Patent Publication Number: US-2011056530-A1

Title: High concentrated photovoltaic (hcpv) solar cell module

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a high concentrated photovoltaic (HCPV) solar cell module, and in particular to a HCPV solar cell module utilizing Fresnel lens to concentrate sunlight. 
     2. The Prior Arts 
     Presently, in the energy regeneration resources, the high concentrated photovoltaic (HCPV) solar energy power generation system is the most promising one for its various advantages of material saving, low power cost, and high power generation efficiency, and it is generally considered as most suitable for used in a solar energy power plant, and is a mainstay and key-point in the development of the solar energy industry in the future. The high concentrated photovoltaic (HCPV) solar energy power generation system combining the high power Group III-V semiconductor solar cell and Fresnel Lens catches most of the attention for its capability of reducing the power generation cost significantly. 
     Refer to  FIG. 1  for a high concentrated photovoltaic (HCPV) solar cell module of the prior art. As shown in  FIG. 1 , the thin and light-weight Fresnel lens  10  replaces the conventional optical lens, such that in addition to reducing volume and weight significantly, it is capable of achieving fast production and low cost; a Group III-V semiconductor solar cell  20  of smaller area is disposed opposite to the Fresnel lens  10 , such that sunlight irradiated upon the Fresnel lens  10  are concentrated and focused onto the Group III-V semiconductor solar cell  20 , hereby generating electricity for outputting to the subsequent stages of electronic equipment as required, and also dissipating heat generated in this process through a heat dissipation base  30 . 
     However, the Fresnel lens utilized in a conventional high concentrated photovoltaic (HCPV) solar cell module is a structure made of a single layer of material, and its light concentration capability is rather insufficient, thus the high photoelectric conversion efficiency of the Group III-V semiconductor solar cell can not be fully utilized, therefore its power output is inadequate, and the cost benefit of the overall high concentrated photovoltaic (HCPV) solar cell module is not satisfactory. 
     SUMMARY OF THE INVENTION 
     In view of the problems and shortcomings of the prior art, a major objective of the present invention is to provide a high concentrated photovoltaic (HCPV) solar cell module, which utilizes a plurality of stacked-up Fresnel lenses in achieving focusing sunlight with a high concentration ratio, thus enhancing and raising the photoelectric conversion efficiency of the Group III-V semiconductor solar cell, in solving the problems and shortcomings of the prior art. 
     In order to achieve the above mentioned objective, the present invention provides a high concentrated photovoltaic (HCPV) solar cell module, comprising: a set of Fresnel lenses made of a plurality of thin, light-weight, and low-cost Fresnel lenses, a Group III-V semiconductor solar cell of high photoelectric conversion efficiency, and a substrate. In other words, instead of a single piece Fresnel lens utilized in the prior art, the present invention provides two or more Fresnel lenses, that are stacked on each other in an up-and-down manner and is disposed opposite and above the Group III-V semiconductor solar cell; and when it is irradiated by the sunlights, it will focus and concentrate the sunlights on the Group III-V semiconductor solar cell with high concentration ratio, in achieving high photoelectric conversion efficiency and large power output, thus reducing the number of the Group III-V semiconductor solar cells and high concentrated photovoltaic (HCPV) solar cell modules required, hereby lowering its production cost. In the process mentioned above, the temperature of the Group III-V semiconductor solar cells will be increased through the sunlights absorbed, and the heat thus generated will be dissipated into the ambient air through a substrate located at the bottom of the Group III-V semiconductor solar cell. Moreover, the present invention may also include a heat-electric conversion cell or a long wavelength solar cell, wherein, heat is converted into electricity, hereby further increasing its overall photoelectric conversion efficiency and the power generation efficiency. 
     Further scope of the applicability of the present invention will become apparent from the detailed descriptions given hereinafter. However, it should be understood that the detailed descriptions and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The related drawings in connection with the detailed descriptions of the present invention to be made later are described briefly as follows, in which: 
         FIG. 1  is schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module of the prior art; 
         FIG. 2  is schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module according to a first embodiment of the present invention; 
         FIG. 3  is a schematic diagram of a Fresnel lens utilized in a high concentrated photovoltaic (HCPV) solar cell module according to another embodiment of the present invention; 
         FIG. 4  is schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module according to a second embodiment of the present invention; 
         FIG. 5  is schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module according to a third embodiment of the present invention; and 
         FIG. 6  is schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module according to a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The purpose, construction, features, functions and advantages of the present invention can be appreciated and understood more thoroughly through the following detailed description with reference to the attached drawings. 
     Firstly, refer to  FIG. 2  for a schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module according to a first embodiment of the present invention. As shown in  FIG. 2 , a high concentrated photovoltaic (HCPV) solar cell module  100  comprises: a set of Fresnel lenses used to concentrate sunlights, and is composed of a first Fresnel lens  110  and a second Fresnel lens  120 ; a Group III-V semiconductor solar cell  130 , and a substrate  140 . 
     In the structure mentioned above, the set of Fresnel lenses are made of a plurality of Fresnel lenses, in the present embodiment, two Fresnel lenses are utilized as an example, but in actual application, it is not limited to this. Moreover, in the present invention, the set of Fresnel lenses are designed to produce varied power output depending on the angles formed by the Fresnel lenses. The first Fresnel lens  110  and the second Fresnel lens  120  are made of material of excellent optical property, such as the light transmission resin PMMA, PC, or PE, with its structure having saw-tooth mirrors on its lower side with gradually increasing angles outward, and with its texture made through utilizing light interference, diffraction, and receiving angle. In general, its focal length is designed as from 1 mm to 100 cm, with a light concentration ratio of 2×-1000×. In case that the first and second Fresnel lenses  110  and  120  are made of PMMA material, the flexibility of the Fresnel lenses can make them operate smoothly with the solar cells. Refer to  FIG. 3  for a schematic diagram of a Fresnel lens utilized in a high concentrated photovoltaic (HCPV) solar cell module according to another embodiment of the present invention (which is indicated with a first Fresnel lens  110 ), and that is provided with similar functions of light focusing. In the present invention, the first and second Fresnel lenses  110  and  120  are stacked up in an up-and-down manner, so as to raise the light concentration ratio significantly, and gather much more sunlights for focusing and concentrating them onto the Group III-V semiconductor solar cell  130 . By way of example, in case that the light concentration ratio of the first and second Fresnel lenses  110  and  120  are 15× respectively, then the light concentration ratio after stacking them up will become 15*15=225×. Naturally, in practice, more than two Fresnel lenses can be stacked up, for example, the light concentration ratio of three stacked-up Fresnel lenses each having light concentration ratio of 15×, can be 15*15*15=3375×. Therefore, the light concentration ratio of a plurality of stacked-up Fresnel lenses of the present invention can be in a range of about 3× to 3000×. 
     The Group III-V semiconductor solar cell  130  is disposed opposite to the first and second Fresnel lenses  110  and  120 , and absorbs the sunlights focused and concentrated by the first and second Fresnel lenses  110  and  120 , and converts them into electricity for output. Compared with the ordinary silicon crystal solar cell, the Group III-V semiconductor solar cell  130  is able to absorb energy of wider range of sunlight spectrum, thus its photoelectric conversion efficiency is increased significantly. In the present embodiment, the Group III-V semiconductor solar cell  130  is made of the materials selected from a group consisting of GaAs, GaP, InP, AlGaAs, GaInAs, AlGaP, GaInP, AlGaAsP, InGaAsP, AlGaInAsP, or their combinations. Alternatively, the Group III-V semiconductor solar cell  130  can be made of the materials selected from a group consisting of GaN, InN, GaAl, AlGaN, AlInN, AlInGaN, or their combinations. The substrate  140  is designed to have good heat dissipation capability, and is made of materials selected from a group consisting of: Ag, Cu, Al, Ni, Au, or their alloys. Therefore, the high temperature generated by the Group III-V semiconductor solar cell  130  through the sunlights concentrated by the first and second Fresnel lenses  110  and  120  can be dissipated into the ambient air through a substrate  140  disposed at the bottom of the solar cell  130 , so that it may operate in an appropriate temperature, hereby prolonging the service life of the Group III-V semiconductor solar cell  130 . 
     In passing through the second Fresnel lens  120  and the first Fresnel lens  100  sequentially, sunlights will be concentrated onto the Group III-V semiconductor solar cell  130  with a high concentration ratio, thus raising its photoelectric conversion efficiency significantly, achieving higher power output, while reducing the number required and area occupied by the Group III-V semiconductor solar cell  130 , in realizing the reduction of its production cost. 
     Refer to  FIG. 4  for a schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module  200  according to a second embodiment of the present invention. In this embodiment, a heat-electric conversion cell  250  is disposed between a Group III-V semiconductor solar cell  230  and a substrate  240 , thus generating electricity through a heat-electric effect. As such, the heat generated by the solar cell  230  is converted directly into electricity by the heat-electric conversion cell  250 , thus enabling the entire Group III-V semiconductor solar cell  230  to have good heat-electric conversion efficiency. 
     In addition, refer to  FIG. 5  for a schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module  300  according to a third embodiment of the present invention. In this embodiment, a long wavelength solar cell  360  is disposed between a Group III-V semiconductor solar cell  330  and a substrate  340 , for assisting in absorbing sunlights of long wavelength, in raising the photoelectric conversion efficiency of the solar cell module  300 . 
     Finally, refer to  FIG. 6  for a schematic diagram of a high concentrated photovoltaic (HCPV) solar cell module  400  according to a fourth embodiment of the present invention. In this embodiment, both a heat-electric conversion cell  450  and a long wavelength solar cell  460  are disposed between a Group III-V semiconductor solar cell  430  and a substrate  140 , hereby achieving even higher photoelectric conversion efficiency, and larger power output. 
     The above detailed description of the preferred embodiment is intended to describe more clearly the characteristics and spirit of the present invention. However, the preferred embodiments disclosed above are not intended to be any restrictions to the scope of the present invention. Conversely, its purpose is to include the various changes and equivalent arrangements which are within the scope of the appended claims.