Abstract:
A solar cell panel includes a light-pervious substrate, a photo-catalyst film, a light source and at least one solar cell. The substrate has a bottom surface and an opposite top surface. The photo-catalyst film is formed on the bottom surface. The light source is configured for emitting light having a given wavelength to activate the photo-catalyst film to decompose contaminants thereon. The at least one solar cell is positioned on the top surface of the substrate to absorb and convert light into electric energy.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to solar cell panels, and particularly to a solar cell panel having self-cleaning capability. 
         [0003]    2. Description of Related Art 
         [0004]    Photovoltaic devices, i.e., solar cells, are capable of converting solar light into usable electric energy. The energy conversion occurs as the result of what is known as the photovoltaic effect. Solar light impinging on the solar cell and absorbed by an active region of semiconductor material generates electricity. 
         [0005]    The solar cell offers a clean and effective inexhaustible source of energy. Particularly, the solar cell installed on a roof of a house has been recently proposed and gradually progressed to spread. However, such solar cell may easily be polluted by many kinds of contaminants in the air. The contaminants may be deposited on surfaces of the solar cell, thus restricting solar light from efficiently impinging the solar cell and decreasing the converting efficiency of the solar cell. 
         [0006]    What is needed, therefore, is a solar cell panel which can overcome the above shortcomings. 
       SUMMARY 
       [0007]    A solar cell panel includes a light-pervious substrate, a photo-catalyst film, a light source and at least one solar cell. The substrate has a bottom surface and an opposite top surface. The photo-catalyst film is formed on the bottom surface. The light source is configured for emitting light having a given wavelength to activate the photo-catalyst film to decompose contaminants thereon. The at least one solar cell is positioned on the top surface to absorb and convert light into electric energy. 
         [0008]    Other advantages and novel features of the present solar cell panel will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Many aspects of the present solar cell panel can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present solar cell panel. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0010]      FIG. 1  is a schematic view of a solar cell panel, in accordance with an exemplary embodiment. 
           [0011]      FIG. 2  is a schematic, side view of the solar cell panel of  FIG. 1 . 
           [0012]      FIG. 3  is similar to  FIG. 2 , but showing an alternative embodiment of the solar cell panel. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0013]    Referring to  FIG. 1 , a solar cell panel  100 , in accordance with a first embodiment, includes a light-pervious substrate  11 , a plurality of solar cell  12 , a plurality of light sources  13 , and a photo-catalyst film  14 . 
         [0014]    The substrate  11  includes a bottom surface  11   a , a top surface  11   b  and four peripheral side surfaces  11   c . The top surface  11   b  is opposite to the bottom surface  11   a . The peripheral side surfaces  11   c  are interconnected between the bottom surface  11   a  and the top surface  11   b . The substrate  11  is made of light-pervious materials, such as glass or plastic selected from a group consisting of polymethylmethacrylate (PMMA), poly carbonate, and silicone, etc. The photo-catalyst film  14  is formed on the bottom surface  11   a , and exposed to air for decomposing contaminants deposited thereon. The photo-catalyst film  14  can be made of nanometer sized photo-catalyst material, such as tin oxide (SnO 2 ), zinc oxide (ZnO), tungsten oxide (WO 3 ), iron oxide (Fe 2 O 3 ), SeTiO 3 , cadmium selenide (CdSe), KTaO 3 , cadmium sulfide (CdS) or niobium oxide (Nb 2 O 5 ), etc. Preferably, the photo-catalyst film  14  is made of titanium dioxide (TiO 2 ) and formed on the bottom surface  11   a  by magnetron sputtering or electron beam deposition. 
         [0015]    Referring to  FIGS. 1 and 2 , the solar cell panel  100  further includes a plurality of transparent conductive films  16  made of materials such as indium tin oxide (ITO), or indium zinc oxide (IZO). The transparent conductive films  16  are formed on the top surface  11   b  by semiconductor process. The solar cells  12  are used to convert light into usable electric energy, and are fixed to the substrate  11  with the transparent conductive films  16 . The transparent conductive films  16  can be used to electrically connect the solar cell  12 . The solar cell panel  100  may further include an electricity storage device (not shown), such as a storage battery electrically connected to the transparent conductive films  16 . Thus, when the solar cell  12  converts light into electric energy, the electric energy can be stored in the electricity storage. The electric energy can be used to supply power to the light sources  13 . 
         [0016]    The solar cell  12  can be a silicon-based solar cell made of single crystal silicon, poly silicon or amorphous silicon. A material used for the solar cell  12  can also be selected from subgroup III-V semiconductor compounds, such as AlAs, InAs, InP, GaP, GaAs, GaN, and copper indium gallium selenide (CIGS), copper indium selenide (CIS), cadmium-tellurium (CdTe), organic material and dye-sensitized material, etc. 
         [0017]    The light sources  13  can be ultraviolet (UV) lamps, such as UV fluorescent lamps and UV light emitting diodes. Preferably, the light sources  13  are UV light emitting diodes, and emit UV light with wavelength of less than 387 nm. In the present embodiment, the light sources  13  are arranged on the peripheral side surfaces  11   c , and emit light into the substrate  11  through the peripheral side surfaces  11   c . The light is transmitted by the substrate  11  and exit through the bottom surface  11   a  thereof, to be incident on the photo-catalyst film  14  thereon. Alternatively, a plurality of receiving recesses  130  can be defined on the peripheral side surfaces  11   c  for respectively receiving the light sources  13 . Therefore, the solar cell panel  100  has smaller size, as shown in  FIG. 3 . 
         [0018]    The solar cell panel  100  can be installed on a roof of a house, with the bottom surface  11   a  of the substrate  11  positioned to face outwardly, and the top surface  11   b  positioned to face the roof, such that solar light are received by the photo-catalyst film  14 . The solar light is absorbed by the photo-catalyst film  14 , with other parts of the solar light, such as visible light and infrared light further emitting into the substrate  11  through the bottom surfaces  11   a . The solar light exits through the top surface  11   b , and is then transmitted through the transparent conductive films  16  to the solar cells  12 . The solar cells  12  absorb and convert the solar energy into electric energy. The electric energy is stored in the electricity storage, and then applied to lamps (not shown) to provide illumination. 
         [0019]    In operation, the electric energy can also be applied to the UV light emitting diodes  13 , thus the UV light emitting diodes  13  emit UV light on the photo-catalyst film  14 . The photo-catalyst film  14  absorbs the UV light, and electron-hole pairs are excited from within the photo-catalyst film  14  to a surface thereof, to initiate reduction/oxidation reactions (redox) with organic contaminants adsorbed on the surface, achieving decomposition of the contaminants. Preferably, the UV light emitting diodes  13  can be electrically connected to a control switch  18 , through which the electric energy is controlled by the control switch  18 . Due to the photo-catalyst film  14  being exposed to the emission of the solar light to absorb the UV light, the UV light emitting diodes  13  can be switched off in daytime. In a dark environment/condition, the UV light emitting diodes  13  can be switched on to emit UV light on the photo-catalyst film  14 . Therefore, by the provision of the UV light emitting diodes  13  and the photo-catalyst film  14 , the solar cell panel  100  keeps clean, and energy converting efficiency of the solar cells  12  are ensure. 
         [0020]    It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.