Abstract:
A solar defrost panel has a photovoltaic panel with an integrated electrical defrost system. The electrical defrost system has an electrical heating element that overlays the photovoltaic panel. The electrical defrost system can remove snow, frost and ice from the solar defrost panel and prevent snow, frost and ice from accumulating on the solar defrost panel. The electrical defrost system can have a controller to automatically or manually control operation of the electrical heating element. The controller can be located inside of a building for convenience of the user. The solar defrost panel provides clearing of snow, frost and ice from the solar defrost panel which can allow the photovoltaic panel to operate effectively during winter and in cold climate regions.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to solar panels. More specifically, this invention relates to solar panels having a defroster or solar defrost panels. Embodiments of the present invention provide a solar defrost panel which can melt snow, frost and ice on the solar panel which allows the solar panel to be more useful in cold climates. The present invention also pertains to related methods, including methods of operating solar defrost panels and methods of making solar defrost panels. At least one embodiment of the present invention is described in the context of a solar defrost panel. However, the present invention is not limited to a particular embodiment and may be practiced in other embodiments, as well. 
         [0002]    Solar panels are well known and commonly used to convert solar energy to electrical energy. Solar panel technology has advanced greatly during the last few decades. However, existing solar panels have limitations and can be improved. For example, solar panels may have limitations as a source of renewable energy in some regions of the world. In colder climate regions, snow, frost and ice can accumulate on the solar panels and reduce or even eliminate sunlight from reaching the photovoltaic cells. Accordingly, the solar panel&#39;s ability to produce electricity can be reduced or even eliminated. The problems associated with snow, frost and ice build-up on solar panels can be worse when the winter season is relatively long or harsh. Large amounts of snow, the frequency of snow fall and low temperature climates can also worsen the problems with snow, frost and ice build-up on solar panels. Furthermore, the duration of sunlight hours during the day can be limited for colder climate regions and solar panels need to be used more effectively during the limited available daylight. 
         [0003]    Solar panels have been cleared of snow, frost and ice by waiting until sunlight warms the solar panel and melts the snow, frost and ice. Also, one could wait until the ambient temperature increases above freezing to melt the snow, frost and ice. Obviously, these methods of removing snow, frost and ice from solar panels can be time consuming, ineffective and may not even work for extended periods of time, e.g., days, weeks or even months. 
         [0004]    Existing solar panels have also been manually cleared of snow, frost and ice. Manually clearing solar panels of snow, frost and ice requires one to frequently battle nature whenever the build-up occurs. In cold climate regions, one may have to repeatedly manually clear snow, frost, and ice buildup from the solar panel systems. Manual clearing of snow, frost and ice from solar panels can be time consuming, inefficient and expensive. Also, solar panels are frequently located in difficult to reach places, such as on rooftops. The safety of a person who must be on a rooftop or ladder during cold, snow and ice conditions to manually clear the snow, frost, and ice from the solar panels can be a significant concern. 
         [0005]    Thus, needs exist for new solar panels, such as solar defrost panels, for the reasons mentioned above and for other reasons. It would be an improvement to provide a new solar panel having a defroster. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides new solar defrost panels. The solar defrost panels have a heater that can remove snow, frost and ice from the solar defrost panels. The present invention also provides new heaters or defroster units which can be included in a solar panel to remove snow, frost and ice from the solar panel. 
         [0007]    The term “defrost” is used in relation to the present invention. The term “defrost” is not limited to removing only frost. The term “defrost” also contemplates removing snow, ice and other frozen liquids. The term “defrost” as it relates to the present invention can also contemplate increasing the temperature sufficiently to remove snow, frost, ice or other frozen liquid. 
         [0008]    Embodiments of the solar defrost panel have an integrated electrical defrost system that overlays solar photovoltaic cell panels or other sun collecting solar panels. The electrical defrost system has a series of electrically conductive grid lines (such as metallic grid lines) that heat up when electric current passes through the grid lines. The increase in temperature prevents snow, frost and ice build up on the surface the solar panels and melts snow, frost and ice which has already been deposited on the solar panel. 
