Abstract:
[Problem] To provide a solar power system and a solar panel installation method with which, by using a positioning configuration which is not prone to visible vertical misalignment while preserving sunlight lighting efficiency in the positioning of a plurality of solar panels, solar panel installation is easy, and which is suitable to installing a large solar power system on a hill, in wetlands, etc. [Solution] A solar power system comprises a solar panel group ( 2 ) in which a plurality of vertically oriented rectangular solar panels ( 21 ) are inclined in the same direction, either left or right, at a prescribed angle of inclination (theta), and the lighting faces ( 22 ) of each of the solar panels ( 21 ) are arrayed in the same plane.

Description:
TECHNICAL FIELD 
     The present invention relates to an installation method of a solar power system having a plurality of solar panels, and a solar panel. 
     BACKGROUND ART 
     Conventionally, a plurality of solar panels used in a solar power system are installed by being arranged in an orderly manner without providing level-differences or clearances in vertical and horizontal directions. 
     For example, there proposed a solar panel mounting method in Japanese Patent Laid-Open No. 2010-209515 in which rectangular solar panels are arranged on top of a frame provided on the roof of a building without providing level-differences or clearances (Patent Literature 1). It is necessary to make the size compact by removing level-differences or clearances since the area on the roof is limited, and in consideration of appearance, a solar panel group arranged in an orderly manner without providing level-differences or clearances features a beautiful appearance to see since the panel group is installed at a conspicuous location on the roof. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent Laid-Open No. 2010-209515 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     However, the invention described in Patent Literature 1 requires a large amount of cost and labor because high construction accuracy from frame installation to mounting work must be secured in order to keep the beauty of appearance. In particular, in a plurality of solar panels arranged in an orderly manner, when a level-difference is caused by a vertical misalignment between each of adjacent solar panels, and a level-difference is caused in the inclined face by a misalignment between each of solar panels in the front-back direction, these level-differences become conspicuous and give an impression of an unattractive appearance. 
     Furthermore, demands for electric power generation using clean energy are increasing in recent years and a large-scale solar power system is planned. Therefore, it is thought that an installation location for the solar power system should not be limited to a comparatively stable location such as on a roof, but unused lands such as a hilly area or a wet area should be utilized. 
     However, when the solar power system is installed on a hilly area or a wet area, it is extremely difficult to construct the frame horizontally in the conventional way. That is, when a conventional system is adopted, the hilly area must be leveled first in order to install the solar panels horizontally on the hilly area, which wastes a great cost and time. When installing on a soft ground such as a wet area, the frame is possible to incline due to a subsidence of the foundation etc. even if constructed with high accuracy. 
     Additionally, when the plurality of solar panels that configure the solar panel group is partly out of order or damaged, it should be sufficient to exchange only some part of the panels, but the size slightly differs since a standard on size is not necessarily unified in all the manufacturers, and it is possible that the standard may be changed even in the same manufacturer. In such a case, all of the solar panels must be exchanged in order not to generate a level-difference or a clearance between the solar panels. 
     The present invention is provided to solve such problems. It is an object of the present invention to facilitate solar panel installation by using an arrangement configuration in which it is hard to recognize level-differences in the vertical direction and level-differences of the inclined face, a difference in an inclination angle of each of the solar panels either inclined left or right, and a difference in a clearance between each of the solar panels, while maintaining lighting efficiency of the sunlight in an arrangement of the plurality of solar panels, and to provide a suitable method for installing the solar power system and the solar panels in a case when an upsizing solar system is installed on a hilly area, a wet area, or the like. 
     Solution to Problem 
     A solar power system according to the present invention includes a solar panel group in which a plurality of vertically oriented rectangular solar panels are inclined in the same direction either left or right at a predetermined inclination angle, and a lighting face of each of the solar panels is arranged in a same plane. 
     Furthermore, as an aspect of the present invention, the inclination angle of each of the solar panels that configure the solar panel group may be between 15 degrees and 45 degrees. 
     Additionally, as an aspect of the present invention, a clearance equal to or smaller than the width of the solar panel may be provided between each of the solar panels that configure the solar panel group. 
     In the installation method of the solar panel according to the present invention, a plurality of vertically oriented rectangular solar panels are inclined in the same direction either left or right at a predetermined inclination angle, and the lighting face of each of the solar panels are arranged in the same plane. 
     Furthermore, as an aspect of the present invention, the inclination angle of each of the solar panels may be set to between 15 degrees and 45 degrees. 
     Additionally, as an aspect of the present invention, the solar panels may be arranged so that a clearance equal to or smaller than the width of the solar panel is provided between each of the solar panels. 
