Abstract:
A new mounting system for elevating and supporting objects such as solar panels is disclosed. The mounting system is designed for attachment to new or existing roofs of a variety of constructions. Sealing features are incorporated into the mounting system so that additional separate flashing components are not required. The system requires only one bolt for attachment. The design is quick and simple to install, reducing the amount of time and labor required.

Description:
[0001]    This application claims priority benefit of U.S. Provisional Application No. 61/547,860, filed on Oct. 17, 2011, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The present invention relates to mounting system, and more specifically to a roof mounting system for photovoltaic power modules. 
         [0003]    With the high cost of energy, it has become increasingly desirable to provide renewable energy sources for buildings. Photovoltaic modules are often mounted on roof tops to fulfill this need. Roof attachment structures for photovoltaic power systems are an often-overlooked aspect of system design and system cost, but the roof attachment system is in fact one of the most important aspects in terms of liability, e.g., in the event of water leakage or the loss of structural integrity. Additionally, roof attachment is the most labor-intensive step in the installation of a photovoltaic power system, and, therefore, improvements in the ease of attachment will have a great impact on the total life cycle cost of a system. 
         [0004]    With these needs in mind, the present inventors have set out to develop an improved roof mounting system, which will be described below. It is believed that, compared with earlier systems, the structure of the present invention confers several advantages. For example, it is easier to install and less susceptible to water damage. 
         [0005]    U.S. Pat. No. 6,360,491 relates to a roof support system for a solar panel. The mounting base in U.S. Pat. No. 6,360,491 does not provide any sealing features and therefore requires additional separate flashing components. 
         [0006]    U.S. Pat. No. 5,603,187 relates to a watertight system for mounting equipment on roof. The mounting base in U.S. Pat. No. 5,603,187 requires multiple mounting bolts and does not provide any sealing feature, thus requiring additional separate flashing components. 
         [0007]    The Unirac U-RS Series is also typical of the prior art and requires multiple mounting bolts and separate flashing. 
         [0008]    The Zilla Metal Roof Standoff by Next Generation Energy requires separate flashing components. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The present invention is a structure for mounting and supporting objects such as photovoltaic modules on a roof. The mounting system is designed for attachment to new or existing roofs of a variety of constructions. The attachment is via one bolt instead of several thus reducing the number of roof penetrations. Sealing features are incorporated into the mounting system so that additional separate flashing components are not required. The design is quick and simple to install, reducing the amount of time and labor required. 
         [0010]    The novel and unobvious features which are believed to be characteristic of the invention, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a diagram in perspective of the roof mounting standoff illustrating features of the present invention. 
           [0012]      FIG. 2  is another perspective view of the roof mounting standoff showing additional features of the present invention. 
           [0013]      FIG. 3  is a cross section view of the roof mounting standoff mounted in a metal roof construction. 
           [0014]      FIG. 4  is a cross section view of the roof mounting standoff mounted in a wood roof construction. 
           [0015]      FIG. 5  is a perspective view of an embodiment of the present invention for use with a hex socket driver. 
           [0016]      FIG. 6  is a perspective view of an embodiment of the present invention constructed from hex stock. 
           [0017]      FIG. 7  is a perspective view of an embodiment of the present invention for use with an open end wrench. 
           [0018]      FIG. 8  is a perspective view of an embodiment of the present invention for use with a spanner wrench. 
           [0019]      FIG. 9  is a cross-section view of three different cross-sectional embodiments of the present invention. 
           [0020]      FIG. 10  is a view of a roof mounting standoff mounted on a roof. 
           [0021]      FIG. 11  is a perspective view of the roof mounting standoff mounted on a roof. 
           [0022]      FIG. 12  is a photograph of the roof mounting standoff to be mounted in a wood roof construction, said photograph emphasizing the wood screw. 
           [0023]      FIG. 13  is a photograph of the roof mounting standoff to be mounted in a metal roof construction. 
           [0024]      FIG. 14  is a photograph of the roof mounting standoff featuring the top end of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    The present invention is a structure for mounting and supporting objects such as photovoltaic modules on a roof.  FIG. 1  shows one embodiment of such a structure. In  FIG. 1  standoff  1  is comprised of a cylindrical body  2 , threaded bolt  3  engaged with and projecting from cylindrical body  2 , and sealing o-ring seated slot  5 . The bottom of the cylindrical body  2  has a flat surface  4  for mating with the roof surface. In the flat surface  4  is provided a circular grove for housing sealing o-ring  5  and a cavity  6  for housing sealing caulk. As can be seen in  FIG. 2 , on the other end of the cylindrical body  2  is provided flat recesses  7  for engaging a standard open end wrench and a flat surface  8  for supporting objects such as solar panels. In the flat surface  8  is provided a threaded hole  9  for engaging a standard bolt for securing such objects. The cavity or pocket  6  allows for additional sealant material intended as an enhancement and redundance to the sealing capabilities of ‘o-ring seated slot’  5  in the base of  1 . 
