Abstract:
A mounting support for mounting photovoltaic modules constructed with at least one glass pane on a flat roof surface includes a flexible elongated strip having a bottom side with a substantially smooth surface for attachment to the roof surface and a top side with a substantially smooth surface for supporting the photovoltaic modules. The top side of the strip includes recesses oriented perpendicular to the longitudinal direction of the strip and separating strip segments which allows the mounting support or strip to be easily rolled up. The strip segments include integrally formed fastening members configured to engage with cooperating fasteners for securing the photovoltaic modules on top side of the strip. The top surface may also include longitudinal grooves or tubes holding the fastening members.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of German Patent Application, Serial No. 10 2007 056 619.2, filed Nov. 23, 2007, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a photovoltaic module, and more particularly to a support for installing a photovoltaic module on a roof. 
         [0003]    Nothing in the following discussion of the state of the art is to be construed as an admission of prior art. 
         [0004]    Solar energy collectors can be installed on a flat roof by arranging photovoltaic or solar modules constructed with glass panels in side-by-side relationship. These modules are planar panel-like assemblies in form of rectangular or square panels. The panels are typically supported on the roof surface (e.g., tarpaper, tiles, plastic foil) by concrete blocks placed on the flat roof, with a corresponding support structure connected to the concrete blocks. The modules are mounted on the support structure. As the support structure, which may further include concrete blocks, is very heavy, this weight must be taken account in static calculations for the roof and the building. In addition, the material costs are also very high. 
         [0005]    The German utility model DE 20 2006 016 382 U1 discloses a support structure which includes upper rooftop supports, support braces, transverse shelves and bottom supports and is placed on a water-tight roof surface by interposing construction mats and held only by gravity, i.e., without being anchored, because the weight anchors the structure. This structure, a concrete blocks/support structure as well as a support structure constructed from support braces, will be generally referred to as “mounting support”. A drawback of the support structure described in DE 20 2006 016 382 U1 is the use of modular photovoltaic foils which are connected with a mounting foil glued to the roof surface of the flat roof because of a low energy efficiency of the modular foil. 
         [0006]    It would therefore be desirable and advantageous to provide an improved support for mounting photovoltaic modules on a flat roof surface to obviate prior art shortcomings and to eliminate the heavy substructure typically associated with the installation of photovoltaic cells disposed on a glass pane. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one aspect of the invention, a mounting support for mounting photovoltaic modules constructed with at least one glass pane on a flat roof surface includes a flexible elongated strip configured to be wound and unwound in a longitudinal direction of the strip, wherein a bottom side of the strip has a substantially smooth surface for attachment to the roof surface and a top side of the strip has a substantially smooth surface for receiving the photovoltaic modules, and fastening members arranged in the top side of the strip with a predetermined spacing therebetween in the longitudinal direction and forming an integral component of the strip, wherein the fastening members are configured to engage with cooperating fasteners for securing the photovoltaic modules on top side of the strip. 
         [0008]    This type of support advantageously allows mounting of photovoltaic modules based on glass technology without a heavy substructure. The support according to the invention (here also referred to as flexible tape, mounting foil, web) can be readily transported when rolled up, and can be easily handled during installation. The mounting support is already well prepared for the installation because the fastening members are preinstalled. The proposed mounting device is not limited to flat roofs. 
         [0009]    By using supports with different heights, the angle of incidence of the radiation onto the photovoltaic modules can be adjusted. For example, the angle of incidence can be adapted to optimize the angle of incidence for roofs with a predetermined pitch. Advantageously, the bottom side of the strip may be attached to the roof surface with an adhesive, or longitudinal edges of the bottom side of the strip may be welded to the roof surface. 
         [0010]    According to another advantageous feature of the present invention, the top side of the strip may include recesses oriented perpendicular to the longitudinal direction of the strip, with the recesses separating corresponding strip segments, and the fastening members may be arranged in a part of the strip segments. With this approach, elongated mounting supports can be provided which may prevent the material from protruding over the edges of the rolled-up support. In addition, rainwater entering between the photovoltaic modules can be easily diverted to the sides. 
         [0011]    According to another advantageous feature of the present invention, the repeat pattern between two adjacent fastening members can correspond to, for example, four or five segments. However, other repeat patterns are feasible depending on the application. 
         [0012]    According to another advantageous feature of the present invention, the top side of the strip may include grooves oriented in the longitudinal direction of the strip and forming ribs therebetween, wherein the fastening members are arranged in at least part of the ribs. In this way, the repeat pattern can advantageously be freely selected, because there a no longer defined transverse grooves in form of recesses. 
         [0013]    According to another advantageous feature of the present invention, the top side of the strip may include a plurality of small tubes, with the fastening members, e.g., a threaded element, being arranged in at least one of the tubes. Such tube system, which preferably has a honeycomb structure, allows the mounting support to be easily rolled up, while still allowing a flexible installation. 
         [0014]    It should be mentioned that the fastening members should protrude only slightly over the top side of the mounting support, so that the mounting support can be uniformly rolled up into a roll. A maximum overhang of half the thickness of the support can already be considered as a limit. Advantageously, the overhang does not to exceed 30%, preferably 15%, of the thickness of the support. Most preferably, the fastening members is completely integrated in the support so as not to hinder the support from being rolled up or unrolled. 
         [0015]    The fastening members in the segments, webs or tubes may advantageously include threaded sleeves integrated in the mounting support which are adapted to receive clamps. This allows the use of frameless photovoltaic modules. For example, a photovoltaic foil is placed between two glass panes in form of a sandwich structure. The fastening members are designed so as to readily withstand a suction force of about 15 kg/m 2 . This can be accomplished, for example, by attaching anchors to the threaded sleeves or by selecting other types of fastening members. 
         [0016]    The mounting support (mounting foil, web, tape) can be constructed in a single piece, wherein the recesses may be cut or milled from a plastic foil having a thickness of between 1 cm to 3 cm (single-layer construction) for forming the intermediate segments. However, a mounting foil consisting of two layers in form of a sandwich construction (two-layer construction) may also be employed. The bottom side is configured for attachment to the roof surface and the top side is adapted to secure the photovoltaic modules and may have transverse recesses, longitudinal grooves or tubes. In both embodiments, the mounting foils are flexible, i.e., bendable. 
         [0017]    The shape of the recesses, grooves or tubes is not critical, provided they allow the support to be wound onto a winding spindle without squeezing the material. 
         [0018]    Depending on the mounting method on the roof layer and the fastening members, the lateral edges of the mounting support may advantageously also include a recess, which could be used, for example, to precisely guide a welding apparatus. In a two-layer structure, the bottom layer would then be continuous without recesses, whereas the top layer would have island-shaped raised portions representing the segments. Such embodiment would be of interest because of low material consumption and a small weight. 
         [0019]    In general, the modules described above are placed essentially parallel to the roof surface. In the finished structure, the unrolled mounting support would be attached to the roof layer, while another similar mounting support may be secured in parallel alignment thereto on the roof layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0020]    Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which: 
           [0021]      FIG. 1  shows a conventional structure with photovoltaic modules on a flat roof; 
           [0022]      FIG. 2  shows a conventional structure with a photovoltaic foil on a flat roof; 
           [0023]      FIG. 3  shows a top view of a mounting support according to the invention; 
           [0024]      FIG. 4  shows a cross-sectional view of the mounting support of  FIG. 3 ; 
           [0025]      FIG. 5  shows a cross-sectional view of a single segment of  FIG. 4 ; 
           [0026]      FIG. 6  shows the rolled-up mounting support or mounting foil; 
           [0027]      FIG. 7   a  shows a top view of a mounting support with a grooved structure; 
           [0028]      FIG. 7   b  shows a cross-sectional view of the mounting support taken along the line X-X in  FIG. 7   a;    
           [0029]      FIG. 7   c  shows a side view with a grooved structure of another embodiment of the mounting support taken along the line Y-Y in  FIG. 7   a;    
           [0030]      FIG. 8   a  shows a top view of another embodiment of a mounting support with a honeycomb structure; 
           [0031]      FIG. 8   b  shows a cross-sectional view of the mounting support taken along the line Z-Z of  FIG. 8   a;  and 
           [0032]      FIG. 9  shows a structure with two differently attached mounting supports. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0033]    Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. 
         [0034]    Turning now to the drawing, and in particular to  FIGS. 1 and 2 , there are shown two conventional methods for securing a solar collector facility to a flat roof.  FIG. 1  shows a conventional installation of photovoltaic modules, wherein concrete blocks  1  placed on a water-tight and air-tight roof surface  15  of a roof. Connected thereto is a support structure  3 , on which conventional photovoltaic modules  5  constructed with glass panes are mounted. Disadvantageously, this overall structure is heavy, so that its weight and structural arrangement must be taken into consideration when performing static calculations. Moreover, large quantities of materials are required. However, the photovoltaic assembly has a high efficiency, because the photovoltaic modules  5  with one or two glass panes can be mounted at a favorable angle with respect to the horizontal orientation of the roof. 
         [0035]      FIG. 2  depicts a second conventional installation, wherein a mounting foil  7  is glued on the roof surface  15  of a flat roof, and a photovoltaic module foil  9  is connected to the foil  7 . This embodiment generates only a small roof load and has low material costs. However, the efficiency of module foils is also low. Installation is simple and advantageous, because the foils  7 ,  9  only need to be rolled out in a winding/unwinding direction  11  and connected to the roof surface with an adhesive or by welding. 
         [0036]    Referring now to  FIG. 3 , there is shown a schematic illustration of an embodiment according to the invention with two elongated mounting supports  13  arranged in parallel, which may also be referred to as mounting foil. These may be constructed of a relatively thin plastic foil and are flexible. On the left side of  FIG. 3 , three photovoltaic modules  5  having a top side with glass pane  6  are mounted adjacent to each other on the supports  13 , whereas the right side of  FIG. 3  shows a region of a roof surface  15  where modules  5  have not yet been placed. The modules  5  are here configured as frameless modules. A second glass pane may be disposed on the backside. 
         [0037]    The mounting supports  13  may be constructed in form of elongated strips, tapes or webs having a width in a range between 10 cm and 20 cm and a length of, for example, between 5 m and 12 m. They may be rolled up before installation to save space (see  FIG. 6 ). Recesses  17  are cut or milled into the surface of each support  13  which extend from edge to edge of the strip, defining segments  19  therebetween. This shape of recesses  17  is advantageous for single-layer and two-layer foils. The segments  19  formed in this way extend transversely to the winding/unwinding direction  11  and have a length corresponding to the width of the mounting support  13 . In particular, the cross-section of the recesses  17  can be wedge-shaped or triangular. 
         [0038]      FIGS. 4 and 5  show two-layer mounting supports  13  formed of two layers  13 A,  13 B (sandwich construction), wherein the bottom layer  13 A represents the actual mounting foil for attachment to the roof surface  15 . The layer  13 A is configured to connect to the actual roof surface  15  (roofing paper, copper roof, plastic roof, layer of smooth tiles, etc.). The top layer  13 B forming the segments  19  is adapted to securely attach the photovoltaic modules  5 . In the embodiment with a single-layer as well as with a two-layer support  13 , the bottom side of the mounting support  13  has a substantially planar structure, so that it can be fixedly attached to the roof surface  15 , in particular glued by using an adhesive or welded at its edges. The top side has a substantially planar structure adapted to support and securely hold the photovoltaic elements  5 . 
         [0039]    In the exemplary embodiment depicted in  FIGS. 3-5 , the thickness T of the composite support  13 A,  13 B may be between 50 mm and 30 mm. The two layers  13 A,  13 B may in principle be constructed of different materials. For example, the top layer  13 B may be made of a glass fiber reinforced material. 
         [0040]      FIG. 4  shows a complete centrally located rectangular module  5  and a partial view of two adjacent identical modules  5  disposed on either side, wherein the glass pane  6  has been omitted.  FIG. 5  shows in part two adjacent modules  5 . 
         [0041]    As seen from the exemplary embodiment depicted in  FIGS. 3 and 4 , each fourth segment  19  has a fastening member  23 , wherein the fastening members  23  have a spacing R which corresponds to the width M of a module  5 . In this way, at least one photovoltaic module  5  can be connected at its edges directly or indirectly with the support  13 . However, it will be understood that instead of each fourth segment  13  any other suitable pattern can be selected for the spacing between the fastening members, for example six segments  19 . 
         [0042]    Is the exemplary embodiment depicted in  FIGS. 4 and 5 , the fastening member  23  is implemented as a threaded sleeve or bushing  25  inserted in the top layer  13 B. The sleeve or bushing  25  is connected with one or more anchoring wings  27  (see  FIG. 5 ) to prevent it from being pulled out of the support. As illustrated in the left part of  FIG. 3  and in  FIGS. 4 and 5 , a corresponding screw  30  is screwed into the thread of the sleeves or bushings  25 . The screw  30  holds a clamp  29 , for example a metal clamp, which is supported on the surface of adjacent modules near their respective edges, thereby affixing the corresponding module  5  on the mounting support  13 . As shown in  FIGS. 4 and 5 , the clamp  29  is here particularly formed as a two-sided clamp. The clamp  29  shown in  FIG. 5  therefore secures both the right edge of the left module  5  and the left edge of the right module  5  to the top surface of the support  13  (shown here with a spacing). In other words: adjacent modules  5  on each fastening member share a clamp  29  after completion of the connection. 
         [0043]    Preferably, a spacer made of a soft material, for example rubber, is placed between the bottom side of the clam  29  and the top surface of the respective module  5 . 
         [0044]    It is important for ease of handling that the fastening members  23  form an integral component of the tape  13 . 
         [0045]      FIG. 6  shows a rolled-up mounting or attachment support  13 . For clarity, the individual layers on the drum are here shown as being spaced apart. The recesses  17  and the segments  19  facilitate winding of the mounting support  13 . It is evident from  FIG. 6  that the diameter D of a winding spindle  26  needs to be taken into account in the design of the mounting support if the mounting support  13  is to be wound on a winding spindle  26 . As also clearly shown in  FIG. 6 , the fastening members  23  arranged along the strip form an integral component of the mounting support  13 . 
         [0046]      FIGS. 7   a,    7   b,    7   c  illustrate an alternative embodiment of the invention, wherein instead of the transverse recesses  17 , longitudinal grooves  31 , which define the ribs  33 , are provided in the mounting support  13 . The grooves  31  can be U-shaped (see  FIG. 7   b ). Fastening members  23  are inserted in the ribs  33  with a predetermined spacing R therebetween. The surface of the ribs  33  forms a plateau  35  representing a flat support surface or structure configured to receive the photovoltaic modules  5 . 
         [0047]    As shown on the outermost right rib  33  in  FIG. 7   c  (side view Y-Y), the ribs  33  may in addition include transverse recesses  37  which make it easier to roll up the mounting support  13 . This produces cross-ribs with trapezoidal cross-section in the side view Y-Y. 
         [0048]      FIGS. 8   a,    8   b  show a mounting support  13  which, instead of the recesses  17  or grooves  31 , has a plurality of closely spaced small tubes  39  which are closed off at the bottom. The tubes  39  may preferably have the illustrated honeycomb structure, but may also have in cross-section the shape of a circle, rectangle or a truncated cone. In the depicted exemplary embodiment, the upper free ends of the tubes form the flat support surface or structure for receiving the photovoltaic modules  5 . In the depicted exemplary embodiment, the fastening member is disposed in one of the centrally located tubes  39   a.  The fastening member can also be implemented as a thread or a threaded sleeve. Similar to the embodiment described above with reference to  FIGS. 4 and 5 , a screw  30  for a clamp  29  can be screwed into the corresponding thread for securing the (unillustrated) module  5 . The tubes  39   b  adjoining the central tube  39   a  can be reinforced with a filler  41  so as to create a mechanically stable mounting support (formed by the top layer  13 B). The remaining tubes  39   c  may then be hollow, enhancing the flexibility and contributing to material savings and weight reduction. 
         [0049]      FIG. 9  corresponds to a cross-section similar to that of  FIG. 1 . In general, a first mounting support  13  is attached to the roof surface  15  in an unrolled configuration, with a second unrolled mounting support  13 ′ being attached on the roof surface  15  parallel to the first mounting support. In the exemplary embodiment depicted in  FIG. 9 , the first support  13  is attached to the roof surface  15  with an adhesive  45  in form of an adhesive layer, while the second (identical) support  13 ′ is attached to the roof surface  15  by two longitudinal weld seams  47 . it will be assumed that each clamp  29  (having a U-shaped cross-section) secures two modules  5  extending perpendicular to the drawing plane. 
         [0050]    While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. For example, the modules and the mounting support may be connected with a snap connection instead of threaded sleeve, wherein the eyelet is incorporated in the mounting support and the ball-shaped part is fixedly installed in the module. It is only necessary that the fastening members are able to withstand the applied forces, i.e., being fixedly anchored in the mounting support, and that they are flush with or recessed in the top side of the mounting support, forming an integral component of the mounting support, meaning that they cannot be detached from the mounting support without damaging or destroying the mounting support. 
         [0051]    The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. 
         [0052]    What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: