Abstract:
A system and method for increasing photovoltaic cell efficiency is provided, comprising a photovoltaic cell, a filter covering the photovoltaic cell at a first angle to the photovoltaic cell, and a mirror positioned adjacent to the filter at a second angle to the photovoltaic cell, the mirror operable to reflect light into the filter.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a system and method for improving photovoltaic cell efficiency by the use of one or more filters. 
     BACKGROUND OF THE INVENTION 
     Photovoltaic cells provide clean, non-polluting energy by converting light, either natural sunlight or artificial light, into electricity. Photovoltaic cell efficiency has increased, but photovoltaic cells still do not convert 100% of available light into electricity. At best, photovoltaic cells in a laboratory environment may convert 50% of light into electricity. Commercially available photovoltaic cells may have an efficiency closer to 30%. Photovoltaic cell efficiency is dependent on, for example, the chemical makeup of the photovoltaic cell, the wavelengths of light that reach the photovoltaic cell, and the temperature of the photovoltaic cell. 
     Photovoltaic cells may have a range of efficiency, and may not convert the entire light spectrum into electricity with equal efficiency. Photovoltaic cells may only convert discrete wavelengths or ranges of wavelengths of light energy into electricity, and may not convert certain wavelengths of light energy into electricity at all. For example, some photovoltaic cells may not convert visible light into electricity. Additionally, different photovoltaic cell compositions may be more efficient at converting different wavelengths of light energy into electricity. For example, silicon photovoltaic cells may be most efficient (i.e., convert the largest percentage of available light energy into electricity) when the wavelength of light is approximately 980-1180 nanometers. Gallium arsenide photovoltaic cells may be most efficient at a different wavelength range. Photovoltaic cells may also work most efficiently in a certain range of operating temperatures. A photovoltaic cell may be most efficient at, for example, 70 degrees Fahrenheit, and may not be as efficient at, for example, −20 degrees Fahrenheit or at 100 degrees Fahrenheit. 
     Light which is not converted to electricity may be absorbed, reflected, or transmitted through the photovoltaic cell. Light energy absorbed by the photovoltaic cell but not converted into electricity may be converted into heat energy. This heat energy may warm the photovoltaic cell, and may move the photovoltaic cell out of the optimum temperature range for maximum efficiency. This decreased efficiency may not be desirable from an operational standpoint, or may even adversely affect the lifespan of the photovoltaic cell. 
     SUMMARY OF THE INVENTION 
     Accordingly, various embodiments of the present invention directed to a system and method for photovoltaic cell efficiency improvements are provided. An apparatus may comprise a filter, a first mirror, a second mirror, a photovoltaic cell, a first support, and a second support. The filter may allow light energy of specific wavelengths to be transmitted to the photovoltaic cell, which may at least approximately overlap with the photovoltaic cell&#39;s band gap properties. The filter, the first mirror, the second mirror, the photovoltaic cell, the first support, and the second support may be arranged so that light energy may strike the filter. Such light energy may be selectively transmitted through the filter, or may be selectively absorbed or reflected by the filter, depending on the filter&#39;s transmission properties. Light energy may strike the first mirror and be substantially reflected or partially reflected into the filter, where the remaining light energy may be transmitted or reflected or absorbed according to the properties of the filter. The transmitted light energy may strike the second mirror and be substantially or partially reflected onto the photovoltaic cell. The photovoltaic cell may thus be exposed to light energy corresponding to the photovoltaic cell&#39;s band gap properties, and the waste light energy that the photovoltaic cell may not properly convert into electricity or may inefficiently convert into electricity may be absorbed or reflected by the filter, the first mirror, or the second mirror, or a combination thereof. 
