Solar frequency division PV / T system coupled with micro-nano film and cavity type heat collector

Abstract

The invention provides a solar frequency division PV / T system coupled with a micro-nano film and a cavity type heat collector. The solar frequency division PV / T system comprises a linear Fresnel lens and the cavity type solar heat collector. A lighting window is formed in the heat collector in the axis direction, a micro-nano frequency division film is arranged on the inner wall face, right facing the lighting window, of a heat absorption cavity, and a concentrating photovoltaic cell is arranged below the micro-nano frequency division film. Sunlight is concentrated to the lighting window through the linear Fresnel lens at the top, is secondarily reflected by the lighting window to be collected to the cylindrical heat absorption cavity of the heat collector and irradiates the micro-nano film at the bottom, the micro-nano film transmits available wave bands in solar spectrum to the photovoltaic cell for power generation, light of other wave bands is reflected to the inner wall face of the heat absorption cavity, and the light of the other wave bands is reflected to the inner wall face of the heat absorption cavity. The heat is absorbed by the heat absorption coating, converted into heat energy and transmitted to the working medium layer, so that gradient utilization of the full spectrum of the sun is realized. The cavity type heat collector structure can effectively reduce energy dissipation caused by radiation and convective heat transfer, and the solar energy utilization efficiency of the system is improved.

Description

Technical Field

[0001] The present invention relates to the field of solar energy technology, and in particular to a solar frequency-divided PV / T system (photovoltaic / thermal energy system) coupling a micro-nano film and a cavity collector. Background Art

[0002] With the promotion of clean energy utilization, solar energy as a clean and renewable energy has attracted much attention. At present, there are two main ways to utilize solar energy: photovoltaic power generation and photothermal utilization. However, these two separate utilization methods have the following disadvantages: for photovoltaic power generation, solar cell materials can only use the visible light band in the solar spectrum to convert into electrical energy, and the remaining bands cannot be used, resulting in nearly 40% energy waste, which becomes waste heat and causes the battery temperature to rise and the efficiency to decrease; for photothermal utilization, it converts the entire spectrum of sunlight into low-grade thermal energy, resulting in irreversible energy loss of high-grade light energy. Therefore, frequency division and utilization of solar energy is an important way to improve the efficiency of solar energy utilization, that is, to use high-grade energy in solar energy for photovoltaic power generation and low-grade energy for photothermal utilization, coupling the two utilization methods, and realizing the cascade utilization of solar energy. However, there are several problems in the current solar energy frequency division and utilization technology, including the high temperature resistance of the divider material, the spectrum matching problem between the divider and the photovoltaic cell, and the processing cost problem of the divider.

[0003] The linear collector is the core component of the linear focusing solar thermal power generation technology. It is usually a metal high-temperature collector tube, and generally uses two types of vacuum collectors and cavity collectors. The vacuum collector is composed of a metal heat-absorbing tube with a selective absorption coating, a concentric glass tube jacket, and a metal-glass sealed connection. The vacuum collector absorbs radiation and heats the working fluid flowing inside by the metal heat-absorbing tube in the middle. The vacuum environment in the glass tube avoids heat dissipation caused by convective heat transfer. When the vacuum collector is used for linear focusing solar thermal power generation, it is equipped with a short-focal-length parabolic concentrator, which has a low center of gravity and good operating stability. However, the sealing technology between the glass tube and the metal tube requires high requirements, and it is difficult to maintain a high vacuum degree in the interlayer for a long time. The cavity collector has a heat-absorbing coating applied to the inner wall. When the light is reflected twice by the light-collecting window and collected in the cylindrical heat-absorbing cavity of the collector, it is reflected at the bottom and reflected multiple times by the inner wall before being absorbed by the heat-absorbing coating on the inner wall, converted into heat energy and transferred to the working fluid layer on the outer wall of the cavity to heat the flowing working fluid. The outermost thermal insulation layer can effectively reduce the energy dissipation caused by radiation and convection heat transfer. The cavity collector does not need to maintain the strict requirement of vacuum, and the structure avoids the difficulty of sealing glass tubes and metal tubes. The structure is simpler, but when used for linear focusing solar thermal power generation, it is equipped with a long-focal-length parabolic concentrator. The center of gravity of the collector tube is high, the operating stability is relatively poor, it is difficult to automatically flip, and the wind resistance is poor. Summary of the invention

