JP2002289898A - Concentrating solar cell module and concentrating photovoltaic power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost concentrating solar cell module, in which sunlight is condensed on a photovoltaic element without irregularities in a quantity of light, without chromatic aberrations and with satisfactory efficiency, and to provide a concentrating photovoltaic power generation system which is constituted of the module and a tracking device. SOLUTION: The concentrating solar cell module is composed of a primary optical system 408 by which the sunlight radiated from the sun is condensed, a secondary optical system 108 by which the condensed sunlight is totally reflected on the incident face and by which the sunlight is totally reflected on the side face so as to be emitted from an emission face and the photovoltaic element 204, which is arranged immediately after the emission face of the system 108. The system 108 is composed of a transmissive, solid and uniform medium, and its side face 202 is smooth. The system 408 is an optical system, whose focus is situated near the incident face 109 of the system 204, and it holds the system 108 on the side face of the system 108 near the focus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concentrating solar cell module to be mounted on a solar tracking device and to be used in a simple and inexpensive manner. The present invention relates to a concentrating solar cell module that emits light, and a concentrating solar power generation system using the concentrating solar cell module.

[0002]

2. Description of the Related Art Conventionally, a photovoltaic power generation system using a solar cell module has been attracting attention as an energy source that is safe and does not burden the environment. In order to be competitive in terms of cost and economic efficiency, the focus has been on the development of more efficient and cheaper solar cell modules.

[0003] From such a viewpoint, a concentrating solar cell module and a concentrating solar power generation system composed of the concentrating solar cell module and a solar tracking device have been attracting attention in recent years. In a normal photovoltaic power generation system, the solar cell module itself is fixed at a fixed position, but it goes without saying that the relationship between the sun and the earth changes every moment. The relative angle becomes the optimum angle only for a moment, and it can be said that at other times, the solar energy is received at an inappropriate angle. This applies not only to the direction (so-called hour angle) of the sun as viewed from the solar cell module side, but also to the seasonal change (declination change) of the solar path. In addition, the reflectivity of the solar cell module surface also increases as the angle of incidence of the solar rays increases with distance from the normal of the solar cell module. I have. Such losses are said to be as much as 20-30% of the energy that should be received.

[0004] In order to solve such inappropriateness of the light receiving angle, it is only necessary that the solar cell module always keeps an optimum angle with respect to the sun, and a solar tracking type solar power generation system is devised from such a concept. It is expected that annual power generation will be improved by 25% to 40% by performing sun tracking.

[0005] Similarly, a solar tracking type concentrating solar power generation system has been studied for the purpose of reducing the unit cost of power generation. According to the concentrating photovoltaic power generation system, the most expensive photovoltaic elements among the components of the concentrating photovoltaic module that make up the photovoltaic power generation system can be greatly saved, resulting in extremely large cost reduction. Becomes

Further, as is generally said, since the generated voltage increases as the light intensity increases, the ratio of the output energy to the incident energy, that is, the conversion efficiency, is improved, and the photovoltaic elements are arranged in the same area. A large output will be obtained as compared with the case of laying.

In order to sufficiently obtain such effects, it is necessary to construct a concentrating photovoltaic power generation system that condenses light at a high magnification. In this case, an optical system for efficiently condensing sunlight is provided. Concentrating solar cell modules will be essential.

Conventionally, as a means for condensing sunlight, as shown in FIG. 10, a photovoltaic element 204 is provided parallel to the Fresnel lens 201 at a position substantially at the focal length of the Fresnel lens 201, and The solar light 107 incident on the photovoltaic element 204 is condensed and incident on the photovoltaic element 204.

However, according to this method, the sunlight 107 cannot be converged at one point as the aperture of the Fresnel lens 201 is increased due to the spherical aberration and chromatic aberration of the Fresnel lens 201. There was a restriction that the caliber of the can not be enlarged.
In addition, due to the spherical aberration and chromatic aberration of the Fresnel lens 201, the condensed sunlight 107 cannot be uniformly radiated to the photovoltaic element 204, causing a decrease in the efficiency of the photovoltaic element 204 and, in some cases, a rise in temperature only in a local area, As a result, the photovoltaic element 204 was damaged. Also, the photovoltaic element 20
4 has a multi-junction structure (p made of several different materials)
When an n-junction is arranged so as to overlap in the light traveling direction), the wavelength distribution on the photovoltaic element 204 varies due to chromatic aberration, and the conversion efficiency of the photovoltaic element 204 is greatly reduced.

Further, the shape of the area 302 where the square or circular Fresnel lens 201 is irradiated with sunlight is almost circular near the focal point, and when a square photovoltaic element 204 is used, as shown in FIG. The area 302 irradiated with the sun rays and the photovoltaic element 204 did not completely overlap, and the sun rays 107 could not be used effectively.

In order to solve such a problem, a means is adopted in which sunlight rays condensed by a primary optical system such as a Fresnel lens are led to the photovoltaic element again by a secondary optical system arranged in front of the photovoltaic element. Is now available. As the secondary optical system, an internal mirror, an optical fiber, a frustoconical lens, or the like is used.

An example utilizing an internal mirror is disclosed in
Japanese Patent Publication No. 307803 discloses a conventional example of a tapered internal mirror having a large-diameter end with a light-receiving surface as a secondary optical system.
In this structure, when the solar light is incident on the secondary optical system at a shallow angle, a part of the solar light incident on the inner mirror may go out to the incident side, resulting in poor efficiency.
Generally, the reflectivity of aluminum or silver used as a reflector of the inner mirror is 85 to 95% (visible region), and when sunlight is reflected several times by the inner mirror and guided to the photovoltaic element,
There is also a problem that the energy of the solar ray is reduced every time it is reflected on the internal mirror, and the solar ray cannot be efficiently guided to the photovoltaic element. In addition, it is necessary to consider the deterioration of the reflection material.

