Patent Publication Number: US-2013240024-A1

Title: Tree-shaped solar cell module

Description:
TECHNICAL FIELD  
     The present invention relates tree-shaped solar cell modules formed by combining solar cells in the form of trees for easy installation and solar power generation at various places. 
     The tree-shaped solar cell modules can be installed in the yards or gardens of houses or the rooftops of buildings to provide green zones and electricity necessary for the houses or buildings. 
     The tree-shaped solar cell modules can regularly be arranged along the center regions, boundary regions, or ridges of rice paddies, fields, or orchards for solar power generation, and since the tree-shaped solar cell modules can function as wind blocks, crops can be protected from typhoons and the like. For example, falling of crops or fruits may be prevented when a typhoon blows. 
     The tree-shaped solar cell modules can be installed like trees at regular intervals in a large farm for generating electricity without affecting farming. 
     The tree-shaped solar cell modules can be installed along a railroad to supply electricity necessary for trains. 
     The tree-shaped solar cell modules can be installed along a road or street as street trees, utility poles, streetlamps, antennas, and traffic lights. 
     The tree-shaped solar cell modules can be installed along or around waterways, reservoirs, lakes, or dams for converting sunlight into electricity. 
     The tree-shaped solar cell modules can be installed between trees on a mountain without having to remove trees from the mountain. In addition, the tree-shaped solar cell modules can easily be installed on a mountain slope which is too steep to plant crops so that such a steep mountain slope can be valuably used. 
     The tree-shaped solar cell modules can be installed like trees in a desert for solar power generation. In this case, since the tree-shaped solar cell modules function as wind blocks, sand may be less blown by wind, and plants such as grasses and trees may easily grow around the tree-shaped solar cell modules, thereby preventing desertification and developing green land. 
     Large tree-shaped solar cell modules can be installed in a desert. In this case, solar cells can be distant from the surface of the desert for reducing the influence of geothermal heat. This compensates for the disadvantage that the efficiency of silicon crystalline solar cells reduce as temperature increases. 
     In the related art, there are panel type solar cell modules and concentrated solar cell modules. Solar cells are arranged on a panel and are wired up, and the panel is covered and fixed to form a large solar cell module. Such solar cell modules may be arranged on the rooftops of small buildings, large areas developed from mountains, foreshores, or deserts for solar power generation. 
     Panel type solar cell modules of the related art have several disadvantages. First, although solar power is a kind of new regeneration energy, green areas are destroyed when mountains are developed for installing panel type solar cell modules, and the marine ecosystem may be damaged if panel type solar cell modules are arranged on a foreshore or sea. As a result, solar power cannot be green energy because green areas are destroyed to install panel type solar cell modules. 
     If such panel type solar cell modules of the related art are installed in a desert, the power generation efficiency of the solar cell modules reduces due to the high temperature of the desert. 
     After installation, such panel type solar cell modules are sloped and oriented in the same direction. Therefore, the solar cell modules can not be efficiently operated according to the movement of the sun. If the solar cell modules are configured to move according to the movement of the sun, the manufacturing costs increase, and energy loss increases. In addition, parts such as motors and bearings may be worn down and become out of order according to the time of use. 
     BACKGROUND ART 
     The present patent application claims priority of the following patent applications: Original Application, Priority Application 1, and Priority Application 2. 
     ORIGINAL APPLICATION Title of Invention: Tree-shaped solar cell module, Korean Patent Application No.: 10-2010-0122380, and Filing Date: Dec. 3, 2010. 
     PRIORITY APPLICATION Title of Invention: Tree-shaped solar cell module, Korean Patent Application No.: 10-2010-0125294, and Filing Date: Dec. 9, 2010. 
     PRIORITY APPLICATION Title of Invention: Tree-shaped solar cell module, Korean Patent Application No.: 10-2011-0056552, and Filing Date: Jun. 11, 2011. 
     Patent applications searched at Korean Intellectual Property Rights Information Service (KIPRIS) are listed below. 
     [Literature 1] Title of Invention: Leaf solar-cell equipped tree type electric power generation system, Korean Patent Application Publication No.: 10-2010-0047999, Publication Date: May 11, 2010. 
     [Literature 2] Title of Invention: Tree-type solar power generator, Korean Patent Application Publication No.: 10-2011-0030392, Publication Date: Mar. 23, 2011. 
     [Literature 3] Japanese Patent Application Laid-Open Publication No.: 2004-281788 (Oct. 7, 2004). 
     The three applications are listed as reference. 
     SUMMARY OF INVENTION 
     Technical Problem 
     The present invention provides solar cell modules in the form of a branch module, a trunk module, and a tree-shaped solar cell module in which the branch module and the trunk module are combined. 
     The tree-shaped solar cell module can also be used as a utility pole and a streetlamp, and the tree-shaped solar cell module does not include a structure that can be easily swung by wind. 
     Solution to Problem 
     A triangular branch module includes: a triangular frame formed of a material such as metals, concrete, wood, ceramic materials, and plastics and having a length of about 2 m to about 3 m; and solar cells are attached to the three sides of the triangular frame. 
     A trunk module includes an octagonal frame having a length of about 6 m to about 10 m and solar cells attached to the eight sides of the octagonal frame. 
     A fixing plate that can be fixed to the trunk module is provided on an end of the triangular branch module. 
     Nut holes are regularly formed in a lateral outer side of the trunk module so that the triangular branch module can be fixed to the trunk module. 
     The triangular branch module or the trunk module may include a polygonal or circular frame such as a triangular frame, a quadrangular frame, a pentagonal frame, a hexagonal frame, a heptagonal frame, and an octagonal frame. 
     In the triangular branch module or the trunk module, an assembly space region is formed in each side of the polygonal or circular frame such as a triangular frame, a quadrangular frame, a pentagonal frame, a hexagonal frame, a heptagonal frame, and an octagonal frame so that solar cells can be easily attached thereto. 
     In the triangular branch module or the trunk module, an internal cavity is formed in the polygonal or circular frame such as a triangular frame, a quadrangular frame, a pentagonal frame, a hexagonal frame, a heptagonal frame, and an octagonal frame. 
     A wire accommodation groove is formed in the assembly space region so that wires can be arranged therein. 
     Penetration holes are regularly formed in the wire accommodation groove to connect the wire accommodation groove and the internal cavity. 
     When a solar cell is attached to the assembly space region, wires of the solar cells are arranged in the wire accommodation groove and introduced into the internal cavity. 
     After solar cells are attached to the assembly space region of the trunk module, the triangular branch module is fixed to the nut holes formed in the lateral outer side of the trunk module, so as to form a tree-shaped solar cell module. 
     A utility pole crossarm and a transformer may be attached to an upper portion of the tree-shaped solar cell module so that the tree-shaped solar cell module can also be used as a utility pole. 
     An LED module may be attached to one side of the triangular branch module to use the triangular branch module as a streetlamp. 
     Leaf-shaped solar cells are not included in the triangular branch module of the tree-shaped solar cell module so that the tree-shaped solar cell module may not easily swung by wind. 
     Advantageous Effects of Invention 
     The tree-shaped solar cell module can be installed like a tree on sunny flatland or a steep slope of a mountain without reclamation or leveling. 
     When installing the tree-shaped solar cell module on a mountain, it is unnecessary to remove trees around the tree-shaped solar cell module as long as the trees interfere with the tree-shaped solar cell module. That is, forests can be conserved. 
     Since grasses can grow on the field or flatland around the tree-shaped solar cell module, the field or flatland where tree-shaped solar cell modules are installed can be used for farming. That is, the tree-shaped solar cell modules can be harmonized with the surrounding environments as new regeneration energy sources. 
     When the tree-shaped solar cell modules are installed in a desert, since solar cells are distant from the ground, solar power regeneration is less affected by geothermal heat, and thus efficiency reduction cased by high temperature can be prevented. 
     The tree-shaped solar cell modules of the present invention can be installed in a region of China suffering desertification for weakening wind, reducing transfer of sand, and forming environments suitable for growing plants. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1   a,    1   b,  and  1   c  are a perspective view of a triangular branch module  100 , a cross-sectional view of a triangular frame  10 , and a cross-sectional view for explaining assembly procedures of solar cells  18 . 
         FIGS. 2   d ,  2   e ,  2   f , and  2   g  are a perspective view of a quadrangular branch module  110 , a perspective view of a rhombus branch module  120 , a cross-sectional view of a quadrangular frame  10   a,  and a cross-sectional view for explaining assembly procedures of simple solar cell modules  22 . 
         FIGS. 3   h  and  3   k  are a cross-sectional view of a hexagonal frame  10   b  and a cross-sectional view for explaining assembly procedures of simple solar cell modules  22 . 
