Patent Publication Number: US-2013240008-A1

Title: System and method for mounting photovoltaic modules

Description:
FIELD OF THE INVENTION 
     Embodiments of the invention relate to a photovoltaic module mounting system, and more particularly to systems and methods for mounting photovoltaic modules to a support structure using adhesive mounting pads attachable to the modules and having first engaging elements. 
     A photovoltaic module is a device that converts sunlight energy into electricity. Photovoltaic modules include a plurality of photovoltaic cells, also known as solar cells, for example, crystalline silicon cells or thin-film cells. The photovoltaic cells are typically formed between front and back support panels of the photovoltaic module. In thin-film photovoltaic modules, the photovoltaic cell can include sequential layers of various materials formed between the front panel and the back panel. The material layers can include, for example, a transparent conducting oxide (TCO) layer, an active material layer, and a back contact layer. The active material layer may include at least a semiconductor window layer and a semiconductor absorber layer, each formed of one or more layers of semiconductor material. As one example, a window layer can be formed of cadmium sulfide (CdS), and an absorber layer can be formed of cadmium telluride (CdTe) or copper indium gallium diselenide (CIGS), or other suitable semiconductor light absorbing material. 
     The front and back panels provide structural integrity and protect the solar cells from environmental hazards. The front and back panels are made of a transparent material, for example, glass. The transparent front panel allows light to pass through to the active material layer. As light strikes the active material, the active material generates electricity. 
     The installation of photovoltaic modules can be a cumbersome process. In conventional installation systems, brackets are often used to fasten peripheral edges of the photovoltaic modules onto support structures. Since photovoltaic modules are held at their edges, they must include robust front and back panels to support the weight of the photovoltaic modules and to endure any environmental stresses, such as wind, to which they may be subjected. Accordingly, tempered glass is often used as front and back panels. In some systems, frames are formed around each photovoltaic module to provide additional support and to aid in installation. Framed photovoltaic modules are also connected to a support structure by brackets at their edges. 
     The strong front and back panels and/or frames required for conventional installation systems increase costs of the photovoltaic modules. Further, the added weight makes shipment and installation more difficult and time consuming. Accordingly, there is a need for a photovoltaic module mounting system that provides improved support for photovoltaic modules, enables the use of less robust front and back panels, which can be lighter and/or less rigid, and increases the speed of installation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a top view of an adhesive mounting pad with a male engaging element; 
         FIG. 2  illustrates a side view of an adhesive mounting pad with a male engaging element; 
         FIG. 3  illustrates a side view of a photovoltaic module with an adhesive mounting pad adhered thereto, and a support rail with a female engaging element that is flush with a surface of the rail; 
         FIG. 4  illustrates a side view of a photovoltaic module with an adhesive mounting pad having a male engaging element that is connected to a female engaging element of a support rail; 
         FIG. 5  illustrates a side view of a photovoltaic module with an adhesive mounting pad adhered thereto, and a support rail with a female engaging element that protrudes from a surface of the rail; 
         FIG. 6  illustrates a side view of a photovoltaic module with an adhesive mounting pad that has a female engaging element, and a support rail with a male engaging element recessed into a surface of the support rail; 
         FIG. 7  illustrates a side view of a photovoltaic module with an adhesive mounting pad that has a female engaging element, and a support rail with a male engaging element protruding from a surface of the support rail; 
         FIG. 8  illustrates a side view of a photovoltaic module with an adhesive mounting pad with an alternative male engaging element adhered thereto and a support rail; 
         FIGS. 9-10  illustrate a side view of a method of connecting a photovoltaic module with an adhesive mounting pad to a support rail; 
         FIG. 11  illustrates a side view of a photovoltaic module with an adhesive mounting pad having a female engaging element adhered thereto and a support rail with an modified male engaging element; 
         FIG. 12  illustrates a top down view of a photovoltaic modules with adhesive mounting pads having first engaging elements; 
         FIG. 13  illustrates a top down view of a support structure with second engaging elements; 
         FIG. 14  illustrates a top down view of photovoltaic modules connected to a support structure using adhesive mounting pads having first engaging elements; 
         FIG. 15  illustrates a top down view of photovoltaic modules connected to a support structure using adhesive mounting pads having first engaging elements in accordance with an embodiment described herein; 
         FIG. 16  illustrates a perspective view of a support rail with an installation channel; 
         FIGS. 17A-17B  illustrate an installation of a photovoltaic module with male engaging elements on a support rail with an installation channel; 
         FIGS. 18A-18B  illustrate an installation of a photovoltaic module with male engaging elements on a support rail with an installation channel and a graduated indentation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and which illustrate specific embodiments of the invention. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to make and use them. It is also understood that structural, logical, or procedural changes can be made to the specific embodiments discussed herein, without departing from the spirit or scope of the invention. 
