Abstract:
The photovoltaic panel cleaning machine is installed upon a linear array of photovoltaic (solar) panels, automatically operating periodically to remove any dust, debris, and/or light condensation from the panels to optimize their efficiency. The machine is driven back and forth along tracks extending along opposite edges of the panel array, and receives electrical power from a storage battery charged by the solar panel array. The machine includes an air compressor, a blower and nozzles that blow dust and debris from the solar panels, and two different roller brushes. Air is blown over the panels on the first pass, and the machine then reverses direction to apply a first roller to the panels for further debris removal on a second pass. A third pass is made using the air blower, and the direction reverses once again, the second roller being applied on the fourth pass to statically attract any remaining debris.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to photovoltaic or solar panels, and particularly to an automated photovoltaic panel cleaning machine for periodically removing dry dust, debris, and/or moisture condensation from photovoltaic (solar) panel arrays. 
     2. Description of the Related Art 
     The harvesting or gathering of solar energy by means of photovoltaic (pv) panels, also known as solar panels, has become increasingly popular in response to the depletion of petroleum resources and their corresponding costs, as well as the desire to reduce atmospheric and other forms of pollution. While solar panels are still relatively costly, the cost of production of such panels has been decreasing and the efficiency of such panels has been increasing with advances in technology. This has resulted in the cost-effective installation of solar panels in many areas of the world, particularly in relatively dry and cloudless regions near the equator where maximum solar energy may be received by such panels. 
     One perennial problem with such solar panel installations is that such dry areas are subject to a relatively large amount of wind-blown dust, sand, and other debris. This can result in the relatively rapid deposition of a thin layer of relatively opaque material covering the energy receiving surfaces of a solar panel array. It has been found that the energy gathering efficiency of photovoltaic (pv, or solar) panels can be degraded on the order of fifty percent in a relatively short span of time by wind-blown dust and debris, depending upon the strength and direction of the wind and the nature of the soil and ground cover upwind of the solar panel array. Strong winds can create dust storms and sandstorms that may carry dust and sand a considerable distance, perhaps up to a hundred miles or more, to cover exposed articles (such as solar panels) with debris. 
     Another concern is the accumulation of condensation particles (i.e., dew and frost) on solar panels as the temperature reaches the dew point at night, even in drier climates. While frost will generally melt soon after sunrise at lower elevations and latitudes before the sun reaches an angular elevation sufficient for efficient energy production, there may still be some liquid moisture remaining on the solar panels until the air warms sufficiently to evaporate the moisture, particularly if there is little difference between the ambient temperature and the dewpoint. It is desired that any moisture be removed from the solar panels some time before the sun reaches an elevation sufficient to efficiently produce electrical power, in order to optimize the reception of sunlight by the panels. 
     Thus, a photovoltaic panel cleaning machine solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The photovoltaic panel cleaning machine provides for the automated cleaning of photovoltaic (PV, or solar) panels using both pneumatic blowing and mechanical brushing or scrubbing to remove accumulated dust, sand, and/or other debris from the panels. The machine incorporates a small air compressor to supply the required air. The air is dispensed from nozzles along a tube that extends across the solar panels. A photocell senses when there is adequate sunlight to warrant operation of the solar panels, i.e., to determine their need for cleanliness. When the photocell senses sufficient sunlight, a timer is actuated to delay the start of the cleaning operation to an optimum time. A hygrometer detects latent humidity to determine whether conditions are correct for operation of the device, i.e., there is no appreciable moisture disposed upon the solar panels. Alternatively, the operating system of the machine may be programmed to blow dry some slight accumulation of moisture on the panels. The machine is advanced along the length of the elongate solar panel array by a plurality of motorized wheels traveling in tracks or rails installed along each edge of the solar panel array. 
     When the panels have been determined to be dry, the machine rotates the pneumatic blower tube away from the panel surface while simultaneously rotating a foam plastic roller in contact with the panel. The roller is motorized so that the roller surface advances in the direction of travel of the machine along the solar panels, i.e., there is relative motion between the contact surface of the roller and the panels during operation as the apparatus reverses direction and travels back along the length of the solar panel array. This removes most, if not all, solid particles remaining after the air blowing operation. 
