Abstract:
A photovolataic cell powered by artificial lights, wherein photovoltaic cell and artificial lights use a light guide to distribute light onto the photovoltaic cell while maintaining an overall compact shape.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    This disclosure relates in general to generating power with photovoltaic cells using artificial light. 
         [0003]    2. Brief Description of Related Art 
         [0004]    Photovoltaic (“PV”) cells produce electricity when exposed to light. PV cells are commonly used as solar cells, wherein the light is provided by the sun. A solar cell only produces electricity when exposed to sunlight and thus is less useful on overcast days and do not produce any electricity at night. Furthermore, a cluster or array of solar cells must be used to produce large quantities of electricity. An array of cells with solar exposure may take up considerable geographic space and may not be practical for use in a small space such as an urban area or in a vehicle. Therefore, it is desirable to have PV cells that do not require exposure to sunlight to produce power. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is an illustration of an exemplary embodiment of a power unit, wherein the light guide is lifted away from the photovoltaic panel for illustrative purposes. 
           [0006]      FIG. 2  is an illustration of an exemplary embodiment of a power unit. 
           [0007]      FIG. 3  is a sectional view of the power unit of  FIG. 2 , taken along the  3 - 3  line. 
           [0008]      FIG. 4  is a side view of an assembly comprising two photovoltaic panels and one light guide in an exemplary embodiment. 
           [0009]      FIG. 5  is a diagram of a power unit and components in an exemplary embodiment. 
           [0010]      FIG. 6  is a side view of multiple power units stacked together in an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    In the drawings and description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention is susceptible to embodiments of different forms. Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. The various characteristics mentioned above, as well as other features and characteristics described in more detail below, will be readily apparent to those skilled in the art upon reading the following detailed description of the embodiments, and by referring to the accompanying drawings. 
         [0012]    Referring to  FIG. 1 , a power unit  100  comprises a photovoltaic panel  110 , a light guide  112 , and an artificial light source  114 . A photovoltaic (“PV”) panel  110  comprises one or more PV cells  116 , mounted on a support structure  118 . The PV panel  110  may be a commercially available unit. The PV cells  116  produce electricity when exposed to light. In an exemplary embodiment, the PV panel  110  is a commercial panel with a rated output of 175 watts (“W”). Multiple PV cells  116  may be present on one panel, each connected to a common power output connection. 
         [0013]    An artificial light source  114  provides light for the PV panel  110 . In an exemplary embodiment, the artificial light source  114  comprises one or more light emitting diodes (“LED”). Any other electrically powered light source may be used including, for example, incandescent, halogen, fluorescent, a laser, and the like. The artificial light source  114  is attached to the edge or edges of a light guide  112 . 
         [0014]    The shape of the Power Units  100  is not limited to the shape of a commercially available PV panel  110 . The Power Units  100  may have rounded edges, a generally concave shape, or any other external shape, depending on the requirements of the user. A Power Unit  100  could, for example, could be located in a vehicle and thus have a size and shape determined by the size of a compartment on the vehicle. 
         [0015]    Referring to  FIG. 2 , in an exemplary embodiment, light emitting diodes (LED)  214  are located along the exterior edge of the optical waveguide (light guide)  212 . A light guide  212  is a device that reflects and distributes the light to the photovoltaic panel  210 . The height, or thickness, of a light guide may be less than 1″ regardless of the length and width of the light guide. The LEDs  214  beam light into the interior of the light guide  212  where the light is distributed and then focused out through the bottom facing side onto the surface of the photovoltaic panel  210 . The amount of light can be varied based on the number of LEDs  214  affixed to the exterior edge of the light guide  212 . 
         [0016]    The light guide  212  with its LEDs  214  may be attached to the surface of the photovoltaic panel  210  by any means, including bonding, mechanical fasteners, and the like. The light emitting surface  324  ( FIG. 3 ) is in contact or in very close proximity to the PV cells  116  ( FIG. 1 ). 
         [0017]    An assembled unit comprising a PV panel  210 , lights  214 , and a light guide  212  is called a “Power Unit”  226 . In an exemplary embodiment, the length, width, and height of the Power Unit  226  is determined by the length and width of a commercially available PV panel  210 . In an exemplary embodiment, the Power Unit  226  is approximately 63″ by 31″. The length and width could be larger or smaller depending on the size of the PV panel  210 . Furthermore, multiple PV panels  210  could be joined together thus giving the Power Unit  226  a length or width that is larger than a single PV panel  210 . The height of the Power Unit  226 , comprising the height of the PV panel  210  plus the height of the light guide  212 , may be any thickness, including approximately 2″ or 3″. The small overall height is achieved by using the light guide to distribute the light to the PV panel  210 . The height could be taller or shorter depending on the thickness of the PV panel  210  and light guide  212 . 
         [0018]    Referring to  FIG. 3 , the light guide  312  is a flat panel that reflects the artificial light onto the surface of the PV panel  310 . Light emitted by the artificial light source  314  goes into the light guide  320 . The light guide  320  reflects and evenly distributes the light through the light emitting surface  324  onto the PV panel  310 . 
         [0019]    The light guide  312 , also referred to as an optical wave guide, is a physical structure that guides electromagnetic waves in the optical spectrum. This device can be utilized as a means for providing illumination over the surface of the PV panel  310 . In an exemplary embodiment, the light guide is a piece of glass that is a few millimeters thick, with embedded reflective material. Common types of optical waveguides  312  include optical fiber and rectangular waveguides. 
         [0020]    The light guide  312  may have a reflective surface  320  on an exterior surface or edge. In an exemplary embodiment, a single light guide  312  is affixed to a single PV panel  310 . The top of the light guide, the side not facing the PV panel  310 , may be covered with a reflective coating  320  to direct light back into the light guide and onto the PV panel  310 . 
         [0021]    Referring to  FIG. 4 , in an alternative embodiment, a single light guide  412  illuminates two PV panels  410 , forming a dual power unit  402  Two PV panels  410  are attached to the single light guide  412 , one on the top and one on the bottom. The light guide  412  emits light from both its top  426  and bottom  424  surfaces. Thus a single set of lights  414  can illuminate two PV panels  410 . 
         [0022]    Referring to  FIG. 5 , in an exemplary embodiment, an external power supply  530  is used to provide the initial power to the artificial light  514 . The power supply  530  could be from any direct current (“DC”) power source including, for example, a battery, a wind turbine, alternating current (“AC”) from a power line converted to DC, and the like. The power from the external power supply  530  may go through a control module  532 . After the external power supply  530  provides power to the artificial light  514 , the light  534  passes through the light guide  512 , which reflects the reflected light  536  to the PV panel  510 . The light  536  causes the PV panel  510  to produce more power than the artificial lights  514  consume. In an exemplary embodiment, the electricity from the PV panel output  538  is used to power the artificial lights  514 , thus making the unit self-powered. A control module  532  or manual control may be used to stop the external power  530  when the Power Unit  500  becomes self powered. 
         [0023]    In an exemplary embodiment, the power output  538  from the Power Unit  500  is self limiting based on the brightness of the artificial light source  514 . In some embodiments, a voltage regulator  540  may be used to achieve a specific output voltage. The voltage may be higher or lower than the original output  538  voltage of the PV panel. Furthermore, an inverter  542  may be used to convert the Power Unit&#39;s  500  DC output to an AC output. The power output ultimately powers an electrical device, or load  544 . 
         [0024]    Referring to  FIG. 6 , Multiple Power Units  626  may be combined to form a power unit cluster  604  to increase the total power output  538  ( FIG. 5 ). The Power Units  626  could, for example, be stacked on top of each other or be standing on end adjacent to each other. The electricity from the Power Units  626  may be combined in series to increase voltage, or in parallel to increase amperage, or both. 
         [0025]    The output of a PV cell may be increased by exposing it to light having a particular wavelength. A PV cell is typically made of a doped silicon crystal. PV cells have a “band gap,” which is defined as the amount of energy needed to knock an electron loose. The unit of measure for this is electron volts (eV). The band gap varies from one type of PV cell to another, depending on the dopant used in the silicon crystal. The optimal band gap for an exemplary PV cell is typically 1.4 eV. 
         [0026]    The optimal wavelength for PV cell performance can be determined as follows:
   Assume a band gap of 1.4 eV.   Electromagnetic spectrum eV reference:
       Ultraviolet=3.2-100 eV   Visible Light=1.6-3.2 eV   Infrared=1.2 meV-1.7 eV   
       Electromagnetic spectrum wavelength (λ) reference:
       Visible Light=400-700 nm   Infrared=700 nm-1 mm
           Near Infrared (“NIR”)=2500-750 nm   Medium Infrared (“MIR”)=110-2.5 μm   Far Infrared (“FIR”)=1 mm-110 μm   
           
       Electromagnetic spectrum frequency (ν) reference:   
 
         [0039]    Visible Light=400-790 THz
       Infrared=300 GHz-400 THz
           NIR=112-400 THz   MIR=226-112 THz   FIR=300 GHz−30 THz   
               Definitions and constants:
       C=speed of light 299,792,458 m/s   E=energy of photon   ν=frequency   E=hν (Planck relation)   Planck constant: h=6.62609896*110 −34  J
           S=4.135667*110 −15  eVs   
           λ=wavelength   ν=E/h   λ=C/ν   
       Calculations: Determining the optimal wave length associated with a photovoltaic cell having a band gap of 1.4 eV.
       ν=1.4 eV/4.13566733*110 −15  eVs   ν=340 THz   λ=299,792,458/340   λ=881 nm   
       
 
         [0059]    Thus the best wavelength of light for a band gap of 1.4 eV is 881 nm, which is located in the Near Infrared (“NIR”) portion of the electromagnetic spectrum. The nearest commercially available light has a wavelength of 880 nm, which is located in the Near Infrared (NIR) portion of the electromagnetic spectrum. The 880 nm light is not visible to the human eye, but still provides power to a PV cell. 
         [0060]    When a light source, such as an LED, provides light to a PV cell at the PV cell&#39;s optimal wavelength, the PV cell may produce more power than the light source consumes. The following table shows the results from an exemplary experimental embodiment of the photovoltaic panel  110  and artificial light source  114  depicted in  FIGS. 1-3 .
   “Time” indicates the time at which the reading was taken during the test.   “Panel Output(V)” shows voltage output from the PV cell in volts.   “LED Consumption(V)” shows voltage applied to the LEDs in volts.   “Panel Output(A)” shows current produced by the PV cell in amps.   “LED Consumption(A)” shows current consumed by the LEDs in amps.   
 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Panel 
                   
                 Panel 
                   
               
               
                   
                 Output 
                 LED 
                 Output 
                 LED 
               
               
                 Time 
                 (V) 
                 Consumption (V) 
                 (A) 
                 Consumption (A) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 10:00:48 AM 
                 37.06 
                 9.71 
                 4.72 
                 0.268 
               
               
                 10:01:48 AM 
                 37.04 
                 9.70 
                 4.72 
                 0.268 
               
               
                 10:02:48 AM 
                 37.00 
                 9.71 
                 4.73 
                 0.268 
               
               
                 10:03:48 AM 
                 36.97 
                 9.71 
                 4.73 
                 0.268 
               
               
                 10:04:48 AM 
                 36.92 
                 9.69 
                 4.74 
                 0.268 
               
               
                 10:05:48 AM 
                 36.89 
                 9.70 
                 4.74 
                 0.268 
               
               
                 10:06:48 AM 
                 36.85 
                 9.72 
                 4.75 
                 0.267 
               
               
                 10:07:48 AM 
                 36.80 
                 9.75 
                 4.76 
                 0.267 
               
               
                 10:08:48 AM 
                 36.76 
                 9.73 
                 4.76 
                 0.267 
               
               
                 10:09:48 AM 
                 36.74 
                 9.73 
                 4.76 
                 0.267 
               
               
                 10:10:48 AM 
                 36.72 
                 9.71 
                 4.77 
                 0.268 
               
               
                 10:11:48 AM 
                 36.73 
                 9.70 
                 4.76 
                 0.268 
               
               
                 10:12:48 AM 
                 36.71 
                 9.71 
                 4.77 
                 0.268 
               
               
                 10:13:48 AM 
                 36.68 
                 9.72 
                 4.77 
                 0.267 
               
               
                 10:14:48 AM 
                 36.66 
                 9.68 
                 4.77 
                 0.269 
               
               
                 10:15:48 AM 
                 36.60 
                 9.67 
                 4.78 
                 0.269 
               
               
                 10:16:48 AM 
                 36.58 
                 9.67 
                 4.78 
                 0.269 
               
               
                 10:17:48 AM 
                 36.50 
                 9.70 
                 4.79 
                 0.268 
               
               
                 10:18:48 AM 
                 36.42 
                 9.64 
                 4.81 
                 0.270 
               
               
                 10:19:48 AM 
                 36.38 
                 9.65 
                 4.81 
                 0.269 
               
               
                 10:20:48 AM 
                 36.30 
                 9.64 
                 4.82 
                 0.270 
               
               
                 10:21:48 AM 
                 36.27 
                 9.64 
                 4.82 
                 0.270 
               
               
                 10:22:48 AM 
                 36.21 
                 9.61 
                 4.83 
                 0.271 
               
               
                 10:23:48 AM 
                 36.20 
                 9.57 
                 4.83 
                 0.272 
               
               
                 10:24:48 AM 
                 36.18 
                 9.60 
                 4.84 
                 0.271 
               
               
                 10:25:48 AM 
                 36.18 
                 9.59 
                 4.84 
                 0.271 
               
               
                 10:26:48 AM 
                 36.20 
                 9.59 
                 4.83 
                 0.271 
               
               
                 10:27:48 AM 
                 36.21 
                 9.59 
                 4.83 
                 0.271 
               
               
                 10:28:48 AM 
                 36.17 
                 9.60 
                 4.84 
                 0.271 
               
               
                 10:29:48 AM 
                 36.09 
                 9.60 
                 4.85 
                 0.271 
               
               
                 10:30:48 AM 
                 36.24 
                 9.61 
                 4.83 
                 0.271 
               
               
                 10:31:48 AM 
                 36.27 
                 9.60 
                 4.82 
                 0.271 
               
               
                 10:32:48 AM 
                 36.26 
                 9.60 
                 4.83 
                 0.271 
               
               
                 10:33:48 AM 
                 36.26 
                 9.63 
                 4.83 
                 0.270 
               
               
                 10:34:48 AM 
                 36.26 
                 9.62 
                 4.83 
                 0.270 
               
               
                 10:35:48 AM 
                 36.28 
                 9.61 
                 4.82 
                 0.271 
               
               
                 10:36:48 AM 
                 36.31 
                 9.62 
                 4.82 
                 0.270 
               
               
                 10:37:48 AM 
                 36.30 
                 9.59 
                 4.82 
                 0.271 
               
               
                 10:38:48 AM 
                 36.34 
                 9.60 
                 4.82 
                 0.271 
               
               
                 10:39:48 AM 
                 36.32 
                 9.61 
                 4.82 
                 0.271 
               
               
                 10:40:48 AM 
                 36.38 
                 9.59 
                 4.81 
                 0.271 
               
               
                 10:41:48 AM 
                 36.36 
                 9.59 
                 4.81 
                 0.271 
               
               
                 10:42:48 AM 
                 36.39 
                 9.61 
                 4.81 
                 0.271 
               
               
                 10:43:48 AM 
                 36.43 
                 9.60 
                 4.80 
                 0.271 
               
               
                 10:44:48 AM 
                 36.45 
                 9.60 
                 4.80 
                 0.271 
               
               
                 10:45:48 AM 
                 36.43 
                 9.63 
                 4.80 
                 0.270 
               
               
                 10:46:48 AM 
                 36.45 
                 9.60 
                 4.80 
                 0.271 
               
               
                 10:47:48 AM 
                 36.46 
                 9.60 
                 4.80 
                 0.271 
               
               
                 10:48:48 AM 
                 36.46 
                 9.60 
                 4.80 
                 0.271 
               
               
                 10:49:48 AM 
                 36.45 
                 9.60 
                 4.80 
                 0.271 
               
               
                 10:50:48 AM 
                 36.49 
                 9.60 
                 4.80 
                 0.271 
               
               
                 10:51:48 AM 
                 36.49 
                 9.59 
                 4.80 
                 0.271 
               
               
                 10:52:48 AM 
                 36.51 
                 9.60 
                 4.79 
                 0.271 
               
               
                 10:53:48 AM 
                 36.53 
                 9.58 
                 4.79 
                 0.271 
               
               
                 10:54:48 AM 
                 36.54 
                 9.58 
                 4.79 
                 0.271 
               
               
                 10:55:48 AM 
                 36.57 
                 9.58 
                 4.79 
                 0.271 
               
               
                 10:56:48 AM 
                 36.62 
                 9.57 
                 4.78 
                 0.272 
               
               
                 10:57:48 AM 
                 36.60 
                 9.57 
                 4.78 
                 0.272 
               
               
                 10:58:48 AM 
                 36.59 
                 9.57 
                 4.78 
                 0.272 
               
               
                 10:59:48 AM 
                 36.60 
                 9.58 
                 4.78 
                 0.271 
               
               
                 11:00:48 AM 
                 36.64 
                 9.56 
                 4.78 
                 0.272 
               
               
                   
               
             
          
         
       
     
         [0066]    The table shows that the PV panel in the exemplary experimental embodiment produced a higher voltage and amperage, and thus more power, than the LEDs consumed. 
         [0067]    It is understood that variations may be made in the above without departing from the scope of the invention. While specific embodiments have been shown and described, modifications can be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments as described are exemplary only and are not limiting. One or more elements of the exemplary embodiments may be combined, in whole or in part, with one or more elements of one or more of the other exemplary embodiments. Many variations and modifications are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.