Photovoltaic back glass, preparation method and photovoltaic module

Abstract

The invention relates to photovoltaic back glass, a preparation method and a photovoltaic module. The photovoltaic back glass comprises a glass body and a functional film comprising an outer layer film and a composite film, wherein the outer layer film, the composite film and the glass body are sequentially arranged, and the outer layer film is a TiO2 film layer; the composite film comprises a first film layer and a second film layer, the first film layer and the second film layer are staggered, stacked and circulated for multiple times, the first film layer on the topmost layer is arranged on one side of the outer layer film, the first film layer is a SiO2 film layer, the second film layer on the bottommost layer is further arranged on the glass body, and the second film layer is a TiO2 film layer. Through the arrangement, the functional film comprises the SiO2 film layers and the TiO2 film layers which are staggered and laminated for multiple times, and by utilizing the high light transmittance of the SiO2 film layers and the high reflectivity of the TiO2 film layers, the light transmittance of reverse light rays is improved and the reflectivity of the reverse light rays is reduced while the light reflectivity of the front light rays is increased and reduced, so that the light loss is reduced, and the light utilization rate is increased; and the outer layer film is a TiO2 film layer, so that the self-cleaning effect is improved, ultraviolet rays can be strongly absorbed, and UV attenuation is reduced.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic cell technology, and in particular to a photovoltaic back glass, a preparation method and a photovoltaic module. Background Art

[0002] As green and environmentally friendly energy is gaining more and more attention, photovoltaic energy, as an environmentally friendly energy, is gradually becoming popular among the public by using semiconductor materials to convert light energy into electrical energy. Among them, double-sided glass solar cells have the advantages of back-side power generation and low power attenuation and are widely used.

[0003] The current double-sided glass solar cell includes a cover glass, a battery assembly and a back glass arranged in sequence. During operation, the first light source emitted from the front side passes through the cover glass and reaches the effective area of ​​the battery assembly for energy conversion, and the second light emitted from the back side passes through the back glass and reaches the effective area of ​​the battery assembly for energy conversion. However, in the above process, there is a possibility that the first light source does not react with the effective area of ​​the battery assembly and directly penetrates from the back glass, and there is a possibility that the second light fails to penetrate the back glass assembly and is reflected out of the effective area of ​​the battery assembly, resulting in light loss and reduced light utilization. Summary of the invention

[0004] Based on this, it is necessary to provide a photovoltaic back glass, a preparation method and a photovoltaic module to address the problem that the current back glass is prone to cause light loss and reduce the utilization rate of light when in use.

[0005] A photovoltaic back glass, the photovoltaic back glass comprises a glass body and a functional film, the functional film comprises an outer film and a composite film, wherein:

[0006] The outer film, the composite film and the glass body are arranged in sequence, and the outer film is a TiO2 film layer;

[0007] The composite film includes a first film layer and a second film layer, the first film layer and the second film layer are alternately stacked for multiple cycles, the topmost first film layer is arranged on one side of the outer film, the first film layer is a SiO2 film layer, and the bottommost second film layer is also arranged on the glass body, the second film layer is a TiO2 film layer.

[0008] In one embodiment, the number of cycles of alternating and stacking the first film layer and the second film layer is 2 times.

[0009] In one embodiment, the thickness of the functional film is in the range of 180nm-270nm.

[0010] In one embodiment, the thickness of the outer layer is in the range of 5nm-15nm.

[0011] In one embodiment, the photovoltaic back glass further comprises a base film, the base film is disposed between the composite film and the glass body, and the base film is a SiO2 film layer;

[0012] The composite film also includes a third film layer, and the first film layer, the third film layer and the second film layer are stacked in sequence, the first film layer is one of a SiO2 film layer or an Al film layer, the third film layer is one of a SiO2 film layer, an Al film layer or a TiO2 film layer, the second film layer is one of an Al film layer or a TiO2 film layer, and the first film layer, the second film layer and the third film layer are of different film types.

[0013] In one embodiment, the thickness of the functional film is in the range of 361 nm to 426 nm.

[0014] In one embodiment, the thickness of the outer layer is in the range of 90nm-105nm.

[0015] In one embodiment, when the second film layer is an Al film layer, the thickness of the second film layer is in the range of 60nm-72nm.

[0016] The above-mentioned photovoltaic back glass is achieved by arranging a functional film on the glass body, the functional film includes SiO2 film layers and TiO2 film layers that are staggered and stacked multiple times, and utilizing the high light transmittance of the SiO2 film layer and the high reflectivity of the TiO2 film layer to increase the reflectivity of the front light and reduce the transmittance of the front light while increasing the transmittance of the back light and reducing the reflectivity of the back light, thereby reducing light loss and enhancing light utilization; and by arranging the outer layer of the functional film as a TiO2 film layer, the TiO2 film layer will enhance the self-cleaning effect on the one hand, and on the other hand, the TiO2 film layer has a strong ultraviolet absorption function, thereby reducing the UV attenuation of the photovoltaic module.

[0017] The present application also provides a method for preparing photovoltaic back glass, comprising the following steps:

[0018] Provide glass body, TiO2 sol and SiO2 sol;

[0019] coating the TiO2 sol on the glass body, and forming a second film layer after the TiO2 sol solidifies;

[0020] The SiO2 sol is coated on the side of the second film layer away from the glass body, and the first film layer is formed after the SiO2 sol solidifies, and the second film layer and the first film layer are alternately prepared in multiple layers to obtain the composite film;

[0021] The TiO2 sol is coated on the outside of the composite film, and the TiO2 sol is solidified to form an outer film, so as to complete the preparation of the photovoltaic back glass.

[0022] The present application also provides a photovoltaic module, which includes a cover glass, a first adhesive film, a battery group, a second adhesive film and the photovoltaic back glass as described in any of the above embodiments, which are stacked in sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic diagram of the structure of a photovoltaic back glass provided in the present application.

[0024] FIG2 is a schematic diagram of the structure of another photovoltaic back glass provided in the present application.

[0025] FIG3 is a flowchart of a method for preparing photovoltaic back glass provided in the present application.

[0026] in:

[0027] 10. Photovoltaic back glass;

[0028] 100. Glass body;

[0029] 200, functional film; 210, outer film; 220, composite film; 221, first film layer; 222, second film layer; 223, third film layer; 230, base film. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0031] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0032] In addition, if the terms "first" or "second" appear, these terms 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, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; 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, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0034] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0035] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0036] Refer to FIG. 1 , which is a schematic diagram of the structure of a photovoltaic back glass 10 provided in an embodiment of the present application. The photovoltaic back glass 10 provided in an embodiment of the present application includes a glass body 100 and a functional film 200, wherein the functional film 200 includes an outer film 210 and a composite film 220, wherein the outer film 210, the composite film 220 and the glass body 100 are arranged in sequence, and the outer film 210 is a TiO2 film layer. The composite film 220 includes a first film layer 221 and a second film layer 222, wherein the first film layer 221 and the second film layer 222 are alternately stacked and cyclically repeated for multiple times, wherein the topmost first film layer 221 is arranged on one side of the outer film 210, wherein the first film layer 221 is a SiO2 film layer, and the bottommost second film layer 222 is also arranged on the glass body 100, wherein the second film layer 222 is a TiO2 film layer.

[0037] The above-mentioned photovoltaic back glass 10, by setting a functional film 200 on the glass body 100, the functional film 200 includes SiO2 film layers and TiO2 film layers that are staggered and stacked multiple times, and utilizing the high light transmittance of the SiO2 film layer and the high reflectivity of the TiO2 film layer, realizes increasing the reflectivity of the front light and reducing the transmittance of the front light while increasing the transmittance of the back light and reducing the reflectivity of the back light, thereby reducing light loss and enhancing light utilization; and by setting the outer film 210 in the functional film 200 as a TiO2 film layer, the TiO2 film layer will enhance the self-cleaning effect on the one hand, and on the other hand, the TiO2 film layer has a strong ultraviolet absorption function, thereby reducing the UV attenuation of the photovoltaic module.