[0004] In view of the above existing solar energy utilization problems, the present invention designs a solar frequency division PV / T system that couples micro-nano film and cavity collector, uses a new cavity structure to achieve efficient capture of light and heat, and integrates coupled frequency division elements to use high-grade solar energy for photovoltaics and low-grade energy for photothermal energy, coupling the two utilization methods to achieve tiered and efficient utilization of solar energy.

[0005] The technical solution adopted by the present invention is: a solar frequency division PV / T system coupling a micro-nano film and a cavity collector, which includes a linear Fresnel lens and a cavity solar collector; wherein the cavity solar collector includes, from the inside to the outside, a cylindrical heat absorption cavity, a working fluid layer wrapped in the outer layer of the heat absorption cavity, and a heat preservation and insulation layer wrapped in the working fluid layer; the cavity solar collector is provided with a lighting window on the side wall along the axial direction, and a micro-nano frequency division film is provided on the inner wall surface of the heat absorption cavity facing the lighting window, a concentrating photovoltaic cell is provided below the micro-nano frequency division film, a vacuum cavity is provided between the micro-nano frequency division film and the concentrating photovoltaic cell, and a reflective material is provided on the wall surface of the vacuum cavity;

[0006] The cavity solar collector is arranged directly below the symmetrical central axis of the linear Fresnel lens, and the lighting window faces the linear Fresnel lens. The linear Fresnel lens focuses the incident solar radiation to the lighting window, and irradiates the micro-nano frequency division film in the heat absorption cavity through the lighting window.

[0007] Furthermore, the linear Fresnel lens and the cavity solar collector are fixedly connected to maintain the relative position between the two; the system also includes a support frame system, which is used to adjust the rotation angle of the solar frequency division PV / T system so that the solar radiation is vertically incident on the linear Fresnel lens.

[0008] According to an embodiment of the present invention, the micro-nano film is TiO 2 and SiO 2 The optical interference multilayer frequency-dividing film is made of two materials alternately deposited on a transparent substrate. The interference effect caused by light alternately passing through thin film layers with large differences in refractive index is used to achieve the selective transmission effect of the solar spectrum. The photovoltaic cell can use part of the band (wavelength of 400nm~900nm) to transmit to the photovoltaic cell below to generate electricity, and the remaining band is reflected to the inner wall of the surrounding heat absorption cavity.

[0009] According to a preferred embodiment of the present invention, the lighting window is composed of a rectangular channel and a trapezoidal outward-expanding secondary reflection surface, and is arranged at the collector opening directly below the linear Fresnel lens, replacing a small part of the collector pipe wall, wherein the length of the rectangular channel is consistent with the thickness of the collector.

[0010] According to a preferred embodiment of the present invention, the opening angle of the secondary reflection surface of the daylighting window is 10° to 20°, and the inner wall of the rectangular channel and the surface of the secondary reflection surface are plated with a polished aluminum layer, so that they have a high reflectivity, the reflectivity can reach more than 90%, and the solar radiation loss caused by the reflection process is reduced. The opening width of the daylighting window accounts for a ratio of 10% to 15% of the circumference of the outer wall of the cavity solar collector.

[0011] According to a preferred embodiment of the present invention, the light-facing surface of the linear Fresnel lens is a smooth plane, and the backlight side is composed of triangular tooth structures arranged symmetrically on both sides, and the material is polymethyl methacrylate (PMMA) with high transparency. During the operation of the system, the bottom support frame can adjust the rotation angle of the entire system according to the solar altitude angle, so that the solar radiation is vertically incident on the system, ensuring the maximum radiation reception and the accuracy of focusing. The focus of the linear Fresnel lens coincides with the center of the heat absorption cavity (or, the central axis of the solar collector is located at the focus below the linear Fresnel lens, and the vertical distance is the focal length of the lens); when the sunlight is vertically incident, it is focused at the center of the heat absorption cavity and irradiated on the bottom micro-nano frequency division film, and the transmitted light will completely cover the photovoltaic cells under the frequency division film.

