Reflector for solar power generation system

Abstract

The present application improves power generation efficiency, reduces site area, and increases power generation while reducing construction, maintenance, and other costs. Also provided is a reflector for a solar power generation system that has excellent weather resistance. A reflector for a solar power generation system having solar power generation panels (2) that are disposed in a manner in which the power generation surfaces (6) of the upper surfaces are inclined at a prescribed angle by a stand (3) toward the direction of sunlight incidence, the reflector (4) being composed of: a reflection layer (14) having a light reflection surface formed of a thin sheet material of a color having a high light reflectance for reflecting direct light and scattered light of sunlight toward the lower surface power generation surface (12) of the solar power generation panel (2); and a weed-preventing layer (15) formed of a weed-preventing thin sheet material, the reflection layer (14) and the weed-preventing layer (15) being formed in a stacked manner in one body, the thickness of the reflector (4) being 1.0 mm or more.

Description

Technical Field

[0001] This invention relates to a reflector for a solar power generation system. Background Technology

[0002] Previously, as a solar power generation system, there were systems called mega-solar power plants that arranged a large number of solar panels on the ground to generate electricity on a large scale.

[0003] As shown in Patent Documents 1 and 2 below, this megawatt-class solar power plant involves setting up a large number of solar panels on a vast site, with each solar panel configured on a platform at a predetermined angle.

[0004] This type of solar power system, consisting of a large number of solar panels, is installed in a large outdoor area, thus requiring a great deal of work to maintain, such as suppressing the growth of weeds from the ground surface under the solar panels to prevent a decrease in power generation efficiency.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-228736

[0008] Patent Document 2: Japanese Patent Application Publication No. 2015-216766

[0009] Patent document 3: Japanese Patent Application Publication No. 2019-068795. Summary of the Invention

[0010] The problem the invention aims to solve

[0011] As mentioned above, the weeds growing on the site surface can obstruct the solar panels, reducing the amount of sunlight reaching the panels. Weed removal, whether by manual pulling or applying herbicides (requiring workers), is extremely time-consuming. Furthermore, since weeds cannot be easily eradicated and will regrow, multiple weeding operations are necessary, making maintenance very complex. Additionally, the use of herbicides carries the risk of damaging the surrounding natural environment. To mitigate this, methods such as covering the site surface with concrete after weeding or laying weed-control sheets on the ground have been explored, but these are all complex operations, and cost reduction is sought.

[0012] On the other hand, it is necessary to install a large number of solar panels on a large site to ensure sufficient power generation. To install a large-scale power generation facility with an output of 1 MW (1 megawatt = 1000 kW) or more, a flat area is required. Therefore, efforts are being made to explore installation methods that achieve, for example, high power generation efficiency per unit area of ​​the site. To improve such efficiency, methods exist that use reflective multilayer sheets, as described in Patent Document 3, laid on the ground and solar panels with power generation capabilities on the back side to utilize reflected light from the ground for power generation. However, while these methods suppress weed growth, they only prevent sunlight from reaching the weeds and do not eliminate the need for weed removal or uprooting, requiring maintenance costs. Further improvements are desired. Furthermore, the surface side of the reflective multilayer sheet is made of a resin film, so when installed on uneven ground, the reflective surface of the sheet becomes uneven, resulting in reduced reflectivity and a risk of reduced light incident on the back side of the solar panel. Additionally, there is a risk of sheet breakage when installed on uneven ground.

[0013] The present invention was made in view of the above-mentioned situation, and its object is to provide a reflector for a solar power generation system that improves power generation efficiency, reduces site area, and increases power generation while reducing construction and maintenance costs. Furthermore, it aims to provide a reflector for a solar power generation system with excellent weather resistance.

[0014] Solution for solving the problem

[0015] Next, a solution for solving the above-mentioned problems will be described with reference to the accompanying drawings corresponding to the implementation method.

[0016] The reflector 4 used in the solar power generation system with a double-sided incident solar panel 2 as described in claim 1 of this invention is characterized in that: Multiple solar panels 2 are arranged such that the upper surface of the power generation surface 6 is tilted at a predetermined angle toward the direction of sunlight incident by means of a mounting 3; the reflector for the solar power generation system is characterized in that:

[0017] The reflector 4 is composed of the following:

[0018] The reflective layer 14 has a light-reflecting surface formed of a thin sheet material of a high light reflectivity that reflects both direct and diffuse sunlight toward the lower surface of the solar panel 2, the power-generating surface 12; and

[0019] Weed control layer 15 formed of weed control sheet material,

[0020] The reflective layer 14 and the weed-control layer 15 are formed as a single unit by being stacked together.

[0021] The thickness of the reflector 4 is 1.0 mm or more.

[0022] In this solar power generation system, the reflector 4, made of a thin sheet material with high light reflectivity, reflects both direct and scattered sunlight onto the power generation surface 12 on the lower surface of the double-sided incident solar panel 2, thereby improving power generation efficiency. Furthermore, by incorporating a weed-control layer 15 into the reflector 4, weeds growing from the site surface are suppressed, thereby reducing maintenance work and its costs.

[0023] Furthermore, according to the reflector 4, even when it is set on an uneven ground, the reflectivity is not reduced because the reflective surface becomes a flat surface or a near-flat surface with a slight slope, and the light incident on the lower surface of the solar panel 12 is not reduced.

[0024] The reflector for a solar power generation system according to claim 1, and the reflector for a solar power generation system according to claim 2 of the present invention, are characterized in that,

[0025] The light-reflecting surface is white.

[0026] In the reflector of this solar power generation system, by making the light-reflecting surface white, the wavelength of light used for power generation from direct sunlight and scattered sunlight can be well incident as reflected light onto the lower surface power generation surface 12, thereby improving power generation efficiency.

[0027] The reflector for a solar power generation system according to claim 1, and the reflector for a solar power generation system according to claim 3 of the present invention, are characterized in that,

[0028] The light-reflecting surface is formed of a metal layer.

[0029] In the reflector of this solar power generation system, by making the light reflecting surface a metal layer, direct and scattered sunlight can be well incident on the lower surface power generation surface 12 as reflected light, thereby improving power generation efficiency.

[0030] The reflector for a solar power generation system according to any one of claims 1 to 3, and the reflector for a solar power generation system according to claim 4 of the present invention, are characterized in that,

[0031] The light reflector has a reflectivity of over 70% for light with wavelengths of 500nm to 1000nm in sunlight, and an average reflectivity of less than 15% for light with wavelengths of 5000nm to 20000nm.

[0032] In the reflector of this solar power generation system, the near-infrared region of visible light (short wavelength side) is reflected, while the far-infrared region has low reflectivity. Therefore, the temperature of the solar panel can be prevented from rising, and the power generation efficiency will not be reduced.

[0033] The reflector for a solar power generation system according to any one of claims 1 to 4, and the reflector for a solar power generation system according to claim 5 of the present invention, are characterized in that,

[0034] The front surface of the reflective layer constituting the reflector 4 is water-resistant, and the water-resistant coefficient of the reflector 4 is set to 1.0 × 10⁻⁶. -11 Below m / sec.

[0035] In this solar power generation system, the reflector layer 14, which is laid on the surface of the site, has water-resistant properties on its front side, thus preventing rainwater from lingering on the front of the reflector 4 and guiding it to the outside of the reflector. This makes the front side of the reflector layer 14 less prone to contamination and reduces the frequency of maintenance.

[0036] The reflector for a solar power generation system according to any one of claims 1 to 4, and the reflector for a solar power generation system according to claim 6 of the present invention, are characterized in that,

[0037] The reflector 4 is permeable to water, and its permeability coefficient is set to 1.0 × 10⁻⁶. -5 m / sec~1.0m / sec.

[0038] In this solar power generation system, the reflector 4, which is laid on the site surface, is permeable, allowing rainwater to pass through and be guided to the site surface, preventing rainwater from remaining on the front of the reflector 4. Therefore, the power generation efficiency is not reduced.

[0039] The reflector for a solar power generation system according to any one of claims 1 to 6, and the reflector for a solar power generation system according to claim 7 of the present invention, are characterized in that,

[0040] The front side of the reflective layer has an ultraviolet degradation prevention layer.

[0041] In the reflector of this solar power generation system, ultraviolet degradation can be prevented by an anti-ultraviolet layer, which can prevent degradation caused by the ultraviolet light contained in sunlight, thus extending the life of the reflector and extending the replacement and maintenance intervals.

[0042] The reflector for a solar power generation system according to claim 2, and the reflector for a solar power generation system according to claim 8 of the present invention, are characterized in that,

[0043] The reflective layer is composed of thermoplastic resin and white pigment.

[0044] In the reflector of this solar power generation system, the light-reflecting layer is made white, which allows the light of the wavelength used for power generation from direct sunlight and scattered sunlight to be well incident on the lower power generation surface as reflected light, thereby improving power generation efficiency.

[0045] Furthermore, even when installed on uneven ground, the reflectivity is not reduced because the reflective surface of the sheet is flat, and the amount of light incident on the back of the solar panel is not reduced.