An example using an optical fiber is disclosed in Japanese Unexamined Patent Publication No.
No. 335004 and Japanese Unexamined Patent Publication No. 9-54215 have been proposed, but all of them have a high manufacturing cost, are difficult to increase in size, and, due to the structure of the optical fiber, the allowable angle of incidence of sunlight on the incident surface is narrow. As a result, in order to eliminate the uneven light amount and the chromatic aberration, it is necessary to take a sufficient focal length of the primary optical system and the length of the optical fiber, and there is a problem that the size of the concentrating solar cell module becomes large. further,
In addition, there is also a problem that the tracking device for tracking it needs to be large.

As an example using a frusto-conical lens, Japanese Patent Laid-Open Publication No. Hei 3-171614 discloses a secondary optical system in which a frusto-conical lens having a large diameter end face as a light receiving end face is provided on the surface of a photovoltaic element. A mounted example is described. With this structure, when sunlight rays enter the secondary optical system shallowly,
In some cases, a part of the incident solar rays exited to the incident side, and the efficiency was low. In addition, since the secondary optical system is supported only by bonding the photovoltaic element to the photovoltaic element with a transmissive member, a stress such as a peeling force is applied to the transmissive member and the photovoltaic element for a long time, and in terms of reliability, There was a problem.

[0015] Further, none of the above-mentioned methods has provided an inexpensive structure for efficiently concentrating sunlight on a photovoltaic element without unevenness in light amount and chromatic aberration.

[0016]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an inexpensive concentrating solar cell module for efficiently condensing sunlight onto a photovoltaic element without unevenness in light amount and chromatic aberration, and the concentrating solar cell module. An object of the present invention is to provide a concentrating solar power generation system including a solar cell module and a tracking device.

[0017]

SUMMARY OF THE INVENTION The present invention has been made based on the above recognition.

That is, the concentrating solar cell module of the present invention comprises: a primary optical system for condensing sunlight rays radiated from the sun, a substantially total incidence of the condensed sunlight rays on the incident surface, and a total reflection on the side faces. In a concentrating solar cell module comprising a secondary optical system that emits light at the exit surface and a photovoltaic element disposed immediately after the exit surface of the secondary optical system, the secondary optical system has It is made of a real and uniform medium, the side surface has smoothness, and the primary optical system is an optical system that focuses substantially near the entrance surface of the secondary optical system. It is characterized by holding a secondary optical system.

According to this configuration, of the sunlight rays incident from the incident surface of the secondary optical system, those that reach the side surface are totally reflected on the side surface having smoothness with high efficiency, and the length of the secondary optical system is reduced. Is greater than or equal to a certain value, the sunlight rays in the secondary optical system are mixed, and the sunlight rays can be efficiently guided to the photovoltaic element without unevenness in the light amount and chromatic aberration.

Further, since the secondary optical system is held on the side surface of the secondary optical system near the focal point, the secondary optical system is strengthened only at this point without obstructing the total reflection of the sunlight in the secondary optical system. Can be held. In other words, if the secondary optical system is held at the position where the sunlight rays are reflected on the side surface of the secondary optical system, energy loss occurs because total reflection does not occur in this part, but the secondary optical system near the focal point There is an area on the side where sunlight does not enter, and by holding the secondary optical system in this area, the secondary optical system is strengthened only at this point without obstructing total reflection of the sunlight in the secondary optical system Can be held.

Here, the state in which the unevenness of the light amount and the chromatic aberration are eliminated means that the sunlight in the wavelength region contributing to the power generation of the photovoltaic element is caused by the unevenness of the light amount and the chromatic aberration which do not affect the power generation performance of the photovoltaic element. Say the state that became.

The term “substantially full incidence” as used in this specification means that it is difficult to concentrate 100% of the sunlight on the incident surface of the secondary optical system due to the aberration of the primary optical system or the like. Considering the reflection loss and the like at the time, it refers to a state in which sunlight is incident with an efficiency of about 90%.

The term "uniform medium" as used herein means a medium whose refractive index is uniform regardless of the location or the propagation direction.

In the concentrating solar cell module of the present invention, the shape of the exit surface of the secondary optical system is preferably substantially the same as that of the photovoltaic element. According to such a configuration, sunlight rays emitted from the exit surface of the secondary optical system can be efficiently guided to the photovoltaic element.

Further, it is preferable that the shape of the rear part of the secondary optical system from the incident surface is columnar or tapered from the exit surface to the entrance surface. According to such a configuration, it is possible to prevent energy loss such as returning to the direction of the incident surface again while the solar light incident from the incident surface of the secondary optical system repeats total reflection.

Further, it is preferable that a transmissive member having transparency is provided between the secondary optical system and the photovoltaic element, and the refractive index of the transmissive member is larger than the refractive index of the secondary optical system. With this configuration, it is possible to suppress the reflection loss when the solar ray that has traveled in the secondary optical system exits from the exit surface of the secondary optical system, and to efficiently guide the solar ray to the photovoltaic element.

Further, it is preferable that the exit surface of the secondary optical system and the photovoltaic element are in close contact with each other. According to such a configuration,
When the photovoltaic element has a surface layer on the surface, its refractive index is 2-3, whereas the refractive index of glass or resin used as a secondary optical system is 1.4-1.9. Due to the low value, the solar rays that have advanced through the secondary optical system can be more efficiently guided to the photovoltaic element.