[0012] Solar radiation enters the thermal insulation cavity only through the daylighting opening, thereby constructing a cylindrical heat absorption cavity similar to a black body; the cylindrical cavity layer is made of high thermal insulation performance material, which wraps the internal heat absorber without exposing it to the outside, reducing heat radiation dissipation.

[0013] According to a preferred embodiment of the present invention, the high thermal insulation performance material used in the thermal insulation layer is composed of a hard thermal insulation material such as a ceramic fiberboard or a nano aerogel insulation board, and a filling layer such as high-temperature rock wool and aluminum silicate refractory fiber wool.

[0014] According to a preferred embodiment of the present invention, the heat-conducting working medium flowing in the outer working medium layer of the heat absorption cavity is water, and threaded fins are added to the inner side of the outer working medium layer of the heat absorption cavity to increase the contact area between the shell and tube, accelerate the heat conduction process, and heat the working medium to gas. The overall aspect ratio of the cavity solar collector is 10:1, and the ratio of the heat absorption cavity radius, the working medium layer thickness, and the insulation layer thickness is 4:3:3. Adding fins can increase the heat transfer efficiency by 60%, and can heat water to steam at about 373K.

[0015] According to a preferred embodiment of the present invention, the photovoltaic cell is located directly below the micro-nano film and fixed by the insulation layers on both sides. The photovoltaic cell adopts a gallium arsenide GaAs concentrating photovoltaic cell, and its solar power generation efficiency is about 29.7%. In addition, a water cooling device is installed on the back of the photovoltaic cell to ensure that the temperature of the photovoltaic cell will not be too high to affect the power generation efficiency, and it can also preheat the water.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The micro-nano film used in the solar frequency division PV / T system of the coupled micro-nano film and cavity collector proposed in the present invention has the characteristics of high temperature resistance, excellent frequency division effect, and low processing cost. The average transmittance in the spectral band of photovoltaic cells exceeds 90%, the spectral matching is high, and efficient solar frequency division utilization is achieved at low cost.

[0018] (2) The cavity collector used in the solar frequency division PV / T system of coupling micro-nano film and cavity collector proposed in the present invention is equipped with a linear Fresnel lens, and the collector is arranged below the linear Fresnel lens, avoiding the problems of high center of gravity and poor wind resistance in the traditional arrangement. The light window of the upper opening of the cavity collector used in the present invention is plated with a polished aluminum layer to reduce reflection loss, and the micro-nano frequency division film, solar cell and water cooling device are embedded in the bottom. The outer layer is arranged with multiple layers of insulation layer, and the gap between the micro-nano film and the solar cell is evacuated into a vacuum, so that the concentrated solar energy is divided and utilized in a cavity collector, and the energy dissipation to the outside is reduced, which effectively improves the conversion efficiency of solar energy. The cavity collector used in the present invention integrates the core components of the solar frequency division PV / T system into a cylindrical structure, realizes the integration of solar frequency division, photovoltaic power generation, and light-thermal utilization, realizes the miniaturization, lightness and low cost of solar frequency division utilization, and realizes the efficient and clean co-production of electricity and steam, which is of great significance for the promotion and popularization of solar frequency division technology.

[0019] (3) Through novel structural design and technological innovation, the present invention integrates a micro-nano frequency division film and a heat collection medium flow channel in a cavity collector, transmits the usable band of the solar spectrum (wavelength of 400nm to 900nm) to the photovoltaic cell for power generation, and reflects the remaining band to the inner wall of the surrounding heat absorption cavity for light and heat absorption, thus realizing compact and efficient operation of the PV / T system. Compared with other frequency division systems, the entire system is smaller in size, lower in cost, and more efficient.

