Photovoltaic module and TBC solar cell thereof, and back structure and preparation of TBC cell

Abstract

A photovoltaic module and a TBC solar cell thereof, and a back structure and preparation of a TBC cell. According to the photovoltaic module, a central support column is connected to a frame of a solar cell panel by means of a universal rotary joint, and the solar cell panel can rotate in the direction parallel to a plane X by means of a first support rod assembly; the solar cell panel can rotate in the plane X by means of a second support rod assembly; and the design of hingedly connecting one end of a support rod to the frame enables the solar cell panel to rotate in the direction parallel to a plane Y at the same time. In addition, the solar cell of a back contact structure can be used in combination with the structural optimization of a photovoltaic module support, so as to improve the conversion performance of the solar cell.

Description

Photovoltaic modules and their TBC solar cells, back structure and preparation of TBC cells Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a photovoltaic module and a TBC solar cell thereof, and the back structure and preparation of the TBC cell. Background Art

[0002] As energy becomes increasingly scarce, solar energy, a green, clean, and renewable energy source, is attracting significant attention. As fossil energy reserves dwindle, the economic benefits and investment value of the solar energy industry are becoming increasingly prominent. Developing the photovoltaic industry is a key initiative in achieving China's "dual carbon" goals. Photovoltaic modules are a key component of photovoltaic power generation systems. Typically, photovoltaic modules are mounted on a photovoltaic module support. Multiple photovoltaic modules supporting the modules are arranged in a predetermined array and electrically connected to form a photovoltaic power generation system. To achieve higher power generation efficiency in photovoltaic power generation systems, the utilization rate of solar radiation is often improved, for example by optimizing the structure of the photovoltaic module support.

[0003] To ensure installation stability, photovoltaic module mounting systems are primarily based on fixed mounting methods. This arrangement maintains a fixed mounting angle for the photovoltaic modules, making the installation relatively stable but preventing optimal utilization of sunlight. Furthermore, mounting methods that enable single-axis adjustment are gradually emerging, allowing the photovoltaic modules to adjust their orientation based on the sun's azimuth. However, these photovoltaic modules still face technical challenges in terms of stability and solar radiation utilization, which require improvement.

[0004] In addition, one form of solar cell that makes up the solar panel is the IBC cell (Interdigitated back contact solar cell), which is the abbreviation of interdigitated back contact solar cell. Thanks to its front-side grid-free design and the advantage of the interdigitated junction cross arrangement of the positive and negative electrodes on the back, the IBC cell is one of the most promising and efficient solar cell structures for silicon-based solar cells. In order to further improve the conversion efficiency of IBC solar cells, researchers usually combine the tunneling oxide polysilicon passivated contact (Tunneling Oxide Passivated Contact) and IBC to form a tunneling oxide polysilicon passivated contact interdigitated back contact solar cell (Tunneling Oxide passivated and interdigitated back contact), referred to as TBC cell.

[0005] However, the existing TBC battery preparation method usually involves multi-step masking and wet etching, which leads to continuous thinning of silicon wafers during the manufacturing process, resulting in performance degradation and the introduction of contamination. In particular, the doped polysilicon layer used for the interdigitated structure will overlap on the back side, and poor process control will cause leakage of the battery cell. Secondly, the boron-doped polysilicon layer needs to be thicker to meet the passivation and contact requirements. The above problems have caused TBC batteries to still have technical risks and high costs in terms of process implementation and structure.

[0006] Summary of the Invention

[0007] 1. Problem to be solved

[0008] One of the purposes of the present invention is to provide a photovoltaic module that can easily and simply adjust the azimuth and elevation angles of solar panels, thereby improving the utilization rate of solar radiation and having good stability.

[0009] Another object of the present invention is to provide a back contact structure of a TBC solar cell, aiming to improve the conversion efficiency of the solar cell; at the same time, the present invention also provides the TBC solar cell and a preparation process of the solar cell.

[0010] 2. Technical solution

[0011] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0012] According to a first aspect of the present invention, a back contact structure of a solar cell is provided, in particular a TBC solar cell. The TBC solar cell can be applied to a solar panel. The back contact structure includes:

[0013] A passivation layer disposed on the back side of the base silicon wafer, a dielectric layer disposed on the passivation layer, and an electrode penetrating the dielectric layer and contacting the passivation layer; the "passivation layer" mentioned herein includes a "tunneling oxide layer" disposed on the back side of the base silicon wafer and a "doped polysilicon layer" disposed on the tunneling oxide layer;

[0014] The passivation layer includes a first passivation layer, a second passivation layer having a polarity opposite to that of the first passivation layer, and an isolation region between the first passivation layer and the second passivation layer;

[0015] The electrodes include a first electrode and a second electrode, the first electrode passes through the dielectric layer and contacts the first passivation layer, and the second electrode passes through the dielectric layer and contacts the second passivation layer;

[0016] Wherein, the isolation region includes a first inclined surface and a second side surface;

[0017] The first inclined surface is formed on the first passivation layer;

[0018] The second side surface is formed on the second passivation layer;

[0019] The bottom of the first inclined surface and the bottom of the second side surface intersect at a surface close to the base silicon wafer, and starting from the intersection, the first inclined surface extends outward to contact the dielectric layer, and the second side surface extends outward to contact the dielectric layer, and the first inclined surface and the second side surface have an angle of 5 to 60 degrees.

[0020] That is, it can be understood that the "intersection region formed by the intersection" exists in the "tunneling oxide layer" of the "passivation layer" as mentioned above rather than on the base silicon wafer.

[0021] According to any embodiment of the back contact structure of a TBC solar cell according to the first aspect of the present invention, the first inclined surface has a greater inclination than the second side surface. Furthermore, the first inclined surface extends outward to a point of contact with the dielectric layer.

[0022] The second side surface extends outwardly to a contact point with the dielectric layer;

[0023] The vertical projection distance between the two contact points in the direction of the base silicon wafer is 20-100 μm.

[0024] According to the back contact structure of the TBC solar cell of any embodiment of the first aspect of the present invention, the depth of the isolation region on the base silicon wafer does not exceed 0.5 microns;

[0025] Preferably, the isolation region does not form contact with the base silicon wafer.

[0026] According to the back contact structure of the TBC solar cell of any embodiment of the first aspect of the present invention, the surface of the first inclined surface has a pyramid or inverted pyramid structure;

[0027] and / or, the surface of the second vertical surface has a pyramid-shaped or inverted pyramid-shaped structure;

[0028] The size of the pyramid is between 30-100 nm.

[0029] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the first passivation layer comprises: a bottom passivation layer in direct contact with the back side of the base silicon wafer;

[0030] a top passivation layer stacked on the bottom passivation layer;

[0031] The bottom passivation layer and the top passivation layer have the same polarity;

[0032] The first electrode contacts the top passivation layer through the dielectric layer.

[0033] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the bottom passivation layer and the second passivation layer contain the same doping impurities but have opposite polarities.

[0034] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the top passivation layer includes a tunneling oxide layer and a doped polysilicon layer; the bottom passivation layer includes a tunneling oxide layer and a doped polysilicon layer; and the second passivation layer includes a tunneling oxide layer and a doped polysilicon layer.

[0035] According to the back contact structure of the TBC solar cell of any embodiment of the first aspect of the present invention, the doped polysilicon layer has a thickness of 30 to 300 nm, preferably a thickness of 100 to 300 nm;

[0036] According to the back contact structure of the TBC solar cell of any embodiment of the first aspect of the present invention, the doped polysilicon layer of the top passivation layer has a thickness of 3E19cm -3 ~10E19cm -3 doping concentration.

[0037] According to the back contact structure of the TBC solar cell of any embodiment of the first aspect of the present invention, the doped polysilicon layer of the bottom passivation layer has a thickness of 3E19cm -3 ~10E19cm -3 doping concentration.

[0038] According to the back contact structure of the TBC solar cell of any embodiment of the first aspect of the present invention, the doped polysilicon layer of the second passivation layer has a thickness of 3E20cm -3 ~10E20cm -3 doping concentration.

[0039] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the tunneling oxide layer has a thickness of 0.5-3 nm.

[0040] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the dielectric layer includes one or more combinations of an oxide layer, a silicon nitride layer, and an amorphous silicon layer.

[0041] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the dielectric layer has a thickness of 3 to 90 nm.

[0042] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the dielectric layer includes an oxide layer in contact with the passivation layer;

[0043] and, a silicon nitride layer in contact with the oxide layer;

[0044] wherein the oxide layer has a thickness of 3 to 10 nm;

[0045] The silicon nitride layer has a thickness of 50 to 80 nm.

[0046] According to the back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, the dielectric layer has a refractive index of 1.9-2.1.

[0047] According to the purpose of the present invention, the second aspect of the present invention provides a method for preparing a back contact structure of a TBC solar cell according to any embodiment of the first aspect of the present invention, comprising:

[0048] Step S1: polishing the surface of the base silicon wafer;

[0049] Step S2: depositing a bottom tunneling oxide layer, a bottom amorphous silicon layer, and a doped silicon oxide layer on the surface treated in step S1, and performing diffusion doping and crystallization by thermal diffusion;

[0050] Step S3: removing the doped silicon oxide layer in the first region and retaining the doped silicon oxide layer in the second region;

[0051] Step S4: depositing an oxide layer, a top non-doped polysilicon layer, and a doped silicon oxide layer on the surface of the first region treated in step S3; and thermally advancing the doping impurities of the doped silicon oxide layer toward the bottom tunneling oxide layer, thereby forming an inversion between the bottom tunneling oxide layer and the bottom polysilicon layer.

[0052] Simultaneously, the surface concentration of the doped silicon oxide layer in the second region is increased; wherein the coverage area of ​​the doped silicon oxide layer is smaller than the coverage area of ​​the top undoped polysilicon layer;

[0053] Step S5: etching the top doped polysilicon layer deposited on the surface of the first region to form an isolation region having a first slope;

[0054] Step S6: depositing an oxide and a hydrogenated silicon nitride layer on the surface of the base silicon wafer;

[0055] Step S7: Printing to form the first and second electrodes, and sintering to form ohmic contacts.

[0056] As described herein, the first and second electrodes are metal electrodes, and the metal electrodes include any one or two or more of a silver electrode, a copper electrode, an aluminum electrode, a tin-clad copper electrode, and a silver-clad copper electrode.

[0057] According to the purpose of the present invention, a third aspect of the present invention provides a TBC solar cell, the cell comprising a base silicon wafer;

[0058] A back contact structure is provided on the back side of the base silicon wafer, wherein the back contact structure is such as the back contact structure of a TBC solar cell according to any embodiment of the first aspect, or the back contact structure of a TBC solar cell prepared by the method of any embodiment of the second aspect; and a second dielectric layer is provided on the front side of the base silicon wafer.

[0059] According to the TBC solar cell of any embodiment of the third aspect of the present invention, the second dielectric layer includes one or more combinations of an oxide layer, a silicon nitride layer, and an amorphous silicon layer.

[0060] According to the TBC solar cell of any embodiment of the third aspect of the present invention, the second dielectric layer includes an oxide layer and a silicon nitride layer.

[0061] According to the TBC solar cell of any embodiment of the third aspect of the present invention, the second dielectric layer has a thickness of 3 to 90 nm.

[0062] According to the purpose of the present invention, a fourth aspect of the present invention provides a method for preparing a TBC solar cell according to any embodiment of the third aspect of the present invention, comprising: step A1: polishing the surface of the base silicon wafer;

[0063] Step A2: depositing a bottom tunneling oxide layer, a bottom amorphous silicon layer, and a doped silicon oxide layer on the surface treated in step A1, and performing diffusion doping and crystallization by thermal diffusion;

[0064] Step A3: removing the doped silicon oxide layer in the first region and retaining the doped silicon oxide layer in the second region;

[0065] Step A4: depositing an oxide layer, a top non-doped polysilicon layer, and a doped silicon oxide layer on the surface of the first region treated in step A3; and thermally advancing the doping impurities in the doped silicon oxide layer toward the bottom tunneling oxide layer, thereby forming an inversion between the bottom tunneling oxide layer and the bottom polysilicon layer.

[0066] Simultaneously, the surface concentration of the doped silicon oxide layer in the second region is increased; wherein the coverage area of ​​the doped silicon oxide layer is smaller than the coverage area of ​​the top undoped polysilicon layer;

[0067] Step A5: Using a single-sided film removal method, remove the hybrid structure grown on the front side of the base silicon wafer;

[0068] Step A6: texturing the front surface of the base silicon wafer processed in step A5; at the same time, etching the top doped polysilicon layer deposited on the surface of the first region to form an isolation region having a first slope;

[0069] Step A7: depositing an oxide and a hydrogenated silicon nitride layer on the surface of the base silicon wafer;

[0070] Step A8: Printing and forming the first and second electrodes on the back side of the base silicon wafer, and sintering them to form ohmic contacts.

[0071] According to a fifth aspect of the present invention, a photovoltaic assembly is provided, comprising a solar panel and a photovoltaic assembly bracket for supporting the solar panel; the photovoltaic assembly bracket comprises: a frame for fixing the solar panel;

[0072] a central pillar connected to the frame via a universal rotating joint;

[0073] A first support rod assembly, comprising a connecting rod and a rotating rod, one end of the connecting rod being connected to the central pillar and being rotatable in a plane Y parallel to the length direction of the central pillar, the other end of the connecting rod being hinged to one end of the rotating rod, and the other end of the rotating rod being connected to the frame via an annular guide rail slider assembly having a positioning function;

[0074] A second support rod assembly, the second support rod assembly comprising a support rod, one end of the support rod being connected to the central pillar and being rotatable in a plane X perpendicular to the plane Y, and one end of the support rod being hinged to the frame;

[0075] According to any embodiment of the photovoltaic assembly support of the fifth aspect of the present invention, the solar cell panel includes a solar cell, and the solar cell includes the solar cell provided by any embodiment of the third aspect of the present invention, or the solar cell provided by any embodiment of the fourth aspect of the present invention.

[0076] According to the photovoltaic component support described in any embodiment of the fifth aspect of the present invention, the height of the central pillar is adjustable; the length of the connecting rod is adjustable; the length of the rotating rod is adjustable; and the length of the support rod is adjustable.

[0077] According to the photovoltaic component bracket described in any embodiment of the fifth aspect of the present invention, the annular guide rail slider assembly with a positioning function includes a slider and an annular guide rail; the annular guide rail is formed around the connection between the central pillar and the frame; the rotating rod is hinged to the slider. Beneficial effects

[0078] (1) The photovoltaic assembly provided by the present invention has a central pillar connected to the frame of the solar panel via a universal rotary joint, and the support rod assembly 1 is connected to the frame via an annular guide rail slider assembly with a positioning function, which can realize the rotation of the solar panel in a direction parallel to the plane X. One end of the support rod of the support rod assembly 2 is connected to the central pillar via a sleeve bearing structure, so that the support rod assembly 2 cooperates with the support rod assembly 1 to realize the rotation of the solar panel in plane X. At the same time, the design of the hinged connection between one end of the support rod and the frame can realize the rotation of the solar panel in a direction parallel to the plane Y at the same time.

[0079] (2) The photovoltaic assembly provided by the present invention has a height of the core pillar, a length of the connecting rod of the support rod assembly 1, a length of the rotating rod, and a length of the support rod of the support rod assembly 2 that can be adjusted, thereby enabling adjustment of the height of the solar cell panel.

[0080] (3) The back contact structure of the TBC solar cell provided by the present invention has a channel isolation region with an inclined surface in the back interdigitated PN contact region, which prevents carriers from passing through the PN junction at the side, thereby avoiding the risk of short circuit and achieving the effect of suppressing leakage;

[0081] At the same time, in the area of ​​the first electrode, a multi-layer tunnel oxide layer is superimposed on a multi-layer polysilicon passivation technology, so that the passivation effect is better than the conventional single-layer passivation capability.

[0082] (4) Compared with the isolation region formed by conventional polishing grooves in the prior art (as shown in FIG19 , the cross-sectional shape of the isolation region is close to a rectangle, that is, both sides are nearly perpendicular to the surface of the silicon wafer base), the back contact structure of the TBC solar cell provided by the present invention has an isolation region with an angle of 5 to 60°, and the cross-sectional shape of the isolation region is closer to a sharp angle, and the inclination of the first inclination of the isolation region is greater than the inclination of the second side surface. Based on this, the first inclination and the angle of the isolation region can expose the side wall of the isolation region, so that the inclination of the isolation region can be effectively formed during the deposition of the surface passivation film, and at the same time, the long-wave light passing through the battery can be further reflected and refracted, so that it can be absorbed and utilized by the base silicon wafer; so that the TBC solar cell provided by the invention has the advantages of high open circuit voltage, large short-circuit current and small reverse current. Finally, the Voc and Jsc of the TBC solar cell provided by the present invention are effectively improved; at the same time, when the battery is in the reverse bias state of -15V, the dark state current can be controlled within 0.1A.

[0083] (5) The back contact structure of the TBC solar cell provided by the present invention has an isolation region whose depth is substantially consistent with the thickness of the stacked layer on the surface of the base silicon wafer. Furthermore, since the depth of the isolation region on the base silicon wafer does not exceed 0.5 μm, or even the isolation region does not form contact with the base silicon wafer, the base silicon wafer can better absorb sunlight without causing the base silicon wafer to be excessively exposed.

[0084] (6) The method for preparing a TBC solar cell provided by the present invention utilizes the difference in reaction rates of polysilicon with different doping characteristics in the first region and the second region of the base silicon wafer in an alkaline solution, and can spontaneously form a channel with an inclined surface as an isolation region during the wet texturing in step A6, thereby achieving isolation of the PN electrode and significantly reducing the difficulty of preparation.

[0085] The depth of the isolation region obtained by the method of the present invention can be basically consistent with the thickness of the stacked layer on the surface of the base silicon wafer, and since the depth of the isolation region on the base silicon wafer does not exceed 0.5 microns, or even the isolation region does not form contact with the base silicon wafer, the performance of the component product finally made of the TBC battery in terms of mechanical load can be improved, which is significantly better than the conventional polishing groove shown in Figure 20 in the current prior art (the corrosion depth of the base silicon wafer is about 2-3 microns).

[0086] (7) The preparation method of the TBC solar cell provided by the present invention is compared with the isolation area formed by the conventional polishing groove in the prior art (as shown in Figures 19 and 20, the overall shape of the isolation area is close to a rectangle, that is, both sides are nearly perpendicular to the surface of the silicon wafer base area). The velvet passivation has a differential polishing surface, and the two vertical polishing surfaces it has make it difficult to deposit a dielectric layer on its side edges, and the deposition effect of the dielectric layer thereon cannot be guaranteed. The isolation area with a polished bevel spontaneously formed by the method of the present invention can better guarantee the deposition effect of the dielectric layer thereon, such as the deposition thickness, due to its shallow depth, smooth surface, and the effect of the bevel, thereby achieving better surface passivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] FIG1 is a schematic diagram of the back contact structure of a TBC solar cell provided by Example 2 of the present invention;

[0088] FIG2 is a schematic diagram of the isolation region of the back contact structure of a TBC solar cell provided by Example 2 of the present invention;

[0089] FIG3 is a schematic diagram of the isolation region of the back contact structure of a TBC solar cell provided by Example 2 of the present invention;

[0090] FIG4 is a schematic structural diagram of a TBC solar cell provided in Example 3 of the present invention;

[0091] 5 to 11 are schematic diagrams of the preparation process of the TBC solar cell back contact structure provided in Example 2 of the present invention;

[0092] 12 to 18 are schematic diagrams of the preparation process of the TBC solar cell structure provided in Example 4 of the present invention;

[0093] FIG19 is a schematic structural diagram of a TBC-D3 solar cell provided in a comparative example of the present invention;

[0094] FIG20 is a schematic structural diagram of a TBC-D7 solar cell provided in a comparative example of the present invention;

[0095] FIG21 is a schematic diagram illustrating the structure of the isolation region of the back contact structure of a TBC solar cell provided by the present invention;

[0096] FIG22 is a schematic diagram illustrating the structure of the isolation region of the back contact structure of a TBC solar cell provided by the present invention;

[0097] FIG23 is a schematic structural diagram of a photovoltaic module provided in Example 1 of the present invention;

[0098] FIG24 is a schematic diagram of the back structure of the photovoltaic module frame provided in Example 1 of the present invention;

