JP2005285948A - Solar cell module and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module which can raise light condensing efficiency by lowering the reflectivity on the surface of the solar battery so as to take in sunlight sufficiently. <P>SOLUTION: The solar cell module includes a solar battery 10, and an optical element 1 arranged at the surface 10a side of the solar battery 10. The optical element 1 includes a lens 2 arranged at the incidence side of sunlight, and a trapezoidal prism 4 arranged at the solar battery 10 side. Furthermore, sunlight is made refracted twice by the light condensing operation of the lens 2 and the refraction operation of the trapezoidal prism 4, so that the incident angle of the sunlight which enters into the surface 10a of the solar battery 10 may be made small. Thus, the light condensing efficiency can be raised since the reflectivity in the surface 10a of the solar battery 10 is lowered, and sunlight can be taken in efficiently. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to, for example, a concentrating solar cell module that increases conversion efficiency and a method for manufacturing the same.

  Solar cells that use solar energy are expected to be used as a clean energy source in a wide range from households to power plants. In order to increase the light collection efficiency of the solar cell, it is necessary to prevent the sunlight incident on the solar cell from being reflected on the surface of the solar cell and efficiently confine it. For this purpose, it is important to place the light-receiving portion on the surface of the solar cell at a position substantially perpendicular to the incidence of sunlight and reduce the reflectance on the surface. However, solar cells are usually fixed in many cases and cannot cope with changes in the incident angle depending on the solar time or season. Therefore, with respect to sunlight incident from an oblique direction, there is a problem that the reflection loss increases and the light collection efficiency cannot be increased. In general, the absorptance of a solar cell drops sharply when the incident angle with respect to the solar cell is 60 ° or more, and the reflectance increases.

  Therefore, as a means for improving the above problem, a solar cell in which a solar tracking device is incorporated so that the surface of the solar cell is always perpendicular to the sun has been proposed, but the device is very expensive. The overall cost is high and it is not economical.

  On the other hand, as disclosed in JP-A-6-37344 (Patent Document 1) and JP-A-8-330619 (Patent Document 2), a solar cell with a collector has been proposed. According to this solar cell with a concentrator, it is possible to take in sunlight that has entered from a wider range than the solar cell by the condensing action of the condensing lens. For this reason, even if it is a case where a solar cell is fixed, the range which can take in sunlight can be enlarged, and cost efficiency can be improved.

However, in the solar cell with a concentrator, since the sunlight is incident on the solar cell only with the condenser lens, there is a limit to the incident angle with respect to the solar cell, and the sunlight incident from an oblique direction is reflected. There is a problem in that the loss increases and the light collection efficiency cannot be increased. In addition, it is necessary to form the refracting surface of the condenser lens strictly, and it is time-consuming to manufacture the condenser lens.
JP-A-6-37344 JP-A-8-330619

  Then, the subject of this invention is providing the solar cell module which can reduce the reflectance in the solar cell surface, can take in sunlight efficiently, and can improve condensing efficiency.

In order to solve the above problems, the solar cell module of the present invention is
Solar cells,
An optical element disposed on the surface side of the solar cell and transmitting sunlight;
This optical element is
A lens disposed on the sunlight incident side and having a refracting surface facing the sunlight incident side;
And a refractive element that is disposed on the solar cell side and has a refractive surface facing the solar cell side.

  According to the solar cell module of the present invention, since the optical element includes the lens and the refractive element, sunlight is refracted at least twice by the condensing action of the lens and the refractive action of the refractive element. Can do. Thus, even if the incident angle of sunlight incident on the solar cell module is large, the incident angle of sunlight incident on the surface of the solar cell is reduced by the optical element, and the surface of the solar cell is reduced. The reflectance can be reduced, sunlight can be efficiently taken in, and the light collection efficiency can be improved.

  Further, since the lens and the refractive element are separate, the optical element having a desired shape and properties can be easily manufactured by combining different types of the lens and the refractive element. In addition, since the sunlight is refracted by the lens and the refractive element, it is not necessary to strictly form the shape of each refractive surface of the lens and the refractive element. In addition, since the refractive surface of the lens and the refractive surface of the refractive element face each other, the lens and the refractive element can be attached to each other back to back. The element can be downsized.

  Moreover, in the solar cell module of one Embodiment, the optical axis of the said lens and the optical axis of the said refractive element correspond.

  According to the solar cell module of this embodiment, since the optical axis of the lens and the optical axis of the refractive element coincide with each other, vignetting of light between the lens and the refractive element occurs. Instead, all the parallel luminous flux (sunlight) incident on the lens can be incident on the refractive element.

  Moreover, in the solar cell module of one Embodiment, the said lens and the said refractive element are arranged in matrix form.

  According to the solar cell module of this embodiment, since the lens and the refractive element are arranged in a matrix, the plurality of lenses and the plurality of refractive elements can be densely arranged. Regardless of the arrangement direction of the lens and the refractive element, light can be collected efficiently throughout the year.

  In one embodiment, the refractive element is a trapezoidal prism, a spherical lens, or a cylindrical lens.

  In one embodiment, the optical element further includes a covering member having a predetermined refractive index on the sunlight incident side of the lens.

  According to the solar cell module of this embodiment, the incident angle range of sunlight that can be taken into the optical element can be widened by providing the covering member having a predetermined refractive index on the lens. Therefore, the range of incident angles on the surface of the solar cell is widened, and the light collection efficiency can be increased. In addition, the covering member plays a role of protecting the lens and can prevent damage to the lens.

  Moreover, in the solar cell module of one Embodiment, the surface of the incident side of the said covering member is flat.

  According to the solar cell module of this embodiment, since the surface of the covering member is flat, sunlight can be reliably refracted and guided to the lens.

Moreover, in the solar cell module of one embodiment,
The angle θ formed between the incident light entering the lens from the intersection of the optical axis of the lens and the refractive surface of the lens and the optical axis of the lens is
The length of the lens and the refractive element in the direction perpendicular to the optical axis of the lens in a plane formed by the incident light and the optical axis of the lens is L,
When the distance between the intersection between the optical axis of the lens and the refractive surface of the lens and the intersection between the optical axis of the refractive element and the surface of the refractive element on the solar cell side is H,
tanθ ≦ 0.5L / H
Meet.

  According to the solar cell module of this embodiment, when it is desired to obtain sunlight incident on the optical element at a desired angle, the optical element has a length L and a distance H that satisfy tan θ ≦ 0.5 L / H. The desired optical element can be reliably obtained.

Moreover, the manufacturing method of the solar cell module of the present invention is as follows:
Attaching the lens to one side of the substrate;
Applying a photosensitive material to the other surface of the substrate;
A step of making light from a light source incident on the lens as parallel light having a uniform light intensity distribution, condensing the light on the photosensitive material by the lens, and forming a refractive element;
A step of disposing the refractive element on the surface side of the solar cell.

  According to the method for manufacturing a solar cell module of the present invention, since the refractive element is manufactured using the lens, the optical axis of the lens and the optical axis of the refractive element can be matched. For this reason, the vignetting of the light between the said lens and the said refractive element does not generate | occur | produce, but all the parallel light beams (sunlight) which injected into the said lens can be incident on the said refractive element. Therefore, a solar cell module with high light collection efficiency can be realized.

  According to the solar cell module of the present invention, the optical element includes the lens and the refractive element. Therefore, even if the incident angle of sunlight is large, the optical element has a condensing function of the lens and a refractive action of the refractive element. The incident angle of sunlight incident on the surface of the solar cell can be reduced, the reflectance on the surface of the solar cell can be reduced, sunlight can be taken in efficiently, and the light collection efficiency can be improved. .

  Further, according to the method for manufacturing a solar cell module of the present invention, since the refractive element is produced using the lens, the optical axis of the lens and the optical axis of the refractive element can be matched, No vignetting of light between the lens and the refraction element, and all the sunlight incident on the lens can be incident on the refraction element, realizing a high concentration efficiency solar cell module it can.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1: has shown the perspective view which is one Embodiment of the solar cell module of this invention. FIG. 2 shows a partial configuration diagram of the solar cell module of the present invention. As shown in FIGS. 1 and 2, this solar cell module includes a solar cell 10 and an optical element 1 that is disposed on the surface 10 a side of the solar cell 10 and transmits sunlight.

  The solar battery 10 includes, for example, a gantry and solar cells attached to the gantry.

  The optical element 1 is made of a material transparent to sunlight, and includes a substrate 7, a lens 2 disposed on one surface of the substrate 7 on the sunlight incident side indicated by an arrow A, and the substrate 7. On the other side, it includes the refractive element 4 disposed on the solar cell 10 side.

  The lens 2 has a refracting surface 20 facing the sunlight incident side. Specifically, the lens 2 is a convex lens, and the convex surface of the convex lens is arranged on the incident side of the sunlight. The mounting surface 21 of the lens 2 with the substrate 7 is rectangular.

  The refractive element 4 has a refractive surface 40 facing the solar cell 10 side. Specifically, the refractive element 4 is a trapezoidal prism, and the refractive surface of the trapezoidal prism is disposed on the solar cell 10 side. The attachment surface 41 of the refraction element 4 with the substrate 7 is rectangular.

  The attachment surface 41 of the refractive element 4 and the attachment surface 21 of the lens 2 have the same size and face each other. The optical axis 22 of the lens 2 and the optical axis 42 of the refractive element 4 are coincident.

  The lens 2 and the refractive element 4 are arranged in a matrix. A plurality of the lenses 2 constitute a lens array 3, and a plurality of the refraction elements 4 constitute a refraction element array 5. At this time, the adjacent lenses 2 and 2 and the adjacent refractive elements 4 and 4 may be connected integrally or may be separate.

  The optical element 1 further includes a covering member 6 having a predetermined refractive index on the sunlight incident side of the lens 2. The surface 6a on the sunlight incident side of the covering member 6 is flat. The covering member 6 includes, for example, a low refractive index resin and is filled between the adjacent lenses 2 and 2 to flatten the surface of the optical element 1.

  Here, since sunlight can be regarded as being at an infinite distance from the solar cell 10, sunlight incident on the optical element 1 can be regarded as a parallel light flux. Hereinafter, sunlight incident on the optical element 1 is expressed as a parallel light flux.

  Next, the operation and effect of the solar cell module having the above configuration will be described with reference to FIG.

  In FIG. 3, description will be made using one lens 2 and one refractive element (trapezoidal prism) 4. Here, the purpose of the function of the optical element 1 is to reduce the reflection loss energy by suppressing the parallel light beam incident on the surface of the solar cell module at an incident angle of 60 ° or more within 60 ° by the optical element 1. In other words, all the parallel light beams can be taken into the solar cell.

The parallel light beam 12 incident on the optical element 1 at an incident angle θ ₁ is bent by the covering member 6 having a predetermined refractive index, and the incident angle θ ₂ is incident on the refractive surface 20 of the lens _2. Incident at. Thereafter, the light is emitted from the refracting surface 20 of the lens 2 at an exit angle θ ₃ by the condensing action of the lens 2 and is incident on the refracting surface 40 of the refractive element 4 at an incident angle θ ₄ . Due to the refraction action of the refraction element 4, the light is emitted from the refraction surface 40 of the refraction element 4 at an emission angle θ ₅ and is incident on the surface 10 a of the solar cell 10 at an incident angle θ ₆ . Here, the said incident angle means the angle which the said parallel light beam 12 and the direction perpendicular | vertical to the surface into which this parallel light beam 12 injects.

Then, an angle θ formed between incident light (parallel light beam 12) incident on the lens 2 from the intersection of the optical axis 22 of the lens 2 and the refractive surface 20 of the lens 2 and the optical axis 22 of the lens 2. ₃ is
In the plane formed by the incident light and the optical axis 22 of the lens 2, the lens 2 (the mounting surface 21) and the refractive element 4 (the mounting surface 41) in a direction perpendicular to the optical axis 22 of the lens 2. ) Is L,
The distance between the intersection of the optical axis 22 of the lens 2 and the refractive surface 20 of the lens 2 and the intersection of the optical axis 42 of the refractive element 4 and the surface of the refractive element 4 on the solar cell 10 side is expressed as follows. If H,
tan θ ₃ ≦ 0.5 L / H (Formula 1)
Meet.

  In short, the incident angle range of the parallel light beam 12 that can be taken into the optical element 1 is expressed as (Equation 1) using L and H. In FIG. 3, since the optical element 1 is symmetric about the optical axes 22 and 42, a range in only one direction is shown.

Refractive index n ₂ of the cover member 6 is 1.45, the lens 2, a refractive index n ₃ of the refractive element 4 and the substrate 7 are the 1.59, between theta ₁ and theta ₂ And between θ ₂ and θ ₃
n ₁ sin θ ₁ = n ₂ sin θ ₂ (Expression 2)
n ₂ sin θ ₂ = n ₃ sin θ ₃ (Equation 3)
The relationship holds. Here, the refractive index n ₁ in the air is 1.

For example, if θ ₁ is 80 °, θ ₂ is 42.8 °, and the incident angle θ ₃ incident into the lens 2 is 38.2 °. Therefore, in order to capture the parallel light beam 12 incident at an incident angle θ ₁ of 80 ° into the optical element 1, the above-described lens 2 that satisfies the ratio of 1.6 ≦ L / H and the above-described formula (1). The optical element 1 may be designed with the length L of the refractive element 4 and the height H of the total of the lens 2 and the refractive element 4.

Thereafter, the light enters the refractive surface 40 of the refractive element 4 at an incident angle θ ₄ . Here, since the angle of incidence of the refracting surface 40 of the refractive element 4 is 45 °, θ ₄ is 6.8 °.

The exit angle θ ₅ from the refractive element 4 is
n ₃ sin θ ₄ = n ₁ sin θ ₅ (Expression 4)
Therefore, θ ₅ is 10.8 ° and is incident on the surface 10a of the solar cell 10. Since the surface 10a of the solar cell 10 is arranged in parallel with the optical element 1, the incident angle θ ₆ incident on the surface 10a of the solar cell 10 takes into account the angle of incidence 45 ° of the refractive element 4. And 34.2 °. That is, the angle of the parallel light beam 12 incident at an incident angle of 80 ° can be made 34.2 ° by the optical element 1 and can be incident on the surface 10 a of the solar cell 10.

  Thus, according to the solar cell module having the above-described configuration, the optical element 1 is used as a surface layer portion of the solar cell module, so that it is incident on the surface of the solar cell module at an incident angle of 60 ° or more. The parallel light flux 12 in the range can be converted so as to be incident on the surface 10a of the solar cell 10 at 60 ° or less. Therefore, the reflectance at the surface 10a of the solar cell 10 can be lowered, sunlight can be taken in efficiently, and the light collection efficiency can be improved.

  In short, since the optical element 1 includes the lens 2 and the refraction element 4, sunlight can be refracted at least twice by the condensing action of the lens 2 and the refraction action of the refraction element 4. That is, the solar cell module of the present invention can be said to be a concentrating solar cell module using a concentrator composed of the lens array 3 and the refractive element array 5.

  Further, since the lens 2 and the refractive element 4 are separate, the optical element 1 having a desired shape and properties can be easily obtained by combining different types of the lens 2 and the refractive element 4. Can be manufactured. Further, since the sunlight is refracted by the lens 2 and the refraction element 4, it is not necessary to strictly form the shapes of the refraction surfaces 20 and 40 of the lens 2 and the refraction element 4. 2 and the refractive element 4 can be easily manufactured. Further, the refractive surface 20 of the lens 2 and the refractive surface 40 of the refractive element 4 face the outside, so that the lens 2 and the refractive element 4 4 can be attached together back to back, and the optical element 1 can be miniaturized.

  Further, since the optical axis 22 of the lens 2 and the optical axis 42 of the refraction element 4 coincide with each other, vignetting of the light beam between the lens 2 and the refraction element 4 does not occur. All the parallel light beams 12 incident on the lens 2 can be incident on the refractive element 4.

  Further, since the lens 2 and the refraction element 4 are arranged in a matrix, a plurality of the lenses 2 and the refraction element 4 can be densely arranged. Regardless of the arrangement direction of 4, the light can be collected efficiently throughout the year.

  Further, by providing the covering member 6, the incident angle range of sunlight that can be taken into the optical element 1 can be widened, and the light collection efficiency can be increased. Further, the covering member 6 serves to protect the lens 2 and can prevent the lens 2 from being damaged. Moreover, since the surface 6a of the covering member 6 is flat, sunlight can be reliably refracted and guided to the lens 2.

  In the above embodiment, a trapezoidal prism is used as the refraction element 4, but the same effect can be obtained even with a spherical lens or a cylindrical lens. In the above embodiment, the covering member 6 is provided on the lens array 3. However, since the effect of the lens 2 can be obtained without the covering member 6, the optical element 1 is equivalent. An effect is obtained. However, the incident angle range of the parallel light beam 12 in this case becomes narrow.

  Next, the manufacturing method of the optical element 1 will be described with reference to FIGS. 4A to 4I.

  First, a method of forming the lens array 3 will be described with reference to FIGS. 4A to 4E. That is, the lens array 3 is formed by molding the lens array 3 on a resin substrate by a so-called 2P (Photo-Polymerization) method using an ultraviolet curable resin that is cured by ultraviolet irradiation. In this embodiment, a densely arranged rectangular lens array is used, but the lens shape is not limited thereto, and may be a hexagonal shape, a circular shape, or a cylindrical shape.

  More specifically, first, as shown in FIG. 4A, a rectangular concave stamper 31 for forming a lens array is manufactured. In this embodiment, a positive electron beam resist is applied on a quartz substrate serving as a stamper, a concave shape of the lens array is formed by electron beam exposure, and then the concave shape is transferred to the quartz substrate by dry etching. 31 was produced.

  Next, as shown in FIG. 4B, a high refractive index ultraviolet curable resin 33 is placed on the molding surface 32 of the rectangular concave quartz stamper 31 for molding the lens array. Further, as shown in FIG. 4C, one surface (surface) of the resin substrate 7 is pressed and pressed from above the ultraviolet curable resin 33 to mold the ultraviolet curable resin 33.

  Then, as shown in FIG. 4D, the resin substrate 7 is cured by being irradiated with ultraviolet rays from the other surface (back surface). Thereafter, the mold is released from the stamper 31, and the lens array 3 is formed on one surface of the substrate 7 as shown in FIG. 4E. In this way, a rectangular lens array 3 in which a plurality of lenses 2 are densely arranged is manufactured on one surface of the substrate 7.

  Next, a method for forming the refractive element 4 will be described with reference to FIGS. 4F to 4I. Here, the trapezoidal prism array which is the refractive element array 5 is formed using the light condensed by the lens array 3.

  First, as shown in FIG. 4F, a negative resist 34 for forming a trapezoidal prism array is applied by spin coating on the other surface of the substrate 7 which is the surface opposite to the surface on which the lens array 3 is formed. The negative resist 34 used in this embodiment is cured by absorbing ultraviolet rays and can be used as a permanent film.

  Next, as shown in FIG. 4G, light with a wavelength of around 365 nm having sensitivity of the negative resist 34 is incident as parallel light from the lens array 3 side.

  Here, the focal point of each lens 2 forming the lens array 3 is outside the negative resist 34. The negative resist 34 is exposed to light 30 having a spread, and the curing of the negative resist 34 is promoted to a shape corresponding to the intensity distribution. The negative resist 34 has a property that the curing range becomes wider as the exposure time is increased or the exposure intensity is increased. Therefore, in order to form the trapezoidal prism as the refraction element 4, the incident angle of the parallel light incident on the lens 2 is changed, the focal position is moved, the xz plane is formed, and the exposure is performed. By changing the intensity or exposure time, changing the exposure amount, and changing the curing depth, the y direction is formed, and the trapezoidal cured portion 35 is formed in the negative resist 34.

  Thereafter, the negative resist 34 is developed with 1% sodium carbonate to remove the uncured portion 36 other than the trapezoid cured portion 35 of the negative resist 34. As shown in FIG. A trapezoidal prism array (refractive element array 5) comprising elements 4) is obtained.

  Finally, as shown in FIG. 4I, a low refractive index resin 37 is applied on the lens array 3 by a spin coating method, or a flat mold is pressed and cured by ultraviolet irradiation to flatten the surface. Then, as shown in FIG. 2, the covering member 6 is formed.

  The refractive element 4 of the optical element 1 thus produced is arranged on the surface 10a side of the solar cell 10 as shown in FIG. 2 to manufacture a solar cell module. The refraction element 4 can be manufactured by a similar method when it is a spherical lens or a cylindrical lens.

In summary, the manufacturing method of the solar cell module of the present invention is as follows.
Attaching the lens 2 to one surface of the substrate 7;
Applying a photosensitive material to the other surface of the substrate 7;
The light from the light source is incident on the lens 2 as parallel light having a uniform light intensity distribution, and is condensed in the photosensitive material by the lens 2 to form the refractive element 4;
A step of disposing the refractive element 4 on the surface 10a side of the solar cell 10.

  As described above, according to the method for manufacturing a solar cell module of the present invention, since the refractive element 4 is produced using the lens 2, the optical axis 22 of the lens 2 and the optical axis 42 of the refractive element 4 are Can be matched. Further, since the refractive element array 5 is produced using the lens array 3, each of the lenses 2 constituting the lens array 3 and the refractive element array 5 corresponding to the lens 2 in a one-to-one relationship are formed. The center (optical axis) with each of the refraction elements 4 is completely coincident. For this reason, vignetting of the light beam between the lens 2 and the refraction element 4 does not occur, and all the parallel light flux 12 (sunlight) incident on the lens 2 can be incident on the refraction element 4. it can. Therefore, a solar cell module with high light collection efficiency can be realized.

It is a perspective view which shows one Embodiment of the solar cell module of this invention. It is a partial block diagram of a solar cell module. It is operation | movement explanatory drawing of a solar cell module. It is a 1st process drawing which shows the manufacturing method of the solar cell module of this invention. It is a 2nd process figure which shows the manufacturing method of the solar cell module of this invention. It is a 3rd process figure which shows the manufacturing method of the solar cell module of this invention. It is a 4th process figure which shows the manufacturing method of the solar cell module of this invention. It is a 5th process drawing which shows the manufacturing method of the solar cell module of this invention. It is a 6th process figure which shows the manufacturing method of the solar cell module of this invention. It is a 7th process drawing which shows the manufacturing method of the solar cell module of the present invention. It is an 8th process drawing which shows the manufacturing method of the solar cell module of this invention. It is a 9th process drawing which shows the manufacturing method of the solar cell module of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical element 2 Lens 20 Refractive surface 22 Optical axis 4 Refractive element 40 Refractive surface 42 Optical axis 6 Cover member 6a Surface 7 Substrate 10 Solar cell 10a Surface

Claims (7)

Solar cells,
An optical element disposed on the surface side of the solar cell and transmitting sunlight;
This optical element is
A lens disposed on the sunlight incident side and having a refracting surface facing the sunlight incident side;
A solar cell module comprising: a refractive element disposed on the solar cell side and having a refractive surface facing the solar cell side. The solar cell module according to claim 1, wherein
The solar cell module, wherein an optical axis of the lens and an optical axis of the refractive element are coincident. In the solar cell module according to claim 2,
The solar cell module, wherein the lens and the refractive element are arranged in a matrix. The solar cell module according to claim 1, wherein
The optical element further includes a covering member having a predetermined refractive index on the sunlight incident side of the lens. In the solar cell module according to claim 4,
The solar cell module according to claim 1, wherein the surface of the covering member on the sunlight incident side is flat. In the solar cell module according to claim 2,
The angle θ formed between the incident light entering the lens from the intersection of the optical axis of the lens and the refractive surface of the lens and the optical axis of the lens is
The length of the lens and the refractive element in the direction perpendicular to the optical axis of the lens in a plane formed by the incident light and the optical axis of the lens is L,
When the distance between the intersection between the optical axis of the lens and the refractive surface of the lens and the intersection between the optical axis of the refractive element and the surface of the refractive element on the solar cell side is H,
tanθ ≦ 0.5L / H
A solar cell module characterized by satisfying Attaching the lens to one side of the substrate;
Applying a photosensitive material to the other surface of the substrate;
A step of making light from a light source incident on the lens as parallel light having a uniform light intensity distribution, condensing the light on the photosensitive material by the lens, and forming a refractive element;
And a step of disposing the refractive element on the surface side of the solar cell.

Images