[0038] It should be emphasized that the functional film 200 of the present application is configured as a staggered stack of TiO2 film layers and SiO2 film layers to achieve the effect of increasing reflection and reducing transmittance of front light and increasing transmittance and reducing reflection of back light, thereby improving light utilization. However, too many film layers will cause the functional film 200 to become thicker, thereby increasing production costs and reducing production efficiency.

[0039] Based on this, in order to ensure the effect of improving the utilization rate of light while reducing the production cost, in a preferred embodiment, the number of cycles of the interlaced stacking of the first film layer 221 and the second film layer 222 in the composite film 220 is preferably 2 times. Through the above-mentioned setting, the composite film 220 includes the second film layer 222, the middle first film layer 221, the middle second film layer 222 and the top first film layer 221 arranged in sequence on the bottom layer of the glass body 100. In order for the above-mentioned film layers to cooperate with each other at a lower thickness to ensure the utilization rate of light, according to the experiment of the applicant, in the specific setting, the thickness range of the second film layer 222 of the bottom layer is 10nm-25nm, which can be any value of 12nm, 13.9nm, 15nm, 17.8nm and 10nm-25nm. The thickness range of the first film layer 221 in the middle is 20nm-30nm, which can be any value of 22nm, 24nm, 25nm, 28nm and 20nm-30nm. The thickness of the middle second film layer 222 is in the range of 100nm-130nm, and can be any value among 110nm, 114nm, 120nm, 125nm and 100nm-130nm. The thickness of the top first film layer 221 is in the range of 45nm-70nm, and can be any value among 47nm, 49nm, 60nm, 65nm and 45nm-70nm.

[0040] Similarly, in order for the outer film 210 to achieve a self-cleaning effect and reduce the UV attenuation of photovoltaic modules with a smaller thickness. In a preferred embodiment, the thickness of the outer film 210 ranges from 5nm to 15nm. In a specific setting, the thickness of the outer film 210 can be any value among 8nm, 10nm, 12nm, 14.5nm and 4nm-15nm. Through the above setting, on the one hand, the reflectivity fluctuation range of the overall functional film 200 is increased to 5%-10%; on the other hand, the thickness range of the overall functional film 200 is controlled between 180nm-270nm, so that the reflectivity of the overall functional film 200 in the visible light band can reach about 98%.

[0041] It should be noted that metal Al has a large extinction coefficient. When light enters the interior of metal Al, the light amplitude will decay rapidly, the corresponding light energy will weaken, and the reflection of light energy will increase. However, metal Al is easily oxidized in the air, and the reflectivity of metal Al cannot meet the requirements of reducing the light transmission from the front.

[0042] Based on this, refer to FIG. 2, which is a schematic diagram of the structure of another photovoltaic back glass 10 provided in an embodiment of the present application. In this embodiment, the photovoltaic back glass 10 also includes a base film 230, which is disposed between the composite film 220 and the glass body 100, and the base film 230 is a SiO2 film layer. The composite film 220 also includes a third film layer 223, and the first film layer 221, the third film layer 223 and the second film layer 222 are stacked in sequence, the first film layer 221 is one of a SiO2 film layer or an Al film layer, the third film layer 223 is one of a SiO2 film layer, an Al film layer or a TiO2 film layer, and the second film layer 222 is one of an Al film layer or a TiO2 film layer, and the film types of the first film layer 221, the second film layer 222 and the third film layer 223 are different from each other.

[0043] Through the above arrangement, the Al film layer is located between the TiO2 film layer and the SiO2 film layer. On the one hand, the Al film layer is prevented from being oxidized, and on the other hand, the purpose of increasing the reflectivity is achieved, and a high reflectivity of 95%-96% can be basically achieved in the visible light band. The interaction between the Al film layer, the TiO2 film layer and the SiO2 film layer enables the overall functional film 200 to increase the reflectivity of the front light and reduce the transmittance of the front light while increasing the transmittance of the back light and reducing the reflectivity of the back light, thereby reducing the loss of light and enhancing the utilization of light.