         [0026]      FIG. 3  shows a cross section view of standoff  1  mounted on a typical metal roof construction. To mount the standoff  1  a hole is drilled through the metal roofing  11  and into the metal structural member  10 . A readily available standard insert nut  12  is pressed into the structural member  10 . The cavity  6  in the standoff  1  is filled with sealing caulk such as silicon. The threaded bolt  3  portion of the standoff is engaged with the insert nut  12  and threaded in until flat surface  4  mates with the metal roofing  11 . A standard open end wrench engages Flat recesses  7  to tighten standoff  1  securely. The o-ring in the o-ring seated slot  5  is compressed against the metal roofing  11  to provide a positive seal. At the same time the sealing caulk is compressed between the standoff  1  and the metal roofing  11  to provide a secondary means of sealing. No additional separate flashing and sealing components are required. The desired objects can now be secured to the roof with a bolt engaged in threaded hole  9 . An important feature of the standoff  1  is that threaded hole  9  does not connect with the threaded hole  13  provided for engagement with threaded bolt  3 . This material in location  14  prevents migration of water through the inside of the standoff  1  to the roof penetration. 
         [0027]      FIG. 4  shows a cross section view of standoff  15  mounted on a typical wood roof construction. The features of standoff  15  are the same as standoff  1  except that threaded bolt  3  is replaced with wood screw threaded stud  16 . To mount the standoff  15  a pilot hole is drilled through the roofing  18 , plywood sheathing  19  and into the wood structural member  20 . The cavity  6  in the standoff  15  is filled with sealing caulk such as silicon. The wood screw  16  portion of the standoff is threaded into wood structural member  20  until flat surface  4  mates with the roofing  18 . A standard open end wrench engages Flat recesses  17  to tighten standoff  15  securely. The o-ring in the o-ring seated slot  5  is compressed against the roofing  18  to provide a positive seal. At the same time the sealing caulk is compressed between the standoff  15  and the roofing  18  to provide a secondary means of sealing. No additional separate flashing and sealing components are required. The desired objects can now be secured to the roof with a bolt engaged in threaded hole  9 . 
         [0028]      FIG. 5 through 8  illustrates other embodiments of the present invention.  FIG. 5  shows standoff  15  in which the flat recesses  7  of standoff  1  are replaced with a hexagon surface  17  for engaging with a hexagon socket, box end, or open end wrench.  FIG. 6  shows standoff  21  in which the cylindrical body  2  of standoff  1  is replaced with a hexagon body  22 . This eliminates the need to machine separate features for engagement with a wrench or driver.  FIG. 7  shows standoff  23  in which the flat recesses  7  of standoff  1  are located in the middle of the cylindrical body  2 .  FIG. 8  shows standoff  25  in which the flat recesses  7  of standoff  1  are replaced with cylindrical depressions  26  in flat surface  8  for engagement with a spanner wrench. The body of any of the standoffs may be provided in any length to mount the objects at the desired distance from the roof. Further, the flat surface  8  of standoffs  21 ,  23 , and  25  provide a flat sealing surface so that machine screw versions of the standoffs may be mounted on top other standoffs to allow incremental increases in height. 
         [0029]    In the case of composite shingle roofing  29 , such as in  FIG. 10 , or other roofing material that does not present a smooth mounting surface, simple flat sheet flashing  30  can be provided between the roofing surface and the standoff, which is attached to the roof in common best practices. Specialized preformed flashings are not required. In  FIG. 11 , a separate pad  31  to distribute load is shown as an additional embodiment where optional flanges to the post, as described for  FIG. 9 , are not deemed sufficient to provide adequate load distribution to the roof itself. 
         [0030]      FIG. 9  illustrates three different cross-sectional options for the present invention. Standoff  1  is the default cross-section previously described. Standoff  27  is an embodiment of the present invention where a larger flange has been added to either or both the top or bottom surfaces of the standoff  1 . Neither diameter nor thickness of either flange or both flanges is restricted to limit the flange to be larger than the diameter of the body of the standoff nor less than or greater than the total height of the standoff. Either or both flanges can be included or excluded in the embodiment of the standoff as options which might be found to have utility in different applications of the present invention. Standoff  28  is an embodiment of the present invention where the outside diameter of the standoff is reduced at either the top or the bottom of the standoff (functionally a negative flange diameter), as might be found to have utility in different applications. 
         [0031]    The foregoing detailed description is illustrative of a preferred embodiment of the invention, and it is to be understood that additional embodiments thereof will be obvious to those skilled in the art. The embodiments described herein together with those additional embodiments are considered to be within the scope of the invention. 
       Analysis Of Pull Out Strength for the Wood Screw: 
       [0032]    The “withdrawal loads” or “pull out loads” of wood screws inserted into side grain (as opposed to end grain) of seasoned wood is: 
         [0000]        P= 15,700 *Ĝ  2 *D*L*F/M    
       Where: 
       [0000]    
       
         P=pull out strength 
         G=specific gravity of wood 
         D=shank diameter of screw, inches 
         L=length of screw engagement, inches 
         F=adjustment factors such as load duration factor, wet service factor, temperature factor, end grain factor, we use 0.7 here based on M=safety margin of 2.
 
The equation applies to screw pilot holes diameter=&lt;70% of thread root diameter for softwood. Specific gravity is based on ovendry at 12% moisture content.
 
       
     
         [0038]    As an example of the above, for a 0.25″ wood screw threaded into fir. the G=0.31 (lowest of all varieties). The pull out strength per inch of screw engagement P=132 pounds per inch of screw engagement. 
       Analysis of Pull Out Strength for a Metal Roof: 
       [0039]    The pull-out strength of the screw connection is highly depending on the design of the “riv-nut” insert and the metal structure the riv-nut it attaches to. In most cases you can make it work by adjusting the following features:
   1. Use a larger riv-nut to spread the tear-out load on the metal member.   2. Use a riv-nut with a stronger material.   3. Use a riv-nut with a longer thread length.   
 
         [0043]    If the proper riv-nut is selected, the weakest link in the fastening system is on the metal structural member. In that case the pull out strength P would be: 
         [0000]        P= 0.6 *S*PI*D*T*F/M    
       Where: 
       [0000]    
       
         P=pull out load 
         S=ultimate tensile strength of metal member PI=pi or 3.14 D=flange diameter of riv-nut T=thickness of metal member F=adjustment factor, use 0.7 here M=factor of safety, use 2 here 
       
     
         [0046]    For example, if S=50,000 psi for mild steel, D=0.5″, T=0.06″. Then, P=990 pounds, which is much lower than the 0.25 stainless fastener used in this example but still much better than a same size wood screw threading into wood beams. 
       EXAMPLES 
     Static Testing 
       [0047]    A significant enhancement to the technology of post-roof interfacing is achieved through the use of an o-ring in the device. The o-ring provides an effective water seal at the interface without the use of additional caulking or sealing. 
         [0048]    The integrity of the o-ring seal against leakage was tested by using a post for mounting a panel and by attaching the post of the invention to the bottom of a galvanized steel basin, simulating attachment to a metal roof for to metal flashing. No other sealing methods were employed. The basin was then filled with water to a depth of approximately one foot. This provides a constant pressure of about 0.4 psi across the surface. Since no other sealing method is used (e.g., using silicone, grease or wax), there is no non-polar electrostatic resistance or glue barrier to capillary intrusion by water into the joint. Only joint pressure applied on the o-ring will resist water intrusion. After several months in this condition, the assembly showed no signs of leakage. 
       Dynamic Testing 
       [0049]    To test post-roof joint integrity under dynamic conditions, two posts were installed in tandem in a galvanized basin and fastened through into a wood joist to simulate a wood-framed roof. The posts were sealed at the basin interface as recommended for permanent installations using both the o-ring and a fillet of silicone caulking. The basin was then filled with water. The posts were connected at the top with a joist, and through a moment arm attached to a motor-driven cam, the assembly was set to rock in a periodic motion at about 40 cycles/minute. This tests four failure points simultaneously: pullout of the fastening into the roof, pullout of the fastening in the post, seal against leakage at the interface, and resistance to leakage or failure due to flexing or distortion of the roof surface. 
         [0050]    The set up has completed over 500,000 cycles with no interface or leakage failure. It should be noted that the cross-braces which were nominally attached to each side of the wood joist have worked loose, but the joist itself, bolted through the basin into the posts, has not. While this was not a principal point of testing, it might be inferred that continuous stresses on a roof transmitted through the post system of the invention may cause the roof structure to fail before the post interface will fail. 
         [0051]    It is to be understood that both of the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed.