Solar power generation panel unit

Abstract

To ensure that the necessary electricity can be obtained for extended periods, even on sunny days. [Solution] The present invention relates to a solar power generation panel unit 1, which comprises at least a module 10 having a plurality of cells for solar power generation and a light diffusion layer 13 disposed on one side in the thickness direction of the module 10, wherein the light diffusion layer 13 is a layer in which particles having a refractive index different from that of the translucent resin or glass plate material 23 and having a particle size that is mainly capable of forward scattering sunlight incident from the outside to the inside of the light diffusion layer 13 are mainly dispersed.

Description

Technical Field

[0001] The present invention relates to a panel unit for solar power generation.

Background Art

[0002] Recently, on a global scale, efforts to reduce the environmental load have been intensifying. One of such efforts is the conversion of power generation methods. The power share of thermal power generation using high-carbon sources (mainly coal and oil), hydroelectric power generation that leads to natural destruction, or nuclear power generation using nuclear substances with high radiation risks (uranium and plutonium) has been gradually decreasing. On the other hand, the power share of power generation using natural energy such as sunlight, solar heat, geothermal energy, and wind power has been gradually increasing.

[0003] Solar power generation, which is well-known as power generation using natural energy, is a power generation system that converts light energy from sunlight into electrical energy. Currently, solar power generation panels are widely used not only for commercial purposes but also for personal use. For example, such panels are installed not only on the slopes of mountains and hills but also on flat ground and even on the roofs and gardens of individual houses.

[0004] However, the current power generation efficiency of solar power generation is not particularly high compared to thermal power generation and nuclear power generation. For this reason, various improvements have been made to increase the power generation efficiency (for example, refer to Patent Documents 1 and 2). For example, Patent Document 1 discloses a method of interlockingly controlling the swinging of the upper-side power generation panel and the lower-side power generation panel so that the incident light angles of sunlight on both power generation panels become incident light angles with good power generation efficiency. Also, Patent Document 2 discloses a method of providing solar power generation panels on two or more surfaces of a plurality of polyhedrons, thereby irradiating sunlight incident from various angles onto the panels and improving the power generation efficiency.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The inventors have found that the duration of power supply from solar power generation is longer on cloudy days than on sunny days. Specifically, on sunny days, a large amount of power can be obtained around noon when sunlight strikes the solar panels almost perpendicularly, but the necessary power cannot be obtained in the morning and evening when sunlight strikes the panels at a large angle. On the other hand, on cloudy days, the necessary power can be obtained continuously from morning to evening. Such fluctuations in power output depending on the weather are undesirable, and improvement is needed in the market utilizing solar power generation.

[0007] This invention has been made in view of the above problems, and aims to enable the acquisition of necessary electricity for extended periods, even on sunny days. [Means for solving the problem]

[0008] (1) A solar power generation panel unit according to one embodiment for achieving the above objective is: A module equipped with multiple cells for solar power generation, A light-diffusing layer is disposed on one side in the thickness direction of the module, It has at least the following features: The light-diffusing layer is a layer in which particles having a different refractive index than the translucent resin or glass plate material and a particle size that is mainly capable of forward scattering sunlight incident from the outside to the inside of the light-diffusing layer are mainly dispersed. (2) In a photovoltaic panel unit according to another embodiment, preferably, at least one light-transmitting layer may be placed between the module and the light-diffusing layer. (3) In a photovoltaic panel unit according to another embodiment, preferably the particles are silicone resin particles. (4) In a photovoltaic panel unit according to another embodiment, preferably the light diffusion layer mainly contains particles having a diameter larger than the wavelength in the visible light range. (5) In a solar power generation panel unit according to another embodiment, preferably the plate material may be composed of a resin mainly composed of polymethyl methacrylate (PMMA). [Effects of the Invention]

[0009] According to the present invention, it is possible to obtain the necessary power for a long period of time, even on sunny days. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows a schematic configuration of a power generation device equipped with a solar panel unit according to one embodiment. [Figure 2] Figure 2 shows a schematic cross-sectional view of a photovoltaic panel, a main component of the power generation device shown in Figure 1, when it is cut in the thickness direction, and an enlarged view of the light diffusion plate layer and a part P of the light diffusion layer that make up the panel. [Figure 3] Figure 3 shows cross-sectional views of a conventional solar power generation panel unit (3A) without a light diffusion layer and the solar panel unit (3B) shown in Figure 2. [Figure 4] Figure 4 shows the light scattering situation in the light diffusion layer of the panel unit in Figure 2, where (4A) mainly shows the Mie scattering, and (4B) mainly shows the light diffusing within the light diffusion layer while Mie scattering before entering the module. [Modes for carrying out the invention]

[0011] Next, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below are not intended to limit the invention as defined in the claims, and not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the present invention.

[0012] Figure 1 shows a schematic configuration of a power generation device equipped with a photovoltaic panel unit according to one embodiment. Figure 2 shows a schematic cross-sectional view of the photovoltaic panel, which is the main component of the power generation device in Figure 1, when cut in the thickness direction, and an enlarged view of the light diffusion plate layer and a part P of the light diffusion layer that constitute the panel.

[0013] A power generation device A equipped with a solar panel unit (hereinafter referred to as "panel unit") 1 according to this embodiment comprises the panel unit 1 as the main component of the device A, a pole 2 supporting it, and a base 3 for fixing the pole 2 to the ground G. The power generation device A is not limited to the above configuration and may be any form of device as long as it includes the panel unit 1. For example, when the power generation device A is installed on a roof, the power generation device A is configured to fix the panel unit 1 to the roof and does not include the pole 2 and base 3. The panel unit 1 is fixed to the pole 2 so that the surface that receives light L from the sun S (light-receiving surface) is inclined with respect to the ground G. However, the light-receiving surface of the panel unit 1 may be arranged parallel to the ground G.

[0014] As shown in Figure 2, the panel unit 1 comprises at least a module 10 having multiple cells for photovoltaic power generation, and a light-diffusing layer 13 disposed on one side in the thickness direction of the module 10. Preferably, the panel unit 1 has at least one light-transmitting layer 12 between the module 10 and the light-diffusing layer 13. However, the light-transmitting layer 12 may be the outermost layer of the panel unit 1, and the light-diffusing layer 13 and module 10 may be arranged in that order toward the layers below it. The light-diffusing layer 13 may be an additional layer added to the laminate of the other layers, or it may be laminated integrally with the laminate to form the panel unit 1.

[0015] The panel unit 1 further preferably has a backsheet 11 disposed on the surface opposite to the light diffusion layer 13 of the module 10. The plurality of layers constituting the panel unit 1 are preferably fixed by a frame 14 in the thickness direction of the panel unit 1. The frame 14 is provided on the outer periphery of the panel unit 1.

[0016] The module 10 is a panel assembly in which cells as the minimum units of solar power generation are assembled in a panel shape. Each cell in the module 10 is electrically connected by electrodes. A plurality of modules 10 may be further grouped together as an array.

[0017] The light-transmitting layer 12 is a layer that can transmit the light incident on the panel unit 1 and supply it to the module 10, and is also a layer that protects the module 10 from impact. The light-transmitting layer 12 is generally made of glass (including tempered glass) or resin (for example, polymethyl methacrylate: PMMA), but the constituent material thereof is not limited to these.

[0018] The backsheet 11 functions as a layer that protects the module 10 from impact and also as a reflection layer that returns part of the light from the sun S that did not enter the module 10 to the module 10 side.

[0019] The light diffusion layer 13 is a layer in which particles 33 having a refractive index different from that of the light-transmissive resin or glass plate material 23 and having a particle size capable of mainly forward-scattering sunlight incident from the outside to the inside of the light diffusion layer 13 are mainly dispersed (forward scattering will be described later). The light diffusion layer 13 is preferably a layer mainly dispersing particles 33 having a diameter larger than the wavelength in the visible light region. The refractive index of the particles 33 may be smaller than the refractive index of the plate material 23, but is preferably larger than the refractive index of the plate material 23. For example, when the plate material 23 is mainly composed of a PMMA (refractive index: 1.49) resin, it is preferable to configure the particles 33 with a material having a refractive index larger than the above refractive index (1.49). Here, "mainly" means that the material exceeding 50% by volume of the plate material 23 (excluding the particles 33) is PMMA.

[0020] The plate material 23 preferably contains PMMA at a ratio exceeding at least 50% by volume, more preferably at a ratio exceeding 70% by volume, and still more preferably at a ratio exceeding 90% by volume.

[0021] The particles 33 are preferably composed of resin, metal or ceramics. When the particles 33 are composed of resin, examples of the resin include silicone resin. Examples of the particles 33 include particles composed of one or more of silica (refractive index: 1.43 to 1.67), alumina (refractive index: 1.63 to 1.70), and titanium oxide (refractive index: 2.52 to 2.71) in addition to the silicone resin particles. The particles 33 mainly have a diameter larger than the wavelength in the visible light region (360 nm to 830 nm). Here, "mainly" means more than 50% of the number of the particles 33 dispersed in the plate material 23. Therefore, more than half of all the particles 33 dispersed in the plate material 23 have a diameter larger than the wavelength in the visible light region. For example, when the average particle diameter based on the number of the particles 33 is 0.9 μm (900 nm), the particles 33 mainly have a diameter larger than the wavelength in the visible light region (360 nm to 830 nm).

[0022] Preferably, at least 50% of the particles 33 have a diameter larger than the wavelength of visible light, and more preferably, over 70%, and even more preferably over 90%, have a diameter larger than the wavelength of visible light. The method for measuring the average particle diameter of particles 33 is laser diffraction / scattering (also simply called "laser diffraction").

[0023] Thus, the reason for imposing the above constraints on the refractive index of the particles 33, and more preferably on the particle size, is to facilitate Mie scattering of the light L that enters the light diffusion layer 13, as will be described later.

