Abstract:
A photovoltaic (PV) mounting system having a base portion with a plurality of rails. The system includes a spring clip unit having a foot configured to hold a PV module coupling device and arranged to slide on one of the plurality of rails. A first spring clip is moveable on the foot from a first position in which the first spring clip is disengaged with the rail to allow the foot to move freely along the rail, to a second position in which the first spring clip engages the rail to attach the foot to the rail. A second spring clip is held by the foot and is forcibly engaged with the rail when the first spring clip is moved to the second position to help lock the foot.

Description:
BACKGROUND OF THE INVENTION 
     There are many systems available for mounting photovoltaic (PV) modules to building structures, such as a roof. These systems serve as a rigid interconnection element between a roof and a PV module to hold the modules in place and resist the forces of gravity and wind. 
     Traditionally, mounting systems consisted of rows of rail structures attached to the roof in columns or rows. Module clamps were used to attach the PV modules to these rail structures. Although effective, these traditional systems required complex and time-consuming installations and utilized relatively large amount of materials. Eventually, pioneers in the solar industry, such as Jack West of San Rafael-based Zep Solar, realized that module frames themselves are sufficiently rigid to function as the rails of a PV mounting system. By utilizing the inherent rigidity of modules frames as part of the PV mounting system, system part counts and costs of PV mounting systems were significantly reduced while installation time and overall aesthetics were improved. This realization caused the majority of the residential solar industry to move away from rail-based solutions. However, in order to continue the momentum of solar against other fossil fuel-based energy sources, it is imperative that both hard and soft PV costs continue to be reduced. 
     Most rail-free or so-called direct mount systems, rely on pillar-like PV module supports which connect to each module frame at various points around the array—typically at least four points on each module. These module supports are in turn attached to the roof, either into a roof rafter or directly to the roof deck, via a flashing. The flashing is just a flat sheet of aluminum with a preformed feature designed to mate with the module support and typically including at least one lag-bolt through-hole for securing both the flashing and the module support to the roof. 
     Although effective at reducing water leaks and covering missed drill holes, flashings can increase the time of installation because when they are used, the installer must complete all site preparation first before placing any of the PV modules, installing a flashing at each intended roof penetration. This bottleneck prevents an installer from installing the array row-by-row or panel-by-panel and, as a result, may slow-down the rate at which PV may be installed, may require larger installation crews, or both. Also, because each flashing gets tucked underneath the next up-roof course of shingles, it is often necessary to remove existing roofing nails to accommodate the flashings. Each time an existing roofing nail is removed, a new potential leak point is created. Finally, each flashing adds a material cost to each solar installation that becomes significant when multiplied against every roof penetration of every installed array. 
     Accordingly, there is a need for a rail-free PV mounting system that enjoys the benefits of existing rail-free solutions, while reducing costs, and increasing installation times relative to such systems. 
     BRIEF SUMMARY OF THE INVENTION 
     Many embodiments of the invention are directed to a photovoltaic (PV) mounting system having a base portion with at least one rail. The system can include at least one spring clip unit having a foot configured to hold a PV module coupling device and arranged to slide on one of the plurality of rails. A first spring clip may be moveable on the foot from a first position, in which the first spring clip is disengaged with the at least one rail to allow the foot to move freely along the at least one rail, to a second position, in which the first spring clip engages the rail to laterally lock the foot to the at least one rail. The foot can hold a second spring clip. The second spring clip may be forcibly engaged with the at least one rail to vertically lock the foot to the at least one rail. 
     In many embodiments, each rail of the plurality of rails can include a pair of channels that the foot slides within. 
     In many embodiments, the first spring clip can include an elongated lever extending to a first tab and a second tab. 
     In many embodiments, the first tab and a second tab can each be arranged to pass through the foot and engage the base when the lever is actuated to the second position of the first spring clip. 
     In many embodiments, the first tab and a second tab may be each arranged to disengage from the base when the lever is actuated to the first position of the first spring clip. 
     In many embodiments, the second spring clip can include teeth arranged to forcibly engage the at least one rail and form a ground connection between the foot and the at least one rail. 