[0044] In the specific setting, the present application prefers that the first film layer 221 in the composite film 220 is a SiO2 film layer, the third film layer 223 is a TiO2 film layer and the second film layer 222 is an Al film layer. Through the above setting, the SiO2 film layer has a high refractive index, and the light can be repeatedly refracted in the film layer, reducing reflection and scattering, and increasing transmittance and photoelectric conversion efficiency.

[0045] The TiO2 film is a high refractive index material. It is very easy to decompose when heated and evaporated by an electron gun, and the low-valent oxides can increase absorption. However, when the TiO2 film is in a high temperature and high oxygen environment, the absorption will be reduced. The film is firm, stable, visible and transparent. The Al film can weaken the light energy and increase the reflection of the light energy. In order to prevent the oxidation of the Al film and enhance the reflectivity of the Al film, a SiO2 base film 230 is set in the composite film 220.

[0046] It should be emphasized that in the embodiment shown in FIG. 2 , the functional film 200 is also designed as a multi-layer structure, which makes the thickness of the functional film 200 thicker. On the one hand, it leads to increased production costs, and on the other hand, it leads to increased cumulative errors, increased monitoring errors, and increased stress, resulting in difficulty in demolding.

[0047] Based on this, in order to reduce production costs, production errors and production difficulties while ensuring the effect of improving light utilization, a preferred embodiment is that the thickness of the functional film 200 ranges from 361nm to 426nm. In order to reasonably allocate the thickness of each film layer to achieve mutual cooperation to ensure light utilization, in the specific setting, the thickness of the outer film 210 in the functional film 200 ranges from 90nm to 105nm, the outer film 210 is a TiO2 film layer, and the specific thickness of the outer film 210 can be any value from 94nm, 98nm, 100nm, 104nm and 90nm-105nm. The thickness of the base film 230 in the functional film 200 ranges from 75nm to 83nm, the base film 230 is a SiO2 film layer, and the specific thickness of the base film 230 can be any value from 76nm, 78nm, 80nm, 82nm and 75nm-83nm.

[0048] When the first film layer 221 of the composite film 220 in the functional film 200 is preferably a SiO2 film layer, the third film layer 223 is a TiO2 film layer, and the second film layer 222 is an Al film layer, the thickness of the first film layer 221 is in the range of 83nm-97nm, and can be any value among 85nm, 89nm, 90nm, 95nm, and 83nm-97nm. The thickness of the third film layer 223 is in the range of 53nm-69nm, and can be any value among 55nm, 58nm, 62.7nm, 65nm, and 53nm-69nm. The thickness of the second film layer 222 is in the range of 60nm-72nm, and can be any value among 64nm, 67nm, 70nm, 71.8nm, and 60nm-72nm.

[0049] Refer to FIG. 3 , which is a flowchart of a method for preparing a photovoltaic back glass 10 provided in an embodiment of the present application. The method for preparing a photovoltaic back glass 10 provided in an embodiment of the present application comprises the following steps:

[0050] Step S1, providing a glass body 100, TiO2 sol and SiO2 sol. It should be noted that both TiO2 sol and SiO2 sol are prepared by a sol-gel method and are mature technical means, which will not be elaborated in detail here;

[0051] Step S2, coating the glass body 100 with TiO2 sol, and forming the second film layer 222 after the TiO2 sol solidifies. In a specific setting, the second film layer 222 is solidified in the following manner: drying the glass body 100 coated with the TiO2 sol in an oven, the drying temperature is preferably 60 degrees Celsius, and the drying time is preferably 1 hour;

[0052] Step S3, coating SiO2 sol on the side of the second film layer 222 away from the glass body 100, and forming the first film layer 221 after the SiO2 sol solidifies, and the second film layer 222 and the first film layer 221 are prepared in multiple layers in a staggered manner according to a preset thickness to obtain the composite film 220. In the specific setting, the solidification method of the first film layer 221 is similar to that of the second film layer 222, which will not be elaborated here;

[0053] Step S4, coating the outer side of the composite film 220 with TiO2 sol, and forming the outer film 210 after the TiO2 sol solidifies, so as to complete the preparation of the photovoltaic back glass 10. In the specific setting, the solidification method of the outer film 210 is similar to the aforementioned second film layer 222. It should be noted that after the photovoltaic back glass 10 is prepared, it is necessary to further solidify the film layers on the glass body 100, specifically, the photovoltaic back glass 10 is solidified in an oven, preferably at 60 degrees Celsius for 24 hours.

[0054] The method for preparing the above-mentioned photovoltaic back glass 10 prepares a composite film 220 on the glass body 100, and the composite film 220 includes SiO2 film layers and TiO2 film layers that are staggered and stacked multiple times. The high light transmittance of the SiO2 film layer and the high reflectivity of the TiO2 film layer are utilized to increase the reflectivity of the front light and reduce the transmittance of the front light while increasing the transmittance of the back light and reducing the reflectivity of the back light, thereby reducing light loss and enhancing light utilization; an outer layer film 210 of the TiO2 film layer is also prepared. On the one hand, the TiO2 film layer will enhance the self-cleaning effect, and on the other hand, the TiO2 film layer has a strong ultraviolet absorption function, thereby reducing the UV attenuation of the photovoltaic module.

[0055] It should be noted that when preparing the photovoltaic back glass 10 as shown in Figure 2, Al sol is also required to be provided. Specifically, the corresponding sol is coated on the glass body 100 from bottom to top in the structural order shown in Figure 2, and after each layer of sol is solidified, the next layer of sol is coated. The solidification method of the sol is similar to that in the previous embodiment, and will not be elaborated here.

[0056] It should be emphasized that when preparing the photovoltaic back glass 10 described in any embodiment of the present application, before applying the sol, it is necessary to wipe the glass body 100 to remove oil and impurities on the surface of the glass body 100. The present application preferably uses a mixed solution of ethanol and ether to wipe the glass. And after step S4, it is also necessary to heat the photovoltaic back glass 10 at 100°C-300°C in a vacuum range of 1*10-2 pa -2*10-2pa through step S5, and the heating time is preferably 0.5h-1.5h, and oxygen is added at the same time to make each film layer better bonded in a clean environment. After that, the photovoltaic back glass 10 is naturally cooled to obtain the desired photovoltaic back glass 10.

[0057] Through the above settings, the present application uses the sol-gel method to prepare various film layers on the glass body 100 to obtain the photovoltaic back glass 10, that is, through different thicknesses and types of film layers to maximize the photovoltaic back glass 10 to increase reflection and reduce light transmittance for the front light and to increase light transmittance and reduce reflection for the back light. It should be emphasized that the preparation method of the photovoltaic back glass 10 of the present application is described by taking the sol-gel method as an example but is not limited to the above method, and can also be prepared by vacuum coating, gas phase or liquid phase deposition method.

[0058] The present application also provides a photovoltaic module, which includes a cover glass, a first adhesive film, a battery pack, a second adhesive film and a photovoltaic back glass 10 as described in any of the above embodiments. In specific use, the cover glass and the photovoltaic back glass 10 are both glasses facing the light source and used to transmit sunlight.

[0059] The above-mentioned photovoltaic module is provided with a photovoltaic back glass 10, and the photovoltaic back glass 10 includes a functional film 200. The functional film 200 includes SiO2 film layers and TiO2 film layers that are staggered and stacked multiple times. The high light transmittance of the SiO2 film layer and the high reflectivity of the TiO2 film layer are utilized to increase the reflectivity of the front light and reduce the transmittance of the front light while increasing the transmittance of the back light and reducing the reflectivity of the back light, thereby reducing light loss and enhancing light utilization. In addition, by setting the outer film 210 in the functional film 200 as a TiO2 film layer, the TiO2 film layer will enhance the self-cleaning effect on the one hand, and on the other hand, the TiO2 film layer has a strong ultraviolet absorption function, thereby reducing the UV attenuation of the photovoltaic module.

