Patent Publication Number: US-2012037214-A1

Title: Solar cell module, solar cell attachment stand, photovoltaic power generating system

Description:
TECHNICAL FIELD 
     The present invention relates to a solar cell module, a solar cell attachment stand, and a photovoltaic power generating system. 
     DESCRIPTION OF THE BACKGROUND ART 
     In conventional systems of this kind, a solar cell module in which four sides of a solar cell panel are held with a frame member has been used. This is because the solar cell panel is mainly made of a substrate made of glass and the like, and thus the solar cell panel itself is brittle. In order to make up for this disadvantage, it is effective to protect the four sides of the solar cell panel with the frame member. 
     Also, since it is difficult to directly install the solar cell panel having such brittleness on a roof and the like, it is preferable that the solar cell panel be held with the frame member, and the frame member be installed and secured on the roof and the like. 
     For example, patent document 1 discloses a system in which the four sides of a solar cell panel are held with a frame member, and the four corners of the frame member are provided with leg portions wherein two front leg portions are shorter than two rear leg portions to support the solar cell panel in a slanted manner. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Patent document 1: JP1999-177115A 
     SUMMARY OF INVENTION 
     Problems to be Solved by the Invention 
     Unfortunately, the frame member holding the four sides of the solar cell panel is a rectangular frame, has a large piece-part count, and is complicated in shape, which makes difficult the attachment work with respect to the four sides of the solar cell panel. This has served as one of the causes of difficulty in a reduction in cost of the solar cell panel. 
     The present invention has been made to solve the above problems, it is an object of the present invention to provide a solar cell module, a solar cell attachment stand, and a photovoltaic power generating system that protect a solar cell panel and facilitate the attachment of the solar cell panel on a roof and the like, even without use of a frame member to hold the four sides of the solar cell panel. 
     Means of Solving the Problems 
     According to one aspect of the present invention, a solar cell module includes a solar cell panel and a reinforcing member. The reinforcing member is adhered to a rear surface of the solar cell panel and secured across opposing two sides of the solar cell panel. The reinforcing member includes an engagement portion protruding from a rear surface side of the reinforcing member. 
     Thus, a reinforcing member that is secured across opposing two sides of the solar cell panel is adhered and secured on the rear surface of the solar cell panel. This greatly improves the strength of the solar cell panel compared with the strength of the solar cell panel as a single entity. 
     An engagement portion protruding from the rear surface side of the reinforcing member is provided. The engagement portion is engaged with a stand or the like, thus installing the solar cell module. 
     Further, the solar cell module has a simple structure, with the reinforcing member merely adhered to the rear surface of the solar cell panel. This reduces the piece-part count and facilitates the attempt to reduce weight and cost of the solar cell module. 
     In the solar cell module according to the one aspect of the present invention, the reinforcing member may further include hooking portions bent at both ends of the reinforcing member. The reinforcing member may be secured on the rear surface of the solar cell panel with the opposing two sides of the solar cell panel held between the hooking portions at both ends of the reinforcing member. 
     The hooking portions of reinforcing bars protrude beyond the opposing two sides of the solar cell panel. Hence, when the solar cell module is placed on the ground or placed upright on a platform, the hooking portions directly contact the ground or the platform, which makes the sides of the solar cell panel detached and slightly afloat off the ground or the platform. This prevents chipping and damage to the sides of the solar cell panel. 
     In the solar cell module according to the one aspect of the present invention, the hooking portions at both ends of the reinforcing member each may have a height that is lower than a thickness of the solar cell panel. 
     This ensures that the hooking portions prevented from being a hindrance even when the solar cell panel is pressed at the portion of the reinforcing member. 
     The solar cell module according to the one aspect of the present invention may further include a shock absorbing member interposed between portions at both ends of the reinforcing member and the opposing two sides of the solar cell panel. 
     The shock absorbing member alleviates a shock, if any, on the end portions of the reinforcing member, thus preventing damage to the solar cell panel. 
     In the solar cell module according to the one aspect of the present invention, the solar cell panel may include a thin-film semiconductor layer on a substrate. The thin-film semiconductor may be configured to carry out photoelectric conversion. 
     As the substrate, a glass plate is oftentimes employed in many cases. Since the strength of the substrate is low, applying the prevent invention is effective. 
     In the solar cell module according to the one aspect of the present invention, the reinforcing member may include side portions bent at the both sides of the reinforcing member. 
     Thus, side portions bent at the both sides of the reinforcing member are formed. This improves the bending strength of the reinforcing member and the strength of the solar cell module. 
     According to another aspect of present invention, a solar cell attachment stand to support a solar cell panel includes a reinforcing member, at least one placing member, and fastening means. The reinforcing member is superimposed on a rear surface of the solar cell panel and secured across opposing two sides of the solar cell panel. On the at least one placing member, the reinforcing member on the rear surface of the solar cell panel is placed and secured. The fastening means is for fastening the placing member to the reinforcing member on the rear surface of the solar cell panel. The placing member and the reinforcing member on the rear surface of the solar cell panel include engagement portions engaged with one another. 
     Thus, the reinforcing member on the rear surface of the solar cell panel is placed on the placing member, and the reinforcing member on the rear surface of the solar cell panel and the placing member are fastened to one another. This secures the solar cell panel. Additionally, the reinforcing member on the rear surface of the solar cell panel and the placing member include engagement portions engaged with one another. This facilitates the positioning of the solar cell panel on the placing member. 
     In the solar cell attachment stand according to the other aspect of the present invention, the reinforcing member may further include hooking portions bent at both ends of the reinforcing member. The reinforcing member may be secured on the rear surface of the solar cell panel with the opposing two sides of the solar cell panel held between the hooking portions at both ends of the reinforcing member. 
     In the solar cell attachment stand according to the other aspect of the present invention, the hooking portions at both ends of the reinforcing member each may have a height that is lower than a thickness of the solar cell panel. 
     In the solar cell attachment stand according to the other aspect of the present invention, a solar cell module including the reinforcing member integrally adhered to the rear surface of the solar cell panel may be used. 
     The solar cell attachment stand according to the other aspect of the present invention may further include a shock absorbing member interposed between portions at both ends of the reinforcing member and the opposing two sides of the solar cell panel. 
     The solar cell attachment stand according to the other aspect of the present invention may further include a plurality of crosspieces disposed in parallel to each other with a distance provided therebetween. The distance may be at least same as a separation distance between the opposing two sides of the solar cell panel. The at least one placing member may include a plurality of placing members movably supported on the respective crosspieces in a solar cell panel aligning direction. A plurality of solar cell panels may be disposed between the crosspieces. The placing members may be movable to adjust positions of the placing members to positions of reinforcing members of adjacent solar cell panels among the plurality of solar cell panels. The engagement portion of each of the placing members and the engagement portion of each of the reinforcing members on the rear surface of the solar cell panel may be engaged with one another by fastening of the fastening means. 
     The movability of the placing members provides a tolerance to the positioning of the solar cell module, which facilitates the installment of the solar cell module. 
     In the solar cell attachment stand according to the other aspect of the present invention, the reinforcing member may include side portions bent at the both sides of the reinforcing member. 
     Thus, side portions bent at the both sides of the reinforcing member are formed. This improves the bending strength of the reinforcing member, the strength of the solar cell module, and further the strength of the solar cell attachment stand. 
     According to still another aspect of the present invention, a photovoltaic power generating system includes the solar cell attachment stand according to the other aspect of the present invention. 
     This photovoltaic power generating system facilitates the installation work of a large number of solar cell panels and ensures a drastic cost reduction. 
     Effects of the Invention 
     In the aspects of the present invention, a reinforcing member secured across opposing two sides of the solar cell panel is adhered and secured on the rear surface of the solar cell panel. This improves the strength of the solar cell panel compared with the strength of the solar cell panel as a single entity. 
     Additionally, an engagement portion protruding from the rear surface side of the reinforcing member is provided. The engagement portion is engaged with a stand or the like, thus installing the solar cell module. This facilitates the installation work of a large number of solar cell panels and ensures a drastic cost reduction. 
     Further, the solar cell module has a simple structure, with the reinforcing member merely adhered to the rear surface of the solar cell panel. This reduces the piece-part count and facilitates the attempt to reduce weight and cost of the solar cell module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       [ FIG. 1 ]  FIG. 1  is a perspective view of a solar cell module according to a first embodiment of the present invention. 
       [ FIG. 2 ]  FIG. 2  is a partially enlarged cross-sectional view of the solar cell module shown in  FIG. 1 . 
       [FIG  3 ]  FIG. 3  is a partially enlarged and exploded perspective view of the solar cell module shown in  FIG. 1 . 
       [FIG  4 ]  FIG. 4  is a perspective view of a solar cell attachment stand according to an embodiment of the present invention. 
       [ FIG. 5 ]  FIG. 5  is a partially enlarged perspective view of the solar cell attachment stand shown in  FIG. 4 . 
       [FIG  6 ]  FIG. 6  is a side view of an attachment stand unit of the solar cell attachment stand shown in  FIG. 4 . 
       [ FIG. 7 ]  FIG. 7  is an exploded perspective view of a center attachment stand unit of attachment stand units of the solar cell attachment stand shown in  FIG. 4 , as viewed from an upward direction, wherein side portions of solar cell modules are attached to the center attachment stand unit. 
       [ FIG. 8 ]  FIG. 8  is an exploded cross-sectional view showing the state of  FIG. 7 . 
       [FIG  9 ]  FIG. 9  is a cross-sectional view showing the state of  FIG. 7 . 
       [FIG  10 ]  FIG. 10  is a perspective view showing the state of  FIG. 7 , as viewed from a downward direction. 
       [FIG  11 ]  FIG. 11  is a perspective view of a part of a crosspiece of the attachment stand unit shown in  FIG. 6 . 
       [FIG  12 ]  FIG. 12  is a perspective view of a securing fitting of the attachment stand unit shown in  FIG. 6 . 