     Advantageous Effect of Invention 
     According to the present invention, it is possible to facilitate solar panel installation and to install an upsizing solar system on a hilly area, a wet area, or the like by using arrangement configuration in which it is hard to recognize level-differences in a vertical direction and level-differences of an inclined face, a difference in an inclination angle of each of the solar panels in either cases of inclined to left or right, and a difference in a clearance between each of solar panels, while maintaining lighting efficiency of the sunlight in an arrangement of the plurality of solar panels. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing an embodiment of a solar power system according to the present invention. 
         FIG. 2  is an overall perspective view showing a solar panel group according to the embodiment. 
         FIG. 3  is a partially enlarged perspective view showing a solar panel group according to the embodiment. 
         FIG. 4A  is a view showing a difference in angles between a solar panel and a perpendicular line in cases facing to the front and facing to the lighting face,  FIG. 4B  and is a side view of  FIG. 4A  according to the embodiment. 
         FIG. 5  is an overall perspective view showing a solar panel group according to another embodiment, the group including 20 or more solar panels arranged in a single row. 
         FIG. 6  is a view showing visual relations between level-differences and inclination angles of the solar panel group according to the example 1. 
         FIG. 6A  is an enlarged view of circle  6 A in  FIG. 6 , illustrating a level-difference G formed by adjacent two panels in a height direction. 
         FIG. 7  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 0 degrees. 
         FIG. 8  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 5 degrees. 
         FIG. 9  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 10 degrees. 
         FIG. 10  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar power group according to the example 2 is 15 degrees. 
         FIG. 11  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 20 degrees. 
         FIG. 12  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 25 degrees. 
         FIG. 13  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 30 degrees. 
         FIG. 14  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 35 degrees. 
         FIG. 15  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 40 degrees. 
         FIG. 16  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 45 degrees. 
         FIG. 17  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 50 degrees. 
         FIG. 18  is a view showing visual relations between level-differences and clearances when the inclination angles of the solar panel group according to the example 2 is 55 degrees. 
         FIG. 19  is a view showing visual relations between level-differences and clearances, when the inclined direction of the solar panel group according to the example 3 is left and inclined angle thereof is 30 degrees. 
         FIG. 20  is a view showing relations between inclination angles and clearances in cases of one stage and two stages in a vertical direction of the solar panel group according to the example 4. 
         FIG. 21  is a view showing relations between inclination angles and clearances in cases of two stages and three stages in a vertical direction of the solar panel group according to the example 4. 
         FIG. 22  is a view showing relations between inclination angles and clearances in cases of three stages and four stages in a vertical direction of the solar panel group according to the example 4. 
         FIG. 23  is a front view showing designed solar panels and frames according to the example 5. 
         FIG. 24  is a front view showing coordinate values for the four corners and inclination angles of constructed solar panels according to the example 5. 
         FIG. 25  is a digital photo image of the constructed solar panels according to the example 5 shot from the front left. 
         FIG. 26  is a digital photo image of the constructed solar panels according to the example 5 shot from the front right. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes an embodiment of an installation method of a solar power system and a solar panel according to the present invention with reference to the drawings.  FIG. 1  is a block diagram showing each configuration of a solar power system  1  according to the embodiment.  FIG. 2  is an overall perspective view showing a solar panel group  2 A according to the embodiment and  FIG. 3  is a partially enlarged perspective view of  FIG. 2 . 
     The solar power system  1 , as shown in  FIGS. 1 to 3 , generally includes a plurality of solar panels  21 ,  21  . . . , a frame  3  for installing each of solar panels  21 ,  21  . . . and a current collector  4  that collects a DC current generated by each of the solar panels  21 ,  21  . . . and transmits to a power network  5  etc. The following describes each configuration in detail. 
     The solar panel  21  is a solar panel generally available on the market. As shown in  FIGS. 2 and 3 , the top side of the solar panel  21  is a lighting face  22  which serves to receive the sunlight and the DC current is generated by receiving the sunlight on the lighting face  22 . 
     The solar panel  21  according to the embodiment is formed in a vertically oriented rectangular shape and an aspect ratio thereof is approximately 1.5:1. The solar panels  21  are unitized by arranging consecutive three sheets in a horizontal direction, and formed in a vertically oriented rectangular shape with an aspect ratio approximately 4.5:1. In the embodiment, as shown in  FIGS. 2 and 3 , the solar panel group  2 A is configured by arranging and installing the large number of solar panels  21 ,  21  . . . formed in a vertically oriented rectangular shape in the horizontal direction. Expansion of the solar panel group  2 A to the horizontal direction is limited by arranging and unitizing the solar panels  21  in the vertical direction, which allows securing adequate amount of power generation. 
     Note that a size and an aspect ratio of the solar panel  21  are not particularly to be limited and should be selected as appropriate. The solar panel group  2 A may not only be configured by three-sheet solar panels  21  but also be configured by arranging one-sheet vertically oriented rectangular solar panel  21  in the horizontal direction if adequate amount of power generation can be secured. In addition, the number of the solar panels  21  arranged in the vertical direction should be determined as appropriate in consideration of desired amount of power generation, a wind force received on the solar panel  21 , an amount of snow accumulated on the solar panel  21  etc., which means two sheets is acceptable and four sheets or more is also acceptable. 
     Next, each solar panels  21 ,  21  . . . that configures the solar panel group  2 A is installed to the frame  3  using the following installation method in order to be visually hard to recognize by making inconspicuous the level-differences in the vertical direction and level-differences of the inclined face occurring between arranged solar panels  21 , a difference in an inclination angle θ of each of the solar panels in a case when inclined either left or right, and a difference in clearance O between each of the solar panels. 
     First, each of solar panels  21 ,  21  . . . is installed inclining at the predetermined inclination angle θ in the same direction either left or right. Note that the solar panel  21  is, as shown in  FIGS. 2 and 3 , installed on a hereinafter described inclination portion  34  of the frame  3 . Therefore, apparent angles of the solar panel  21  differ from the angle to be seen from. For example, as shown  FIGS. 4A and 4B , when the solar panel  21  with an aspect ratio approximately 5:1 is mounted on the inclination portion  34  inclined at 30 degrees (or light facing angle), the angle θ between the solar panel  21  and a perpendicular line PL is approximately 19.4 degrees in a case facing to the front of the solar panel  21 , while the angle θf is approximately 10 degrees in a case facing to the lighting face  22  of the solar panel  21 . Therefore, in the present invention, the inclination angle θ is defined as an angle created by the solar panel  21  and the perpendicular line in a case facing to the front of the solar panel group  2 , in consideration of the actual condition in which the solar panel group  2  is viewed. Each of the solar panels  21 ,  21  . . . according to the embodiment is, as shown in  FIGS. 2 and 3 , installed inclining rightward.  FIG. 4B , the inclination portion  34  is further illustrated. The inclination portion  34  functions as a light facing plane which is designed to be set to face the sun when the frame is installed on the ground. The light facing plane is an imaginary plane that can be determined by at least two parts of the frame  3 . In the embodiment, one part is a tip portion  32   ft  of front frame body  32   f , which is a lower and front side of the frame. The other part is a tip portion  34   bt  of back frame body  32   b , which is an upper and back side of the frame. The light facing angle of the light facing plane, which is defined with respect to a depth direction (Y), is denoted with reference α, As shown in  FIGS. 4A and 4B , the depth direction (Y) means a horizontal direction from the front to the back of the frame, the width direction (X) means another horizontal direction from the right to let (or lateral) of the frame, the height direction (Z) means a perpendicular direction to the horizontal direction. In the invention, the tem, “horizontal,” may be defined as parallel to the ground below the panels, or may be determined by a direction which is perpendicular to the gravity direction. The height direction can be defined according to the definition of the horizontal direction. 
     As to the inclination angle θ of each of the solar panels  21 ,  21  . . . , as the angle of inclination increases, it gets visually harder to recognize level-differences in the vertical direction and level-differences of the inclined face occurring between the solar panels  21 , and a difference in the inclination angle θ and a difference in the clearance O. On the other hand, as the angle of inclination increases, because the solar panel  21  is formed in a vertically oriented rectangular shape, the width of the solar panel group  2 A expands, which requires a larger installation location. Therefore, in consideration of a balance between a visual effect of being hard to recognize a level-difference, and the installation location, the inclination angle θ between 15 degrees and 45 degrees is preferred, that between 20 degrees and 40 degrees is more preferred, and that of approximately 30 degrees is even more preferred. 
     Furthermore, each of the solar panels  21  of the solar panel group  2 A is arranged with the lighting faces  22  arranged in the same plane so that adjacent solar panels  21  may not overlap and make a shadow on another solar panel  21 . It is done in order to maintain the lighting efficiency in each of solar panels  21 ,  21  . . . . Note that the same plane where each of the solar panels  21 ,  21  . . . are arranged may be a linear plane shape as shown in the embodiment and also may be a curved plane shape as shown in  FIG. 5 . 
     Additionally, each of the solar panels  21 ,  21  . . . is arranged by providing a clearance O which is equal to or smaller than a width W of the solar panel  21  between every panel. As the clearance O increases, it becomes visually harder to recognize level-differences in the vertical direction and level-differences of the inclined face, and difference in the inclination angle θ and the difference in the clearance O occurring between the solar panels  21 . Therefore, the clearance O according to the embodiment serves to increase a visual effect of being hard to recognize the level-differences and the differences in the inclination angle θ etc. caused by inclining the solar panels  21 . On the other hand, a larger width of the clearance O requires a larger installation location because the width of the solar panel group  2 A expands. Therefore, in consideration of a balance between a visual effect of being hard to recognize the level-differences and the differences in the inclination angle θ etc., and the installation location, it is preferred that the clearance O is equal to or smaller than the width W of the solar panel  21 . 
