Glass Building Materials

Abstract

To achieve an increase in a power generation amount at a light-receiving surface on an interior side.SOLUTION: The glass building includes: a solar battery array including a first double-side light-receiving solar battery with a shape extending in a first direction; a second double-side light-receiving solar battery which is arranged in line with the first solar battery in a second direction crossing in the first direction and has a shape extending in the first direction; a first glass substrate covering a first main surface side of the solar battery array; a reflection coating which is at least partially arranged on a second main surface side of the solar battery array and which has a higher transmission factor than a reflection factor in a visible light area and a higher reflection factor than a transmission factor in a near infrared area; and an air space interposed between the solar battery array and the reflection coating in a specific direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a glass building material. [Background technology]

[0002] Non-Patent Document 1 listed below discloses a bifacial solar cell that is installed vertically to the ground. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Development of Basic Application Technology for Bifacial Solar Cells" by Toshio Kamiue et al., Journal of Electrical Engineering B, Vol. 123, No. 8, 2003, pp. 947-955 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when conventional bifacial solar cells are installed on windows of buildings, the amount of electricity generated by the indoor light-receiving surface is small. In other words, the indoor light-receiving surface cannot efficiently receive sunlight from the outside, and as a result, the amount of electricity generated is low.

[0005] On the other hand, conventional daylight harvesting type solar cell modules use glass with high solar transmittance in order to increase the amount of power generated, which results in an increase in the cooling load of buildings.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to increase the amount of electricity generated on the light-receiving surface on the indoor side when a glass building material including a solar cell is installed in a window of a building, etc.

[0007] Furthermore, the aim is to reduce the cooling load and save energy in the building, while also ensuring a view without a feeling of oppression and improving lighting performance. [Means for solving the problem]

[0008] (1) A glass building material according to the present disclosure includes a solar cell array including a first solar cell of a bifacial type having a shape extending in a first direction and a second solar cell of a bifacial type arranged alongside the first solar cell in a second direction intersecting the first direction and having a shape extending in the first direction; a first glass substrate covering a first main surface side of the solar cell array; a reflective film arranged at least partially on the second main surface side of the solar cell array, the reflective film having a transmittance higher than a reflectance in the visible light region and a reflectance higher than the transmittance in the near-infrared region; and an air layer interposed between the solar cell array and the reflective film.

[0009] (2) In the above glass building material, the distance between the reflective film and the first solar cell may be 0.5 or more times the length of the first solar cell in a direction perpendicular to the first direction.

[0010] (3) The above glass building material may further include a first reflector facing the second main surface of the first solar cell and extending in the first direction.

[0011] (4) In the above glass building material, a length of the first reflector in a direction perpendicular to the first direction may be equal to or greater than a length of the first solar cell in the direction perpendicular to the first direction.

[0012] (5) In the above glass building material, the first reflector may be arranged on a surface of the reflective film that does not face the first solar cell.

[0013] (6) The above glass building material may further include a second glass substrate disposed between the first reflector and the reflective film.

[0014] (7) The above glass building material may further include a fourth glass substrate disposed between the first reflector and the second glass substrate.

[0015] (8) The above glass building material may further include a fifth glass substrate disposed between the air layer and the reflective film.

[0016] (9) The above glass building material may further include a sixth glass substrate disposed between the fifth glass substrate and the reflective film.

[0017] (10) The above glass building material may further include a third glass substrate interposed between the solar cell array and the air space.

[0018] (11) The above glass building material may further include a sealant interposed between the first solar cell and the second solar cell.

[0019] (12) In the above glass building material, the first solar cell may have a spectral sensitivity in a wavelength range of at least 300 nm to 1200 nm.

[0020] (13) In the above glass building material, the first solar cell may be a heterojunction solar cell.

[0021] (14) In the above glass building material, the reflective film may be configured to reflect at least near-infrared light in sunlight incident from the first main surface side of the first solar cell and allow the light to be incident on the second main surface of the first solar cell.

[0022] (15) In the above glass building material, the reflective film may have an uneven surface, so that the near-infrared light is diffusely reflected and made to be incident on the second main surface of the first solar cell.

[0023] (16) In the above glass building material, the first reflector may be configured to reflect at least near-infrared components and visible light components of sunlight incident from the first main surface side of the first solar cell, and cause the reflected light to be incident on the second main surface of the first solar cell. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a plan view showing an outline of a glass building material according to this embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing an outline of the glass building material according to this embodiment. [Diagram 3] FIG. 3 is a graph showing the wavelength dependence of the spectral sensitivity of the first solar cell and the reflectance of the reflective film in the glass building material according to this embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between the distance between the first solar cell and the reflective film according to this embodiment and the rate of increase in output. [Diagram 5] FIG. 5 is a cross-sectional view showing another example of the glass building material according to the present embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing another example of the glass building material according to this embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing another example of a glass building material according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described below with reference to the drawings.

[0026] Fig. 1 is a plan view showing an outline of a glass building material according to the present embodiment, and Fig. 2 is a cross-sectional view showing a cross section taken along line II-II in Fig. 1.

[0027] As shown in Fig. 1, the glass building material 100 has a solar cell array consisting of a plurality of solar cells 13 arranged at intervals, and a first glass substrate 21 provided so as to cover a first main surface side of the solar cell array. The plurality of solar cells 13 may be single crystal silicon solar cells, polycrystalline silicon solar cells, heterojunction solar cells, or the like, and the type is not particularly limited. In this embodiment, the plurality of solar cells 13 will be described using heterojunction solar cells.

[0028] Here, the first glass substrate 21 is, for example, a glass substrate that is attached as a window of a building, and is made of a material with high transmittance so as to allow sunlight to enter the interior of the room and onto the surface of the solar cell.

[0029] As shown in FIG. 1 and FIG. 2, the solar cell array includes a first solar cell 11 and a second solar cell 12. The first solar cell 11 and the second solar cell 12 are configured by arranging and connecting a plurality of solar cells in a straight line, and have a shape extending in a first direction, and the first solar cell 11 has a width W1. The width W1 means the length of the first solar cell 11 in a direction perpendicular to the first direction. The second solar cell 12 is arranged next to the first solar cell 11 in a second direction intersecting the first direction, and the first solar cell 11 and the second solar cell 12 are arranged with a first interval W2 between them. The width direction of the first solar cell 11 and the second solar cell 12 and the extension direction of the first solar cell 11 and the second solar cell 12 are perpendicular to each other. In addition, the first direction in which the first solar cell 11 and the second solar cell 12 extend and the second direction in which the multiple solar cells 13 are arranged do not necessarily need to be perpendicular to each other, as long as they intersect.

[0030] The relative spectral sensitivity of first solar cell 11 is sensitive to approximately 300 nm to 1200 nm, with a high value around 1000 nm in the near-infrared region, as shown in Fig. 3. First solar cell 11 and second solar cell 12 are bifacial types, and light received from first main surfaces 11A, 12A facing the outdoor side and second main surfaces 11B, 12B facing the indoor side can be contributed to power generation.

[0031] As shown in FIG. 2, first main surface 11A of first solar cell 11 and first main surface 12A of second solar cell 12 receive sunlight 40 from outside through first glass substrate 21.

[0032] A reflective film 31 is provided on the second main surface 11B side of the first solar cell 11 and on the second main surface 12B side of the second solar cell 12, and is arranged at a second distance d from the first solar cell 11 and the second solar cell 12. In this embodiment, the reflective film 31 is provided on the surface of the second glass substrate 22. This reflective film 31 is, for example, a Low-E (Low Emissivity) film, and in this embodiment, a heat-shielding Low-E film that transmits most of the visible light and reflects most of the near-infrared light will be used for explanation.

[0033] FIG. 3 is a diagram showing the wavelength dependence of the spectral sensitivity of the first solar cell 11 and the second solar cell 12 and the reflectance of the reflective film 31 (reflective film 31A, reflective film 31B, reflective film 31C) in the glass building material according to this embodiment. In this embodiment, the first solar cell 11 and the second solar cell 12 are the same type of heterojunction solar cell, so they have the same spectral sensitivity characteristics, and are shown as "hetero spectral sensitivity" in FIG. 3. As shown in FIG. 3, each of the reflective films 31A, 31B, and 31C has a high reflectance in the near-infrared region of 750 to 2500 nm, and in this near-infrared region, the reflectance is higher than the transmittance. On the other hand, each of the reflective films 31A, 31B, and 31C has a low reflectance in the visible light region of 380 to 750 nm, and in this visible light region, the transmittance is higher than the reflectance.

[0034] Since such a reflective film 31 is provided on the second main surface 11B side of the first solar cell 11, a portion of the near-infrared component 41 in the sunlight incident from outside is reflected by this reflective film 31 and received by the second main surface 11B of the first solar cell 11 and the second main surface 12B of the second solar cell 12. As described above with reference to Fig. 3, the first solar cell 11 and the second solar cell 12 have high spectral sensitivity characteristics in the near-infrared region, and the near-infrared component 41 reflected by the reflective film 31 can be efficiently contributed to power generation.

[0035] On the other hand, part of the visible light component 42 of the sunlight entering from outside passes through the reflective film 31, which has a low reflectance in the visible light region, and enters the room. Therefore, a view and natural lighting can be secured through this glass building material 100.

[0036] In addition, the near-infrared components of solar radiation are reduced by the reflective film 31, which reduces the cooling load and makes it possible to save energy in the building.

[0037] With this configuration, it is possible to increase the amount of power generated on the light-receiving surface on the indoor side and reduce the cooling load of the building, without losing the function of the glass building material 100 that can ensure views and natural lighting.

[0038] The second interval d between the first solar cell 11 and the reflective film 31 is preferably 0.1 times or more the width W1 of the first solar cell 11, and more preferably 0.5 times or more the width W1. FIG. 4 shows the relationship between the second interval d and the output increase rate of the first solar cell 11 at each aperture ratio. Here, the aperture ratio is the value obtained by dividing the first interval W2 between the first solar cell 11 and the second solar cell 12 by the sum of the width W1 of the first solar cell 11 and the first interval W2. The horizontal axis shows the value obtained by dividing the second interval d by the width W1 of the first solar cell. The vertical axis shows the percentage of the total power generation that is the output increase due to power generation on the indoor light receiving surface, assuming that the power generation on only the outdoor light receiving surface is 100%.

[0039] 4, it can be seen that the rate of increase in output drops sharply when the horizontal axis becomes smaller than 0.1. This indicates that when the second distance d becomes very small, it becomes difficult for the second main surface 11B of the first solar cell 11 to effectively receive the reflected light from the reflective film 31. Therefore, it is desirable that the second distance d between the first solar cell 11 and the reflective film 31 be 0.1 times or more the width W1 of the first solar cell 11.

[0040] Furthermore, as shown in FIG. 4, when the value of the horizontal axis is 0.5 or more, a high output increase rate can be obtained. This is because, for example, as shown in FIG. 2, even when the near-infrared component 41 is incident between the multiple solar cells 13 at an angle close to perpendicular, by increasing the second interval d, it is possible to make the near-infrared component 41 incident on the second main surface side of the multiple solar cells 13. More specifically, the difference between the incident position of the near-infrared component 41 and the incident position of the reflected light in the layer in which the multiple solar cells 13 are arranged becomes larger as the second interval d becomes larger. Therefore, for example, even when the near-infrared component 41 is incident at an angle close to perpendicular at a position away from the first solar cell 11, by increasing the second interval d, it is possible to improve the possibility of the near-infrared component 41 being incident on the first solar cell 11.

[0041] 2, in this embodiment, an air layer 71 is interposed between the solar cell array and the reflective film 31. By interposing the air layer 71, it is possible to increase the second distance d, and a configuration is realized in which the second distance d is 0.5 times or more the width W1 of the first solar cell 11.

[0042] In addition, by providing irregularities on the surface of the reflective film 31 shown in Figure 2, the near-infrared component 41 may be diffusely reflected, and the near-infrared component 41 may be received by the second main surface 11B of the first solar cell 11 and the second main surface 12B of the second solar cell 12 regardless of the incident angle of sunlight.

[0043] In this embodiment, as shown in Fig. 2, a third glass substrate 23 is disposed between the solar cell array and an air layer 71, and a first solar cell 11 and a second solar cell 12 included in the solar cell array are disposed between the first glass substrate 21 and the third glass substrate 23. Furthermore, a sealant 61 is interposed between the first solar cell 11 and the second solar cell 12 between the first glass substrate 21 and the third glass substrate 23, thereby fixing the positions of the first solar cell 11 and the second solar cell 12. The sealant 61 is a thermosetting resin such as EVA (Ethylene Vinyl Acetate Copolymer) resin, and protects the multiple solar cells 13 and fixes the positions of the multiple solar cells 13 in the glass building material 100.

[0044] In this embodiment, as shown in Figure 2, a first reflector 51 facing the second main surface 11B of the first solar cell 11 and a second reflector 52 facing the second main surface 12B of the second solar cell 12 are provided on the side of the reflective film 31 that does not face the first solar cell 11, i.e., on the indoor side of the reflective film 31.

[0045] The first reflector 51 and the second reflector 52 are, for example, a metal plate or a white reflector, and can receive the near-infrared component 41 and the visible light component 42 incident from outside the room onto the second main surface 11B of the first solar cell 11 and the second main surface 12B of the second solar cell 12.

[0046] In this embodiment, the first reflector 51 and the second reflector 52 are attached to the indoor side of the second glass substrate 22, and the second glass substrate 22 is arranged between the first reflector 51, the second reflector 52 and the reflective film 31.

[0047] The first reflector 51 and the second reflector 52 have a shape extending in the first direction, similar to the first solar cell 11 and the second solar cell 12. Therefore, a part of the visible light component 42 in the sunlight incident between the first solar cell 11 and the second solar cell 12 passes between the first reflector 51 and the second reflector 52 and is incident on the above-mentioned reflective film 31. Therefore, a person in the room can see the view outside through the glass building material 100.

[0048] By configuring the width W3 of the first reflector 51 to be larger than the width W1 of the first solar cell, the near-infrared component 41 and the visible light component 42 incident on the first reflector 51 can be more efficiently received by the second main surface 11B of the first solar cell 11, and the light blocking property of the glass building material 100 can be improved. Furthermore, the second main surface 11B side of the first solar cell 11 can be hidden by the first reflector 51, which is a design advantage seen from the indoor side. The width W3 of the first reflector 51 means the length of the first reflector 51 in a direction perpendicular to the first direction.

[0049] Furthermore, by arranging the first reflector 51 and the second reflector 52 on the side of the second glass substrate 22 that does not face the first solar cell 11, i.e., on the indoor side, the relative positional relationship of the first reflector 51 and the second reflector 52 with respect to the first solar cell 11 and the second solar cell 12 can be adjusted with high precision. That is, after the positions of the first glass substrate 21 and the second glass substrate 22 are fixed by the sealing material 61, the first reflector 51 and the second reflector 52 can be arranged while checking the positions of the first solar cell 11 and the second solar cell 12, so that they can be arranged at desired positions with high precision.

[0050] As shown in FIG. 5, a fourth glass substrate 24 may be further provided between the first reflector 51 and the second glass substrate 22, and between the second reflector 52 and the second glass substrate 22.

[0051] 6, a fifth glass substrate 25 may be further provided between the air layer 71 and the reflective film 31. With this configuration, the second distance d can be controlled by controlling the film thickness of the fifth glass substrate 25.

[0052] Furthermore, as shown in FIG. 7, a sixth glass substrate 26 may be further provided between the fifth glass substrate 25 and the reflective film 31. With this configuration, the second distance d can be controlled by controlling the film thicknesses of the fifth glass substrate 25 and the sixth glass substrate 26. In the example shown in FIG. 7, the second glass substrate 22, the first reflector 51, and the second reflector 52 are not provided on the side of the reflective film 31 that does not face the first solar cell 11, i.e., on the indoor side. However, the second glass substrate 22, the first reflector 51, and the second reflector 52 may be provided on the indoor side of the reflective film 31, as in the configuration described above with reference to FIGS. 2, 5, and 6.

[0053] In this embodiment, a Low-E film is used as an example of the reflective film 31, but other films may be used as long as the transmittance in the visible light region is higher than the reflectance and the reflectance in the near-infrared region is higher than the transmittance. For example, the reflective film 31 may be a transparent conductive film TCO that is designed to increase the reflectance in the near-infrared region by adjusting the tin oxide content. The reflective film 31 may also be composed of multiple reflective films with different reflection peaks for different wavelengths. [Explanation of symbols]

[0054] 11 The first solar cell 11A first principal surface 11B Second main surface 12 Second solar cell 12A First Principal Surface 12B Second main surface 13 Multiple solar cells 21 First glass substrate 22 Second glass substrate 23 Third Glass Substrate 24 Fourth Glass Substrate 25 Fifth Glass Substrate 26 6th Glass Substrate 31 Reflective film 40. Sunlight 41 Near-infrared component 42 Visible light component 51 First Reflector 52 Second reflector 61 Encapsulating materials 71 Air Layer 100 Glass building materials W1 width W2 First interval W3 width d Second interval

Claims

1. a solar cell array including a bifacial first solar cell having a shape extending in a first direction, and a bifacial second solar cell arranged alongside the first solar cell in a second direction intersecting the first direction and having a shape extending in the first direction; a first glass substrate covering a first main surface side of the solar cell array; a reflective film disposed at least partially on the second main surface side of the solar cell array, the reflective film having a transmittance higher than a reflectance in the visible light region and a reflectance higher than the transmittance in the near infrared region; and an air layer interposed between the solar cell array and the reflective film. Glass building materials.

2. a distance between the reflective film and the first solar cell is 0.5 times or more a length of the first solar cell in a direction perpendicular to the first direction; The glass building material according to claim 1 .

3. a first reflector facing the second main surface of the first solar cell and extending in the first direction; 3. The glass building material according to claim 1 or 2.

4. a length of the first reflector in a direction perpendicular to the first direction is equal to or greater than a length of the first solar cell in the direction perpendicular to the first direction; The glass building material according to claim 3.

5. The first reflector is disposed on a surface side of the reflector film that does not face the first solar cell. The glass building material according to claim 3.

6. Further comprising a second glass substrate disposed between the first reflector and the reflective film. The glass building material according to claim 5.

7. further comprising a fourth glass substrate disposed between the first reflector and the second glass substrate. The glass building material according to claim 6.

8. Further comprising a fifth glass substrate disposed between the air layer and the reflective film. The glass building material according to claim 6.

9. Further comprising a sixth glass substrate disposed between the fifth glass substrate and the reflective film. The glass building material according to claim 8.

10. Further comprising a third glass substrate interposed between the solar cell array and the air space.

10. A glass building material according to claim 1.

11. Further comprising an encapsulant interposed between the first solar cell and the second solar cell. The glass building material according to any one of claims 1 to 10.

12. The first solar cell has a spectral sensitivity in a wavelength range of at least 300 nm to 1200 nm.

12. A glass building material according to any one of claims 1 to 11.

13. The first solar cell is a heterojunction solar cell. The glass building material according to claim 12.

14. the reflective film reflects at least near-infrared light in sunlight incident from the first main surface side of the first solar cell and causes the light to be incident on the second main surface of the first solar cell.

14. A glass building material according to any one of claims 1 to 13.

15. the reflective film has an uneven surface, and diffusely reflects the near-infrared light so that the near-infrared light is incident on the second main surface of the first solar cell. The glass building material according to claim 14.

16. the first reflector reflects at least a near-infrared component and a visible light component in sunlight incident from the first main surface side of the first solar cell, and causes the sunlight to be incident on the second main surface of the first solar cell; 8. A glass building material according to claim 3.

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