     In an alternate embodiment, an apparatus may comprise a first filter, a first photovoltaic cell, a first mirror, a second mirror, a second photovoltaic cell, and a second filter. The first photovoltaic cell may be positioned underneath the first filter and adjacent to the first mirror, and the second photovoltaic cell may be positioned underneath the second filter and adjacent to the second mirror. The filters may have dichroic properties. The first dichroic filter and the second dichroic filter may have distinct transmission profiles, so that light energy reflected by the first dichroic filter may be transmitted by the second dichroic filter, and light reflected by the second dichroic filter may be transmitted by the first dichroic filter, Additionally, the first photovoltaic cell and the second photovoltaic cell may have substantially distinct band gap properties, so that the band gap of the first photovoltaic cell is partially or substantially different than the band gap of the second photovoltaic cell. Light energy may strike the first dichroic filter and the second dichroic filter, and may be reflected or transmitted according to the transmission profile of the first dichroic filter and the second dichroic filter. The light energy initially reflected by the first dichroic filter or the second dichroic filter may be reflected into each other, so that the second dichroic filter receives reflected light energy from the first dichroic filter and vice versa. The light energy may be selectively transmitted or reflected according to the transmission profiles of the first dichroic filter and the second dictiroic filter. Each photovoltaic cell may thus be exposed to light energy corresponding to the photovoltaic cell&#39;s band gap properties, and the waste light energy that the photovoltaic cell may not properly convert into electricity or may inefficiently convert into electricity may be absorbed or reflected by the first dichroic filter and the second dichroic filter. 
     Other embodiments are also within the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention, together with further objects and advantages, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several Figures of which like reference numerals identify like elements, and in which: 
         FIG. 1  is a side view of a photovoltaic cell efficiency improvement apparatus, according to one embodiment of the present invention; 
         FIG. 1   a  is a side offset view of a photovoltaic cell efficiency improvement apparatus, according to one embodiment of the present invention; 
         FIG. 2  is a side view of a photovoltaic cell efficiency improvement apparatus, showing exemplary light rays according to one embodiment of the present invention; 
         FIG. 3  is a side view of a dual cell photovoltaic cell efficiency improvement apparatus according to one embodiment of the present invention; and 
         FIG. 4  is a side view of a duel cell photovoltaic cell efficiency improvement apparatus, showing exemplary light rays according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is intended to convey a thorough understanding of the embodiments described by providing a number of specific embodiments and details involving systems and methods for increased photovoltaic cell efficiency. It should be appreciated, however, that the present invention is not limited to these specific embodiments and details, which are exemplary only. It is further understood that one possessing ordinary skill in the art, in light of known systems and methods, would appreciate the use of the invention for its intended purposes and benefits in any number of alternative embodiments, depending on specific design and other needs. 
     Turning to  FIG. 1 , a side view of a photovoltaic cell efficiency improvement apparatus  100  is shown according to one embodiment of the present invention. 
     The filter  110  may extend over the photovoltaic cell  130 , so that, for example, the filter  110  is substantially the same area as the photovoltaic cell  130 . The filter  110  and the photovoltaic cell  130  may abut one another, forming an angle depicted in  FIG. 1  as β. The angle β is preferably in the range of 40 to 50 degrees, and is most preferably substantially 45 degrees. The filter  10  may be formed from a selectively transparent material, so that light energy striking the filter  10  may be selectively allowed to pass, and selectively reflected or absorbed, depending on the wavelength of the light energy. For example, the filter  110  may be formed from a material known as a “1×26” light filter, manufactured or distributed by Rosco Laboratories, Inc. The material may have properties which allow light energy having a wavelength greater than approximately 760 nanometers to pass through the filter  110 , and the filter  110  may absorb or reflect light energy of approximately less than 760 nanometers. Waste light energy may be defined as light energy which is absorbed or reflected by the filter  110 . In the current example, the waste light energy has the wavelength range of less than 760 nanometers. The filter  110  may substantially absorb the waste light energy, or may substantially reflect the waste light energy. Of course, other filters having other light selection properties may be used. A filter  110  and photovoltaic cell  130  pair in which light energy having wavelengths overlapping or otherwise matching the photovoltaic cell&#39;s efficiency range is allowed to pass through the filter may be desirable. 