[0046] The reflector for a solar power generation system according to claim 8, and the reflector for a solar power generation system according to claim 9 of the present invention, are characterized in that,

[0047] The thermoplastic resin is composed of olefin-based resin.

[0048] In the reflector used in this solar power generation system, the reflective layer becomes a structure with excellent mechanical strength.

[0049] The reflector for a solar power generation system according to claim 9, and the reflector for a solar power generation system according to claim 10 of the present invention, are characterized in that,

[0050] The olefin-based resin is composed of at least one of low-density polyethylene and linear low-density polyethylene.

[0051] In the reflector of this solar power generation system, the structure of the reflective layer can be designed to be excellent in terms of flexibility and workability even in ethylene-based resin sheets.

[0052] The reflector for a solar power generation system according to claim 2, and the reflector for a solar power generation system according to claim 11 of the present invention, are characterized in that,

[0053] The weed control layer is composed of thermoplastic resin and black pigment.

[0054] In the reflector of this solar power generation system, the weed control layer is made of black sheet material, which has a higher density than non-woven fabric, and can efficiently apply weight pressure per unit volume to the weeds, causing them to wither and die.

[0055] The reflector for a solar power generation system according to claim 11, and the reflector for a solar power generation system according to claim 12 of the present invention, are characterized in that,

[0056] The thermoplastic resin is composed of olefin-based resin.

[0057] In the reflector used in this solar power generation system, the weed control layer is a structure with excellent mechanical strength.

[0058] The reflector for a solar power generation system according to claim 12, and the reflector for a solar power generation system according to claim 13 of the present invention, are characterized in that,

[0059] The olefin-based resin is composed of at least one of low-density polyethylene and linear low-density polyethylene.

[0060] In the reflector of this solar power generation system, the structure of the weed control layer can be designed to be excellent in terms of flexibility and workability, even in ethylene-based resin sheets.

[0061] The effects of the invention

[0062] According to the solar power generation system reflector described in claim 1 of the present invention, for the power generation surface of the lower surface of a double-sided incident solar power panel, a reflector made of a thin sheet material with high light reflectivity is used to reflect both direct and scattered sunlight onto the power generation surface, thereby improving power generation efficiency and increasing power generation. Furthermore, due to the increased power generation, the number of solar power panels required can be reduced, thus promoting the reduction of site surface area.

[0063] In addition, by having a weed-proof layer that contacts the field surface on the reflector, weeds can be suppressed from growing on the field surface, thereby reducing maintenance work such as weed removal and reducing maintenance costs.

[0064] Furthermore, according to this reflector, even when installed on uneven ground, the reflectivity is not reduced because the reflective surface becomes a flat or nearly flat surface with a slight slope, and the light incident on the lower surface of the solar panel is not reduced.

[0065] According to claim 2 of the present invention, the reflector for a solar power generation system is configured to be white, thereby enabling light of the wavelength used for power generation in direct sunlight and scattered sunlight to be well incident on the lower surface power generation surface as reflected light, thereby improving power generation efficiency.

[0066] According to claim 3 of the present invention, the reflector for a solar power generation system is made of a metal layer, thereby enabling direct and scattered sunlight to be reflected onto the lower surface of the power generation surface, thus improving power generation efficiency.

[0067] According to claim 4 of the present invention, the reflector for a solar power generation system reflects light in the near-infrared region (visible light - short wavelength side) of sunlight and has a low reflectivity in the far-infrared region, thereby preventing the temperature of the solar power panel from rising and achieving the effect of not reducing power generation efficiency.

[0068] According to claim 5 of the present invention, the reflector for a solar power generation system has water-resistant properties on the front side of the reflector, so that rainwater does not stay on the front side of the reflector but is guided to the outside of the reflector, thereby making the front side of the reflective layer less susceptible to contamination and reducing the frequency of maintenance.

[0069] According to claim 6 of the present invention, the reflector for a solar power generation system is permeable, allowing rainwater to pass through and be guided to the surface of the site, thus preventing rainwater from remaining on the front of the reflector. This achieves the effect of not reducing power generation efficiency.

[0070] According to claim 7 of the present invention, the reflector for a solar power generation system can prevent ultraviolet degradation of the reflector layer by means of an ultraviolet degradation prevention layer, that is, it can prevent degradation caused by the irradiation of light from the ultraviolet region contained in sunlight, thereby extending the life of the reflector and extending the replacement and maintenance intervals.

[0071] According to claim 8 of the present invention, the reflector for a solar power generation system is configured such that the light-reflecting layer is white, which enables light of the wavelength used for power generation in direct sunlight and scattered sunlight to be well incident as reflected light onto the lower surface power generation surface, thereby improving power generation efficiency.

[0072] According to claim 9 of the present invention, the reflector for a solar power generation system has a reflective layer that has excellent mechanical strength.

[0073] According to the reflector for a solar power generation system as described in claim 10 of the present invention, the structure of the reflective layer can be configured to have excellent flexibility and workability even in a ethylene resin sheet.

[0074] According to the reflector for a solar power generation system as described in claim 11 of the present invention, by making the weed-control layer composed of a black sheet, the density can be greater than that of non-woven fabric, thereby efficiently applying weight pressure per unit volume to the weeds and causing them to wither and die.

[0075] According to the reflector for a solar power generation system as described in claim 12 of the present invention, the weed control layer has a structure with excellent mechanical strength.

[0076] According to the reflector for a solar power generation system as described in claim 13 of the present invention, the structure of the weed control layer can be configured to be excellent in terms of flexibility and workability even in ethylene-based resin sheets. Attached Figure Description

[0077] Figure 1 This is a schematic perspective view of a solar power generation system according to the first embodiment of the present invention.

[0078] Figure 2 This is a schematic perspective view of a solar power generation system according to the second embodiment of the present invention.

[0079] Figure 3 This is a partially enlarged side view of a solar power generation system.

[0080] Figure 4 This is a partially enlarged summary side view illustrating the function of a solar power generation system.

[0081] Figure 5 This is a line graph showing the experimental results of a spectrophotometric reflectance measurement in an example of a reflective sheet, i.e., the relationship between wavelength and light reflectance. Detailed Implementation

[0082] The first embodiment of the present invention will now be described with reference to the accompanying drawings.

[0083] Figure 1 This is a perspective view showing an embodiment of a solar power generation system according to the present invention.

[0084] The solar power generation system 1 of this embodiment has a solar power generation panel 2, a mounting platform 3, and a reflector 4 as its main structures.

[0085] The solar panel 2 is constructed by integrating and modularizing multiple solar cell units. In this embodiment, it is a double-sided incident solar panel with solar cell units on both the front and back sides and two surfaces for generating electricity.

[0086] like Figure 1 As shown, multiple solar panels 2 are arranged horizontally and vertically, and connected laterally to form a long structure. They are mounted on a support 3 (described later) to form a solar cell array 5, which is arranged in multiple rows along a desired large site. These rows of solar cell arrays constitute a so-called megawatt-class solar power plant (large-scale solar power generation), i.e., a group of solar panels capable of generating at least 1 MW of output.

[0087] Each solar cell array 5 is arranged at a predetermined interval. This interval is designed such that the upper surface of the solar power generation surface 6 of each solar cell array 5 arranged in multiple rows does not cast shadows on each other from direct sunlight, and that workers can pass through sufficiently during maintenance and other times.

[0088] While there are various structures of solar panels, preferred options include the Swan series manufactured by Jinko Solar, the MBB bifacial PERC half-cell double-glass module manufactured by JA Solar, the Duomax Twin manufactured by Trina Solar, the HiKu5 series manufactured by Canadian Solar, the LR4-72HBD series manufactured by LONGi Solar, the Q.PEAK DUO manufactured by Hanwha Q CELLS, the double-glass bifacial monocrystalline PERC module manufactured by Risen Energy, and the GCL-M6 / 72GD manufactured by Golden Concord Holdings Limited (GCL). These panels all increase the power generation of each panel by approximately 20% by utilizing the lower surface power generation surface 12 on the back side.

[0089] Figure 3 This is a partially enlarged side view of a solar power generation system.

[0090] The solar cell array 5 consists of the aforementioned solar power panel 2 and a platform 3 on which the solar panel 2 is mounted, and is disposed on the site surface 7.

[0091] The platform 3 is composed of support columns 8, crossbeams 9, and connecting brackets 10, which are connected and fixed by means of screws, welding, etc. In addition, the platform 3 is fixed by a base 11 set on the ground 7.

[0092] The mounting platform 3 uses connecting brackets 10 to fix the solar panel 2, and sets the power generation surface of the solar panel 2 to be tilted from the horizontal at, for example, about 30°. This tilt angle is determined based on the latitude, environment and other conditions of the installation site. For example, in high-latitude regions of the Northern Hemisphere such as Japan, the upper surface power generation surface 6 is fixed to the mounting platform 3 in a way that tilts southward.

[0093] The height of the mounting platform 3 is set such that the height from the site surface 7 to the lower edge 2a of the inclined panel 2 is more than 0.8m, ensuring sufficient space at the bottom of the mounting platform 3. This space becomes the light transmission space 13 for the lower surface power generation surface 12 of the solar panel 2.

[0094] The reflector 4 is located on the lower part of the platform 3 and is disposed on the ground surface 7 in a manner that faces the lower surface of the solar panel 2, which is the power generation surface 12.

[0095] The reflector 4 is in the form of a thin sheet, consisting of a reflective layer 14 as the upper surface and a weed-proof layer 15 as the lower surface, forming a stacked structure obtained by integrating these layers.

[0096] In the first embodiment, the front side of the reflective layer 14 constituting the reflector 4 is water-resistant.

[0097] The reflective layer 14 is formed of a thin sheet material with high light reflectivity that reflects light of the wavelength used for power generation from both direct and scattered sunlight. In this embodiment, the reflective sheet is configured to be white on the front side. This reflective sheet is formed of a soft material such as a resin sheet or rubber sheet with a thickness of 0.5 mm to 3.0 mm, preferably 1.0 mm or 1.5 mm. For example, the resin sheet material may be polyethylene resin, polyester resin, polypropylene resin, polyethylene terephthalate resin, vinyl chloride resin, polystyrene resin, fluoropolymer resin, nylon resin, etc. Furthermore, the front side is set to white, either as the white material of the reflective sheet itself or as a coating that makes the front side white.

[0098] The reflective sheet with this water-blocking property has a water-blocking coefficient of 1.0 × 10⁻⁶. -11 With a flow rate of m / sec or less, it can effectively guide rainwater and water droplets from the front to the outside. Here, "water-blocking coefficient" refers to the "permeability coefficient" in the voluntary standard for water-blocking sheets stipulated by the Japan Water-Blocking Engineering Association. However, in this invention, there is a risk of confusion with the permeability coefficient described later, so it is referred to as "water-blocking coefficient". This water-blocking coefficient is obtained by calculating the permeability according to JIS Z 0208 "Test Method for Moisture Permeability of Moisture-Proof Packaging Materials (Cup Method)" and then using the calculation formula described in "6.4.8 Calculation of Permeability Coefficient" in the "Guidelines for the Management of Water-Blocking Engineering Technology" (issued by the Japan Water-Blocking Engineering Association; May 2019 edition). According to the above values, low permeability means high water-blocking performance.

[0099] The front side of the reflective sheet is preferably waterproof, thus repelling rainwater and allowing water droplets to be easily guided from the front to the outside. Additionally, the reflective sheet preferably possesses properties such as chemical resistance, heat resistance, fire and heat protection, non-flammability, cold resistance, radiation resistance, thermal conductivity, abrasion resistance, friction resistance, and anti-static properties. Furthermore, a transparent protective layer can also be provided on the front side. The structure of a waterproof reflective sheet is as follows. For example, the first method is to add a waterproofing agent to the reflective sheet. The second method is to apply a surface treatment agent made from the waterproofing agent to the surface of the reflective sheet.

[0100] Regarding the point that the front of the aforementioned reflective sheet is white with high light reflectivity, more specifically, although the power-generating surface of the solar panel 2 generates electricity by being irradiated by sunlight, it is not necessary for the power-generating surface to receive the full wavelength range of sunlight; therefore, the infrared region is not required. On the other hand, sunlight in the infrared region causes heat generation in the solar panel 2, and reduces power generation efficiency when the power-generating surface exceeds 50°C.

[0101] Therefore, it is preferable to reflect the near-infrared region of the visible light to short wavelength side of sunlight on the front side of the reflective sheet. For example, the front side of the reflective sheet is made white, and an infrared removal film is provided on the front side. For example, a film such as a filter that removes or absorbs near-infrared and far-infrared rays in the region above 1000nm is provided, and the structure is designed to prevent infrared light from being reflected to the solar panel 2.

[0102] In addition, since reflective sheets are easily degraded by ultraviolet rays contained in sunlight, an ultraviolet degradation prevention layer can be formed by combining an ultraviolet absorber with the surface of the reflective sheet or by applying an ultraviolet degradation prevention coating.

[0103] Furthermore, as described above, the reflective sheet preferably has the following characteristics: a reflectivity of 70% or more for light with wavelengths of 500 nm to 1000 nm in sunlight and a low reflectivity for light with wavelengths of 2300 nm or more; and an average reflectivity of 15% or less for wavelengths of 5000 nm to 20000 nm; preferably, an average reflectivity of 10% or less for wavelengths of 5000 nm to 20000 nm; and does not reflect light in the range of short-wavelength infrared to mid-wavelength infrared and long-wavelength infrared (thermal infrared), which is referred to as far-infrared. In addition, for example, the structure can be configured such that the front side of the reflective sheet is white and an infrared removal film is provided on the front side, preferably a film such as a filter that removes or absorbs near-infrared and far-infrared rays in the region of 1000 nm or more, so as not to reflect infrared light to the solar panel 2.

[0104] As a specific reflective sheet, a preferred example is mLLDPE / MLPSLS (Japanese: ビノンメタロバリアー) manufactured by TAKIRON-CI. Co., Ltd. (trade name), which is made of an olefin-based resin consisting of a white layer with white pigment on the front and a black layer with black pigment on the back. In this case, the reflective sheet itself has a light-blocking rate of about 99%, and weed-repelling effect can also be expected.

[0105] The following shows the experimental results of the spectrophotometric reflectance of the reflective sheet (mLLDPE / MLPSLS (trade name)) measured by a Fourier transform infrared spectrophotometer (FTIR) in accordance with JIS R 1693-2:2012.

[0106] [Experimental Apparatus]

[0107] • FTIR device (Perkin Elmer System2000 model)

[0108] • The integrating sphere (RSA-PE-200-ID manufactured by Labsphere) has a gold-coated interior.

[0109] • Integrating sphere incident diameter: ϕ16mm

[0110] • Measuring section diameter: ϕ24mm.

[0111] [Measurement Conditions]

[0112] • Measurement area: 370cm -1 ~7800cm -1 (Effective range 400cm) -1 ~6000cm -1 )

[0113] Total number of times: 200

[0114] • Light source: MIR

[0115] • Detector MIR-TGS

[0116] • Resolution: 16cm -1

[0117] • Beam splitter: Optimized KBR

[0118] • Purge the light path from the light source to the detector by filling it with N2 gas.

[0119] [condition]

[0120] • The reflectance spectrum was measured at room temperature.

[0121] Furthermore, the use of the integrating ball shall comply with JIS R 1693-2:2012.

[0122] [Measurement Results]

[0123] exist Figure 5 The spectrophotometric reflectance spectrum at room temperature is shown as a line graph representing the relationship between wavelength and reflectance. For example... Figure 5As shown, the following characteristics can be obtained: the average light reflectance for wavelengths of 5000nm to 20000nm is as low as 10% or less, and it does not reflect light in the range of short-wavelength infrared to mid-wavelength infrared, long-wavelength infrared (thermal infrared), and so-called far-infrared.

[0124] The weed control layer 15 is formed from a highly light-blocking weed control sheet, such as a non-woven fabric.

[0125] The weed control sheet forming the weed control layer 15 is a sheet material that causes weeds to die by applying environmental pressures such as thermal pressure, weight pressure, and pressure caused by hindering photosynthesis.

[0126] Regarding such weed-control sheets, specific materials include polyester fiber nonwoven fabric, polyethylene fiber, polyamide fiber, aramid fiber, acrylic fiber, carbon fiber, polyurethane fiber, cotton thread, wool thread, silk thread, hemp, and wool, etc., which are used to form the sheet either as a single material or in combination of two or more materials. Alternatively, a resin sheet that is not permeable to water can also be used for the weed-control sheet. When the reflector 4 is placed on an uneven surface, it is more preferable to use a highly cushioning woven fabric or nonwoven fabric to prevent damage to the reflective layer 14 due to unevenness in the ground.

[0127] As described above, the weed-control sheet is preferably made of non-woven fabric and is configured such that the light transmittance at each wavelength measured per 1 nm in the range of 400 nm to 700 nm is 10% or less, the puncture resistance is 10 N to 30 N, and the weight per unit area is 100 g / m². 2 ~400g / m 2 .

[0128] As a non-permeable resin sheet, it is formed from a soft material such as a resin sheet or rubber sheet with a thickness of 0.5 mm to 3.0 mm, preferably 1.0 mm or 1.5 mm. For example, the material used for the resin sheet is polyethylene resin, polyester resin, polypropylene resin, polyethylene terephthalate, vinyl chloride resin, polystyrene resin, fluororesin, nylon resin, etc.

[0129] As specific examples of weed control sheets, for instance, the following three types are listed as non-woven fabrics.

