Imported: 10 Mar '17 | Published: 27 Nov '08
USPTO - Utility Patents
A roofing module provides weather protection generates electrical power. The module includes an injection molded base having a size, a shape and an appearance of a conventional flat concrete roofing tile with a top surface having a slate-like striated texture. The base is made from lightweight plastic material. The base includes a depressed portion in an upper surface. A photovoltaic panel assembly is positioned in the depressed portion with electrical conductors from the photovoltaic panel passing through an opening in the depressed portion.
The present application claims the benefit of priority under 35 U.S.C. 119(e) to U.S. Provisional Application No. 60/940,408, filed on May 26, 2007.
1. Field of the Invention
The present invention relates to solar panels for generating electrical energy and more particularly relates to solar modules integrated into a flat roof tile.
2. Description of the Related Art
Conventional solar panels for generating electrical power for residences are flat and are placed on a portion of the roof that faces the sun during midday. Originally, the solar panels were mounted over existing roofing materials (e.g., shingles) and formed a generally unaesthetic addition to a home. In some areas, the solar panels were not permitted because of the unattractive appearance. Recently developed solar panels are constructed in sizes and shapes that can be mounted directly to the underlying roof structure as replacements for flat roofing materials (e.g., flat concrete tiles) such that the solar panels provide the dual purpose of generating electrical power in response to sunlight and of providing protection from moisture intrusion while integrating in an aesthetically pleasing way with the roof system.
The roofing tile with integrated modular solar panel described herein and illustrated in the attached drawings enables the electricity-generating solar panel to be included in a seamless application with a conventional roofing tile because the solar panel is advantageously embodied in a shape and size of a conventional flat tile. As discussed herein, the size and shape of the solar panel tile may be adapted to the size and shape of tiles from a number of different manufacturers. The size and shape of the solar panel tile enables the same roofing mechanic who installs the conventional roofing tiles to install the solar panel tile without any special tools or fasteners. In particular, the solar panel tiles interlock with or overlap with adjacent conventional tiles when installed in the same course. The adjacent tiles may be solar panel tiles or conventional roofing tiles. The solar panel tiles have aesthetic features that match the aesthetic features of the conventional tiles.
FIGS. 1-7 illustrate an embodiment of a flat solar panel tile 100 suitable for mass production using injection molding techniques. The solar panel tile 100 comprises a tile base 102 and a solar panel assembly 104. The solar panel assembly comprises a solar panel support frame 106 and a photovoltaic panel (solar cell array) 108.
The tile base 102 is sized and shaped to conform to the size and shape of a conventional flat concrete tile configured to simulate the aesthetic appearance of a slate tile. In particular, the tile base has a plurality of striations (e.g., closely spaced grooves and ridges) formed on an exposed top surface 112 that are similar to the grooves on a concrete tile so that the top surface provides a slate-like appearance when viewed from a distance. An opposing bottom surface 114 (FIG. 2) of the tile base is formed as a plurality of strengthening ribs 116. Preferably, the tile base comprises injected molded plastic.
In the following description, top and bottom are used to designate the two opposing surfaces 112, 114 with respect to the thickness of the solar panel tile 100; upper and lower and height refer to the aspects of the tile with respect to a vertical direction along the slope of a roof (not shown) when a solar panel tile is oriented in a typical roof installation; and left and right and width refer to aspects of the tile with respect to a horizontal direction across the roof.
The top surface 112 of the tile base 102 has a horizontal width of approximately 34.6 inches and has a height of approximately 17 inches. In the illustrated embodiment, the tile base has an overall thickness from the top surface to the bottom surface 114 of approximately 1.25 inches. In general, the plastic is molded to have a structural thickness of approximately 0.125 inches in most locations; however, the plastic may be thicker in some portions of the structure and thinner in other portions of the structure in accordance with the mold characteristics.
The solar panel tile 100 is positioned in FIG. 1 with an upper edge 120 of the tile base 102 located toward the lower left in the drawing and with a lower edge 122 located toward the upper right in the drawing. The tile base is configured to be positioned on a roof in a horizontal rank with the upper edge of the tile base positioned beneath a lower edge of a tile in a next higher rank such that the tiles in higher ranks overlap tiles in the next lower rank in a conventional manner. The top surface of the tile base includes a plurality of holes 124 (e.g., 6 holes) formed approximately 1.8 inches from upper edge and extending through the thickness of the tile base. Each hole has a diameter of approximately 0.078 inch. When the solar panel tile is installed on a roof, a fastener may be driven through the holes to secure the tile to the roof. The holes are covered by an overlapping portion of a tile in a higher rank on the roof.