It is preferable that a reflection film is provided on the side of the secondary optical system where the secondary optical system is held. According to this configuration, the concentrator photovoltaic module of the present invention causes the solar rays condensed by the primary optical system to enter from the center of the incident surface of the secondary optical system due to an assembly error or a tracking error. Even when the sunlight reaches the portion holding the secondary optical system, the sunlight is reflected by the reflection film, and the loss at this portion can be minimized.

It is preferable that a protective layer be provided so as to cover the side surface of the secondary optical system and not to contact the side surface of the secondary optical system. According to such a configuration, it is possible to prevent troubles such as dust and dirt adhering to the side surface of the secondary optical system and reducing the reflectance on the side surface during long-term use, and to maintain the performance of the secondary optical system for a long time. Can be.

Further, a concentrating solar power generation system according to the present invention is characterized in that the concentrating solar cell module according to the present invention is combined with a solar tracking device.

According to the concentrating photovoltaic power generation system of the present invention, a tracking type photovoltaic module equipped with an inexpensive concentrating photovoltaic module that efficiently condenses sunlight onto a photovoltaic element without unevenness in light amount and chromatic aberration It becomes a concentrating solar power generation system.

[0032]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photovoltaic element, a primary optical system for condensing sunlight radiated from the sun, and a secondary optical system for guiding the condensed sunlight to the photovoltaic element. And a concentrating solar power generation system including the concentrating solar cell module and a tracking device. Hereinafter, each component of the present invention will be described in detail.

(Concentrating Solar Cell Module) A concentrating solar cell module is a primary optical system which is located on the outermost surface on the light receiving side and which firstly receives sunlight from the sun, and which is condensed by the primary optical system. A secondary optical system that guides light rays to a photovoltaic element using refraction and total reflection, a photovoltaic element disposed immediately after the secondary optical system, a primary optical system, a secondary optical system, and a photovoltaic element. It consists of a housing that is intended to be held or protected from the outside environment. Further, in addition to the concentrating solar cell module composed of one of each of the above components, a plurality of photovoltaic elements and a plurality of secondary optical systems are provided in one housing and one primary optical system (a plurality of primary optical systems). The primary optical system is formed by integral molding.) There is also a unit-type concentrating solar cell module constituted by: In addition, if the photovoltaic element has a specification in consideration of the influence from the external environment such as a waterproofing treatment and an insulation treatment, a separate casing for protecting the photovoltaic element from the external environment is not required. Further, if the secondary optical system and the photovoltaic element are configured to be held in a part of the primary optical system, a separate housing for holding them is not required.

In the concentrating solar cell module, the photovoltaic element, which converts sunlight energy into electric energy, has a copper circuit board for connecting the photovoltaic element and extracting electric energy. It is common to use together with a circuit board, a lead wire for extracting electric energy from the circuit board to the outside of the concentrating solar cell module, and a heat sink attached to the back surface of the circuit board to suppress a rise in temperature of the photovoltaic element. In the case of the unit-type concentrating solar cell module, a plurality of photovoltaic elements are connected in series or parallel as appropriate in the module, and electrical energy is extracted out of the concentrating solar cell module with a lead wire. Is also good.

[0035] Regardless of the above-described configuration, any configuration that achieves the same function can be included.

(Concentrating Solar Power Generation System) A concentrating solar power generation system is a system that generates power by combining the above concentrating solar cell module and a tracking device. Specifically, one or a plurality of the concentrating solar cell modules are mechanically connected to a tracking device for use. In this case, if necessary, a holding member for holding the concentrating solar cell module, a support mechanism for rotatably supporting, and a transmission mechanism for transmitting the driving force of the tracking device are necessary, if necessary. And introduce it appropriately. In addition, the tracking device generally includes a control unit that predicts the sun path and controls the tracking device in accordance with the path, a sensor for detecting the position of the sun in fine weather, and the like. In addition, the DC power generated by the concentrating solar cell module is used as it is, stored once in a storage battery and used as needed, or used after DC power is converted to AC power by a power converter. .

[0037] Regardless of the above-described configuration, any configuration that achieves the same function can be included.

(Primary optical system) The primary optical system is only required to be capable of condensing sunlight rays radiated from the sun and guiding it to the incident surface of the secondary optical system.
A biconvex lens, a prism, a lens that collects light using refraction, such as a compound lens, or a reflecting mirror that collects light using reflection, such as a concave mirror, or a combination of these can be considered. However, the present invention is not limited to the above, and may include all elements that realize the same function. The primary optical system is located on the outermost surface of the concentrating solar cell module, and is generally called a condensing lens, a lens, a primary optical element, a primary lens, a reflecting mirror, and the like, in addition to the primary optical system.

In designing the primary optical system, it is necessary that sunlight rays in a wavelength region contributing to power generation of the photovoltaic element enter the incident surface of the secondary optical system.

As the shape of the opening of the primary optical system, there are various shapes such as a rectangle, a circle, a polygon such as a regular hexagon, etc., but in a concentrating solar cell module in which the power generation per unit area is emphasized. , A shape such as a rectangle or a polygon that can be arranged without gaps is preferable.

Further, by forming the primary optical system with an aspherical surface or using an aromatic lens (a lens in which two lenses having different optical characteristics are bonded together), spherical aberration is substantially eliminated, and the solar rays are collected at one point. Can light. When a Fresnel lens is used for the primary optical system, the same effect can be obtained by forming the uneven surface with a surface approximated by a curved surface or an aspheric surface. In addition, chromatic aberration can be substantially eliminated by using an achromatic lens, an abnormal partial dispersion lens, a diffractive optical element, or the like in the primary optical system. However, since the chromatic aberration can be eliminated by the mixing effect of the secondary optical system, the primary optical system only needs to guide the sunlight in the wavelength range that contributes to the power generation of the photovoltaic element to the incident surface of the secondary optical system. .

