Photovoltaic photo-thermal comprehensive utilization system based on optimization of tower type photo-thermal power station

Abstract

The invention discloses a photovoltaic and photo-thermal comprehensive utilization system based on tower type photo-thermal power station optimization, and belongs to the technical field of power generation. According to the invention, by optimizing the structure of the concentrating tower, the original traditional scheme of directly concentrating light to a heat receiver from a reflecting mirror field is optimized into a two-stage reflection design, that is, the reflecting mirror field is used as first-stage reflection, the position of a frequency division film is used as second-stage reflection, and a photovoltaic cell and the frequency division film are placed at the second-stage reflection position. A frequency division film is plated on the surface of a photovoltaic cell panel, so that visible light high-grade energy wave band transmission and absorption are improved, reflection of visible light and low-grade infrared light to a certain degree is maintained, normal operation of a condensation type photo-thermal system is guaranteed, spatial separation of high-grade visible light photon energy and low-grade near-infrared light photon energy is completed, and the energy efficiency is improved. Therefore, frequency division utilization of solar energy is achieved, solar energy utilization is achieved in a mode of combining a photovoltaic system and a photo-thermal system, and the power generation efficiency is improved. The system is suitable for solar power generation combining a photovoltaic system and a photo-thermal system.

Description

Technical Field

[0001] The present invention belongs to the technical field of power generation, and in particular relates to a photovoltaic and thermal comprehensive utilization system based on optimization of a tower-type solar thermal power station. Background Art

[0002] As a clean energy source that can be used sustainably, solar energy has broad development prospects. At present, the main ways to utilize solar energy in the market are photovoltaic power generation and solar thermal power generation. Among them, tower solar power generation technology, as a form of solar thermal power generation, has broad prospects for large-scale application. However, due to its low utilization rate of high-quality photon energy (visible light band), solar thermal power generation can achieve frequency-divided utilization of photovoltaic and thermal energy and improve the utilization efficiency of high-quality photon energy by optimizing tower solar thermal power stations, which is of great significance to improving the power generation efficiency of tower solar thermal power stations.

[0003] In the traditional concentrated solar power generation technology, in the process of converting light energy into heat energy and then into electrical energy through heat conversion, the quality of high-quality photon energy is reduced due to the light-to-heat conversion, which is not conducive to improving the efficiency of the power generation system. This is particularly disadvantageous for the energy utilization of higher-energy photons, especially photons in the visible light band that occupy the main range of the solar spectrum. Therefore, it is particularly important to realize the comprehensive utilization of photovoltaic and thermal systems.

[0004] As a concentrated solar thermal power generation technology, tower solar thermal power generation uses an array of heliostats that independently track the sun to concentrate sunlight onto a heat receiver fixed on the top of the tower to heat the working fluid, thereby generating high-temperature gas to drive a steam turbine or gas generator set. Due to the large initial investment in tower power plants, heliostats account for 52%. The initial cost of building a mirror field also means that the traditional frequency division method of directly adding photovoltaic cells to flat reflectors will inevitably increase excessive financial burdens, which also reduces the advantages of large-scale commercial use of solar energy and limits the promotion and use of concentrated solar thermal.

[0005] After studying and analyzing the focusing and frequency division system, it was found that the introduction of the frequency division film solves the problem of high-quality energy utilization in the photothermal system. At the same time, it recovers the solar energy band energy that cannot be used by photovoltaic cells, which has a positive impact on improving the comprehensive utilization of sunlight and improving the photoelectric conversion efficiency.

[0006] For tower solar power generation technology, the complexity of the heliostat field causes large differences in the angle of incidence of sunlight on the split-band film, and the large angle of incidence has a great impact on the transmittance of the split-band film. Therefore, how to design the split-band film so that it can still maintain good spectral transmittance under complex incident angle conditions is an important research issue.

[0007] In traditional concentrated solar thermal systems, sunlight usually hits the reflector at a large incident angle. If solar panels are installed directly at the reflector position for photovoltaic power generation, the scale of the reflector array of the concentrated solar thermal system will bring about cost issues in system construction. At the same time, according to the Fresnel equation, when sunlight hits at a large incident angle, most of the radiation energy will be reflected, resulting in low radiation absorption rate of photovoltaic cells, which seriously affects the photoelectric conversion efficiency of photovoltaic cells under large incident angle conditions. Summary of the invention

[0008] The present invention provides a photovoltaic and thermal comprehensive utilization system based on the optimization of a tower-type solar thermal power station, which is used to solve the problems mentioned in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] The present invention provides a photovoltaic and thermal comprehensive utilization system based on the optimization of a tower-type solar thermal power station, the system comprising a primary reflection position and a secondary reflection position;

[0011] The primary reflection position is used to set the reflector array, and the secondary reflection position is used to set the photovoltaic panel and the frequency division film;

[0012] The frequency division film is plated on the surface of the photovoltaic cell panel;

[0013] The reflector array is used to reflect sunlight to the frequency-dividing film;

[0014] The high-quality visible light photon energy in the sunlight is transmitted through the frequency-dividing film to enter the photovoltaic cell panel for photovoltaic power generation, and the remaining energy in the sunlight is reflected through the frequency-dividing film to the collector for photothermal power generation.

[0015] Furthermore, in another preferred embodiment, the plane equation of the photovoltaic panel is:

[0016] H=K MN (XX M )+H M

[0017] Among them, K MN =tanα, α is the inclination angle of the photovoltaic panel, H M is the installation height of the photovoltaic panel, X M is the horizontal coordinate of the photovoltaic panel in the plane equation.

[0018] Furthermore, in another preferred embodiment, the slope K of the i-th reflector is i for:

[0019]

[0020] The width of the i-th reflector is L i for:

[0021]

[0022] The coordinates of the i-th reflector are:

[0023]

[0024] Among them, β i is the inclination angle of the i-th reflector, W is the width of the photovoltaic panel, X Mi and X Ni Respectively represent the starting point M of the i-th reflector i and end point N i The horizontal axis of .

[0025] Furthermore, in another preferred embodiment, the frequency division film is a multilayer film in which high refractive index materials and low refractive index materials are alternately stacked, and the high refractive index material serves as the surface layer.

[0026] Furthermore, in a preferred embodiment, the number of layers of the multilayer film is 13.

[0027] Furthermore, there is another preferred embodiment, the periodic structure film system of the above-mentioned frequency division film is:

[0028] Air / (aHbL)^m / Sub

[0029] Among them, Air represents the sunlight incident on the air, H is the high refractive index material TiO2, L is the low refractive index material SiO2, a is the thickness of the TiO2 film layer, b is the thickness of the SiO2 film layer, m is the number of periodic film layers, and Sub is the metal substrate Al.

[0030] Furthermore, in another preferred embodiment, the spectral reflectivity ρ and spectral transmittance τ of the above-mentioned frequency division film are respectively:

[0031]

[0032] Where λ is the wavelength of solar radiation.

[0033] Furthermore, in a preferred embodiment, the photovoltaic cell panels are monocrystalline silicon cells.

[0034] Furthermore, in a preferred embodiment, an aluminum mirror is added to the bottom of the photovoltaic cell panel to reflect the solar radiation transmitted by the frequency-splitting film back to the photovoltaic cell panel.

[0035] Furthermore, in a preferred embodiment, a reflector is provided below the above-mentioned collector for secondary reflection of the sunlight not absorbed by the collector and re-focusing it on the collector.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention processes the surface of photovoltaic panels based on the principle of micro-nanoscale radiation regulation to construct a layer of solar frequency-splitting film, which improves the transmission and absorption of high-quality energy bands of visible light while maintaining a certain degree of reflection of visible light and low-quality infrared light, ensuring the normal operation of the concentrated photothermal system, and completing the spatial separation of high-quality visible light photon energy and low-quality near-infrared photon energy, thereby realizing the frequency-splitting utilization of solar energy, realizing the utilization of solar energy by combining photovoltaic and photothermal systems, and improving power generation efficiency.