         [0009]    The solar defrost panel may have a controller which controls operation of the electrical defrost system. The controller can automatically operate the electrical defrost system, for example, the controller can be set to automatically turn on the electrical defrost system before sunrise so that the solar defrost panels are clear of snow, frost and ice upon sunrise. The electrical defrost system can also be operated on an on-demand basis as needed. Also, the electrical defrost system can be operated or controlled from inside of a building. 
         [0010]    In an embodiment of the present invention, a solar defrost panel has an energy converter that converts solar energy to electrical energy, and an electrical heater adjacent the energy converter such that a temperature of at least a portion of the solar defrost panel is increased when the electrical heater is electrically actuated. 
         [0011]    The electrical heater may be an electrical resistance heating element. 
         [0012]    The electrical heater may have a transparent panel and an electrical resistance heating element on a side of the transparent panel facing the energy converter. 
         [0013]    The energy converter may have a photovoltaic panel which has a solar exposure side, and a first transparent panel above the solar exposure side of the photovoltaic panel. The electrical heater may have an electrical resistance heating element above the first transparent panel, and a second transparent panel above the electrical heating resistance element. 
         [0014]    The solar defrost panel may further have a controller operatively connected to the electrical heater and controlling an operation of the electrical heater. 
         [0015]    The electrical heating resistance element may have a plurality of elongated electrically conductive elements electrically connected together by bus bars. 
         [0016]    The solar defrost panel may further have a battery electrically connected to an electrical output of the energy converter, and the battery may be electrically connected to the electrical heater. 
         [0017]    In an embodiment of the present invention, a solar defrost panel has a photovoltaic panel having a solar exposure side, an electrical conductive heating element above the solar exposure side of the photovoltaic panel, an electrical insulator between the photovoltaic panel and the electrical conductive heating element, and a first transparent panel above the electrical conductive heating element. 
         [0018]    The solar defrost panel may further have a second transparent panel between the solar exposure side of the photovoltaic panel and the electrical conductive heating element. The second transparent panel may be the electrical insulator. 
         [0019]    The electrical conductive heating element may have a plurality of elongated electrically conductive elements electrically connected together by bus bars. 
         [0020]    The solar defrost panel may further have a controller connected to the electrical conductive heating element and controlling operation of the electrical conductive heating element. 
         [0021]    The solar defrost panel may further have a battery electrically connected to an electrical output of the photovoltaic panel, in which the battery electrically powers the electrical conductive heating element during a battery power mode. 
         [0022]    The electrical conductive heating element may be electrically connected to an electrical output of the photovoltaic panel. 
         [0023]    The solar defrost panel may further have an AC to DC converter in which a DC output of the AC to DC converter is electrically connected to the electrical conductive heating element. 
         [0024]    In an embodiment of the present invention, a solar panel defroster has a flat transparent panel, an electrical conductive heating element adjacent the flat transparent panel, and a frame around an outer edge of the flat transparent panel. 
         [0025]    The electrical conductive heating element may have a plurality of elongated electrically conductive elements electrically connected together by bus bars. 
         [0026]    In an embodiment of the present invention, a method of heating a solar panel provides supplying electric current to an electrical conductive heating element, increasing a temperature of the electrical conductive heating element by the electric current passing through the electrical conductive heating element, and transferring heat energy from the electrical conductive heating element to at least a portion of the solar panel. 
         [0027]    The step of transferring heat energy may provide transferring heat energy to an outermost solar exposure portion of the solar panel. 
         [0028]    The step of supplying electric current may provide supplying electric current from a battery. The battery may be recharged with electrical output from the solar panel. 
         [0029]    The step of supplying electric current may provide supplying electric current from an AC to DC converter. 
         [0030]    The method of heating a solar panel may further provide controlling operation of the electrical conductive heating element with a programmable controller. 
         [0031]    In an embodiment of the present invention, a method of operating a defroster of a solar panel may provide turning on an electrical heater of the solar panel, increasing a temperature of at least a portion of the solar panel with the electrical heater, and melting frozen water on the solar panel with the portion of the solar panel having the increased temperature. 
         [0032]    The method of heating operating a defroster of a solar panel may further provide controlling operation of the electrical heater with a programmable controller. 