[0099] In the figure: 100, base silicon wafer; 110, velvet structure; 200, first passivation layer; 210, bottom passivation layer; 211, bottom tunneling oxide layer; 212, bottom doped polysilicon layer; 220, top passivation layer; 221, top tunneling oxide layer; 222, top doped polysilicon layer; 230, first electrode; 300, second passivation layer; 311, second tunneling oxide layer; 312, second doped polysilicon layer; 320, second electrode; 400, isolation region; 410, first inclined plane; 420, first side surface; 430, intersection region; 500, second dielectric layer; 510, second oxide layer; 520, second silicide layer; 600, first dielectric layer; 610, first oxide layer; 620, first silicide layer; 001, tunneling oxide layer; 002, Doped polysilicon layer; 003, doped silicon oxide layer; 004, non-doped polysilicon area; 01, first area; 02, second area; 700, photovoltaic module bracket; 710, frame; 720, base; 730, central pillar; 731, universal rotary joint; 740, support rod assembly one; 741, connecting rod; 742, rotating rod; 750, annular guide rail slider assembly with positioning function; 751, slider; 752, annular guide rail; 760, support rod assembly two; 761, support rod; 762, sleeve; 800, solar panel. DETAILED DESCRIPTION

[0100] The present disclosure may be more readily understood by reference to the following description in conjunction with the accompanying drawings and examples, all of which constitute a part of this disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions, or parameters described and / or illustrated herein. Further, the terms used herein are for the purpose of describing specific embodiments by way of example only and are not intended to be limiting unless otherwise indicated.

[0101] It should also be understood that, for the sake of clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically not included, each separate embodiment is considered to be combinable with any other embodiment, and the combination is considered to represent another different embodiment. Conversely, for the sake of simplicity, various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or sub-structure itself may also be considered to be an independent embodiment.

[0102] Unless otherwise indicated, it should be understood that each individual element in a list and each combination of individual elements in that list will be interpreted as a different embodiment. For example, a list of embodiments expressed as "A, B, or C" should be interpreted to include embodiments "A," "B," "C," "A or B," "A or C," "B or C," or "A, B, or C."

[0103] In this disclosure, the singular forms of the articles "a," "an," and "the" also include the corresponding plural reference, and a reference to a specific value includes at least that specific value unless the context clearly dictates otherwise. Thus, for example, a reference to "a substance" is a reference to at least one of that substance and equivalents thereof.

[0104] Terms including ordinal numbers such as "first" and "second" may be used to explain various components or fluids, but these components and fluids are not limited by these terms. Therefore, without departing from the teachings of the present disclosure, these terms are only used to distinguish the component / fluid from another component / fluid.

[0105] When items are described by using conjunction terms such as “… and / or…”, the description should be understood to include any one of the associated listed items and all combinations of one or more thereof; for example, A and / or B should be interpreted as including an embodiment that includes “A” but not “B”, an embodiment that includes “B” but not “A”, and an embodiment that includes both “A” and “B”.

[0106] Throughout the specification of this application document, when a part is described as “including” a certain constituent element, unless otherwise clearly described to the contrary, it does not mean that other constituent elements are excluded, but rather that other constituent elements may be included.

[0107] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains; any and all combinations of terms and / or terms used herein include one or more of the listed items. In order to illustrate the technical solutions and advantages of the present invention, the following is a complete description of the technical solutions in the embodiments of the present invention.

[0108] Example 1

[0109] As shown in FIG. 23 , a photovoltaic assembly is provided in this embodiment. The photovoltaic assembly includes a solar cell panel 800 and a photovoltaic assembly bracket 700 for supporting the solar cell panel 800 .

[0110] The photovoltaic module support 700 includes a base 720 and a central support 730 mounted on the base 720. The photovoltaic module support 700 also includes a frame 710 and a support rod assembly 1 740 and a support rod assembly 2 760 for cooperating with the central support 730 to adjust the angle of the solar panel 800.

[0111] The frame 710 is used to fix the solar cell panel 711 .

[0112] The central support 730 is connected to the frame 710 via a universal rotary joint 731. It should be noted that the height of the central support 730 is adjustable.

[0113] The support rod assembly 740 includes a connecting rod 741 and a rotating rod 742. One end of the connecting rod 741 is hinged to the central pillar 730, so that the connecting rod 741 can rotate in a plane Y parallel to the length direction of the central pillar 730; the other end of the connecting rod 741 is hinged to one end of the rotating rod 742, and the other end of the rotating rod 742 is connected to the frame 710 through an annular guide rail slider assembly 750 with a positioning function.

[0114] As shown in FIG24 , the annular guide rail slider assembly 750 with positioning function described herein includes a slider 751 and an annular guide rail 752. The annular guide rail 752 is mounted on the back of the frame 710 and surrounds the connection point O between the central support 730 and the frame 710. The rotating rod 742 is hingedly connected to the slider 751. It is further clarified that the lengths of the connecting rod 741 and the rotating rod 742 are adjustable.

[0115] The second support rod assembly 760 includes a support rod 761. One end of the support rod 761 is connected to the central pillar 730 via a sleeve 762 (bearing) structure, allowing the support rod 761 to rotate in a plane X perpendicular to the plane Y. The support rod 761 and the sleeve 762 are also hinged. The other end of the support rod 761 is hinged to the frame 710. In addition, the length of the support rod 761 is adjustable.

[0116] Example 2

[0117] An embodiment of the present invention provides a back contact structure for a TBC solar cell. The TBC solar cell can be applied to the solar cell panel 800 described in the present invention to form a photovoltaic module. For ease of illustration, only portions relevant to the embodiment of the present invention are shown, with reference to Figures 1, 2, and 5 to 11.

[0118] The back contact structure of a TBC solar cell provided by an embodiment of the present invention includes:

[0119] A passivation layer disposed on the back side of the base silicon wafer 100, a first dielectric layer 600 disposed on the passivation layer, and an electrode passing through the first dielectric layer 600 and in contact with the passivation layer;

[0120] The passivation layer includes a first passivation layer 200, a second passivation layer 300 having a polarity opposite to that of the first passivation layer 200, and an isolation region 400 located between the first passivation layer 200 and the second passivation layer 300;

[0121] The electrodes include a first electrode 230 and a second electrode 320, the first electrode 230 passes through the first dielectric layer 600 and contacts the first passivation layer 200, and the second electrode 320 passes through the first dielectric layer 600 and contacts the second passivation layer 300; the metal electrode includes any one or two or more of a silver electrode, a copper electrode, an aluminum electrode, a tin-clad copper electrode, and a silver-clad copper electrode.

[0122] The isolation region 400 includes a first inclined surface 410 that coincides with the cross-section of the first passivation layer 200 and a second side surface 420 that coincides with the cross-section of the second passivation layer 300. The bottom of the first inclined surface 410 and the bottom of the second side surface 420 intersect near the surface of the base silicon wafer 100 to form an intersection region 430. From the intersection region 430, the first inclined surface 410 extends outward (the outward direction is away from the back surface of the base silicon wafer 100) to the bottom of the first dielectric layer 600 (the bottom is toward the back surface of the base silicon wafer 100). The second side surface 420 extends outward to the bottom of the first dielectric layer 600. The first inclined surface 410 and the second side surface 420 form an angle of 5 to 60 degrees.

[0123] Regarding the angle of the isolation region 400, it is possible that it is the angle formed by the intersection of the extended lines of the tangent (or cut surface) of the first inclined surface 410 and the second side surface 420, as shown in Figure 21. However, it can be confirmed that the inclination of the first inclined surface 410 is greater than that of the second side surface 420. That is, as shown in Figure 22, the dotted line a is perpendicular to the surface of the base silicon wafer 100, and the angle α1 between the first inclined surface 410 and the dotted line a is greater than the angle α2 between the second side surface 420 and the dotted line a, further satisfying that the angle α1 is greater than or equal to twice the angle α2. Furthermore, the first inclined surface 410 extends outward to the point of contact with the first dielectric layer 600, and the second side surface 420 extends outward to the point of contact with the first dielectric layer 600. The vertical projection distance H between the two contact points in the direction of the base silicon wafer is 20-100 μm.

[0124] To further illustrate, the base silicon wafer 100 has a front side that faces the sun during normal operation and a back side opposite the front side. The front side is the light-receiving side, and the back side is located on the other side of the base silicon wafer 100 relative to the front side. The base silicon wafer 100 can be a P-type or N-type silicon wafer, and can be a single crystal silicon wafer or a quasi-single crystal silicon wafer. The type of base silicon wafer 100 can be selected based on actual usage requirements. Specifically, in this embodiment, the base silicon wafer 100 used is an N-type single crystal silicon wafer with a thickness of 130 μm, a resistivity of 10 ohm·cm, and a doping concentration of 4.5E14 m-3.

[0125] As shown in FIG2 , the isolation region 400 has a depth of 0 to 0.5 microns above the base silicon wafer 100. That is, the intersection 430 between the first inclined surface 410 and the first side surface 420 of the isolation region 400 does not contact the base silicon wafer 100, or the depth (position) above the base silicon wafer 100 is 0 to 0.5 microns. In some preferred embodiments of the present invention, the lowest point of the intersection 430 does not contact the base silicon wafer 100. Specifically, in this embodiment, the first inclined surface 410 and the second side surface 420 of the isolation region 400 form an angle of 45°, and the angle α1 is greater than twice the angle α2. Therefore, the isolation region 400 does not contact the base silicon wafer 100.

[0126] The first passivation layer 200 includes a bottom passivation layer 210 in direct contact with the back of the base silicon wafer 100, and a top passivation layer 220 stacked on the bottom passivation layer 210 (the bottom is the side relatively close to the back of the base silicon wafer 100, and the top is the side relatively far away from the back of the base silicon wafer 100). The bottom passivation layer 210 and the top passivation layer 220 have the same polarity, and it should be noted that the bottom passivation layer and the second passivation layer contain the same doping impurities but have opposite polarities. Specifically in this embodiment, the selected base silicon wafer 100 is an N-type single crystal silicon wafer, then the bottom passivation layer and the top passivation layer 200 are both P-type, containing P-type impurities, specifically the doping concentration of boron is 5E19cm-3. The second passivation layer is N-type, containing N-type impurities, specifically the doping concentration of phosphorus is 4E20cm-3. However, it should be noted that the bottom passivation layer also contains the same doping impurities as the second passivation layer, but the concentration is only 1E19 cm-3.

[0127] The top passivation layer 220 includes a top tunneling oxide layer 221 and a top doped polysilicon layer 222; the bottom passivation layer 210 includes a bottom tunneling oxide layer 211 and a bottom doped polysilicon layer 212; and the second passivation layer 300 includes a second tunneling oxide layer 311 and a second doped polysilicon layer 312. Specifically, in this embodiment, the first electrode 230 passes through the first dielectric layer 600 to contact the top doped polysilicon layer 222; and the second electrode 3200 passes through the first dielectric layer 600 to contact the second doped polysilicon layer 312.

[0128] The "tunneling oxide layer" is mainly an ultra-thin oxide layer, which has an important influence on the properties of the passivation contact, and good contact comes from the defect-assisted tunneling mechanism or the micropores on the oxide layer. Preferably, the ultra-thin oxide layer is an ultra-thin silicon oxide layer. Regarding the formation of the ultra-thin silicon oxide layer, there are currently mainly thermal oxidation methods (including dry oxygen oxidation and wet oxygen oxidation), chemical vapor deposition (CVD) methods (including plasma chemical vapor deposition (PECVD) methods, low-pressure chemical vapor deposition (LPCVD) methods), room temperature wet oxidation methods, etc., preferably low-pressure chemical vapor deposition (LPCVD) methods. In some preferred embodiments of the present invention, the top tunneling oxide layer 221 has a thickness of 0.5-3nm, the bottom tunneling oxide layer 211 has a thickness of 0.5-3nm, and the second tunneling oxide layer 311 has a thickness of 0.5-3nm.

[0129] There are two main methods for forming the "doped polysilicon layer": the first is to directly deposit the doped polysilicon layer using the LPCVD method. This method can complete the deposition and doping of the polysilicon film in one step; the second is to first deposit the intrinsic polysilicon film using the PECVD or LPCVD method, and then use ion implantation, diffusion and other processes to dope it. The various doping methods have similar process effects. In some preferred embodiments of the present invention, the top doped polysilicon layer 222 has a thickness of 30 to 300 nm, the bottom doped polysilicon layer 212 has a thickness of 30 to 300 nm, and the second doped polysilicon layer 312 has a thickness of 30 to 300 nm. In other preferred embodiments of the present invention, the top doped polysilicon layer 222 has a thickness of 100 to 300 Å, the bottom doped polysilicon layer 212 has a thickness of 100 to 300 Å, and the second doped polysilicon layer 312 has a thickness of 100 to 300 Å. In some other preferred embodiments of the present invention, the top doped polysilicon layer 222 has a doping capacity of 3E19 cm -3 ~10E19cm -3 The doping concentration of the bottom doped polysilicon layer 212 is 3E19cm -3 ~10E19cm -3 The doping concentration of the second doped polysilicon layer 312 is 3E20cm-3 ~10E20cm -3 doping concentration.

[0130] Specifically in this embodiment:

[0131] S1. The surface of the base silicon wafer is first polished. In this embodiment, a KOH alkaline liquid reacts with the base silicon wafer 100 to remove the surface damage layer and form a polished mirror surface. However, it should be noted that this step can actually be performed using any existing method, and the various methods have similar process effects.

[0132] S2. First, a 1.5 nm thick tunneling oxide layer is formed on the back side of the base silicon wafer 100 using LPCVD, and a 130 nm thick polysilicon layer is deposited. Then, a first doped silicon oxide layer is deposited and crystallized using a diffusion process. As shown in FIG5 , a tunneling oxide layer, a doped polysilicon layer, and a doped silicon oxide layer are sequentially formed on the surface of the base silicon wafer 100.

[0133] S3. The doped silicon oxide layer in the first region 01 is removed by patterned etching or laser etching and the doped silicon oxide layer in the second region 02 is retained, as shown in FIG6 ;

[0134] S4. Using a PECVD device, a 1 nm thick silicon oxide layer, a 170 nm thick polysilicon layer, and a second doped silicon oxide layer are first thermally oxidized and grown on the surface of the base silicon wafer 100 as shown in FIG. 6 (forming a stacked multilayer structure);

[0135] Next, the stacked multilayer structure formed in this step in the second region 02 is removed by laser. The stacked multilayer structure formed in this step in the first region 01 is retained, but it is necessary to ensure that the coverage area (length) of the second doped silicon oxide layer in the first region 01 is smaller than that of the polysilicon layer in the length direction of the base silicon wafer 100, as shown in FIG. 7 .

[0136] It should also be noted that the doping impurities in the second doped silicon oxide layer are different from the doping impurities in the first doped silicon oxide layer, and the concentration of the doping impurities in the second doped silicon oxide layer is 3E20cm-3, and the concentration of the doping impurities in the first doped silicon oxide layer is 5E19cm-3. Based on this, the concentration of the doping impurities in the second doped silicon oxide layer is significantly higher than the concentration of the doping impurities in the first doped silicon oxide layer.

[0137] Subsequently, the dopant impurities in the second doped silicon oxide layer are pushed into the underlying layer through thermal propulsion, simultaneously forming an inversion in the underlying diffusion region. Simultaneously, the dopant impurities in the first doped silicon oxide layer still present in the second region are also pushed into the underlying layer, further increasing the surface concentration and crystallization of the underlying passivation layer.

[0138] Since the concentration of the dopant impurities in the second doped silicon oxide layer is significantly higher than the concentration of the dopant impurities in the first doped silicon oxide layer, upon completion of the treatment process, the polarity of the passivation layer in the first region 01 changes to a polarity opposite to that of the passivation layer in the second region;

[0139] Furthermore, because the second doped silicon oxide layer in the first region 01 has a smaller coverage area (length) than the underlying polysilicon layer along the length of the base silicon wafer 100, after this step, the polysilicon layer region underlying the second doped silicon oxide layer is converted into a doped polysilicon region, while the polysilicon layer region not underlying the second doped silicon oxide layer remains undoped, as shown in FIG8 .

[0140] Further, the bottom passivation layer and the second passivation layer in the back contact structure of the TBC solar cell ultimately contain the same dopant impurities, but have opposite polarities. As shown in Figure 5 , the bottom passivation layer and the second passivation layer are actually formed simultaneously in step S2. Therefore, the bottom passivation layer and the second passivation layer contain the same dopant impurities. Furthermore, after completing steps S3 and S4 as shown in Figures 6-8 , the polarity of the bottom passivation layer is further altered.

[0141] S5. Use KOH alkaline solution to etch the first region 01. During this process, the lower the doping concentration of polysilicon, the faster the etching reaction rate. In particular, the non-doped polysilicon region shown in Figure 8 has the characteristic of rapid corrosion. The corrosion rate of the doped polysilicon layer located at the bottom of the first region 01 is faster than the corrosion rate of the doped polysilicon layer located in the second region. Ultimately, an isolation region with a first bevel as shown in Figure 9 can be formed. This is also the reason why the inclination degree (angle α1) of the first bevel 410 is greater than the inclination degree (angle α2) of the second side surface 420. The etching meets the following conditions: the mass fraction concentration of KOH is 1.5%, the temperature is 70°C, a texturing additive with the functional characteristics of protecting the oxide layer is selected, and the reaction time is 350s.

[0142] At this time, after S1-S5 as described above, as shown in Figure 9, a bottom passivation layer 210 and the top passivation layer 220 with the same polarity are finally formed in the first region 01 (including the bottom tunneling oxide layer 211, the bottom doped polysilicon layer 212, the top tunneling oxide layer 221, and the top doped polysilicon layer 222 stacked in sequence on the back of the base silicon wafer 100); a second passivation layer with a polarity opposite to that of the bottom passivation layer 210 is formed in the second region (including the second tunneling oxide layer 311 and the second doped polysilicon layer 312 stacked in sequence on the back of the base silicon wafer 100); and an isolation region as described above is formed between the first region 01 and the second region.

[0143] Regarding the "first dielectric layer 600", it includes an oxide layer, a silicon nitride layer (SiN x layer), and one or more combinations of an amorphous silicon layer. As some examples of the present invention, the first dielectric layer can be an oxide layer of a single material, a combination of oxide layers of multiple materials and an amorphous silicon layer, or a combination of multiple layers of amorphous silicon with different refractive indices. Furthermore, the first dielectric layer can also be a silicon oxynitride layer, a silicon nitride layer, or the like. It is understood that the specific structure of the first dielectric layer 600 includes, but is not limited to, the methods listed above. The first dielectric layer can be configured accordingly based on actual usage needs and is not specifically limited here. In some preferred embodiments of the present invention, the first dielectric layer 600 has a thickness of 3 to 90 nm and a refractive index of 1.9 to 2.1. In other preferred embodiments of the present invention, the first dielectric layer 600 is preferably an oxide layer with a thickness of 3 to 10 nm and a silicon nitride layer with a thickness of 50 to 80 nm. In this case, the oxide and silicon nitride layers are arranged outward from the base silicon wafer 100, with the oxide layer in contact with the inner passivation layer and the silicon nitride layer in contact with the oxide layer. Furthermore, the oxide layer is preferably composed of one or more layers of a silicon oxide layer (SiO2 layer) and an aluminum oxide layer (Al2O3 layer); therefore, the first dielectric layer may also be a combination of the silicon oxide layer and the aluminum oxide layer in the oxide layer. The silicon nitride layer in the first dielectric layer includes a hydrogenated silicon nitride layer.

[0144] Regarding the formation of the first dielectric layer, the SiO2 layer can be prepared by thermal oxidation (including dry oxygen oxidation, wet oxygen oxidation), chemical vapor deposition (CVD) (including plasma chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD)), room temperature wet oxidation, etc., which is prepared according to actual use needs and is not specifically limited here; the SiN xThe layer can be prepared by chemical vapor deposition (CVD) method (including plasma chemical vapor deposition (PECVD) method, low pressure chemical vapor deposition (LPCVD) method) and magnetron sputtering technology, etc., which is prepared according to actual use needs. If conditions permit, it is preferred to use chemical vapor deposition (CVD) method (including plasma chemical vapor deposition (PECVD) method, low pressure chemical vapor deposition (LPCVD) method) to prepare SiN film; the aluminum oxide layer can be prepared by atomic layer deposition (ALD) method, plasma assisted ALD method, pyrolysis deposition method, delocalized PECVD method, molecular beam epitaxy, deposition A1 plus oxidation method, etc., which is prepared according to actual use needs and is not specifically limited here. Among them, SiN x When Al2O3 and Al2O3 thin films are deposited, a large amount of hydrogen will be generated, which can form good hydrogen passivation.

[0145] Specifically in this embodiment: Step S6 is performed: a first dielectric layer 600 is deposited on the surface of the base silicon wafer using plasma atomic layer deposition (ALD) and plasma chemical vapor deposition (PECVD), as shown in FIG10 ;

[0146] The first dielectric layer 600 includes a first oxide layer 610 (aluminum oxide layer) with a thickness of 5 nm and a first silicide layer 620 (hydrogenated silicon nitride layer) with a thickness of 75 nm. Finally, the refractive index of the first dielectric layer 600 is 2.05.

[0147] Step S7 is performed: as shown in FIG11 , a first silver electrode 230 and a second silver electrode 320 are printed on the back side of the base silicon wafer 100 and sintered to form an ohmic contact.

[0148] Example 3

[0149] The third embodiment of the present invention further provides a TBC solar cell. For ease of description, only the portion related to the embodiment of the present invention is shown, as shown in FIG. 4 and FIG. 12 to FIG. 18 .

[0150] The TBC solar cell (TBC-1) shown includes: a base silicon wafer 100;

[0151] A back contact structure as described in Example 1 is provided on the back side of the base silicon wafer 100;

[0152] A second dielectric layer 500 is provided on the front surface of the base silicon wafer 100;

[0153] In principle, the composition and structure of the second dielectric layer 500 can be the same as or different from that of the first dielectric layer 600, and can be adjusted accordingly as needed. Specifically, in this embodiment, the second dielectric layer 500 is exactly the same as the first dielectric layer 600. Regarding the preparation of the TBC solar cell in this embodiment:

[0154] Step A1 is the same as step S1 in Example 1;

[0155] Step A2 is the same as step S2 in Example 1, and the structure shown in FIG12 is obtained;

[0156] Step A3: Same as step S3 of Example 1, obtaining the structure shown in FIG13 ;

[0157] Step A4: Same as step S4 in Example 1, obtaining the structure shown in FIG14 ;

[0158] Step A5: Using a single-sided film removal method, remove the hybrid structure grown on the front side of the base silicon wafer to obtain the structure shown in FIG15 ;

[0159] Step A6: Texturing the front surface of the base silicon wafer after the A5 treatment to obtain a textured structure 110 with a height of 1.2 μm as shown in FIG16 . Simultaneously, the operation described in step S5 of Example 1 is performed to obtain a back surface structure as shown in FIG16 .

[0160] Step A7: Same as step S6 of Example 1, obtaining the structure shown in FIG17 ;

[0161] Step A8: Same as step S7 of Example 1, obtaining the structure shown in FIG18;

[0162] It should be pointed out that regarding the texturing described in step A6, based on this, the reflection loss of surface light can be further reduced, the utilization rate of the base silicon wafer 100 to the incident light can be improved, thereby increasing the short-circuit current of the battery. The method of texturing can generally adopt mechanical grooving, chemical corrosion, plasma etching, etc., and finally obtain a velvet structure which includes but is not limited to alkali polishing surface, mechanical polishing surface, random pyramid shape, inverted pyramid shape, spherical crown shape, V-shaped groove shape, and morphology between the above morphologies. In addition, it can usually form an irregular hemispherical velvet texture texture during acid texturing, form a pyramid-shaped velvet texture texture during alkali texturing, or first form a pyramid-shaped velvet texture texture by alkali texturing and then smooth the pyramid spire by acid texturing. At this time, the surface morphology formed at the groove on the back side of the base silicon wafer 100 is conducive to increasing the absorption and reuse of light by the base silicon wafer 100, thereby increasing the short-circuit current density, thereby improving the conversion efficiency of the solar cell. In addition, based on the above, it is not difficult to see that the height of the velvet texture of the velvet structure 110 will also affect the reflectivity of the base silicon wafer 100. As for the "thickness of the base silicon wafer 100", it should be noted that reducing the thickness of the silicon wafer can effectively reduce the carrier recombination rate and thus obtain a higher open circuit voltage. However, since crystalline silicon has a low absorption coefficient of incident light, after reducing the thickness of the silicon wafer, the silicon wafer will absorb less sunlight, thereby causing a reduction in the short-circuit current of the battery. In summary, based on actual needs, corresponding adjustments can be made to the thickness of the base silicon wafer 100, the height of the velvet texture, the reflectivity, etc.

[0163] Example 4

[0164] This embodiment provides another TBC solar cell (TBC-2), where the difference between TBC-1 and TBC-2 lies only in the doping type of the silicon wafer.

[0165] Example 5

[0166] This embodiment also provides a TBC solar cell (TBC-3). The only difference between TBC-1 and TBC-3 is that the intersection region 430 of the isolation region 400 of TBC-3 contacts the base silicon wafer 100 and has a depth of 0.5 microns on the base silicon wafer 100.

[0167] Comparative Example 1

[0168] In addition, for comparison, two other solar cells are provided in this comparative example: TBC-D1, TBC-D2, TBC-D3, and TBC-D4;

[0169] The TBC-D1 cell structure is the same as the solar cell provided in Example 2 of the present invention, except that the “first passivation layer” only includes a “top passivation layer”.

[0170] The TBC-D2 cell structure is the same as the solar cell provided in Example 2 of the present invention, except that the "first passivation layer" only includes a "bottom passivation layer".

[0171] The TBC-D3 cell structure is the same as the solar cell provided in Example 2 of the present invention, with the only difference being that the "isolation region 400" is shown in FIG19. The overall shape of the isolation region 400 is close to a rectangle, that is, both sides are nearly perpendicular to the surface of the silicon wafer base, that is, it no longer has the first inclined surface 410 of the isolation region 400 shown in FIG3 of the present invention.

[0172] The TBC-D4 cell structure is basically the same as the solar cell TBC-D3 provided in the comparative example of the present invention, as shown in FIG20 , with the only difference being that the bottom surface of the isolation region 400 is approximately 2 microns deep in the base silicon wafer 100 as shown.

[0173] Table 1. Performance comparison parameters of various solar cells

[0174] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The back contact structure of the TBC solar cell, characterized in that, The back contact structure includes: a passivation layer provided on the back surface of the base region silicon wafer, and a dielectric layer provided on the passivation layer; The passivation layer includes a first passivation layer, a second passivation layer having a polarity opposite to that of the first passivation layer, and an isolation region located between the first passivation layer and the second passivation layer; Wherein, the isolation region includes a first inclined surface and a second side surface; the first inclined surface is formed on the first passivation layer; the second side surface is formed on the second passivation layer; the bottom of the first inclined surface intersects with the bottom of the second side surface on the surface close to the base region silicon wafer, and starting from the intersection region, the first inclined surface extends outward to contact the dielectric layer, the second side surface extends outward to contact the dielectric layer, and an angle of 5-60° is formed between the first inclined surface and the second side surface.

2. The back contact structure of the TBC solar cell according to claim 1, wherein The back contact structure further includes an electrode, and the electrode passes through the dielectric layer to contact the passivation layer.

3. The back contact structure of the TBC solar cell according to claim 2, characterized in that, The TBC solar cell can be applied to a solar cell panel. The electrode includes a first electrode and a second electrode. The first electrode passes through the dielectric layer to contact the first passivation layer, and the second electrode passes through the dielectric layer to contact the second passivation layer.