The material constituting the primary optical system may be a transparent organic material such as glass, rubber or resin, a transparent crystal, a combination thereof, or an air lens or a liquid lens utilizing air or liquid. Conceivable.

Further, as the material, a material having excellent weather resistance due to being exposed to the external environment is preferable, and a material which is hardly deteriorated by ultraviolet rays and by rain, temperature and humidity is particularly preferable.

It is preferable that the transmittance in a wavelength region contributing to the power generation of the photovoltaic element is high, and the transmittance is 90%.
It is more preferable that there is the above. In addition, by using a material having selectivity in the transmission wavelength, or by adding an additive having the same function to the material, it is possible to cut sunlight in a short wavelength region that causes deterioration of the material. Further, by providing various coating layers on the front surface and the back surface of the primary optical system, functions such as reduction of reflectance, cutting of ultraviolet rays, and friction resistance of the primary optical system can be added. In addition, by using a high refractive index material, sunlight can be collected with a shorter focal length, and as a result, the size of the concentrating solar cell module can be reduced.

(Secondary optical system) A secondary optical system is a system in which sunlight rays condensed by a primary optical system are substantially totally incident on an incident surface, totally reflected on a side surface and emitted from an exit surface, and immediately after the secondary optical system. It is only necessary that the photovoltaic element arranged in the above can guide sunlight without uneven light amount and chromatic aberration. The shape may be a prism, a cylinder, a truncated pyramid, a truncated cone, or a polygonal prism, a polygonal truncated prism, or a shape with different entrance and exit surfaces, but is not limited to those listed above and has similar functions. Are realized, and these are generally called a secondary optical system, a secondary optical element, a secondary lens, a light guide, or the like.

Also, regardless of the shape of the incident surface, by setting the shape of the exit surface to be the same as the shape of the photovoltaic element, the sunlight can be efficiently guided to the photovoltaic element.

Further, the shape of the rear part of the entrance surface of the secondary optical system is tapered from the exit surface such as a columnar or truncated pyramid to the entrance surface, so that the incident surface of the secondary optical system has Even when a light ray enters at a shallow angle, a part of the incident sunlight rays can be guided to the photovoltaic element without being reflected inside the secondary optical system and going out to the incident surface side.

The advantage of the secondary optical system is that, for example, when a prism made of glass is used, sunlight rays incident on the incident surface of the secondary optical system at any angle are almost completely incident on the incident surface, and are exposed on the side surface. The light can travel straight through the total reflection or secondary optical system and be guided to the exit surface. However, since energy loss of sunlight is caused by reflection on the incident surface and the exit surface, it is preferable to provide an antireflection film or the like to reduce the energy loss due to the above-mentioned reflection.

Normally, by increasing the overall length of the secondary optical system, unevenness in light amount and chromatic aberration are eliminated (see FIG. 3).
reference. Details will be described later. In determining the overall length of the secondary optical system, the total length of the secondary optical system should be such that it does not affect the power generation performance of the photovoltaic element and has uneven light intensity and chromatic aberration in consideration of the refractive index and various characteristics of the material of the secondary optical system. It is preferable that the photovoltaic element can be used with high efficiency.

The material constituting the secondary optical system is a transparent organic material such as glass, rubber or resin, a transparent crystal, or a combination thereof, or an air lens or liquid lens using air or liquid. Is also conceivable. Further, the material preferably has a high transmittance in a wavelength region that contributes to power generation of the photovoltaic element, and the transmittance is 90%.
It is more preferable that there is the above. That is, in the wavelength region where the transmittance is low among the wavelength regions contributing to the power generation of the photovoltaic element, the energy loss is increased by increasing the length of the secondary optical system. In addition, by using a material having selectivity in the transmission wavelength or by mixing an additive having the same function into the material, a short wavelength region that causes material deterioration can be cut. In addition, by using a high refractive index material, sunlight can be mixed with a shorter secondary optical system length, and as a result, the size of the concentrating solar cell module can be reduced.

Also, since sunlight rays condensed by the primary optical system enter the secondary optical system, a rise in the temperature of the secondary optical system can be considered. Therefore, it is preferable to use a material having excellent heat resistance. Glass having excellent heat resistance and low material cost includes glass. As the glass, white plate glass generally used as a surface material of a solar cell module and various optical glasses can be used.

The reflectivity of the side of the secondary optical system at which sunlight is totally reflected is theoretically 100%, but the surface smoothness and the surface roughness of the side surface are greatly reduced due to the attachment of dust and dirt. Is preferably small, and more preferably a treatment such as mirror polishing. In addition, under long-term use, dust and dirt adhere to the side surface of the secondary optical system, so that the above-described reflectance is greatly reduced. By providing a protective layer or the like, the performance of the secondary optical system can be maintained for a long time.

Further, conventionally, since the secondary optical system was merely bonded to the photovoltaic element with an adhesive, a creep force was applied to the transmissive member and the photovoltaic element for a long period of time, and there was a problem in reliability. Was. However, by designing the solar beam passing through the primary optical system to focus substantially near the entrance surface of the secondary optical system, there is an area on the side of the secondary optical system near the focal point where total reflection of sunlight does not occur. By holding the secondary optical system in the area, the secondary optical system can be firmly held only at this location without obstructing total reflection of sunlight in the secondary optical system.

However, even under such a design, the sunlight condensed by the primary optical system is deviated from the optical axis and guided to the entrance surface of the secondary optical system due to an assembly error or a tracking error. Since it is conceivable that sunlight may reach a portion holding the secondary optical system, it is preferable that a portion holding the secondary optical system be provided with a reflective film such as silver vapor deposition or aluminum vapor deposition beforehand.

(Photovoltaic element) A photovoltaic element is an element that converts solar energy into electric energy, and is a member configured to generate an electric output by receiving solar rays alone or in combination. As the photoelectric conversion element, a photoelectric conversion element such as silicon, gallium arsenide, cadmium tellurium, copper indium selenide, or the like can be used, but is not limited to the above, and includes all that realize the same function. sell. In general, in addition to photovoltaic elements, they are called solar cells, solar cells, cells, photoelectric conversion elements, photovoltaic element cells, and the like.

Further, the photovoltaic element is arranged immediately after the secondary optical system. Specifically, means for disposing a transmissive member having transmissivity between the secondary optical system and the photovoltaic element, and using a transmissive member having a refractive index larger than that of the secondary optical system Also, by means of bringing the exit surface of the secondary optical system into close contact with the photovoltaic element, it is possible to efficiently guide the sunlight that has traveled in the secondary optical system to the photovoltaic element. As means for bringing the exit surface of the secondary optical system into close contact with the photovoltaic element, there are means for pressing the exit surface and the photovoltaic element, and means for forming the photovoltaic element on the exit surface. Further, by using an elastic material for the transmissive member, it is possible to prevent the secondary optical system and the photovoltaic element from interfering with each other and from damaging the surface of the photovoltaic element.

[0057]

EXAMPLES Examples of the present invention will be described below.
The substantial content of the present invention is not limited to the specific description of the following embodiments.

(Embodiment 1) FIGS. 1 to 7 show a first embodiment of the present invention.
The following shows an example. This figure schematically shows a portion related to the concentrating solar power generation system and the concentrating solar cell module.

In FIG. 1, reference numeral 101 denotes a concentrating solar power generation system, and a plurality of concentrating solar cell modules 10
2 and a tracking device 103.

The tracking device 103 is capable of capturing the sun position and tracking the sun using a control device having a calendar and a clock function and a sun position detection sensor 104.

As a tracking method, a method of tracking by rotating an elevation angle and an azimuth around an independent rotation axis, such as a telescope of an observatory or a high-fidelity gun, or a seasonal change of the sun path (declination). After setting an elevation angle corresponding to (change in), there is a method in which tracking is performed only at the hour angle, and the like.

The accuracy of the tracking device 103 is required to be higher as the light collecting magnification of the light collecting solar cell module 102 is higher.

Further, a plurality of concentrating solar cell modules 1
The DC power generated in step 02 is connected outside of the concentrating solar cell module via the lead wire 207 after being connected in series or parallel as appropriate, and used as it is or stored once in the storage battery and used as needed. Is used after being converted into AC power by the power converter.

The concentrating solar cell module 102 was fixed to the holding member 106 of the tracking device 103 with bolts and nuts. As fixing means, screws and snap fit,
Other joining means such as a permeable member, a double-sided tape, a fixing band, welding, caulking and the like can be used, but a detachable joining means is preferable in consideration of maintainability.

The concentrating solar cell module 102 includes a Fresnel lens 201 (primary optical system) for condensing the sunlight 107 and guiding it to the incident surface 109 of the secondary optical system 108, The light beam 107 is substantially totally incident on the incident surface 109, is totally reflected on the side surface 202, and is emitted from the exit surface 2.
The photovoltaic element 204 emitted from the light-emitting element 03 and disposed immediately after the secondary optical system 108 has no unevenness in the amount of light and no chromatic aberration.
07, and the sun rays 10 disposed immediately after the secondary optical system 108 and guided from the secondary optical system 108.
7, a photovoltaic element 204 for converting DC power into DC power,
A circuit board 205 that distributes the DC power generated by the photovoltaic element 204 to a positive pole and a negative pole and holds the photovoltaic element 204, and guides the DC power distributed by the circuit board 205 to a lead wire 207. An electrode tab 206 and a connector 30 for outputting DC power generated by the concentrating solar cell module 102 to the outside of the concentrating solar cell module
3, a cooling structure for radiating heat generated by the photovoltaic element 204 to the outside air via the circuit board 205 to the heat conductive sheet 208 to the heat sink 209, and light from the outside environment holding the above components. It comprises a housing 301 for protecting the electromotive force element 204.

The Fresnel lens 201 is made by injection molding using an acrylic resin, and is designed to be substantially focused on the vicinity of the incident surface 109 of the secondary optical system 108. Further, among the optical lenses, the Fresnel lens 201 has advantages that it can easily remove spherical aberration, has a short focal length, has a large aperture, is lightweight, and can be mass-produced at low cost. Further, an ultraviolet absorber was added to the Fresnel lens 201 to prevent material deterioration due to ultraviolet rays. In addition, antireflection films are provided on the front and back surfaces of the Fresnel lens 201 to reduce energy loss when the sun rays 107 enter or exit the Fresnel lens 201.

The secondary optical system 108 is formed by cutting and polishing a white plate glass material having a low iron content and a high transmittance in a wavelength region contributing to the power generation of the photovoltaic element, so that the exit surface of the secondary optical system 108 can be formed. Was formed in the shape of a quadrangular prism having substantially the same shape as the photovoltaic element.

In addition to the methods described above, the secondary optical system 108 using glass may be prepared by cutting a selected glass into an appropriate size, heating the glass again, pressing the glass again, and then polishing the glass. Pressing the melted glass in a molten state at a high temperature to form it into a lens shape and then polishing it, and a polishing-free creation method that can be created by simply pressing the melted low-melting glass material at a low temperature .

Further, an anti-reflection film is provided because there is a concern about loss due to reflection at the entrance surface and the exit surface of the secondary optical system 108.

The secondary optical system 108 and the photovoltaic element 204 are transmitted between the secondary optical system 108 and the photovoltaic element 204 in order to prevent the surface of the photovoltaic element 204 from being damaged by interference between the secondary optical system 108 and the photovoltaic element 204. Member 3 having heat resistance and heat resistance
04 was a silicone rubber. Transmissive member 304
As the material, other than silicone rubber, fluorine rubber, acrylic rubber, urethane resin, EVA and the like can be used, but it is necessary to appropriately select them in consideration of ultraviolet resistance and heat resistance, refractive index, and transmittance. Also, generally these materials
Since the refractive index of the glass used as the secondary optical system is low, and reflection at the exit surface of the secondary optical system is concerned, measures or mitigation measures such as providing an antireflection film on the exit surface of the secondary optical system have been taken. is necessary.

For the photovoltaic element 204, a crystalline silicon semiconductor was used. This photovoltaic element 204 is developed for a concentrating solar cell module, and is provided on the non-light receiving surface side for outputting a current collecting electrode and DC power collected from the current collecting electrode to the outside of the photovoltaic element. It has an electrode 305 (positive electrode / negative electrode), and the entire area on the light receiving surface side is a power generation unit.

As the circuit board 205, a copper circuit board 306 (positive electrode / negative electrode) was directly bonded to a ceramic substrate having high thermal conductivity and being an insulator. As the ceramic substrate, an alumina plate, an AlN substrate or the like can be used.

As the heat conductive sheet 208, a heat conductive rubber sheet, silicone compound, silicone grease, or the like, which is generally used for heat dissipation when a semiconductor and a heat sink are joined, can be used.

As the heat sink 209, an extruded aluminum material was cut into appropriate dimensions and used. The surface was subjected to black alumite treatment for the purpose of improving cooling performance and weather resistance.

The housing 301 was formed by joining an aluminum alloy plate by pressing, bending, and welding. The surface was subjected to alumite treatment for the purpose of improving weather resistance. As a material of the housing 301,
In addition to the processed aluminum alloy plate, a processed metal or non-metal plate, a molded housing made of a resin having weather resistance, and the like can be used.

The procedure for producing the concentrating solar cell module 102 using the above-described components will be described below.

First, the photovoltaic element 204 and the electrode tab 2
06 by reflowing the copper circuit board 30 on the circuit board 205
6 was soldered.

Next, the circuit board 205 is connected to the heat conductive sheet 2.
08 to the heat sink 209 with screws.

Next, the heat sink 209 is mounted on the housing 301.
Was fixed by screwing. At this time, the electrode tab 20 is provided through a hole for taking out the electrode tab 206 provided on the housing 301.
6 was taken out, and the hole was subjected to a water stopping treatment. Then, a lead wire 207 with a connector 303 was connected to the electrode tab 206.

Next, the secondary optical system 10 is positioned so that the incident surface of the secondary optical system is located near the focal point of the Fresnel lens 201.
The secondary optical system holding portion 307 provided on the side surface 202 of No. 8 was held by a part of the housing 301. At this time, the emission surface 203 of the secondary optical system 108 was in contact with the photovoltaic element 204 via the transparent member 304.

Finally, the Fresnel lens 201 was fixed to the opening of the housing 301 via the rubber bushing 308.

Hereinafter, the concentrating solar cell module 1 will be described.
The procedure for creating the concentrator photovoltaic power generation system 101 by using No. 02 will be described.

The concentrating solar cell module holding portions 401 of the plurality of concentrating solar cell modules 102 prepared above were fixed to the holding member 106 on the tracking device 103 with bolts and nuts. And a plurality of concentrating solar cell modules 1
02, connected in series or in parallel as appropriate, and output to the outside through the external output line 105, and can be used as it is, stored once in a storage battery and used as needed, It was used after being converted into AC power.

The concentrating solar cell module 102 produced as described above has a Fresnel lens 201 as a primary optical system.
The sunlight 107 into the incident surface 10 of the secondary optical system 108
9, the sunlight rays 107 incident on the incident surface 109 of the secondary optical system 108 and reaching the side surface 202 are totally reflected at the side surface 202 with high efficiency. The sun rays 107 are mixed and the sun rays 10
7 was able to be efficiently guided to the photovoltaic element 204 without unevenness of the light amount and chromatic aberration (see FIG. 3. FIG. 3 shows that the sunlight 107 traveling in the secondary optical system 108 has a distance from the entrance surface 109. The longer the length, the less uneven the light intensity is.)

Further, there is an area on the side surface 202 of the secondary optical system 108 near the focal point where the total reflection of the sunlight 107 does not occur. The area, that is, the secondary optical system holding unit 307 holds the secondary optical system 108. Thereby, the secondary optical system 108 can be firmly held only at this location without obstructing the total reflection of the sun rays 107 in the secondary optical system 108 (FIG. 4).
And FIG. FIG. 4 shows that by setting the focal point of the Fresnel lens, which is the primary optical system, near the incident surface 109 of the secondary optical system 108, total reflection of the sunlight 107 occurs on the side surface 202 of the secondary optical system 108 near the focal point. No secondary optical system holding unit 307 is shown. Further, the focal point of the primary optical system is shifted from the incident surface 109 of the secondary optical system 108 to the photovoltaic element 20.
Although the secondary optical system holding unit 307 can be secured each time it approaches the 4th side, the length of the sunlight 107 in the secondary optical system 108 until the unevenness in the light amount and the chromatic aberration is eliminated becomes longer. The focal point is the entrance surface 10 of the secondary optical system 108
9 indicates that the vicinity is preferable. ).