         FIGS. 4   m ,  4   n , and  4   p  are a perspective view of a circular branch module  130 , a cross-sectional view of a circular frame  10   d,  and a perspective view for explaining assembly procedures of simple solar cell modules  22   d.    
         FIGS. 5   q  and  5   r  are a plan view and a perspective view for explaining assembly procedures of a triangular pillar  40 , module auxiliary frames  50 , and simple solar cell modules  22 . 
         FIGS. 6   s  and  6   t  are a plan view and a perspective view for explaining assembly procedures of a triangular pillar  40 , angled end parts  55   b,  and simple solar cell modules  22 . 
         FIGS. 7   u  and  7   v  are a plan view and a perspective view for explaining assembly procedures of an octagonal pillar  40   c,  module auxiliary frames  50 , and simple solar cell modules  22 . 
         FIGS. 8   w  and  8   x  are a plan view and a perspective view for explaining assembly procedures of a circular pillar  40   d,  module auxiliary parts  50   b,  and simple solar cell modules  22 . 
         FIGS. 9   y  and  9   z  are a plan view and a perspective view for explaining assembly procedures of a circular pillar  40   d,  module auxiliary frames  50   b,  and simple solar cell modules  22   c.    
         FIGS. 10   a   1  and  10   b   1  are a plan view and a perspective view for explaining how a simple solar cell module  22  is attached to a branch module single frame  60 . 
         FIGS. 11   c   1  and  11   d   1  are a plan view and a perspective view for explaining how simple solar cell modules  22  are attached to a branch module dual frame  60   a.    
         FIGS. 12   e   1  and  12   f   1  are a plan view and a perspective view for explaining how simple solar cell modules  22  are attached to a branch module multiple frame  60   b.    
         FIGS. 13   g   1  and  13   h   1  are a plan view and a perspective view for explaining how a simple solar cell module  22   d  is attached to a branch module curve frame  60   d.    
         FIG. 14  is a transparent view showing how a trunk module  200  is fixed to a base  85  and how lines  89  extending from a line part  88  of the base  85  are laid in the ground. 
         FIG. 15  is a transparent view showing a lightening rod  1  attached to an end portion  83  of the trunk module  200  which is fixed to the base  85  as shown in  FIG. 14 . 
         FIG. 16  is an enlarged perspective view showing a portion of the trunk module  200 . 
         FIG. 17  is a view showing a tree-shaped solar cell module  400  in which rhombus branch modules  120  are attached to a trunk module  200 . 
         FIG. 18  is a partially enlarged view of  FIG. 17  showing the rhombus branch modules  120 . 
         FIG. 19  is a perspective view for explaining how branch coupling parts  90  are attached to the trunk module  200 . 
         FIG. 20  is a perspective view showing the trunk module  200  of  FIG. 19  after the branch coupling parts  90  are attached thereto. 
         FIG. 21  is a perspective view showing rhombus branch modules  120  attached to connection portions  92  of the branch coupling parts  90  shown in  FIG. 20 . 
         FIG. 22  is a view showing a tree-shaped solar cell module  500  assembled using branch coupling parts  90 . 
         FIG. 23  is a view showing one-piece supports  35  and fixing plates  36  for attaching branch modules to a trunk module  200 . 
         FIG. 24  is a perspective view showing a tree-shaped solar cell module  600  having electric pole crossarms  2  for being used as a utility pole, traffic lights, streetlights, or the like. 
         FIG. 25  is a view showing a tree-shaped solar cell module  650  in which flowerpots  77  having internal cavities are fixed to fixing portions  78  of a trunk module  200  at positions higher than a predetermined lower position so that tree roots can be put in the internal cavities to use the tree-shaped solar cell module  650  as street trees as well. 
         FIGS. 26   k   1  and  26   m   1  are a perspective view of a tree-shaped solar cell module  700  and a partially enlarged perspective view of a branch module  140 . 
         FIGS. 27   n   1  and  27   p   1  are a perspective view of a tree-shaped solar cell module  710  and a partially enlarged perspective view of a branch module  150 . 
         FIGS. 28   q   1  and  28   r   1  are a perspective view of a tree-shaped solar cell module  720  and a partially enlarged perspective view of a branch module  160 . 
         FIGS. 29   s   1  and  29   t   1  are a perspective view of a tree-shaped solar cell module  730  and a partially enlarged perspective view of a branch module  170 . 
         FIG. 30  is a plan view showing the tree-shaped solar cell module  730 . 
         FIG. 31  is a perspective view showing a tree-shaped solar cell module  730  to which more branch modules  170  are attached. 
         FIG. 32  is a plan view showing the tree-shaped solar cell module  730  of  FIG. 30 . 
         FIGS. 33   t ,  33   u , and  33   v  are views showing trunk modules  200  to which branch modules such as triangular branch modules  100 , quadrangular branch modules  110 , rhombus branch modules  120 , and circular branch modules  130  are respectively attached in an upward pattern ( FIG. 33   t ), a horizontal pattern ( FIG. 33   u ), and a downward pattern ( FIG. 33   v ). 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Configurations and embodiments of the present invention will now be described with reference to the accompanying drawings.  FIG. 1   a  is a perspective view showing a triangular branch module  100 . The triangular branch module  100  includes a pillar frame such as a triangular frame and solar cells attached to three sides of the triangular frame for generating electricity from sunlight. Such triangular branch modules  100  will be disposed around a trunk module  200  (described later) and fixed to the trunk module  200  like tree branches so as to form a tree-shaped solar cell module. 
     Referring to  FIGS. 1   a,    1   b,  and  1   c,  the triangular frame  10  of the triangular branch module  100  may be formed through processes such as extrusion, molding, assembling, and cutting. Materials that can be used for forming the triangular frame  10  include a metal such as aluminum and stainless steel, a ceramic material such as glass and concrete, resin such as plastic resin or vinyl resin, and combinations thereof. Even wood may be used for forming the triangular frame  10 . If the triangular frame  10  is formed of concrete, concrete including cement may be put in a mould together with reinforcing materials such as steel reinforcing bars, wires, and wire meshes. If the triangular frame  10  is formed of wood, the triangular frame  10  may be treated with a waterproof agent for waferproofing and insect proofing as well. 
     Assembly space regions  12  as large as possible are formed by recessing the three sides of the triangular frame  10  by 5 mm to 10 mm so as to attach solar cells thereto, and both sides of each corner  11  of the triangular frame  10  protrude as jaws  13  because of the relatively low assembly space regions  12 . The jaws  13  protrude away from the assembly space regions  12 . 
     An internal cavity  16  is formed in the triangular frame  10 . In the drawings, the internal cavity  16  has a triangular shape. However, the triangular frame  10  may have a circular or polygonal internal cavity  16  or may be solid without any internal cavity  16  according to manufacturing processes. In the present invention, the internal cavity  16  may be useful for arranging wires, and the shape and size of the internal cavity  16  may be determined according to a material used to form the triangular frame  10  so as to maintain the strength of the triangular frame  10 . 
     At least one wire accommodation groove  14  having a depth toward the internal cavity  16  is formed on each of the assembly space regions  12  so that electric wires can be arranged in the wire accommodation grooves  14  when solar cells are attached to the assembly space regions  12 . 
     Penetration holes (not shown) connecting the wire accommodation grooves  14  and the internal cavity  16  are regularly arranged in the length direction of the triangular frame  10 , that is, in a direction from a module end  23  of the triangular branch module  100  to a fixing part  26  as shown in  FIG. 1   a,  so that when solar cells are attached to the assembly space regions  12 , wires of the solar cells can be arranged from the wire accommodation grooves  14  to the internal cavity  16  through the penetration holes. 
     A fixing plate  24  is provided on an end of the triangular frame  10  so that the triangular frame  10  can be fixed to the outside of the trunk module  200  (described later) like a branch. According to the angle between the fixing plate  24  and the fixing part  26  of the triangular frame  10 , the angle of the triangular frame  10  and the orientations of the three sides of the triangular frame  10  are determined with respect to the vertical position of the fixing plate  24 . 
     Since the fixing plate  24  is vertically held and fixed to the outside of the trunk module  200  like a branch, the triangular frame  10  can be positioned upwardly, horizontal, or downwardly according to the assembling angle and directions of the fixing plate  24  and the fixing part  26  of the triangular frame  10 . 
     Therefore, when the triangular branch module  100  is attached to the trunk module  200 , the position of the triangular branch module  100  can be adjusted upward, horizontal, or downward. That is, it is apparent that the angle of the triangular branch module  100  from the trunk module  200  can be adjusted within a range smaller than the plane angle (180 degrees) of the trunk module  200  that will be installed vertically like a tree trunk. 
     When the triangular branch module  100  provided by attaching solar cells to the triangular frame  10  is assembled to the trunk module  200 , the three sides of the triangular frame  10  can be positioned at 0, 120, and 240 degrees, or 60, 180, and 300 degrees. That is, the three sides of the triangular frame  10  can be positioned in predetermined orientations within the 360-degree range by adjusting the orientation of the fixing plate  24  so that simple solar cell modules  22  attached to the triangular frame  10  can be oriented to receive sunlight effectively. 
     The fixing plate  24  is a plate that can be fixed to the trunk module  200 , and for this, fixing holes  27  are formed through the corners of the fixing plate  24 . 
     A wire hole  25  formed through the center portion of the fixing plate  24  is connected to the internal cavity  16 . 
     Electric wires  20  of solar cells  18  of the simple solar cell modules  22  are arranged in the wire accommodation grooves  14  and the internal cavity  16  and come out through the wire hole  25  of the fixing plate  24 . The electric wires  20  coming out through the wire hole  25  will now be referred to as connection wires  30 , and a connection plug  31  is attached to the ends of the connection wires  30 . 
     In the drawings showing an embodiment of the present invention, the fixing plate  24  has a rectangular shape. However, the fixing plate  24  may be manufactured in a different shape such as a quadrangular, circular, or polygonal shape. 
     Although not shown in the drawings of the embodiment, the fixing plate  24  may have an arch-shaped portion so that the fixing plate  24  can be attached to a circular pillar having a corresponding diameter. 
     Although not shown in the drawings of the embodiment, male screws may protrude from an end of the triangular branch module  100  or female screws may be formed in the end of the triangular branch module  100  instead of the fixing plate  24 . In this case, corresponding female screws or male screws may be provided on the outside of the trunk module  200  for screw coupling with the triangular branch module  100 . 
       FIG. 1   c  is a cross-sectional view showing how parts such as sheets  17 , solar cells  18 , and transparent glass plates  19  are assembled to the assembly space regions  12  of the triangular frame  10 . First, a sheet  17  may be attached to an assembly space region  12  of the triangular frame  10 , and a solar cell  18  may be placed in the assembly space region  12 . Then, wires  20  may be arranged in the wire accommodation grooves  14  and the internal cavity  16 , and a transparent glass plate  19  may be placed on the solar cell  18  and fixed. These procedures may be repeated to form the triangular branch module  100  having a long shape. 
     The sheet  17 , the solar cell  18 , and the transparent glass plate  19  are fixed by applying an adhesive to the jaws  13  formed at the corners of the assembly space region  12 . The fixing process may include a waterproof treatment. 
     The sheet  17 , the solar cell  18 , and the transparent glass plate  19  are well-known parts in the related art, and thus detailed descriptions thereof will not be provided. 
     Although now shown in the drawings, screw holes may be formed in portions of the sheet  17 , the solar cell  18 , and the transparent glass plate  19 , and corresponding screw holes may be formed in the assembly space region  12  for assembly using screws. However, the use of an adhesive may be advantageous, and an adhesive known in the related art such as silicone may be used. 
     As described above, the sheet  17 , the solar cell  18 , and the transparent glass plate  19  may be sequentially assembled to the triangular frame  10 . However, for efficiency, speed, and precision of an assembly process, the sheet  17 , the solar cell  18 , and the transparent glass plate  19  may be previously assembled as a simple solar cell module  22 . 
     In the following descriptions, only simple solar cell modules  22  or simple solar cell modules  22   d  may be shown and described without describing individual parts thereof for simple and clear explanation. 
     That is, solar cells are previously assembled into simple solar cell modules  22 , and then the simple solar cell modules  22  are attached to the assembly space regions  12  of the triangular frame  10  so that the triangular branch module  100  can be made simply, precisely, and rapidly. 
       FIG. 1   b  is a cross-sectional view of the triangular frame  10 , and  FIG. 1   c  is a sectional view showing how the sheets  17 , the solar cells  18 , and the transparent glass plates  19 , or the simple solar cell modules  22  are attached to the triangular branch module  100 . 
     In the above description and following description, the triangular frame  10  is a frame in which solar cells  18  or simple solar cell modules  22  are not yet attached to the assembly space regions  12 , and the triangular branch module  100  is a module provided by attaching solar cells  18  or simple solar cell modules  22  to the assembly space regions  12  of the triangular frame  10 , fixing the fixing plate  24  to an end of the triangular frame  10 , and connecting the connection plug  31  to ends of the connection wires  30  coming out through the wire hole  25  of the fixing plate  24 . 
     In the triangular branch module  100  made as described above, the triangular frame  10  may be a length selected according to the size of a tree-shaped solar cell module. In addition, the length of the triangular frame  10  may be selected depending on the strength of a material of the triangular frame  10 . 
     It is apparent that the triangular frame  10  can be manufactured in predetermined length and thickness so that the triangular frame  10  can be installed in a structurally stable state capable of resisting strong wind and not too thin or thick as compared with the trunk module  200  to form a visually balanced tree-shaped solar cell module. 
     The size of the triangular frame  10  may be determined according to the sizes of solar cells. That is, the assembly space regions  12  of the triangular frame  10  may be sized according to the sizes of solar cells available in the market. 
     For example, if solar cells having a size of 156 mm×156 mm or simple solar cell modules  22  having a width of 156 mm are used, the width of the assembly space regions  12  may be about 160 mm. In this case, the length between the neighboring corner  11  and jaw  13  of the triangular frame  10  may be about 20 mm, and the width of the triangular frame  10  from one corner  11  to the other corner  11  may be about 200 mm (160 mm+20 mm+20 mm). In this way, the size of the triangular frame  10  constituting the triangular branch module  100  may be determined. 
     The length of the triangular frame  10  may be determined according to the number of solar cells. For example, ten solar cells having a size of 156 mm×156 mm are arranged in a row in each assembly space region  12  of the triangular frame  10  or are assembled into a simple solar cell module  22 , the length of the triangular frame  10  may be about 1600 mm (1560 mm+the thick of the fixing plate  24 ). 
     That is, a manufacture can determine the length of the module  100  according to the number of solar cells  18  to be assembled. 
     An LED module having the same size as that of a simple solar cell module  22  may be attached to one of the assembly space regions  12  instead of the simple solar cell module  22 . 
     In this case, the triangular branch module  100  may be attached to a tree-shaped solar cell module like a branch in a manner such that the assembly space region  12  to which the LED module is attached faces downward. Then, the tree-shaped solar cell module can be used like a streetlight by turning on the LED module at night. 
     Alternatively, a reflection module such as a glass mirror or a reflection film on which aluminum is deposited may be attached to one of the assembly space regions  12  instead of the LED module. 
     In this case, the module  100  may be attached to a tree-shaped solar cell module in a manner such that the assembly space region  12  on which the reflection module is attached faces downward. Then, light may be reflected from the reflection module to a simple solar cell module  22  attached to a lower triangular branch module  100  to increase the efficiency of solar power generation and reduce manufacturing costs. 
     Since the module end  23  of the triangular branch module  100  is a portion receiving much sunlight, a simple solar cell module  22  having a small size may be attached to the module end  23 . 
     It is apparent that an LED module can be attached to the module end  23  instead of a simple solar cell module  22  to make the triangular branch module  100  easily recognized at night by turning on and off the LED module. 
     The wires  20  of the solar cells  18  or the simple solar cell modules  22  are arranged in the wire accommodation grooves  14  of the triangular branch module  100  and put in the internal cavity  16  through the penetration holes connecting the internal cavity  16  of the wire accommodation grooves  14 . Then, ends of the wires  20  are pulled out through the wire hole  25  of the fixing plate  24  as connection wires  30 , and the connection plug  31  is attached to the connection wires  30 . 
     The connection plug  31  will be electrically connected to a connection socket  34  (described later) of the trunk module  200 . 
     The triangular branch module  100  is a solar cell module shaped like a tree branch having no leaf so as not to be swung by wind. The thickness and length of the triangular branch module  100  is determined according to the size of a tree-shaped solar cell module to be made. That is, a small or large tree-shaped solar cell module can be made. 
     If a large tree-shaped solar cell module is made, twig modules (not shown) having designs and shapes similar to those of the triangular branch module  100  may be attached to the lateral sides of the triangular branch module  100  like twigs of a tree branch. However, such twig modules may be disadvantageous in terms of increasing wind influence, producing shadows, and increasing manufacturing costs. Therefore, after considering such disadvantages, the use of such twig modules may be determined. 
     Light receiving parts of the simple solar cell modules  22 , that is, the outer sides of the transparent glass plates  19  may be finely uneven like lotus leaves or coated with a cleaning agent so that contaminants such as dust can be easily separated by self cleaning 
     Such a finely uneven surface structure like lotus leaves or a cleaning agent for self cleaning is a technique known in the related art, and thus a detailed description thereof will be omitted. 
       FIG. 2   d  is a perspective view showing a quadrangular branch module  110 . The quadrangular branch module  110  is made in the same method as the triangular branch module  100  except for a quadrangular frame  10  corresponding to the triangular frame  10 . 
     Referring to  FIGS. 2   d ,  2   e ,  2   f , and  2   g , like in the triangular frame  10 , assembly space regions  12  are formed by recessing the four sides of the quadrangular frame  10   a  to a depth of about 5 mm to 10 mm so as to attach solar cells thereto, and both sides of each corner  11  of the quadrangular frame  10   a  protrude as jaws  13  because of the relatively low assembly space regions  12 . The jaws  13  protrude away from the assembly space regions  12 . 
     Like the triangular frame  10 , the quadrangular frame  10   a  includes an internal cavity  16 , at least one wire accommodation groove  14  formed in each assembly space region  12  and having a depth toward the internal cavity  16 , and penetration holes (not shown) regularly arranged in the length direction of the quadrangular frame  10   a  to connect the wire accommodation grooves  14  to the internal cavity  16 . 
     A fixing plate  24  is provided on an end of the quadrangular frame  10   a  so that the triangular frame  10  can be fixed to the outside of a trunk module  200  (described later). According to the angle between the fixing plate  24  and a end fixing part  26  of the quadrangular frame  10   a,  the angle of the quadrangular frame  10   a  and the orientations of the four sides of the quadrangular frame  10   a  are determined. 
     That is, the quadrangular frame  10   a  can be positioned upward, horizontally, or downward from the position of the fixing part  26  according to the angle of the quadrangular frame  10   a  from the fixing plate  24  that will be vertically installed. 
     After the quadrangular branch module  110  including the quadrangular frame  10   a  is attached to the outside of the trunk module  200  (described later) like a tree branch, the quadrangular branch module  110  may be extend upward, horizontally, or downward from the trunk module  200  which is vertically installed like a tree trunk. 
     Referring to  FIG. 2   d , the fixing plate  24  having a quadrangular shape is fixed to the quadrangular frame  10   a  of the quadrangular branch module  110  with no twist angle with the quadrangular frame  10   a.  Therefore, when the quadrangular branch module  110  is attached to the trunk module  200 , two of four simple solar cell modules  22  attached to opposite sides of the four sides of the quadrangular branch module  110  are located at upper and lower positions, that is, 0-degree and 180-degree positions, and the other two of the simple solar cell modules  22  are symmetrically located at left and right positions, that is, 90-degree and 180-degree positions. 
       FIG. 2   e  shows a rhombus branch module  120  in which a quadrangular frame  10   a  is fixed to a fixing plate  24  having a quadrangular shape with a twist angle of 45 degrees. Although the rhombus branch module  120  is assembled in the same method as the triangular branch module  100  and the quadrangular branch module  110 , after the rhombus branch module  120  is attached to the trunk module  200 , simple solar cell modules  22  are located at 45-degree, 135-degree, 225-degree, and 315-degree positions because the loading chambers  110   a  and the fixing plate  24  are fixed to each other with a twist angle of 45 degrees. If necessary, the quadrangular branch module  110  can be fixed to the fixing plate  24  with any twist angle from 0 to 360 degrees. 
       FIGS. 2   f  and  2   g  show how sheets  17 , solar cells  18 , and transparent glass plates  19 , or simple solar cell modules  22  are attached to the assembly space regions  12  of the quadrangular frame  10   a  to form the quadrangular branch module  110  or the rhombus branch module  120 . The assembly process is the same as that for the triangular branch module  100 , and thus a detailed description thereof will be omitted. 
       FIG. 3   h  shows a hexagonal frame  10   b  having the same structure as that of the triangular frame  10  or the quadrangular frame  10   a  except that the hexagonal frame  10   b  has a polygonal shape having more sides. The hexagonal frame  10   b  includes assembly space regions  12  on the six sides thereof, an internal cavity  16  therein, at least one wire accommodation groove  14  in each assembly space region  12 , and penetration holes connecting the wire accommodation grooves  14  and the internal cavity  16 . 
     Referring to  FIG. 3   k , like in the triangular frame  10  and the quadrangular frame  10   a,  sheets  17 , solar cells  18 , and transparent glass plates  19 , or simple solar cell modules  22  are attached to the assembly space regions  12  of the hexagonal frame  10   b  to form a hexagonal branch module or hexagonal trunk module  200 . 
     That is, as described above, a polygonal frame such as triangular, quadrangular, pentagonal, and hexagonal frames includes an assembly space region  12  on each side thereof, an internal cavity  16 , at least one wire accommodation groove  14  in each assembly space region  12  for arranging wires, and penetration holes arranged regularly in the length direction thereof to connect the internal cavity  16  and the wire accommodation grooves  14 . The polygonal frame can be used as a branch module or trunk module after attaching simple solar cell modules  22  to the polygonal frame. 
     A triangular frame or a quadrangular frame may be suitable for a branch module, and a pentagonal frame or a hexagonal frame may be suitable for a trunk module. The reason for this is that when the same solar cells are used, the circumference of a polygonal frame is determined whether the polygonal frame is a triangular frame, a quadrangular frame, or a hexagonal frame. That is, a polygonal frame having a large circumference is suitable for a trunk module rather than a branch module. 
     When it is intended to make a large tree-shaped solar cell module, a polygonal frame having many sides such as a pentagonal frame and a hexagonal frame may be used to form a branch module, and when it is intended to make a relative small tree-shaped solar cell module, a polygonal frame such as a triangular and a quadrangular frame may be used to form a branch module. For example, if it is necessary to use a hexagonal branch module in a small tree-shaped solar cell module, small solar cells made of small wafers or solar cells made through an electrode printing process and a laser cutting process may be used. 
     Referring to  FIGS. 4   m ,  4   n , and  4   p , a long circular frame  10   d  includes: an internal cavity  16   d  ; jaws  13  protruding at regular intervals from the outer side thereof; assembly space regions  12   d  formed between the jaws  13  and lower than the jaws  13  by about 5 mm to 10 mm, the assembly space regions  12   d  having a curvature like the long circular frame  10   d ; wire accommodation grooves  14   d  formed in the assembly space regions  12   d  toward the internal cavity  16   d,  and a plurality of penetration holes regularly arranged in the length direction of the long circular frame  10   d  to connect the wire accommodation grooves  14   d  and the internal cavity  16   d.    
     According to the same method as described above, simple solar cell modules  22   d  are attached to the assembly space regions  12   d  of the circular frame  10   d,  and edges of the simple solar cell module  22   d  are fixed to the jaws  13  using any coupling method. The simple solar cell modules  22   d  have a curvature corresponding to that of the assembly space regions  12   d  for easy assembly. 
     The simple solar cell modules  22   d  are made of sheet solar cells and transparent glass plates having a curvature corresponding to that of the assembly space regions  12   d.    
     A fixing plate  24  is fixed to an end of the circular frame  10   d  having a predetermined length, and the simple solar cell modules  22   d  are attached to the outer side of the circular frame  10   d  to form a circular branch module  130 . The circular branch module  130  may be used as a branch module. Alternatively, the circular branch module  130  may be used as a trunk module  200  by installing the circular branch module  130  at an upright position using a fixing plate  81  (described later) instead of the fixing plate  24 . The trunk module  200  will be described later in detail. 
     As described above, assembly space regions and wire accommodation grooves are formed on the outer side of such a polygonal frame as a triangular, quadrangular, pentagonal, hexagonal, or circular frame. Sheets, solar cells, and transparent glass plates, or simple solar cell modules are attached to the assembly space regions, and a waterproof adhesive is applied between the edges of the simple solar cell modules and jaws of the polygonal frame. Wires of the simple solar cell modules are arranged in the wire accommodation grooves and the internal cavity and are pulled out through a wire hole of a fixing plate attached to an end of the polygonal frame, and a connection plug  31  is attached to ends of the wires. In this way, a polygonal branch module can be made. If the polygonal branch module can be used as a trunk module by using a fixing plate  81  instead of the above-mentioned fixing plate to fix the module to the ground or floor. 
     Another embodiment will now be described with reference to  FIGS. 5   q  and  5   r . Assembly space regions  12  and wire accommodation grooves  14  are not formed on three sides  42  of a triangular pillar  40  but a triangular internal space region  41  is formed in a center region of the triangular pillar  40 . Screw holes  58  are formed in the three sides  42  of the triangular pillar  40  so that screws can be tightened toward the internal space region  41 . Penetration holes (not shown) are formed from the sides  42  to the internal space region  41  so that when simple solar cell modules  22  are attached to the sides  42 , wires of the simple solar cell modules  22  can be put into the internal space region  41  through the penetration holes. 
     The triangular pillar  40  may be formed of metal, wood, plastic, vinyl resins, or a ceramic material such as concrete. The length and size of the triangular pillar  40  can be selected according to the size of a solar cell branch or trunk module to be made using the triangular pillar  40 . 
     In case of using the triangular pillar  40  to form a branch module, a fixing plate  24  is fixed to an end of the triangular pillar  40 , and in case of using the triangular pillar  40  to form a trunk module, a fixing plate  81  is fixed to an end of the triangular pillar  40  to put the triangular pillar  40  at an upright position. Module auxiliary frames  50  to which simple solar cell modules  22  are attached are fixed to sides  42  of the triangular pillar  40 . 
     The module auxiliary frames  50  are brought into contact with and applied to the sides  42  of the triangular pillar  40 . The width of the module auxiliary frames  50 , that is, the distance between ends  55  of the module auxiliary frames  50  is similar or equal to the width of the sides  42  so that the module auxiliary frames  50  can be easily attached to the sides  42 . The length of the module auxiliary frames  50  is equal to the length of the triangular pillar  40 , and the thickness of the module auxiliary frames  50  is about 10 mm to 20 mm. Back sides  54  of the module auxiliary frames  50  making contact with the sides  42  are flat, and assembly space regions  12  are formed by recessing front sides of the module auxiliary frames  50  toward the back sides  54 . Wire accommodation grooves  14  are formed in the assembly space regions  12 , and jaws  13  are formed on both sides of the assembly space regions  12 . Ends of the jaws  13  correspond to the ends  55 . 
     In the module auxiliary frames  50 , the assembly space regions  12  are lower than the ends  55 , and the jaws  13  are located inside the ends  55 . The wire accommodation grooves  14  are formed in the length direction of the assembly space regions  12  to receive wires, and screw assembly holes  53  are formed in the wire accommodation grooves  14  toward the back sides  54 . The screw assembly holes  53  are aligned with the screw holes  58  so that fixing screws  59  can be tightened therethrough. 
     The assembly space regions  12  of the module auxiliary frames  50  are provided to attach simple solar cell modules  22  to the assembly space regions  12 . First, the back sides  54  of the module auxiliary frames  50  are brought into contact with the sides  42  of the triangular pillar  40 , and fixing screws  59  are tightened in the screw assembly holes  53  of the module auxiliary frames  50  and the screw holes  58  of the triangular pillar  40  so as to fix the module auxiliary frames  50  to the sides  42  of the triangular pillar  40 . Then, simple solar cell modules  22  are attached to the assembly space regions  12 , and edges of the simple solar cell modules  22  are bonded to the jaws  13 . 
     Passages such as penetration holes (not shown) are formed to connect the wire accommodation grooves  14  of the module auxiliary frames  50  to the internal space region  41  of the triangular pillar  40  so as to introduce wires of the simple solar cell modules  22  into the internal space region  41  of the triangular pillar  40  through the penetration holes. 
     Referring to  FIGS. 5   q  and  5   r , if the angle of each end  55  of the module auxiliary frames  50  is a right angle, the ends  55  do not form triangle vertices after the module auxiliary frames  50  are attached to the triangular pillar  40 . This is the same when the triangular pillar  40  has any other polygonal shape such as triangular, pentagonal, and hexagonal shapes. 
     Referring to  FIGS. 6   s  and  6   t , unlike the above-described ends  55 , ends  55   b  of module auxiliary frames  50  are not perpendicular to back sides  54  but angled according to the polygonal shape (triangular shape) of the triangular pillar  40 . In the example, the ends  55   b  and the back sides  54  make an angle of 150 degrees so that the ends  55   b  are in contact with each other after the module auxiliary frames  50  are attached to the triangular pillar  40 . 
     The triangular pillar  40  may have any other polygonal shape such as quadrangular, pentagonal, and hexagonal shapes. This will now be described. 
     Referring to  FIGS. 7   u  and  7   v , an octagonal pillar  40   c  is shown. The angle between ends  55   b  and back sides  54  of module auxiliary frames  50  is determined applied to the shape of a polygonal pillar such as the octagonal pillar  40   c.  For example, the angle between the ends  55   b  and the back sides  54  is 150 degrees for a triangular pillar, 135 degrees for a quadrangular pillar, 126 degrees for a pentagonal pillar, 120 degrees for a hexagonal pillar, about 115 degrees for a heptagonal pillar, 112.5 degrees for an octagonal pillar, 110 degrees for a nonagonal pillar, and 108 degrees for a decagonal pillar. 
     Referring to  FIGS. 8   w  and  8   x , a circular pillar  40   d  is shown. In this case, back sides  54   b  of module auxiliary frames  50   b  are shaped according to the circumference of the circular pillar  40   d,  that is, the circumference of an outer side  42   b  of the circular pillar  40   d  so that when the back sides  54   b  can be stably attached to the side  42   b  of the circular pillar  40   d  without any gap. 
     Although the circular pillar  40   d  is circular, since assembly space regions  12  and jaws  13  of the module auxiliary frames  50   b  are flat and stepped, flat simple solar cell modules  22  can be attached to the assembly space regions  12 , and thus a polygonal shape can be obtained according to the number of the attached simple solar cell modules  22 . Referring to  FIGS. 8   w  and  8   x , eight module auxiliary frames  50   b  are used to form an octagonal shape, and the simple solar cell modules  22  are attached to eight sides of the octagonal shape. Ends  55   b  of the module auxiliary frames  50   b  form the vertices of the octagonal shape. Therefore, an octagonal pillar can be formed. 
     Referring to  FIGS. 9   y  and  9   z , a circular solar cell trunk module can be made using a circular pillar  40   d.  The outermost transparent plates of simple solar cell modules  22   c  attached to assembly space regions  12  of module auxiliary frames  50   b  are shaped in the form of a circular arc. 
     In the above description, the circular pillar  40   d  has the same diameter in the length direction thereof, that is, the same diameter at both ends thereof. However, if the circumference of the circular pillar  40   d  varies longitudinally because the circular pillar  40   d  has a large diameter at a lower end thereof and a relatively small diameter at an upper end thereof like a tapered utility pole, the width of the module auxiliary frames  50   b  may be varied in the length direction thereof according to the shape of the circular pillar  40   d.    
     That is, the width of the module auxiliary frames  50   b  is increased as it goes upward. It is apparent that the difference between the lower-end width and upper-end width of the module auxiliary frames  50   b  is determined in proportion to the difference between the lower-end diameter and the upper-end diameter of the circular pillar  40   d.    
     That is, if the circumference of the circular pillar  40   d  varies from the lower end to the upper end thereof like a tapered utility pole, the width of the module auxiliary frames  50   b  is also varied from the lower end to the upper end thereof according to the variation of the circumference of the circular pillar  40   d.    
     As described above, the ends  55   b  of the module auxiliary frames  50   b  may be varied in size with an upwardly or downwardly increasing width, and accordingly the assembly space regions  12  may be varied in size with an upwardly or downwardly increasing width. In this case, it is apparent that simple solar cell modules  22 , simple solar cell modules  22   c,  or sheets, solar cells, and transparent glass plates are varied in size according to the varying size of the assembly space regions  12 . 
     Another embodiment will now be described with reference to  FIG. 10   a   1  showing a plan view of a branch module  140  and  FIG. 10   b   1  showing a perspective view of the branch module  140 . The branch module  140  includes a branch module single frame  60  having one assembly space region  12  to which one simple solar cell module  22  can be attached. That is, the branch module  140  will be used as a branch module but will not be used as a trunk module. 
     The thickness of the branch module single frame  60  may be about 10 mm to 20 mm. The width of the branch module single frame  60 , that is, the distance between ends  65  of the branch module single frame  60  may be varied according to the size of a simple solar cell module  22  to be attached. Like in the case of the above-mentioned triangular frame  10 , if the with of a simple solar cell module  22  to be attached is 156 mm, the width of the assembly space region  12  may be about 160 mm. In this case, if the distance between the jaws  13  and the ends  65  is 20 mm at one size, the with of the branch module single frame  60  may be about 200 mm (=40 mm, the distances between the jaws  13  and the ends  65  at both sides, +160 mm, the width of the assembly space region  12 ). 
     The length of the branch module single frame  60  is determined according to the number of solar cells included in the simple solar cell module  22  to be attached to the assembly space region  12 . That is, a manufacture can determine the length of the branch module single frame  60 . 
     At least one wire accommodation groove  14  is formed in the assembly space region  12  on the front side of the branch module single frame  60 , and due to the jaws  13  inside the ends  65 , the assembly space region  12  has a recessed shape. One-piece part  64  is formed on the back side of the branch module single frame  60 , and a reinforcing frame  66  is formed in one piece with the one-piece part  64 . The reinforcing frame  66  has a circular shape and extends in the length direction of the branch module single frame  60 , and a circular internal space region  67  is formed in an center region of the reinforcing frame  66 . 
     A plurality of penetration holes are formed from the outside of the branch module single frame  60  to the internal space region  67  so that when a simple solar cell module  22  is attached to the assembly space region  12 , wires of the simple solar cell module  22  can be arranged, and bolt holes  68  are formed from the reinforcing frame  66  to the internal space region  67  so that when a fixing rod is inserted in the internal space region  67 , the fixing rod can be fixing by inserting bolts in the bolt holes  68  and tightening the bolts. 
     The branch module  140  is provided after a simple solar cell module  22  is attached to the assembly space region  12  of the branch module single frame  60  as described above. 
     When the branch module  140  is used, a fixing rod is inserted in the internal space region  67  of the branch module  140 , and the branch module  140  is fixed by tightening bolts through the bolt holes  68  in a state where the simple solar cell module  22  attached to the assembly space region  12  is oriented upward. 
     The fixing rod inserted in the internal space region  67  of the reinforcing frame  66  of the branch module  140  is a rod previously fixed to the outside of a pillar. That is, a tree-shaped solar cell module can be made by inserting the fixing rod in the internal space region  67  of the branch module  140  and tightening bolts through the bolt holes  68 . 
     In detail, a tree-shaped solar cell module can be provided by attaching fixing rods to the outside of a tree-shaped pillar like branches and coupling such branch modules  140  to the fixing rods. 
     Although the reinforcing frame  66  and the internal space region  67  are circular in the above description, the reinforcing frame  66  and the internal space region  67  may have a polygonal shape. In this case, a fixing rod to be inserted in the internal space region  67  may also have a circular shape or a polygonal shape corresponding to the shape of the internal space region  67 . 
       FIG. 11   c   1  is a plan view showing a branch module  150 , and  FIG. 11   d   1  is a perspective view showing the branch module  150 . The branch module  150  is a modified version of the branch module  140 . The branch module  150  includes a branch module dual frame  60   a  so that two simple solar cell modules  22  can be attached for one reinforcing frame  66 . The branch module dual frame  60   a  includes two assembly space regions  12  to which simple solar cell modules  22  can be attached. At a corner  63 , two jaws  13  makes an angle of 120 degrees like two branch module frames  60  are connected. 
     In other words, the branch module dual frame  60   a  includes two branch module frames  60  connected at an angle of 120 degrees. It is apparent that the angle between the two branch module frames  60  can have any other value smaller than or greater than 120 degrees. 
     The branch module dual frame  60   a  includes the two assembly space regions  12  and has an angle of 120 degrees at the corner  63  between the two assembly space regions  12 . A reinforcing frame  66  including an internal space region  67  protrudes from a one-piece part  64  of the back side of the branch module dual frame  60   a.  The reinforcing frame  66  is parallel with the assembly space regions  12  and has the same length as that of the assembly space regions  12 . In the branch module dual frame  60   a,  wire holes are formed from the assembly space regions  12  to the internal space region  67 , and a plurality of bolt holes  68  are formed so that the branch module  150  can be used in the same manner as that for the branch module  140 . 
       FIG. 12   e   1  is a plan view showing a branch module  160 , and  FIG. 12   f   1  is a perspective view showing the branch module  160 . The branch module  160  includes a branch module multiple frame  60   b  having three assembly space regions  12  to which simple solar cell modules  22  can be attached. The branch module multiple frame  60   b  is a combined version of the branch module single frame  60  and the branch module dual frame  60   a.  In other words, the branch module multiple frame  60   b  includes three branch module frames  60  that are connected to each other and has an angle of 135 degrees at each corner  63   a.  That is, that angle between the assembly space regions  12  of the branch module multiple frame  60   b  are 135 degrees. 
     A reinforcing frame  66  protrudes from a middle portion (one-piece part  64   a ) of the branch module multiple frame  60   b.  The reinforcing frame  66  is formed in one piece with the branch module multiple frame  60   b  in the length direction of the branch module multiple frame  60   b.  An internal space region  67  is formed in a center portion of the reinforcing frame  66 , and a gap  72  is formed in the length direction of the reinforcing frame  66  to open the internal space region  67 . Fixing taps  70  and  71  protrude from both sides of the gap  72  as fixing structures. A plurality of fixing bolt holes  73  are formed through sides of the fixing taps  70  and  71  so that if the fixing taps  70  and  71  are fastened by inserting fixing bolts  74  in the fixing bolt holes  73  and tightening the fixing bolts  74  and nuts, the internal space region  67  can be shrunk by the width of the gap  72  between the fixing taps  70  and  71  to fix a circular fixing rod inserted in the internal space region  67 . 
     After simple solar cell modules  22  are attached to the assembly space regions  12  of the branch module dual frame  60   a,  the branch module  160  can be used as a branch module of a tree-shaped solar cell module. 
       FIG. 13   g   1  is a plan view showing a branch module  170 , and  FIG. 13   h   1  is a perspective view showing the branch module  170 . The branch module  170  includes a branch module curve frame  60   d,  and the branch module curve frame  60   d  includes a assembly space region  12  having an arc shape. A plurality of wire accommodation grooves  14  are formed in the assembly space region  12   d,  and jaws  13  and ends  65   d  are higher than the assembly space region  12   d.    
     A reinforcing frame  66  extends from a one-piece part  64   d  formed on an arc-shaped middle portion of the back side of the branch module curve frame  60   d,  The reinforcing frame  66  is formed in one piece with the one-piece part  64   d  and has the same length as the one-piece part  64   d.  An internal space region  67  is formed in the reinforcing frame  66  in the length direction of the reinforcing frame  66 . 
     A gap  72  is formed in a portion of the reinforcing frame  66  to open the internal space region  67 , and fixing taps  70  and  71  are formed on both sides of the gap  72 . A plurality of fixing bolt holes  73  are regularly formed in sides of the fixing taps  70  and  71 , and thus the fixing taps  70  and  71  can be fastened by tightening fixing bolts  74  in the fixing bolt holes  73  to firmly fix a circular rod inserted in the internal space region  67 . That is, the internal space region  67  can be shrunk by the width of the gap  72  to fix a circular rod inserted in the internal space region  67 . 
     A simple solar cell module  22   d  to be attached to the assembly space region  12   d  of the branch module curve frame  60   d  may have an arc shape corresponding to the arc shape of the assembly space region  12   d.  For this, the simple solar cell module  22   d  may include thin-film solar cells, or the simple solar cell modules  22   d  may include crystalline solar cells which are formed of an arc-shaped wafer or are cut into small sizes by a cutting process. 
     The above-described branch modules and trunk modules may have a long length. In this case, the branch modules and the trunk modules may be straight or gradually curved in the length direction thereof so that a tree-shaped solar cell module having a straight shape or a freely curved shape can be made. 
     In addition, the branch modules and the trunk modules may be slightly twisted or may be slightly curved and twisted. 
     Straight branch modules and trunk modules may be used to form solar cell modules for industrial solar power generation, and slightly curved or twisted branch modules and trunk modules may be used to form solar cell modules shaped like landscaping trees for solar power generation harmonized with environments of downtown areas or residential areas. 
     An explanation will not be given about installation of the branch modules and trunk modules described with reference to  FIGS. 1 to 13 . 
     Simple solar cell modules  22  are attached to the assembly space regions  12  or the assembly space regions  12   d  of the above-described polygonal frame such as the triangular frame  10 , the quadrangular frame  10   a,  the hexagonal frame  10   b,  the octagonal frame  10   c,  and the circular frame  10 , and the polygonal pillar such as the triangular pillar  40 , the quadrangular pillar  40   b,  the octagonal pillar  40   c,  and the circular pillar  40   d.  As described above, if the fixing plate  24  is provided on an end of the polygonal frame or the polygonal pillar, the polygonal frame or pillar is used as a branch module, and if the fixing plate  81  is provided on an end of the polygonal frame or pillar, the polygonal frame or pillar is used as a trunk module. 
     The trunk module  200  will now be described in more detail with reference to  FIGS. 14 to 16 . The fixing plate  81  is provided on an end of the trunk module  200 , and a plurality of reinforcing plates  82  are used to support the fixing plate  81  and the trunk module  200 . Bolt holes are formed between the reinforcing plates  82 . 
     For fixing branch modules to the trunk module  200 , nut holes  84  are formed in the trunk module  200  at positions corresponding to the fixing holes  27  of the fixing plates  24  of the branch modules. 
     Connection wires  33  are provided at wire holes  80 , and connection sockets  34  are provided on ends of the connection wires  33 . The connection wires  33  are electrically connected in parallel or series to a main wire  38  accommodated in the internal cavity  16 , the internal cavity  16   d,  the internal space region  41 , the internal space region  41   b,  the internal space region  41   c,  or the internal space region  41   d  of the trunk module  200 . The main wire  38  may be pulled out to a lower side of the fixing plate  81 , and a connection plug  31  is provided on an end of the main wire  38 . 
     Since the trunk module  200  may be formed of a polygonal branch module or trunk module such as the triangular branch module  100 , the quadrangular branch module  110 , the rhombus branch module  120 , and the circular branch module  130 , the internal space of the trunk module  200  may be the internal cavity  16 , the internal cavity  16   d,  the internal space region  41 , the internal space region  41   b,  the internal space region  41   c,  or the internal space region  41   d.    
     A base  85  is supported in the ground by burying a lower portion of the base  85  in the ground surface layer  90 . The top surface of the base  85  is horizontal, and fixing bolts corresponding to bolt holes of the fixing plate  81  are disposed on the top surface of the base  85 . A connection wire  39  and a connection socket  34  are connected to a wire  89  buried in the ground. The wire  89  is connected to a controller such as a load-side inverter. 
     The connection plug  31  is connected to the connection socket  34 , and the fixing plate  81  of the trunk module  200  is placed on the fixing bolts  86  of the base  85 . Then, nuts are tightened to the fixing bolts  86 . In this way, the trunk module  200  can be installed. 
     Hereinafter, an explanation will now be given about a typical case where a tree-shaped solar cell module  400  is configured by a trunk module  200  and rhombus branch modules  120 . 
     Referring to  FIGS. 16 to 18 , the trunk module  200  includes the connection sockets  34  and the connection wires  33  for electric connection with wires of solar cells. Therefore, when the fixing plates  24  of the rhombus branch modules  120  are attached to the nut holes  84  of the trunk module  200 , the connection plugs  31  of the rhombus branch modules  120  are first connected to the connection sockets  34  of the trunk module  200 , and the connection plugs  31  and the connection sockets  34  are put inward through the wire holes  80  of the trunk module  200 . Then, the fixing holes  27  of the fixing plates  24  of the rhombus branch modules  120  are aligned with the nut holes  84 , the rhombus branch modules  120  are fixed to the trunk module  200  by tightening bolts through the fixing holes  27  and the nut holes  84 . In this way, the tree-shaped solar cell module  400  are assembled. 
     When the rhombus branch modules  120  are fixed to the nut holes  84  of the trunk module  200 , an adhesive (not shown) such as a silicone adhesive may be applied therebetween or o-rings may be disposed therebetween for sealing therebetween. Then, water may not permeate through the wire holes  80  and the nut holes  84  of the trunk module  200  and the wire hole  25  of the rhombus branch modules  120 . 
       FIG. 16  is an enlarge view showing the trunk module  200 ,  FIG. 17  is a front view showing the tree-shaped solar cell module  400  after installation, and  FIG. 18  is an enlarged perspective view showing the rhombus branch modules  120  of the tree-shaped solar cell module  400 . 
     The tree-shaped solar cell module  400  may be provided by attaching branch modules such as triangular branch modules  100 , quadrangular branch modules  110 , or rhombus branch modules  120  to the outside of the trunk module  200  like tree branches. The tree-shaped solar cell module  400  may include triangular branch modules  100 , quadrangular branch modules  110 , or rhombus branch modules  120 , or the tree-shaped solar cell module  400  includes combinations thereof. 
     Referring to  FIGS. 17 and 18 , in the tree-shaped solar cell module  400 , rhombus branch modules  120  of one layer are staggered with rhombus branch modules  120  of the next layer. That is, layers of the rhombus branch modules  120  or upper and lower layers of the rhombus branch modules  120  are staggered so as to be evenly exposed to sunlight. 
     Twig modules (not shown) similar or equal to the rhombus branch modules  120  may be attached to lateral sides of the rhombus branch modules  120  like tree twigs. In this case, the rhombus branch modules  120  may be easily swung by wind, and the power generation efficiency of the rhombus branch modules  120  and the trunk module  200  may be decreased because of shadows of the twig modules. In addition, the effect of power generation by the twig modules may be low as compared with the manufacturing costs thereof. Therefore, such twig modules may be used for the purpose of landscaping or the like. 
     For example, the tree-shaped solar cell module  400  can be installed at a desired place by digging the ground using a screw drill machine or excavator and burying a lower portion of the trunk module  200  in the ground. 
     In another example, after digging the ground as described above, a base  85  is partially buried in the ground, and the fixing plate  81  provided on the lower end of the trunk module  200  is placed on the base  85 . Then, the fixing plate  81  is fixed to the base  85  using bolts  86  and nuts  87 . Thereafter, the connection plugs  31  of the rhombus branch modules  120  are electrically connected to the connection sockets  34  of the trunk module  200 , and then after aligning the fixing holes  27  with the nut holes  84 , the rhombus branch modules  120  are fixed to the trunk module  200  using bolts. 
       FIGS. 19 ,  20 , and  21  show the case where rhombus branch modules  120  are fixed to a trunk module  200  using branch coupling parts  90 . The branch coupling parts  90  are used if it is difficult to form the nut holes  84  or the nut holes  84  are weak for attaching the rhombus branch modules  120 . In addition, the branch coupling parts  90  may be used when attaching rhombus branch modules  120  to a pillar instead of the trunk module  200 . 
     The branch coupling parts  90  are used in pairs, and the shape of the branch coupling parts  90  are different according to the shape of the trunk module  200 . An exemplary case where the trunk module  200  has a octagonal shape an the branch coupling parts  90  have a corresponding shape will now be explained. It is apparent that proper branch coupling parts  90  can be selected according to the shape of the trunk module  200  such as a circular shape and whether the lower end and upper end of the trunk module  200  is different or not. 
     Two or three branch coupling parts  90  may be used as a set around the trunk module  200 . In the exemplary case, two branch coupling parts  90  are used as a set. 
     In the case where the two branch coupling parts  90  are coupled to the trunk module  200  having an octagonal shape, the set of the two coupling parts  90  has an octagonal shape. That is, each of the branch coupling parts  90  has a half of the octagonal shape. In detail, each of the branch coupling parts  90  has a complete three sides and two half sides on both ends thereof, and coupling plates  91  protrude laterally from both ends of the branch coupling parts  90 . The coupling plates  91  are formed in one piece with the branch coupling parts  90 , and at least of coupling hole  95  is formed in each coupling plate  91 . When the branch coupling parts  90  are coupled, the coupling plates  91  are aligned. 
     The sides of the branch coupling parts  90  will now be referred to as connection portions  92 , and a wire hole  96  is formed in each connection portion  92  so that a connection socket  34  can be inserted. A plurality of nut holes  97  are formed around the wire hole  96  so that the fixing plate  24  of a rhombus branch module  120  or any other branch module can be fixed to the nut holes  97 . The nut holes  97  are positioned so that the nut holes  97  can be aligned with the fixing holes  27  of the fixing plate  24  for inserting bolts therein. 
     If the trunk module  200  has a circular shape, it is apparent that the branch coupling parts  90  have a semicircular shape, and the number of the wire holes  96  and the nut holes  97  are determined according to the number of branch modules to be attached to the branch coupling parts  90 . That is, according to the shape of the trunk module  200 , branch coupling parts  90  having proper shapes such as semi polygonal shapes may be used. 
     Referring to  FIG. 22 , branch coupling parts  90  are coupled in pairs around a trunk module  200 , and coupling plates  91  of the branch coupling parts  90  are fastened by inserting coupling bolts  98  in coupling holes  95  and tightening the coupling bolts  98  with coupling nuts  99 . In this way, a tree-shaped solar cell module  500  is assembled. 
     Referring to  FIG. 23 , a trunk module  200  includes a one-piece supports  35  and fixing plates  36  for attaching branch modules such as quadrangular branch modules  110  to the trunk module  200 . The one-piece supports  35  and the fixing plates  36  are arranged on the outer side of the trunk module  200  so that quadrangular branch modules  110  can be attached thereto. 
     The one-piece supports  35  may have a polygonal shape or circular shape. The one-piece supports  35  may be oriented in predetermined directions in which the quadrangular branch modules  110  will be attached. The fixing plates  36  have a rectangular shape in the drawing. However, the fixing plates  36  have any other polygonal shape or a circular shape. 
     If the trunk module  200  is formed of a metal, the one-piece supports  35  and the fixing plates  36  may be formed of a metal and fixed to the trunk module  200  by welding. 
     If the trunk module  200  is formed of concrete and steel reinforcing bars, the one-piece supports  35  formed of a metal may be welded to the reinforcing bars, and then concrete may be introduced into a mould to form the trunk module  200  with the one-piece supports  35  and the fixing plates  36 . 
     Wire holes  37  are in the front sides of the fixing plates  36 . The wires holes  37  are connected to an inner space of the trunk module  200  through an inner space of the one-piece supports  35 . Connection wires  33  to which connection sockets  34  are attached are pulled out through the wire holes  37 . 