         [0033]    In an embodiment of the present invention, a method of making a solar defrost panel provides overlaying an electrical heater layer on top of a solar energy to electrical energy converter. 
         [0034]    The overlaying step may further provide overlaying a transparent panel carrying an electrical heater on top of the solar energy to electrical energy converter. 
         [0035]    The method of making a solar defrost panel may further provide assembling the electrical heater layer and the solar energy to electrical energy converter together within a frame. 
         [0036]    The overlaying step may further provide retrofitting the electrical heater layer onto a solar panel having the solar energy to electrical energy converter. 
         [0037]    An advantage of the solar defrost panel can be that the electrical defrost system removes snow, frost and ice from the solar defrost panel. 
         [0038]    Another advantage of the solar defrost panel can be that snow, frost and ice does not have to be manually removed from the solar defrost panel. 
         [0039]    Another advantage of the solar defrost panel can be to increase the usage and efficiency of the solar defrost panel during the winter season. 
         [0040]    A further advantage of the solar defrost panel can be to use solar defrost panels in cold climate regions. 
         [0041]    Yet another advantage of the present invention can be to retrofit existing solar panels with the electrical defrost system. 
         [0042]    Another advantage of the present invention can be to remove snow, frost and ice from solar defrost panels without having to climb on a ladder or a roof to manually clear solar panels during winter. 
         [0043]    Embodiments of the present invention may have various features and provide various advantages. Any of the features and advantages of the present invention may be desired, but, are not necessarily required to practice the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0044]      FIG. 1  is a top perspective view of a solar defrost panel according to the present invention. 
           [0045]      FIG. 2  is a bottom perspective view of the solar defrost panel of  FIG. 1 . 
           [0046]      FIG. 3  is an exploded perspective view of the solar defrost panel of  FIG. 1 . 
           [0047]      FIG. 4  is a top perspective view of an electrical heating element and a transparent panel of the solar defrost panel of  FIG. 1 . 
           [0048]      FIG. 5  is a top perspective view of the electrical heating element and the transparent panel of  FIG. 4  on a solar panel. 
           [0049]      FIG. 6  is a bottom perspective view of the electrical heating element, the transparent panel and the solar panel of  FIG. 5 . 
           [0050]      FIG. 7  is an enlarged partial view of  FIG. 5 . 
           [0051]      FIG. 8  is an enlarged partial view of  FIG. 6 . 
           [0052]      FIG. 9  is a schematic diagram a solar defrost panel array electrically connected to a control panel. 
           [0053]      FIG. 10  is an enlarged schematic diagram of the control panel of  FIG. 9 . 
           [0054]      FIG. 11  is a schematic diagram of the control panel connected to battery power. 
           [0055]      FIG. 12  is a schematic diagram of the control panel connected to AC power. 
           [0056]      FIG. 13  is a top perspective view of a solar panel defroster according to the present invention. 
           [0057]      FIG. 14  is a bottom perspective view of the solar panel defroster of  FIG. 13 . 
           [0058]      FIG. 15  is an exploded perspective view of the solar panel defroster of  FIG. 13 . 
           [0059]      FIG. 16  is an enlarged partial view of the solar panel defroster of  FIG. 13 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0060]    One example of a solar defrost panel  10  according to the present invention is shown in  FIGS. 1-3 .  FIG. 1  shows a top view of the solar defrost panel  10 ,  FIG. 2  shows a bottom view of the solar defrost panel  10  and  FIG. 3  shows and exploded view of the solar defrost panel  10 . The solar defrost panel  10  has a solar panel layer  12 , a transparent panel  14 , an electrical heating element or electrical heater  16 , a transparent panel  18  and a frame  20 . 
         [0061]    The solar panel layer  12  has a plurality of photovoltaic cells  22  arranged in an array. The solar panel layer  12  has a solar exposure side  24  facing upward as viewed in  FIG. 3 . The solar panel layer  12  is bonded to the bottom side  26  of the transparent layer  14 . The solar panel layer  12  and the transparent layer  14  together can be considered a solar panel. The photovoltaic cells  22 , the solar panel layer  12  and the transparent panel  14  (the solar panel) can be existing components as known in the solar panel technology field. For example, the photovoltaic cells  22  can be wafers, thin films, and nanocells, etc. However, the present invention can be practiced with new solar panel technology as such technology becomes available. The solar panel layer  12  converts solar energy (sunlight) to electrical energy. The present invention can also be practiced with other energy converters that convert solar energy to electrical energy, including current and future technologies. 
         [0062]    In the illustrated embodiment of the present invention, the electrical heating element  16  is an electrical resistance heating element. When electrical power is supplied to the electrical heating element  16 , the electrical heating element  16  generates heat. The heat generated by the electrical resistance heating element  16  increases the temperature of the transparent panel  18  which removes snow, frost and ice from the solar defrost panel  12 . The electrical heating element  16  can provide rapid heating, particularly when connected to a relatively high amperage circuit. 
         [0063]    The electrical heating element  16  has a plurality of elongated electrically conductive elements  28  electrically connected together by electrically conductive bus bars  30 ,  32 ,  34 . The electrical heating element  16  has leads  36 ,  38  for supplying electrical power to the electrical heating element  16 . Referring also to  FIG. 4 , the electrical heating element  16  has a zigzag grid pattern with the elongated elements  28  extending parallel along the longer length of the transparent panel  18  and the bus bars  30 ,  32 ,  34  extending along the shorter width of the transparent panel  18 . The electrical heating element  16  extends over substantially all of the surface of the transparent panel  18  to effectively heat substantially all of the transparent panel  18 . Although a particular grid pattern of the electrical heating element  18  is shown in  FIGS. 1 ,  3  and  4 , the present invention can be practiced using other grid patterns as well. 
         [0064]    The elongated heating elements  28  of the electrical heating element  16  can be made of any suitable material that generates heat when subjected to electrical current. It may be beneficial for the elongated heating elements  28 , and the electrical heating element  16  itself, to have good electrical conductive properties and good heat generating properties at lower temperatures, such as temperatures below freezing. Some examples of suitable materials for the electrical heating element  16  include, without limitation, coppers, metallic films, aluminums, conductive coating platings, silver ceramic compounds, conductive inks, thermoplastic films, conductive metallic pastes, soldiers, synthetic metals, silver inks, silver pastes, other materials and combinations thereof. 
         [0065]    The bus bars  30 ,  32 ,  34  of the electrical heating element  16  can be made of any suitable material that conducts electricity to the elongated elements  28 . The bus bars  30 ,  32 ,  34  may also generate heat when subjected to electrical current, if so desired. It may be beneficial for the bus bars  30 ,  32 ,  34  to have good electrical conductive properties and good heat generating properties at lower temperatures, such as temperatures below freezing. Some examples of suitable materials for the bus bars  30 ,  32 ,  34  include, without limitation, aluminums, coppers, brasses, copper clad aluminums, synthetic metals, conductive coating platings, silvers, solid materials, laminated materials, flat flexible materials, wave crimp cables, other materials and combinations thereof. 
         [0066]    Referring to  FIGS. 1 ,  3  and  4 , the electrical heating element  16  can be attached to the transparent panel  18 , particularly, attached to a bottom surface  40  of the transparent panel  18 . The transparent panel  18  and the electrical heating element  16  are positioned above the solar panel layer  12 , i.e., overlay the solar panel layer  12  on the top side (solar exposure side  24 ) of the solar panel layer  12 . The electrical heating element  16  can be attached to the transparent panel  18  in any suitable manner. An advantage to attaching the electrical heating element  16  to the transparent panel  18  is that the electrical heating element  16  and transparent panel  18  assembly can be placed on top of or overlay an existing solar panel to form the solar defrost panel  10 . 
         [0067]    However, the present invention can be practice using other structures as well. For example, one alternative would be to attach the electrical heating element  16  to the top surface  42  of the transparent panel  14 . Another alternative would be not to attach the electrical heating element  16  to either of the transparent panels  14 ,  18 , but rather, hold the electrical heating element  16  in place between the two transparent panels  14 ,  18 , for example by pressure or by bonding the transparent panels  14 ,  18  to each other. Further alternatives would be to imbed the electrical heating element  16  in the material of the transparent panel  18  or the transparent panel  14 , i.e., encase the electrical heating element  16  in the material of either transparent panel  14 ,  18 . 
         [0068]    The electrical heating element  16  is electrically conductive as are the photovoltaic cells  22  of the solar panel layer  12 . The photovoltaic cells  22  of the solar panel layer  12  and the electrical heating element  16  should be electrically insulated from each other to avoid an electrical short between them. The transparent panel  14  provides electrical insulation between the solar panel layer  12  and the electrical heating element  16 . Similarly, the transparent panel  18  also covers and electrically insulates the electrical heating element  16 . The electrical heating element  16  can be electrically insulated from other portions of the solar defrost panel  10  by other means than being sandwiched between the two transparent layers  14 ,  18 . For example, the electrical heating element  16  could be coated with an electrical insulator or an electrical insulating film could cover the electrical heating element  16 . One of the transparent panels  14 ,  18  may not be needed by using other means to electrically insulate the electrical heating element  16 . 
         [0069]    The transparent panel  18  can carry the electrical heating element  16  as mentioned above. The transparent panel  18  provides a closed top for the solar defrost panel  12  which protects the solar defrost panel  12  from the environment. The transparent panel  18  can provide extra protection from the outside environment by having an additional layer of tempered glass/high density clear plastic to current solar cell panels. The transparent panel  18  is, of course, transparent to sunlight to allow the sunlight to pass through the transparent panel  18  to reach the solar panel layer  12 . The transparent panel  18  may also have other properties that may be beneficial to the solar defrost panel  12 , for example, without limitation, impact resistant, weather resistant, resistant to degradation from sunlight, electrical insulator, strong, light weight, high density, and heat conductive. The transparent panel  18  conducts heat from the electrical heating element  16  to a top surface  44  of the transparent panel  18  to melt any snow, frost and ice on the solar defrost panel  12 . 
         [0070]    The transparent panel  18  can be made of a wide variety of materials suitable for use in the solar defrost panel  12 . Some examples of suitable materials for the transparent panel  18  include, without limitation, glasses, tempered glasses, annealed glasses, architectural glasses, fire resistant glasses, toughen glasses, tempered laminated glasses, laminated glasses, low-e glasses, plastics, clear plastics, polycarbonates, acrylics, fiberglasses, thermoplastics, plexiglasses, lucites, acetals, and other materials and combinations thereof. Furthermore, although the illustrated embodiment of the present invention shows the transparent panel  18  as a single layer, the transparent panel  18  can have multiple layers, including multiple layers of the same or different materials. 
         [0071]    The sandwich of the transparent panel  18 , the electrical heating element  16  and the transparent panel  14  may form an air gap or pocket between the transparent panels  14 ,  18 . Preferably, the air pocket is sealed closed, for example, the perimeter edges of the transparent panels  14 ,  18  are sealed when sealed to the frame  20 . The electrical heating element  16  heats the air in the air pocket which heats the transparent panel  18  to remove snow, frost and ice from the solar defrost panel  10  or prevent snow, frost or ice from accumulating on the solar defrost panel  10 . The heated air pocket may heat the transparent panel  18  more uniformly and quickly and maintain heat longer after the electrical heating element  16  is turned off. The electrical heating element  16  can also heat the transparent panel  18  directly by being in contact with the transparent panel  18 . 
         [0072]    The frame  20  extends around an outer perimeter of the combined solar panel layer  12 , the transparent panel  14 , the electrical heating element  16  and the transparent panel  18 . The frame  20  holds all of those components of the solar defrost panel  10  together. A seal (not shown), for example an appropriate caulk, can be used around the frame  20  to provide a liquid tight seal between the frame  20  and the combined solar panel layer  12 , the transparent panel  14 , the electrical heating element  16  and the transparent panel  18 . Structures other than the frame  20  can be used to hold the combined solar panel layer  12 , the transparent panel  14 , the electrical heating element  16  and the transparent panel  18  together. Also, any suitable sealing means can be used instead of caulk. The frame  20  can be made of any suitable material, for example, without limitation, aluminums, metals, plastics, other materials and combinations thereof. 
         [0073]    Referring to  FIGS. 5-8 , the solar defrost panel  10  is shown without the frame  20 .  FIGS. 5 and 7  show top views of the solar defrost panel  10  and  FIGS. 6 and 8  show bottom views of the solar defrost panel  10 . The bus bars  30 ,  34  are main power bus bars which are connected to a power source to operate the electrical heating element  16 . As can be seen more clearly in  FIGS. 7 and 8 , the main power buss bar  30  is bent and rapped around from the top side  42  of the transparent panel  14  to the underside  46  of the solar panel layer  12 . The end  48  of the positive main power bus bar  30  is attached to a terminal barrier strip  50  which is attached to the bottom side  46  of the solar panel layer  12 . The positive lead  36  having a fuse holder  52  and a fuse  50  is connected to the terminal barrier strip  50  and to the positive feed from the power supply. The fuse  54  provides a safeguard to the electrical components of the solar defrost panel  10  from damage or overheating. A positive connector lead  56  can also be connected to the terminal barrier strip  50  and to another solar defrost panel  10  as will be more fully described below.  FIGS. 7 and 8  only show the positive main power bus bar  30  and positive terminal barrier strip  50  for electrical connection to the positive terminal of the power supply. The other negative main power bus bar  34  is similarly bent and wrapped around and is electrically connected to a negative terminal barrier strip which is electrically connected to the negative terminal of the power supply. 
         [0074]    Referring to  FIG. 9 , a schematic diagram of a solar defrost panel system  58  is shown. The solar defrost panel system  58  has a first array  60  of solar defrost panels  10  and a second array  62  of solar defrost panels  10 . The solar defrost panel system  58  has a control panel  64  connected to the first and second arrays  60 ,  62  for controlling operation of the electrical heater elements  16  in the solar defrost panels  10 . The control panel  64  is shown in an enlarged schematic diagram in  FIG. 10 . The control panel has a main circuit terminal  66  having positive and negative terminals  68 ,  70  for connection to an electrical power source. A power selector switch  72  can be set to the appropriate power source, AC or DC. The electrical power source can be a DC power, source as the electrical heating elements  16  operate on DC power. Examples of DC power sources include, without limitation, DC batteries (such as DC batteries charged by the solar panel layers  12  or other DC batteries), DC output from the solar panel layer  12 , and DC output from an AC to DC converter.  FIG. 11  shows a schematic diagram of the control panel  64  connected to the DC batteries  74  that are charged by the solar panel layer  12 . The electrical power switch  72  is set to DC power. 
         [0075]    Other embodiments of the present invention could use AC power instead of DC power. For example,  FIG. 12  shows a schematic diagram of the control panel  64  connected to AC power. An AC power adapter  76  is plugged into an AC outlet  78  and plugged into an AC power connection  80  of the control panel  64 . The control panel  64  can have an AC to DC converter (not shown) for converting the AC power to DC power to run the electrical heating elements  16 . The electrical power switch  72  is set to AC power. 
         [0076]    Referring to  FIGS. 10 and 11 , the control panel  64  distributes the DC power from the main circuit terminal  66  to a plurality of circuit breakers  82 . The circuit breakers  82  are connected to the main circuit terminal  66  in series. Each circuit breaker  82  can accommodate one or more solar defrost panels  10 , such as the plurality of solar defrost panels  10  which are connected in series for each solar defrost panel array  60 ,  62 . Referring to  FIGS. 8-10 , the first and second arrays  60 ,  62  of solar defrost panels  10  are connected to individual circuit breakers  82  of the control panel  64 . The positive and negative leads  36 ,  38  connect the circuit breakers  82  to the first and second arrays  60 ,  62  of solar defrost panels  10 . The solar defrost panels  10  in the first and second arrays  60 ,  62  are connected together in series. As shown in  FIG. 9 . 
         [0077]    Referring to  FIGS. 8 and 9 , the positive terminal barrier strip has two positions, one position provides power to the electrical defrost system from the control panel and the second position provides power to the next solar defrost panel  10  in a series circuit. The negative terminal barrier strip has two positions, one position is connected to the negative lead from the control panel. The second position is connected to the negative lead to the next solar defrost panel  10  in a series circuit. If there is just one solar defrost panel  10  or the last solar defrost panel  10  in the series, the second position is to a ground cable. 