     Described herein is a system and method for mounting photovoltaic modules to support structures using a plurality of spaced adhesive mounting pads that adhesively mount to the back panel of a module with each having a first engaging element for engaging with a respective second engaging element provided on a support structure. The adhesive mounting pads support the photovoltaic modules at a plurality of points on the back panel, and also provide a quick installation method. Since the modules are supported at a plurality of points across the back panel, this system enables the use of less robust, e.g., thinner, front and back panels. The system also obviates the need for stronger supports or frames typically required to support photovoltaic modules. The system of the present application may be used with photovoltaic modules having non-tempered cover glass and thin substrate glass panels, and is applicable to any application requiring the mounting of framed or unframed modules to a support structure. 
       FIGS. 1 and 2  respectively illustrate a top view and a side view of an adhesive mounting pad  10  having a first engaging element  40  in accordance with an embodiment described herein. The adhesive mounting pad  10  includes an adhesive  20 , which may be formed as a layer, for adhering the mounting pad  10  to a back panel of a photovoltaic module, a spacer pad  30 , and a first engaging element  40  formed as a male engaging element. 
     The adhesive  20  can be any adhesive material suitable for adhering the adhesive mounting pad  10  to a photovoltaic module, for example, a silicone adhesive or a foam double sided adhesive. The adhesive  20  may be formed as a layer on spacer pad  30 . 
     The spacer pad  30  is shown in  FIGS. 1 and 2  as a circular pad, but can be of any other shape. For example, the spacer pad  30  can be square, rectangular, or any other polygonal shape. Likewise, adhesive  20 , shown in the figures as being circular, can be of any shape. Further, the spacer pad  30  and adhesive  20  can be of different sizes, with larger diameter spacer pads  30  and adhesives  20  supporting larger surfaces of the photovoltaic module, as desired. As an example, the spacer pad  30  and adhesive  20  can be round and between two and eight inches in diameter. Different thicknesses of the spacer pad  30  can also be used to provide a larger or smaller gap between the photovoltaic module and the supporting structure, as described below. As an example, the spacer pad  30  can be between one quarter inch and two inches thick. In one embodiment, the spacer pad is round and has a diameter of about four inches and a thickness of about one inch. The spacer pad  30  can be constructed of a material that is not electrically conductive, such as a plastic or rubber material, to provide electrical isolation between the photovoltaic module and the support structure. 
     As shown in  FIG. 3 , the first engaging element  40 , shown as a male engaging element, connects with a complementary second engaging element  50 , shown as a complementary female engaging element provided at a support structure, such as a plurality of support rails  200 . Any suitable connection mechanism providing first and second engaging elements which provide a secure connection between two elements can be utilized, including quick connect mechanisms such as snap connectors, and releasable quick connect mechanisms. 
     A plurality of adhesive mounting pads  10  can be mounted to a back panel of a plurality of photovoltaic modules  100  either during manufacture of the photovoltaic module, or after manufacture, but prior to module installation in the field. Once the mounting pads  10  are mounted on the back side of a module  100 , the photovoltaic module is then connected to a support structure, such as rail  200 , by engaging each first engaging element  40  with a complementary engaging element  50  provided at the support structure. 
     The support rails  200  can be part of a support structure that supports a photovoltaic array above a surface, for example, above ground or above a structure such as a roof of a building. The support rails  200  have the complementary second engaging elements  50  formed as a female engaging element having retractable spring loaded retainers  24 . The second engaging elements  50  can be attached to the support rails, for example, by welding, by an adhesive or by using fasteners such as screws or bolts, or can be constructed as an integral part of the support rail  200 , for example, as a recess formed in the rail structure. The second engaging element  50  can be flush with a surface of the support rails  200  as illustrated in  FIGS. 3-4 , can be configured to protrude from a surface of the support rails  200  as illustrated in  FIG. 5 , or can be below an upper surface of the support rails  200  as illustrated in  FIGS. 17A and 17B . 
     Each first engaging element  40  on a module  100  connects with a respective second engaging element  50  on a support rail  200  and, when the two engaging elements are connected, the module  100  is secured to the support structure, e.g., support rail  200 . On the second engaging element  50  shown in  FIG. 3 , retractable spring-loaded retainers  24  line up with indentations  26  in the sides of the first engaging element  40  and hold the first engaging element  40  in place when the first engaging element  40  is pressed into and connected with the second engaging element  50 . While shown in  FIG. 3  with two retainers  24 , any number of retainers  24  can be used, including one retainer  24 . The first engaging element  40  and second engaging element  50  can each be tubular in shape, with one or more retainers  24  arranged in a circle around an inside circumference of the second engaging element  50 , and the indentations  26  arranged continuously around a circumference of the first engaging element  40  as a groove. The second engaging element  50  shown in  FIG. 3  also includes a quick release mechanism  25  that, when pressed, causes the first engaging element  40  to be released by retracting the spring loaded retainers  24  into the body of the second engaging element  50 . 
       FIG. 4  illustrates the photovoltaic module  100  connected to the support rail  200 . When the first engaging element  40  and the second engaging element  50  are connected, the spacer pad  30  creates a space  600  between the underside of photovoltaic module  100  and the support rail  200 . The spacer pad  30  supports the weight of the photovoltaic module  100 . As noted earlier, the spacer pad  30  can have different thicknesses to provide a different space  600  between the modules  100  and the rail  200 . When connected, as in  FIG. 4 , the first engaging element  40  is securely held in place by the retainers  24  of the second engaging element  50 . The photovoltaic module  100  can be disconnected from the support rail  200  by pressing the quick release button  25 . 
     The configuration of the first engaging element  40  as a male engaging element, and the complementary second engaging element  50  as a female engaging element provided flush with a rail  200  in  FIGS. 2-4  is merely one example configuration of a connection mechanism, and it should be understood that other configurations can be used. For example,  FIG. 5  illustrates an embodiment with a second engaging element  51  that is a female engaging element protruding from a surface of the support rail  200 . In this embodiment, a quick release button  29  is located on the side of the second engaging element  51 . The second engaging element  51  can be pressed into the first engaging element  40  so that they are connected to one another in the same manner as described above with reference to  FIGS. 3 and 4 . 
     In another embodiment, illustrated in  FIG. 6 , a first engaging element  53  with static retainers  72  is located on the adhesive mounting pad  10 . A second engaging element  48  is a male engaging element that is located in a recess  210  of the support rail  200 . The first engaging element  53  is connected to the second engaging element  48  by pressing it into the second engaging element  48  in the direction indicated by arrow A. In the  FIG. 6  embodiment, a quick release button  27  is located on a back side of the support rail  200 , and causes spring loaded retainer tabs  66  of the second engaging element  48  to compress to the width shown by lines  65  so that it can disengage from the static retainers  72 . A plurality of spring loaded retainer tabs  66  can be formed around the circumference of the second engaging element  48 . 
     In yet another embodiment, illustrated in  FIG. 7 , a first engaging element  54  is a female engaging element located on adhesive mounting pad  10 , and a second engaging element  49  is a male engaging element that protrudes from a support rail  200 . In this embodiment, material of the spacer pad  32  is formed around the first engaging element  54 , so that portions of the material will sit flush with the support rail  200  when the first engaging element  54  is pressed into and connected with the second engaging element  49 . When connected, the height of the spacer pad  32  defines a space between the support rail  200  and the photovoltaic module  100 . As in  FIG. 6 , a quick release button  28  is located on a back side of the support rail  200 . In this embodiment, the space between the back side of module  100  and rail  200  is determined by the thickness of spacer pad  32 . 