       [FIG  13 ]  FIG. 13  is a perspective view of a placing fitting of the attachment stand unit shown in  FIG. 6 . 
       [FIG  14 ]  FIG. 14  is a plan view of the placing fitting shown in  FIG. 13  in bent state. 
       [FIG  15 ]  FIG. 15  is a perspective view of the placing fitting shown in  FIG. 13  in bent state, as viewed from a front side. 
       [FIG  16 ]  FIG. 16  is a perspective view of the placing fitting shown in  FIG. 13  in bent state, as viewed from a back side. 
       [ FIG. 17 ]  FIG. 17  is a perspective view of the crosspiece with the securing fitting and the placing fitting attached. 
       [FIG  18 ]  FIG. 18  is a perspective view of the crosspiece illustrating a procedure for attaching the placing fitting to the crosspiece. 
       [ FIG. 19 ]  FIG. 19  is a perspective view of the crosspiece illustrating a continuation of the procedure shown in  FIG. 18 . 
       [ FIG. 20 ]  FIG. 20  is a perspective view of the crosspiece illustrating a continuation of the procedure shown in  FIG. 19 . 
       [FIG  21 ]  FIG. 21  is a perspective view of the crosspiece illustrating a continuation of the procedure shown in  FIG. 20 . 
       [FIG  22 ]  FIG. 22  is a perspective view of a solar cell module according to a second embodiment of the present invention. [FIG  23 ]  FIG. 23  is a partially enlarged cross-sectional view of the solar cell module shown in  FIG. 22 . 
       [FIG  24 ]  FIG. 24  is a partially enlarged and exploded perspective view of the solar cell module shown in  FIG. 22 . 
       [ FIG. 25 ]  FIG. 25  is a perspective view of a center attachment stand unit of attachment stand units of the solar cell attachment stand shown in  FIG. 4 , as viewed from a downward direction, wherein side portions of the solar cell modules shown in  FIG. 22  are attached to the center attachment stand unit. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     Embodiments of the present invention will be described below in detail by referring to the accompanying drawings. 
       FIG. 1  is a perspective view of a solar cell module according to a first embodiment of the present invention.  FIG. 2  is a partially enlarged cross-sectional view of the solar cell module according to an embodiment of the present invention.  FIG. 3  is a partially enlarged and exploded perspective view of the solar cell module according to an embodiment of the present invention. 
     As clearly seen from  FIGS. 1 to 3 , a solar cell module  2  includes a solar cell panel  20  and two reinforcing bars  21 . The two reinforcing bars  21  are disposed to laterally cross the solar cell panel  20  and superimposed and adhered on the rear surface of the solar cell panel  20 . 
     The solar cell panel  20  includes a transparent substrate such as of glass on which a thin-film semiconductor layer that carries out photoelectric conversion, an electrode film that transmits electric power, and the like are layered. The thin-film semiconductor layer, the electrode film, and the like are covered with a rear surface protective layer (also referred to as a back film or a back skin) and the like. 
     To each of opposing two sides  20   a  of the solar cell panel  20 , an elastic tape  22  is adhered for shock absorption. The elastic tape  22  covers: the end surfaces of the opposing two sides  20   a  of the solar cell panel  20 ; and a peripheral edge portion of the front surface and a peripheral edge portion of the rear surface of the solar cell panel  20 , the peripheral edge portions being along the two sides  20   a.    
     Each of the reinforcing bar  21  is a rectangular and flat plate having approximately the same length as the lateral width of the solar cell panel  20 . Both end portions of each reinforcing bar  21  are bent upwardly to form a hooking portion  21  a of each reinforcing bar  21 . U-shaped notches are formed adjacent to both ends of the reinforcing bar  21 , and the U-shaped parts are bent downwardly to form protruding engagement portions  21   b.  An example of the reinforcing bar  21  is made of a steel plate that is cut, bent, and subjected to plating. 
     An adhesive is applied to an upper surface  21   c  of the reinforcing bar  21 , which is on the side where the hooking portions  21   a  protrude. The upper surface  21   c  of the reinforcing bar  21  is superimposed and pressed on the rear surface of the solar cell panel  20 . The opposing two sides  20   a  of the solar cell panel  20  are held between the hooking portions  21   a  of the reinforcing bar  21 , so that the reinforcing bar  21  is secured on the rear surface of the solar cell panel  20 . Consequently, the elastic tape  22  is compressed on the rear surface of the solar cell panel  20 , and the rear surface of the solar cell panel  20  is uniformly adhered to the upper surface  21   c  of the reinforcing bar  21  via an adhesive layer. 
     The height of each hooking portion  21   a  of the reinforcing bar  21  is lower than the thickness of the solar cell panel  20 . This is for the purpose of holding the solar cell panel  20  directly with a securing fitting  3 , as described later. 