The top surface 112 of the tile base 102 has a left edge 130 shown at the lower right for the orientation of the tile base in FIG. 1. The tile base includes a lower interlocking tab 132 that extends outwardly from the left edge by approximately 1 inch. An interlocking groove 134 is formed in the tab parallel to the left edge.
The top surface 112 of the tile base 102 has a right edge 140 shown at the upper left in the orientation of the tile base in FIG. 1. An interlocking tongue 142 extends downwardly below the top surface proximate to the right edge. The tongue is sized and positioned so that the tongue engages the interlocking groove 134 when the right edge of the tile base is placed adjacent to the left edge of a tile in the same horizontal rank. Thus, two horizontally adjacent tiles are interlocked. In addition, any water draining into the space between the left and right edges of adjacent tiles is drained by the groove to the top surface of a tile in the next lower rank.
As shown in FIGS. 3 and 4, the top surface 112 of the tile base 102 has a recessed portion 150. The recessed portion has a generally rectangular shape having a width from left to right of approximately 32.3 inches. The recessed portion has a height in the direction from the upper edge of the tile base toward the lower edge of the base tile of approximately 12.4 inches. The boundaries of the recessed portion are defined by four perimeter walls. An upper boundary wall 152 is offset from the upper edge 120 of the tile base by approximately 4.2 inches. A lower boundary wall 154 is offset from the lower edge 122 of the tile base by approximately 0.5 inch. A left boundary wall 156 is offset from the left edge 130 of the base tile by approximately 1 inch. A right boundary wall 158 is offset from the right edge 140 of the tile base by approximately 1.3 inches. The recessed portion has bottom surface 160 at a depth from the top surface of approximately 0.55 inch.
As further shown in FIGS. 2, 3 and 4, the recessed portion 150 includes a generally rectangular cutout 170. The cutout passes through the tile base 102 from the bottom surface 160 of the recessed portion to the bottom surface 114 of the tile base. The ribs 116 of on the bottom surface of the tile base are removed in the area encompassed by the cutout. In the illustrated embodiment, the cutout has a width in the direction from the left boundary towards the right boundary of approximately 4-4.25 inches, and has a length in the direction from the upper boundary of the recess to the lower boundary of the recess of approximately 2.5-2.75 inches. The cutout is offset from the right boundary wall 158 of the recess by approximately 0.5-0.75 inch. The cutout is positioned approximately midway between the upper boundary wall 152 and the lower boundary wall 154. The cutout may also be located elsewhere in the recess in accordance with the positioning of electrical connectors (discussed below) on the photovoltaic panel 108.
As further illustrated in FIGS. 3 and 4, the cutout 170 is surrounded by a perimeter ridge 172 that has a thickness of approximately 0.1 inch and that is raised above the bottom surface 160 of the recessed portion 150 by approximately 0.25 inch. Any water that may collect on the bottom surface of the recessed portion is blocked from flowing into the cutout by the perimeter ridge. The lower boundary wall 154 of the recessed portion includes a plurality (e.g., 3) of slots 174 that pass through the upper surface 112 of the tile base 102 to permit any such water to drain onto the top surface of a tile in the next lower rank of tiles or to drain from the roof if the tile is in the lowest rank.
As shown in FIG. 3, the lower boundary wall 154 of the recessed portion 150 further includes a plurality of rectangular openings 180 (e.g., 3 openings) having widths of approximately 1 inch and having heights of approximately 0.375 inch. As shown in FIG. 4, the upper boundary 152 includes a plurality (e.g., 3) of generally circular openings 182 having diameters of approximately 0.156 inch.
The recessed portion 150 of the tile base 102 is sized and shaped to receive the solar panel support frame 106. The support frame comprises an injection molded plastic material with an upper outer wall 202, a lower outer wall 204, a left outer wall 206 and a right outer wall 208 that conform to the upper boundary wall 152, the lower boundary wall 154, the left boundary wall 156 and the right boundary wall 158 of the recessed portion. Each outer wall of the support frame has a height of approximately 0.5 inch, which is slightly less than the depth of the recessed portion so that when the support frame is positioned within the recessed portion, the top of each outer wall is generally flush with or slightly below the upper surface 112 of the tile base 102. The rectangular outer dimensions of the support frame are slightly smaller than the rectangular dimensions of the recessed portion of the tile base so that the support frame fits easily in the recessed portion with little room for movement in any direction.
The support frame 106 includes a plurality of generally rectangular protrusions 210 (e.g., 3 protrusions) extending from the lower outer wall 204. The protrusions are positioned to be aligned with and inserted into the rectangular openings 180 in the lower boundary wall 154 of the recessed portion 150 of the tile base 102. The support frame further includes a plurality of circular openings 212 (e.g., 3 openings) extending partially through the upper outer wall 202 below the level of the recessed portion. When the support frame is inserted into the recessed portion of the tile base, the circular openings in the support frame are aligned with the circular openings 182 in the upper boundary wall 152 of the recessed portion. As shown in FIG. 2 and in FIG. 6, a fastener (e.g., a screw) 214 is inserted through the aligned holes to secure the support frame to the tile base.
The support frame 106 has a recessed middle portion 220 that has a depth of approximately 0.1875 inch to a lower surface 222 of the recessed middle portion. Each outer wall of the support frame 106 has a thickness of approximately 0.25 inch. The recessed middle portion of the support frame has a vertical length in the direction from the inside of the lower outer wall 204 to the inside of the upper outer wall 202 of approximately 12.31 inches and has a horizontal width in the direction from the inside of the left outer wall 206 to the inside of the right outer wall 208 of approximately 31.7 inches.
In the illustrated embodiment, the lower surface 222 of the recessed middle portion 220 of the support frame 106 has a plurality of openings 230 (e.g., 19 openings) formed therein to reduce the mass of the support frame, which also reduces the quantity of plastic needed to manufacture the support frame. Sixteen of the openings are formed in a pattern of rectangular openings with the sides having longer lengths parallel to the left outer wall 206 and the right outer wall 208 and with sides having shorter lengths parallel to the upper outer wall 202 and the lower outer wall 204. Although illustrated as rectangular openings, the openings may be configured in other shapes. Three of the openings proximate the right outer wall are positioned with the respective longer sides parallel to the upper outer wall and the lower outer wall. One of the three openings is designated as a connector module opening 232. The connector module opening aligned with and has approximately the same dimensions as the outer dimensions of the perimeter ridge 172 surrounding the cutout 170 in the recessed portion 150 of the tile base 102. The size and position of the connector module opening are also selected to match the position of the positioning of electrical connectors (discussed below) on the photovoltaic panel 108. As illustrated in the bottom view in FIG. 5, the rectangular openings are surrounded by a plurality of ribs 234 extending horizontally and vertically across the support frame to provide a structurally stable frame.
The recessed middle portion 220 of the support frame 106 is sized to receive the photovoltaic (solar cell array) panel 108. The photovoltaic panel has a generally rectangular surface having a horizontal width of approximately 31.65 inches, a vertical height of approximately 11.75 inches and a thickness of approximately 0.1875 inch between an upper surface 304 and a lower surface 306. The photovoltaic panel may have a conventional construction comprising a plurality of cells connected in a selected series-parallel combination to produce a desired output voltage when solar energy is incident on the upper surface of the photovoltaic panel. In a particularly preferred embodiment, the photovoltaic panel is constructed in the manner described in FIGS. 8, 9 and 10, described below. The photovoltaic panel is secured in the support frame by a suitable weather-resistant adhesive, such as, for example, silicon adhesive.
The lower surface 306 of the photovoltaic panel 108 includes an output module (junction box) 310, which is adhered to the lower surface after the photovoltaic panel is constructed in the manner described in FIGS. 8, 9 and 10. In particular, first and second sturdy weather-resistant, external electrical conductors 312, 314 are electrically connected to the relatively fragile electrical conductors (not shown) that provide the electrical output of the cells in the photovoltaic panel.
After the electrical interconnections are completed and tested, the output module (junction box) 310 is adhered to the lower surface 306 of the photovoltaic panel 108 in a conventional manner using epoxy sealant (see FIG. 6). The output module provides electrical insulation over the electrical connections and that also provides strain relief so that handling of the external electrical conductors 312, 314 during installation of the flat solar tile 100 does not break the electrical connections or break the fragile electrical conductors of the photovoltaic panel 108. Preferably, the output module is formed using a mold (not shown) so that the output module has predetermined dimensions (e.g., rectangular) that fit within the cutout 170 in the tile base 102 and that pass through the opening 232 in the support frame 106. For example, in the illustrated embodiment, the output module has a horizontal length of approximately 4.2-4.4 inches, a vertical width of approximately 2.6-2.7 inches and a thickness of approximately 0.3 inch.
When the photovoltaic panel 108 is inserted in the support frame 106 and the support panel is inserted in the tile base 102, the output module fits within the aligned opening 232 in the support frame and the cutout 170 in the tile base. The external conductors 312, 314 extend below the tile base. As illustrated in FIG. 5, the tile base includes a plurality of rib notches 320 formed in selected ones of the ribs 116 proximate the upper edge 120. The rib notches are sized to receive the external conductors. One of the external conductors (e.g., the first conductor 312) is routed through a first set of the rib notches and through a first edge notch 322 in the upper edge 120 of the tile base proximate the left edge 130. The other external conductor (e.g., the second conductor 314) is routed through a second set of the rib notches and through a second edge notch 324 in the upper edge proximate the right edge 140.
A selected length of the first conductor 312 extends beyond the first edge notch 322 and is terminated in a first weather resistant connector 330 having a first mating polarity (e.g., female). A selected length of the second conductor 314 extends beyond the second edge notch 324 and is terminated in a second weather resistant connector 332 having a second mating polarity (e.g., male). When a plurality of the solar tiles 100 are positioned in a horizontal rank on a roof, the photovoltaic panels 108 in adjacent solar tiles are electrically connected in series by plugging the male connector from one tile into the female connector of the adjacent tile. The tile at each end of a horizontal rank of tiles is connected to a respective cable connected to a control system (not shown) in a central location that receives the electrical outputs from the strings and provides a system power output in a conventional manner.
As discussed above, the photovoltaic panel 108 may be a conventional photovoltaic panel configured to have the dimensions described above. In preferred embodiments, the photovoltaic panel is constructed in accordance with a laminated photovoltaic panel 600 illustrated in FIGS. 8, 9 and 10. The photovoltaic panel 600 is configured as a generally rectangular panel, which is sized and shaped to fit in the depressed central portion 220 of the support frame 106.
As illustrated in FIGS. 8, 9 and 10, a laminated photovoltaic panel 600 is configured as a generally rectangular panel, which is sized and shaped to fit in the depressed central portion 220 of the support frame 106. In the illustrated embodiment, the panel 600 has dimensions of approximately and has a thickness of less than approximately 0.2 inch to fit within the depth of the depressed central portion.
The panel 600 has a transparent upper protective layer 610 that faces upward and is exposed to the sun. A middle layer 620 is positioned beneath the upper protective layer 610. The middle layer 620 comprises a plurality of photovoltaic cells 622 that are electrically interconnected. The middle layer 620 rests on a rigid lower layer 630. The middle layer 620 is secured to the rigid lower layer 630 by a lower adhesive layer 640. The middle layer 620 is secured to the upper protective layer 610 by an upper adhesive layer 650.
The upper protective layer 610 provides impact protection as well as weather protection to the panel 600. The upper protective layer 610 advantageously comprises DuPont Teflon fluorinated ethylene propylene (FEP) resin, which is formed into a film layer of suitable thickness (e.g., approximately 0.1 inch). Thus, the photovoltaic cells 622 in the middle layer 620 are exposed to direct sunlight without being exposed to moisture and other climatic conditions and without being exposed to direct impact by feet, falling objects, and debris.
In the illustrated embodiment, the rigid lower layer 630 comprises fiber reinforced plastic (FRP). For example, the FRP layer advantageously comprises a polyester resin with embedded stranded glass fibers. In one advantageous embodiment, the FRP layer has a thickness of approximately 0.079 inch. The rigid lower layer of FRP provides an advantageous combination of light weight, rigidity, very low permeability and flatness
Preferably, the lower adhesive layer 640 is provided as a thin film that is positioned on the upper surface of the rigid lower layer 630. The array of photovoltaic cells 622 in the middle layer 620 is then positioned on the lower adhesive layer 640. In the illustrated embodiment, the lower adhesive layer 640 advantageously comprises a transparent adhesive, such as, for example, ethylene-vinyl-acetate (EVA). EVA is a transparent, heat-activated adhesive that is particularly suitable for securing the cells. Other suitable adhesives, such as, for example, polyvinylbuterol (PVB), or other pottant materials, can be substituted for the EVA. before positioning the photovoltaic cells 640 on the lower adhesive layer 640.
After positioning the array of photovoltaic cells 622 on the lower adhesive layer 640, the upper transparent adhesive layer 650 is placed over the middle layer 620 so that the photovoltaic cells 622 are sandwiched between the two transparent adhesive layers. The upper adhesive layer 650 should match the physical characteristics of the lower adhesive layer 640. In the illustrated embodiment, both the upper adhesive layer 650 and the lower adhesive layer 640 comprise EVA, but other suitable transparent adhesives can be substituted for the EVA. The transparent upper protective layer 610 is then positioned over the upper transparent adhesive layer 650 to complete the laminated structure shown in an enlarged partial cross section in FIG. 9.
The EVA material and the use of the EVA material to bind the layers of a laminated photovoltaic cell are described, for example, in U.S. Pat. No. 4,499,658 to Lewis. In addition to acting as a binder to secure the photovoltaic cells 622 between the upper protective layer 610 and the lower rigid layer 630, the upper EVA layer 650 and the lower EVA layer 640 also act as a cushion between the two outer layers.
The photovoltaic cells 622 are electrically interconnected in a series-parallel configuration in a conventional manner to provide a suitable output voltage. For example, in the illustrated embodiment, 12 photovoltaic cells 622 are arranged in 2 rows of 6 cells each. The photovoltaic panel 600 is illustrated with two flat ribbon electrical conductors 660, 662 extending from right side of the middle layer 620. The two conductors 660, 662 are electrically connected to the external conductors 312, 314 within the connector module 310 shown in FIGS. 1-7. In the illustrated embodiment, the two electrical conductors 660, 662 are bent and are passed through openings (not shown) in the rigid lower layer 630. Thus, the free ends of the two conductors 660, 662 are exposed beneath the rigid lower layer 630 for interconnection to the external conductors 312, 314 within the connector module 310, as described above.
The upper protective layer 610, the middle layer 620, the lower layer 660, and the two adhesive layers 640 and 650 are stacked in the order shown in FIGS. 9 and 10 and are aligned to form the sandwich structure shown in FIGS. 8 and 9. The free end of each of the two panel output conductors 660, 662 are covered with a temporary covering (e.g., a cloth tube, or the like) during the lamination process. The structure is permanently laminated in a known manner using heat and pressure. In one advantageous embodiment, the structure is laminated in a vacuum laminator in the manner described, for example, in US Patent Application Publication No. 2005/0178248 A1 to Laaly et al. In particular, the structure is first subjected to a vacuum to remove any trapped gas bubbles in the EVA adhesives. The structure is then subjected to high pressure to force the layers together as tightly as practical. The structure is then heated to a suitable temperature (e.g., approximately 160 C.) to cure the adhesives in the layers 640 and 650 and thereby permanently bond the adjacent layers. During the high temperature portion of the process, a portion of the upper layer 610 softens sufficiently to form a coating that surrounds the outer edges of the other layers, thus forming a moisture-resistant coating around the entire structure. In the illustrated embodiment, the upper layer 610 and the two transparent adhesive layers 640, 650 secure the panel output conductors 660, 662 to the top of the middle layer 620. Preferably, the panel output conductors 660, 662 extend from the bottom of the middle layer 620 and pass through one or more openings (not shown) in the rigid lower layer 630. The opening through the bottom layer 630 is sealed during the lamination process. In an alternative embodiment, the panel output conductors 660, 662 are connected to the photovoltaic cells 622 on the middle layer 620 after the lamination process is completed using known interconnection techniques.
The laminated structure is held at the high temperature for a sufficient time to cure the upper transparent adhesive layer 650 and the lower transparent adhesive layer 640 and to cause the two transparent adhesive layers to adhere together to become a combined layer that completely encapsulates the photovoltaic cells 622. The high temperature also causes the upper transparent layer 610 to soften and flow to provide the protective upper coating described above. The laminated structure is then allowed to cool to ambient temperature.
After the lamination process is completed, the two panel ribbon conductors 660, 662 are connected to the two external conductors 312, 314, as discussed above. The connections between the conductors and a portion of the conductors are connected within the output module 310, as further discussed above. The panel is secured to the panel support frame 106, and the panel support frame is secured to the tile base 102 to complete the assembly of the complete flat solar tile 100.
In accordance with the embodiments disclosed herein, an aesthetically flat solar tile 100 combines the weather protection features and appearance of a conventional flat concrete slate tile with the electrical energy generating capabilities of a solar cell sandwich. The flat solar tile is easily installed with flat concrete tiles to include electrical energy generation capability on newly constructed roofs and can replace concrete tiles to add electrical energy generation capability to existing roofs.
The present invention is disclosed herein in terms of a preferred embodiment thereof, which provides a photovoltaic panel integrated into a flat solar tile having the appearance of a concrete slate tile, as defined in the appended claims. Various changes, modifications, and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope of the appended claims. It is intended that the present invention encompass such changes and modifications.