Abstract:
A solar energy module is provided and includes a substrate comprising at least one light diffusion layer and a plurality of light guiding layers adjacent to the light diffusion layer, and solar chips disposed on the lateral surfaces of the substrate. Solar light enters the substrate and is diffused by the light diffusion layer, and the diffused solar light is reflected by an interface of the light diffusion layer and the light guiding layer and is collected by the solar chips. A part of the solar light enters the light guiding layers and is reflected by the interface of the light guiding layers, and the reflected light is collected by the solar chips.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/176,040 filed May 6, 2009. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a solar energy module, and in particular relates to a solar energy module allowing partial solar light to penetrate therethrough. 
         [0004]    2. Description of the Related Art 
         [0005]    When applying conventional solar energy technology, conventional solar energy modules are often disposed on roofs or outer walls of houses or buildings. However, multi-purpose application including use as windows are hindered due to the poor transparency of conventional solar energy modules. 
       BRIEF SUMMARY OF INVENTION 
       [0006]    An embodiment of a solar energy module of the invention comprises a substrate comprising at least one light diffusion layer and a plurality of light guiding layers adjacent to the light diffusion layer, and solar chips disposed on the lateral surfaces of the substrate. Solar light enters the substrate and is diffused by the light diffusion layer, and the diffused solar light is reflected by an interface of the light diffusion layer and the light guiding layer or the composite structure to be collected by the solar chips. A part of the solar light enters the light guiding layers and is reflected by the interface of the light guiding layers, and the reflected light is collected by the solar chips. 
         [0007]    The light guiding layers are made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide, silicon resin or glass. 
         [0008]    The light diffusion layer is made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide or silicon resin. 
         [0009]    The light diffusion layer comprises light scattering particles. 
         [0010]    The light diffusion layer comprises a mixed material of two materials with different index of refractions. 
         [0011]    The light diffusion layer is an optical composite structure. 
         [0012]    A heat insulation layer is preferably formed on a surface of the substrate opposite to the surface of the substrate through which solar light enters the substrate. 
         [0013]    The heat insulation layer has high reflective rate for solar light. 
         [0014]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0016]      FIG. 1  is a schematic view of a solar energy module of the invention; and 
           [0017]      FIG. 2  is a schematic view of the light diffusion layer of the substrate of the solar energy module of the invention; and 
           [0018]      FIG. 3  depicts solar light guided to solar chips by a light diffusion layer and a light guide layer. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0019]    Referring to  FIG. 1 , a solar energy module  1000  comprises a substrate  100  and solar chips  70  disposed on lateral surfaces of the substrate  100 . The substrate  100  comprises a light diffusion layer  10  and light guiding layers  20 ,  30  and  40 . Solar light L enters the light diffusion layer  10 .  FIG. 2  depicts a more detailed structure of the light diffusion layer  10 . Light scattering particles  12  are distributed in the light diffusion layer  10 . When solar light L enters the light diffusion layer  10 , solar light is scattered by the light scattering particles  12 . The scattered light is reflected by the interface of the light diffusion layer  10  to be collected by the solar chips  70 . The particles  12  are preferably transparent but have different index of refractions from the material of the light diffusion layer  10 . 
         [0020]    A part of solar light L penetrates the light diffusion layer  10  to enter the light guiding layer  20  as shown in  FIG. 3 . Since the index of refraction of the light diffusion layer  10  is different from the light guiding layers  20 ,  30  and  40 , the solar light is refracted when the solar light enters the light guiding layer  20 , and the refracted light is reflected by the interface of the light guiding layer  20  and collected by the solar chips  70 . 
         [0021]    The light guiding layers  20 ,  30  and  40  are made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide, silicon resin or glass. The light diffusion layer is made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide or silicon resin. 
         [0022]    A heat insulation layer is preferably formed on the light guiding layer  40 . The heat insulation layer has high reflective rate for solar light and allows a part of solar light to penetrate therethrough. The solar light penetrating the light guiding layer  20 ,  30  and  40  is reflected by the heat insulation layer to be collected by the solar chips  70   m  which increases the efficiency of the solar chips  70 . 
         [0023]    In general, the substrate  10  has four lateral surfaces. The solar chips  70  can be disposed on one, two, three or four lateral surfaces of the substrate  100 . When the solar chips  70  are disposed on two or three lateral surfaces of the substrate  10 , reflective layers can be formed on the other lateral surfaces of the substrate  10 . 
         [0024]    The solar chips can be III-V column solar chips, single crystal silicon solar chips, poly crystal silicon solar chips or CIGS solar chips. 
         [0025]    Transparency of the substrate  10  is 5% to 85% so that solar light is able to penetrate the substrate  10 . The solar energy module of the invention can be applied to windows of buildings, whereby the outside scenery can be viewed by those inside of the building. 
         [0026]    Although the light diffusion layer of the embodiment is in the first layer  10  which receives solar light L in this embodiment, the light diffusion layer can be in the second layer  20 , third layer  30  or fourth layer  40 , or the substrate  100  can comprise a plurality of light diffusion layers. 
         [0027]    Two test examples of the solar energy module are described. 
         [0028]    Test example A comprises a square light diffusion plate with thickness 14 mm, length 170 mm, haze 81 and transparency 45%. The solar chips of efficiency 14% are attached to lateral surfaces of the light diffusion plate to an area of 72 cm 2 . The collection efficiency of the solar module is 1.66%. 
         [0029]    Test example B comprises a square light diffusion plate with thickness 3 mm, length 170 mm, haze 23 and transparency 83%. The light diffusion plate is sandwiched by two glass plate of thickness 5 mm. The solar chips of efficiency 14% are attached to lateral surfaces of the light diffusion plate to an area of 72 cm 2 . The collection efficiency of the solar module is 1.36%. 
         [0030]    Several examples are shown as follows. Some parameters in the examples are varied to show how the solar cell efficiency is varied by the parameters. 
       Example 1 
       [0031]    The substrate comprises only one light diffusion layer but has no light guiding layer. The light diffusion layer is acrylic plate with length 81 mm, width 81 mm, thickness 14 mm and haze 5.7. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 1 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 1 
                 5.7 
                 85.51 
                 80.86 
                 1.01% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.51% 
               
               
                   
               
             
          
         
       
     
       Example 2 
       [0032]    The substrate comprises only one light diffusion layer but has no light guiding layer. The light diffusion layer is acrylic plate with length 81 mm, width 81 mm, thickness 14 mm and haze 11.38. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 2 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 2 
                 11.38 
                 82.31 
                 72.94 
                 1.24% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.51% 
               
               
                   
               
             
          
         
       
     
       Example 3 
       [0033]    The substrate comprises only one light diffusion layer but has no light guiding layer. The light diffusion layer is acrylic plate with length 81 mm, width 81 mm, thickness 14 and haze 38.7. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 3 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 3 
                 38.70 
                 64.99 
                 39.84 
                 2.19% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.51% 
               
               
                   
               
             
          
         
       
     
       Example 4 
       [0034]    The substrate comprises only one light diffusion layer but has no light guiding layer. The light diffusion layer is acrylic plate with length 81 mm, width 81 mm, thickness 14 and haze 78.77. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 4 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 4 
                 78.77 
                 47.64 
                 10.11 
                 3.40% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.51% 
               
               
                   
               
             
          
         
       
     
       Example 5 
       [0035]    The substrate comprises only one light diffusion layer but has no light guiding layer. The light diffusion layer is acrylic plate with length 168 mm, width 168 mm, thickness 14 and haze 36.56. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 5 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 5 
                 36.56 
                 66.58 
                 42.24 
                 0.88% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
       Example 6 
       [0036]    The substrate comprises only one light diffusion layer but has no light guiding layer. The light diffusion layer is acrylic plate with length 168 mm, width 168 mm, thickness 14 and haze 81.88. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 6 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 6 
                 81.88 
                 41.81 
                 7.58 
                 1.45% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
         [0037]    In examples 1˜6, the substrate has only one light diffusion layer but without the light guiding layer. The following examples has light guiding layers. 
       Example 7 
       [0038]    The substrate comprises one light diffusion layer (polycarbonate layer) and one light guiding layer (acrylic plate) disposed on the light diffusion layer. The light diffusion layer has length 81 mm, width 81 mm, thickness 3 and haze 78.77. The light guiding layer has a thickness of 10 mm. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 7 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 7 
                 78.77 
                 61.49 
                 30.58 
                 2.36% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.51% 
               
               
                   
               
             
          
         
       
     
       Example 8 
       [0039]    The substrate comprises one light diffusion layer (polycarbonate layer) and one light guiding layer (glass plate) disposed on the light diffusion layer. The light diffusion layer has length 168 mm, width 168 mm, thickness 3 and haze 36.05. The light guiding layer has a thickness of 10 mm. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 8 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 8 
                 78.77 
                 61.49 
                 30.58 
                 2.36% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
       Example 9 
       [0040]    The substrate comprises one light diffusion layer (polycarbonate layer) and one light guiding layer (glass plate) disposed on the light diffusion layer. The light diffusion layer has length 168 mm, width 168 mm, thickness 3 and haze 50.26. The light guiding layer has a thickness of 10 mm. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 9 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 9 
                 50.26 
                 61.49 
                 30.58 
                 1.55% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
       Example 9a 
       [0041]    The substrate comprises one light diffusion layer (polycarbonate layer) and one light guiding layer (glass plate) disposed on the light diffusion layer. The light diffusion layer has length 168 mm, width 168 mm, thickness 3 and haze 50.26. The light guiding layer has a thickness of 10 mm. A white screen is disposed beneath the light diffusion layer, which is to simulate a curtain behind the window glass. Solar cells are attached to four lateral side of the substrate. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 9a 
                 50.26 
                 61.49 
                 30.58 
                 2.61% 
               
               
                   
               
             
          
         
       
     
         [0042]    In the following examples, the light diffusion layer is sandwiched by two light guiding layers. 
       Example 10 
       [0043]    The substrate comprises one light diffusion layer (polycarbonate layer) and two light guiding layers (glass plate) sandwiching the light diffusion layer. The light diffusion layer has length 168 mm, width 168 mm, thickness 3 and haze 15.18. The light guiding layers have a thickness of 5 mm. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 10 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 10 
                 15.18 
                 88.33 
                 74.92 
                 0.51% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
       Example 11 
       [0044]    The substrate comprises one light diffusion layer (polycarbonate layer) and two light guiding layers (glass plate) sandwiching the light diffusion layer. The light diffusion layer has length 168 mm, width 168 mm, thickness 3 and haze 36.05. The light guiding layers have a thickness of 5 mm. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 11 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 11 
                 36.05 
                 67 
                 30.58 
                 0.57% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
       Example 12 
       [0045]    The substrate comprises one light diffusion layer (polycarbonate layer) and two light guiding layers (glass plate) sandwiching the light diffusion layer. The light diffusion layer has length 168 mm, width 168 mm, thickness 3 and haze 50.26. The light guiding layers have a thickness of 5 mm. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 12 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 12 
                 50.26 
                 61.49 
                 30.58 
                 0.81% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
       Example 13 
       [0046]    The substrate comprises one light diffusion layer (polycarbonate layer) and two light guiding layers (glass plate) sandwiching the light diffusion layer. The light diffusion layer has length 168 mm, width 168 mm, thickness 3 and haze 64.31. The light guiding layers have a thickness of 5 mm. Solar cells are attached to four lateral side of the substrate. A conventional commercial acrylic plate, which has the same size as the example 13 but is totally transparent, is set to be a control. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 13 
                 64.31 
                 42.94 
                 27.61 
                 1.23% 
               
               
                 Control 
                 0.88 
                 91.89 
                 91.08 
                 0.06% 
               
               
                   
               
             
          
         
       
     
       Example 14 
       [0047]    The substrate comprises one light diffusion layer (polycarbonate layer) and two light guiding layers (glass plate) sandwiching the light diffusion layer. The light diffusion layer has length 275 mm, width 220 mm, thickness 3 and haze 20.13. The light guiding layers have a thickness of 5 mm. Solar cells are attached to four lateral side of the substrate. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 14 
                 20.13 
                 77.07 
                 61.55 
                 0.68% 
               
               
                   
               
             
          
         
       
     
       Example 14a 
       [0048]    The substrate comprises one light diffusion layer (polycarbonate layer) and two light guiding layers (glass plate) sandwiching the light diffusion layer. The light diffusion layer has length 275 mm, width 220 mm, thickness 3 and haze 20.13. The light guiding layers have a thickness of 5 mm. A white screen is disposed beneath the light diffusion layer, which is to simulate a curtain behind the window glass. Solar cells are attached to four lateral side of the substrate. The efficiency is show as follows. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Total 
                 Parallel 
                   
               
               
                   
                 Haze 
                 Transparency 
                 Transparency 
                 Efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 14a 
                 20.13 
                 77.07 
                 61.55 
                 1.11% 
               
               
                   
               
             
          
         
       
     
         [0049]    In the examples 1˜4, the efficiency is increased by increasing the haze. In the examples 3˜4, the larger is the substrate, the efficiency is lower. In the examples 3 and 8, the multiple layers structure has a better efficiency than the single layer structure in the same haze. 
         [0050]    While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.