[0038] Furthermore, the present invention optimizes the focusing tower structure, and optimizes the traditional solution of directly focusing light to the heat receiver by the reflector field into a two-stage reflection design, that is, the reflector field is used as the primary reflection, the location of the frequency division film is the secondary reflection, and the photovoltaic cell and the frequency division film are placed at the secondary reflection position, and the frequency division utilization of solar energy can be achieved through a small number of photovoltaic panels. Compared with the existing focusing tower frequency division solution by adding a large number of photovoltaic cells to the reflector field, the present invention greatly reduces the cost problem caused by the introduction of photovoltaic cells. Therefore, the present invention belongs to an invention creation that is different from the prior art concept.

[0039] 2. Compared with other focusing methods, the light field of the focusing tower beam is more complicated. There is often a situation where the incident light is incident on the reflector at a large angle, which will increase the reflectivity of the light on the frequency-dividing film and affect the frequency-dividing performance of the frequency-dividing film. According to the principle of micro-nanoscale radiation regulation, the present invention processes a layer of solar frequency-dividing film on the surface of the solar panel, and the solar frequency-dividing film is a periodic structure film. By designing the structural parameters of the periodic film layer, it can not only solve the high reflectivity problem caused by the large incident angle of light, but also achieve high transmittance in the visible light band and high reflectivity in the infrared band, improve the utilization rate of photovoltaic cells, and reduce the heat load caused by the infrared band energy.

[0040] The present invention is applicable to solar power generation combining photovoltaic and photothermal systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 It is a schematic diagram of the optimized structure of the tower-type concentrated solar thermal power station described in the present invention;

[0043] Figure 2 is a schematic diagram of the single-side geometric design of the concentrator according to the present invention;

[0044] Figure 3 It is the propagation path of the light beam in the periodic film system described in the present invention.

[0045] Figure 4 is a schematic diagram of the optimized spectrum frequency division film structure of the present invention;

[0046] Figure 5 is the optimized spectrum splitting film reflection spectrum characteristic curve of the present invention;

[0047] Figure 6 This is a performance comparison diagram of the ideal frequency division film and the multi-layer frequency division film described in the present invention;

[0048] Figure 7 The effect of the incident angle of sunlight on the performance of the 13-layer frequency division film described in the present invention;

[0049] Figure 8 This is a simulation diagram of the electric field analysis of the 13-layer frequency division membrane structure of the present invention at a wavelength of λ=700nm;

[0050] Fig. 9 This is a simulation diagram of electric field analysis of the 13-layer frequency division membrane structure of the present invention at a wavelength of λ=1300nm;

[0051] Fig.10 It is the direct sunlight spectrum curve and the average reflectivity curve of the multilayer optical film described in the present invention. DETAILED DESCRIPTION

[0052] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0053] Implementation method 1, see Figure 1 This embodiment is described. This embodiment provides a photovoltaic and thermal comprehensive utilization system based on the optimization of a tower-type solar thermal power station. The system includes a primary reflection position and a secondary reflection position.

[0054] The primary reflection position is used to set the reflector array, and the secondary reflection position is used to set the photovoltaic panel and the frequency division film;

[0055] The frequency division film is plated on the surface of the photovoltaic cell panel;

[0056] The reflector array is used to reflect sunlight to the frequency-dividing film;

[0057] The high-quality visible light photon energy in the sunlight is transmitted through the frequency-dividing film to enter the photovoltaic cell panel for photovoltaic power generation, and the remaining energy in the sunlight is reflected through the frequency-dividing film to the collector for photothermal power generation.

[0058] In practical application, this embodiment uses a spectrum splitting film to optimize the photovoltaic / photothermal system of the original tower-type concentrated solar power station structure, such as Figure 1 As shown, the tower-type concentrating solar thermal power station designed in this embodiment is mainly divided into two levels of reflective focusing in structure: the first level of reflective focusing is that the sunlight is incident on the reflector array and then optically reflected to form a focusing band with higher radiation flux. The second level of reflective focusing is to plate the spectrum frequency division film on the surface of the photovoltaic cell panel, and complete the spectrum frequency division function through a layer of selectively transparent film system. The photon energy in the visible light region and other bands that can be responded to by the photovoltaic cell can be transmitted through the spectrum frequency division film into the photovoltaic cell to perform photovoltaic power generation. The invalid solar radiation outside the corresponding photovoltaic band is reflected on the surface of the spectrum frequency division film and irradiated onto the collector, and then the reflector is used to reflect most of the sunlight that is not absorbed by the collector for a second time, so that the leaked sunlight is re-focused on the collector, thereby increasing the radiation intensity received by the collector, which is used to heat the heat-conducting medium in the collector, complete the solar thermal power generation, and realize the utilization of solar energy by combining photovoltaic and solar thermal systems to improve the power generation efficiency.

[0059] Implementation Method 2: See Figure 2 This embodiment is described. This embodiment specifically describes the geometric position of the photovoltaic and thermal comprehensive utilization system based on the optimization of the tower-type thermal power station described in the first embodiment.

[0060] Figure 2 MN in represents the photovoltaic cell panel and the spectrum frequency division film coated on its surface. Its two end boundary points are M and N respectively. The photovoltaic cell surface MN gathers the solar radiation reflected by the reflector array of the focusing system. Ni represents the reflector array point, Mi and Ni represent the starting point and end point of the i-th reflector respectively. i and K i They represent the inclination angle and slope of the i-th reflector, that is, K i =tanβ i Li represents the width of the plane reflector unit, W represents the width of the solar panel, α represents the inclination angle of the solar panel, H M Indicates the installation height of photovoltaic panels.

[0061] By X N =Wcosα,H N =H M+Wsinα, we know that the plane equation of the photovoltaic panel is:

[0062] H=K MN (XX M )+H M

[0063] In the formula, K MN =tanα, taking the starting point M of the reflector as the reference, let the horizontal and vertical coordinates of the starting point M1 of the first plane reflector be X N1 , H N1 .

[0064] The slope and plane equation corresponding to the first plane mirror M1N1 are:

[0065]

[0066] H=K1(XX M1 )

[0067] When designing the geometric parameters of the concentrator, it is assumed that the sunlight reflected by point Ni of each plane reflector passes through point N on the surface of the photovoltaic cell, that is, the sunlight reflected by the concentrator reflector array converges on the surface of the spectrum frequency division film. Then the coordinate formula of the end point N1 of the first plane reflector is:

[0068]

[0069] By analogy, in the i-th reflector unit, the calculation formula for its related structural parameters is:

[0070]

[0071] Among them, β i is the inclination angle of the i-th reflector, W is the width of the photovoltaic panel, X Mi and X Ni Respectively represent the starting point M of the i-th reflector i and end point N i The horizontal axis of .

[0072] According to the definition of the theoretical geometric concentration ratio of the concentrator, it is the ratio of the concentrator light collection area S1 to the receiver area S2, which is represented by CR. For the system proposed in this embodiment, the receiver area is the surface area of ​​the photovoltaic cell, and the width of the photovoltaic cell panel is W. Then the theoretical geometric concentration ratio CR of the concentrator is:

[0073]

[0074] The corresponding focusing ratio is obtained according to the geometric structure of the reflector array of different focusing systems, as shown in Table 1 below:

[0075] i <![CDATA[X Mi (m)]]> <![CDATA[X Ni (m)]]> <![CDATA[β i (°)]]> <![CDATA[K i ]]> <![CDATA[L i (m)]]> CR 1 2 0.030 2.86 0.05 0.60 1.0 2 4 0.058 5.66 0.10 0.62 2.0 3 6 0.084 8.35 0.15 0.63 3.1 4 8 0.107 10.90 0.19 0.66 4.1 5 10 0.127 13.28 0.24 0.70 5.3 6 12 0.142 15.48 0.28 0.75 6.5 7 14 0.155 17.50 0.32 0.81 7.8 8 16 0.164 19.33 0.35 0.88 9.2 9 18 0.171 20.99 0.38 0.98 10.7 10 20 0.176 22.50 0.41 1.11 12.4 11 22 0.179 23.86 0.44 1.28 14.3 12 24 0.180 25.10 0.47 1.51 16.6 13 26 0.180 26.22 0.49 1.86 19.4 14 28 0.180 27.23 0.51 2.41 23.0 15 30 0.178 28.16 0.54 3.45 28.0

[0076] Table 1

[0077] From Table 1, it can be seen that the appropriate concentration ratio of the concentrating system can be obtained by designing the reflector field, and the size of the concentration ratio directly affects the efficiency of the concentrated photovoltaic and concentrated solar thermal systems. With the help of the previous analysis of the geometric relationship of the concentrating system, a reference is provided for the geometric design of the reflector field.