As shown in FIG. 6, in this embodiment, the reflection film 309 is provided in the secondary optical system holding portion 307 of the secondary optical system 108 by aluminum evaporation, silver evaporation, or the like. Due to assembling errors and tracking errors of the photovoltaic solar cell module, sunlight condensed by the primary optical system is incident on the secondary optical system at a position shifted from the center of the incident surface, and the sunlight is incident on the secondary optical system holding unit. Even when it reaches, the sunlight is reflected by the reflective film 309, and the energy loss in this portion can be minimized.

The shape of the secondary optical system 108 on the rear side from the incident surface 109 may be a column (see this embodiment and FIG. 7) or a shape that tapers from the exit surface to the incident surface (see FIG. 7). By doing so, it was possible to prevent a loss such that sunlight rays incident from the incident surface of the secondary optical system returned to the incident surface again.

Also, the secondary optical system 10
8, the side surface 202 of the secondary optical system 108 is covered in a state where the side surface 202 is not in contact with the side surface. Thus, the performance of the secondary optical system could be maintained for a long time.

(Embodiment 2) FIG. 8 shows a second embodiment of the present invention.

In contrast to the concentrating solar cell module of Embodiment 1, in this embodiment, a plurality of photovoltaic elements 204 and a plurality of secondary optical systems 108 are composed of one housing 301 and one Fresnel lens 201 ( (A plurality of Fresnel lenses are formed by integral molding.). As a result, the number of parts is reduced and the number of assembling steps is reduced, so that the cost can be reduced.

Although the present embodiment is an example in which two photovoltaic elements 204 are arranged, the present invention is not limited to this, and the cost can be further reduced by disposing the photovoltaic elements in the depth direction.

In this embodiment, the protective cover 4 made of resin is separately provided as a stain-proofing measure against the side surface 202 of the secondary optical system 108.
03 was provided. In addition, a cooling structure is provided in which heat generated by the photovoltaic element 204 due to light collection is radiated to the outside air via the circuit board 205, the heat conductive sheet 208, the heat pipe 404, the heat sink 209, and the housing 301. Improved the cooling performance. In addition, heat sink 2
09 is formed by extrusion molding in the depth direction, so that one heat sink 2 is provided for a plurality of photovoltaic elements 204, for example, when a photovoltaic element is also arranged in the depth direction.
09, the heat sink processing cost and the number of assembling steps are reduced, and the cost can be reduced.

Further, by disposing the heat sink 209 in the concave portion provided in the housing 301, the concentrating solar cell module 102 can be made thinner, and the wind pressure resistance and strength of the tracking device can be reduced.

(Embodiment 3) FIG. 9 shows a third embodiment of the present invention.

In the present embodiment, a funnel-shaped reflecting mirror 407 is provided on the front surface of the secondary optical system 108 in contrast to the concentrating solar cell module of the first embodiment. Accordingly, even when the condensing solar cell module 102 shifts from the center of the incident surface 109 of the secondary optical system 108 due to a tracking error or the like, the sunlight 107 condensed by the Fresnel lens 201 as the primary optical system
The sunlight 107 captured by the reflecting mirror 407 is the secondary optical system 10
By being guided to the light incident surface 109 of FIG. 8, it becomes possible to catch more sunlight rays 107. In addition, these reflecting mirrors 407 can be easily formed by pressing an aluminum alloy plate having a high reflectance, and cost can be reduced.

[0096]

The concentrating solar cell module of the present invention has the following features.
A primary optical system that collects the sun's rays radiated from the sun,
A secondary optical system that emits the collected sunlight almost completely on the incident surface and totally reflected on the side surface and exits from the exit surface, and a photovoltaic element arranged immediately after the exit surface of the secondary optical system In the solar cell module, the secondary optical system is made of a solid and uniform medium having transparency, and the side surfaces have smoothness.
The primary optical system is an optical system that focuses substantially on the vicinity of the entrance surface of the secondary optical system, and by holding the secondary optical system on the side surface of the secondary optical system near the focal point, from the entrance surface of the secondary optical system Of the incident solar rays, those that reach the side face are totally reflected at the side face with smoothness with high efficiency, and by making the length of the secondary optical system a certain value or more, the sunlight rays in the secondary optical system Were mixed, and the solar light could be efficiently guided to the photovoltaic element without unevenness in the light amount and chromatic aberration.

Further, since the secondary optical system is held on the side surface of the secondary optical system near the focal point, the secondary optical system is strengthened only at this point without obstructing the total reflection of the sunlight in the secondary optical system. Could be held. In other words, if the secondary optical system is held at the position where the sunlight rays are reflected on the side surface of the secondary optical system, energy loss occurs because total reflection does not occur in this part, but the secondary optical system near the focal point There is an area on the side where sunlight does not enter, and by holding the secondary optical system in this area, the secondary optical system is strengthened only at this point without obstructing total reflection of the sunlight in the secondary optical system Can be held.

Also, by making the shape of the exit surface of the secondary optical system substantially the same as that of the photovoltaic element, the sunlight emitted from the exit surface of the secondary optical system can be efficiently guided to the photovoltaic element. Was completed.

Further, the shape of the rear part of the secondary optical system from the incident surface is made to be a column or a shape tapered from the exit surface to the incident surface, so that the solar light incident from the incident surface of the secondary optical system can be obtained. While repeating total reflection, it was possible to prevent energy loss such as returning to the incident surface direction again.

In addition, a transmissive member having a transmissivity is arranged between the secondary optical system and the photovoltaic element, and the refractive index of the transmissive member is set to be larger than that of the secondary optical system. As a result, it was possible to suppress the reflection loss at the time when the solar ray that has traveled in the secondary optical system exits from the exit surface of the secondary optical system, and to efficiently guide the solar ray to the photovoltaic element.

In addition, since the exit surface of the secondary optical system and the photovoltaic element are in close contact with each other, when the photovoltaic element has a surface layer on its surface, its refractive index is 2-3. The refractive index of glass, resin or the like used as a secondary optical system is 1.4.
Since it was as low as １1.9, the solar rays that had advanced through the secondary optical system could be more efficiently guided to the photovoltaic element.

Also, by providing a reflective film on the side of the secondary optical system where the secondary optical system is held, the concentrator photovoltaic module of the present invention can be used in the primary optical system due to assembly errors and tracking errors. Even when the condensed sunlight enters the secondary optical system at a position shifted from the center of the incident surface, and the sunlight reaches the portion holding the secondary optical system, the sunlight is reflected by the reflective film. , The loss in this part could be minimized.

In addition, by providing the protective layer in such a manner as to cover the side surface of the secondary optical system and not to contact the side surface of the secondary optical system, dust or dirt may be formed on the side surface of the secondary optical system during long-term use. It was possible to prevent trouble such as adhesion of dirt and a decrease in the reflectance on the side surface, and to maintain the performance of the secondary optical system for a long time.

Also, by combining the above concentrating solar cell module with a solar tracking device, an inexpensive concentrating solar cell module that efficiently condenses sunlight onto a photovoltaic element without unevenness in light quantity and chromatic aberration. A tracking-type concentrating photovoltaic power generation system equipped with the system was realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a solar power generation system illustrating a first embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating a first embodiment of the present invention.

FIG. 3 is a conceptual diagram illustrating a light amount distribution in a secondary optical system according to the first embodiment of the present invention.

FIG. 4 is a conceptual diagram illustrating a positional relationship between a focal point of a primary optical system and a secondary optical system.

FIG. 5 is a conceptual diagram illustrating a positional relationship between a focal point of a primary optical system and a secondary optical system.

FIG. 6 is a conceptual diagram illustrating a positional relationship between a focal point of a primary optical system and a secondary optical system.

FIG. 7 is a conceptual diagram illustrating the first embodiment of the present invention.

FIG. 8 is a configuration diagram of a concentrating solar cell module illustrating a second embodiment of the present invention.

FIG. 9 is a configuration diagram of a concentrating solar cell module illustrating a third embodiment of the present invention.

FIG. 10 is a configuration diagram illustrating a conventional example.

[Explanation of symbols]

 Reference Signs List 101 concentrating solar power generation system 102 concentrating solar cell module 103 tracking device 104 sun position detection sensor 105 external output line 106 holding member 107 sun ray 108 secondary optical system 109 entrance surface of secondary optical system 201 Fresnel lens 202 Side surface of secondary optical system 203 Exit surface of secondary optical system 204 Photovoltaic element 205 Circuit board 206 Electrode tab 207 Lead wire 208 Thermal conductive sheet 209 Heat sink 301 Housing 302 Area irradiated with sunlight 303 Connector 304 Transparency Member 305 Electrode 306 Copper circuit board 307 Secondary optical system holding unit 308 Rubber bushing 309 Reflective film 401 Concentrating solar cell module holding unit 403 Protective cover 404 Heat pipe 405 Concave portion 407 Reflecting mirror 408 Primary optical system

Claims (8)

[Claims] A primary optical system for condensing sunlight rays radiated from the sun, a secondary optical system for substantially condensing the condensed sunlight rays on an incident surface, totally reflecting on a side surface, and exiting on an exit surface; In a concentrating solar cell module consisting of a photovoltaic element arranged immediately after the exit surface of the secondary optical system, the secondary optical system is made of a transparent and uniform medium, and the side surfaces have smoothness. The primary optical system is an optical system that substantially focuses near the entrance surface of the secondary optical system, and holds the secondary optical system on the side surface of the secondary optical system near the focal point. Concentrating solar cell module. 2. The concentrating solar cell module according to claim 1, wherein the shape of the exit surface of the secondary optical system is substantially the same as that of the photovoltaic element. 3. The shape of a part behind the entrance surface of the secondary optical system,
The concentrating solar cell module according to claim 1, wherein the concentrating solar cell module is formed in a column shape or tapered from an emission surface to an incidence surface. 4. A transparent member having transparency between the secondary optical system and the photovoltaic element, wherein the refractive index of the transparent member is larger than the refractive index of the secondary optical system. Claim 1
4. The concentrating solar cell module according to any one of items 1 to 3. 5. The concentrating solar cell module according to claim 1, wherein the exit surface of the secondary optical system and the photovoltaic element are in close contact with each other. 6. The concentrating solar cell module according to claim 1, wherein a reflection film is provided on a side of the secondary optical system where the secondary optical system is held. 7. The device according to claim 1, further comprising a protective layer covering the side surface of the secondary optical system and not in contact with the side surface of the secondary optical system. Concentrating solar cell module. 8. A concentrating photovoltaic power generation system, comprising a combination of the concentrating solar cell module according to claim 1 and a solar tracking device.