4. The back contact structure of the TBC solar cell according to claim 3, characterized in that, The passivation layer includes a tunneling oxide layer provided on the back surface of the base region silicon wafer, and a doped polysilicon layer provided on the tunneling oxide layer; The intersection region exists in the tunneling oxide layer.

5. The back contact structure of the TBC solar cell according to any one of claims 1 to 4, characterized in that, The inclination degree of the first inclined surface is greater than that of the second side surface.

6. The back contact structure of the TBC solar cell according to claim 5, characterized in that, The depth of the isolation region on the base region silicon wafer does not exceed 0.5 microns; Or, the isolation region does not form contact with the base region silicon wafer.

7. The back contact structure of the TBC solar cell according to claim 5, characterized in that, The first passivation layer includes: a bottom passivation layer provided on the back surface of the base region silicon wafer; A top passivation layer stacked on the bottom passivation layer; The bottom passivation layer and the top passivation layer have the same polarity; The first electrode passes through the dielectric layer to contact the top passivation layer.

8. The back contact structure of the TBC solar cell according to claim 7, characterized in that, The bottom passivation layer and the second passivation layer contain the same doping impurities but have opposite polarities.

9. The back contact structure of the TBC solar cell according to claim 7 or 8, characterized in that, The top passivation layer includes a tunneling oxide layer and a doped polysilicon layer; the bottom passivation layer includes a tunneling oxide layer and a doped polysilicon layer; the second passivation layer includes a tunneling oxide layer and a doped polysilicon layer; And / or, The doped polysilicon layer has a thickness of 100-300 nm; And / or, The tunneling oxide layer has a thickness of 0.5-3 nm; And / or, The doped polysilicon layer of the top passivation layer has a doping concentration of 3E19 cm -3 ~10E19 cm -3 ; And / or, The doped polysilicon layer of the bottom passivation layer has a doping concentration of 3E19 cm -3 ~10E19 cm -3 ; And / or, The doped polysilicon layer of the second passivation layer has a doping concentration of 3E20 cm -3 ~10E20 cm -3 .

10. The back contact structure of the TBC solar cell according to claim 7 or 8, characterized in that, The dielectric layer includes one or a combination of an oxide layer, a silicon nitride layer, and an amorphous silicon layer; And / or, The dielectric layer has a thickness of 3-90 nm; And / or, The dielectric layer has a refractive index of 1.9-2.

1.

11. The back contact structure of the TBC solar cell according to claim 10, characterized in that, The dielectric layer includes an oxide layer in contact with the passivation layer, and a silicon nitride layer in contact with the oxide layer; And / or, The oxide layer has a thickness of 3-10 nm; the silicon nitride layer has a thickness of 50-80 nm.

12. Preparation method of back contact structure of TBC solar cell, characterized in that, Including: Step S1: Polish the surface of the base region silicon wafer; Step S2: Deposit a bottom tunneling oxide layer, a bottom amorphous silicon layer, and a doped silicon oxide layer on the surface processed in step S1, and perform diffusion doping and crystallization by means of thermal diffusion; Step S3: Remove the doped silicon oxide layer in the first region and retain the doped silicon oxide layer in the second region; Step S4: Deposit an oxide layer, a top undoped polysilicon layer, and a doped silicon oxide layer on the surface of the first region after the treatment in Step S3; and by means of thermal propulsion, while pushing the doped impurities in the doped silicon oxide layer towards the bottom tunneling oxide layer, form an inversion of the bottom tunneling oxide layer and the bottom polysilicon layer; Synchronously, increase the surface concentration of the doped silicon oxide layer in the second region; wherein, the covered area of the doped silicon oxide layer is smaller than the covered area of the top undoped polysilicon layer; Step S5: Etch the top doped polysilicon layer deposited on the surface of the first region to form an isolation region with a first inclined surface; Step S6: Deposit an oxide and a hydrogenated silicon nitride layer on the surface of the base region silicon wafer; Step S7: Print the first and second electrodes and sinter to form ohmic contacts.

13. TBC solar cell, characterized in that, Comprising: A base region silicon wafer; A back contact structure provided on the back surface of the base region silicon wafer, the back contact structure being as described in any one of claims 1 to 11 or prepared by the method as described in claim 12; a second dielectric layer provided on the front surface of the base region silicon wafer; And / or, The second dielectric layer comprises one or more combinations of an oxide layer, a silicon nitride layer, and an amorphous silicon layer; And / or, The second dielectric layer comprises an oxide layer and a silicon nitride layer, wherein the second dielectric layer has a thickness of 3 to 90 nm.

14. Preparation method of a TBC solar cell, characterized in that, Comprising: Step A1: Polish the surface of the base region silicon wafer; Step A2: Deposit a bottom tunneling oxide layer, a bottom amorphous silicon layer, and a doped silicon oxide layer on the surface after the treatment in Step A1, and perform diffusion doping and crystallization by means of thermal diffusion; Step A3: Remove the doped silicon oxide layer in the first region and retain the doped silicon oxide layer in the second region; Step A4: Deposit an oxide layer, a top undoped polysilicon layer, and a doped silicon oxide layer on the surface of the first region after the treatment in Step A3; and by means of thermal propulsion, while pushing the doped impurities in the doped silicon oxide layer towards the bottom tunneling oxide layer, form an inversion of the bottom tunneling oxide layer and the bottom polysilicon layer; Synchronously, increase the surface concentration of the doped silicon oxide layer in the second region; wherein, the covered area of the doped silicon oxide layer is smaller than the covered area of the top undoped polysilicon layer; Step A5: Use a single-sided film removal method to remove the hybrid structure grown on the front surface of the base region silicon wafer; Step A6: Texture the front surface of the base region silicon wafer after the treatment in Step A5; simultaneously, etch the top doped polysilicon layer deposited on the surface of the first region to form an isolation region with a first inclined surface; Step A7: Deposit an oxide and a hydrogenated silicon nitride layer on the surface of the base region silicon wafer; Step A8: Print the first and second electrodes on the back surface of the base region silicon wafer and sinter to form ohmic contacts.

15. A photovoltaic module, characterized in that, The photovoltaic module includes a solar panel and a photovoltaic module bracket for supporting the solar panel; the photovoltaic module bracket includes: a frame for fixing the solar panel; a central pillar connected to the frame through a universal rotary joint; a first support rod assembly including a connecting rod and a rotating rod, one end of the connecting rod is connected to the central pillar and can rotate in a plane Y parallel to the length direction of the central pillar, the other end of the connecting rod is hinged to one end of the rotating rod, and the other end of the rotating rod is connected to the frame through an annular guide rail slider assembly with a positioning function; a second support rod assembly including a support rod, one end of the support rod is connected to the central pillar and can rotate in a plane X perpendicular to the plane Y, and one end of the support rod is hinged to the frame; The solar panel includes solar cells, which are as described in claim 13 or prepared by the method described in claim 14; And / or, the annular guide rail slider assembly with a positioning function includes a slider and an annular guide rail; the annular guide rail forms a loop centered on the connection between the central pillar and the frame; the rotating rod is hinged to the slider.

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