode, the first electrode passing through the first passivation layer and connected to the first polysilicon doped layer; and

[0022] The second electrode passes through the first passivation layer and is connected to the second polysilicon doping layer.

[0023] Further, the first passivation layer includes at least one of an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbonitride oxynitride layer, a titanium oxide layer, a hafnium oxide layer, and an aluminum oxide layer.

[0024] In a second aspect, the present application also provides a photovoltaic module, comprising the back-contact solar cell as described above.

[0025] In a third aspect, the present application also provides a photovoltaic system, comprising the photovoltaic assembly as described above.

[0026] The beneficial effect of the present application lies in that the back-contact solar cell of the present application includes a silicon substrate, a first tunneling layer and a first polysilicon doped layer, the silicon substrate has a relative front and back side, the back side is provided with a plurality of first regions and second regions arranged alternately in sequence along a first direction, adjacent first regions and second regions are separated by grooves, the first polysilicon doped layer is provided on the silicon substrate of the first region, the first tunneling layer is provided between the first polysilicon doped layer and the silicon substrate of the first region, the edges of the first polysilicon doped layer, the tunneling layer and the silicon substrate of the first region all extend toward the opening center direction of the groove to form an extension portion, or only the first polysilicon doped layer extends toward the opening center direction of the groove to form an extension portion, and the extension portion is provided with a hole. By providing an extension portion, the groove opening is made smaller, and the exchange of plasma with the outside world can be reduced during the subsequent deposition of the passivation layer, so that the hydrogen content of the passivation layer can be localized. The movable oxygen content of the passivation layer in the groove is lower, and the movable oxygen content of the passivation film layer on the remaining area is higher, which can effectively improve the passivation and anti-attenuation effects. In addition, by providing a hole in the extension portion, it is beneficial to the identification and alignment of the subsequent processes, and at the same time does not affect the passivation polysilicon film, thereby ensuring the conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of an embodiment of a back contact solar cell provided by the present application;

[0028] Figure 2 is a schematic structural diagram of an embodiment of a back contact solar cell provided in the present application, in which an extension portion has a hole;

[0029] Figure 3 is a schematic structural diagram of another embodiment of a back contact solar cell provided by the present application, in which the extension portion has a hole;

[0030] Figure 4 yes Figure 3 Schematic diagram of the enlarged structure of the middle hole part;

[0031] Figure 5 It is a structural schematic diagram of an embodiment of a back contact solar cell provided by the present application, in which the first region, the first tunneling layer and the first polysilicon doped layer are all provided with extension portions;

[0032] Figure 6 It is a microscopic structural diagram of another embodiment of a back-contact solar cell provided by the present application, in which the first region, the first tunneling layer and the first polysilicon doped layer are all provided with extension portions;

[0033] Figure 7 It is a schematic structural diagram of an embodiment of a back contact solar cell provided by the present application, in which only the first polysilicon doping layer is provided with an extension portion;

[0034] Figure 8 It is a microscopic structural diagram of an embodiment of a back contact solar cell provided by the present application, in which only the first polysilicon doping layer is provided with an extension portion;

[0035] Fig. 9 is a schematic structural diagram of another embodiment of a back contact solar cell provided by the present application, in which only the first polysilicon doping layer is provided with an extension portion;

[0036] Fig.10 This is a microstructure schematic diagram of another embodiment of the back-contact solar cell provided by the present application, in which only the first polysilicon doping layer is provided with an extension portion. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, in which 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 utility model, and cannot be understood as limiting the utility model. In addition, it should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model.

[0038] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0039] 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 technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" 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 the present utility model can be understood according to specific circumstances.

[0041] In the present utility model, 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.

[0042] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the utility model. In addition, the utility model 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 utility model provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0043] The back-contact solar cell of the present application includes a silicon substrate, a first tunneling layer and a first polysilicon doped layer, the silicon substrate has a relative front side and a back side, the back side is provided with a plurality of first regions and second regions arranged alternately in sequence along a first direction, adjacent first regions and second regions are spaced by grooves, the first polysilicon doped layer is provided on the silicon substrate of the first region, the first tunneling layer is provided between the first polysilicon doped layer and the silicon substrate of the first region, the edges of the first polysilicon doped layer, the tunneling layer and the silicon substrate of the first region all extend toward the opening center direction of the groove to form an extension portion, or only the first polysilicon doped layer extends toward the opening center direction of the groove to form an extension portion, and the extension portion is provided with a hole. By providing an extension portion, the groove opening is made smaller, and the exchange of plasma with the outside world can be reduced during the subsequent deposition of the passivation layer, so that the hydrogen content of the passivation layer can be localized. The movable oxygen content of the passivation layer in the groove is lower, and the movable oxygen content of the passivation film layer on the remaining area is higher, which can effectively improve the passivation and anti-attenuation effects. In addition, by providing a hole in the extension portion, it is beneficial to the identification and alignment of the subsequent processes, and at the same time does not affect the passivation polysilicon film, thereby ensuring the conversion efficiency of the solar cell.

[0044] Embodiment 1

[0045] like Figures 1 to 10 As shown, an embodiment of the present application provides a back-contact solar cell, including a silicon substrate 100, the silicon substrate 100 having a front side and a back side opposite to each other, the back side being provided with a plurality of first regions 110 and second regions 120 alternately arranged in sequence along a first direction, and adjacent first regions 110 and second regions 120 being separated by grooves 130;

[0046] A first polysilicon doping layer 300 , the first polysilicon doping layer 300 is disposed on the silicon substrate 100 in the first region 110 ; and

[0047] A first tunneling layer 200 , wherein the first tunneling layer 200 is disposed between the first polysilicon doping layer 300 and the silicon substrate 100 of the first region 110 ;

[0048] The edges of the first polysilicon doped layer 300, the first tunneling layer 200 and the silicon substrate 100 in the first region 110 all extend toward the center of the opening of the groove 130 to form an extension portion, or only the first polysilicon doped layer 300 extends toward the center of the opening of the groove 130 to form an extension portion;

[0049] The extension portion is provided with a hole 150 .

[0050] The silicon substrate 100 is in the shape of a sheet or a plate, and has a front side and a back side opposite to each other. Usually, the front side of the silicon substrate 100 is regarded as a light-receiving side, and the back side of the silicon substrate 100 is regarded as a backlight side.

[0051] Optionally, the silicon substrate 100 may be an N-type silicon wafer or a P-type silicon wafer, without limitation. An N-type silicon wafer refers to a wafer obtained by doping an intrinsic semiconductor with a pentavalent element (such as phosphorus, arsenic, or bismuth, etc.), and a P-type silicon wafer refers to a wafer obtained by doping an intrinsic semiconductor with a trivalent element (such as boron, gallium, or indium, etc.), which will not be described in detail.

[0052] During implementation, a plurality of grooves 130 arranged at intervals are formed on the back side of the silicon substrate 100 , and the grooves 130 divide the back side into a plurality of first regions 110 and second regions 120 arranged alternately in sequence, that is, adjacent first regions 110 and second regions 120 are separated by the grooves 130 .

[0053] In some optional embodiments, the first direction is a horizontal lateral direction, such as Figure 1 As shown, the extension direction of the line segment L is the first direction, the first regions 110 and the second regions 120 are alternately arranged along the horizontal lateral direction of the silicon substrate 100, and the grooves 130 extend along the longitudinal direction to separate the adjacent first regions 110 and second regions 120.

[0054] In implementation, the first region 110 and the second region 120 are opposite doping type regions of the solar cell, respectively. For example, taking the silicon substrate 100 as an N-type silicon wafer, a trivalent element is doped on the basis of the N-type silicon wafer to obtain an emitter region, and the emitter region can be regarded as a p+ layer. Similarly, a pentavalent element is doped on the basis of the N-type silicon wafer to obtain a doped diffusion layer, and the doped diffusion layer can be regarded as an n+ layer. When the first region 110 is a p+ layer, the second region 120 is an n+ layer. Similarly, when the first region 110 is an n+ layer, the second region 120 is a p+ layer.

[0055] The first tunneling layer 200 and the first polysilicon doping layer 300 are stacked on the first region 110, wherein the edges of the first tunneling layer 200, the first polysilicon doping layer 300 and the silicon substrate 100 of the first region 110 all extend toward the center of the opening of the groove 130 to form an extension portion, that is, the first tunneling layer 200, the first polysilicon doping layer 300 and the silicon substrate 100 of the first region 110 all protrude toward the opening of the groove 130 to form an extension portion, so that the groove 130 forms a concave structure with a small opening and a large interior.

[0056] In implementation, the groove 130 and the extension on the silicon substrate 100 can be formed by a combination of grooving + etching. For example, an opening extending in the second direction is first formed on the silicon substrate 100 by mechanical or chemical etching, where the second direction is perpendicular to the first direction, and then the opening is etched by acid etching or alkali etching. Since the corrosion resistance of the first tunneling layer 200 and the first polysilicon doped layer 300 is different from that of the silicon substrate 100, usually, the corrosion resistance of the first tunneling layer 200 and the first polysilicon doped layer 300 is better than that of the silicon substrate 100. When etching the opening by acid etching or alkali etching, the silicon substrate 100 will be etched quickly, while the first tunneling layer 200 and the first polysilicon doped layer 300 are etched slowly or not at all, resulting in a reduced etching rate of the part of the silicon substrate 100 near the first tunneling layer 200 and the first polysilicon doped layer 300. Thus, the edge of the silicon substrate 100 in the first region 110 near the groove 130 bulges out to form the extension 140 of the silicon substrate 100 in the first region 110, and the first polysilicon doped layer 300 and the first tunneling layer 200 bulge out of the groove 130 to form the extension 310, as Figure 1 shown. By forming a recessed area (i.e., the groove 130) with a small opening and a large interior, the exchange of plasma with the outside during the subsequent deposition of the passivation film layer is reduced.

[0057] In some embodiments, when the silicon substrate 100 is etched by acid etching or alkali etching, the silicon substrate 100 is etched quickly, while the etching rate of the part of the silicon substrate 100 near the first tunneling layer 200 and the first polysilicon doped layer 300 is reduced, causing the sidewall of the silicon substrate 100 in the first region 110 to form an inclined wall to form the extension 140, and the first tunneling layer 200 and the first polysilicon doped layer 300 bulge near the edge of the groove 130 to form the extension 310, as Figure 5 and Figure 6 shown, thereby forming a recessed area with a small opening and a large interior.

[0058] In some possible embodiments, only the first polysilicon doped layer 300 may be provided with the extension 310. For example, an opening extending in the second direction is first formed on the silicon substrate 100 by mechanical or chemical etching, and then the opening is etched by acid etching or alkali etching. Here, the sidewall of the silicon substrate 100 in the first region 110 forms a vertical wall, and the first tunneling layer 200 and the first polysilicon doped layer 300 bulge near the groove 130. Then, the protruding first tunneling layer 200 is washed away by a subsequent cleaning process, and only the protruding part of the first polysilicon doped layer 300 is retained. That is, only the first polysilicon doped layer 300 extends towards the center of the opening of the groove 130 to form the extension 310, thereby forming a recessed area with a small opening and a large interior, as Figure 7and Figure 8 shown.

[0059] Optionally, the extension portion will make the groove 130 a structure with a small opening and a large interior, so it is necessary to control the length of the extension portion within a certain reasonable range. For example, the length of the extension portion can be designed to be 0.1 micron to 40 microns, such as 0.2 micron, 0.3 micron, 25 micron, 30 micron, 35 micron or any value between 0.1 micron and 40 micron. Preferably, the length of the extension portion is 0.5 micron to 20 microns, such as 0.6 micron, 0.7 micron, 1 micron, 5 micron, 6 micron, 7 micron, 8 micron, 9 micron, 10 micron, 11 micron, 15 micron or any value between 0.5 micron and 20 micron, without limitation. Through the above setting, the length of the extension portion is set within this reasonable range, which can avoid the length of the extension portion being too small and unable to achieve the function of effectively reducing the exchange of plasma with the outside world during the deposition of the passivation film layer, and can also avoid the length of the extension portion being too long, resulting in the opening of the groove 130 being too small and the etching process being too difficult, and can also avoid the length of the extension portion being too long, resulting in easy fracture.

[0060] When only the first polysilicon doping layer 300 is provided with the extension portion 310, only the extension portion 310 of the first polysilicon doping layer 300 is provided with a plurality of holes 150, such as Figure 7 shown.

[0061] When the first polysilicon doping layer 300, the first tunneling layer 200 and the silicon substrate 100 of the first region 110 are all provided with extension portions, for example, Figure 1 and Figure 5 In the structure shown, the first polysilicon doped layer 300 and the first tunneling layer 200 have an extension portion 310 , and the first region 110 has an extension portion 140 . At this time, both the extension portion 310 and the extension portion 140 are provided with a hole 150 .

[0062] It should be noted that the above-mentioned film layer structures are provided with extensions and the shapes of the extensions are examples of the embodiments of the present application, rather than specific limitations of the present application. In some other embodiments, other structural shapes can also be designed. For example, in some embodiments, when the silicon substrate 100 is subjected to acid etching or alkaline etching, the silicon substrate 100 is etched quickly, and the etching rate of the part of the silicon substrate 100 close to the first tunneling layer 200 and the first polysilicon doping layer 300 is reduced, so that the side wall of the silicon substrate 100 in the first region 110 becomes an inclined wall to form an extension 140, and the first tunneling layer 200 and the first polysilicon doping layer 300 protrude near the groove 130 and exceed the extension 140, and then the protruding first tunneling layer 200 is washed away through a subsequent cleaning process, and only the protruding part of the first polysilicon doping layer 300 is retained to form the extension 310, and only the hole 150 is provided in the extension 310, such as Fig. 9 and Fig.10 Shown, not limited.

[0063] In implementation, the hole 150 is a hole 150 that is punched by a laser when a laser is used to remove a film layer during the preparation process of a back-contact solar cell. For example, when a laser is used to remove a passivation layer or a BSG (Back Surface Field Silicon Wafer), the laser etches the hole 150 in the portion of the first polysilicon doped layer 300 and / or the first tunneling layer 200 located in the extension portion.

[0064] Optionally, the diameter of the hole 150 is 0.1 micrometer to 5 micrometers, for example, 0.2 micrometer, 0.5 micrometer, 1 micrometer, 2 micrometers, 3 micrometers or 4 micrometers, etc., without limitation.

[0065] In some possible embodiments, hole 150 is a blind hole or a perforation. The type of hole 150 can be a blind hole or a perforation, which is specifically determined by the duration and power of laser irradiation at the location of hole 150. For example, under fixed power conditions, the first hole 150 is irradiated with the laser for a shorter duration, resulting in the first hole 150 being a blind hole, and the second hole 150 is irradiated with the laser for a longer duration, resulting in the second hole 150 being a perforation. No further details will be given.

[0066] In the subsequent process of depositing the passivation layer, these holes 150 can further reduce the exchange of plasma in the groove 130 with the outside, so as to further improve the passivation and anti-attenuation effects.

[0067] The back-contact solar cell of the present application includes a silicon substrate 100, a first tunneling layer 200 and a first polysilicon doped layer 300. The silicon substrate 100 has a front side and a back side opposite to each other. The back side is provided with a plurality of first regions 110 and second regions 120 arranged alternately in sequence along a first direction. Adjacent first regions 110 and second regions 120 are separated by grooves 130. The first polysilicon doped layer 300 is provided on the silicon substrate 100 in the first region 110. The first tunneling layer 200 is provided between the first polysilicon doped layer 300 and the silicon substrate 100 in the first region 110. The edges of the first polysilicon doped layer 300, the first tunneling layer 200 and the first region 110 all extend toward the center direction of the opening of the groove 130 to form an extension portion, or only the first polysilicon doped layer 300 extends toward the center direction of the opening of the groove 130 to form an extension portion, and the extension portion is provided with a hole 150. By providing an extension portion, the opening of the groove 130 becomes smaller, and the exchange of plasma with the outside world can be reduced during the subsequent deposition of the passivation layer, so that the hydrogen content of the passivation layer can be localized. The movable oxygen content of the passivation layer in the groove 130 is lower, and the movable oxygen content of the passivation film layer in the remaining area is higher, which can effectively improve the passivation and anti-attenuation effects. In addition, by providing a hole 150 in the extension portion, it is beneficial to the identification and alignment of the subsequent processes, and at the same time does not affect the passivation polysilicon film, thereby ensuring the conversion efficiency of the solar cell.

[0068] In some possible embodiments, the back-contact solar cell provided by the present application further includes a second tunneling layer 400 and a second polysilicon doping layer 500;

[0069] The second polysilicon doping layer 500 is disposed on the silicon substrate 100 in the second region 120 , and the second tunneling layer 400 is disposed between the second polysilicon doping layer 500 and the silicon substrate 100 in the second region 120 .

[0070] In implementation, the first polysilicon doping layer 300 may be one of a P-type doping layer and an N-type doping layer, and the second polysilicon doping layer 500 may be the other of the P-type doping layer and the N-type doping layer. For example, in some embodiments, the first polysilicon doping layer 300 may be a P-type doping layer, and the second polysilicon doping layer 500 may be an N-type doping layer. The first tunneling layer 200 and the second tunneling layer 400 may be a tunneling oxide layer (e.g., a tunneling silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer. The first tunneling layer 200 and / or the second tunneling layer 400 include at least one of an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon oxycarbonitride layer, a titanium oxide layer, a chromium oxide layer, and an aluminum oxide layer.

