JP2013062398A - Concentrated solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concentrated solar cell module utilizing a light guide technology capable of reducing loss of light under guidance without up-sizing the device, and to provide a concentrated solar cell module capable of maintaining a certain concentration function by reducing the required performance of a sun tracking system, or even when the sun tracking system is not provided.SOLUTION: A concentrated solar cell module 1 comprises: a plurality of condensing means 2 for collecting sun light; a plane waveguide 4 formed in branch shape having a plurality of branches 3, and having a plurality of incident end faces 3a provided, respectively, for the condensing means 2, and at least one emission end face 7 on which sun light incident to the incident end faces 3a is guided while being condensed; and a solar cell element 8 which receives the light emitted from the emission end face 7 and converts the received light into electric power.

Description

  The present invention relates to a concentrating solar cell module that efficiently generates power by concentrating sunlight in a predetermined range and guiding it to a solar cell element.

The importance of solar power generation has been well recognized since the oil shock era of the 1970s. As solar cell elements of solar cell modules used for such photovoltaic power generation, those using single crystal or polycrystalline bulk semiconductor, amorphous silicon, CIGS (Copper
Indium Gallium DiSelenide), which uses thin-film semiconductors, has been put into practical use, but the high manufacturing cost of the device is a drag on the spread. Further, organic solar cells that are advantageous in terms of cost have been actively researched, but there are problems in performance and they have not been put into practical use.

  Therefore, a concentrator photovoltaic system (CPV system) that can reduce the number of solar cell elements by collecting sunlight into a small area solar cell using an optical component such as a lens has high performance. It is attracting attention as a solar cell module that can reduce costs. However, since the concentrating solar cell module collects sunlight at the position of a small area solar cell element, it is necessary to track the sun with high accuracy. Therefore, in many cases, the concentrating solar cell module needs to be provided with a computer-controlled solar tracking system, and this solar tracking system is a factor that increases development cost, manufacturing cost, and installation cost.

  Therefore, in order to further reduce the addition to the solar tracking system and reduce the cost, a concentrating solar cell module using a light guiding technique has attracted attention. As a first example of the concentrating solar cell module 100 using such a light guiding technique, for example, as shown in FIG. 8, a large number of lens elements 101 that condense sunlight L are arranged in parallel. The lens array 102 is provided, the end of the optical fiber-shaped light guide member 103 is disposed at the focal position of each lens element 101 of the lens array 102, and the sunlight L condensed by the lens element 101 is guided. A concentrating solar cell module 100 guided to the solar cell element 104 through the member 103 is cited (Patent Document 1). According to the concentrating solar cell module 100, the sunlight L irradiating the lens array 102 is condensed on the end of the light guide member 103 by each lens element 101 and guided to the solar cell element 104 by the light guide member 103. Therefore, the light collection magnification can be increased, and the small solar cell element 104 can generate power efficiently. In addition, by condensing using the lens array 102 in which a large number of lens elements 101 are arranged in parallel, the weight can be reduced compared to the case where the sunlight L is collected from a large area with one lens. The load on the solar tracking system can be reduced.

  As a second example of the concentrating solar cell module 200 using another light guide technology, a light guide plate 203 is used below a lens array 202 in which a plurality of lens elements 201 are arranged in parallel. A concentrating solar cell module 200 configured by arranging a prism-like reflecting member 204 at a focal position of a lens element 201 of 202 is disclosed (Non-Patent Document 1). According to the concentrating solar cell module 200, the sunlight L collected at the focal point of the lens element 201 is reflected by the reflecting member 204, propagates in the light guide plate 203 in a predetermined direction, repeats total reflection, and is guided. The light enters the solar cell element 205 installed at the end of the light plate 203. Therefore, since the sunlight L irradiated to the lens array 202 can be guided to the solar cell element 205 with a high concentration magnification, it is possible to generate electric power efficiently. In particular, the light guide plate 203 is made extremely thin about several millimeters. Therefore, the concentrating solar cell module 200 can be manufactured extremely thin, and the weight load on the solar tracking system can be reduced.

JP 2005-166704 A Jason H. Karp, Eric J. Tremblay, and Joseph E. Ford, “Planar micro-opticsolar concentrator,” Opt. Express Vol. 18, pp. 1122-1133, 2010

  However, in the concentrating solar cell module 100 of the first example, when the optical fiber-shaped light guide member 103 is bent beyond a predetermined curvature, the light propagating from the bent portion to the outside is exposed to the outside. Leakage of micro-bending loss occurs. Therefore, since it is necessary to suppress the curvature of the light guide member 103 within a predetermined range, there is a limit to reducing the thickness of the concentrating solar cell module 100.