     The photovoltaic cell  130  may extend underneath the filter  110  so that, for example, the photovoltaic cell  130  may be approximately the same area as the filter  110 . The photovoltaic cell  130  may be operable to convert light energy striking the photovoltaic cell  130  into electricity. The process by which the photovoltaic cell  130  converts light energy into electricity, and the mechanism that removes electricity from of the photovoltaic cell  130  and processes the electricity to accomplish work, is well known in the art. With the filter  110  described above, filtering much of the light energy having a wavelength below  760  nanometers, one choice of photovoltaic cell  130  is a silicon photovoltaic cell. A silicon photovoltaic cell  130  may have a range of efficiency or a band gap range, and may be most efficient at converting light energy of between approximately 980 to 1180 nanometers into electricity. Of course, other photovoltaic cells may be used with the present invention, and such use is within the scope of the present invention. A filter  110  and photovoltaic cell  130  pair in which the filter allows light energy of a range which overlaps or contains some of the wavelengths of light at which the photovoltaic cell is most efficient may be desirable. 
     A first mirror  140  may be located on the outside of the apparatus. The first mirror  140  may be substantially flat, and may be positioned so that light energy striking the first mirror  140  may be substantially reflected onto the filter  110 . The first mirror  140  and the first support  160  may abut one another, forming an angle depicted in  FIG. 1  as γ. The angle γ is preferably in the range of 40 to 50 degrees, and is most preferably substantially 45 degrees. The first mirror  140  may be formed from any material which is substantially reflective of light energy which the photovoltaic cell  130  may absorb and convert into electricity. For example, the first mirror  140  may be formed from a polished metal, or may be formed from a silvered substrate. Alternatively, the first mirror  140  may be partially mirrored, so that the first mirror  140  may absorb one or more wavelengths of light. In this way, the first mirror  140  may absorb some or all of the waste light energy before it is reflected to the filter  110 . 
     A second mirror  120  may be placed within the apparatus, enclosing the photovoltaic cell  130  and forming a triangle with the filter  110 , and may enclose a void  131  therein. The second mirror  120  may be substantially flat, and may be positioned so that light energy passing through the filter  110  from the first mirror  140  may strike the second mirror  120  and be reflected onto the photovoltaic cell  130 . The second mirror  120  and the filter  10  may abut one another. The second mirror  120  and the photovoltaic cell  130  may abut one another, forming an angle depicted in  FIG. 1  as α. The angle a is preferably in the range of 60 to 75 degrees, and is most preferably substantially 67.5 degrees. The second mirror  120  may be formed from any material which is substantially reflective of light energy which the photovoltaic cell  130  may absorb and convert into electricity. For example, the second mirror  120  may be formed from a polished metal, or may be formed from a silvered substrate. Alternatively, the second mirror  120  may be partially mirrored, so that the second mirror  120  absorbs one or more wavelengths of light. In this way, the second mirror  120  may absorb some or all of the waste light energy before it is reflected to the photovoltaic cell  130 . 
     The first support  160  and the second support  150  may be operable to place the first mirror  140  into a position so that the first mirror  140  reflects some or most of the light energy which strikes the first mirror  140  into the filter  110 . The first support  160  and the second support  150  may be formed from a suitable material to support the first mirror  140  and to keep the first mirror  140  substantially in position. The first support  160  and the second support  150  may abut one another, forming an angle depicted in  FIG. 1  as δ. The angle δ is preferably in the range of 60 to 75 degrees, and is most preferably substantially 67.5 degrees. In an alternate embodiment of the present invention, the first support  160  and the second support  150  may be formed singularly. In another alternate embodiment of the present invention, the void  161  created by the union of the first mirror  140 , the first support  160 , and the second support  150  may be occupied, so that the first support  160  and the second support  150  may be formed from a single, solid material onto which the first mirror  140  is positioned. 
     Turning now to  FIG. 1   a,  a side offset view of the photovoltaic cell  130  efficiency improvement device shown in  FIG. 1  is shown according to one embodiment of the present invention. The apparatus may rest on a base  101 , formed from a suitable material to allow for a connection point between the photovoltaic cell  130  and the base  101 , and to substantially maintain the angles α, β, γ, and δ. The base  101  may also be attached to a pivot, so that the base  101  may be positioned in order to reflect a maximum amount of light from the sun or other light producing object. For example, the base may move on the pivot so that the apparatus faces the sun or artificial light source optimally at different times of the day. 
     Turning now to  FIG. 2 , a side view of a photovoltaic cell  130  efficiency improvement device, with exemplary light rays showing operation of the device is shown according to one embodiment of the present invention. First light ray  210  and second light ray  220  may be similar in spectrum, and may include one or more wavelengths of light. First light ray  210  and second light ray  220  are presented for exemplary purposes only, in order to clarify the operation of the apparatus. 
     The first light ray  210  may strike the filter  10 . The filter  110  may be operable to allow certain wavelengths of light energy contained within the first light ray  210  to pass through the filter  110 , and may absorb or reflect the other light energy contained within the first light ray  210 . For example, if the filter  110  is a “1×26” light filter, which allows light energy greater than  760  nanometers to pass, light energy contained within the first light ray  210  with a wavelength greater than 760 nanometers may be allowed to pass through the filter  110 , and light energy contained within the first light ray  210  with a wavelength of approximately less than  760  nanometers may not be allowed to pass through the filter  110 , The light energy not allowed to pass through the filter  110  may be absorbed or reflected by the filter  110 . The light energy contained within the first light ray  210  which is allowed to pass through the filter  110  may become the first filtered light ray  205 . The first filtered light ray  205  may enter the void  131 , and may strike the photovoltaic cell  130 . The photovoltaic cell  130  may utilize some or all of the light energy contained within the first filtered light ray  205  and convert the light energy into electricity. The process of converting light energy into electricity by the use of a photovoltaic cell  130  is well known in the art. 
     The second light ray  220  may strike the first mirror  140 . The first mirror  140  may be operable to reflect substantially all of the light energy contained within the second light ray  220  into the filter  10 . In an alternate embodiment, the first mirror  140  may be operable to absorb some or all of the light energy contained within the second light ray  220 , allowing only certain wavelengths to be reflected into the filter  110 . The second light ray  220  reflected from the first mirror  140  may strike the filter  110 . The filter  110  may be operable to allow certain wavelengths of light energy contained within the second light ray  220  to pass through the filter  110 , and may absorb or reflect the other light energy contained within the second light ray  220 . The light energy contained within the second light ray  220  not allowed to pass through the filter  110  may be absorbed or reflected by the filter  110 . The light energy contained within the second light ray  220  which is allowed to pass through the filter  110  may become the second filtered light ray  207 . The second filtered light ray  207  may enter the void  131 , and may strike the second mirror  120 . The second mirror  120  may be operable to reflect substantially all of the light energy contained within the second filtered light ray  207  into the photovoltaic cell  130 . In an alternate embodiment, the second mirror  120  may be operable to absorb some or all of the light energy contained within the second light ray  220 , allowing only certain wavelengths to be reflected onto the photovoltaic cell  130 . The photovoltaic cell  130  may utilize some or all of the light energy contained within the second filtered light ray  207  and convert the light energy into electricity. The process of converting light energy into electricity by the use of the photovoltaic cell  130  is well known in the art. 
     In this manner, the amount of light energy focused on to the photovoltaic cell  130  may be increased by the use of the first mirror  140  and second mirror  120 , thus allowing a greater amount of light energy to reach the photovoltaic cell  130 . Additionally, the use of the filter  110  may allow more light energy compatible with the band gap of the photovoltaic cell  130  to be focused on to the photovoltaic cell  130 , without also focusing an increased amount of waste light energy onto the photovoltaic cell  130 . 
     The use of one or more dichroic filters in place of the filter and the first mirror may allow for an increased area of photovoltaic cells to be used with the device, and for the photovoltaic cells to receive an increased amount of light energy compatible with the photovoltaic cell&#39;s band gap properties. 
     Turning now to  FIG. 3 , a side view of a dual cell photovoltaic cell efficiency improvement device according to one embodiment of the present invention is shown. One or more dichroic filters may be used to selectively filter light allowed to pass to one or more photovoltaic cells. 
     A first dichroic filter  310  may extend over the first photovoltaic cell  330 , so that, for example, the first dichroic filter  310  may be substantially the same area as the first photovoltaic cell  330 . The first dichroic filter  310  and the first photovoltaic cell  330  may abut one another, forming an angle depicted in  FIG. 3  as ζ. The angle ζ is preferably in the range of 40 to 50 degrees, and is most preferably substantially 45 degrees. The first dichroic filter  310  may be placed at an angle suitable for the transmission characteristics of the filter. The first dichroic filter  310  may be formed from a selectively transparent material, so that light energy striking the filter may be selectively allowed to pass, and selectively reflected by the first dichroic filter  310 . The material may have properties which allow light energy of approximately 980 to 1180 nanometers to pass through the filter, and the filter may reflect light energy of other wavelengths. Of course, other filters having other light selection properties may be used. A first dichroic filter  310  and first photovoltaic cell  330  pair in which light energy having wavelengths overlapping or otherwise matching the first photovoltaic cell efficiency range is allowed to pass through the first dichroic filter  310  is desirable. 
     The first photovoltaic cell  330  may extend underneath the first dichroic filter  310  so that, for example, the first photovoltaic cell  330  is approximately the same area as the first dichroic filter  310 . The first photovoltaic cell  330  may be operable to convert light striking the first photovoltaic cell  330  into electricity. The process by which the first photovoltaic cell  330  converts energy into electricity, and the mechanism that removes electricity out of the first photovoltaic cell  330  and processes the electricity to accomplish work, is well known in the art. With the first dichroic filter  310  described above, filtering substantially all but the  980  to  1180  nanometer range of light energy, one choice for the first photovoltaic cell  330  may be the silicon photovoltaic cell. A silicon photovoltaic cell may have a range of efficiency, and may be most efficient at converting light energy of between approximately 980 and 1180 nanometers into electricity. Of course, other photovoltaic cells may be used with the device, and such use is within the scope of the present invention. A filter and photovoltaic cell pair in which the filter allows light energy of a range which overlaps or contains some of the wavelengths of light at which the photovoltaic cell is most efficient may be desirable. 
     A first mirror  320  is placed within the apparatus, enclosing the first photovoltaic cell  330  and forming a triangle with the first dichroic filter  310 , and enclosing a first void  331  therein. The first mirror  320  may be substantially flat, and may be positioned so that light energy passing through the first dichroic filter  310  and reflected from the second dichroic filter  340  may strike the first mirror  320  and be reflected onto the first photovoltaic cell  330 . The first mirror  320  and the first dichroic filter  310  may abut one another. The first mirror  320  and the first photovoltaic cell  330  may abut one another, forming an angle depicted in  FIG. 3  as ε. The angle ε is preferably in the range of 60 to 75 degrees, and is most preferably substantially 67.5 degrees. The first mirror  320  may be formed from any material which is substantially reflective of light energy which the first photovoltaic cell  330  may absorb and convert into electricity. For example, the first mirror  320  may be formed from a polished metal, or may be formed from a silvered substrate. Alternatively, the first mirror  320  may be partially mirrored, so that the first mirror  320  may absorb one or more wavelengths of light. In this way, the first mirror  320  may absorb some or all of the waste light energy before it is reflected to the first photovoltaic cell  330 . 
     A second dichroic filter  340  may extend over the second photovoltaic cell  360 , so that, for example, the second dichroic filter  340  may be substantially the same area as the second photovoltaic cell  360 . The second dichroic filter  340  and the second photovoltaic cell  360  may abut one another, forming an angle depicted in  FIG. 3  as η. The angle η is preferably in the range of 40 to 50 degrees, and is most preferably substantially 45 degrees. The second dichroic filter  340  may be placed at an angle suitable for the transmission characteristics of the filter. The second dichroic filter  340  may be formed from a selectively transparent material, so that light energy striking the filter may be selectively allowed to pass, and selectively reflected by the second dichroic filter  340 . For example, the second dichroic filter  340  may be formed from a material having properties which allow light of approximately 750 to 950 nanometers to pass through the filter, and the filter may reflect light energy of other wavelengths. Of course, other filters having other light selection properties may be used. A second dichroic filter  340  and second photovoltaic cell  360  pair in which light energy having wavelengths overlapping or otherwise matching the second photovoltaic cell&#39;s efficiency range is allowed to pass through the second dichroic filter  340  may be desirable. 
     The second photovoltaic cell  360  may extend underneath the second dichroic filter  340  so that, for example, the second photovoltaic cell  360  is approximately the same area as the second dichroic filter  340 . The second photovoltaic cell  360  may be operable to convert light striking the second photovoltaic cell  360  into electricity. The process by which the second photovoltaic cell  360  converts energy into electricity, and the mechanism that removes electricity out of the second photovoltaic cell  360  and processes the electricity to accomplish work, is well known in the art. With the second dichroic filter  340  described above, filtering substantially all but the 750-950 nanometer range of light energy, one choice for the second photovoltaic cell  360  is the gallium arsenide photovoltaic cell. A gallium arsenide photovoltaic cell may have a range of efficiency, and may be most efficient at converting light energy of between approximately 750 and 950 nanometers into electricity. Of course, other photovoltaic cells may be used with the device, and such use is within the scope of the present invention. A filter and photovoltaic cell pair in which the filter allows light energy of a range which overlaps or contains some of the wavelengths of light at which the photovoltaic cell is most efficient is desirable. 
     A second mirror  350  may be placed within the apparatus, enclosing the second photovoltaic cell  360  and forming a triangle with the second dichroic filter  340 , and enclosing a second void  331  therein. The second mirror  350  may be substantially flat, and may be positioned so that light energy passing through the second dichroic filter  340  and reflected from the second dichroic filter  340  may strike the second mirror  350  and be reflected onto the second photovoltaic cell  360 . The second mirror  350  and the second dichroic filter  340  may abut one another. The second mirror  350  and the second photovoltaic cell  360  may abut one another, forming an angle depicted in  FIG. 3  as θ. The angle θ is preferably in the range of 60 to 75 degrees, and is most preferably substantially 67.5 degrees. The second mirror  350  may be formed from any material which is substantially reflective of light energy which the second photovoltaic cell  360  may absorb and convert into electricity. For example, the second mirror  350  may be formed from a polished metal, or may be formed from a silvered substrate. Alternatively, the second mirror  350  may be partially mirrored, so that the second mirror  350  may absorb one or more wavelengths of light. In this way, the second mirror  350  may absorb some or all of the waste light energy before it is reflected to the second photovoltaic cell  360 . 
     The first photovoltaic cell  330  and the second photovoltaic cell  360  may be formed from different compositions. For example, the first photovoltaic cell  330  may be formed from a composition where the cell is most efficient at converting light energy of the 980 to 1180 nanometer range into electricity. The second photovoltaic cell  360  may be formed from a composition where the cell is most efficient at converting light energy of the 750 to 950 nanometer range into electricity. Additionally, the first dichroic filter  310  and the second dichroic filter  340  may be comprised of different compositions. A first dichroic filter  310  which transmits a range of light energy partially or substantially overlapping with the band gap range of the first photovoltaic cell  330  may be desirable. A first dichroic filter  310  which reflects a range of light energy partially or substantially overlapping with the range of maximum efficiency of the second photovoltaic cell  360  may also be desirable. A second dichroic filter  340  which transmits a range of light energy partially or substantially overlapping with the band gap range of the second photovoltaic cell  360  may be desirable. A second dichroic filter  340  which reflects a range of light energy partially or substantially overlapping with the range of maximum efficiency of the first photovoltaic cell  330  may also be desirable. In this way, much or substantially all of the light energy striking the first dichroic filter  310  and the second dichroic filter  340 , which partially or substantially overlaps with the range of maximum efficiency of the first photovoltaic cell  330  may be focused onto the first photovoltaic cell  330 . Similarly, much or substantially all of the light energy striking the first dichroic filter  310  and the second dichroic filter  340 , which partially or substantially overlaps with the range of maximum efficiency of the second photovoltaic cell  360  may be focused onto the second photovoltaic cell  360 . 
     Turning now to  FIG. 4 , a side view of a duel cell photovoltaic cell efficiency improvement device, showing exemplary light rays according to one embodiment of the present invention, is shown. First light ray  370  and second light ray  380  may be similar in spectrum, and may include one or more than one wavelengths of light. First light ray  370  and second light ray  380  are presented for exemplary purposes only, in order to clarify the operation of the apparatus. 
     The first light ray  370  may strike the first dichroic filter  310 . The first dichroic filter  3   10  may be operable to allow certain wavelengths of light energy contained within the first light ray  370  to pass through the first dichroic filter  310 , and may absorb or reflect the other light energy contained within the first light ray  370 . For example, if the first dichroic filter  310  is a dichroic filter having a transmission range of 980 to 1180 nanometers, light energy contained within the first light ray  370  with a wavelength of approximately 980 to 1180 nanometers may be allowed to pass through the first dichroic filter  310 , and light energy contained within the first light ray  370  with other wavelengths may not be allowed to pass through the first dichroic filter  310 . The light energy not allowed to pass through the first dichroic filter  310  may be absorbed or reflected by the first dichroic filter  310 . The light energy contained within the first light ray  370  which is allowed to pass through the first dichroic filter  310  may become the first transmitted light ray  372 . The light energy contained within the first light ray  370  which is reflected by the first dichroic filter  310  may become the first reflected light ray  371 . The first transmitted light ray  372  may enter the void  331 , and may strike the first photovoltaic cell  330 . The first photovoltaic cell  330  may utilize some or all of the light energy contained within the first transmitted light ray  372  and convert the light energy into electricity. The process of converting light energy into electricity by the use of a photovoltaic cell is well known in the art. 
     The first reflected light ray  371  may be reflected from the first dichroic filter  310  and may strike the second dichroic filter  340 . The second dichroic filter  340  may be operable to allow certain wavelengths of light energy contained within the first reflected light ray  371  to pass through the second dichroic filter  340 , and may absorb or reflect the other light energy contained within the first reflected light ray  371 . For example, if the second dichroic filter  340  is a dichroic filter having a transmission range of 750 to 950 nanometers, light energy contained within the first reflected light ray  371  with a wavelength of approximately 750 to 950 nanometers may be allowed to pass through the second dichroic filter  340 , and light energy contained within the first reflected light ray  371  with other wavelengths may not be allowed to pass through the second dichroic filter  340 . The light energy not allowed to pass through the second dichroic filter  340  may be absorbed or reflected by the second dichroic filter  340 . The light energy contained within the first reflected light ray  371  which is allowed to pass through the second dichroic filter  340  may become the third transmitted light ray  374 . The light energy contained within the first reflected light ray  371  which is reflected by the second dichroic filter  340  may become the first waste light ray  373 . The third transmitted light ray may enter the void  361 , and may strike the first photovoltaic cell  330 . The first photovoltaic cell  330  may utilize some or all of the light energy contained within the third transmitted light ray  374  and convert the light energy into electricity. The process of converting light energy into electricity by the use of a photovoltaic cell is well known in the art. 
     The second light ray  380  may strike the second dichroic filter  340 . The second dichroic filter  340  may be operable to allow certain wavelengths of light energy contained within the second light ray  380  to pass through the second dichroic filter  340 , and may absorb or reflect the other light energy contained within the second light ray  380 . For example, if the second dichroic filter  340  is a dichroic filter having a transmission range of 750 to 950 nanometers, light energy contained within the second light ray  380  with a wavelength of approximately 750 to 950 nanometers may be allowed to pass through the second dichroic filter  340 , and light energy contained within the second light ray  380  with other wavelengths may not be allowed to pass through the second dichroic filter  340 . The light energy not allowed to pass through the second dichroic filter  340  may be absorbed or reflected by the second dichroic filter  340 . The light energy contained within the second light ray  380  which is allowed to pass through the second dichroic filter  340  may become the second transmitted light ray  382 . The second transmitted light ray  382  may enter the void  331 , and may strike the second photovoltaic cell  360 . The second photovoltaic cell  360  may utilize some or all of the light energy contained within the second transmitted light ray  382  and convert the light energy into electricity. The process of converting light energy into electricity by the use of a photovoltaic cell is well known in the art. 
     The second reflected light ray  381  may be reflected from the second dichroic filter  340  and may strike the first dichroic filter  310 . The first dichroic filter  310  may be operable to allow certain wavelengths of light energy contained within the second reflected light ray  381  to pass through the first dichroic filter  310 , and may absorb or reflect the other light energy contained within the second reflected light ray  381 . For example, if the first dichroic filter  310  is a dichroic filter having a transmission range of 980 to 1180 nanometers, light energy contained within the second reflected light ray  381  with a wavelength of approximately  980  to  1180  nanometers may be allowed to pass through the first dichroic filter  310 , and light energy contained within the second reflected light ray  381  with other wavelengths may not be allowed to pass through the first dichroic filter  310 . The light energy not allowed to pass through the first dichroic filter  310  may be absorbed or reflected by the first dichroic filter  310 . The light energy contained within the second reflected light ray  381  which is allowed to pass through the first dichroic filter  310  may become the fourth transmitted light ray  384 . The light energy contained within the second reflected light ray  381  which is reflected by the first dichroic filter  310  may become the second waste light ray  383 . The fourth transmitted light ray  384  may enter the void  331 , and may strike the second photovoltaic cell  360 . The second photovoltaic cell  360  may utilize some or all of the light energy contained within the fourth transmitted light ray  384  and convert the light energy into electricity. The process of converting light energy into electricity by the use of a photovoltaic cell is well known in the art. 
     The present invention may encourage increased photovoltaic cell efficiency by blocking some waste light from reaching the photovoltaic cell. In this way, overall photovoltaic cell efficiency may be increased, leading to increased use and decreasing overall surface area required to generate the same amount of electricity. This may allow for photovoltaic cells to be used where they may not have been used previously, for example where size or weight requirements would not allow a traditional photovoltaic cell apparatus of appropriate size to generate the electricity needed for a particular task. 
     The embodiments of the present inventions are not to be limited in scope by the specific embodiments described herein. For example, other filters may be used with the apparatus to filter light energy from natural or artificial light. Or, the apparatus may be positioned on a rotating or tilt device so that the apparatus may be positioned ideally with respect to the light source. Or, different photovoltaic cells may be used with the apparatus which may have greater initial efficiency or a different band gap profile. Thus, such modifications are intended to fall within the scope of the following appended claims. Further, although some of the embodiments of the present invention have been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art should recognize that its usefulness is not limited thereto and that the embodiments of the present inventions can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the embodiments of the present inventions as disclosed herein. While the foregoing description includes many details and specificities, it is to be understood that these have been included for purposes of explanation only, and are not to be interpreted as limitations of the invention. Many modifications to the embodiments described above can be made without departing from the spirit and scope of the invention.