[0024] Figure 3 shows cross-sectional views of a conventional solar power generation panel unit (3A) without a light diffusion layer and the solar panel unit (3B) shown in Figure 2.

[0025] If the light diffusion layer 13 is not provided, as shown in (3A), some of the light from the sun S will pass through the light-transmitting layer 12 but will not enter the module 10, or some of the light will be reflected by the light-transmitting layer 12. On the other hand, if the light diffusion layer 13 is provided, as shown in (3B), the light from the sun S will not be easily reflected by the light diffusion layer 13 and will tend to enter the module 10 after being incident on the light diffusion layer 13 and refracted multiple times.

[0026] Figure 4 shows the light scattering situation in the light diffusion layer of the panel unit in Figure 2, where (4A) mainly shows the Mie scattering, and (4B) mainly shows the light diffusing within the light diffusion layer while Mie scattering before entering the module.

[0027] Light scattering can be broadly classified into Rayleigh scattering and Mie scattering. Rayleigh scattering refers to scattering by particles that are significantly smaller than the wavelength of light (mainly visible light). On the other hand, Mie scattering refers to scattering by particles that are roughly the same size as or larger than the wavelength of light. In the case of Mie scattering, the light does not depend on the wavelength when it strikes a particle, so it appears white. One characteristic of Mie scattering is that when the particle is large relative to the wavelength of light, forward scattering becomes more dominant than backscattering.

[0028] The light diffusion layer 13 contains dispersed particles 33 having a diameter larger than the wavelength of visible light. Therefore, as shown in (4A), when light L strikes the particles 33, forward scattering (F), which is scattering in the direction of light propagation, is more likely to occur than backscattering (B), which is scattering on the opposite side of the direction of light propagation. The particles 33 have a particle size that is mainly capable of forward scattering sunlight (light L) incident from the outside to the inside of the light diffusion layer 13. The diameter of the particles 33 that are most likely to cause forward scattering is preferably 1 μm or more, more preferably 1 μm to 100 μm, and even more preferably 2 μm to 50 μm.

[0029] Light L from the sun S enters the light diffusion layer 13 and diffuses within the light diffusion layer 13, predominantly undergoing forward scattering upon contact with many particles 33. Light in contact with the outer surface of the light diffusion layer 13 is less likely to be reflected by the outer surface, and even when incident on the outer surface at an oblique angle, it is predominantly diffused by forward scattering, so it tends to be incident on the module 10 almost uniformly from the back surface of the light diffusion layer 13 (i.e., the surface closer to the module 10). As a result, sufficient incident light on the module 10 can be secured even in the morning or evening on a clear day. Preferably, the light diffusion layer 13 is treated to prevent surface reflection. Examples of such treatments include AR coating and dipping. Other examples include nanoimprinting (transfer) of uneven surface processing, surface etching, or mixing particles (whether or not they are the same particles as particles 33) as a diffusing material (diffuser material) to reduce surface reflection. With such surface treatment, the light diffusion layer 13 becomes a layer that combines light diffusion, forward scattering, and reduction of surface reflection.

[0030] Although one embodiment of the present invention has been described above, it can be implemented in various modified forms without departing from the spirit of the present invention.

[0031] Each layer constituting the panel unit 1, namely the module 10, the light-transmitting layer 12, the backsheet 11, and the light-diffusing layer 13, may be a single layer, or any of them may be two or more layers. Furthermore, the light-transmitting layer 12 and the backsheet 11 are not essential layers for the panel unit 1, and at least one of them may be omitted.

[0032] The light diffusion layer 13 is preferably a layer that predominantly generates forward scattering, but it may also be a layer in which forward scattering and back scattering are of equal magnitude. [Industrial applicability]

[0033] This invention can be used for solar power generation. [Explanation of Symbols]

[0034] 1...Solar power generation panel unit (panel unit), 10...Module, 12...Translucent layer, 13...Light diffusing layer, 23...Sheet material, 33...Particles.

Claims

1. A module equipped with multiple cells for solar power generation, A light-diffusing layer is disposed on one side in the thickness direction of the module, It has at least the following features: A solar power generation panel unit characterized in that the light diffusion layer is a layer in which particles having a different refractive index from that of the translucent resin or glass plate material and having a particle size that is mainly capable of forward scattering sunlight incident from the outside to the inside of the light diffusion layer are mainly dispersed.

2. The photovoltaic panel unit according to claim 1, characterized in that at least one light-transmitting layer is disposed between the module and the light-diffusing layer.

3. The solar power generation panel unit according to claim 1, characterized in that the particles are silicone resin particles.

4. The photovoltaic panel unit according to claim 1, characterized in that the light diffusing layer mainly disperses particles having a diameter larger than the wavelength in the visible light range.

5. The photovoltaic panel unit according to claim 1, characterized in that the plate material is composed mainly of a resin made of polymethyl methacrylate (PMMA).

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