     As shown in  FIG. 24 , equipment such as street facilities may be installed on a tree-shaped solar cell module of the present invention. In the drawings, a lightening rod  1 , utility pole crossarms  2 , a transformer, a traffic lights  8 , and a streetlamp  9  are installed on an upper portion of a trunk module  200  of a tree-shaped solar cell module  600 . In addition, flowerpots may be disposed around the lower end of the trunk module  200 . 
     In other words, the tree-shaped solar cell module  600  is provided by adding a lightening rod  1 , utility pole crossarms  2 , a transformer, traffic lights  8 , and a streetlamp  9  to the upper portion of the trunk module  200  of the tree-shaped solar cell module  400 , and disposing flowerpots around the lower end of the trunk module  200 . 
     Since the utility pole crossarms  2  also called metal arms, steel arms, or iron shoulders are fixed to an upper portion of the trunk module  200  of the tree-shaped solar cell module  600 , electric wires can be supported by the tree-shaped solar cell module  600 , and thus the tree-shaped solar cell module  600  can be used as a utility pole on a street as well as being used for solar power generation. 
     The tree-shaped solar cell module  600  can be installed on a place where a utility pole is not installed, and electricity generated by the tree-shaped solar cell module  600  can be supplied to electricity equipment of an electric power company so that costs necessary to install a utility pole can be saved. Electricity generated from sunlight by the tree-shaped solar cell module  600  can be converted into AC power using an inverter and boosted in voltage using the transformer, and then the AC power can be transmitted through electric wires supported on the crossarms  2 . 
     For the purpose of solar power generation of the present invention, solar cells may be attached to the crossarms  2  or a traffic light support bar  7  in the same method as that used to attach solar cells to the quadrangular branch modules  110 . 
     The traffic light support bar  7  may be fixed to the trunk module  200  using a traffic light coupling part  6  at a height of about 5 mm to about 7 mm from the ground which is the height where traffic lights are installed, and the traffic lights  8  may be attached to an end of the traffic light support bar  7 . 
     As described above, the tree-shaped solar cell module  600  can be installed on a street and used as a street tree, a utility pole, and traffic lights as well as being used for solar power generation. In addition, other structures such as a load sign, a unmanned camera, and the streetlamp  9  can be attached to the tree-shaped solar cell module  600 . 
       FIG. 25  is a view showing a tree-shaped solar cell module  650  in which flowerpots  77  having internal cavities are fixed to a trunk module  200  at a height of about 3 m to about 5 m from the ground to put roots of trees in the flowerpots  77 . That is, the tree-shaped solar cell module  650  can used for planting and power generation. This will now be described in more detail. 
     Small trees may be planted in the flowerpots  77 . The flowerpots  77  are oriented upward so that the internal cavities of the flowerpots  77  can be open upward, and fixing parts  78  of the flowerpots  77  may be fixed to the trunk module  200  by welding or using bolts. The internal cavities may be filled with soil, humus, ceramic powder, or the like for planting trees. 
     The flowerpots  77  may have a circular shape or a polygonal shape and formed of a material such as metals, ceramic materials, and plastics. 
     Like actual branches of a tree, the flowerpots  77  may be fixed to the trunk module  200  at angles of 0 to 180 degrees with respect to the trunk module  200 . 
     Owing to alive trees planted in the flowerpots  77  fixed to the trunk module  200 , the tree-shaped solar cell module  650  can appear like a street tree. 
     If the tree-shaped solar cell module  650  is installed on a street, people can see trees planted in the flowerpots  77 , and electricity can be generated from solar cells of upper rhombus branch modules  120  of the tree-shaped solar cell module  650 . 
     Although not shown in the drawing, so as to provide environments where the trees planted in the flowerpots  77  can grow well, penetration holes are formed in center portions of the fixing parts  78  to connect the internal cavities of the flowerpots  77  to an internal cavity of the trunk module  200 , and bundles of fine tubes such as capillary tubes are inserted in the penetration holes in a manner such that the upper ends of the capillary tube bundles are placed at the lower ends of the internal cavities of the flowerpots  77  and the lower ends of the capillary tube bundles are pulled outward through the lower end of the internal cavity of the trunk module  200 . 
     When the tree-shaped solar cell module  650  is installed, the lower ends of the capillary tube bundles pulled outward through the lower end of the trunk module  200  are deeply buried in the ground so that water can be pulled upward from the ground to the trees planted in the flowerpots  77  through the capillary tube bundles. 
     The capillary tube bundles each having fine tubes may be formed of a material such as stainless metals, ceramic materials such as glass, plastics, and vinyl resins. 
       FIG. 26   k   1  is a perspective view showing a tree-shaped solar cell module  700 , and  FIG. 26   m   1  is an enlarged view showing a portion of a branch module  140 . In the tree-shaped solar cell module  700 , the above-described branch modules  140  are fixed to a pillar  45 . The pillar  45  may be a metal pillar such as an iron pillar or a concrete pillar. Support rods fixed to the pillar  45  are inserted in internal space regions  67  of the branch modules  140  and are fixed using bolts. In this way, the tree-shaped solar cell module  700  can be assembled and used for solar power generation. 
       FIG. 27   n   1  is a perspective view showing a tree-shaped solar cell module  710 , and  FIG. 27   p   1  is an enlarged view showing a portion of a branch module  150 . In the tree-shaped solar cell module  710 , the above-described branch modules  150  are fixed to a pillar  45 . Support rods fixed to the pillar  45  are inserted in internal space regions  67  of the branch modules  150  and are fixed using bolts. In this way, the tree-shaped solar cell module  710  can be assembled and used for solar power generation. 
       FIG. 28   q   1  is a perspective view showing a tree-shaped solar cell module  720 , and  FIG. 28   r   1  is an enlarged view showing a portion of a branch module  160 . In the tree-shaped solar cell module  720 , the above-described branch modules  160  are fixed to a pillar  45 . Support rods fixed to the pillar  45  are inserted in internal space regions  67  of the branch modules  160  and are fixed using bolts. In this way, the tree-shaped solar cell module  720  can be assembled and used for solar power generation. 
       FIG. 29   s   1  is a perspective view showing a tree-shaped solar cell module  730 , and  FIG. 29   t   1  is an enlarged view showing a portion of a branch module  170 . In the tree-shaped solar cell module  730 , the above-described branch modules  170  are fixed to a pillar  45 . Support rods fixed to the pillar  45  are inserted in internal space regions  67  of the branch modules  170  and are fixed using bolts. In this way, the tree-shaped solar cell module  730  can be assembled and used for solar power generation. 
     Referring to  FIGS. 29 and 30 , in the tree-shaped solar cell module  730 , four branch modules  170  are radially arranged on each of six layers, and the layers are sequentially twisted 30 degrees. Referring to the plan view of  FIG. 30 , the branch modules  170  are overlapped with each other at the center region and are separated from each other at the circumferential region. 
     Referring to  FIGS. 31 and 32 , in the tree-shaped solar cell module  730 , branch modules  170  are arranged in twelve layers, and each layers are twisted 15 degrees. Referring to the plan view of  FIG. 32 , the branch modules  170  are arranged without any gap at the circumferential region. Therefore, center portions of the branch modules  170  receive sunlight partially, and circumferential portions of the branch modules  170  receive sunlight fully. 
     Referring to  FIGS. 33   t ,  33   u , and  33   v , when the above-described branch modules are fixed to a trunk module, the branch modules can be oriented upward, horizontally, or downward. 
     Referring to  FIG. 33   t , triangular branch modules  100 , quadrangular branch modules  110 , rhombus branch modules  120 , and circular branch modules  130  are upwardly fixed to fixing parts of a trunk module  200 . Referring to  FIG. 33   u , such branch modules are horizontally oriented, and referring to  FIG. 33   v , such branch modules are downwardly oriented. 
     The above-described tree-shaped solar cell modules do not have solar cells corresponding to leaves but has solar cells on branch modules so that sunlight can go deep into the branch modules and trunk module for efficient power generation. In addition, since the tree-shaped solar cell modules do not have twigs and leaves, the tree-shaped solar cell modules can resist against strong wind. Furthermore, solar cells of the tree-shaped solar cell modules are disposed at high positions, power generation efficiency may not be reduced or less reduced by geothermal heat in desert regions. In other words, power generation efficiency of the tree-shaped solar cell modules may be higher than other solar cell modules. 
     Since the tree-shaped solar cell modules can be installed between small trees even on steep hills, a solar power plant can be constructed without destroying the natural environment. In addition, although the tree-shaped solar cell modules are installed on farmland, farming is possible between the tree-shaped solar cell modules. For example, pretty large crops such as fruit trees and corns can be grown between the tree-shaped solar cell modules. That is, almost all kinds of farming may be possible between the tree-shaped solar cell modules. 
     If the tree-shaped solar cell modules are installed in desert regions of China, since the tree-shaped solar cell modules weaken winds, less sand may be blown to delay the progress of desertification, and grassland may increase.