JP7540466B2 - Window structure with transparent solar cells installed - Google Patents

Description

The present invention relates to a window structure for vehicles or buildings in which transparent glass or resin is embedded, and more specifically, to a window structure equipped with a transparent solar cell that transmits visible light and allows light into the room while generating electricity.

Attempts have been made to mount solar cells on the roofs of vehicles such as automobiles and buildings, and to use the generated electric energy for various operations in the vehicle and various devices in the building (for example, Patent Document 1, etc.). In this regard, in the case of general solar cells (Patent Document 2, etc.), since they do not transmit light, such solar cells cannot be placed on windows for lighting in vehicles or buildings. However, in recent years, transparent solar cells (Patent Document 3, etc.) that transmit light with wavelengths in the visible light range and generate electricity using light in the ultraviolet range or near infrared range have been developed, and such transparent solar cells can be used as windows that can generate electricity while lighting by being fitted into a window frame for lighting or by being installed on a window. In addition, Patent Document 4 proposes that a back surface protective sheet be laminated on the non-light receiving side of a solar cell to improve the design of a solar cell module that absorbs light in the near infrared region and to prevent a decrease in power generation efficiency. The back surface protective sheet is made by laminating a transparent adhesive resin layer containing a wavelength conversion agent that converts light on the long wavelength side of the visible light region to light with a longer wavelength on top of a reflective layer that reflects light in the near infrared region. The transparent adhesive resin layer converts the long wavelength side light in the visible light region that reaches the back surface of the solar cell to light in the near infrared region, and the reflective layer reflects the light in the near infrared region to increase the efficiency of using light in the visible light region.

Patent Publication 2009-10127 Patent Publication No. 2021-168322 Patent Publication No. 2018-32872 Patent Publication No. 2018-82031

In a configuration in which a transparent solar cell that transmits visible light (hereinafter referred to as a "transparent solar cell") is placed in a window of a vehicle or building (i.e., an area within a light-transmitting window frame opened in a wall structure that separates the interior and exterior of a vehicle or building) as described above, the transparent solar cell transmits visible light, so the energy of visible light is not used to generate electricity, and the efficiency of using solar energy is accordingly lower than that of a solar cell that generates electricity using light over a wide range of wavelengths of sunlight.

In some cases, windows in vehicles or buildings are provided with a movable light-blocking shade (an interior panel or curtain for blocking light) on the interior side of the window for shading or privacy. If a layer (wavelength conversion layer) containing a wavelength conversion material such as a fluorescent material that absorbs visible light and emits near-infrared light is laminated on such a movable shade, and visible light that has passed through a transparent solar cell is incident on the wavelength conversion layer, and the emitted near-infrared light is returned to the transparent solar cell, then while the shade is covering the window, the visible light contained in the sunlight is converted to near-infrared light and then absorbed by the transparent solar cell, and can be recovered as electricity, thereby improving the efficiency of solar energy utilization. In this case, it is even more advantageous if as much near-infrared light as possible emitted from the wavelength conversion layer on the shade is returned to the transparent solar cell.

Thus, one objective of the present invention is to enable transparent solar cells to be installed in the windows of vehicles or buildings, in a window structure that allows light to enter while generating electricity, and to recover as much light energy as possible as electrical energy using the transparent solar cells.

A more detailed objective of the present invention is to apply a wavelength conversion layer that absorbs visible light and emits near-infrared light to the exterior side of the shade in the window structure described above, and while the shade is blocking sunlight from the window, the wavelength conversion layer converts the visible light components of the sunlight that has passed through the transparent solar cell into near-infrared light, and returns as much of the converted near-infrared light as possible to the transparent solar cell, so that as much light energy as possible can be recovered as electrical energy by the transparent solar cell.

According to one aspect of the present invention, the above problem is solved by providing a window structure in which a transparent solar cell that transmits visible light and absorbs near-infrared light to generate electricity is installed in an area within a light-transmitting window frame opened in a wall structure separating indoors and outdoors, the transparent solar cell being irradiated with sunlight from the outdoor side of the window structure, and absorbing the near-infrared light component in the sunlight to generate electricity,
A movable shade is provided that can cover at least a part of the area within the window frame on the indoor side of the window structure and can be arranged to block light that transmits through at least a part of the area within the window frame from the outdoor side to the indoor side of the window structure;
A reflective layer that reflects at least near-infrared light is applied to the outdoor surface of the shade;
A wavelength conversion layer that converts visible light into near-infrared light and emits the near-infrared light is laminated on the reflective layer,
This is achieved by a window structure configured such that, when the shade is positioned in a position covering at least a portion of the area within the window frame, the near-infrared light emitted by the wavelength conversion layer after absorbing visible light that has passed through the transparent solar cell is reflected by the reflective layer and irradiated onto the transparent solar cell.

In the above configuration of the present invention, the "wall structure separating indoors and outdoors" may be the outer wall of a vehicle body such as an automobile, the outer wall of a building, etc. In the case of a vehicle, the "window structure" may be a window structure in which a transparent flat glass material or resin material is embedded in an area within a window frame formed on the outer wall of the vehicle body, such as a front window, a side window, a rear window, or a skylight (sunroof, panoramic roof). In the case of a building, the "window structure" may be a window structure in which a transparent flat glass material or resin material is embedded in an area within a window frame formed on the outer wall of the building. As described in Patent Document 3, the "transparent solar cell" may be any type of solar cell that transmits visible light and absorbs near-infrared light to generate electricity, and may be installed by being embedded in an area within a window frame as part of a transparent flat glass material or resin material, or by being attached to a transparent flat glass material or resin material. Thus, as described above, when sunlight is irradiated from outside onto a transparent solar cell installed in the area within the window frame, the visible light components in the sunlight are transmitted through the transparent solar cell, while the near-infrared light components are absorbed by the transparent solar cell and converted into electricity.

In the window structure of the present invention, a movable shade is installed on the indoor side so as to cover at least a part of the area within the window frame and to block light passing through at least a part of the area within the window frame from the outdoor side to the indoor side of the window structure. That is, the shade is configured to be moved to a position that does not cover the area within the window frame when it is desired to let light into the room from the window structure, and to be moved to a position that covers the area within the window frame when it is desired to block light from the window structure into the room. In such a shade, a reflective layer that reflects at least near-infrared light is first applied to the outdoor side surface, and a wavelength conversion layer that absorbs visible light and emits near-infrared light is laminated on the reflective layer. The wavelength conversion layer may be a layer that absorbs visible light in any form and emits near-infrared light, and typically may be a fluorescent layer in which a fluorescent material that absorbs visible light and emits near-infrared light is dispersed, but is not limited thereto (a phosphorescent material that absorbs visible light and emits near-infrared light may be used). According to this configuration, when the shade is in a position that covers at least a portion of the area within the window frame, the wavelength conversion layer faces the transparent solar cell, so that the visible light components that pass through the transparent solar cell are incident on the wavelength conversion layer, which causes near-infrared light to be emitted from the wavelength conversion layer, some of which directly enters the transparent solar cell, and the other part is reflected by the reflective layer and enters the transparent solar cell. In this state, the transparent solar cell can generate electricity not only using near-infrared light from sunlight, but also using the visible light components from sunlight, so that more solar energy can be recovered as electrical energy.

In the above-described configuration of the present invention, the near-infrared light converted from visible light by the wavelength conversion layer can also be emitted from the edge surface of the wavelength conversion layer. Therefore, in order to make it possible to effectively use the near-infrared light emitted from the edge surface of the wavelength conversion layer for power generation, the reflective layer of the shade may be formed to cover the edge of the wavelength conversion layer, and may be configured so that the near-infrared light emitted from the edge of the wavelength conversion layer is irradiated onto the transparent solar cell. Specifically, the reflective layer may be formed to be thicker toward the edge portion than in the central region, and may have a shape that is inclined so that the reflective surface of the edge portion faces the transparent solar cell.

Thus, according to the present invention, in a configuration in which transparent solar cells are installed in the window structure of a vehicle or building and can collect light while generating electricity, when light collection from the window is not necessary and the window is covered with a shade, the visible light transmitted through the transparent solar cell is converted to near-infrared light in the shade and returned to the transparent solar cell, so that the energy of visible light in sunlight can also be converted into electricity and recovered, thereby improving the efficiency of solar energy utilization. Furthermore, when the reflective layer is formed to cover the edge of the wavelength conversion layer, more of the visible light energy is returned to the transparent solar cell, further improving the efficiency of solar energy utilization.

Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention.

1A and 1B are schematic diagrams of a vehicle and a building having a window structure to which this embodiment is applied. FIG. 2(A) is a schematic cross-sectional view of a window structure to which this embodiment is applied when the shade is not covering the window, and FIG. 2(B) is a schematic cross-sectional view of a window structure to which this embodiment is applied when the shade is covering the window.

REFERENCE SIGNS LIST 1 vehicle 1a exterior wall of vehicle 1w window frame 2, 4 window 2a, 4a transparent solar cell 3 building 3a exterior wall of building 10 shade 12 reflective layer 12e edge of reflective layer 14 wavelength conversion layer (fluorescent layer)
irl...near infrared light vl...visible light S...sunlight

As shown in FIGS. 1(A) and 1(B), the configuration of this embodiment may be applied to the structure of a window 2 such as a front window, a side window, a rear window, or a skylight formed on an outer wall that defines the passenger compartment of a vehicle 1, or to the structure of a window 4 formed on the outer wall of a building 3.

Referring to Figures 2(A) and (B), in the windows 2 and 4 of this embodiment, specifically, first, a flat plate made of a transparent glass material or resin material is fitted into the window frame 1w, 3w that is opened in the exterior wall 1a, 3a that separates the outside side O from the inside side I to allow light in from the outside side O, and then a transparent solar cell 2a that transmits visible light and absorbs near-infrared light to generate electricity is installed in or on the flat plate. Note that a transparent solar cell 2a is a solar cell that, when one side of the solar cell is observed with the naked eye, the other side is visible through it, and any type of solar cell having such characteristics may be used.

2(B), when blocking light from the outside O on the indoor side I of the windows 2, 4, a movable shade 10 is provided so as to be positioned to cover the windows 2, 4. The shade 10 may be moved as appropriate along the surfaces of the windows 2, 4 in the direction of the arrow X as shown, for example, and may be movably slid between a "fully open position" that does not cover the entire windows 2, 4 but allows light in and a "fully closed position" that covers the entire windows 2, 4 and blocks light, and may be positioned at any position. Alternatively, although not shown, the shade 10 may be hingedly pivoted relative to the window structure 2, 4 between a "fully open position" that does not cover the entire windows 2, 4 and a "fully closed position" that covers the entire windows 2, 4.

In the above shade 10, as shown in the figure, a reflective layer 12 is laminated on the outdoor side of the interior panel or interior curtain 11, and a wavelength conversion layer 14 that converts visible light vl to near-infrared light irl is laminated on the reflective layer 12. The reflective layer 12 may be any type of layer, for example, a mirror layer, that reflects light propagating from the outdoor side O to the indoor side I toward the outdoor side O, i.e., the transparent solar cell 2a. The wavelength conversion layer 14 may be a layer that converts visible light vl to near-infrared light irl (light with a wavelength that can be converted into electricity by the transparent solar cell 2a) in any manner, and may typically be a layer formed of a translucent material in which a fluorescent or phosphorescent substance that absorbs visible light vl and emits near-infrared light irl is dispersed. As the fluorescent or phosphorescent substance, any pigment substance or quantum dot that absorbs visible light vl and emits near-infrared light irl may be used.

In the above-mentioned wavelength conversion layer 14, the near-infrared light irl converted from the visible light vl is usually emitted in all directions from the wavelength conversion layer 14. However, the reflective layer 12 may be formed so that the edge surface of the wavelength conversion layer 14 is also covered by a part of the reflective layer 12 so that the near-infrared light irl emitted from the edge surface of the wavelength conversion layer 14 is directed toward the transparent solar cell 2a. More preferably, as shown in the figure, the edge portion 12e of the reflective layer 12 may be inclined so that the reflective surface faces the transparent solar cell 2a so that the light emitted from the edge surface of the wavelength conversion layer 14 is directed toward the transparent solar cell 2a.

