Abstract:
A protective cover for a solar panel is disclosed. The cover provides protection for the solar panel from the elements of the weather such as snow, hail, sleet, and windblown debris, and also against overheating of the solar panel during periods of long and intense solar radiation, when the demand for hot water is insufficient to dissipate heat build-up. The cover is constructed of material having heat-insulative properties and provides a barrier layer over the top of the solar panel to reduce the amount of heat transferred to the water tubes.

Description:
[0001]    This application claims priority from provisional application 61/052,367, filed on May 12, 2008, and from PCT application PCT/US2009/043543, filed on May 12, 2009 
     
    
     BACKGROUND INFORMATION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to covers for solar panels. More particularly, the invention relates to covers for solar panels that are exposed to intense solar radiation. 
         [0004]    2. Description of the Prior Art 
         [0005]    Solar panels that absorb solar energy for the purpose of heating, be it water or space, are sometimes at risk of overheating. An example of such a case is that of a solar system for heating water in a facility that is open only seasonally, such as a camp or ski lodge. In the case of a structure that is only seasonally occupied, the water in the heater tubes remains stagnant during the periods of non-use. Heat builds up and is only poorly dissipated if the water is not being circulated through the system. Such solar panels are also at risk of overheating even during times of usage, if, for example, the panels are exposed to long and intense periods of solar radiation, such as in the summer. Thus, in a residential structure that is occupied year-round in many parts of the US and that uses solar panels to obtain hot water, solar radiation in the summer may be very intense. The demand for hot water may not be sufficient to dissipate the heat quickly enough, particularly if the house is unoccupied because the residents are away on vacation. Solar energy panels that are used to provide heated water for radiant space heating of a structure, as well as hot water, are particularly at risk of overheating. These solar panels contain sufficient heat panels to satisfy the heat load in winter months. Once the cold weather is over, the solar panels are subject to risk of overheating, because the demand is so much reduced. 
         [0006]    What is needed, therefore, is a protective cover for solar panels, whether the solar panels are so-called flat panels or panels comprising an array of evacuated tubes. What is further needed is such a cover that is easily and quickly moved between an open position and a closed position. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The invention is a cover for use with solar panels. The cover provides protection from the elements of the weather, such as snow, hail, sleet, debris, and rain. The cover is also a solar radiation blacker and provides protection against overheating of the solar panel when it is subjected to intense solar radiation. 
         [0008]    The cover according to the invention must be removable or positionable, so as to allow the solar rays to impinge upon the solar panel when desired. The cover has an outer surface or outer protective shell that is weather-resistant and an inner shell or inner portion that has heat-insulative properties, to protect the solar panel from overheating. Various embodiments of the cover are provided herein according to the invention; some embodiments are manually fitted over and then removed from the solar panel, others are mechanically operated to cover and uncover the solar panel. Mechanically operated covers may have a wind-up mechanism that is manually operated, such as a crank that winds the cover around a shaft, have an electrically driven mechanism, such as a motor and linkages to wind the cover around a shaft or draw the cover up into a compact pleated or bunched configuration, or have segmented portions that are moved to an open or closed position in order to cover or uncover the solar panel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of the top of a rigid, removable protective cover according to the invention. 
           [0010]      FIG. 2  is a perspective view of the bottom of the cover of  FIG. 1 . 
           [0011]      FIG. 3  is an cross-sectional view of the cover of  FIG. 1 . 
           [0012]      FIG. 4  is a perspective view of the top of a soft, removable protective cover according to the invention. 
           [0013]      FIG. 5  is a perspective view of the bottom of the cover of  FIG. 4 . 
           [0014]      FIG. 6  is a cross-sectional view of the soft cover of  FIG. 4 . 
           [0015]      FIG. 7  is a perspective view of a third embodiment of the cover. 
           [0016]      FIG. 8  is a perspective view of a fourth embodiment of the cover. 
           [0017]      FIG. 9  is a side view of the cover shown in  FIG. 8 , illustrating linkages and connecting rods that are actuated move the protective panel sections to open and closed positions. 
           [0018]      FIG. 10  is a side view of the cover of  FIG. 8 , showing the cover closed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, the embodiments shown are provided so that this application will be thorough and complete, and will fully convey the true scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the figures. 
         [0020]    A conventional solar panel  4  is shown in several of the following drawings mounted on a conventional frame F. The frame F may be constructed so as to mount the solar panel  4  in an orientation that is parallel to an underlying surface, or be constructed to provide an incline that increases the direct impingement of the rays from the sun. The frame F is not included within the scope of the invention and is shown here only insofar as necessary to illustrate the inventive covers. 