  In the concentrating solar cell module 200 of the second example, since the reflecting member 204 is arranged for each lens element 201 of the lens array 202, the light is condensed by the lens element 201, reflected by the reflecting member 204, and guided. A part of light L ′ propagating through the light plate 203 enters the reflecting member 204 disposed at the focal position of another lens element 201 and leaks outside the light guide plate 203. Since the leaked light becomes a loss that does not contribute to power generation, the reflection member 204 can be provided only in a part of the light guide plate 203 in order to reduce this loss. Therefore, this concentrating solar cell module 200 requires a highly accurate solar tracking system. Moreover, when sunlight L is spread | diffused like a cloudy day etc., since the light condensed on the reflection member 204 reduces, there exists a problem that electric power generation efficiency worsens.

  Accordingly, the present invention provides a concentrating solar cell module that can reduce the loss of light during light guiding without increasing the size of the device in the concentrating solar cell module using the light guiding technology. The purpose is to do. It is another object of the present invention to provide a concentrating solar cell module that can reduce the required performance of the solar tracking system or maintain a certain condensing function even when no solar tracking system is provided.

  The concentrating solar cell module according to claim 1 includes a plurality of condensing means for collecting sunlight, a plurality of branch paths, and a plurality of incident end faces provided for each of the condensing means, A planar waveguide having at least one exit end face that is guided by the light incident on the entrance end face, and a solar cell element that receives the light exiting from the exit end face and converts it into electric power. It is said.

  The concentrating solar cell module according to claim 2 is characterized in that the incident end face converts at least light incident on the incident end face from above into a substantially horizontal direction.

  The concentrating solar cell module according to claim 3, wherein the planar waveguide includes a branching point reflecting means for converting a traveling direction of light into a joining direction of the planar waveguide at a branching point of the planar waveguide. Yes.

  The concentrating solar cell module according to claim 4 is characterized in that an area of the exit end face is smaller than a total area of the plurality of entrance end faces.

  The concentrating solar cell module according to claim 5 is characterized in that a second condensing unit is provided between the condensing unit and the incident end face of the planar waveguide.

  The concentrating solar cell module according to claim 6, wherein the solar cell element includes a plurality of types of elements having different photoelectric conversion characteristics, and has a spectroscopic unit between the emission end face and the solar cell element. It is a feature.

  According to the concentrating solar cell module according to claim 1, the sunlight condensed by the plurality of condensing means can be collected in one solar cell element by the planar waveguide branched into branches. In theory, 100% light utilization efficiency can be achieved by avoiding light loss. Further, by using a plurality of condensing means, the distance from the condensing means to the planar waveguide can be shortened, and the planar waveguide itself can be manufactured extremely thin, so that the concentrating solar cell module The thickness of itself can be made thin and light, and even when a solar tracking system is provided, the weight load can be reduced.

  According to the concentrating solar cell module according to claim 2, the incident end face converts light incident from above into a substantially horizontal direction, so that the concentrating solar cell module can be further thinned.

  According to the concentrating solar cell module according to claim 3, the branch point reflecting means for converting the traveling direction of the light into the joining direction of the planar waveguide is formed at the branch point of the planar waveguide. Can be made simpler and more compact.

  According to the concentrating solar cell module of claim 4, since the area of the exit end face is smaller than the total area of the plurality of incident end faces, the light condensed by the condensing means is further collected by the planar waveguide. Since the light is emitted, the light collecting magnification can be increased, and a more efficient concentrating solar cell module can be obtained.

  According to the concentrating solar cell module according to claim 5, since the second condensing means is provided between the condensing means and the incident end face of the planar waveguide, the concentrating solar cell module is incident on the concentrating solar cell module. Even when the sunlight deviates from the vertical direction of the light receiving surface of the light collecting means, the incident sunlight can be guided to the incident end face of the planar waveguide by the second light collecting means. The accuracy requirement can be reduced. Moreover, since the light incident on the incident end face of the planar waveguide can be increased by the second condensing means, the condensing magnification can be improved.

  According to the concentrating solar cell module according to claim 6, the solar light is separated by wavelength from the spectroscopic means provided between the emission end face and the solar cell element, and is adapted to each photoelectric conversion characteristic. Since the battery element is irradiated, the power generation efficiency can be increased.

The front view explaining the whole structure of the concentrating solar cell module of 1st Embodiment. (A) is an end view obtained by vertically cutting the concentrating solar cell module of the first embodiment, and (B) illustrates that the incident end surface converts light incident from above into a substantially horizontal direction ( A partially enlarged view of A). The partially abbreviated perspective view explaining the light which propagates the inside of a planar waveguide. (A) is a front view explaining the whole structure of the concentrating solar cell module of 2nd Embodiment, (B) is a partially abbreviation enlarged view of (A) explaining the propagation of the light in a branch point. (A) is a front view explaining the whole structure of the concentrating solar cell module of 3rd Embodiment, (B) is a partially abbreviated enlarged view of (A) explaining the propagation of the light in a branch path. . The partial omission perspective view explaining the concentrating solar cell module of 4th Embodiment. The front view explaining the concentrating solar cell module of 5th Embodiment. The perspective view explaining the solar cell module using the conventional light guide technology. Sectional drawing explaining the solar cell module using another conventional light guide technology.

[First Embodiment]
Hereinafter, a first embodiment of a concentrating solar cell module 1 according to the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the concentrating solar cell module 1 according to this embodiment includes a plurality of condensing means 2 for concentrating sunlight L and a plurality of branch paths 3 to generate sunlight L. Receives sunlight L emitted from the planar waveguide 4 to be guided, the support substrate 5 that supports the planar waveguide 4, and the exit end face 7 formed at the end of the planar waveguide 4 on the trunk path 6 side, A solar cell element 8 that converts electric power.

  As shown in FIG. 2A, the light condensing means 2 is a plano-convex lens whose upper surface is flat and whose lower surface protrudes, for example, and whose light receiving part has a square shape. In FIG. 1 (A), the condensing means 2 is shown in a circle by a broken line for easy understanding of the drawing. In this embodiment, for example, sixteen light collecting means 2 in four rows and four rows are formed integrally with a transparent resin to form a lens array 9. By using the lens array 9 in which the condensing means 2 of plano-convex lenses having a flat upper surface in this way are used, it is difficult for dirt to adhere to and accumulate on the upper surface of the lens array 9, and dirt is easily removed. Therefore, it is easy to maintain, and it is possible to suppress a decrease in the light collection efficiency due to contamination on the upper surface of the light collecting means 2. In addition, the material of the condensing means 2 is not limited to this, You may form with materials other than resin, such as glass which transmits light, rubber | gum, and a permeable crystal. In addition, the shape of the light receiving surface of the lens that is the light condensing unit 2 is not limited to a circle, and for example, a shape that can be arranged without gaps between a rectangle and a polygon can be adopted. The condensing means 2 is not limited to a plano-convex lens, and any lens that collects light using refraction such as a Fresnel lens, a biconvex lens, a prism, and a compound lens may be used as long as it can converge parallel light beams. Various optical condensing means 2 such as a reflecting mirror for condensing light by using reflection of a concave mirror or the like can be used.

  The planar waveguide 4 is made of glass having an absolute refractive index of about 1.5, for example, and is manufactured by injection molding using a mold or a semiconductor process. For example, when manufactured by a semiconductor process, fine processing of about several micrometers is possible, and miniaturization of the concentrating solar cell module 1 can be achieved. The support substrate 5 that supports the planar waveguide 4 is formed of a transparent material having a refractive index lower than that of the planar waveguide 4. The support substrate 5 may have any shape as long as it can support the planar waveguide 4.

  As shown in FIG. 1A, the planar waveguide 4 has a plurality of branch paths 3, and these branch paths 3 merge to form a trunk path 6 that guides sunlight L to the solar cell element 8. Has been. Specifically, an intermediate path 13 branched into four at right angles from the main path 6 is formed, and further branched into four branch paths 3 from the intermediate path 13. The tips of these branch paths 3 are respectively arranged on the focal points of the respective light collecting means 2 and serve as a light collecting spot of sunlight L collected by the light collecting means 2. The incident end face 3a for converting the sunlight L incident from the side into a substantially horizontal direction.

  As shown in FIGS. 2A and 2B, the incident end face 3a is formed by inclining the incident end face 3a so that the angle formed by the upper surface of the branch path 3 and the incident end face 3a is approximately 45 degrees. The sunlight L collected through the condensing means 2 from above enters the planar waveguide 4 from the upper surface of the branching path 3, and enters the branching path 3 from the inside of the planar waveguide 4. When incident on the incident end face 3 a, the sunlight L is totally reflected at an almost right angle at the interface of the planar waveguide 4 and propagates in the branch path 3. When the absolute refractive index of the planar waveguide 4 is about 1.5, the critical angle from the planar waveguide 4 to air is about 42 degrees, and the sunlight L incident from a direction orthogonal to the upper surface of the branch path 3 is. Is incident at an incident angle of 45 degrees with respect to the incident end face 3a, so that it is totally reflected. Thus, the incident angle of the sunlight L with respect to the incident end face 3a of the branch path 3 is preferably equal to or greater than the critical angle in order to efficiently propagate the sunlight L, and is incident on the outermost edge of the light collecting means 2. Even if it is sunlight L, the condensing means 2 of the focal distance and light-receiving area which can satisfy | fill this condition is selected. In addition, you may form the incident end surface 3a so that sunlight L can be reflected, for example by aluminum vapor deposition.

  Further, as shown in FIGS. 1 and 3, the planar waveguide 4 converts the traveling direction of the sunlight L that has propagated through the branch path 3 into a junction direction at a branch point 11 where the branch path 3 joins. A branch point reflecting means 12 is provided. This branch point reflecting means 12 is formed by cutting out the branch point 11 of the planar waveguide 4 so that the interface between the planar waveguide 4 and air is approximately 45 degrees with respect to the longitudinal direction of the branch path 3. Is. The sunlight L that has propagated through the branch path 3 of the planar waveguide 4 is totally reflected by the branch point reflecting means 12 and its path is converted to a right angle. Then, the sunlight L propagating through the planar waveguide 4 reaches the trunk path 6 and enters the solar cell element 8 installed on the exit end face 7 of the trunk path 6.

  The size of each part is, for example, that the condensing means 2 is a square with a side of 3 millimeters, and the condensing spot is placed above the planar waveguide 4 at a predetermined distance so that one side is 80 micrometers. Yes. The planar waveguide 4 has a height of, for example, 100 micrometers and the branch path 3 has a width of 100 micrometers. The width of the intermediate path 13 at the position where the two branch paths 3 merge is formed to be 200 micrometers, and the width of the trunk path 6 where all 16 branch paths 3 merge is 1.6 mm. It is millimeter. Therefore, the area in which the lens array 9 formed by arranging the 16 condensing means 2 receives the sunlight L is 144 mm, and the exit end surface 7 formed at the end of the trunk path 6 has a width of Since it is 1.6 millimeters and the height is 100 micrometers, it is 0.16 millimeters, and the condensing magnification is 900 times.

  As described above, according to the concentrating solar cell module 1 of the present embodiment, the sunlight L collected by the condensing means 2 is totally reflected by the incident end face 3 a and is branched into the branch path 3 of the planar waveguide 4. Propagating, totally reflected by the branching point reflecting means 12 at the branching point 11 where the branching path 3 joins, is transmitted to the main path 6, and enters the solar cell element 8 from the emission end face 7. Even if the incident angle of the sunlight L deviates from the normal direction at the interface of the planar waveguide 4, the sunlight L does not leak to the outside as long as the condition of total reflection is satisfied, and the solar cell element 8 is extremely efficient. Sunlight L can be collected.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. In the present embodiment, as shown in FIG. 6A, the lens array 9 is formed by arranging the condensing means 2 in a hexagonal manner. By arranging in this way, the circular arrangement can be arranged with the highest density, so that light can be collected efficiently.

  Further, the planar waveguide 4 in this embodiment is formed with a branch point reflecting means 12 by notching a surface side opposite to the joining direction at the branch point 11 of the branch path 3, and this branch point reflecting means 12 is formed. The sunlight L incident on the interface is totally reflected and the course is changed at a right angle. An inclined surface 14 is formed on the surface facing the branch point reflecting means 12 so that the width of the planar waveguide 4 becomes narrower in the merging direction. By forming such an inclined surface 14, the sunlight L totally reflected by the branch point reflecting means 12 is further totally reflected by the inclined surface 14 and merges into the main road 6 side. There is no need to increase the width of the trunk 6 on the element 8 side. Therefore, the area of the exit end face 7 can be kept small, so that the light collecting magnification can be further increased.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment and 2nd Embodiment, and description is abbreviate | omitted. As shown in FIG. 5A, the planar waveguide 4 in the present embodiment is formed by bending the branch path 3 with a predetermined curvature. When formed in this way, the sunlight L propagating through the planar waveguide 4 is formed as shown in FIG. 5B without providing the notch at the branch point 11 to form the branch point reflecting means 12. The direction can be changed to the merging direction, and since it is not necessary to increase the width of the planar waveguide 4 on the solar cell element 8 side, the light collecting magnification is excellent. In addition, the loss of the sunlight L during light guide can be suppressed by setting the curvature of the branch path 3 within a range in which the microbending loss does not occur.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to 1st Embodiment to 3rd Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. The concentrating solar cell module 1 of this embodiment further includes a second condensing unit 15 between the condensing unit 2 and the incident end face 3 a of the planar waveguide 4. In FIG. 6, for convenience of illustration, the description of the light collecting means 2 is omitted, but the light collecting means 2 is formed on the second light collecting means 15. This second condensing means 15 is a plano-convex lens formed on a parabolic surface whose upper surface is flat and whose lower surface protrudes greatly, and totally reflects sunlight L incident from the upper surface at the interface of the lower surface, It is led to the incident end face 3a of the planar waveguide 4. If comprised in this way, even if it is incident on the 2nd condensing means 15 even if it has entered into the 2nd condensing means 15 even if the sunlight L which shifted from the orthogonal | vertical direction with respect to the upper surface of the condensing means 2, it will enter into the entrance end surface 3a of the planar waveguide 4. Therefore, the allowable angle of sunlight L is widened, and the demand for accuracy of the solar tracking system can be reduced. Such a second light condensing means 15 can be added to any of the first to third embodiments described above.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to 1st Embodiment to 4th Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. The concentrating solar cell module 1 of this embodiment includes two or more solar cell elements 8 a and 8 b having different photoelectric conversion characteristics, and these solar cell elements 8 a and 8 b and the emission end face 7 of the planar waveguide 4. A spectroscopic unit 18 including a convex lens 16 and a transmission type diffraction element 17 is provided between the projection unit 16 and the projection unit 16. The convex lens 16 converts a divergent light beam emitted from the exit end face 7 of the planar waveguide 4 into a parallel light beam. Then, the parallel light beam passes through the transmission type diffraction element 17 and is dispersed, and is incident on the solar cell elements 8a and 8b having conversion characteristics matching the respective wavelengths. The spectroscopic means 18 is not limited to the diffraction element 17, and a prism or the like may be combined. By using the solar cell element 8 having conversion characteristics suitable for each wavelength of light, the power generation efficiency of the concentrating solar cell module 1 can be made higher.

  Needless to say, the embodiment of the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the scope of the idea of the present invention.

  The concentrating solar cell module 1 according to the present invention can be suitably used as the concentrating solar cell module 1 installed on the roof or roof of a building.

DESCRIPTION OF SYMBOLS 1 Solar cell module 2 Condensing means 3 Branching path 4 Planar waveguide 7 Outgoing end surface 8 Solar cell element 11 Branch point 12 Branch point reflection means 15 2nd condensing means 18 Spectroscopic means

Claims (6)

A plurality of light collecting means for collecting sunlight;
A plurality of branch paths formed, a plurality of incident end faces provided for each of the light collecting means, and a planar waveguide having at least one exit end face that is guided by the light incident on the incident end faces;
A solar cell element that converts light emitted from the emission end face into electric power;
A concentrating solar cell module comprising:   2. The concentrating solar cell module according to claim 1, wherein the incident end face converts at least light incident on the incident end face from above into a substantially horizontal direction.   3. The condensing type according to claim 1, wherein the planar waveguide is provided with a branching point reflecting unit that converts a traveling direction of light into a merging direction of the planar waveguide at a branching point thereof. Solar cell module.   4. The concentrating solar cell module according to claim 1, wherein an area of the exit end face is smaller than a total area of the plurality of entrance end faces.   5. The concentrating solar cell according to claim 1, further comprising a second condensing unit between the condensing unit and the incident end face of the planar waveguide. module. The solar cell element includes a plurality of types of elements having different photoelectric conversion characteristics,
The concentrating solar cell module according to any one of claims 1 to 5, further comprising a spectroscopic unit between the emission end face and the solar cell element.

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