Abstract:
The present invention relates to a concentrator-type photovoltaic receiver having homogenizer with fixing structure. The resent invention improves the structure of the homogenizer, which comprises a homogenizing part providing homogenizing function and a supporting part providing supporting and fixing function. The homogenizing part and the supporting part are formed integrally. The supporting part is a straight pillar. The user can bond the supporting part to the insulating substrate via glue and thus preventing the homogenizing part therein from collapse and contamination by dirt. Accordingly, good quality and lifetime can be maintained.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a homogenizer with fixing structure, and particularly to a homogenizer in a concentrator-type photovoltaic receiver. 
       BACKGROUND OF THE INVENTION 
       [0002]    Concentrator-type photovoltaic power generation acquires photo energy via a contractor-type photovoltaic receiver and enhances power generating efficiency by concentrating a great deal of photo energy. When solar energy is focused by the Fresnel lens, it will enter a transparent light-guiding pillar with a shape close to an upside-down pyramid, namely, a homogenizer. The bottom side of the homogenizer is a smooth surface with a main function of evening the energy of the light spot focused by the Fresnel lens. If the energy of the light spot is not evened by the homogenizer but illuminated directly on the solar cell, due to excess concentration of energy, the optoelectronic conversion efficiency is not well. In addition, because the incident angle of sunlight is not fixed but varies instantly with time, a tracker system is required for a concentrator-type solar-cell module. The tracker system will adjust to the optimum angle instantly according to the sunlight angle. The function of the homogenizer here is to improve the tolerance in angle of the tracker system as well as in dimensions during assembling. Thereby, it is an extremely important and functional device. 
         [0003]    Currently, the homogenizer is still assembled manually. Owing to its functional requirement, the homogenizer is an inverted-pyramid-shaped device with a wide top and a narrow bottom. With the top-heavy property, it&#39;s difficult to control the accuracy during bonding. In other words, the homogenizer is bonded on the solar cell by glue, which is a sticky fluid before drying off. Thereby, before hardening, the homogenizer located on the glue tends to tilt slightly by external force. Or it tilts during manual assembly and topples gradually before the glue is hardened. Even if the homogenizer is tilted but not toppled over, during subsequent practical operations, it is no guarantee that the tracker system will not collapse under rotation. 
         [0004]    In addition to the tilt and collapse problem, how to maintain surface cleanness of a homogenizer is another major problem. Because a homogenizer makes the incident light to reach uniformly and completely the concentrator-type solar cell at the bottom by means of internal total reflection, the cleanness of its side surface is the key point. If dirt or moisture exists on the surrounding surface of a homogenizer, total reflection will be destroyed, leading to light leakage and loss. 
         [0005]    Besides, the contact interface of a homogenizer and glue contact may be the critical place where light leakage occurs. During manual assembly of a homogenizer, if the homogenizer is pressed excessively on the glue to make the homogenizer deep into the glue, the glue will be squeezed and pushed to the bottom surface of sides of the homogenizer and hence resulting in glue spill. Glue spill will cause loss in light energy. Consequently, the light energy reaching the concentrator-type solar cell is reduced and thus lowering the efficiency. 
         [0006]    Refer to  FIG. 1A . According to the prior art, at most, an external frame  4  is adopted for assisting gluing of the homogenizer  3  to the concentrator-type solar cell  11  on the insulating substrate  13 . Nonetheless, the drawbacks described above will appear. The homogenizer  3  is still in an unstable status. It tends to tilt, move, or even collapse, and thus deteriorating the gluing quality substantially. In addition, the gluing height of the homogenizer  3  is not even, the final concentrator-type photovoltaic receiver will not have good receiving quality. 
         [0007]    Moreover, refer to  FIG. 1B . This is extracted from the US patent application US 2009/0223555. In the application, a hollow concentrating cup is disclosed. The concentrating cup is supported and fixed by means of the supporting stands on both sides. Although quality instability caused by gluing the homogenizer can be prevented, the optical efficiency of the concentrating cup cannot compete with the homogenizer. Besides, these supporting stands extending towards both sides occupy substantial space. If the concentrating cup is replaced by a homogenizer, the problem of light leakage and loss on side surfaces due to dirt accumulated after long-term usage will also occur. 
         [0008]    Accordingly, because the instability of a homogenizer during gluing may introduce defects for a concentrator-type photovoltaic receiver, the present invention provides a concentrator-type photovoltaic receiver having homogenizer with fixed structure for solving the problem. 
       SUMMARY 
       [0009]    An objective of the present invention is to provide a concentrator-type photovoltaic receiver having homogenizer with fixed structure. The integrally-formed homogenizer has the function of isolating dirt, and hence extending the lifetime and quality of the concentrator-type photovoltaic receiver. 
         [0010]    Another objective of the present invention is to provide a concentrator-type photovoltaic receiver having homogenizer with fixed structure. No extra frame to the homogenizer is required for assisting supporting the homogenizer. Thereby, the space occupied by a single photovoltaic receiver can be reduced. 
         [0011]    Still another objective of the present invention is to provide a concentrator-type photovoltaic receiver having homogenizer with fixed structure. The homogenizer has an integrally-formed supporting structure, so that the originally unstable homogenizer can be fixed on the concentrator-type solar cell with certainty. Thereby, the stability of the concentrator-type photovoltaic receiver can be enhanced. 
         [0012]    Still another objective of the present invention is to provide a concentrator-type photovoltaic receiver having homogenizer with fixed structure. The assembly is simple. In addition to more rapid assembly than the homogenizer according to the prior art, the assembly quality is also ensured. 
         [0013]    For achieving the objectives described above, the present invention discloses a concentrator-type solar cell, glue, and a homogenizer. The glue is disposed on the concentrator-type solar cell; and the homogenizer is disposed on the glue. The homogenizer comprises a supporting part and a homogenizing part. The supporting part is a transparent hollow pillar, and further connects with an insulating substrate under the concentrator-type solar cell. The homogenizing part is a solid transparent body with its top wider than the bottom and disposed on the concentrator-type solar cell and at the center of the supporting part. A top-wide region of the homogenizing part connects with a top of the supporting part. Under such a structure, it is convenient to glue the homogenizer. In addition, tilt or collapse will not occur after gluing; the cleanness of the homogenizer can be maintained as well. Thereby, the bonding efficiency, the performance, and the lifetime of the homogenizer can be enhanced simultaneously. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1A  shows a schematic diagram of the gluing result according to the prior art; 
           [0015]      FIG. 1B  shows a schematic diagram of the concentrating cup according to the prior art; 
           [0016]      FIG. 2  shows a structural schematic diagram of the homogenizer according to a preferred embodiment of the present invention; 
           [0017]      FIG. 3  shows a three-dimensional diagram of the overall structure according to a preferred embodiment of the present invention; 
           [0018]      FIG. 4A  shows a cross-sectional view before gluing according to a preferred embodiment of the present invention; 
           [0019]      FIG. 4B  shows a cross-sectional view after gluing according to a preferred embodiment of the present invention; 
           [0020]      FIG. 5A  shows a cross-sectional view before gluing according to another preferred embodiment of the present invention; 
           [0021]      FIG. 5B  shows a cross-sectional view during gluing according to another preferred embodiment of the present invention; 
           [0022]      FIG. 5C  shows a cross-sectional view after gluing according to another preferred embodiment of the present invention; 
           [0023]      FIG. 6A  shows a bottom view of the cylindrical homogenizer according to a preferred embodiment of the present invention; 
           [0024]      FIG. 6B  shows a bottom view of the square-pillar homogenizer according to a preferred embodiment of the present invention; and 
           [0025]      FIG. 6C  shows a bottom view of the polyhedron homogenizer according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    In order to make the structure and characteristics as well as the effectiveness of the present invention to be further understood and recognized, the detailed description of the present invention is provided as follows along with embodiments and accompanying figures. 
         [0027]    It is possible to produce defects during the bonding process of the homogenizer according to the prior art. Accordingly, for overcoming the technical defects, the present invention is provided for improving and solving the problems. 
         [0028]    First, refer to  FIG. 2 . This figure discloses the structure of the homogenizer . according to the present invention, which structure also characterizes the present invention. As shown in the figure, the homogenizer  3  comprises a supporting part  31  and a homogenizer  32 , which two are formed integrally. The supporting part  32  is a transparent hollow pillar, and particularly, a straight pillar. It provides the supporting function for the homogenizer  3 . The homogenizing part  32 , on the other hand, distributes the focused sunlight uniformly to the solar cell for the homogenizer  3 . 
         [0029]    The structure of the homogenizing part  32  is not limited to the inverted trapezoidal pillar; it could be a paraboloidal surface, similar to a bullet, or a semi-spherical body. Nonetheless, in general, the structure is a solid transparent body with its top wider than the bottom. Thereby, in order to be formed integrally with the supporting part  31 , the homogenizing part  32  is located at the center of the supporting part  31 . The top-wide region  321  is connected with the top  311  of the supporting part  31 . 
         [0030]      FIG. 3  discloses the schematic diagram of the relative locations of various devices during the application of the present invention. As shown in the figure, glue  2 , a concentrator-type solar cell  11 , a metal conducting layer  12 , and an insulating substrate  13  are disposed below the homogenizer  3 . The glue  2  is disposed on the concentrator-type solar cell  11 . The metal conducting layer  12  is disposed between the concentrator-type solar cell  11  and the insulating substrate  13 . The metal conducting layer  12  is a metal thin film used for electrical conduction. In practice, the thick of the metal conductive layer  12  is very thin. The thickness shown in the figure is only for expression purpose. 
         [0031]    For the details of the structure, the metal conductive layer  12  cab be further divided into a first metal conductive layer  121  and a second metal conductive layer  122 . The concentrator-type solar cell  11  is disposed on the first metal conductive layer  121 . The electrodes at the bottom of the concentrator-type solar cell  11  are connected directly with the first metal conductive layer  121 . In addition, the concentrator-type solar cell  11  is also connected electrically with the second metal conductive layer  122  via a plurality of metal wires  14  and hence forming a complete circuit. Moreover, the first and second metal conductive layers  121 ,  122  are connected with external circuitry and thus leading out electrical energy. 
         [0032]      FIGS. 4A and 4B  show cross-sectional views before and after gluing of the homogenizer  3  according to the present invention. During assembling the homogenizer  3  described above, because the homogenizing part  32  is located at the center of the supporting part  31  and the height thereof is smaller than the depth of the supporting part  31 , as the supporting part  31  contacts the insulating substrate  13 , the homogenizing part  32  of the homogenizer  3  will be located exactly above the concentrator-type solar cell  11  and contacts a portion of the glue  2 . Thereby, the homogenizing part  32  can be bonded above the concentrator-type solar cell  11  via the glue  2 . Meanwhile, the supporting part  31  will be fixed by the glue  2 . Except for the top region, the homogenizing part  32  will be sealed and isolated. Thereby, external dirt will not contaminate the homogenizing part  32 . 
         [0033]    In addition to the bonding method described above,  FIGS. 5A to 5C  show another bonding method. As shown in the figure, in addition to the glue  2 , external bonding glue  21 , which is insulating and whose transparency is not required, can be used for assisting bonding. Then, the glue  2  is only used for bonding the homogenizing part  32  and the concentrator-type solar cell  11 . On the other hand, the external bonding glue  21  is applied at the periphery of the bottom  312  of the supporting part  31  for further reinforcement. According to the present embodiment, normal insulating glue with lower cost is adopted for fixing the supporting part  31  on the insulating substrate  13 . Thereby, the cost can be lowered and the selection of glue is flexible. 
         [0034]    Without the assistance of the supporting part  31 , the homogenizing part  32 , which is top-heavy because of its top-wide and bottom-narrow structure, is difficult to be stabilized and fixed on the glue  2 . Besides, it is also hard to maintain its horizontal position. By forming integrally with the supporting part  31 , the bonding effect is enhanced by the help of the supporting part  31  and the homogenizing part  32  can stand stably on the concentrator-type solar cell  11 . 
         [0035]    The shape of the supporting part  31  can be designed freely as a cylindrical pillar, a square pillar, or a polyhedral pillar depending on the shape of the homogenizing part  32 , as long as the shape of the homogenizer  32  is a straight central pillar.  FIGS. 6A to 6C  show bottom views of the structure of the homogenizer  3 . As shown in the figure, the homogenizing part  32  is truly located at the center of the supporting part  31 . In addition, the thickness of the supporting part  31  is very thin. The critical point is on the flatness of the bottom for ensuring a horizontal position of the central homogenizing part  32  after assembly. 
         [0036]    In the homogenizer  3 , the heights of the supporting part  31  and the homogenizing part  32  are already fixed. Thereby, during assembling, the contact condition between the bottom of the homogenizing part  32  and the glue  2  can be stably controlled. Thereby, glue spill, caused by excessive reach of the homogenizing part  32  into the glue  2  and by pushes and squeezes of the glue  2  to the side surface of the homogenizing part  32 , can be avoided. Consequently, the situation of light leakage caused by glue spill can be prevented accordingly. 
         [0037]    Finally, in order to make the light pass through the homogenizer  3  and the glue  2  after being focused by Fresnel lens and reach the concentrator-type solar cell  11  smoothly, the material of the homogenizer  3  can be transparent high-polymer synthesized resin, glass, or quartz. The fabrication method is not limited. No matter die casting, grinding, molding, or ejection, once it&#39;s cost effective, the fabrication method can be adopted. Moreover, the glue  2  is insulating glue pervious to light. Thereby, conduction of the circuit of various conductive devices will not be affected by adherence of the glue  2 . 
         [0038]    The homogenizer in the concentrator-type photovoltaic receiver having homogenizer with fixing structure according to the present invention can have a better bonding result during assembling. The top-heavy homogenizer can be stable and not easy to collapse during the operation of a tracker system and thus extending the lifetime. In addition, the homogenizing part of the homogenizer can be protected from pollution of outdoor dirt. Moreover, because it is not required to fine-tune the locations of the homogenizer and the undried glue, manpower and time can be saved, leading to tremendous increase in assembling efficiency. Thereby, the present invention provides a concentrator-type photovoltaic receiver having substantial economic values. 
         [0039]    Accordingly, the present invention conforms to the legal requirements owing to its novelty, nonobviousness, and utility. However, the foregoing description is only embodiments of the present invention, not used to limit the scope and range of the present invention. Those equivalent changes or modifications made according to the shape, structure, feature, or spirit described in the claims of the present invention are included in the appended claims of the present invention.