[0130] <Example 1>

[0131] For example, it is preferable to use AXTARmantle weed control sheets (trade name) manufactured by Toray Industries, Inc., which have the following characteristics: a mass of 150 g / m² per unit area. 2 ~260g / m 2 It has a thickness of 0.4mm to 0.6mm and a density of 0.4g / cm³.3 The tensile strength is 290 N / 5 cm to 790 N / 5 cm in the longitudinal direction and 190 N / 5 cm to 500 N / 5 cm in the transverse direction. The elongation is 15% to 30% in the longitudinal direction and 15% to 25% in the transverse direction. The tear strength is 80 N in the longitudinal direction and 100 N in the transverse direction. The water permeability coefficient is 8.0 × 10⁻⁶. -5 m / sec~1.0×10 -4 m / sec, puncture resistance of 17N~20N, and light blocking rate of 95%.

[0132] <Example 2>

[0133] Furthermore, this weed-control sheet is generally designed to block sunlight, i.e., have a light-blocking rate of 95% or higher. For example, it is preferable to use 9321N (trade name) manufactured by Toyobo Co., Ltd., which is made of a nonwoven fabric with a weight of approximately 310 g / m³. 2 The thickness is approximately 3.8 mm when pressed at 0.7 kPa and approximately 3.5 mm when pressed at 2 kPa. The tensile strength is approximately 1200 N / 5 cm in the longitudinal direction and approximately 920 N / 5 cm in the weft direction. The longitudinal elongation is approximately 70%, and the transverse elongation is approximately 80%. The tear strength is 250 N in the longitudinal direction and approximately 240 N in the transverse direction. The permeability coefficient at a water temperature of 15℃ is 4.4 × 10⁻⁶. -3 The speed is m / sec, and the fracture strength is approximately 3200 kPa.

[0134] <Example 3>

[0135] The following type of weed control sheet is preferred: weight per unit area is set at 2 kg / m². 2 The above applies weight pressure to the weeds, and the light transmittance of each wavelength measured per 1 nm in the range of wavelength above 400 nm and below 800 nm is less than 10%. It absorbs sunlight to inhibit the photosynthesis of weeds under the weed control sheet, and absorbs sunlight to increase the temperature of the weed control sheet itself, thus applying thermal pressure to the weeds under the weed control sheet.

[0136] Furthermore, the reflective sheet serving as the reflective layer 14 is set as the front side and the weed-control sheet serving as the weed-control layer 15 is set as the back side, and the sheet-like reflector 4 is obtained in a stacked structure.

[0137] As an integrated reflective sheet and weed-control sheet, the reflective body 4 can be obtained by a process of co-extruding the two sheets into a two-layer integral structure using an extrusion molding device, or by laminating the reflective sheet and the weed-control sheet together using a lamination device. Furthermore, the reflective body 4 can also be obtained by hot-pressing the reflective sheet and the weed-control sheet together using a hot-pressing device, or by bonding the reflective sheet and the weed-control sheet together using an adhesive, such as by surface bonding, dot bonding, or line bonding.

[0138] The thin reflector 4 is formed, for example, with a width of 1.0m to 2.5m and a length of 10m to 100m, and is manufactured, stored, and transported in a rolled-up state. Moreover, when laying the reflector 4, the reflector 4 is rolled back from the rolled-up state, unfolded on the field surface 7, and multiple reflectors are arranged in the width direction and connected to each other for fixation, thereby achieving seamless coverage of the field surface 7.

[0139] Next, refer to Figure 2 The second embodiment of the present invention will be described below.

[0140] Figure 2 This is a schematic perspective view of a solar power generation system according to the second embodiment of the present invention.

[0141] In the second embodiment, the solar panel 2 and the mounting platform 3 can use the same solar panel and mounting platform as in the first embodiment.

[0142] In the second embodiment, the reflective layer 14 constituting the reflector 4 is water-permeable.

[0143] The reflective layer 14 is permeable, allowing rainwater to quickly penetrate to the surface of the site. For such a permeable reflective sheet, a structure with numerous perforations 16 is formed through it, using woven or non-woven fabric, or a water-resistant resin or rubber sheet. By forming the perforations 16, the reflective sheet becomes permeable in its thickness direction. The perforations 16 are through holes with a good water-carrying inner diameter, formed partially or entirely on the surface.

[0144] The reflective layer 14 is formed of a thin sheet material of a color with high light reflectivity that reflects light of the wavelengths used to generate electricity from direct sunlight and scattered sunlight.

[0145] As specific materials for nonwoven fabrics, polyester fiber and other long fiber nonwoven fabrics, polyethylene fiber, polyamide fiber, aramid fiber, acrylic fiber, carbon fiber, polyurethane fiber, cotton thread, wool thread, silk thread, hemp, wool, etc. are used as materials, and they are used to form a single or combined two or more materials.

[0146] Furthermore, it is preferably set that the light transmittance at each wavelength measured per 1 nm in the range of wavelength above 400 nm and below 700 nm is less than 10%, the puncture resistance is 10 N to 30 N, and the unit area weight is 100 g / m². 2 ~400g / m 2 .

[0147] The water-resistant sheet having the perforated portion 16 described above is formed from a soft material such as a resin sheet or a rubber sheet with a thickness of 0.5 mm to 3.0 mm, preferably 1.0 mm or 1.5 mm. For example, the material for the resin sheet is polyethylene resin, polyester resin, polypropylene resin, polyethylene terephthalate, vinyl chloride resin, polystyrene resin, fluororesin, nylon resin, etc.

[0148] The weed control layer 15 preferably uses a highly light-blocking weed control sheet, such as a non-woven fabric.

[0149] As specific materials, polyester fiber nonwoven fabric, polyethylene fiber, polyamide fiber, aramid fiber, acrylic fiber, carbon fiber, polyurethane fiber, cotton thread, wool thread, silk thread, hemp, wool, etc. are used as materials, and they are used to form a single or combined two or more materials.

[0150] In addition to nonwoven fabrics, embossed three-dimensional structures such as sheets and nets can also be integrated with nonwoven fabrics as drainage core materials.

[0151] To achieve sufficient weed control, it is preferable that at least one layer constituting the weed-control layer is made of a dark color such as black for light-blocking purposes. However, if the reflective layer provides sufficient light-blocking, the weed-control sheet does not need to be light-blocking.

[0152] As specific examples of weed control sheets, for instance, the following three types are listed as non-woven fabrics.

[0153] <Example 1>

[0154] For example, it is preferable to use AXTARmantle weed control sheets (trade name) manufactured by Toray Industries, Inc., which have the following characteristics: a mass of 150 g / m² per unit area. 2 ~260g / m 2 It has a thickness of 0.4 mm to 0.6 mm and a density of 0.4 g / cm³. 3 The tensile strength is 290 N / 5 cm to 790 N / 5 cm in the longitudinal direction and 190 N / 5 cm to 500 N / 5 cm in the transverse direction. The elongation is 15% to 30% in the longitudinal direction and 15% to 25% in the transverse direction. The tear strength is 80 N in the longitudinal direction and 100 N in the transverse direction. The water permeability coefficient is 8.0 × 10⁻⁶. -5m / sec~1.0×10 -4 m / sec, puncture resistance of 17N~20N, and light blocking rate of 95%.

[0155] <Example 2>

[0156] Furthermore, this weed-control sheet is generally designed to block sunlight, i.e., have a light-blocking rate of 95% or higher. For example, it is preferable to use 9321N (trade name) manufactured by Toyobo Co., Ltd., which is made of a nonwoven fabric with a weight of approximately 310 g / m³. 2 The thickness is approximately 3.8 mm when pressed at 0.7 kPa and approximately 3.5 mm when pressed at 2 kPa. The tensile strength is approximately 1200 N / 5 cm in the longitudinal direction and approximately 920 N / 5 cm in the weft direction. The longitudinal elongation is approximately 70%, and the transverse elongation is approximately 80%. The tear strength is 250 N in the longitudinal direction and approximately 240 N in the transverse direction. The permeability coefficient at a water temperature of 15℃ is 4.4 × 10⁻⁶. -3 The speed is m / sec, and the fracture strength is approximately 3200 kPa.

[0157] <Example 3>

[0158] The following type of weed control sheet is preferred: weight per unit area is set at 2 kg / m². 2 The above applies weight pressure to the weeds, and the light transmittance of each wavelength measured per 1 nm in the range of wavelength above 400 nm and below 800 nm is less than 10%. It absorbs sunlight to inhibit the photosynthesis of weeds under the weed control sheet, and absorbs sunlight to increase the temperature of the weed control sheet itself, thus applying thermal pressure to the weeds under the weed control sheet.

[0159] Furthermore, the reflective sheet serving as the reflective layer 14 is set as the front side and the weed-control sheet serving as the weed-control layer 15 is set as the back side, and the sheet-like reflector 4 is obtained in a stacked structure.

[0160] As an integration of reflective sheet and weed control sheet, the reflective sheet and weed control sheet can also be integrated by using a laminating device for hot lamination, by using a hot pressing device to hot press the reflective sheet and weed control sheet together, by using adhesives to bond the reflective sheet and weed control sheet together in a whole surface, in a dotted or linear manner, or by using a needle punching method to achieve integration.