     In this respect, the solar cell panel  20  is mainly made of a substrate such as of glass, which makes the solar cell panel  20  brittle and low in strength. Additionally, when a thin-film semiconductor layer is formed on the substrate by chemical vapor reaction (CVD), the substrate is exposed to a high temperature, which further degrades the strength of the substrate. Even with the use of, for example, tempered glass as the substrate, the tempered glass is degraded in strength after exposure to a high temperature. Thus, the tempered glass fails to maintain its original strength. 
     In view of this, it is conventional practice to protect the four sides of the solar cell panel by a frame member. However, the rectangular frame member is complicated in shape and has a large piece-part count, which makes difficult the attachment work with respect to the four sides of the solar cell panel. This has been a cause of difficulty in a reduction in cost of the solar cell panel. It is also common practice to put two pieces of glass together in order to improve the strength of the solar cell panel. This, however, greatly increases the weight of the solar cell panel, which has increased the cost of the solar cell panel. 
     In contrast, in the solar cell module  2  according to this embodiment of the present invention, two reinforcing bars  21  are adhered and secured on the rear surface of the solar cell panel  20 , thereby improving the strength. The reinforcing bars  21  are simple in shape or structure and easily attachable. Further, a single piece of glass can be used to constitute the substrate, which eliminates the heaviness of the solar cell module  2  and facilitates the attempt to reduce the weight and cost of the solar cell module  2 . 
     Each of the reinforcing bars  21  is made of a steel plate or the like and therefore has high flexural rigidity. This sufficiently increases the flexural rigidity of the solar cell module  2  compared with the solar cell panel  20  as a single entity. For example, when wind pressure acts on the solar cell panel  20 , the single solar cell panel  20  as a single entity might not sufficiently strong against the wind pressure, whereas with the two reinforcing bars  21  adhered and secured on the rear surface of the solar cell panel  20 , the solar cell panel  20  is reinforced to a degree enough to withstand the wind pressure. 
     Additionally, parts of the opposing two sides  20   a  of the solar cell panel  20  are protected by the hooking portions  21   a  of each reinforcing bar  21 . The hooking portions  21   a  protrude beyond the opposing two sides  20   a  of the solar cell panel  20 . Hence, when the solar cell module  2  is placed on the ground or placed upright on a platform, the hooking portions  21   a  directly contact the ground or the platform, which makes the opposing two sides  20   a  of the solar cell panel  20  detached and slightly afloat off the ground or the platform. This prevents chipping and damage to the sides  20   a  of the solar cell panel  20 . 
     Additionally, the elastic tape  22  is interposed between each of the opposing two sides  20   a  of the solar cell panel  20  and each of the hooking portions  21   a  of the reinforcing bar  21 . Even if the hooking portions  21   a  of the reinforcing bar  21  bump into the ground or the platform, the elastic tape  22  alleviates an associated shock. This also prevents chipping and damage to the sides  20   a  of the solar cell panel  20 . 
     Further, as described later, when the solar cell panel  20  is installed on an attachment stand, the reinforcing bar  21  parts of the solar cell module  2  are fastened. This ensures that not all the fastening force acts on the solar cell panel  20  itself, which in turn ensures firm support of the solar cell module  2  without chipping and damage to the solar cell panel  20 . 
     Thus, as in the solar cell module  2  according to this embodiment of the present invention, adhering and securing the two reinforcing bars  21  to the rear surface of the solar cell panel  20  sufficiently protects the solar cell panel  20  and sufficiently increases the strength of the solar cell module  2 . 
       FIG. 4  is a perspective view of a solar cell attachment stand according to an embodiment of the present invention.  FIG. 5  is a partially enlarged perspective view of the solar cell attachment stand according to an embodiment of the present invention.  FIG. 6  is a side view of an attachment stand unit of the solar cell attachment stand according to an embodiment of the present invention. 
     The solar cell attachment stand  1  is for the purpose of supporting the solar cell module  2  of  FIGS. 1 to 3 . The solar cell attachment stand  1  uses three attachment stand units  10 , one of which is shown in  FIG. 6 . The attachment stand units  10  are arranged next to each other on a roof, the ground, or the like. As shown in  FIG. 4 , four solar cell modules  2  are mounted and secured on the attachment stand units  10 . 
     As shown in  FIG. 6 , each attachment stand unit  10  includes a crosspiece  11  and a support  16 , and has a generally triangular shape in side view. Specifically, each attachment stand unit  10  is built with the slanted crosspiece  11  and the support  16  that is slanted conversely relative to the crosspiece  11  and that has a top end secured to the crosspiece  11  approximately at a position of one-fourth of the length of the crosspiece  11  from the top end thereof. 
     More specifically, a front bracket  17  and a rear bracket  18  are installed and secured, with a predetermined distance therebetween, on a horizontal base surface such as the ground and a flat roof. A top end portion  11   a  of the crosspiece  11  is coupled and secured on the front bracket  17 , while the support  16  is secured to the rear bracket  18  and to the crosspiece  11  at a position of one-fourth of the length of the crosspiece  11  from the top end thereof. 
     Through the crosspiece  11 , only the top end portion  11   a  has a U-shaped cross-section, while the range from the vicinity of the top end portion  11   a  to the rear end has a top hat-shaped cross-section (see  FIG. 8 ). Through the support  16 , only the upper end portion has a U-shaped cross-section, while the range from the vicinity of the upper end portion to the lower end of the support  16  has a top hat-shaped cross-section. 
     The front bracket  17 , the rear bracket  18 , the crosspiece  11 , and the support  16  are each made of a steel plate that is cut, bent, and subjected to plating. 
     As clearly seen from  FIG. 4 , three attachment stand units  10  are arranged next to each other at intervals approximately equal to the width of the solar cell module  2 . Two solar cell panels  2  are disposed vertically next to each other between the crosspiece  11  of the left attachment stand unit  10  and the crosspiece  11  of the center attachment stand unit  10 . Another two the solar cell panels  2  are disposed vertically next to each other between the crosspiece  11  of the right attachment stand units  10  and the crosspiece  11  of the center attachment stand units  10 . A total of four solar cell panels  2  are placed and attached on top plates  12  of the crosspieces  11  of the attachment stand units  10 . 
     Side portions of the two, upper and lower solar cell modules  2  are placed and attached on the top plate  12  of the crosspiece  11  of the left attachment stand unit  10 . Similarly, side portions of the two, upper and lower solar cell modules  2  are placed and attached on the top plate  12  of the crosspiece  11  of the right attachment stand unit  10 . Further, the other side portions of the two, upper and lower solar cell modules  2  both on the left side and the right side are placed and attached on the top plate  12  of the crosspiece  11  of the center attachment stand unit  10 . 
     In order to secure each solar cell module  2  at two positions on each of the side portions, a total of four sets of securing fittings  3  and placing fittings  4  are used (as shown in  FIGS. 7 to 10 ). Regarding the left and right solar cell modules  2  disposed on the top plate  12  of the crosspiece  11  of the center attachment stand unit  10 , two sets of securing fittings  3  and placing fittings  4  are commonly used. That is, two sets of securing fittings  3  and placing fittings  4  simultaneously secure the side portions of the left and right solar cell modules  2 . 
     Next, a schematic description will be made with respect to an attachment structure of the solar cell module  2  to the crosspiece  11  of the attachment stand unit  10  in the solar cell attachment stand  1  of this embodiment. In the following description, the longitudinal direction of the crosspiece  11  of the attachment stand unit  10  is assumed the front-rear direction; the direction in which the three attachment stand units  10  are arranged next to each other is assumed the left-right direction; the direction in which the upper surface of the solar cell module  2  is exposed is assumed the upward direction; and the direction in which the rear surface of the solar cell module  2  is exposed is assumed the downward direction. 
       FIG. 7  is an exploded perspective view of the center attachment stand unit  10 , as viewed from the upward direction, wherein the side portions of the left and right solar cell modules  2  are attached to the crosspiece  11  of the center attachment stand unit  10 .  FIGS. 8 and 9  are respectively an exploded cross-sectional view and a cross-sectional view showing the state of  FIG. 7 .  FIG. 10  is a perspective view of the solar cell module  2  showing the state of  FIG. 7 , as viewed from the downward direction. It is noted that the solar cell panels  20  and the reinforcing bar  21  are separately shown in  FIGS. 7 and 10 . 
     As shown in  FIGS. 7 to 10 , the left and right solar cell modules  2  are attached on the top plate  12  of the crosspiece  11  of the center attachment stand unit  10  using the securing fitting  3  abutting the light receiving surface side of the solar cell module  2 , the placing fitting  4  abutting the rear surface side of the solar cell module  2 , and a bolt  8  serving as a fastening member. 
       FIG. 11  is a perspective view of a part of the crosspiece  11  of the attachment stand unit  10 . As shown in  FIG. 11 , the top plate  12  of the crosspiece  11  has an insertion hole  13  through which the bolt  8  is inserted, a T-shaped attachment aid hole  15  for attachment of the placing fitting  4 , and a positioning slit  14 . 
     The insertion hole  13  is a thin, long hole elongated in the left-right direction for fine adjustment the insertion position of the bolt  8 . The positioning slit  14  is for the purpose of inserting a positioning piece  43 , described later, of the placing fitting  4 . The positioning slit  14  is a thin, long hole elongated in the left-right direction for fine adjustment of the insertion position of the positioning piece  43  of the placing fitting  4 . 
       FIG. 12  is a perspective view of the securing fitting  3 . As shown in  FIG. 12 , the securing fitting  3  includes: protrusion pieces  32  that protrude downwardly at both front and rear end portions of a flat-plate shaped pressing plate  31 ; and an insertion hole  33  that penetrates through a center portion of the pressing plate  31 . 
     The pressing plate  31  is used to press, from above, the two solar cell modules  2  adjoiningly disposed on the top plate  12  of the crosspiece  11  of the attachment stand unit  10 . The insertion hole  33  is a hole through which the bolt  8  is inserted. The protrusion pieces  32  of the securing fitting  3  are inserted into the gap between the left and right solar cell modules  2 . 
       FIG. 13  is a perspective view of the placing fitting  4 . As shown in  FIG. 13 , the placing fitting  4  includes an upper plate  40 , a lower plate  50 , and a joint portion  60  that combines the upper plate  40  with the lower plate  50 . A waist portion  61  to facilitate bending is disposed along the joint portion  60 . 
     The lower plate  50  includes: a lower plate rear wall  50   b  that is bent at a rear end edge of the lower plate  50 ; and a lower plate front wall  50   a  that is bent at a front end edge of the lower plate  50 . The lower plate  50  also includes an engagement piece  50   c  that is bent at an end edge of the lower plate front wall  50   a.    
     The upper plate  40  includes engagement slits  41  formed adjacent to both left and right ends of the upper plate  40 . The upper plate  40  also includes, at its rear end edge, the positioning piece  43  that is downwardly bent. The positioning piece  43  includes an engagement groove  43   a.    
     Also, an insertion hole  42  penetrates through a center portion of the upper plate  40 , and a fastening hole  51  is formed in the lower plate  50 . The insertion hole  42  of the upper plate  40  is a hole through which the bolt  8  is inserted, and the fastening hole  51  of the lower plate  50  is a screw hole into which the bolt  8  as a fastening member is screwed. 
     As shown in  FIGS. 14 to 16 , the placing fitting  4  is bent at the waist portion  61  of the joint portion  60 . Then, the upper plate  40  and the lower plate  50  are disposed in a mutually opposing manner with a gap therebetween. The positioning piece  43  of the upper plate  40  is fitted into a long hole  50   d  of the engagement piece  50   c  of the lower plate  50 . A protruding portion  50   e  of the engagement piece  50   c  is fitted into a long hole  43   a  of the positioning piece  43 . Thus, the upper plate  40  and the lower plate  50  are engaged with one another. 
     As shown in  FIG. 17 , with the waist portion  61  of the joint portion  60  bent, the placing fitting  4  is engaged with the T-shaped attachment aid hole  15  and the positioning slit  14  of the upper plate  12  of the crosspiece  11 . 
       FIGS. 18 to 21  illustrate a procedure for attaching the placing fitting  4  to the upper plate  12  of the crosspiece  11  of the attachment stand unit  10 . 
     First, as shown in  FIG. 18 , with both left-right ends of the upper plate  40  of the placing fitting  4  crossing the longitudinal direction of the top plate  12  of the crosspiece  11  at right angles, the lower plate  50  is put into the attachment aid hole  15  of the top plate  12  so as to insert the joint portion  60  of the placing fitting  4  through the attachment aid hole  15 , as shown in  FIG. 19 . 
     Then as shown in  FIG. 20 , the entire placing fitting  4  is rotated at a right angle about the joint portion  60 . The positioning piece  43  of the placing fitting  4  is inserted into the position slit  14  of the top plate  12  of the crosspiece  11 , and the position of the placing fitting  4  in the front-rear direction is determined. 
     Then as shown in  FIG. 21 , the waist portion  61  of the joint portion  60  of the placing fitting  4  is bent by  90  degrees to dispose the lower plate  50  and the upper plate  40  in a mutually opposing manner across the top plate  12 , so that the top plate  12  is held between the lower plate  50  and the upper plate  40 . Thus, the top plate  12  is attached to the placing fitting  4 . In this respect, the positioning piece  43  of the upper plate  40  is inserted into the long hole  50   d  of the engagement piece  50   c  of the lower plate  50 , while the protruding portion  50   e  of the engagement piece  50   c  is inserted into the long hole  43   a  of the positioning piece  43 . Thus, the lower plate  50  and the upper plate  40  are engaged with one another. 
     As shown in  FIGS. 7 to 10 , with the placing fitting  4  attached to the top plate  12  of the crosspiece  11  of the center attachment stand unit  10 , an end portion of the reinforcing bar  21  of the left solar cell module  2  is placed on the upper plate  40  of the placing fitting  4  from the vicinity of the center of the upper plate  40  over the left space thereof A protruding engagement portion  21   b  of the reinforcing bar  21  is fitted with the left engagement slit  41  of the upper plate  40  of the placing fitting  4 . Simultaneously, an end portion of the reinforcing bar  21  of the right solar cell module  2  is mounted on the upper plate  40  of the placing fitting  4  from the vicinity of the center of the upper plate  40  over the right space thereof A protruding engagement portion  21   b  of the placing fitting  4  is fitted with the right engagement slit  41  of the upper plate  40  of the placing fitting  4 . In this manner, the left and right solar cell modules  2  are positioned with a uniform gap therebetween on the upper plate  40  of the placing plate  4 . 
     Thus, the left and right solar cell modules  2  are positioned in a mutually opposing manner with a uniform gap therebetween on the two placing fittings  4 . This ensures that on the center attachment stand unit  10 , two points of the gap between the left and right solar cell modules  2  are uniform, thereby disposing the left and right solar cell modules  2  in parallel to one another. 
     Meanwhile, over the left and right attachment stand units  10 , the reinforcing bar  21  of the left or right solar cell module  2  is mounted on the upper plate  40  of the placing fitting  4 . The protruding engagement portion  21   b  of the reinforcing bar  21  is fitted with the engagement slit  41  of the upper plate  40  of the placing fitting  4 . Thus, the left or right solar cell module  2  is positioned. 
     The positioning of the solar cell module  2  is carried out with the placing fitting  4  not secured. As shown in  FIG. 11 , the T-shaped attachment aid hole  15 , the positioning slit  14 , and the insertion hole  13  of the top plate  12  of the crosspiece  11  are all rectangular shaped to permit left and right movement of the placing fitting  4 . Hence, not securing the placing fitting  4  ensures that the protruding engagement portions  21   b  of the placing fittings  4  of the left and right solar cell modules  2  are fitted with the left and right engagement slits  41  of the upper plates  40  of the placing fittings  4  while at the same time adjusting the position of the placing fittings  4  relative to the left and right solar cell modules  2 . 
     Additionally, the placing fittings  4  are interposed between the solar cell modules  2  and the crosspiece  11 . This provides tolerance for the positions of the solar cell modules  2  in the left and right direction relative to the attachment stand units  10 . This ensures that even if there is a difference in intervals between the attachment stand units  10 , adjusting the positions of the placing fittings  4  relative to the left and right solar cell modules  2  positions the left and right solar cell modules  2  and uniformizes the gap between the left and right solar cell modules  2 . This greatly facilitates the installation work of the solar cell modules  2 . 
     After the solar cell modules  2  are positioned, as shown in  FIGS. 7 to 10 , the securing fitting  3  is placed on the center attachment stand unit  10  at the reinforcing bar  21  part of each solar cell module  2 . The protrusion pieces  32  of the securing fitting  3  are inserted into the gap between the left and right solar cell modules  2 . Each of the protrusion pieces  32  of the securing fitting  3  is held between the hooking portions  21   a  of the left and right reinforcing bars  21 . The bolt  8  is inserted through the insertion hole  33  of the securing fitting  3  and the insertion hole  42  of the upper plate  40 . The bolt  8  is screwed into the fastening hole  51  of the lower plate  50  through the insertion hole  13  of the top plate  12  of the crosspiece  11 , where the bolt  8  is tightly fastened. Thus, the solar cell panels  20  and the reinforcing bars  21  of the left and right solar cell panels  2  are held and supportably secured between the placing fitting  4  and the securing fitting  3 . 
     Meanwhile, on the left and right attachment stand units  10 , the securing fitting  3  is mounted at the reinforcing bar  21  part of the left or right solar cell module  2 . The protrusion pieces  32  of the securing fitting  3  are pressed against the hooking portion  21   a  of the reinforcing bar  21  of the left or right solar cell module  2 . The bolt  8  is inserted into the insertion hole  33  of the securing fitting  3  and the insertion hole  42  of the upper plate  40 . The bolt  8  is screwed into the fastening hole  51  of the lower plate  50  through the insertion hole  13  of the top plate  12 , where the bolt  8  tightly fastened. The solar cell panels  20  and the reinforcing bars  21  of the left or right solar cell module  2  are held and supportably secured between the placing fitting  4  and the securing fitting  3 . 
     Thus, in the solar cell attachment stand  1 , each solar cell panel  20  of the solar cell module  2  is fastened and supported at the reinforcing bar  21  part. This ensures that not all the fastening force acts on the solar cell panel  20  itself, which in turn ensures firm support of the solar cell module  2  without chipping and damage to the solar cell panel  20 . 
     Additionally, the solar cell panel  20  is not directly coupled with the placing fitting  4  of the attachment stand unit  10 ; instead, the protruding engagement portion  21   b  of the reinforcing bar  21  is fitted with the engagement slit  41  of the placing fitting  4 . This makes an external force difficult to directly act on the solar cell panel  20 , thereby preventing chipping and damage to the solar cell panel  10 . 
     Further, not only the solar cell module  2  but also the solar cell attachment stand  1  itself is simple in structure. This reduces the piece-part count and facilitates the installation work. In particular, when a large-scale photovoltaic power generating system is established, the facilitated installation work is a great advantage. 
     Next, a solar cell module according to a second embodiment of the present invention will be described.  FIG. 22  is a perspective view of a solar cell module according to this embodiment.  FIG. 23  is a partially enlarged cross-sectional view of the solar cell module according to this embodiment.  FIG. 24  is a partially enlarged and exploded perspective view of the solar cell module according to this embodiment. 
     As clearly seen from  FIGS. 22 to 24 , a solar cell module  2 A includes a solar cell panel  20  and two reinforcing bars  21 A. The two reinforcing bars  21 A are disposed to laterally cross the solar cell panel  20  and superimposed and adhered on the rear surface of the solar cell panel  20 . 
     The solar cell panel  20  includes a transparent substrate such as of glass on which a thin-film semiconductor layer, an electrode film, and the like are layered. The thin-film semiconductor layer, the electrode film, and the like are covered with a rear surface protective layer and the like. To each of opposing two sides  20   a  of the solar cell panel  20 , an elastic tape  22  is adhered for shock absorption. 
     The reinforcing bar  21 A includes: a rectangular main plate  21   d  having approximately the same length as the lateral width of the solar cell panel  20 ; side plates  21   e  that are bent downwardly (to the rear surface side of the reinforcing bar  21 A) on both sides of the main plate  21   d;  hooking portions  21   a  that are bent upwardly on both ends of the main plate  21   d;  and protruding engagement portions  21   b  formed by downwardly bending U-shaped notch parts formed adjacent to both ends of the main plate  21   d.  The height of each hooking portion  21   a  is lower than the thickness of the solar cell panel  20 . The side plates  21   e  are cut off adjacent to both ends of the main plate  21   d.  An example of the reinforcing bar  21 A is made of a steel plate that is cut, bent, and subjected to plating. 
     An adhesive is applied to the upper surface  21   c  of the main plate  21   d  of the reinforcing bar  21 A. The upper surface  21   c  is superimposed and pressed on the rear surface of the solar cell panel  20 . The opposing two sides  20   a  of the solar cell panel  20  are held between the hooking portions  21   a,  so that the reinforcing bar  21 A is adhered and secured on the rear surface of the solar cell panel  20 . 
     Compared with the reinforcing bar  21  of the solar cell module  2  of  FIGS. 1 to 3 , the reinforcing bar  21 A of the solar cell module  2 A is different from the reinforcing bar  21  in that the reinforcing bar  21 A has the side plates  21   e  while being similar to the reinforcing bar  21  in that the reinforcing bar  21  A has the hooking portions  21   a  and the protruding engagement portions  21   b.  This ensures attachment of the solar cell module  2 A on the top plate  12  of the crosspiece  11  of the attachment stand unit  10 , similarly to the solar cell module  2  of  FIG. 10 . Specifically, as shown in  FIG. 25 , the solar cell module  2 A is attached on the top plate  12  of the crosspiece  11  using a securing fitting  3  abutting the light receiving surface side of the solar cell module  2 A, a placing fitting  4  abutting the rear surface side of the solar cell module  2 A, and a bolt  8  serving as a fastening member. The side plates  21   e  are cut off adjacent to both ends of the main plate  21   d.  The gap between the side plates  21   e  is larger than the width of the upper plate  40  of the placing fitting  4 . This ensures that the side plates  21   e  do not interfere with the crosspiece  11  and the placing fitting  4 . 
     This ensures establishment of a photovoltaic power generating system including a plurality of solar cell modules  2  mounted on the solar cell attachment stand  1 , similarly to the solar cell module  2  of  FIGS. 1 to 3 . 
     The reinforcing bar  21 A has a U-shaped cross-section defined by the main plate  21   d  and the side plates  21   e.  This ensures high bending strength of the reinforcing bar  21 A, which increases the strength of the solar cell module  2 A to which the reinforcing bar  21 A is adhered and secured. Also in the solar cell attachment stand  1 , the reinforcing bar  21 A is secured across the crosspieces  11 , which increases the strength of the solar cell attachment stand  1 . 
     It is noted that the prevent invention is not limited to the above-described embodiments, but can be modified in various forms. For example, the reinforcing bar  21  or  21 A may not be adhered and secured to the rear surface of the solar cell panel  20  in advance; instead, the adhesion of the reinforcing bar  21  or  21 A may be at the time of installation of the solar cell panel  20 . Alternatively, instead of being adhered, the reinforcing bar  21  or  21 A may be merely supportably secured by holding the solar cell panel  20  and the reinforcing bar  21  or  21 A between the securing fitting  3  and the placing fitting  4 . 
     It is also possible to increase the number of the reinforcing bars  21  and  21 A, or superimpose the reinforcing bars  21  and  21  on each other in a crosswise manner on the rear surface of the solar cell panel  20 . 
     It is also possible to use engagement portions of other structures or shapes to replace the protruding engagement portion  21   b  of the reinforcing bars  21  and  21 A and the engagement slit  41  of the upper plate  40  of the placing fitting  4 . 
     The solar cell panel is not limited to the above-described example, wherein a thin-film semiconductor layer, an electrode film, and the like are layered on a transparent substrate such as of glass, with a rear surface protective layer and the like covering and protecting the thin-film semiconductor layer, the electrode film, and the like. It is also possible to employ solar cell panels of other types, such as one using a substrate of single crystal silicon or polycrystalline silicon. 
     DESCRIPTION OF THE REFERENCE NUMERAL 
     
         
           1  Solar cell attachment stand 
           2 ,  2 A Solar cell module 
           3  Securing fitting 
           4  Placing fitting 
           8  Bolt 
           10  Attachment stand unit 
           11  Crosspiece 
           12  Top plate 
           16  Support 
           17  Front bracket 
           18  Rear bracket 
           20  Solar cell panel 
           21 ,  21 A Reinforcing bar