         [0021]      FIGS. 1-3  illustrate a first embodiment of a solar panel cover  10  that is a rigid cover and  FIG. 4-6  illustrate a second embodiment of a cover  20  that is a soft cover. These two covers  10  and  20  are manually removable covers.  FIG. 1  is a perspective view of the top,  FIG. 2  a view of the bottom, and  FIG. 3  a cross-sectional view of the rigid cover  10 . The cover  10  comprises an outer shell or layer  1  constructed of a form-rigid material, a shock-absorption and/or insulative layer  3 , and straps  7  to secure the cover  10  to a solar panel  4 . The solar panel  4  is shown only schematically in  FIG. 3  The rigid cover  10  is used preferably on a solar panel that is a flat-plate type panel. Water-conducting tubes lead into and out of the conventional solar panel and flaps or openings  5  are provided on the side walls of the outer shell  1  to accommodate these tubes. The straps  7  include corner straps  6  and/or a long strap  7 A that extends across the underside of the solar panel  4 . The outer shell or layer  1  is ideally constructed of a material that is rot and mildew resistant, such as a lightweight manufactured material, including a metallic material. The shock-absorbing or insulative layer  3  is preferably constructed of a foam or other compressible material. The outer layer  1  and the insulative layer  3  may be laminated to each other, to provide a single fabric. It is also possible to use a material that combines both desired properties, i.e., weather resistance and heat insulation, to form the covers  10 ,  20 . 
         [0022]      FIGS. 4-6  illustrate a second embodiment of a solar panel cover  20  that is a soft cover that is particularly well suited to fit over solar panels that are arrays of evacuated tubes. The cover  20  comprises an outer shell  21  and a shock-absorption or insulative layer  22  and is manually removable from the solar panel  4 . The outer shell  22  is ideally constructed of a flexible fabric, such as canvas or other flexible fabric that is rot and mildew resistant. The shock-absorption layer  22  is a layer of foam or other compressible material. The outer shell  21  may be secured to the solar with straps  7  similar to those described in connection with the cover  10 . It may also, instead of the straps  7 , have an elastic edge  21 A that allows the fabric to fit around the solar panel  4  and enclose the edges of the panel so as to secure the cover  20  to the panel  4 . 
         [0023]    The outer shells  1 ,  21  may be constructed of or coated with a reflective material to reduce the solar radiation that impinges on the cover. 
         [0024]      FIG. 7  is a perspective view of a third embodiment  30  of a solar panel cover according to the invention for the solar panel  4 . The cover is constructed of a rollable material  32 , such as, for example, a flexible sheet fabric or a system of slats that allow the cover  30  to roll up or fold up with pleats. A storage enclosure  34  is provided, for receiving the rolled-up or pleated portion of the cover  30 . The mechanism for moving the cover  30  between a deployed or closed position and a non-deployed or open position is a conventional mechanism, such as is used for electrically operating large awnings, and is not shown in any detail. The mechanism may be manually operated or motor-driven. Ideally, the mechanism is motor-driven with an operating switch that is conveniently located for easy access. The cover  30  has sides  32 A that are captured in a track  36 . The mechanism for rolling and unrolling the cover forces the sides  32 A along the track  36 , so as to cover or uncover the solar panel  4  as desired. The flexible sheet fabric may be stitched at regular intervals to facilitate pleating. Preferably, the cover  30  includes an outer surface that is weather-resistant and heat-insulative properties. The cover may comprise an outer weather-resistant layer and an inner heat-insulative layer, or be constructed of a material that combines both desired properties. 
         [0025]      FIGS. 8-10  illustrate a fourth embodiment  40  of a solar cover according to the invention for the solar panel  4 . This embodiment includes a series of cover vanes or segments  42  that are mounted on a linkage system  46 , so as to be movable from an open position, shown in  FIGS. 8 and 9  and a closed position, shown in  FIG. 10 . The cover includes a motor-driven linkage system  46  that is coupled with the segments  42 . The linkage system  46  includes a pair of linkage rods, a first rod  46 A and a second rod  46 B, each of which are connected to the segments  42  as shown in  FIG. 9 . The first rod  46 A is connected to an outer portion  46 C and the second rod to a center portion  46 D of each segment  42 . A motor M drives the linkages so as to shift the segments  42  between an open and a closed position. In the embodiment shown, the motor M is enclosed in protective enclosure  44 . The segments  42  may be constructed of a sheet metal or plastic material. As with the other embodiments of the cover described herein, the outer surface or shell of the segments  42  may be constructed of a weather-resistant material and the inner portion or inner shell be constructed of a material that provides the desired insulative properties to block excessive solar radiation and prevent the solar panel from overheating. 
         [0026]    Sensors may be used with any motor-driven system to move the cover between the deployed and non-deployed positions, depending on weather conditions. For example, a temperature sensor  50 , shown in  FIG. 7 , may be coupled with any motor-driven means for moving the cover, to close the cover when the temperature on the solar panel exceeds a threshold value and/or to open the cover when the temperature drops below a certain value. Shock sensors may be used in areas that are prone to severe hail storms, to close the cover when impact forces that exceed a predetermined threshold value impinge on the solar panel. 
         [0027]    The foregoing is considered as illustrative only of the principles of the invention. The dimensional relationships for the covers  10 ,  20 ,  30 ,  40  include variations in size, materials, shape, form, function and manner of operation, assembly and use. All equivalent relationships to those illustrated in the drawings and described in the specification are included in the scope of the present invention.