[0060] In specific settings, the materials of the first adhesive film and the second adhesive film in the photovoltaic module can be the same or different. For example, the materials of the first adhesive film and the second adhesive film can be one of materials such as ethylene-vinyl acetate copolymer (Ethylene-Vinyl AcetateCopolymer EVA), polyolefin elastomer (Polyolefin Elastomer POE), polyvinyl butyral PVB, etc., and can also be EPE adhesive film (EVA-POE-EVA co-extruded structure) or EP adhesive film (EVA-POE co-extruded structure). In specific use, the first adhesive film and the second adhesive film are used to encapsulate the battery pack to prevent the external environment from affecting the performance of the battery pack, and at the same time, the cover glass and the photovoltaic back glass 10 can be bonded into a whole.

[0061] In the specific configuration, the battery group in the photovoltaic module includes a plurality of battery strings connected in series or in parallel, and the battery string is formed by a plurality of battery cells connected in series, and adjacent battery cells are connected by welding strips. This embodiment does not limit the structure of the battery cells, and the types of battery cells include but are not limited to Passivated Emitter Rear Cell (PERC), Tunnel Oxide Passivated Contact (TOPCon), Heterojunction with Intrinsic Thin-film (HJT), Interdigitated Back Contact (IBC), Perovskite battery, etc.

[0062] For PERC cells, along the thickness direction, PERC cells include front surface metal silver electrode, front surface silicon nitride passivation layer, phosphorus layer emitter, P-type base silicon layer, local aluminum back field, metal aluminum back electrode, back passivation layer (Al2O3 / SiNx). PERC cells use a passivation film to passivate the back, replacing the full aluminum back field, enhancing the internal back reflection of light in the silicon base, reducing the recombination rate on the back, and increasing the efficiency of the cell by 0.5%-1%.

[0063] For TOPCon cells, along the thickness direction, TOPCon cells include metal silver electrodes, front surface silicon nitride passivation layers, boron-doped emitters, N-type base silicon layers, diffused doping layers, ultra-thin silicon oxide, doped polysilicon, silicon nitride, and metal silver electrodes. The back of the cell is composed of a layer of ultra-thin silicon oxide (1nm to 2nm) and a layer of phosphorus-doped microcrystalline amorphous mixed Si film, which together form a passivation contact structure. This structure can block the recombination of minority carrier holes and increase the open circuit voltage and short circuit current of the cell. The ultra-thin oxide layer allows majority electrons to tunnel into the polysilicon layer while blocking the recombination of minority carrier holes. The good passivation effect of ultra-thin silicon oxide and heavily doped silicon film causes the energy band on the silicon wafer surface to bend, thereby forming a field passivation effect, greatly increasing the probability of electron tunneling, reducing contact resistance, and increasing the open circuit voltage and short circuit current of the cell, thereby improving the cell conversion efficiency.

[0064] For HJT cells, along the thickness direction, the HJT cells include a front low-temperature silver electrode, a front conductive film, an N-type amorphous silicon film, an intrinsic amorphous silicon film, an N-type base silicon layer, an intrinsic amorphous silicon film, a P-type amorphous silicon film, a back conductive film, and a back low-temperature silver electrode.

[0065] For IBC cells, along the thickness direction, IBC cells include silicon nitride anti-layer, N+ front surface field, N-type base silicon layer, P+ emitter, N+ back field, aluminum oxide passivation layer, silicon nitride anti-reflection layer, and metal silver electrode. IBC cells use ion implantation technology to obtain P and N regions with good uniformity and precisely controllable junction depth. There is no grid line blocking on the front of the cell, which can eliminate the shading current loss of the metal electrode and achieve the maximum utilization of incident photons. The short-circuit current can be increased by about 7% compared with conventional solar cells; due to the back contact structure, there is no need to consider the grid line blocking problem, and the grid line ratio can be appropriately widened, thereby reducing the series resistance and having a high fill factor; the surface passivation and surface light trapping structure can be optimized to obtain a lower front surface recombination rate and surface reflection.

[0066] For perovskite cells, along the thickness direction, the perovskite cell includes substrate material, conductive film, electron transport layer (titanium dioxide), perovskite absorption layer (hole transport layer), and metal cathode. Perovskite materials have a high light absorption coefficient and a long carrier diffusion distance. After the photons absorbed by the perovskite material are converted into electrons, they are easily collected by the electrode with low loss, so they can generate higher photoelectric voltage and current, making perovskite show higher photoelectric conversion efficiency.

[0067] The battery cell can adopt a multi-busbar solution, which can shorten the current conduction path, reduce internal losses and thus increase the power of the photovoltaic module, while also reducing the cost of the photovoltaic module; it can also adopt a busbar-free solution, replacing the original busbar with a welding ribbon and directly connecting it to the fine grid, which can greatly reduce the silver paste consumption and thus reduce the cost of the photovoltaic module.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A photovoltaic back glass, characterized in that: The photovoltaic back glass comprises a glass body and a functional film, wherein the functional film comprises an outer film and a composite film, wherein: The outer film, the composite film and the glass body are arranged in sequence, and the outer film is a TiO2 film layer; The composite film includes a first film layer and a second film layer, the first film layer and the second film layer are alternately stacked for multiple cycles, the topmost first film layer is arranged on one side of the outer film, the first film layer is a SiO2 film layer, and the bottommost second film layer is also arranged on the glass body, the second film layer is a TiO2 film layer.

2. The photovoltaic back glass according to claim 1, characterized in that: The number of cycles of alternating and stacking the first film layer and the second film layer is 2 times.

3. The photovoltaic back glass according to claim 1, characterized in that: The thickness of the functional film is in the range of 180nm-270nm.

4. The photovoltaic back glass according to claim 1, characterized in that: The thickness of the outer layer film is in the range of 5nm-15nm.

5. The photovoltaic back glass according to claim 1, characterized in that: The photovoltaic back glass further comprises a base film, which is arranged between the composite film and the glass body, and is a SiO2 film layer; The composite film also includes a third film layer, and the first film layer, the third film layer and the second film layer are stacked in sequence, the first film layer is one of a SiO2 film layer or an Al film layer, the third film layer is one of a SiO2 film layer, an Al film layer or a TiO2 film layer, the second film layer is one of an Al film layer or a TiO2 film layer, and the first film layer, the second film layer and the third film layer are of different film types.

6. The photovoltaic back glass according to claim 5, characterized in that: The thickness of the functional film ranges from 361 nm to 426 nm.

7. The photovoltaic back glass according to claim 4, characterized in that: The thickness of the outer layer film is in the range of 90nm-105nm.

8. The photovoltaic back glass according to claim 4, characterized in that: When the second film layer is an Al film layer, the thickness of the second film layer is in the range of 60nm-72nm.

9. A method for preparing photovoltaic back glass according to claim 1, characterized in that: The steps include: Provide glass body, TiO2 sol and SiO2 sol; coating the TiO2 sol on the glass body, and forming a second film layer after the TiO2 sol solidifies; The SiO2 sol is coated on the side of the second film layer away from the glass body, and the first film layer is formed after the SiO2 sol solidifies, and the second film layer and the first film layer are alternately prepared in multiple layers to obtain the composite film; The TiO2 sol is coated on the outside of the composite film, and the TiO2 sol is solidified to form an outer film, so as to complete the preparation of the photovoltaic back glass.

10. A photovoltaic module, characterized in that: The photovoltaic module comprises a cover glass, a first adhesive film, a battery group, a second adhesive film and the photovoltaic back glass according to any one of claims 1 to 8 which are stacked in sequence.

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