[0020] (4) The photothermal capture component of the present invention adopts the heat-insulating cylindrical cavity structure of the cavity collector, combined with high absorption performance, high temperature resistance and selective absorption coating and high heat insulation performance materials, which can effectively reduce the heat radiation and heat convection loss in the heat collection process to less than 10%, improve the photothermal conversion efficiency, and heat the heat-conducting medium to gas state to achieve heat supply, heating, steam supply and other uses. The bottom support frame of the system can adjust the overall rotation angle of the system according to the solar altitude angle, so that the solar radiation is vertically incident on the system, ensuring the maximum radiation reception and the accuracy of focusing, and effectively realizing the efficient use of solar energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the working three-dimensional structure of the solar frequency division PV / T system of the present invention;

[0022] Figure 2 It is a cross-sectional structural schematic diagram of the cavity type solar collector of the present invention;

[0023] Figure 3 It is a schematic diagram of the three-dimensional structure of the cavity type solar collector of the present invention;

[0024] Figure 4 It is a schematic diagram of the three-dimensional structure of the lighting window of the present invention;

[0025] Figure 5 It is a structural schematic diagram of a three-dimensional view of the bottom bracket of the present invention.

[0026] Markings in the figure: lighting window 1, outermost thermal insulation layer 2, outer working medium layer of heat absorption cavity 3, cylindrical heat absorption cavity 4, micro-nano frequency division film 5, reflective material 6, concentrating photovoltaic cell 7, photovoltaic water cooling system 8, rectangular channel 5-1, trapezoidal outward-expanding secondary reflective surface 5-2. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention through specific examples and in conjunction with the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] like Figure 1 , Figure 2 and Figure 5 The present invention discloses a novel solar frequency-dividing PV / T system that couples a micro-nano film with a cavity collector, comprising a linear Fresnel lens, a cavity solar collector and a support frame; wherein the cavity solar collector comprises a cylindrical heat-absorbing cavity 4, an outer working medium layer 3 of the heat-absorbing cavity, and an outermost heat-insulating layer 2. Figure 2 and 3 As shown, the cavity solar collector is cylindrical in shape as a whole, and has a cylindrical cavity inside; two slots parallel to the axial direction are provided on the side wall of the cavity solar collector; the two slots are arranged opposite to each other. The length of the slots is selected according to the needs. In this embodiment, the lengths of the two slots are the same as the length of the cavity solar collector itself. A lighting window 1 is provided on one of the slots; a micro-nano frequency division film 5 is provided on the inner wall surface of the cylindrical heat absorption cavity 4 on the other slot facing it, and a concentrating photovoltaic cell 7 is installed on the thermal insulation layer 2 of the slot; the slot aperture between the micro-nano frequency division film 5 and the concentrating photovoltaic cell 7 is a cavity, and a reflective material 6 is avoided to be provided on the cavity.

[0029] The cavity solar collector is arranged directly below the central axis of the linear Fresnel lens, and its lighting window 1 is directly opposite to the central axis of the linear Fresnel lens. The bottom support frame of the system can adjust the rotation angle of the entire system according to the solar altitude angle, so that the solar radiation vertically enters the linear Fresnel lens.

[0030] When sunlight is irradiated, the bottom support frame system of the adjustment system is adjusted according to the solar altitude angle, and the rotation angle of the system is adjusted so that the solar radiation enters the system vertically. In this embodiment, the surface of the linear Fresnel lens facing the light side is a smooth plane, and the backlight side is composed of triangular tooth structures arranged symmetrically on both sides (symmetrically arranged about the central axis of the linear Fresnel lens), and the material is polymethyl methacrylate (PMMA) with high transparency. The linear Fresnel lens focuses the solar radiation incident on the system to the lighting window 1.

[0031] like Figure 4 The lighting window 1 is composed of a rectangular channel and a trapezoidal outward-expanding secondary reflection surface, and is arranged at the slot of the cavity solar collector directly below the linear Fresnel lens, replacing a part of the collector pipe, wherein the length of the rectangular channel is consistent with the thickness of the collector.

[0032] The opening angle of the trapezoidal outward-expanded secondary reflection surface 5-2 of the lighting window 1 is 10° to 20°, and the inner wall of the rectangular channel 5-1 and the surface of the trapezoidal outward-expanded secondary reflection surface 5-2 are both plated with a polished aluminum layer, so that they have a high reflectivity, which can reach more than 90%, reducing the solar radiation loss caused by the reflection process. The opening length of the lighting window accounts for a ratio of 10% to 15% of the circumference of the outer wall of the cavity-type solar collector, which ensures that the focusing light path is not blocked, ensures high sunlight capture efficiency, and reduces the dissipation of cavity heat radiation escaping to the outside. In this embodiment, the ratio of the heat absorption cavity radius, the working fluid layer thickness, and the insulation layer thickness is 4:3:3.

[0033] The solar radiation focused on the lighting window 1 enters the heat absorption cavity 4 under the reflection effect of the inner wall of the rectangular channel 5-1 and the aluminum-plated layer on the surface of the trapezoidal outward-expanding secondary reflection surface 5-2.

[0034] Solar radiation enters the heat absorption cavity 4 only through the lighting window 1, thereby constructing a cylindrical heat absorption cavity similar to a black body; the thermal insulation layer adopts high thermal insulation performance material, wraps the internal heat absorption cavity 4 without being exposed, and reduces heat radiation dissipation.

[0035] The high thermal insulation performance material used in the thermal insulation layer is composed of hard thermal insulation material such as ceramic fiber board or nano aerogel insulation board, and filling layer such as high-temperature rock wool and aluminum silicate refractory fiber wool, wherein the hard thermal insulation material is on the outside and the filling layer is on the inside.

[0036] Micro-nano frequency division film 5 is TiO 2 and SiO 2The optical interference multilayer frequency division film is a film in which materials are alternately deposited on a transparent substrate. In this embodiment, it is processed by magnetron sputtering technology, and the material is a three-layer structure, which is SiO 2 / TiO 2 / SiO 2 The thickness is 100nm / 300nm / 150nm respectively, the transmittance is more than 90% between 400nm-900nm, the transmittance is up to 99.1% at 460nm, and the average transmittance is 93.88%. The film has a simple structure and is easy to process and manufacture, which is conducive to large-scale production.

[0037] When the solar radiation entering the heat preservation cavity is irradiated on the micro-nano frequency division film 5, the micro-nano frequency division film 5 selectively transmits the solar radiation. The wavelength of 400nm to 900nm is the part of the band that can be used by photovoltaic cells. It will be transmitted to the concentrating photovoltaic cell 7 below to generate electricity, and the remaining band will be reflected to the inner wall of the surrounding heat absorption cavity 4.

[0038] The inner wall of the heat absorption cavity 4 is coated with a heat absorption coating with high absorption performance and high temperature resistance, and its composition is composed of high temperature resistant resin, light absorbing pigment, solvent, dispersant and filler, and the mass fraction ratio is 15%:12%:65%:2%:6%, wherein the high temperature resistant resin is vinyl cage type polysilsesquioxane; the light absorbing pigment is a mixture of copper oxide, ferroferric oxide and manganese oxide nanoparticles, and the mass fraction is 1:1:1; the solvent is xylene; the dispersant is the wetting dispersant DISPERSANT-2070; the filler is rare earth yttrium; the coating coating thickness is 30μm, and it has an absorption rate of more than 90% and an emissivity of less than 30%. The residual band energy of solar radiation that cannot be used by photovoltaic cells is absorbed into a large amount of heat energy.

[0039] Threaded fins are provided on the inner side of the outer working medium layer 3 of the heat absorption cavity to increase the contact area between the shell and tube, accelerate the process of the heat absorption cavity 4 transferring a large amount of heat energy to the working medium (in this embodiment, the working medium is water), and quickly heat the working medium water to the gas phase.

[0040] The photovoltaic cell 7 is located directly below the micro-nano frequency division film 5 and is fixed by the insulation layers on both sides. The photovoltaic cell 7 is a gallium arsenide GaAs concentrating photovoltaic cell, and its solar power generation efficiency is about 29.7%.

[0041] A water cooling device is installed on the back of the photovoltaic cell 7 to ensure that the temperature of the photovoltaic cell will not be too high and affect the power generation efficiency. In addition, the water cooling device can preheat the water, and then enter the working medium layer to heat it into steam.

[0042] According to the simulation calculation of the model established by this system, the photoelectric efficiency of photovoltaic cells can reach 31.28%, and the photothermal efficiency based on the cavity insulation structure system is greatly improved. The overall energy utilization efficiency of the system can reach 84.25%, which is more than 9.65% higher than the traditional linear Fresnel concentrating PV / T system that first divides the frequency and then concentrates the light.

[0043] The specific implementation cases described in this specification are examples of the invention structure, and the names of the various structures therein may be different. The structure of the invention is not limited to the above-mentioned implementation methods. Any equivalent or simple changes made based on the structure or principle of the patent of the invention should fall within the scope of protection of this application.

Claims

1. A solar frequency-divided PV / T system coupling micro-nano film and cavity collector, characterized in that: The invention comprises a linear Fresnel lens and a cavity solar thermal collector; wherein the cavity solar thermal collector comprises, from the inside to the outside, a cylindrical heat absorbing cavity (4), a working fluid layer (3) wrapped in the outer layer of the heat absorbing cavity, and a heat preservation and heat insulating layer (2) wrapped in the working fluid layer; the cavity solar thermal collector is provided with a lighting window (1) on the side wall along the axial direction, and a micro-nano frequency division film (5) is provided on the inner wall surface of the heat absorbing cavity (4) facing the lighting window (1), a concentrating photovoltaic cell (7) is provided below the micro-nano frequency division film (5), a vacuum cavity is provided between the micro-nano frequency division film (5) and the concentrating photovoltaic cell (7), and a reflective material (6) is provided on the wall surface of the vacuum cavity; The cavity-type solar thermal collector is arranged directly below the symmetrical central axis of the linear Fresnel lens, and the light-collecting window (1) directly faces the linear Fresnel lens. The linear Fresnel lens focuses incident solar radiation onto the light-collecting window (1), and irradiates the solar radiation onto the micro-nano frequency-dividing film (5) in the heat-absorbing cavity through the light-collecting window (1).

2. The solar frequency-divided PV / T system of coupling micro-nano film and cavity collector according to claim 1, characterized in that: The linear Fresnel lens and the cavity solar collector are fixedly connected to maintain the relative position between the two; the system also includes a support frame system, which is used to adjust the rotation angle of the solar frequency division PV / T system so that the solar radiation is vertically incident on the linear Fresnel lens.

3. The solar frequency-divided PV / T system of coupling micro-nano film and cavity collector according to claim 1, characterized in that: The micro-nano frequency division film (5) is arranged on the inner wall surface of the heat absorption cavity (4) opposite to the light-collecting window (1), and is an optical interference multilayer frequency division film formed by alternately depositing two materials, TiO2 and SiO2, on a transparent substrate, and is used to achieve a selective transmission effect on the solar spectrum, transmitting a portion of the wavelength band of 400nm to 900nm to the photovoltaic cell (7) below for power generation, and reflecting the remaining band to the inner wall of the heat absorption cavity (4).

4. The solar frequency-divided PV / T system of coupling micro-nano film and cavity collector according to claim 3 is characterized in that: The micro-nano frequency division film (5) is obtained by magnetron sputtering technology, and the material has a three-layer structure, which is SiO2, TiO2 and SiO2 from top to bottom, with thicknesses of 100nm, 300nm and 150nm respectively, and the transmittance between 400nm and 900nm is more than 90%.

5. The solar frequency division PV / T system of coupling micro-nano film and cavity collector according to claim 1, characterized in that: The lighting window (1) is composed of mutually connected rectangular channels and a secondary reflection surface that expands outward in a trapezoidal shape, wherein the rectangular channel is a window provided on the cavity solar collector, the length of the channel is consistent with the thickness of the cavity solar collector, and the secondary reflection surface is located outside the cavity solar collector, with its opening facing the linear Fresnel lens.

6. The solar frequency-divided PV / T system of coupling micro-nano film and cavity collector according to claim 5, characterized in that: The opening angle of the secondary reflection surface is 10° to 20°, the inner wall of the rectangular channel and the surface of the secondary reflection surface are both plated with a polished aluminum layer; the opening width of the lighting window accounts for 10% to 15% of the circumference of the outer wall of the cavity solar collector.

7. The solar frequency-divided PV / T system of coupling micro-nano film and cavity collector according to claim 1, characterized in that: The light-facing surface of the linear Fresnel lens is a smooth plane, and the backlight side is composed of triangular tooth structures arranged symmetrically on both sides, and the material is polymethyl methacrylate (PMMA); the lighting window is located directly below the symmetric central axis of the linear Fresnel lens; the focus of the linear Fresnel lens coincides with the center of the heat absorption cavity; when sunlight is vertically incident, it is focused at the center of the heat absorption cavity and then irradiated on the bottom micro-nano frequency division film, and the transmitted light will completely cover the photovoltaic cell under the frequency division film.

8. The solar frequency-divided PV / T system of coupling micro-nano film and cavity collector according to claim 1, characterized in that: The thermal insulation layer (2) is made of a material with high thermal insulation performance, which wraps the internal heat absorption cavity without exposing it to the outside, thereby reducing heat radiation dissipation; the material with high thermal insulation performance used in the thermal insulation layer (2) is composed of a hard thermal insulation material and a filling layer; the heat-conducting working medium flowing in the working medium layer (3) is water, and threaded fins are added to the inner side of the working medium layer (3) to increase the contact area with the heat absorption cavity (4), thereby accelerating the heat conduction process and heating the working medium to gas.

9. The solar frequency-divided PV / T system of coupling micro-nano film and cavity collector according to claim 1, characterized in that: The concentrating photovoltaic cell (7) is arranged at the thermal insulation layer (2), and its two sides are fixed by the thermal insulation layer (2). The concentrating photovoltaic cell (7) adopts a gallium arsenide GaAs concentrating photovoltaic cell, and a water cooling device (8) is installed on the back of the photovoltaic cell to ensure that the temperature of the photovoltaic cell will not be too high and affect the power generation efficiency.

10. A method for utilizing solar energy based on the system according to any one of claims 1 to 9, characterized in that include: Solar radiation is incident vertically on a linear Fresnel lens; the linear Fresnel lens focuses the solar radiation incident on the system to the daylighting window, which is then reflected by the daylighting window and collected into the heat absorption cavity, and irradiated onto the bottom micro-nano film; wherein the solar radiation enters the cavity-type solar collector only through the daylighting window; When the solar radiation entering the cavity solar collector irradiates the micro-nano frequency division film, the micro-nano frequency division film selectively transmits the solar radiation, and partially transmits the wavelength band of 400nm to 900nm into the reflective cavity below. With the assistance of the reflective material arranged in the reflective cavity, the radiation entering the reflective cavity is absorbed by the concentrating photovoltaic cell and generates electricity, and the micro-nano frequency division film reflects the remaining band to the inner wall of the heat absorption cavity. The inner wall of the heat absorption cavity is coated with selective absorption coating, which absorbs all the energy of the remaining band of solar radiation into heat energy. The heat absorption cavity conducts the absorbed heat energy to the working fluid layer to heat the flowing working fluid, thereby realizing the energy utilization of the full spectrum of the sun.

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