[0078] Implementation method three, see Figure 3 This embodiment is described below. This embodiment is a specific description of the frequency division film described in the first embodiment.

[0079] The frequency division film is a multilayer film in which high refractive index materials and low refractive index materials are alternately stacked, and the high refractive index material serves as the surface layer.

[0080] In practical application, in order to realize the frequency division of the solar spectrum, this embodiment adopts a multi-layer optical film design scheme, and the specific design process is based on the relevant parameters of single crystal silicon cells (c-Si). The optical parameters of the frequency division film are as follows:

[0081]

[0082] Where ρ and τ represent the spectral reflectance and spectral transmittance of the frequency-splitting film, respectively, and λ represents the wavelength of solar radiation.

[0083] Using high refractive index materials as the surface layer of the periodic film layer can obtain more light transmission compared to other frequency-dividing film materials. This can also solve the problem of high reflectivity caused by large incident angles of light and bring more energy input to photovoltaic cells. By designing the structural parameters of the periodic film layer, high transmittance in the visible light band and high reflectivity in the infrared band can be achieved, which can improve the utilization rate of photovoltaic cells while reducing the heat load caused by infrared band energy.

[0084] Among them, the working principle of designing the periodic membrane structure parameters is:

[0085] like Figure 3 As shown in the figure, periodic structure film is the basis of optical film design. The important feature of this structure is that low transmittance and high transmittance spectra appear alternately. The low transmittance area and the high transmittance area are used to control the wavelength spectrum. When light passes through a layered medium, the reflected light and the transmitted light from different interfaces produce light interference in the incident and reflected directions of the light. By using this interference phenomenon, the interference of light can be controlled by changing the material and its thickness and other characteristics, and the redistribution of light energy can be achieved according to actual needs.

[0086] The periodic structure film system of the frequency division film is:

[0087] Air / (aH bL)^m / Sub

[0088] Among them, Air represents the sunlight incident on the air; H is the high refractive index material TiO2, L is the low refractive index material SiO2, a is the thickness of the TiO2 film layer, b is the thickness of the SiO2 film layer; m is the number of periodic film layers; Sub is the metal substrate Al.

[0089] Embodiment 4: This embodiment is a specific description of the number of layers of the multilayer optical film described in the above embodiment;

[0090] As a best embodiment, this implementation selects a 13-layer multilayer optical film.

[0091] Implementation method 5: See Figures 4 to 9 The present embodiment is described as follows. In the present embodiment, an aluminum mirror is added to the bottom of the photovoltaic cell panel described in the above embodiment to reflect the solar radiation transmitted by the frequency-splitting film.

[0092] In actual application of this embodiment, the spectral characteristics of the frequency-dividing film structure are analyzed through the transfer matrix method. In the analysis of the spectral characteristic curves of the designed frequency-dividing film at different incident angles, it is found that: in the infrared short-wavelength band (1100-1500nm), the frequency-dividing film has good frequency-dividing performance, and even under the condition of 50° incident angle of sunlight, the average reflectivity can still be maintained above 70%; while in the infrared long-wavelength band (1500-2500nm), due to the inherent properties of the optical film, the performance of the frequency-dividing film is poor, which has a great restriction on improving the spectrum utilization. To solve this problem, this embodiment optimizes the design of the designed 13-layer multilayer optical thin film system, and adds an aluminum mirror at the bottom of the single crystal silicon (c-Si) cell to re-reflect the transmitted solar radiation, thereby solving the problem of low reflectivity of the infrared long wavelength, and optimizing the frequency-dividing film structure such as Figure 4 The 13-layer multilayer optical thin film system is shown in Table 2 below, where H represents a high refractive index film layer (TiO2) and L represents a low refractive index film layer (SiO2).

[0093] Number of layers Material Thickness(μm) Number of layers Material Thickness(μm) 1 H 0.152 8 L 0.225 2 L 0.225 9 H 0.152 3 H 0.152 10 L 0.225 4 L 0.225 11 H 0.152 5 H 0.152 12 L 0.225 6 L 0.225 13 H 0.225 7 H 0.152

[0094] Table 2

[0095] Furthermore, the embodiment also re-analyzes the reflection spectrum of the optimized frequency-dividing membrane structure at different incident angles and compares it with the ideal frequency-dividing membrane. Figure 5As shown in the figure, the results show that the optimized frequency-dividing film maintains good frequency-dividing performance in the 300-1100nm band and the 1100-2500nm band, meeting the design requirements of the spectrum frequency-dividing film. At the same time, the study of the spectral curves at different incident angles shows that the incident angle of sunlight has little effect on the optimized frequency-dividing film, which also meets the design requirements of the frequency-dividing film for the concentrated frequency-dividing photovoltaic and thermal comprehensive utilization system.

[0096] Furthermore, in order to verify that the 13-layer optical film has the best effect, the following simulation analysis was performed:

[0097] The average reflectivity of the multi-layer frequency division film is shown in Table 3 below:

[0098]

[0099] Table 3

[0100] Through simulation analysis, we get Figure 6 As shown in the performance curve of the ideal frequency-dividing film and the multi-layer frequency-dividing film, it can be seen from the figure that under the action of the aluminum mirror on the back panel, the reflectivity performance of the band after 1500nm is basically the same; with the increase of the film layer in the 1100nm~1500nm band, the reflectivity gradually increases, which means that more sunlight that cannot be absorbed by the photovoltaic cell is reflected into the photothermal system, that is, the ineffective heat load of the photovoltaic cell is reduced, which is beneficial to improving the performance of the photovoltaic system.

[0101] Taking into account the film layer processing technology, the more film layers there are, the greater the processing difficulty. Therefore, a 13-layer frequency division film is selected as the frequency division device to reduce the processing difficulty requirement while ensuring the frequency division capability.

[0102] At the same time, the influence of the incident angle of sunlight on the performance of the 13-layer frequency-dividing film was simulated, and the following results were obtained: Figure 7 As shown in the simulation diagram, it can be seen that in the range of incident angle 0 to 60°, the frequency-dividing film maintains excellent frequency-dividing performance and has good adaptability to the incident light within the range of 60° incident angle, enabling it to work normally under the complex incident angle conditions of the tower-type focusing reflector field and realize the function of spectral frequency division.

[0103] The electric field of the 13-layer frequency-dividing membrane structure at different wavelengths was also analyzed, and the following results were obtained: Figure 8 and Fig. 9 As shown in the simulation diagram, it can be seen from the figure that Figure 8 At a wavelength of 700nm (representing the situation of sunlight in the transmission band), the distribution of strong and weak electric fields roughly presents a periodic distribution in the direction of the film layer. The energy of sunlight at this wavelength can be normally transmitted through the frequency-dividing film and absorbed by the photovoltaic cells in the lower layer. Fig. 9At 1300nm (representing the reflection band of sunlight), the electric field is mainly distributed in the surface area of ​​the splitter film, that is, the sunlight energy in this band cannot be transmitted into the photovoltaic cell under the action of the splitter film, and most of it is reflected to the collector system for photothermal utilization.

[0104] Implementation Method 6: See Fig.10 This embodiment is described. This embodiment is to verify the above-mentioned embodiment of coating a multilayer optical thin film system on the surface of a photovoltaic cell panel to achieve the frequency division of the sunlight spectrum.

[0105] The optical film scheme designed in this embodiment realizes the frequency division of the sunlight spectrum by coating a multi-layer optical film system on the surface of the photovoltaic cell to improve the photoelectric conversion efficiency and the overall efficiency of the system. Ideally, the frequency division film increases the solar radiation transmittance in the photovoltaic cell response band while increasing the reflection of other bands.

[0106] Combined with Fig.10 The direct sunlight spectrum curve and the average reflectivity curve of the multi-layer optical film design are shown to analyze the radiation absorption of the photovoltaic cell after the frequency division film: the total solar radiation energy in the wavelength range of 300-2500nm is 870W / m 2 After the frequency division film acts, about 80% of it is about 697W / m 2 The radiation energy absorbed by photovoltaic cells accounts for 95.8% of the radiation energy in the photovoltaic power generation spectrum response band (300-1100nm) in the direct sunlight spectrum. Most of the remaining reflected energy is invalid heat load that cannot be absorbed by photovoltaic cells, which is undoubtedly beneficial to maintaining the normal working temperature of photovoltaic cells and can also greatly reduce the heat dissipation requirements of photovoltaic subsystems.

[0107] In summary, the selection of photovoltaic subsystem parameters in the concentrated frequency-divided photovoltaic thermal system described in the above implementation is consistent with the photovoltaic cell under pure concentration conditions. For the photothermal utilization part, the collector temperature is assumed to be 500°C and the ambient temperature is 25°C. Based on the formula The reflected solar energy is 3763W. The diameter of the collector is 1.0m, the average absorptivity and average transmittance are assumed to be 0.95, and the collector reflectivity is approximately expressed as 2×10 -7 T t 2 +5×10 -5 T t +0.05. Through calculation and analysis, it can be obtained that the comprehensive efficiency of the designed concentrated frequency-divided photovoltaic and thermal comprehensive utilization system is 26.6%.

[0108] The results show that the output power of the photovoltaic subsystem in the system designed in the above embodiment is 5375W, and the output power of the photothermal subsystem is 941W. The photovoltaic conversion efficiency and photothermal power generation efficiency of the system are 27.1% and 25.0% respectively, and the total energy conversion efficiency of the system is 25.7%. Compared with the photoelectric conversion efficiency under the condition of pure concentration, it can be seen that the efficiency of the photovoltaic and photothermal subsystems is higher than that of the pure concentration system.

[0109] The above description is only the implementation mode of the present invention and is not limited to the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A photovoltaic and thermal comprehensive utilization system based on the optimization of a tower-type solar thermal power station, characterized in that: The system includes a primary reflection position and a secondary reflection position; The primary reflection position is used to set the reflector array, and the secondary reflection position is used to set the photovoltaic panel and the frequency division film; The frequency division film is plated on the surface of the photovoltaic cell panel; The reflector array is used to reflect sunlight to the frequency-dividing film; The high-quality visible light photon energy in the sunlight is transmitted through the frequency-dividing film to enter the photovoltaic cell panel for photovoltaic power generation, and the remaining energy in the sunlight is reflected through the frequency-dividing film to the collector for photothermal power generation.

2. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 1 is characterized in that: The plane equation of the photovoltaic panel is: H=K MN (X-X M )+H M Among them, K MN =tanα, α is the inclination angle of the photovoltaic panel, H M is the installation height of the photovoltaic panel, X M is the horizontal coordinate of the photovoltaic panel in the plane equation.

3. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 2 is characterized in that: The slope K of the i-th reflector i for: The width of the i-th reflector is L i for: The coordinates of the i-th mirror are: Among them, β i is the inclination angle of the i-th reflector, W is the width of the photovoltaic panel, X Mi and X Ni Respectively represent the starting point M of the i-th reflector i and end point N i The horizontal axis of .

4. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 1 is characterized in that: The frequency division film is a multilayer film in which high refractive index materials and low refractive index materials are alternately stacked, and the high refractive index material serves as the surface layer.

5. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 4 is characterized in that: The multilayer film has 13 layers.

6. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 5 is characterized in that: The periodic structure film system of the frequency division film is: Air / (aH bL)^m / Sub Among them, Air represents the sunlight incident on the air, H is the high refractive index material TiO2, L is the low refractive index material SiO2, a is the thickness of the TiO2 film layer, b is the thickness of the SiO2 film layer, m is the number of periodic film layers, and Sub is the metal substrate Al.

7. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 4 is characterized in that: The spectral reflectivity ρ and spectral transmittance τ of the frequency division film are: Where λ is the wavelength of solar radiation.

8. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 6 is characterized in that: Photovoltaic panels are monocrystalline silicon cells.

9. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 8 is characterized in that: An aluminum mirror is added to the bottom of the photovoltaic panel to reflect the solar radiation transmitted by the frequency-splitting film back to the photovoltaic panel.

10. The photovoltaic and thermal comprehensive utilization system based on the optimization of the tower type solar thermal power station according to claim 1, characterized in that: A reflector is installed under the collector to reflect the sunlight that is not absorbed by the collector for a second time and re-focus it on the collector.

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