     Next, the frame  3  according to the embodiment is described. 
     The frame  3  is a stand for inclining the plurality of solar panels  21 ,  21  . . . at the predetermined inclination angle θ using the above-mentioned installation method, arranging the lighting faces  22  of each of the solar panels  21 ,  21  . . . in the same plane, and arranging the panels by providing the clearance O. The frame  3  according to the embodiment, as shown in  FIGS. 2 and 3 , includes a base portion  31  buried at the installation location, a frame body  32  installed on the base portion  31 , and a panel installation rail  33  for installing each of solar panels  21 ,  21  . . . , by forming the same plane on the frame body  32 . 
     The base portion  31  is buried in the installation location and serves to support the frame body  32  etc. Note that the construction method and configuration for the base portion  31  are chosen as appropriate in consideration of a status of a foundation of the installation location etc., and a simple foundation construction method etc. using such as spherical foundation which is installable in a concrete foundation or a soft ground can be used. 
     The frame body  32  serves to support the solar panels  21  and is formed of a frame structure in order to secure the strength to support the solar panel  21  and to reduce a force caused by a wind and a weight of accumulated snow. Additionally, the frame body  32  includes the inclination portion  34  that forms an inclination face by inclining a top of the solar panel  21  backward at an angle based on latitude of the installation location in order to increase the lighting effect of the solar panel  21 . 
     The panel installation rail  33  is fixed on the inclination portion  34  of the frame body  32 , and serves to install each of solar panels  21 ,  21  . . . in the same plane. In the embodiment, as shown in  FIGS. 2 and 3 , the frame is configured of three rails that are placed vertically side by side in order to install each of the solar panels  21 ,  21  . . . in a stable manner. 
     Note that the frame  3  may not be limited to the above configuration but also may be installed one by one with solar panel  21 . 
     The current collector  4  serves to collect the DC current generated by each of the solar panels  21 ,  21  . . . and transmit to the power network  5  etc. The embodiment, as shown in  FIG. 1 , includes a junction box  41  for collecting the generated DC current, and a power conditioner  42  which converts the DC current collected by the junction box  41  to an AC current and performs a system interconnection to power networks such as commercial electrical distribution system. 
     Note that the DC current generated by each of the solar panels  21 ,  21  . . . may be stored in a storage battery or may be supplied directly to an electric appliance. Additionally, although not illustrated, it is also allowed to transmit electricity to a plurality of systems, electric appliances etc. in parallel or by switching to each by providing a distribution board. 
     Next, effects given by the inclination angle θ and the clearance O of the solar panel group  2 A according to the solar power system  1  of the embodiment are described in detail. 
     A general effect given by installing the solar panel group  2 A at an inclination angle θ is, as mentioned above, to make visually inconspicuous and hard to recognize level-differences in the vertical direction and level-differences of the inclined face, differences in the inclination angle θ and differences in the clearance O that cause in each of the solar panels  21 ,  21  . . . . Therefore, when the solar panel  21  is installed on the frame  3 , especially high levels of construction accuracy in the vertical direction and in the inclined face and for the inclination angle θ etc. are not required, which facilitates the construction. Additionally, even if solar panels  21  slightly different in size are used, the differences in size among the solar panels  21  are inconspicuous. 
     A general effect given by installing the solar panels  21  by providing the clearances O therebetween is, similar to the effect of providing the inclination angle θ, to make it hard to recognize level-differences in the vertical direction and level-differences of the inclined face, differences in the inclination angle θ and differences in the clearance O occurring between the solar panels  21 . Therefore, the clearance O in the embodiment can increase more the visual effect of being hard to recognize level-differences in the vertical direction and level-differences of the inclined face, the differences in the inclination angle θ and the differences in the clearance O by providing the inclination angle θ. Furthermore, it is possible to prevent a dangerous damage or collapse by a wind force by providing the clearance O between each of the solar panels  21 ,  21  . . . , since the wind can escape through the clearance O. Moreover, the clearance O prevents snow from accumulating easily on the lighting face  22  of the solar panel  21 . 
     Additionally, the solar panels  21  match the scenery and look visually beautiful by arranging in the same plane, as shown in  FIGS. 2 and 5 . 
     The following describes effects of each configuration during generating electricity according to the solar power system  1  of the embodiment. 
     The solar panel group  2 A according to the embodiment generates a DC current by receiving sunlight on the lighting faces  22 . The DC current generated by each of the solar panels  21 ,  21  . . . is collected to the junction box  41  in the current collector  4  and transmitted to the power conditioner  42 . In the power conditioner  42 , the DC current generated by each of the solar panels  21 ,  21  . . . is then converted to an AC current and transmitted to the power network  5 . 
     Here, the solar panel  21  according to the embodiment has no chance to make a shadow by overlapping between the solar panels  21  because the panels are arranged in the same plane, which can maintain the lighting efficiency of the sunlight. 
     In addition, in the embodiment, since a large amount of lighting area with a predetermined width can be secured by configuring the solar panel  21  in a vertically oriented rectangular shape, expansion of the installation location in the horizontal direction caused by the provided clearance O may be limited and sufficient amount of power generation may be secured. 
     The above method for installing the solar power system  1  and the solar panel  21  according to the embodiment may obtain the following effects. 
     1. Since a level-difference in the vertical direction and a level-difference of the inclined face, a difference in an inclination angle θ, and a difference in a clearance O between adjacent solar panels  21  are made to be inconspicuous, even if positions between each of the solar panels  21  are misaligned to some extent, both functional and apparent problems may not occur and it may become easy to align the base portion  31  and the frame body  32 . That is, since construction accuracy has a margin, the construction can be performed simply and quickly.
 
2. Even if a level-difference or a difference in the inclination angle θ etc. is caused by such as a ground subsidence after construction, they are apparently inconspicuous and the solar panel can match the scenery and can visually maintain the beauty.
 
3. When a part of the solar panel group  2 A is replaced to a solar panel  21  slightly different in size, it is inconspicuous and hard to recognize even if there is a level-difference.
 
4. Since each of the solar panels  21 ,  21  . . . is arranged in the same plane, the lighting efficiency of the sunlight can be maintained.
 
5. Amount of power generation can be secured by forming the solar panel  21  in a vertically oriented rectangular shape without making a vertical misalignment conspicuous.
 
     Next, studies were performed regarding effects that the installation method of the solar power system  1  and the solar panel  21  according to the present invention makes a level-difference of the solar panels  21  visually inconspicuous, which are described in each of the following examples. 
     Example 1 
     In an example 1, a study was performed regarding a visual relation between a level-difference G, which is more apparently illustrated in  FIG. 6A , and an inclination angle θ caused in a solar panel group  2 . In the example 1, a set of solar panels  21  formed of three sheets of solar panels  21  with 1 W in width and 1.5 W in height in the vertical direction were arranged in the horizontal direction without a clearance, which formed the solar panel group  2 . Furthermore, a level-difference of 0.2 W in height, relative to the width W, was provided to a solar panel  21  located at a nearly center in the horizontal direction. Additionally, each of the solar panels  21 ,  21  . . . was inclined rightward with an inclination angle θ increased from 0 degrees to 55 degrees in increments of 5 degrees. 
       FIG. 6  illustrates each of arranged solar panel group  2  indicating results according to the example 1. In  FIG. 6 , (a) denotes a case that inclination angle θ=0 degrees, (b) denotes a case that inclination angle θ=5 degrees, (c) denotes a case that inclination angle θ=10 degrees, (d) denotes a case that inclination angle θ=15 degrees, (e) denotes a case that inclination angle θ=20 degrees, (f) denotes a case that inclination angle θ=25 degrees, (g) denotes a case that inclination angle θ=30 degrees, (h) denotes a case that inclination angle θ=35 degrees, (i) denotes a case that inclination angle θ=40 degrees, (j) denotes a case that inclination angle θ=45 degrees, (k) denotes a case that inclination angle θ=50 degrees, and (l) denotes a case that inclination angle θ=55 degrees. 
     As shown in  FIG. 6 , as the inclination angle θ got larger, the level-difference became visually more inconspicuous and harder to recognize. In particular, as shown in (d) to (l) in the figure, when the inclination angle θ was equal to or larger than 15 degrees, it was hard to recognize the level-difference unless trying to find it consciously, and as shown in (g) to (l) in the figure, when the inclination angle θ was equal to or larger than 30 degrees, it was almost impossible to recognize even if seen consciously. 
     Accordingly, it was understood that when the inclination angle θ of the solar panels  21  that configure the solar panel group  2  was equal to or larger than 15 degrees, it was hard to recognize the level-difference, and when the inclination angle θ was equal to or larger than 30 degrees, it was almost impossible to recognize. 
     Example 2 
     In an example 2, a study was performed regarding a visual relation between a level-difference caused in a solar panel group  2  and a value of a clearance O between solar panels  21 . The solar panel  21  of the example 2 was same as the solar panel  21  of the above example 1 and the solar panel group  2  was formed of the solar panels  21  with aspect ratio 4.5:1 arranged in the horizontal direction. Furthermore, a level-difference of 0.2 W in height, relative to the width W of the solar panel  21 , was provided to a nearly center of the solar panel group  2  in the horizontal direction. Additionally, clearances O between 0 W and 0.7 W in increments of 0.1 W, relative to the width W, were provided between each of the solar panels  21 ,  21  . . . that configures the solar panel group  2 . 
       FIGS. 7 to 18  illustrate each of the arranged solar panel groups  2  indicating results according to the example 2.  FIG. 7  illustrates a result in a case that an inclination angle θ is 0 degrees, each item describes as follows, (a) denotes a case that the clearance O=0 W, (b) denotes a case that the clearance O=0.1 W, (c) denotes a case that the clearance O=0.2 W, (d) denotes a case that the clearance O=0.3 W, (e) denotes a case that the clearance O=0.4 W, (f) denotes a case that the clearance O=0.5 W, (g) denotes a case that the clearance O=0.6 W, and (h) denotes a case that the clearance O=0.7 W. 
     As shown in  FIG. 7 , it was understood that as the clearance O between each of the solar panels  21 ,  21  . . . got larger, it became harder to recognize a level-difference even in the case that the inclination angle θ was 0 degrees. 
     Furthermore,  FIGS. 8 to 18  illustrate cases that the inclination angle θ was between 5 degrees and 55 degrees rightward and (a) to (h), similarly to  FIG. 7 , indicate cases that the clearances O between the solar panels  21  are between 0 W and 0.7 W respectively. 
     As shown in  FIGS. 8 to 18 , it was understood that as the clearance O got larger, the level-difference became more inconspicuous and harder to recognize in the case that the inclination angles θ were between 5 degrees and 55 degrees rightward as well. For example, as shown in  FIG. 12 , in the case that the inclination angle θ was 25 degrees, when the clearance O was 0 W, it was possible to recognize a level-difference by seeing consciously, but when the clearance O was 0.7 W, it was almost impossible to recognize the level-difference even by seeing consciously. 
     Accordingly, it was understood that a larger clearance O between the solar panels  21  enabled a level-difference to be inconspicuous, and providing an inclination angle θ made it possible to increase a visual effect that a level-difference in the vertical direction became hard to be recognized. 
     Example 3 
     In an example 3, a study was performed regarding a visual relation on an inclined direction of a solar panel  21 . As shown in  FIG. 19 , the solar panel  21  of the example 3 was same as the solar panel  21  of the above examples 1 and 2, and a solar panel group  2  was formed of the solar panels  21  with aspect ratio 4.5:1 arranged in the horizontal direction. Furthermore, a level-difference of 0.2 W in height, relative to the width W of the solar panel  21 , was provided to a nearly center of the solar panel group  2  in the horizontal direction. Furthermore, clearances O between 0 W and 0.7 W in increments of 0.1 W, relative to the width W of the solar panel  21 , were included between each of the solar panels  21 ,  21  . . . . Note that unlike in the above-mentioned examples 1 and 2, the inclined direction was regarded as leftward. In this case, the inclination angle θ was 30 degrees. 
     When  FIGS. 19 and 13  with an inclination angle θ 30 degrees and a different inclined direction left or right, were compared, it was understood that even if the inclined direction was different, there was no significant change in a visual effect and the level-difference was inconspicuous in either direction inclined to left or right. As well, providing a clearance O enabled the level-difference to be more inconspicuous. 
     Accordingly, it was understood from the example 3 that the level-difference was inconspicuous in either direction of the solar panel  21  inclined to left or right. 
     Example 4 
     In an example 4, a study was performed regarding an influence that a relation between an inclination angle θ and a clearance O of a solar panel group  2  gave to amount of power generation and horizontal overall installation width. In  FIG. 20 , (a) denotes a case that 30 sheets of solar panels  21  were horizontally arranged in vertically one row without a clearance, and (b) to (i) denote cases that 15 sets of solar panels  21  were horizontally arranged in vertically two rows. Therefore, (a) to (i) each had the same number of the solar panels  21  and the theoretically same amount of power generation. 
     Furthermore, in the example 4, all of  FIGS. 20( a ) to ( i )  had a same distance L between the bottom-left corner of the leftmost solar panel  21  and the bottom-right corner of the rightmost solar panel  21 . In  FIGS. 20( b ) to ( i ) , the solar panels  21  were inclined with an inclination angle θ between 10 degrees and 45 degrees in increments of 5 degrees. 
     That is, in the solar panel groups  2  in  FIGS. 20( a ) to ( i )  according to the example 4, amount of power generation and the overall installation width were intended to be constant each. 
     As shown in  FIG. 20( c ) , the clearance O between the solar panels  21  in a case that the inclination angle θ was 15 degrees resulted in 1.0 W relative to the width W of the solar panel  21 . Therefore, it was understood that even if the clearance O was provided between each the solar panels  21 ,  21  . . . , a same number of the solar panels  21  was able to be arranged by increasing the number of the rows in the vertical direction of the solar panels  21  by one row and making the width of the clearance O to be equal to or smaller than 1.0 W. Furthermore, as shown in  FIGS. 20( b ) to ( i ) , it was also understood that as the inclination angle θ of each of the solar panels  21 ,  21  . . . got larger, the clearance O became smaller. 
     In  FIG. 21 , (a) denotes a condition that 30 sets of solar panels  21  were horizontally arranged in vertically two rows without a clearance, and (b) to (i) denote conditions that 20 sets of solar panels  21  were horizontally arranged in vertically three rows with a constant distance of clearance O. 
     In  FIG. 21( b ) , the clearance O between the solar panels  21  in a case that the inclination angle θ was 10 degrees was 0.5 W relative to the width W of the solar panel  21 . It was understood that when a same number of the solar panels  21  were intend to be arranged with respect to the width of a predetermined installation location, changing the number of the rows from two to three might require a smaller clearance O than changing from one to two. 
     Furthermore, as shown in  FIGS. 21( b ) to ( i ) , as the inclination angle θ of each of the solar panels  21 ,  21  . . . got larger, the clearance O became smaller. In particular, in  FIG. 21( i ) , the clearance O between the solar panels  21  in a case that the inclination angle θ was 45 degrees resulted in 0.06 W relative to the width W of the solar panel  21 , and in a case of equal to or larger than 50 degrees, the solar panels  21  resulted in overlapping each other. 
     In  FIG. 22 , (a) denotes a condition that 30 sets of solar panels  21  were horizontally arranged in vertically three rows without a clearance, and (b) to (g) denote conditions that 23 sets of solar panels  21  were horizontally arranged in vertically four rows with a constant distance of clearance O. 
     In this case, as shown in  FIG. 22( g ) , the clearance O between the solar panels  21  in a case that the inclination angle θ was 35 degrees resulted in 0.07 W relative to the width W of the solar panel  21 , and in a case of the inclination angle θ equal to or larger than 40 degrees, the solar panels  21  resulted in overlapping each other. 
     Accordingly, it was understood that the clearance O between each of the solar panels  21  was able to be formed as maintaining amount of power generation by making the clearance O to be equal to or smaller than 1.0 W relative to the width W of the solar panel  21 . Therefore, it indicates that the installation location did not have to be expanded more than necessary by making the clearance O to be equal to or smaller than 1.0 W. It was also understood that the clearance O between each of the solar panels  21  was able to be formed on the predetermined installation location by making the inclination angle θ to be equal to or smaller than 45 degrees. 
     Example 5 
     In an example 5, solar panels  21  were actually arranged on a frame that was installed using a simple foundation construction method, and a study was performed regarding level-differences in a vertical direction and level-differences of the inclined face, differences in an inclination angle θ and differences in a clearance O with respect to construction accuracy were how far recognized. 
     First, design dimensions etc. for the frame  3  and the solar panel  21  used in the example 5 are described. 
     As shown in  FIG. 23 , a base portion  31  according to the example 5, which was a foundation based on a simple foundation construction method using a spherical foundation formed of metal etc., was installed on a horizontally leveled ground and fixed with a plurality of pipe-shaped stakes. 
     A frame body  32  was formed of a frame structure by a plurality of pipes. Each pipe was connected by welding or bolting. 
     Panel installation rails  33  were configured of two rails arranged vertically side by side. An inclination angle of an inclination portion  34  formed by the panel installation rails  33  was 35 degrees. 
     As shown in  FIG. 23 , the solar panels  21  according to the example 5 were unitized by arranging consecutive three sheets in a vertical direction and by fixing the back side of a panel with a shaft made of a square pillar. The unitized solar panel  21  has dimensions of 4496 mm in height and 992 mm in width, and approximately 4.5:1 in aspect ratio. 
     The solar panels  21  were installed by arranging eight sheets in a horizontal direction so that the heights of the panels became equal with respect to the plane formed of the panel installation rails  33 . The clearance O between each of the solar panels  21  was 151 mm and was equal to or smaller than the width W of the solar panel  21 . Furthermore, each of the solar panels  21  is inclined leftward and the inclination angle θ was 43.4 degrees. 
     Next, level-differences and differences in an inclination angle θ in a case that the frame  3  and the solar panel  21  designed as above were constructed on a leveled piled soil. 
     In the example 5, as shown in  FIG. 24 , it was performed to measure how long in distance mm four corners of each of the solar panels  21  misaligned with respect to the designed locations when a reference point was set to the bottom-left corner of the solar panel  21  installed at leftmost position. 
     First, the solar panel  21  installed at leftmost position is described. As shown in  FIG. 24 , X-coordinate values of the bottom-left and bottom-right corners of the relevant solar panel  21  were both 0 mm, which were not misaligned with respect to the designed locations. On the other hand, X-coordinate values of the top-left and top-right corners were both −4 mm, which were misaligned with respect to the designed locations by 4 mm leftward. 
     Furthermore, Z-coordinate value of the bottom-right corner was 14 mm, which was misaligned with respect to the designed location by 14 mm upward. Furthermore, Z-coordinate value of the top-right corner was 21 mm, which was misaligned with respect to the designed location by 21 mm upward. On the other hand, Z-coordinate value of the top-left corner was −7 mm, which was misaligned with respect to the designed location by 7 mm downward. 
     That is, the solar panel  21  installed at leftmost position was inclined to a direction of rotating counterclockwise on a center of the Y-axis around the bottom-left corner with respect to the designed location. 
     Furthermore, Y-coordinate value of the bottom-right corner was −12 mm, which was misaligned with respect to the designed location by 12 mm to the near side. Furthermore, Y-coordinate value of the top-right corner was −20 mm, which was misaligned with respect to the designed location by 20 mm to the near side. Meanwhile, Y-coordinate value of the top-left corner was 4 mm, which was misaligned with respect to the designed location by 4 mm to the far side. 
     That is, the relevant solar panel  21  was inclined to a direction of rotating counterclockwise on a center of the Z-axis and rotating clockwise on a center of the X-axis around the bottom-left corner with respect to the designed location. 
     Moreover, inclination angles θ were calculated based on each coordinate value of the four corners of the solar panels  21 . As shown in  FIG. 24 , the inclination angle θ created by the bottom-right corner and the top-right corner is 43.3 degrees, which was 0.1 degree smaller than the designed value 43.4 degrees for the inclination angle θ. 
     Therefore, it was understood that level-differences in left, right and vertical directions and level-differences in the inclined face and differences in the inclination angles θ compared with designed dimensions etc. were caused in the solar panel  21  according to the example 5. Furthermore, such level-differences and differences are not same on each of the solar panels  21 , which resulted in that each of the solar panels  21  was installed in a distorted status. 
     Furthermore, the fourth and fifth panels from the left out of all the solar panels  21  included the largest relative level-difference and the largest difference in the inclination angle θ. 
     To put it concretely, as shown in  FIG. 24 , Z-coordinate value of the top-right corner of the fourth solar panel  21  from the left was 27 mm, which indicated that this panel was misaligned by 27 mm upward, while Z-coordinate value of the top-right corner of the fifth solar panel  21  from the left was −1 mm, which indicated that this panel was misaligned by 1 mm downward. That is, the level-difference between the fourth and the fifth solar panels  21  from the left was 28 mm. 
     Furthermore, the inclination angle θ of the fourth solar panel  21  from the left was 43 degrees, while that of the fifth solar panel  21  from the left was 43.6 degrees. Therefore, the difference of the inclination angle θ between each of the solar panels  21  was 0.6 degrees. 
     Next, a study was performed regarding a digital photo image of the solar panels  21  actually constructed in the example 5. As a result, as shown in  FIGS. 25 and 26 , a level-difference in the vertical direction and a level-difference of the inclined face, and a difference in the inclination angle θ were almost impossible to recognize visually. In particular, it was possible to be visually recognized in a way that even the fourth and fifth solar panels  21  from the left with the relatively largest level-difference and inclination angle θ were arranged in an orderly manner. In addition, differences in the inclination angles θ of each of the solar panels  21  and the clearances O between the solar panels  21  were also not constant, but such differences were almost impossible to recognize visually. 
     Accordingly, in the solar panel  21  according to the example 5, not only level-differences in the vertical direction and level-differences of the inclined face but also differences of the inclination angles θ and the clearances O between the solar panels  21  were actually almost impossible to recognize visually even if there were such differences. Rather than above, as shown in  FIGS. 25 and 26 , each of the solar panels  21  can be seen arranged regularly with an unprecedented functional beauty and can be said to be arranged in a beautiful order at sight. 
     Note that the installation method of the solar power system  1  and the solar panel  21  according to the present invention is not limited to the above-mentioned embodiment but modifications may be made to the embodiment as appropriate. 
     For example, not shown, the solar power system  1 , may configure a mega solar system by arranging a plurality of solar panel groups  2  in left-right direction and/or in the front-back direction. Furthermore, when a plurality of solar panel groups  2 ,  2  . . . are installed, the inclination angle θ and/or the inclined direction of each of the solar panel groups  2 ,  2  . . . may be different. 
     In addition, as shown in  FIG. 5 , when installed on an area having ups and downs of hilly area etc., the solar panel group  2 B may be installed so that each of the solar panels  21 ,  21  . . . has level-differences in the vertical direction in a way to draw a curve along the geographical shape. 
     REFERENCE SIGNS LIST 
     
         
           1  solar power system 
           2  solar panel group 
           3  frame 
           4  current collector 
           21  solar panel 
           22  lighting face 
           31  base portion 
           32  frame body 
           33  panel installation rail 
           34  inclination portion 
           41  junction box 
           42  power conditioner 
         θ inclination angle 
         O clearance 
         W width of a solar panel