     Many embodiments of the invention are directed to a photovoltaic mounting system (PV) with a base portion having a plurality of raised rail portions, with each raised rail portion having a pair of channels on either side of the rail portion. The base portion can further include a through-hole for accommodating a roof surface attachment bolt. At least one spring clip unit may be provided with the system. The at least one spring clip unit can include a first lever-actuated spring clip that in a first position allows the at least one spring clip unit to fit over and move freely on one of the raised rail portions, and that in a second position causes a pair of tabs connected to the lever-actuated spring clip to engage the pair of channels in the raised rail portion. A second spring clip can engage the top of one of the raised rail portions, and include one or more teeth that form a ground bond with the raised rail portion when the first lever-actuated spring clip is moved into the second position. A PV module coupling device attached to the at least one spring clip unit may be provided and may be adapted to engage the frames of at least two PV modules while maintaining a space in between them. 
     In many embodiments, the first lever-actuated spring clip can include an elongated lever extending to a pair of corner portions that narrow and widen with respect to each other according to positioning of the first lever-actuated spring clip. 
     In many embodiments, the pair of tabs can narrow and widen along with corresponding movement of the corner portions. 
     In many embodiments, the first lever-actuated spring clip may be a wire-form structure. 
     In many embodiments, the second spring clip may be formed as at least one body that extends in cantilever from the at least one spring clip unit. 
     In many embodiments, the teeth are formed at a free end of the at least one body. 
     In many embodiments, the PV module coupling device has an upper and lower clamp arranged to clamp onto top and bottom portions of a PV module 
     In many embodiments, each raised rail portion has a male shape. 
     In many embodiments, the at least one spring clip unit has a female shape that is complimentary to the male shape. 
     Many embodiments are also directed to a PV mounting system having a base portion with at least one rail. The system can include at least one spring clip unit configured to hold a PV module coupling device and comprising at least one lever to lock the at least one spring clip unit to the at least one rail. 
     In many embodiments, the at least one lever may be movable to unlock the at least one spring clip unit from the at least one rail. 
     In many embodiments, a first movement of the at least one lever can cause tabs of the least one spring clip unit to narrow and engage the at least one rail. 
     In many embodiments, a second movement of the at least one lever that is opposite to the first movement can cause the tabs of the least one spring clip unit to forcibly spread apart from the at least one rail. 
     In many embodiments, the at least one spring clip unit can include a plurality of levers. 
     In many embodiments, the at least one spring clip unit can have teeth for engaging the at least one rail. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a perspective view of an exemplary PV mounting system, according to an embodiment of the invention. 
         FIG. 1B  shows a perspective view of an aspect of the system of  FIG. 1A . 
         FIGS. 2A-2D  show operational views of an aspect of the system of  FIG. 1A . 
         FIG. 3  shows a perspective view of another exemplary PV mounting system, according to an embodiment of the invention. 
         FIG. 4  show the system of  FIG. 1A  in use, according to an embodiment of the invention. 
         FIG. 5  shows a perspective view of another exemplary PV mounting system, according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention are generally directed towards a system for mounting a PV panel to a support structure such as a roof surface. The system can include a base portion assembly and a foot assembly for supporting a PV panel. The foot assembly may include a spring clip unit that when actuated from a first position to a second position with the base portion assembly, provides a boltless system for rigidly fixing the foot assembly to the base portion assembly in a sufficient manner to support the weight of one or more PV panels. Advantageously, such a system requires little to no tools for installation, and hence installation time is greatly reduced over prior systems that require additional tools and bolting. The following description details some examples of such a system. 
       FIG. 1A  shows a system  100  for mounting a photovoltaic (PV) panel to a structure, such as a roof. The system  100  includes a base portion  102  having a plurality of raised portions, depicted here as rails  104 . Here, three rails  104  are shown, although more or less may be provided. Base portion  102  also includes passage  105  for mounting base portion  102  to a roof with a mechanical fastener, such as a lag bolt. 
     Base portion  102  is generally planer in shape with lateral edges  106  that raise base portion  102  above a mounting surface to help with drainage and clear obstacles. Base portion  102  may be formed from an extrusion and as shown, include a plurality of passages to mitigate excess weight. The specific passages shown in the figures are exemplary only. More, fewer or different passage may incorporated into base portion  102  in various embodiments of the invention. 
     Each rail  104  generally has channels  108  formed within an A-shaped cross-section to provide a generally male interlocking shape for spring clip unit  110 , which is shown in detail at  FIG. 1B . 
     Spring clip unit  110  includes foot  112 , which here is configured as an elongated body with a generally female cross-section that is complimentary with respect to rails  104  of base portion  102 , to enable the spring clip unit  110  to slide over rails  104 . Foot  112  supports a PV module coupling device  114  adapted to engage the frames of at least two PV modules while maintaining a space in between them. 
     Elongated beam  124  leads to PV module mounting platform  126  that supports PV module coupling device  128  configured to couple together the frames of at least two photovoltaic modules. PV module coupling device  128  in  FIGS. 1A and 1B  is a “rock-it” style connector manufactured by SolarCity Corp., which is arranged to connect to respective frames of two adjacent PV modules. Such a coupling device is described and illustrated, for example, in commonly assigned U.S. patent application Ser. No. 14/615,320, Publication No. 2015/0155823-A1, the disclosure of which is herein incorporated by reference in its entirety. However, system  100  is not limited to use of such a coupling device. A multitude of different styles of coupling devices are compatible with the system, for example, such as the coupling device  132  illustrated at  FIG. 4 , which depicts a clamping-style coupling device  132  with an upper and lower clamp arranged to clamp the top and bottom portions of a PV module. 
     Continuing with  FIGS. 1A and 1B , spring clip unit  110  includes first spring clip  116  having a wire-form structure forming lever portion  118  that extends laterally away from foot  112 . The wire-form structure also extends to first tab  120  and second tab  122  that extend through passages within the foot  112 . Spring clip unit  110  also includes second spring clip  124  having a pair of bodies extending in cantilever from foot  112  and having sets of teeth angled downwardly towards the top of rail  104 , however, only one body can be used. 
     The wire-form structure of first spring clip  116  also includes corner portions  126  that lay between lever portion  118  and first tab  120  and second tab  122 . The wire-form structure is formed such that corner portions  126  place compressive force against tapered sides  128  of foot  112 . Hence, travel along tapered sides  128  causes corner portions  126  to narrow and widen with respect to each other, which causes first tab  120  and second tab  122  to narrow and widen in the same manner. 
     In use, spring clip unit  110  is placed over rail  104  with lever portion  118  in a raised position, as shown at  FIGS. 2A and 2B . In this position, first tab  120  and second tab  122  are withdrawn within foot  112 , due to the corner portions  126  of the first spring clip  116  interacting with the tapered sides  128  of the foot  112 . The relative positioning of corner portions  126  with respect to the varying width of foot  112  causes first tab  120  and second tab  122  to spread relatively wide, and hence forcibly away from one another. 
     As seen in  FIGS. 2C and 2D , moving lever portion  118  downward causes first tab  120  and second tab  122  to move inward due to the relative thinning of the width of foot  112  with respect to the corner portions  126 , as corner portions  126  move upward along the tapered walls  128  of the foot  112 . This causes first tab  120  and second tab  122  to simultaneously narrow and rotate, and thereby frictionally interlock with channels  108  of rail  104 , and thus prevent relative movement between spring clip unit  110  and base portion  102 . Advantageously, locking spring clip unit  110  may be performed manually without the use of tools. In various embodiments, the ends of first tab  120  and second tab  122  may be shaped (e.g., tapered, cammed, and/or beveled) to assist in this motion. Here, first tab  120  and second tab  122  are tapered and beveled, although that is not required. 
     In addition, second spring clip  124  is preloaded against the rail  104  to help prevent relative vertical movement between spring clip unit  110  and base portion  102 , as well as to provide an electrical ground path between PV module coupling device  114  and base portion  102 . 
       FIG. 3  shows double spring clip unit  130 , which is structurally similar to spring clip unit  110  shown at  FIG. 1B . The difference between spring clip unit  130  of  FIG. 3  and spring clip unit  110  of  FIGS. 1A, 1B, and 2  is that the foot  112   b  is longer and provisioned for an additional levered first spring clip  116  to allow for spanning over the passage  105  in base portion  102 , and thus over a lag bolt penetrating through the base portion  102 . Also, because foot  112   b  is longer than foot  112  and has two clamps that engage channels  108 , foot  112   b  may provide a relatively stronger connection to base portion  102 . 
       FIG. 4  shows a plurality of systems  100  mounted to a roof and supporting a plurality of PV panels. As shown, base portion  102  may advantageously be utilized to support more than one spring clip unit, although supporting more than one is not necessary. While system  100  is shown mounted to a sloped composite shingle roof, system  100  may be used on a variety of other structures. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.