[0071] In some optional embodiments, the back-contact solar cell provided in the present application also includes a first passivation layer 600, a first electrode 700 and a second electrode 800, the first passivation layer 600 covers the first polysilicon doped layer 300, the second polysilicon doped layer 500 and the groove 130, the first electrode 700 passes through the first passivation layer 600 to be connected to the first polysilicon doped layer 300, the second electrode 800 passes through the first passivation layer 600 to be connected to the second polysilicon doped layer 500, and the first electrode 700 and the second electrode 800 are both metal electrodes.

[0072] The first passivation layer 600 is a passivation anti-reflection film, which is used to improve the photoelectric conversion efficiency and stability of the solar cell, reduce surface damage and oxidation reaction of the solar cell, and extend the service life of the solar cell.

[0073] Optionally, the first passivation layer 600 includes at least one of an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbon nitride oxycarbon layer, a titanium oxide layer, a hafnium oxide layer, and an aluminum oxide layer, without limitation.

[0074] Optionally, the back side of the silicon substrate 100 may be a polished surface or a textured surface. The textured surface may be a surface with a relatively high roughness such as a velvet surface, which reduces light reflection, increases light absorption, changes the incident angle and propagation path of light, forms light traps, and increases the density of photogenerated carriers, thereby improving the photoelectric conversion rate of the battery.

[0075] Embodiment 2

[0076] In some optional embodiments, the present application also provides a photovoltaic module, comprising the back-contact solar cell as described above.

[0077] It is understandable that the photovoltaic module may also include a metal frame, a back plate, photovoltaic glass and an adhesive film (not shown in the figure), etc. Among them, the adhesive film can be filled between the front of the back contact solar cell and the photovoltaic glass, and can also be filled between the back of the back contact solar cell and the back plate, and filled between adjacent back contact solar cells. As a filler, the adhesive film can be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film can be an EVA (ethylene-vinylacetate copolymer) adhesive film or a POE (Polyolefin elastomer) adhesive film. The specific selection can be made according to actual conditions and is not limited here. Photovoltaic glass can be covered on the adhesive film on the front of the back contact solar cell. 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%, which can protect the back contact solar cell without affecting the efficiency of the back contact solar cell as much as possible. At the same time, the adhesive film can combine the photovoltaic glass and the back-contact solar cell together. The presence of the adhesive film can seal, insulate, and waterproof and moisture-proof the back-contact solar cell.

[0078] The backplane can be attached to the adhesive film on the back of the back-contact solar cell. The backplane can protect and support the back-contact solar cell and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplane, usually tempered glass, plexiglass, aluminum alloy TPT (Tedlar / PET / Tedlar, polyvinyl fluoride composite film) composite film, etc. The specific settings can be made according to the specific situation and are not limited here.

[0079] The whole composed of the back panel, back contact solar cells, adhesive film and photovoltaic glass can be set on a metal frame. The metal frame serves as the main external supporting structure of the entire photovoltaic module and can provide stable support and installation for the photovoltaic module. For example, the photovoltaic module can be installed at the required location through the metal frame.

[0080] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the photovoltaic assembly described above can refer to the corresponding structure and implementation principle in the aforementioned embodiment 1, and will not be repeated here.

[0081] The back-contact solar cell of the present application includes a silicon substrate 100, a first tunneling layer 200 and a first polysilicon doped layer 300. The silicon substrate 100 has a front side and a back side opposite to each other. The back side is provided with a plurality of first regions 110 and second regions 120 arranged alternately in sequence along a first direction. Adjacent first regions 110 and second regions 120 are separated by grooves 130. The first polysilicon doped layer 300 is provided on the silicon substrate 100 in the first region 110. The first tunneling layer 200 is provided between the first polysilicon doped layer 300 and the silicon substrate 100 in the first region 110. The edges of the first polysilicon doped layer 300, the first tunneling layer 200 and the first region 110 all extend toward the center direction of the opening of the groove 130 to form an extension portion, or only the first polysilicon doped layer 300 extends toward the center direction of the opening of the groove 130 to form an extension portion, and the extension portion is provided with a hole 150. By providing an extension portion, the opening of the groove 130 becomes smaller, and the exchange of plasma with the outside world can be reduced during the subsequent deposition of the passivation layer, so that the hydrogen content of the passivation layer can be localized. The movable oxygen content of the passivation layer in the groove 130 is lower, and the movable oxygen content of the passivation film layer in the remaining area is higher, which can effectively improve the passivation and anti-attenuation effects. In addition, by providing a hole 150 in the extension portion, it is beneficial to the identification and alignment of the subsequent processes, and at the same time does not affect the passivation polysilicon film, thereby ensuring the conversion efficiency of the solar cell.

[0082] Embodiment 3

[0083] In some optional embodiments, the present application also provides a photovoltaic system, including the above-mentioned photovoltaic component.

[0084] During implementation, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water 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 is understandable that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system 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 may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components can 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 and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0085] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the structure and implementation principle of the photovoltaic system described above can refer to the corresponding structure and implementation principle in the aforementioned embodiments one and two, and will not be repeated here.

[0086] The back-contact solar cell of the present application includes a silicon substrate 100, a first tunneling layer 200 and a first polysilicon doped layer 300. The silicon substrate 100 has a front side and a back side opposite to each other. The back side is provided with a plurality of first regions 110 and second regions 120 arranged alternately in sequence along a first direction. Adjacent first regions 110 and second regions 120 are separated by grooves 130. The first polysilicon doped layer 300 is provided on the silicon substrate 100 in the first region 110. The first tunneling layer 200 is provided between the first polysilicon doped layer 300 and the silicon substrate 100 in the first region 110. The edges of the first polysilicon doped layer 300, the first tunneling layer 200 and the first region 110 all extend toward the center direction of the opening of the groove 130 to form an extension portion, or only the first polysilicon doped layer 300 extends toward the center direction of the opening of the groove 130 to form an extension portion, and the extension portion is provided with a hole 150. By providing an extension portion, the opening of the groove 130 becomes smaller, and the exchange of plasma with the outside world can be reduced during the subsequent deposition of the passivation layer, so that the hydrogen content of the passivation layer can be localized. The movable oxygen content of the passivation layer in the groove 130 is lower, and the movable oxygen content of the passivation film layer in the remaining area is higher, which can effectively improve the passivation and anti-attenuation effects. In addition, by providing a hole 150 in the extension portion, it is beneficial to the identification and alignment of the subsequent processes, and at the same time does not affect the passivation polysilicon film, thereby ensuring the conversion efficiency of the solar cell.

[0087] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A back contact solar cell, characterized in that: include: A silicon substrate, wherein the silicon substrate has a front side and a back side opposite to each other, wherein the back side is provided with a plurality of first regions and second regions alternately arranged in sequence along a first direction, and adjacent first regions and second regions are separated by grooves; a first polysilicon doping layer, wherein the first polysilicon doping layer is disposed on the silicon substrate in the first region; as well as A first tunneling layer, wherein the first tunneling layer is disposed between the first polysilicon doping layer and the silicon substrate in the first region; The edges of the first polysilicon doped layer, the first tunneling layer and the silicon substrate in the first region all extend toward the center of the opening of the groove to form an extension portion, or only the first polysilicon doped layer extends toward the center of the opening of the groove to form the extension portion; The extension portion is provided with a hole.

2. The back contact solar cell according to claim 1, characterized in that The holes are blind holes or through holes.

3. The back contact solar cell according to claim 1 or 2, characterized in that: The diameter of the holes is 0.1 micrometer to 5 micrometers.

4. The back contact solar cell according to claim 1, characterized in that: The length of the extension portion is 0.1 micrometer to 40 micrometers.

5. The back contact solar cell according to claim 4, characterized in that The length of the extension portion is 0.5 micrometers to 20 micrometers.

6. The back contact solar cell according to claim 1, characterized in that: Also includes: a second polysilicon doping layer, wherein the second polysilicon doping layer is disposed on the silicon substrate in the second region; as well as A second tunneling layer is disposed between the second polysilicon doping layer and the silicon substrate in the second region.

7. The back contact solar cell according to claim 6, characterized in that Also includes: a first passivation layer, wherein the first passivation layer covers the first polysilicon doping layer, the second polysilicon doping layer and the groove; a first electrode, the first electrode passing through the first passivation layer and connected to the first polysilicon doping layer; as well as A second electrode is connected to the second polysilicon doping layer through the first passivation layer.

8. The back contact solar cell according to claim 7, characterized in that: The first passivation layer includes at least one of an amorphous silicon layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbon nitride oxycarbon layer, a titanium oxide layer, a hafnium oxide layer, and an aluminum oxide layer.

9. A photovoltaic module, characterized in that: A back-contact solar cell comprising the method of any one of claims 1 to 8.

10. A photovoltaic system, characterized in that: Comprising the photovoltaic module as claimed in claim 9.

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