As shown in Fig. 2(A) of the operation of the window structure of this embodiment , when the transparent solar cell 2a is installed in the window frames 1w, 3w, when sunlight S is incident from the outdoor side O of the exterior walls 1a, 3a to the indoor side I, the transparent solar cell 2a absorbs the near-infrared light (700 nm or more) irl in the sunlight and converts it into electricity (generates electricity), while transmitting the visible light (380 nm to 700 nm) vl in the sunlight, so that it is possible to take in light visible to the naked eye to the indoor side I while generating electricity with the transparent solar cell. However, because the visible light vl is incident on the indoor side I, the energy of the visible light vl cannot be recovered as electricity.

When lighting through the windows 2, 4 is not necessary or desired in the vehicle 1 or building 3, a light-opaque shade 10 is placed along the windows 2, 4 so as to cover at least a portion of the windows 2, 4, as shown in FIG. 2(B) above. In this embodiment, therefore, a wavelength conversion layer 14 that converts visible light vl to near-infrared light irl, and a reflective layer 12 that directs the near-infrared light emitted therefrom toward the transparent solar cell 2a are provided on the side of the shade 10 facing the windows 2, 4, as described above.

According to this configuration, as shown in FIG. 2(B), when the shade 10 is arranged along the windows 2 and 4, first, when sunlight is irradiated onto the windows 2 and 4, the near-infrared light irl in the sunlight is absorbed by the transparent solar cell 2a and converted into electricity as described above. On the other hand, the visible light vl transmitted through the transparent solar cell 2a reaches the wavelength conversion layer 14, where it is converted into near-infrared light irl and emitted. Of the near-infrared light irl, the component propagating toward the transparent solar cell 2a reaches the transparent solar cell 2a as is, the component propagating away from the transparent solar cell 2a is reflected by the reflective layer 12 and reaches the transparent solar cell 2a, and further, the component emitted from the edge surface of the wavelength conversion layer 14 is reflected by the inclined edge portion 12e of the reflective layer 12 and reaches the transparent solar cell 2a. Thus, all of the near-infrared light components emitted in various directions from the wavelength conversion layer 14 reach the transparent solar cell 2a, where they are absorbed and converted into electricity. As a result, while the shade 10 is covering the windows 2 and 4, not only the near-infrared light energy in the sunlight but also the visible light energy can be converted into electricity and collected by the transparent solar cell 2a, making it possible to improve the efficiency of using sunlight.

The above description is given in relation to an embodiment of the present invention, but many modifications and changes are easily possible for those skilled in the art, and it is clear that the present invention is not limited to the embodiment exemplified above, but can be applied to various devices without departing from the concept of the present invention.

Claims (5)

A window structure in which a transparent solar cell that transmits visible light and absorbs near-infrared light to generate electricity is installed in an area within a light-transmitting window frame opened in a wall structure separating indoors and outdoors, the transparent solar cell being irradiated with sunlight from the outdoor side of the window structure and absorbing the near-infrared light component in the sunlight to generate electricity,
A movable shade is provided that can cover at least a part of the area within the window frame on the indoor side of the window structure and can be arranged to block light that transmits through at least a part of the area within the window frame from the outdoor side to the indoor side of the window structure;
A reflective layer that reflects at least near-infrared light is applied to the outdoor surface of the shade;
A wavelength conversion layer that converts visible light into near-infrared light and emits the near-infrared light is laminated on the reflective layer,
A window structure configured such that, when the shade is positioned to cover at least a portion of the area within the window frame, the wavelength conversion layer absorbs visible light that has passed through the transparent solar cell and emits near-infrared light, which is reflected by the reflective layer and irradiated onto the transparent solar cell. The window structure of claim 1, wherein the reflective layer is formed to cover the edge of the wavelength conversion layer, and the window structure is configured so that near-infrared light emitted from the edge of the wavelength conversion layer is irradiated onto the transparent solar cell. The window structure of claim 1, wherein the wavelength conversion layer is a fluorescent layer in which a fluorescent material that absorbs visible light and emits near-infrared light is dispersed. A window structure according to any one of claims 1 to 3, which is formed in a vehicle. A window structure according to any one of claims 1 to 3, which is formed in a building.

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