       FIG. 8  illustrates a side view of a photovoltaic module with an adhesive mounting pad that has a modified first engaging element  41  that connects to a female engaging element formed as a hole  900  and surrounding structure of a rail  200 . The modified first engaging element  41  includes a center shaft  42  and two wings  43 , which are made out of a flexible material, such as plastic or a metal. The modified first engaging element  41  is connected by moving the photovoltaic module  100  in the direction indicated by arrow A so that the modified first engaging element  41  passes through the hole  900  in the support rail. In this embodiment, the second engaging element is the hole  900  and surrounding lower surface of rail  200 . 
       FIG. 9  shows an adhered mounting pad  10  with a modified first engaging element  41  in the process of being pressed into and connected to support rail  200 . The flexible wings  43  bend inwards as they pass through the hole  900  with the application of sufficient pressure.  FIG. 10  shows connection of module  100  to rail  200  after the modified first engaging element  41  has passed through the hole  900 . As illustrated, the flexible wings  43  are returned to their original position and grip the back surface of rail  200  surrounding hole  900 . Since the flexible wings  43  have now expanded outwards, they prevent the movement of the modified first engaging element  41  back out of the hole  900 , and thus the photovoltaic module  100  is securely connected to the support rail  200 . To release the photovoltaic module  100 , the tops of the flexible wings  43  can be pushed inward, in the direction shown by arrows F and G in  FIG. 10 , so that the modified first engaging element  41  can pass back through the hole  900 , releasing the connection of module  100  to rail  200 . 
     In another embodiment shown in  FIG. 11 , the second engaging element  44  is formed as a center shaft  42  with flexible wings  43  located on the support rails  200  while the first engaging element  57  is formed as a hole  901  provided in a spacer pad  34 . A connection is made by pressing the first engaging element  57  into the second engaging element  44  and thus inserting the center shaft  42  and flexible wings  43  into the hole  901 , which includes a tunnel portion  902  and an opening  903  having a wider diameter than tunnel portion  902 . The connection is held by the flexible wings  43 , which expand once they have been inserted past the tunnel portion  902  and into the opening  903 . In the  FIG. 11  embodiment, the quick release mechanism is formed as a tab  53  which is connected by connector  54 , which may be a string or wire material. When the tab  53  is pulled, the flexible wings  43  are pulled and flex inward toward the center shaft  42 . Once the flexible wings  43  have been flexed inward toward the center shaft  42 , the second engaging element  44  can be pulled out through the tunnel portion  902 , releasing the connection. 
     The embodiments of the first engaging element and second engaging element illustrated in  FIGS. 1-11  provide specific examples of connection mechanisms for connecting a module  100  to support structures such as support rails  200 , but it should be understood that variations of these connection mechanisms, and other connection mechanisms, are within the spirit and scope of the invention. Any connection mechanism can be used whereby a first engaging element of the adhesive mounting pad  10  is connected to a second engaging element associated with rail  200 . This includes quick connect mechanisms, mechanisms with a quick release property, or any other secure semi-permanent or permanent connection mechanism. 
       FIG. 12  illustrates a top down view of a photovoltaic module  100  with attached adhesive mounting pads  10 . Multiple adhesive mounting pads  10  are adhered to the back side module  100 , so as to provide multiple points of support.  FIG. 12  shows four adhesive mounting pads  10  on a photovoltaic module  100 , but more or less can be used, providing more or less structural support for the photovoltaic module  100 . 
       FIG. 13  illustrates a top down view of a support structure  300 . The support structure  300  includes a plurality of cross support rails  200  onto which photovoltaic modules  100  can be mounted. The support structure  300  can include parallel support beams  400  that are connected by the cross support rails  200 . In the  FIG. 13  embodiment, each cross support rail  200  includes two second engaging elements  51 . Alternatively, the second engaging elements  51  could be located on the parallel beams  400  as shown in  FIG. 15 . 
       FIG. 14  illustrates a top down view of three photovoltaic modules  100  connected to support structure  300 . Any number of photovoltaic modules  100  can be aligned in a row, and a plurality of adjacent rows of mounted photovoltaic modules  100  can form a photovoltaic array. First engaging elements of the adhered mounting pads  10  are connected to the second engaging elements of the support structure  300  to form connected elements  55 . In the  FIG. 14  embodiment, each photovoltaic module  100  is connected to cross support rails  200  at four points by connected elements  55 . Additional connected elements  55  can be used to provide additional support for the photovoltaic modules  100 . While shown here with a space  800  between the photovoltaic modules  100 , the modules could also be arranged directly adjacent one another, without a space  800  between them. 
     The photovoltaic modules  100  can be connected to the support structure  300  in any orientation. For example,  FIG. 15  illustrates an embodiment with photovoltaic modules  100  connected lengthwise (with the shorter ends of the photovoltaic modules  100  adjacent one another). In  FIG. 15 , the connected elements  55 , which include the second engaging element, are attached to the parallel support beams  400 , instead of the cross support rails  200 , as shown in  FIG. 14 .  FIG. 15  shows two parallel rows B and C of photovoltaic modules  100 . 
     The rails  200  or beams  400  of the support structure  300  can include installation channels, or grooves, which assist in installation by guiding first engaging elements provided on a photovoltaic module into engagement with respective second engaging elements provided at the rails  200  or beams  400 .  FIG. 16  illustrates a perspective view of a support rail  200  with an installation channel  60  that runs the length of the support rail  200 . Installation channel  60  can run the full length of the support rail  200 , as shown in  FIG. 16 , or can be included only close to and at location  70  of the second engaging elements. The second engaging elements at location  70  are shown in  FIG. 16  as holes, but could also be male or female engaging elements as shown in  FIGS. 1-11 . The installation channel  60  allows the first engaging elements located on the back side of a photovoltaic module to be placed into the channel  60  on a nearby point on a rail, and to slide along the length of a rail until they reach the location  70  where a connection can be made between the first and second engaging elements. The installation channels  60  make it easier to align the module  100  with the connection locations on rail  200 . 
       FIGS. 17A-17B  illustrate a side view of a photovoltaic module  100  with the quick connect structure shown in  FIG. 3  being connected to a support rail  200  having an installation channel  60 . In  FIG. 17A , the first engaging element  40  is positioned at point P 1 , which is near the second engaging element  50 . The walls of the installation channel  60  restrict movement in the lateral direction, and hold the first engaging element  40  on the support rail  200  as it moves in direction H. To connect the photovoltaic module  100  with the support rail  200 , the photovoltaic module  100 , including the first engaging element  40 , is slid across the support rail  200  in direction H, until the first engaging element  40  drops into, and can be pressed into and connected with, the second engaging element  50  (shown in  FIG. 17B ). This installation method may be utilized with any of the embodiments described above. 
     Additional guides can be used, as well. For example, a graduated indentation  910 , or valley, may be formed in the rails  200  or beams  400  in areas that are near a connection point location  70 . The graduated indentation  910  may be graduated in either a longitudinal or lateral direction of the rail, or both, and can be used to guide the first connection elements on the module to the second connection elements at rails  200  or beams  400 . An exemplary graduated indentation  910  is illustrated in  FIGS. 18A-18B . In  FIGS. 18A-18B , the graduated indentation  910  is formed at locations near hole  900 , which is the second engaging element. The graduated indentation  910  may be formed at multiple respective points near holes  900  along the support rail  200 , and may be utilized in conjunction with an installation channel  60  formed between respective graduated indentations  910 , as shown in  FIGS. 18A-18B . When a first engaging element  41  is placed in the graduated indentation  910 , it moves in direction J by sliding, and assisted by gravity, toward the hole  900 . When it reaches the hole  900 , as in  FIG. 18B , it can be pressed in direction K to form a secure connection of module  100  and rail  200 . While shown here in a connection embodiment using the embodiment shown in  FIG. 8 , the graduated indentation  910  may be utilized with any first engaging element of the embodiments described herein. 
     While various embodiments have been described in detail, it should be readily understood that the invention is not limited to the disclosed embodiments. Rather the embodiments can be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not heretofore described without departing from the spirit and scope of the invention.