Patent Publication Number: US-2011047902-A1

Title: Photovoltaic shingle

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a shingle used for roofing on a building wherein the shingle has a photovoltaic or solar cell for generating electricity such that the shingles of the roof act together to generate electricity for the building. 
     2. Background of the Prior Art 
     Humans depend on oil for a large portion of their energy needs. From powering land vehicles and ocean vessels to being used to fire electricity generating power plants, oil and its various distillates plays a major role in power generation for humans all over the world. However, oil is not without its shortcomings. First of all, oil is a finite resource that may eventually run out. Additionally, as recent events have shown, the price and availability of oil is subject to economic and geopolitical upheaval, causing disruptions in the lives of millions. Additionally, oil is typically considered a “non-green” energy source in that the use of oil generates relatively high pollution amounts. 
     Accordingly, man is trying to move away from oil as a major energy source into renewable and less polluting sources of energy. One such energy source being relied on is solar energy. Solar collector farms are popping up, which farms can generate sufficient electricity to power an entire city. However, such farms tend to be located in relatively desolate and non-forested regions. People living in more densely populated areas or areas with substantial forestation tend to look at smaller solar generation systems. One such smaller system is a single building solar collector system. Such a collector system typically sits atop the roof of the building in a sun facing direction such that solar cells within the system generate electricity whenever the sun shines onto the solar cells. The generated electricity, which is often either 12 or 24 volt DC is channeled into the building&#39;s electrical system either directly or via one or more batteries (in either case passing through an inverter to cover the direct current to 120 volt alternating current (or the current needed at the locale whereat the system resides)) so that during sunny periods, and even some non-sunny periods when batteries are used, the building&#39;s electrical needs are at least partially generated by the solar system so that the building does not need to draw its electricity needs off of the electrical grid. Additionally, many such systems are designed so as to pass any unused electricity generated back onto the power grid so that the building&#39;s occupants “sell back” electricity to the power company. 
     While such solar systems are one step in achieving a reduction in oil use, such systems still have certain shortcomings. Many single building solar systems are comprised of a series of rectangular panels that each hold a multitude of solar cells. Each panel is installed onto the roof and wired in appropriate fashion. One of the problems with such panels is that they are unsightly and many homeowners associations do not allow their use. Additionally, such panels are relatively heavy so that in addition to the costs of installations of the panels proper, the building owner may also need to have the roof structure of the building reinforced to be able to bear the added load created by the panels. 
     To address this problem, devices have been proposed wherein the solar cell is incorporated onto the shingle of the building so as to eliminate the large and rather unsightly collector panels. However, some such shingle systems require a protective glass or similar cover overtop the solar cell (such as crystalline solar cells) so that such cells are relatively thick and inflexible. This cell thickness makes such solar systems practical only for ceramic tile roofs. As many building are impractical for ceramic roofs, either due to aesthetics, strength of the roof, or due to the prohibition in the jurisdiction in which the building is located due to safety concerns from high wind events, such solar systems are impractical to many. Additionally, current systems require an elaborate grid system in order to electrically connect each shingle to the overall electrical system and to the building. Such grids and the labor associated with their installation, make such solar systems impractical for many. Such grids also suffer either partial or even total failure if one of the shingles ceases operation either through damage to the shingle during a storm, for example, or through natural life cycle expiration. 
     What is needed is a solar cell system for typical shingle roofed building that addresses the above mentioned shortcomings found in the art. Specifically, such a system must be relatively thin, flexible, and unobtrusive so as to not adversely impact the aesthetic appeal of the building. Such a system must be relatively straightforward to install without the need for an elaborate grid or substantial involvement of electricians. Such a system must be cost-effective so as to be readily affordable to building owners in the market for such solar systems. 
     SUMMARY OF THE INVENTION 
     The photovoltaic shingle of the present invention addresses the aforementioned needs in the art by providing a shingle based solar cell for installation onto the roof of a building that is relatively thin so as not to detract from the aesthetic qualities of the building onto which the shingle is installed. By being flexible, the present invention is usable as a typical tar-based shingle. The photovoltaic shingle is relatively simple in design and construction so as to be relatively inexpensive to manufacture and purchase. The photovoltaic shingle relies on a very simple electrical grid for transferring the electricity produced from each shingle to the building&#39;s electrical system so that installation costs are kept reasonable. The photovoltaic shingle, when used on a roof, provides a solar system that is highly redundant so that a failure of any shingle in the overall system, is localized to that shingle and does not affect the remainder of the system. 
     The photovoltaic shingle of the present invention is comprised of a shingle body that has a front surface, a back surface, a top, a bottom, a first side, and a second side. A typical tar tab is located on the front surface and extends from the first side to the second side and is positioned between the top and the bottom. An electrically conductive wire grid is disposed on the front surface of the shingle body between the tar tab and the bottom. At least one lead is attached to the back surface of the shingle body above the tar tab such that each lead is electrically connected to the wire grid via connection wires that pass through the shingle body. A solar film is attached to the front surface of the shingle body below the tar tab and either overlays or underlays the wire grid and is electrically coupled to the wire grid such that any electricity generated by the solar film is transferred to the wire grid which in turn transfers the electricity to the leads. The solar film is a thin film solar film. A conduction strip is attached to a typical roof underlayment such that the one or more leads of each shingle are each electrically coupled to the conduction strip when installed on the roof of the building. The conduction strip is electrically coupled to an electrical subsystem which electrical subsystem transfers the electricity onward such as to a building for use therein (either directly or via a battery subsystem) or to an electrical grid. The conduction strip has an adhesive backing for facilitating attachment of the conduction strip to the roof underlayment. A transparent flexible plastic film overlays the solar film in order to protect the solar film. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of the photovoltaic shingle of the present invention 
         FIG. 2  is a side view, sectioned along line  2 - 2  in  FIG. 1 , of the photovoltaic shingle of  FIG. 1 . 
         FIG. 3  is a plan view of the photovoltaic shingle used with a typical three-tab type of roof shingle. 
         FIG. 4  is a side view, sectioned along line  4 - 4  in  FIG. 3 , of the photovoltaic shingle of  FIG. 1 . 
         FIG. 5  is an environmental view of several of the photovoltaic shingles installed on a building. 
     
    
    
     Similar reference numerals refer to similar parts throughout the several views of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, it is seen that the photovoltaic shingle of the present invention, generally denoted by reference numeral  10 , is comprised of a typical tar based shingle body  12  having a front or outward facing surface  14  and a back or building facing surface  16 . A conventional tar tab  18  is located on the front surface  14  of the shingle body  12 . A wire grid  20  is disposed on the front surface  14  of the shingle body such that the wire grid  20  is electrically connected to a series of lead contacts  22  via a series of connection wires  24 . The lead contacts  22  are located on the back surface  16  such that the connection wires  24  pass through the shingle body  12  to contact the leads  22 . The wire grid  20  and the connection wires  24  are made from an appropriate electrical conduction material such as copper. Extending from proximate the bottom of the tar tab  18  and terminating proximate the bottom of the shingle body  12  is a photovoltaic or solar film  26  that overlays and is electrically connected to the wire grid  20  in appropriate fashion, although the solar film  26  may underlay (wire grid  20  on top) the wire grid  20 . The solar film  26  is any appropriate thin film made from thin film solar cell material including cadmium telluride copper indium gallium selenide, amorphous silicon and micromorphous silicon. The shingle body  12  acts as the substrate for the solar film  26 . Although the solar film  26  is typically a large-area, single layer p-n junction diode, the multipoint connection of the wire grid  20  to the output of the solar film  26  allows for redundancy within the shingle  10  should a portion of the shingle  10  fail during use. A transparent flexible plastic film  34  overlays the solar film  26  in order to protect the solar film  26   
     The photovoltaic shingle  10  of the present invention, by being physically similar to a standard tar based roof shingle, is installed in similar fashion to the standard shingle, with the exception of the fact that a conduction strip  28  is positioned onto the roof underlayment (not illustrated) which conduction strip  28  collects the electricity generated by each shingle  10  that is electrically connected to the conduction strip  28  and transfers the electricity to an electrical subsystem  30  of the overall solar system formed, via appropriate wires  32 . The conduction strip  28  may have an adhesive layer so as to be adhesively attached to the roof underlayment. The characteristics of the electrical subsystem  30  are typical of the art for building based solar systems. The subsystem  30  may include batteries and their associated control systems or may be connected directly to the electrical grid via invertors, etc., as is well known in the art. The conduction strip  28  is a flexible member that has sufficient gauge for the amount of electricity generated by the shingles  10 . Each shingle  10  in a given run is attached to the roof so that its lead contacts  22  are electrically coupled to the conduction strip  28 . As each conduction strip  28  is mounted horizontally onto the roof underlayment, all shingles  10  along a horizontal run are disposed in series. If a particular run is of such length that the amperage and/or voltage produced by the shingles  10  is too great, then either some of the shingles on that run may be conventional non-solar shingles or the distal end of the conduction strip  28  is truncated. Each installation is specific to the roof architecture and the type of solar film  26  being used so that all such calculations are performed on site in the usual way. 
     While the invention has been particularly shown and described with reference to an embodiment thereof, it will be appreciated by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention.