JPH09260705A - Natural lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of partial shadows and increase an amount of natural lighting when light is incident from a low altitude, by using a nearly dome-like translucent surface coating material to cover a natural lighting port and making the surface coating material in such a structure that a part of a side wall which is near a solar battery can bend incident light more strongly toward the solar battery side than a part which is away from the natural lighting port. SOLUTION: As for a surface coating material 5, a nearly dome-like material which has a shape of a turned-over bowl is used. The surface coating material 5 has a side wall section 5a and a ceiling section 5b which has a peak at the center. An inner face of the side wall section 5a stretches linearly in the circumferential direction and has a face of a Fresnel lens, with steps formed in the up and down direction, by which the incident light can be bent toward the solar battery 2 side. The Fresnel lens has such a structure that a part which is near a solar battery can bend incident light more strongly than a part which is away from the solar battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a daylighting device such as a solar cell device, a skylight, etc., in which a daylighting port is covered with a light-transmitting surface coating material.

[0002]

2. Description of the Related Art Some road signs, signboards, and gate lights for nighttime display use a solar cell system that supplies DC power generated from a solar cell device to a storage battery and a load via a backflow prevention diode. .

FIG. 4 is a sectional view showing the structure of a conventional solar cell device used in this type of solar cell system, in which a solar cell 2 and a surface coating material 3 for the solar cell 2 are housed in a case 1 whose top is open. ing. In this case, the solar cell 2 has a plurality of solar cell elements connected in parallel or in series, the surface coating material 3 avoids the influence of moisture and dust, and also withstands collisions such as hailstones and pebbles or wind pressure. The solar cell 2 is enclosed together with the case 1 and sunlight is allowed to pass through. Therefore, a glass plate is used as the surface covering material 3, and a glass plate, a resin plate or a metal plate (Al, stainless steel, etc.) is used as the case 1.

[0004]

The conventional solar cell device described above has a structure in which there are few voids between the solar cell 2 and the surface coating material 3 and they are in close contact with each other. The sine of the incident altitude of sunlight and the solar cell 2
It is said to be proportional to the surface area of. Therefore, when the incident altitude is low, the incident amount is small. On the other hand, the surface covering material 3 is formed to be relatively thick because it is necessary to protect the solar cell 2. Further, the upper edge portion of the case 1 is provided with the surface coating material 3
It is bent with an appropriate width inside so as to press down the periphery of. Therefore, the sunlight altitude θ is, for example,
When incident at a low altitude of 15 degrees or less, the upper edge 1a of the case 1 causes a partial shadow 4 on the surface of the solar cell 2 even if sunlight in the range of the illustrated width W contributes to power generation. Even if the partial shadow 4 is several tenths of the surface of the solar cell, the output may drop to half or less.
The reason will be described below with reference to FIG.

The solar cell 2 is, as shown in FIG.
Terminal 2 by connecting a plurality of solar cell elements 11 to 1n in parallel
DC current is taken out from 1, 2 or FIG.
As shown in (b), a plurality of solar cell elements 11 to 1n are connected in series to draw a direct current from the terminals 21 and 22.

As is well known, although not shown, the solar cell element includes a photovoltaic generator, a diode for passing a forward current by a forward bias generated by light, and a resistor due to a pn junction defect. It is represented by an equivalent circuit connected in parallel. Now, when the partial shadow 4 occurs on the solar cell element 12 shown in FIG. 5A, the solar cell element 12 itself does not generate an electromotive force, and the other solar cell elements 11, 13 to 1n
The leakage currents i11, i13 to i1n are caused by the electromotive force of and the output current i is extremely reduced. FIG. 5 (b)
When the partial shadow 4 appears on the solar cell element 12 shown in
The resistance value of the solar cell element 12 itself increases and the output current i
Results in a small aperture.

Incidentally, if the current i and the voltage v have the relationship shown by the characteristic curve A in FIG. 5 (c) in the absence of partial shadows, a partial shadow is generated in one of the solar cell elements connected in parallel. In the case where the solar cell elements are connected in series, a direct current output decreases as shown in the characteristic curve B. The output will decrease.

The decrease in output due to the partial shadow described above means that the storage battery of the solar cell system is not normally charged,
It may adversely affect the entire system.

Further, in a daylighting device such as a skylight, there is a problem that a partial shadow is generated by the frame body of the daylighting port and incident light is reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a solar cell device capable of slightly suppressing a decrease in output characteristics even for incident light at a low altitude. And

[0011]

In the conventional solar cell device shown in FIG. 4, the upper edge portion 1a of the case 1 produces a partial shadow 4 on the surface portion of the solar cell 2 against low altitude sunlight. I was letting it.

The present invention not only suppresses the generation of this partial shadow but also increases the amount of light incident on the lighting port. Therefore, the surface coating material having a light-transmitting property for covering the lighting port is almost A dome-shaped one is used, and the side wall part is configured to strongly refract the incident light toward the lighting side rather than the part farther from the lighting side than the further part.
As a result, while suppressing the generation of partial shadows, the incident light amount of low-altitude sunlight to the lighting entrance is increased, and in some cases, it is possible to use incident light with a horizontal or negative altitude as seen from the lighting entrance. I am trying. Here, it is preferable that the side wall portion of the surface coating material be a Fresnel lens in order to reduce the cost. However, when the Fresnel lens is used, a step for changing the refraction angle is generated, and a part with a small amount of light is formed at the boundary, which may cause uneven illuminance. Therefore, the surface coating material has a shape in which the inner surface portion scatters and radiates the incident light, or the material itself has a property that scatters and radiates the incident light to eliminate the unevenness of illuminance.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the drawings.

FIG. 1 is a sectional view showing the structure of the first embodiment of the present invention. In the figure, the same elements as those in FIG. 4 showing the conventional apparatus are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, instead of the flat plate-like surface covering material 3 in FIG. 4, a substantially dome-like surface covering material 5 having a bowl shape is used. With this, between the solar cell and the surface coating material, the other opposing surfaces can be seen through and the partial shadow can be prevented.

Further, the surface coating material 5 has a side wall portion 5a.
And a ceiling portion 5b having a central portion as an apex.
Of these, the inner surface of the side wall portion 5a is linearly continuous in the circumferential direction,
The Fresnel lens surface has a step in the vertical direction, and has a structure in which incident light is refracted toward the solar cell 2 side.

The Fresnel lens surface has an angle at which the incident light is strongly refracted toward the solar cell side at a portion closer to the solar cell than at a portion farther from this. Therefore, the sunlight having the width of W shown in the figure goes to the solar cell 2 as shown by the solid line, and the effective incident angle increases as compared with the conventional device. In addition, the incident light in the horizontal direction indicated by the broken arrow X,
Since the incident light of negative altitude indicated by the dashed arrow Y is also refracted to the solar cell side, these incident light can also be used for power generation.

On the other hand, the ceiling portion 5b has a shape in which the central portion is raised with a substantially constant thickness. This is because there is no need to intentionally increase the amount of incident light because the intensity of solar radiation at high altitudes is high. It should be noted that by forming the mountain shape so that the central portion becomes the apex, it is difficult to attach the leaves of trees or bird droppings that form a partial shadow to the solar cell. This is also effective in that the maintenance and inspection accompanied by periodic wiping of the surface portion of the surface coating material 5 becomes unnecessary or easy.

The Fresnel lens surface has a step for changing the refraction angle, and a portion with a small amount of light is formed at the boundary, which causes uneven illuminance on the surface of the solar cell. This can be solved by using a member containing fine bubbles or fine scattering particles, or by making the inner surface matte.

FIG. 2 is a characteristic diagram showing the relationship between the incident altitude θ of sunlight and the incident light amount I. In general, when it is covered with a flat plate glass, the sunlight having a width W1 covers the surface of the solar cell 2. As shown by the curve P after irradiation, the incident amount is I1. However, in the present embodiment, since the incident light is refracted toward the solar cell side, sunlight of width W2 irradiates the surface of the solar cell 2,
As shown by the curve Q, the incident amount increases to I2.

Thus, according to the first embodiment shown in FIG. 1, the influence of the side wall 5a being a refraction member is small with respect to incident light at a high altitude, and there is no great difference from the conventional device. The characteristics can be maintained and the characteristics in the morning and evening can be greatly improved.

When the weather is bad, power is generated not by direct solar radiation from the sun but by scattered solar radiation scattered by molecules and snow in the atmosphere.

The first embodiment receives scattered solar radiation from the entire sky, and since the amount of incidence on the solar cell 2 is increased over the entire periphery of the surface coating material 5, the amount of power generation during bad weather is also increased. There is also an effect that can be increased.

FIG. 3 is a sectional view showing the structure of the second embodiment of the present invention. In the figure, the same elements as those of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, a dome-shaped surface covering material 6 whose overall shape is substantially the same as that of FIG. 1 is used. However, the surface coating material 6 is different from the surface coating material 5 of FIG. 1 in the shape of the side wall portion 6a. That is, the side wall portion 6 a of the surface coating material 6 has a large wall thickness in a portion close to the solar cell 2, and the wall thickness becomes smaller as it is separated from the solar cell 2.

In this case, the low-altitude sunlight causes the surface coating 6
The light rays are skillfully used to refract in the thick direction when passing through the side wall portion 6a of the solar cell. , Thickness and curvature are determined.

As a result, as described with reference to the characteristic diagram of FIG. 2, among the sunlight having an incident altitude of θ, the incident amount in the conventional device was only I1 in the present embodiment. The amount becomes I2, and the amount of power generation also increases.

Also in the second embodiment, since the ceiling 6b has a shape in which the central portion is raised with a substantially constant thickness, the leaves of the trees and bird droppings that form a partial shadow are attached to the solar cell. Making it difficult. Therefore, there is also an effect that maintenance and inspection accompanied by periodic wiping of the surface portion of the surface covering material 5 become unnecessary or facilitated.

Even in this case, when there is a possibility that a light-shielding object is attached to the surface of the surface coating material 6, the scattering of the multi-lens surface or the multi-prism surface over the entire inner surface of the surface coating material 6. By making it a radiation surface,
The surface of the solar cell 2 can be evenly illuminated. Further, the surface coating material is not limited to the multi-lens surface or the multi-prism surface, and a surface coating material made of a member containing fine bubbles or irregularities or fine scattering particles or scratches may be used.

The daylighting device of the present invention is not limited to a solar cell device in which a solar cell is provided in the daylighting port, but is also applicable to a daylighting device such as a skylight for taking sunlight into the room from the daylighting port. It goes without saying that it is possible.

[0031]

As is apparent from the above description, according to the present invention, as the translucent surface covering material for covering the lighting port, a material having a substantially dome shape is used, and the side wall portion thereof is Since the part near the lighting port is configured to refract the incident light toward the lighting port more strongly than the part far from it, it suppresses the generation of partial shadows and suppresses the decrease of the incident light, and at the same time, it can The amount of light can be increased.

Further, as the surface coating material, the inner surface of the solar cell has a shape that scatters and radiates incident light, or a material itself has a property of scatter and radiate incident light. It is possible to maintain power generation efficiency and increase the amount of morning and evening lighting in a lighting device such as a skylight.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the incident angle of sunlight and the amount of incident light in order to explain the operation of the first embodiment shown in FIG.

FIG. 3 is a sectional view illustrating a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a conventional solar cell device.

FIG. 5 is an explanatory diagram for explaining a detailed configuration of a conventional solar cell device and an influence of a partial shadow.

[Explanation of symbols]

 2 solar cell (lighting port) 3 surface coating material 4 partial shadow 5,6 surface coating material 5a, 6a side wall portions 5b, 5b ceiling portion 11 to 1n solar cell element

Claims (4)

[Claims] 1. In a daylighting device in which a light-transmissive surface covering material covers the lighting opening, the surface covering material is formed in a substantially dome shape, and the surface covering material has a portion close to the lighting opening. A daylighting device comprising a side wall portion that strongly refracts incident light toward a light collecting port side rather than a distant portion. 2. In a daylighting device in which a light-transmitting surface covering material covers the lighting opening, the surface covering material is formed in a substantially dome shape, and the surface covering material has a portion close to the lighting opening. A daylighting device comprising a side wall portion that strongly refracts incident light toward a light collecting port side than a distant portion, and the surface covering material has a shape in which an inner surface portion scatters and emits the incident light. 3. In a daylighting device in which a light-transmitting surface covering material covers the lighting opening, the surface covering material is formed in a substantially dome shape, and the surface covering material has a portion close to the lighting opening. A daylighting device comprising a side wall portion that strongly refracts incident light toward a light collecting port side than a distant portion, and the surface covering material itself has a shape that scatters and emits incident light. 4. The daylighting device according to claim 1, wherein the daylighting port is provided with a solar cell.