     The foam plastic roller is then rotated away from the surface of the panels, and the pneumatic blower tube is simultaneously rotated once again adjacent to the panel surface. The direction of travel is reversed once again, with the machine proceeding along the length of the panel array in its original direction of travel while blowing any remaining material from the panel surface. 
     Finally, the roller and blower assembly is rotated to position a second roller in contact with the surface of the solar panel array. This second roller incorporates a synthetic fiber material that generates a static electrical charge as it brushes against the surface of the panels. This static charge attracts any remaining dust and/or particulate debris from the panel surface as the machine reverses its direction once again to return to its original starting position at one end of the panel array. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental side elevation view of a photovoltaic panel cleaning machine according to the present invention, as installed upon an array of photovoltaic panels. 
         FIG. 2  is a detailed environmental perspective view of the photovoltaic panel cleaning machine according to the present invention, illustrating further features thereof. 
         FIG. 3  is a detailed environmental side elevation view of the photovoltaic panel cleaning machine according to the present invention, illustrating further features thereof. 
         FIG. 4  is an environmental end elevation view of the photovoltaic panel cleaning machine according to the present invention, illustrating further features thereof. 
         FIG. 5  is a block diagram showing the electrical components of the photovoltaic panel cleaning machine according to the present invention. 
         FIG. 6  is a flowchart briefly describing the steps in the operation of the photovoltaic panel cleaning machine according to the present invention. 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The photovoltaic panel cleaning machine provides for the automatic cleaning of a linear array of photovoltaic (PV, or solar) panels without the use of water or other liquids, thus obviating the need to provide a supply of such liquids. This is particularly valuable in dry environments where such PV or solar panels are often deployed in order to maximize their exposure to sunlight. 
       FIG. 1  of the drawings is an environmental side elevation view of a linear array of PV or solar panels P, showing the panel cleaning machine  10  movably installed thereon. The solar panel array P includes laterally opposed first and second tracks  12  and  14 , respectively. One of the tracks  1 ,  14  is disposed along each of the opposite lateral edges of the panel array P. The tracks  12  and  14  extend somewhat beyond the opposite ends of the PV panel array P as shown in  FIG. 1 , so the machine  10  does not shade the PV panels when the machine  10  is parked and/or reverses its direction of travel after each pass over the panels P. Each track  12 ,  14  comprises an upper rail and a lower rail spaced apart from the upper rail. Track  12  has upper and lower rails  12   a  and  12   b , and track  14  has upper and lower rails  14   a  and  14   b . Each of the rails  12   a ,  12   b ,  14   a , and  14   b  comprises a generally U-shaped section, the upper rails  12   a ,  14   a  being inverted. The two rails  12   a ,  12   b  and the two rails  14   a ,  14   b  are spaced apart from one another by substantially vertical ties  16 . This configuration is shown most clearly in  FIG. 4  of the drawings. 
     The panel cleaning machine  10  includes a first pair of drive and guide wheels  18   a  captured between the first track rails  12   a  and  12   b , and a second pair of drive and guide wheels  18   b  captured between the second track rails  14   a  and  14   b . At least one of the wheels  18   a ,  18   b  of each wheel pair is driven by a drive motor  20   a ,  20   b , respectively, for each wheel pair, as shown in  FIG. 4 . The motors  20   a ,  20   b  extend laterally inward from the lower edges of respective drive brackets  22   a  and  22   b , disposed laterally outboard of the tracks  12 ,  14  and wheels  18   a ,  18   b . A plate support arm  24   a  and  24   b , respectively, extends upward from its respective drive bracket  22   a ,  22   b.    
     The upper end of each of the plate support arms  24   a ,  24   b  has a plate  26   a ,  26   b , respectively, rotationally or pivotally secured thereon and parallel to one another. A drive motor  28 , most preferably a stepper motor, extends inboard from the upper end of the first plate support arm  24   a  to rotate the first plate  26   a  thereon. As the two plates  26   a  and  26   b  are tied together by various panel cleaning elements, as described further below, the second plate  26   b  rotates in unison with the first plate  26   a  when the motor  28  is activated. 
     Each plate  26   a ,  26   b  preferably has a triangular configuration, and most preferably an equilateral triangular configuration, and defines three corresponding apices. The first apices of the two plates  26   a ,  26   b  are designated as apices  30   a  and  30   b  and have a pneumatic blower tube  32  extending therebetween. The tube  32  includes a plurality of holes  34  therein to expel compressed air therefrom to blow dust and debris from the PV panels P when the machine  10  is in operation. The second apices  36   a ,  36   b  have a first cleaning element comprising a first roller  38  extending therebetween. The first roller  38  is driven rotationally by a first cleaning element drive motor  40 . This first roller  38  is preferably covered by a synthetic foam plastic material, e.g., polyurethane. The third apices  42   a ,  42   b  ( FIG. 4 ) have a second cleaning element comprising a second roller  44  extending therebetween. The second roller  44  is driven rotationally by a second cleaning element drive motor  46  ( FIG. 4 ). The second roller  44  is preferably covered by a synthetic wool fiber material to generate dust-attracting static electricity as it rubs against the surface of the PV panels P. The movable components of the above-described machine  10 , i.e., wheels, motors, brackets, plates, and cleaning elements, comprise a frame for the machine  10 . The frame selectively translates or travels along the length of the linear array of photovoltaic panels P to clean those panels periodically, as required. 
     The automated operating system for the PV panel cleaning machine  10  is shown by means of a block diagram in  FIG. 5  of the drawings. The machine  10  receives electrical power from the PV panel array P. This electrical power may charge an electrical storage battery  48  within the frame or machine  10 . Electrical power from the battery  48  is controlled by a microcontroller  50  via conventional relays and circuitry. The microcontroller  50  communicates with various other components to operate the system, as described below. 
     Initially, the machine  10  is stopped or parked at one end or the other of the two tracks  12  and  14  that extend somewhat beyond the solar panel array P in order to remain clear of the panels. This start position is indicated as step  100  in the flowchart of  FIG. 6 . A photocell  52  senses when there is adequate sunlight to warrant operation of the solar panels P, i.e., to determine their need for cleanliness. If it is dark, then there is no need to deplete the electrical power from the storage battery  48  to operate the machine  10 , since the PV panels P cannot generate any practicable electrical energy in such conditions, whether they be clean or obscured by dust and debris. 
     When the photocell  52  senses sufficient sunlight, a timer  54  ( FIG. 5 ) is actuated to delay the start of the cleaning operation to an optimum time, as indicated by the second step  102  of  FIG. 6 . A hygrometer  56  detects latent humidity to determine whether conditions are correct for operation of the device, i.e., there is no appreciable moisture disposed upon the solar panels, as indicated by the third step  104  of  FIG. 6 . Alternatively, the operating system of the machine  10  may be programmed to blow-dry some slight accumulation of moisture on the panels by means of the pneumatic blower tube  32 . In any event the plates  26   a ,  26   b  are rotated to position the pneumatic tube  32  adjacent the surface of the panels P, as indicated by the fourth step  106  of  FIG. 6 , either to blow any condensation from the surface of the panels P or to blow dry dust and debris from the panel P surface. This is indicated by the “Initiate Stage 1” step  108  in  FIG. 6 . This initialization causes the onboard air compressor or pump  58  ( FIGS. 1 ,  3 , and  5 ) to begin operation and the blower tube  32  with its air jet nozzles or holes  34  to be deployed adjacent the panel surface if this has not previously been done, as indicated by the seventh and eighth steps  112  and  114  of  FIG. 6 . The onboard compressor  58  receives electrical energy from the battery  48  according to programming from the microcontroller  50  for its operation. 
     The machine  10  is advanced along the length of the elongate solar panel array P by the motorized wheels  18   a ,  18   b  traveling in their respective tracks  12  and  14  installed along each edge of the solar panel array P, generally as indicated by the ninth step  116  of  FIG. 6 . The tracks  12  and  14  communicate electrically with the solar panels P to receive electrical power, which is passed to the drive motors  20   a ,  20   b  through their metal wheels  18   a ,  18   b , as is well known in the field of electrically powered rail vehicles. The machine  10  continues to travel the entire length of the panel P array while simultaneously blowing moisture or dust and debris from the surface of the panels P, as indicated by the tenth step  118  of  FIG. 6 . As the machine  10  approaches the opposite end of the panels P, the machine  10  detects a first proximity switch  60  ( FIG. 1 ) that signals the machine  10  to slow its operation as it approaches the end of the tracks  12  and  14 . The machine  10  proceeds at a slower speed until it reaches the second proximity switch  62  ( FIG. 1 ) installed just beyond the end of the panels P, causing the machine  10  to shut down the onboard compressor  58 , as indicated by the eleventh step  120  of  FIG. 6 , and to stop just beyond the PV panels P. 
     When the panels P have been determined to be dry or the initial dust and debris have been blown off, the machine  10  initiates “stage 2” of the operation (twelfth step  122  of  FIG. 6 ) by rotating the pneumatic blower tube  32  away from the panel P surface, while simultaneously rotating the foam plastic roller  38  into position contacting the surface of the PV panels P, generally as indicated by the thirteenth step  124  of  FIG. 6 . The foam plastic roller  38  and the fiber roller  44  are larger in diameter than the blower tube  32 , so the rollers  38  and  44  actually contact the panel P surface to mechanically remove particulate matter. The wheel drive motors  20   a  and  20   b  are reversed to drive the machine  10  back in the opposite direction from its first stage operation, generally as indicated by the fourteenth step  126  of  FIG. 6 . The roller  38  is rotated by its drive motor  40  so that the roller surface advances in the direction of travel of the machine along the solar panels P, i.e., there is relative motion between the contact surface of the roller  38  and the panels P during operation as the apparatus  10  reverses direction and travels back along the length of the solar panel array P. This removes most, if not all, of the solid particles remaining after the air-blowing operation. 
     A third proximity switch  64  is located just short of the end of the panels P, generally opposite the first proximity switch  60 , as shown in  FIG. 1 . The operation is substantially the same as described above for the first proximity switch  60 , i.e., this third switch signals the machine  10  to slow as it approaches the ends of the tracks  12  and  14 . The machine  10  continues to slowly move along the tracks and beyond the end of the panel P until it encounters the fourth proximity switch  66 , whereupon the machine  10  stops to ready itself for the third stage of the operation as indicated by the sixteenth step  130  of  FIG. 6 . The foam plastic roller  38  is then rotated away from the surface of the panels P, and the pneumatic blower tube  32  is simultaneously rotated once again adjacent to the panel P surface and the compressor or air pump  58  is once again started, generally as indicated by the seventeenth and eighteenth steps  132  and  134  of  FIG. 6 . The direction of travel is reversed once again, as indicated by the nineteenth step  136  of  FIG. 6 , so that the machine  10  proceeds along the length of the panel P array in its original direction of travel while blowing any remaining material from the panel P surface, in accordance with the twentieth step  138  of  FIG. 6 . This operation continues until the machine again encounters the first and second proximity switches  60  and  62  to once again slow and stop the machine  10  and shut down the onboard compressor  58 , generally as indicated by the twenty-first step  140  of  FIG. 6 . Thus, the sixteenth through twenty-first steps  130  through  140  are substantially the same as the corresponding seventh through twelfth steps  112  through  120 , described further above. 
     Finally, the machine  10  initiates “stage 4” of the operation by rotating the roller and blower assembly to position the second roller  44  in contact with the surface of the solar panel array P, as indicated by the twenty-second and twenty-third steps  142  and  144  of  FIG. 6 . This second roller  44  incorporates a synthetic fiber material that generates a static electrical charge as it brushes against the surface of the panels P. As in the case of the first (foam) roller  38 , the drive motor  46  rotates the roller  44  so that its contact with the panel P surface is opposite the direction of travel of the machine  10 , i.e., there is a difference in velocity between the rotating surface of the roller  44  and the panel P surface. The resulting static charge attracts any remaining dust and/or particulate debris from the panel P surface as the machine  10  reverses its direction once again to return to its original starting position at one end of the panel array, generally as indicated by the twenty-fourth and twenty-fifth steps  146  and  148  of  FIG. 6 . 
     When the machine  10  again reaches the third and fourth proximity switches  64  and  66 , the microcontroller  50  will proceed to shut down the operation until the machine  10  is needed again. The process repeats beginning with the first (start) step  100  of  FIG. 6 , and continues once again as described above. The result is a clean PV panel P array capable of optimizing electrical power production. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.