[0161] The thin reflector 4 is formed, for example, with a width of 1.0m to 2.5m and a length of 10m to 100m, and is manufactured, stored, and transported in a rolled-up state. Moreover, when laying the reflector 4, the reflector 4 is rolled back from the rolled-up state, unfolded on the field surface 7, and multiple reflectors are arranged in the width direction and connected to each other for fixation, thereby achieving seamless coverage of the field surface 7.

[0162] In this embodiment, the reflector 4 as a whole needs a certain degree of water permeability. The water permeability from the front to the back of the reflector 4 can be expressed as the water permeability coefficient, which is set to 1.0 × 10⁻⁶. -5 The permeability is between 1.0 m / sec and 1.0 m / sec, effectively guiding rainwater and other water to the area beneath the thin sheet. The permeability coefficient is preferably set to 5.0 × 10⁻⁶. -5 The permeability coefficient ranges from m / sec to 1.0 m / sec. If the permeability coefficient is above the lower limit, the effect of guiding rainwater beneath the sheet is improved. Conversely, if the permeability coefficient is below the upper limit, the weight pressure of the reflector is fully utilized, resulting in good weed control and cushioning against uneven ground surfaces. This permeability coefficient can be determined according to the method specified in JIS A 1218, "Test Method for Permeability of Soil".

[0163] In this reflector 4, a sheet material with excellent water-carrying capacity and chemical resistance can be used, which is constructed in layers by using a black embossed three-dimensional structured sheet as the drainage core material and a long-fiber spunbond nonwoven fabric as the protective material. Examples include geoflow sheet material manufactured by DAIPLA Corporation. Alternatively, a sheet constructed using a three-dimensional mesh structure with upper and lower nonwoven fabric clamps can also be used as the substrate.

[0164] Next, the third embodiment of the present invention will be described.

[0165] Furthermore, in this third embodiment, the same symbols are added to the components that are equivalent to the parts shown in the first embodiment, and reference is made to... Figure 1 Please provide an explanation.

[0166] Similar to the first embodiment described above, in this third embodiment, the reflector 4 is disposed on the ground surface 7 at the lower part of the stand 3, facing the power generation surface 12 of the lower surface of the solar panel 2.

[0167] The reflector 4 is a thin sheet, consisting of a reflective layer 14 as the upper surface and a weed-control layer 15 as the lower surface, and these layers form an integrated stacked structure.

[0168] The reflective layer 14 is made of a material with high light reflectivity, such as white, which reflects light of wavelengths used to generate electricity from direct and scattered sunlight. It is designed to be a reflective sheet made of soft materials such as resin sheets or rubber sheets.

[0169] In addition, the weed control layer 15 has water-resistant and light-blocking properties, and is made of, for example, black material. It is designed to be a weed control sheet made of soft materials such as resin sheets or rubber sheets.

[0170] Moreover, these reflective sheets and weed-proof sheets are integrated into a single sheet material in a stacked manner to form a reflector 4.

[0171] The thickness of the reflector 4 is set to 1.0mm~2.0mm, preferably 1.0mm~1.3mm, and the thickness of the reflective layer 14 is preferably about 0.4mm.

[0172] In this third embodiment, the front surface of the reflective layer 14 constituting the reflector 4 also has a water-resistant structure, and the water-resistant coefficient is set to 1.0 × 10⁻⁶. -11 With a speed of m / sec or less, it effectively guides rainwater and water droplets from the front to the outside. In addition, both the reflective layer 14 and the weed-proof layer 15 have light-blocking properties, thus achieving a weed-proof effect.

[0173] The resin material constituting the reflective layer 14 of this third embodiment is a material made by combining thermoplastic resin, olefin resin and white pigment in a specified weight percentage.

[0174] The thermoplastic resin is provided as an olefin resin, vinyl chloride resin, polyester resin, rubber, thermoplastic elastomer, polystyrene resin, fluororesin, nylon resin, etc., preferably an olefin resin, and more preferably low-density polyethylene or linear low-density polyethylene.

[0175] The olefin-based resins include ethylene-based resins such as low-density polyethylene, linear low-density polyethylene using a Ziegler catalyst, and linear low-density polyethylene using a metallocene catalyst, as well as propylene resins such as ethylene-vinyl acetate copolymers, homogeneous polypropylene, and random propylene copolymers. Particularly preferred are at least one type of linear low-density polyethylene using a metallocene catalyst.

[0176] The white pigments include titanium oxide, zirconium oxide, calcium carbonate, calcium sulfate, zinc oxide, barium sulfate, barium carbonate, silicon oxide, aluminum oxide, kaolin, clay, talc, mortar, aluminum hydroxide, magnesium carbonate, and white hollow resin latex, with titanium oxide being the preferred choice.

[0177] In addition to the aforementioned resin and pigment, the reflective layer 14 also contains weather-resistant agents, such as ultraviolet absorbers and light stabilizers.

[0178] The resin material constituting the weed control layer 15 is a material made by combining thermoplastic resin, olefin resin and black pigment in a specified weight percentage.

[0179] The thermoplastic resin and olefin resin are assumed to be the same as the resin material constituting the above-mentioned reflective layer 14.

[0180] As a black pigment, it is set as carbon black such as furnace black, lamp black, acetylene black, and channel black, metal pigments such as copper oxide and iron oxide, and organic pigments such as aniline black, with carbon black being the preferred type.

[0181] Furthermore, the reflective sheet that becomes the reflective layer 14 is positioned on the front, while the weed-control sheet that becomes the weed-control layer 15 is positioned on the back, thus forming an integrated, laminated structure to obtain a sheet-like reflector 4. The integrated reflector 4 is a sheet material with a white front and a black back.

[0182] As an integrated reflective sheet and weed-control sheet, the reflective body 4 can be obtained by using an extrusion molding device to co-extrude the two sheets into a single layer; or by using a laminating device to heat-laminate the reflective sheet and the weed-control sheet into a single unit. Alternatively, the reflective body 4 can be obtained by using a hot-pressing device to heat-press the reflective sheet and the weed-control sheet together, or by using an adhesive to bond the reflective sheet and the weed-control sheet together in a full-surface, dotted, or linear manner.

[0183] The thin reflector 4 is formed, for example, with a width of 1.0m to 2.5m and a length of 10m to 100m, and is manufactured, stored, and transported in a rolled-up state. Moreover, when laying the reflector 4, the reflector 4 is rolled back from the rolled-up state, unfolded on the field surface 7, and multiple reflectors are arranged in the width direction and connected to each other for fixation, thereby achieving seamless coverage of the field surface 7.

[0184] Alternatively, the weed control layer 15 can also be configured as a layered nonwoven fabric structure, similar to the first embodiment. In this case, it is preferable to use a nonwoven fabric with a weight of approximately 310 g / m³. 2 The thickness is approximately 3.8 mm when pressed at 0.7 kPa and approximately 3.5 mm when pressed at 2 kPa. The tensile strength is approximately 1200 N / 5 cm in the longitudinal direction and approximately 920 N / 5 cm in the weft direction. The longitudinal elongation is approximately 70%, and the transverse elongation is approximately 80%. The tear strength is 250 N in the longitudinal direction and approximately 240 N in the transverse direction. The permeability coefficient at a water temperature of 15℃ is 4.4 × 10⁻⁶. -3The bursting strength is approximately 3200 kPa. In the case of forming a weed control layer from this nonwoven fabric, similar to the first embodiment described above, the reflective layer 14 is the front side and the nonwoven fabric is the back side. As a bonding method, hot pressing, hot molding bonding, bonding with hot melt adhesive, ultrasonic bonding, high frequency bonding, etc. are used to bond and integrate them, thus obtaining a sheet-like reflector 4 as a laminated structure.

[0185] The third embodiment, namely the reflector, which is a thin sheet material formed by integrating the reflective sheet and the weed-proof sheet in a laminated manner, preferably has the following material properties.

[0186] The reflector preferably has a tear strength of 60N to 300N, more preferably 70N to 250N, and even more preferably 90N to 200N. By setting the tear strength to the lower limit or above, a reflector that is difficult to be damaged by impact can be obtained. By setting the tear strength to the upper limit or below, the reflector has flexibility, and even when placed on uneven ground, the reflective surface is flat or can be a near-flat surface with a slight slope.

[0187] Although the reflectors are used to form a welded joint by overlapping their ends in the width direction as described above, it is preferable that the shear strength of the joint between the reflectors is 70 N / cm or more and 400 N / cm or less. More preferably, it is 100 N / cm or more and 300 N / cm or less. By ensuring that the shear strength of the joint is above the lower limit, peeling of the sheet from the overlapping portion during construction is suppressed. Furthermore, by setting the shear strength of the joint to below the upper limit, the overlapping portion becomes flexible, and even when installed on uneven ground, the reflective surface is flat or can become a nearly flat surface with a slight slope.

[0188] The reflector preferably has a tensile strength of 140 N / cm or more and 1000 N / cm or less, more preferably 200 N / cm or more and 800 N / cm or less. By setting the tensile strength above the lower limit, the reflector has sufficient strength and excellent workability. In addition, by setting the tensile strength below the upper limit, the reflector has flexibility, and even when installed on uneven ground, the reflective surface is flat or can be a near-flat surface with a slight slope.

[0189] Furthermore, it is preferable that the tensile strength after prolonged use of the reflector, i.e., after long-term weathering, is between 100 N / cm and 1000 N / cm, more preferably between 200 N / cm and 800 N / cm. By ensuring that the tensile strength after long-term weathering is within the above range, the reflector possesses sufficient weather resistance, maintaining a balance between strength and flexibility over a long period, thereby reducing the frequency of replacement.

[0190] The reflector preferably has an elongation at tensile fracture of 300% to 1000%, more preferably 400% to 900%, and even more preferably 600% to 800%. By ensuring that the elongation at tensile fracture is above the lower limit, the reflector exhibits flexibility, allowing the reflective surface to remain flat or form a near-flat surface with a slight slope, even when installed on uneven ground. Furthermore, by ensuring that the tensile strength is below the upper limit, the reflector possesses sufficient strength and excellent workability.

[0191] Furthermore, it is preferable that the elongation at tensile fracture after prolonged use of the reflector, i.e., after long-term weathering, is 250% to 1000%, more preferably 400% to 900%. Even more preferably, it is 500% to 800%. By ensuring that the elongation at tensile fracture after long-term weathering is within the above range, the reflector possesses sufficient weather resistance, maintaining a balance between strength and flexibility over a long period, thus reducing the frequency of replacement.

[0192] The reflector preferably has a visible light reflectance of 55% or more after long-term use, i.e., after long-term weathering. More preferably, it has a visible light reflectance of 65% or more. Even more preferably, it has a visible light reflectance of 70% or more after long-term weathering. By setting the visible light reflectance after long-term weathering to the above values ​​or above, the reflector has sufficient weather resistance and can allow reflected light to be incident on the lower surface of the solar panel with good efficiency for a long time, thus maintaining power generation efficiency.

[0193] The reflector preferably has an infrared reflectance of 1% to 15% before and after use, i.e., before and after long-term weathering, and more preferably 3% to 10%. By ensuring that the infrared reflectance before and after long-term weathering is within the above range, it is possible to suppress the heating of the solar panel caused by light of infrared wavelengths and prevent a decrease in power generation efficiency.

[0194] The following describes an embodiment of the third implementation.

[0195] Furthermore, in the embodiments described below, the thermoplastic resin is simply referred to as PE1, the olefin resin as PE2, the white pigment as W-MB, the black pigment as B-MB, and the weathering agent as UV-MB, which respectively constitute the reflective layer 14 and the weed control layer 15.

[0196] [Combining agents]

[0197] The complexing agents used in the examples are as described below.

[0198] •PE1 = Melting point: 98ºC, MFR: 2.0g / 10min (JIS K 7210-1, temperature 190ºC, load capacity 2.16kg), density: 0.908g / cm³ 3 Metallocene linear low-density polyethylene

[0199] •PE2 = Melting point: 111ºC, MFR: 0.35g / 10min (JIS K 7210-1, temperature 190ºC, load capacity 2.16kg), density: 0.922g / cm³ 3 The low-density polyethylene produced by high-pressure process, as a material property item, has the following basic material properties: MFR 0.35 g / 10 min (JIS K 7210-1, temperature 190ºC, load capacity 2.16 kg) and density 0.922 g / cm³. 3 As for mechanical properties, the tensile breaking stress is 20 MPa, the tensile breaking elongation is 650%, and the tensile impact strength is 470 KJ / m. 2 It has a flexural stiffness of 225 MPa, a hardness of 55 D, and an environmental stress cracking resistance of 9 Hr. As for thermal properties, its Vicat softening temperature is set at 97 ºC and its melting temperature (DSC) at 111 ºC. It is characterized by being additive-free and having high strength.

[0200] • W-MB = Density: 2.5 g / cm³ 3 Polyethylene masterbatch containing 83% titanium dioxide

[0201] •UV-MB = Melting point: 110 ºC, Density: 0.995 g / cm³ 3 Polyethylene masterbatch containing 20 wt% hindered amine light stabilizer (dimethylsuccinic acid•1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethyl-4-piperidine heavy condensate)

[0202] •B-MB = Low-density polyethylene masterbatch containing 40% carbon black

[0203] [Manufacturing Process]

[0204] <Example 1>

[0205] As the reflective layer 14, PE1 is mixed at 59% by weight, PE2 at 27% by weight, W-MB at 9% by weight, and UV-MB at 5% by weight. As the weed control layer 15, PE1 is mixed at 75% by weight, PE2 at 19% by weight, and B-MB at 6% by weight. These are then fed into their respective extruders and co-extruded to produce a reflector with a reflective layer 14 of 0.40 mm and a weed control layer 15 of 0.74 mm, resulting in a total thickness of 1.14 mm.

[0206] <Example 2>

[0207] Following the same procedure as above, PE1 is set to 45% by weight, PE2 to 36% by weight, W-MB to 9% by weight, and UV-MB to 10% by weight, to manufacture a reflector with a reflective layer 14 of 0.40mm and a weed-proof layer 15 of 0.74mm, i.e., a total thickness of 1.14mm.

[0208] <Example 3>

[0209] Following the same procedure as above, PE1 is set to 73% by weight, PE2 to 18% by weight, W-MB to 9% by weight, and no UV-MB is added. The reflective layer 14 is 0.31mm thick, PE1 is set to 74% by weight, PE2 to 18% by weight, B-MB to 8% by weight, and the weed control layer 15 is 1.19mm thick, which is a reflector with a total thickness of 1.5mm.

[0210] The respective combinations of these embodiments are shown in Table 1.

[0211] Table 1

[0212]

[0213] [evaluate]

[0214] The reflectors of the three embodiments manufactured according to the above manufacturing process were evaluated based on the following criteria. The evaluation results are shown in Table 2.

[0215] <Test Item 1: Tear Strength>

[0216] Using the reflectors of each embodiment, the tear strength was determined according to "6.6 Tear Test" in "6. Test Methods for Water-Blocking Sheets Based on Synthetic Rubber and Rigid Resin" of the "Guidelines for Construction Management of Water-Blocking Engineering Technology" (published by Japan Water-Blocking Engineering Association: May 2019 edition).

[0217] <Test Item 2: Shear Strength at the Joints Between Thin Sheets>

[0218] Two reflectors manufactured in each embodiment were prepared. The ends of these two reflectors were overlapped with each other with a 120mm overlap width. Using a TWINNY type automatic welding machine manufactured by LEISTER, pressure was applied using rollers (with 15mm × 2 rows of pressing parts) while baking with hot air at 500 ºC to obtain a welded joint. The joint was then cooled to room temperature. Using strips of 250mm in length and 25mm in width cut along the overlap direction at the overlap location, samples according to each embodiment were measured. The maximum load-bearing capacity at fracture at a tensile speed of 200mm / min was determined.

[0219] The tensile strength is calculated as the shear strength at the joint between the sheets using the following formula.

[0220] Tensile strength (N / cm) = Maximum load-bearing capacity (N) ÷ Width of sample (cm)

[0221] <Test Item 3: Tensile Strength, Test Item 4: Elongation at Tensile Fracture>

[0222] Using the reflectors of each embodiment, the tensile strength and elongation at tensile fracture were determined according to "6.5 Tensile Test" of "6. Test Methods for Water-Blocking Sheets of Synthetic Rubber and Rigid Resin" in the "Guidelines for Construction Management of Water-Blocking Engineering Technology" (published by Japan Water-Blocking Engineering Association: May 2019 edition).

[0223] In addition, samples were taken before and after the exposure test (long-term weathering test) for separate measurements. The exposure test is described below.

[0224] Exposure test: The test was conducted using a solar weather measuring instrument (model: solar weather measuring instrument S80BBR) manufactured by SUGA Testing Machines Co., Ltd., under the following conditions, in accordance with JIS A 1415-1999 and JIS K 7350-4-1996.

[0225] • Test conditions

[0226] Blackboard temperature: 63±3 ºC

[0227] Relative humidity: 50±5%

[0228] Irradiance on the front of the sample: 255±10%w / m 2 (Wavelength range 300nm~700nm)

[0229] Water spray circulation: water spray for 18±0.5 minutes, water spray stops for 102±0.5 minutes.

[0230] Irradiation time: 3000 hours.

[0231] <Experiment Item 5: Visible Light (360nm~830nm) Reflectivity>

[0232] Samples obtained from the exposure tests conducted on the reflectors of each embodiment were cut into 20mm × 20mm pieces. The total reflectance of the reflective layer 14 in the wavelength range of 190nm to 2500nm was measured using an integrating sphere on a Hitachi High-Tech spectrophotometer (UH4150). The total reflectance in the wavelength range of 360nm to 830nm was averaged using alumina (Al2O3 white board) as a standard sample and taken as the visible light reflectance. Measurements were performed with N=3.

[0233] (Apparatus used for measuring visible light reflectance)

[0234] • Uses a Φ60mm integrating sphere with an inner surface coated with Teflon.

[0235] • Wavelength range: 109nm~2500nm

[0236] • Scan speed: 600 nm / min

[0237] • Slit width: 5nm

[0238] • Sampling interval: 5nm

[0239] • Measurement environment: Room temperature (25 ºC), atmospheric temperature...

[0240] • Machine used: Hitachi spectrophotometer: UH4150 (manufactured by Hitachi High Technology Corporation).

[0241] <Test Item 6: Infrared (3.2μm~19.8μm) Reflectivity>

[0242] Samples were obtained by cutting the reflectors of each embodiment into 20mm × 20mm pieces and the relative reflectance was measured using a Perkin Elmer (Japan) Fourier transform infrared spectrophotometer (Spotlight400) with a gold mirror as a standard. This determined the positive reflectance of the reflective layer in the wavelength range of 1.3μm to 20.0μm. The average positive reflectance in the infrared region of 3.2μm to 19.8μm was taken as the infrared reflectance. Measurements were performed with N=3. Furthermore, samples were taken before and after the aforementioned exposure test, and measurements were performed separately.

[0243] (A device for using infrared reflectivity)

[0244] • Relative reflectance measurement (positive reflectance measurement) using a gold mirror as the standard.

[0245] • Angle of incidence: 23 degrees

[0246] • Number of scans: 64

[0247] • Wavelength range: 1.3μm ~ 20.0μm (7800cm) -1 ~500cm -1 )

[0248] • Light source: MIR

[0249] • Detector: MCT

[0250] • Beam splitter: OptKBr

[0251] • Sampling interval: 2cm -1

[0252] • Measurement environment: Room temperature (20 ºC), atmospheric temperature...

[0253] • Machine used: FT-IR Spotlight400 (Perkin Elmer).

[0254] <Experiment Item 7: Appearance of the Reflective Layer>

[0255] The sample obtained by conducting the above-described exposure test on the reflectors of each embodiment was used, and the reflective layer 14 was observed under a microscope at 50x magnification to evaluate the occurrence of cracks and peeling.

[0256] ◎: No cracks were found

[0257] 〇: Cracks appeared but the reflective layer did not peel off.

[0258] ×: Numerous cracks were generated, and the reflective layer peeled off.

[0259] Table 2 shows the above evaluation results for the reflectors of each embodiment.

[0260] Table 2

[0261]

[0262] As a result of exposure, compared with Example 3 without the weathering agent (UV-MB), it can be seen that the tensile strength, elongation at tensile fracture, visible light reflectance, and infrared reflectance of the reflectors in Examples 1 and 2 with the weathering agent were not reduced, demonstrating excellent weather resistance. Furthermore, regarding visible light reflectance, after confirming the degradation acceleration after 3000 hours using magnified photographs, although cracks were confirmed in the front view of Example 3, no peeling of the reflective layer 14 occurred, and neither reflector presented any problems in use.

[0263] On the other hand, no significant cracks were observed in Examples 1 and 2, indicating that the weathering agent suppressed deterioration and reduced light reflectivity. Thus, a reflector 4 preferred for use in a solar power generation system was obtained.

[0264] Furthermore, in the structure of the reflector described above, although an example was given by setting the front side of the reflective sheet constituting the front side to white, a metallic layer can also be formed on the front side of the sheet material, which is a color with high reflectivity that reflects both direct and scattered sunlight. This reflective sheet with a metallic layer, when set as the front side, has a metallic sheen due to the metallic layer.

[0265] For example, it can also be configured as a reflective sheet with a metal foil, such as an aluminum foil, formed on the front side. In this reflective sheet with a metal foil, the substrate is, for example, the resin sheet described above, and a metal foil with a thickness of 0.5 mm to 1.0 mm is formed on the front side of one side of the substrate, i.e., the resin sheet.

[0266] Furthermore, when the material is a metal foil, since sunlight is totally reflected, infrared light is also reflected as described above, thus requiring heat countermeasures. In this case, to prevent glossy, mirror-like reflection and to achieve matte finish, it is preferable to apply a coating, create a rough surface by wrinkling the front side, or, similarly, incorporate a filter or coating that removes or absorbs infrared light.

[0267] In addition to metal foil, the structure can also be configured to coat a metal film onto a resin sheet, and the reflective surface can be formed by methods such as vapor deposition, coating, and electroplating.

[0268] Furthermore, in addition to aluminum as mentioned above, at least one light reflector selected from powders such as titanium dioxide, aluminum oxide, talc, calcium carbonate, zinc oxide, silicon dioxide, mica powder, glass powder, nickel powder, and aluminum powder can be formed into a film and constructed in shades ranging from silver to near white.

[0269] Alternatively, a transparent protective film can be formed on the front side of the aforementioned metal layer, etc., by coating. This protective film is formed, for example, from a resin material, such as polyethylene resin, and is configured as a coating, which is a preferred structure for providing waterproof and anti-fouling properties.

[0270] Next, the setup process of the solar power generation system 1 described above will be explained.

[0271] Furthermore, the process described below is a so-called renovation process in which a conventional solar power generation system has been constructed, is replaced with the solar power generation system 1 of the present invention, and its site and platform are reused.

[0272] First, weeding was carried out on the site. Weeds were growing under the solar panels and under the pedestals, so weeding and other removal operations were performed.

[0273] Next, remove the roots of the weeds. Weeds can regrow from their roots, so remove as much of the roots from the soil as possible. Alternatively, herbicides can be applied here.

[0274] Next, the reflector 4 is laid facing downwards towards the platform 3.

[0275] If the base 11 constituting the platform 3 is buried underground, a thin reflector 4 is installed corresponding to a portion of the base 11, and the reflector 4 is laid on the site surface 7 while avoiding the base 11. At this time, the reflector 4 covers the site surface 7 with the weed layer 15 facing down and the reflective layer 14 facing up, adhering as closely as possible. Furthermore, the reflector 4 is positioned approximately 2 meters beyond the portion where the platform 3 is installed and its outermost perimeter. Pin-shaped fasteners 17 are inserted through the reflector 4 at predetermined intervals to fix the reflector 4 to the ground. Alternatively, if the reflector 4 is in a rolled-up state as described above, it is laid while being rolled back, and fixed by bonding or welding to interlock in the width direction.

[0276] Next, the existing solar panels will be removed.

[0277] Remove the existing solar panels that are connected and fixed to the mounting platform 3 from the platform 3 and completely dismantle them. At this time, the electrical connections are also disconnected.

[0278] Next, the solar panel of this embodiment, namely the double-sided incident solar panel 2, is installed. Since the mounting platform 3 has already been assembled, the new solar panel 2 is placed on the mounting platform 3 and connected and fixed in sequence. At this time, if it is necessary to change the tilt angle, the angle is adjusted and fixed.

[0279] After that, the electrical connections of each solar panel 2 are made to complete the process.

[0280] Next, the function of the above structure will be explained.

[0281] In the solar power generation system 1 of this embodiment, the existing single-sided solar power generation panel is replaced with a double-sided incident type solar power generation panel 2, and a reflector 4 that reflects direct sunlight and scattered sunlight is laid on the surface 7 of the site, thereby increasing the power generation.

[0282] That is, in the case of existing solar power generation systems where the solar panels have only one side and each panel generates 250W, 4000 panels are needed to obtain 1000kW (1MW). However, in this embodiment, if each double-sided incident solar panel 2 can generate 320W of power, then by setting the same 4000 panels, 1280kW of power can be obtained. Compared with the rated output power, this is an increase of 1.28 times in power generation.

[0283] Therefore, in order to obtain the same 1000kW of power generation as before the replacement, in the case of the solar power generation system 1 in this embodiment, 3125 solar panels 2 can be used. That is, since each solar panel 2 is approximately the same size, the total area of ​​the solar panel 2 as a whole can be reduced by about 22%.

[0284] That is, during reconstruction, it becomes a solar power generation system 1 that can reduce the installation area and the number of solar panels 2 while achieving the same power generation as before, and can be constructed to obtain the same level of power generation by reducing the previous site.

[0285] The extent to which solar panels can convert actual sunlight energy into electrical energy, i.e., the proportion, is expressed as the conversion efficiency.

[0286] For example, a typical single-sided solar panel, such as the SANIX SRM296P-72N (hereinafter referred to as panel A), has a rated output of 296W and a conversion efficiency of 15.2%. A bifacial solar panel, such as the Trinasolar TSM-440DEG17M (hereinafter referred to as panel B), has a rated output of 440W and a conversion efficiency of 19.9%. Therefore, compared to panel A, panel B has a higher conversion efficiency on one side, with a higher efficiency per unit area (m²). 2 With high power generation, it is clear from the perspective of individual units that space-saving can be sought, which means that the cost of construction can be suppressed and reduced.