         [0078]    Referring to  FIGS. 9 and 10 , the control panel  64  has a controller  84  that controls operation of the electrical heating elements  16 . The control panel  64  also has a user interface connected to the controller  84 , such as a keypad  86  and display  88 , for user interaction with the controller  84 . The control panel  64 , particularly the controller  84 , provides the system functions of operating the electrical heating elements  16 . The controller  84  can manually turn on/off the electrical heating elements  16  in an on-demand mode and automatically turn on/off the electrical heating elements  16  in a program mode. The controller  84  can be programmed to run the electrical heating elements  16  for desired periods of time on particular days, similar to HVAC controllers. The controller  84  can be any control mechanism to control operation of the electrical heating elements  16 , for example, without limitation, printed circuit boards, microprocessors, mechanical timers, mechanical switches and even a simple on/off switch, etc. The control panel  64  can be located close to the solar defrost panels  10  or remotely from the solar defrost panels  10 . Also, the controller  84  and user interface  86 ,  88  of the control panel  64  can be incorporated within the control panel  64  itself or located remotely from the control panel  64 . For example, the controller  84  and user interface  86 ,  88  can be located inside of a building where it is convenient for a user to interface with the controller  84 . 
         [0079]    Referring to  FIGS. 13-16 , another embodiment of the present invention will now be described. In this embodiment, a solar panel defroster  90  is a self contained device which can be added onto an existing solar panel. The solar panel defroster  90  has components which are the same or similar to components shown and described above with reference to  FIGS. 1-12  and are assigned like reference numbers. The solar panel defroster  90  has an electrical heating element  16 , a transparent panel  18  and a frame  92 . 
         [0080]    The electrical heating element  16  is the same as the electrical heating element  16  of the solar defrost panel  10 , except the positive and negative main power bus bars  94 ,  96  may not bend and wrap around as in the solar defrost panel  10 . Rather, the main power bus bars  94 ,  96  may extend from an outer edge  98  of the transparent panel  18  for connection to the positive terminal barrier strip  50  and a negative terminal barrier strip  100 . The transparent panel  18  is the same as the transparent panel  18  in the solar defrost panel  10 . 
         [0081]    The frame  92  of the solar panel defroster  90  may have a structure to surround only the transparent panel  18  rather than all of the layers of the solar defrost panel  10 . The frame  92  may also have brackets or other structures for mounting and securing the solar panel defroster  90  to a solar panel. A seal  102  ( FIGS. 14 and 15 ) may be provided to seal the solar panel defroster  90  against a solar panel. The seal  102  prevents liquids, rain, snow, humidity, dirt, dust and other undesirable materials from entering the space between the solar panel defroster  90  and the solar panel. In the illustrated embodiment, the seal  102  has a shape which conforms to the shape of the frame  92 . The seal  102  can be adhered to the bottom side of the frame  92  for sealing against a solar panel. Of course, the seal  102  could have other shapes and could have sealing contact with other portions of the solar panel defroster  90 . For example, the seal  102  could seal against the transparent panel  18 . The seal  102  can be any type of seal and seal material suitable for its intended purpose, for example, without limitation, rubbers, gaskets, caulks, silicon caulks, etc. 
         [0082]    The solar panel defroster  90  may have various uses. For example, without limitation, the solar panel defroster  90  could be used to retrofit existing solar panels. Also, the solar panel defroster  90  could be a modular option that can be added to solar panels if desired. The solar panel defroster  90  can even be added to solar panels after the solar panels have been installed in the field. 
         [0083]    An embodiment of the present invention has been shown and described as a solar defrost panel having a rectangular shaped solar panel (photovoltaic panel) having a plurality of photovoltaic cells. However, the present invention is not limited to any particular shape, solar panel, photovoltaic panel or photovoltaic cell. The present invention can be practiced with any device that converts solar energy (sunlight) to another form of energy, such as electrical energy. 
         [0084]    It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.