[0287] When comparing these solar panels (panels A and B mentioned above) to make their total output roughly equivalent, there are 18 panels A and 12 panels B. Panel A produces 5328W, while panel B produces 5280W. Although there is a 48W difference, when converting the actual output of panel A (2361W) to panel B for comparison, the output is 5280 ÷ 5328 × 2361 = 2339W. Comparing the output of panel A (2339W) with the actual output of panel B (3374W), the difference is 144.2% (3374 ÷ 2339).

[0288] In the case of plate B, which is a product that generates electricity from the back, the power generation efficiency is further improved by including the reflector 4 of the present invention, thus enabling further space saving and cost reduction.

[0289] Compared to solar panels that generate electricity from only one side, double-sided incident solar panels can increase power generation by about 30% to 50% by using both sides of the solar panel.

[0290] Therefore, as a solar power generation system 1, it can increase the revenue from the sale of generated electricity.

[0291] For example, with 3.5 hours of sunshine per sloping surface, the annual power generation per 1MW is 1,277,500 kWh on the top surface alone. When the FIT (Fixed Price Electricity Purchase) is set at 40 yen, the estimated revenue from electricity sales is 51,100,000 yen.

[0292] Furthermore, when the power generation of the solar power generation system 1 of the present invention, i.e., the system having power generation surfaces 6 and 12 on both sides and a reflector 4, increases by 30%, it generates 66,430,000 yen in electricity sales revenue, resulting in an annual revenue increase of 15,330,000 yen.

[0293] With the system's remaining 15-year electricity sales period, electricity sales will increase by approximately 230 million yen.

[0294] Figure 4 This is a partially enlarged summary side view illustrating the function of a solar power generation system.

[0295] In this embodiment of the solar power generation system 1, direct sunlight is incident on the power generation surface 6 of the upper surface of the double-sided incident solar panel 2. The direct sunlight reflected by the reflective layer 14 and the reflected light from the scattered sunlight are incident on the power generation surface 12 of the lower surface with high reflectivity. Power is generated through these two surfaces, 6 and 12. Light reflected from the reflector 4 placed under the platform 3 is effectively incident on the lower surface power generation surface 12 of the solar panel 2 via a predetermined distance through the space 13 and the surrounding ground surface 7 of the platform 3, thus causing the lower surface power generation surface 12 to generate electricity.

[0296] Therefore, the solar power generation system 1 according to this embodiment can increase the power generation compared to the past by means of the double-sided incident solar power generation panel 2, and is effective in obtaining as much power generation as possible in a limited site space, and can construct a solar power generation system 1 that takes into account the environment.

[0297] Furthermore, the reflector 4 of the solar power generation system 1 according to this embodiment suppresses the growth of weeds on the site surface 7 by means of the weed control layer 15, which can reduce the time and cost of maintenance such as the cost of removing weeds and personnel expenses. Since the weeds do not affect the power generation surface as they have in the past, the power generation will not be reduced, resulting in a significant cost reduction.

[0298] Furthermore, even if the reflector 4 in this embodiment is constructed using only a simple white weed-control sheet, it cannot adequately reflect both direct and diffuse sunlight, thus failing to generate sufficient power. Additionally, to achieve sufficient weed control, it must be a dark color such as black to effectively kill weeds. In other words, even using a single layer of weed-control sheet as a reflector cannot reflect an effective amount of sunlight. Therefore, a single layer of weed-control sheet cannot serve as the reflective layer of this invention. Moreover, a simple weed-control sheet is not a structure that sufficiently provides pollution protection, and considering maintenance, it cannot be used in a solar power generation system like that of this invention.

[0299] This invention is not limited to the above-described embodiments. Combining the various structures of the embodiments with each other, making changes and applications based on the description in the specification and well-known technologies by those skilled in the art are also contemplated by this invention and are included within the scope of protection.

[0300] For example, in the above structural example, although it describes the case of replacing an existing solar power generation system, i.e., a system composed of single-sided solar power generation panels, with the structure of the present invention, in the case of solar power generation system 1, it may also be a case of a new configuration.

[0301] In this case, construction can begin by laying the reflector 4 on the site surface 7, and the setup can be completed through the process of setting up the platform 3 and installing the double-sided incident solar panels 2.

[0302] At this time, for the set site 7, the required power generation is calculated, and the number of solar panels 2 can be calculated. The power generation of the solar power generation system 1 of the present invention is increased compared with the past, so the site area can be reduced for the configuration.

[0303] Furthermore, although the example uses a white front surface of the reflector 4, the color of the reflective layer 14 is not limited to the aforementioned colors. It can also be a light gray, a high-brightness color, a hue, etc., as long as it is a color that can reflect both direct and diffuse sunlight well, i.e., a color with high light reflectivity. For example, if it is a bright green, or a green-based color, hue, or a patterned color such as camouflage, it will reduce the sense of incongruity with the surrounding environment, such as trees, while also allowing for good reflection of both direct and diffuse sunlight, which is effective for the power generation surface 12 on the lower surface of the solar panel 2.

[0304] Furthermore, although an example is described in which the reflective sheet constituting the reflective layer 14 is made of a resin sheet as a substrate and a metal layer is formed on the front side, it is not limited to this as long as the light reflection is good. For example, it can be formed into a sheet shape as long as the fiber is impregnated with a gloss agent, the added fabric, warp yarns, weft yarns and glossy fibers are woven together, or a non-woven fabric using such fibers.

[0305] Therefore, the solar power generation system 1 according to this embodiment can increase power generation, reduce the site area, and reduce construction costs. In addition, maintenance costs can also be reduced due to weed suppression.

[0306] Explanation of symbols

[0307] 1: Solar power generation system; 2: Double-sided incident solar power panel (solar power generation panel); 3: Stand; 4: Reflector; 6: Upper surface power generation surface; 7: Site surface; 12: Lower surface power generation surface; 13: Light transmission space; 14: Reflective layer; 15: Weed control layer; 16: Perforated part.

Claims

1. A reflector used in a solar power generation system with a double-sided incident solar panel, wherein multiple solar panels are arranged such that the upper surface of the solar power generation panel is tilted at a predetermined angle toward the direction of sunlight incident by means of a mounting platform, and the reflector used in this solar power generation system is characterized in that... The reflector is composed of the following: A reflective layer having a light-reflecting surface formed of a thin sheet material of a high light reflectivity that reflects both direct and scattered sunlight toward the lower surface of the solar panel; and The weed control layer is formed of a thin sheet of weed control material. The reflective layer and the weed-control layer are formed as a single unit by being stacked together. The thickness of the reflector is 1.0 mm or more. The light reflector has a reflectivity of over 70% for light with wavelengths of 500nm to 1000nm in sunlight, and an infrared removal film is provided on the light reflector to remove or absorb near-infrared and far-infrared rays in the region above 1000nm, thus preventing infrared light from being reflected to the double-sided incident solar panel.

2. The reflector for a solar power generation system according to claim 1, characterized in that, The reflective layer is a polyethylene resin containing more than 0.01% by weight of weather-resistant agent.

3. The reflector for a solar power generation system according to claim 1, characterized in that, The light-reflecting surface is white.

4. The reflector for a solar power generation system according to claim 1, characterized in that, The light-reflecting surface is formed of a metal layer.

5. The reflector for a solar power generation system according to any one of claims 1 to 4, characterized in that, The average reflectivity of the light-reflecting surface at wavelengths of 5000nm to 20000nm is less than 15%.

6. The reflector for a solar power generation system according to any one of claims 1 to 4, characterized in that, The front side of the reflective layer constituting the reflector is water-resistant, and the water-resistant coefficient of the reflector is set to 1.0 × 10⁻⁶. - 11 Below m / sec.

7. The reflector for a solar power generation system according to any one of claims 1 to 4, characterized in that, The reflector is permeable to water, and its permeability coefficient is set to 1.0 × 10⁻⁶. -5 m / sec~1.0m / sec.

8. The reflector for a solar power generation system according to any one of claims 1 to 4, characterized in that, The front side of the reflective layer has an ultraviolet degradation prevention layer.

9. The reflector for a solar power generation system according to claim 3, characterized in that... The reflective layer is composed of thermoplastic resin and white pigment.

10. The reflector for a solar power generation system according to claim 9, characterized in that... The thermoplastic resin is composed of olefin-based resin.

11. The reflector for a solar power generation system according to claim 10, characterized in that... The olefin-based resin is composed of at least one of low-density polyethylene and linear low-density polyethylene.

12. The reflector for a solar power generation system according to claim 3, characterized in that... The weed control layer is composed of thermoplastic resin and black pigment.

13. The reflector for a solar power generation system according to claim 12, characterized in that... The thermoplastic resin is composed of olefin-based resin.

14. The reflector for a solar power generation system according to claim 13, characterized in that... The olefin-based resin is composed of at least one of low-density polyethylene and linear low-density polyethylene.

Images