CROSS REFERENCE

[001] This application claims priority from US provisional patent serial number 62/359955 filing date July 8, 2016, which is incorporated herein in its entirety. FIELD OF THE INVENTION

[002] The present disclosure relates to the field of surface cleaning devices.

BACKGROUND OF THE INVENTION

[003] Dust can be collected on surfaces of different kinds and can adversely affect operation of devices associated with the dust covered surfaces. One example of a surface that can be negatively affected by dust collection is a surface of a photovoltaic

("PV") panel (also referred to as a solar panel).

[004] PV panels are most efficiently utilized in sunny areas.

[005] Manny sunny areas globally suffer mostly from dust. Dust that is collected on the (usually glass), surface of PV panels can reduce the irradiation that hit the silicon layer (of the PV panel) by more than 20%.

[006] Most sunny places are located between the Tropic of Cancer and the Tropic of Capricorn where trackers and roof top net-metering configurations are mostly popular.

[007] In a photovoltaic (PV) array, a plurality of solar panels are mount together adjacent to each and may be mounted on big and long tables.

[008] Single Axes PV trackers and roof top tables are usually small in width and length. For example, a fixed tilt solar table usually includes between 4-7 row of solar panels by 100-150 panels in series (total of 400-1000 panels per table) while in trackers and in roof tops installations the table can be as small as 1 row by 40 panels (40 panel per table).

[009] Still those small tables suffer a lot from dust coverage, which impact the effective radiation (photon) reaching the panel.

[0010] Areas (such as deserts) with high irradiation usually suffer from dust and their solar panels usually require more frequent cleaning procedures which manually are very costly. [0011] Robotic cleaning devices must be used. Nevertheless - using a single robot per a solar panel that includes only 40 panels table (each table) instead of 1000 panels table the economics of the cost benefit is different and can kill the investor interests.

[0012] Another factor that influences the PV eco-system is that the system cost decreases as a result of the tariff reduction for KWh (from around $0.4/KWh in 2009 to less than $0.07/KWh in 2016).

[0013] This new eco-system favors cleaning devices which can operate autonomously.

[0014] Preferably a cleaning system should consume fewer materials and consume less energy while still effectively cleaning.

[0015] Some examples of the cleaning device according to the present disclosure can support dry, waterless environment friendly operation, which can be beneficial in desert and dry areas with lack of portable water.

[0016] Dust can cause a reduction of up to 20% in yield. PV fields in desert climate also suffer from lack of water and access to water pipe.

[0017] There is thus a need for frequent cleaning that makes sense in the new world where the value gain from the cleaning is lower (due to tariff) and the size of the table can be in an order of magnitude smaller.

[0018] Some places suffer from dew during night or evening time in one or 2 seasons a year. Cleaning with a dry method, when dew occurs, turns the dust into mud and eliminates the ability to use dry apparatus for cleaning.

[0019] In such case a fast cleaning must be supported so that cleaning can be completed during afternoon in a fast way.

SUMMARY OF THE INVENTION

[0020] According to an aspect of the presently disclosed subject matter there is provided a surface cleaning device. The surface cleaning device may clean surfaces of solar panels and/or other surfaces using dry cleaning methods.

[0021] Optionally, the surface cleaning device can include at least a first and a second dust carrying members a motor and a motion delay assembly.

[0022] The at least first second dust carrying members can be coupled to the motor and the motor can be configured to cyclically move the first dust carrying member and the second dust carrying member over the surface. [0023] The motor may be mechanically coupled (directly or indirectly) to the first and second dust carrier members. The movement of the motors may directly or indirectly cause the first and second dust carrier members to move. Non-limiting example for indirectly mechanically coupling may include having one or more elements such as a gear, a bearing, a rotor, a shaft, cogwheel, axis of rotation, or any motion transmission mechanism, mechanically coupled between the motor and the first and second dust carrier members.

[0024] The first and second dust carrying members can be mechanically coupled to the motor such that when the motor is activated the motion of the first and second dust carrying members is intended to collect and/or push dust primarily in a first direction.

[0025] The motion delay assembly can be configured to momentarily delay a motion of the first dust carrying member approximately at a point where the first dust carrying member lifts above the surface, and the second dust carrying member is at point where it is configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface, while air passage is in the direction of the first dust carrying member is less impeded.

[0026] Optionally, at the time when the motion delay assembly affects the motion of the first dust carrying member, the motion of the second dust carrying member can resume unaffected or not significantly affected.

[0027] Optionally, the motion delay assembly can be configured to cause the air in between the first and the second dust carrying members to be compressed.

[0028] Optionally, the at least the second dust carrying member can have a low permeability to air.

[0029] Optionally, at least the second dust carrying member can be a wiper.

[0030] Optionally, the motion delay assembly can be a physical element that is configured to momentarily delay the motion of the first dust carrying member, while not affecting or not significantly affect the motion of the second dust carrying member.

[0031] Optionally, the motion of the first dust carrying member can be

momentarily delayed when the first dust carrying member comes into contact with the motion delay assembly. [0032] Optionally, the motion delay assembly can be positioned such that the first dust carrying member comes into contact with the motion delay assembly when the first dust carrying member is lifted above the surface.

[0033] Optionally, the motion delay assembly can be positioned such that when the first dust carrying member comes into contact with the motion delay assembly, the second dust carrying member is at point where it is configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface.

[0034] Optionally, the motion delay assembly, the first dust carrying member and the second dust carrying member can be positioned relative to one another such that, the first dust carrying member comes into contact with the motion delay assembly when the first dust carrying member is lifted above the surface and the second dust carrying member is at point where it is configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface.

[0035] Optionally, airflow resulting from increased air pressure can push at least some dust ahead of the second dust carrying member in the first direction further along the surface.

[0036] According to a further aspect of the presently disclosed subject matter there is provided a method of cleaning a surface. The method of cleaning a surface according to examples of the presently disclosed subject matter can include:

moving, using a motor, a first dust carrying member and a second dust carrying member over the surface, where the first and second dust carrying members are mechanically coupled to a motor such that when the motor is activated the motion of the first and second dust carrying members is intended to collect and/or push dust primarily in a first direction; and momentarily delaying a motion of the first dust carrying member approximately at a point where the first dust carrying member lifts above the surface, and the second dust carrying member is at point where it is configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface, while air passage is in the direction of the first dust carrying member is less impeded. [0037] In another aspect of the present disclosed subject matter, a surface cleaning device can include at least one dust carrying member, a motor, and a shaking member.

[0038] The shaking member may be a motion delay element. Alternatively - the shaking member may differ from the motion delay element.

[0039] The motor can be configured to cyclically move the at least one dust carrying member, such the when the motor is activated, the dust carrying member moves generally in a first direction and then turns and moves in generally a second direction that is opposite to the first direction. The shaking member can be positioned at a point along the path of the dust carrying member, such that when the motor is activated and the at least one dust carrying member is in motion, the at least one dust carrying member comes in contact with the shaking member thereby shaking dust off the at least one dust carrying member and preventing at least a portion of the dust carried by the at least one dust carrying member from being carried on in the second direction.

[0040] Optionally the device can include at least a first and a second dust carrying members. The motor can be configured to cyclically move the first and second dust carrying members over the surface, where the first dust carrying member leads the second dust carrying member, and wherein the motion of the first and second dust carrying members is intended to collect or push dust primarily in the first direction.

[0041] Optionally, the at least one dust carrying member can be flexible and the shaking member can be configured to cause a flicking motion of the dust carrying member.

[0042] Optionally, the shaking member can be located in front of the motor generally in a first direction, at a height that is up to 30 degrees above a plane parallel to the surface and passing approximately through a s center of a pivot of the motor and.

[0043] Yet a further aspect of the presently disclosed subject matter, a method cleaning a surface can include: cyclically moving at least one dust carrying member, such the when the dust carrying member moves generally in a first direction and then turns and moves in generally a second direction that is opposite to the first direction; and when the at least one dust carrying member is in motion, shaking dust off the dust carrying member by bringing the dust carrying member in contact with a dust shaking member that is positioned at a point along a path of the dust carrying member, thereby preventing at least a portion of the dust carried by the at least one dust carrying member from being carried on in the second direction.

[0044] Optionally, the device provides a low cost robotic system to clean surface (such PV panels) based on dry wiping and wind blowing apparatus which fits the new eco-system that require light, simple, low maintenance still effective apparatus. It would be appreciated that the term "robot" or "robotic" is used here by way of example, and is not intended to limit the scope of the invention.

[0045] In examples of the presently disclosed subject matter a surface cleaning device can be based on a dual diagonal crisscross movement (Or perpendicular in some cases) on the surface of the panels' table, with rotating wipers and shaking pipe on each side of the rotating wipers' pipe which generate a self-cleaning mechanism for the wipers and a powerful blower that push the dust down to earth.

[0046] The wipers rotation can be in a direction that is against the movement direction to wipe the dust forward, after pushing the dust forward some of the dust particles grab in the wipers. The wiper may impact the shaking pipe to shakeout the dust. When one wiper hits the pipe, it can flick around the pipe, the trailing wiper behind the wiper that hit the pipe can continue its rotation movement. The air pocket between those 2 wipers shrinks, compressing the air in front of the trailing wiper and the air blows forward in the cleaning direction. This provide 4 cleaning elements in one circle movement - dust pushing, dust blowing forward, dust grabbing and self- cleaning for the next cycle. And then, due to centrifuge power, the wiper setback in the original arrangement around the wiper pipe for the next round.

[0047] When the first wiper hits the shaking pipe, it may momentarily stop its rotation or at least significantly reduce its rotation speed, while the trailing wiper pipe resumes its rotation substantially uninterrupted or affected. The wiper behind continue its rotation and the air pocket between those 2 wipers shrinks. The air locked between the 2 wipers, has only one path to get out from the shrinking air pocket- forward. Backward is locked by the wiper behind that in contact with the surface, and is locked in the up direction by the wiper that looped on the shaking pipe. Without the shaking pipe, the air was pushed toward the rotating path, and only fraction of the air move in the cleaning direction. Using the shaking pipe not only clean the wiper, for the next cycle, but provide a powerful blower that throw the dust forward. [0048] In experiments without using a dust shaking pipe, the dust was pushed 0-3 cm away from the wipers, by using the shaking pipe 95% of the particles (includes the heavy ones) was thrown forward over 30 cm. These figures are merely an example, and are non-limiting.

[0049] Pushing the particles mostly by air blow can assist in reducing scratches on the surface of the Panels front glass and the anti-reflective coating.

[0050] While moving along the table the diagonal shape of the rotating wipers together with air blowing and earth gravitation remove many and in some cases substantially all of the dust particles away from table in a short path along the panels.

[0051] Some implementation of a dust cleaning device according to examples of the presently disclosed subject matter can be designed to be light (less than 10kg) and balanced in weight (one engine on each wagon) to allow to move the surface cleaning device on the frame of the panels without the need for additional framing for the surface cleaning device and for allowing drones and/or other transporting means such as a robotic arm to be able to carry them from table to the next table by that reducing the amount of surface cleaning devices s require in the field. Reduce the maintenance and potential failures.

[0052] Optionally, each wiper in each round will physically clean 3-6 cm of surface, the rotating speed will 280 rounds per minute. This will allow the robot to clean up to more than 10 meters in one minute, this is more than 4 times the speed other system capable (such in prior art US871432 B2). It would be appreciated that these figures are not limiting.

[0053] Optionally, moving the robot along the table can be done by pushing the upper wagon by the lower wagon. This pushing apparatus with the stoppers at the edges of the panels' table allow to use 1 engine to move the robot to both sides and save the need of multiple engines.

[0054] When developing a dry-cleaning method another requirement should be a removal path of dust particles along the table should be considered. In an example of the cleaning device according to the present disclosure a short dust removal path is supported and the dust particle can be pushed to a significant extent (a majority of the dust at least in certain cases) by air and less by wiping of the particles by and under the wipers. Dust particles can scratch the glass and the anti-reflective coating on top of the glass. Carrying dust particles by wiping movement can scratch the panels' glass and reduce transparency of the glass. Diminished transparency can reduce the effectiveness of the PV panels since the amount of radiation reaching the silicon layer is reduced.

[0055] It is an object of the present invention to provide apparatus and a method of at least partially removing dust problems off surfaces.

[0056] It is an additional object of the present invention to provide simple and effective system with few engines, materials, and movement to do the work.

[0057] It is additional object to provide a light dust cleaning device to allow the system to run on the panel frames or one light small rail and save the necessity for special rails for holding the system, rails for 20-70kg device can cost alone up to 50- 80% of the system cost.

[0058] It is additional object to allow the wiper a self-cleaning capability so that it can run long way (along the table) while still effectively cleaning the surface. Wipers collect dust during cleaning. The more dust the wipers contain the less effective they are in cleaning new surface, more over in a rotating apparatus when the wipers hit the surface of the panel containing dust they may spray back the dust onto the table (where it was just cleaned).

[0059] It is additional object for the cleaning apparatus to maximize the usage of air blowing and limit the wiping effect (especially of the big dust particles), in order to reduce scratches and impact to the glass layer.

[0060] It is additional object to clean the table in a fast way to minimize the shadowing impact on the table in cases where the cleaning procedure needs to be carried out during the day time and not at night.

[0061] It is an object of some examples of the present disclosure to provide device as light as 8kg to allow drones to move it from one table to another and using the same device for multiple tables.

[0062] It is additional object to design the device with low profile. During the day time, the device can be stowed adjacent to the table (on extension rails outside the table). High profile can generate shadow during day time waiting.

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

[0064] FIG. 1 illustrates an example of at least a portion of a surface cleaning device when moving from a right side of a surface to a left side of the surface in diagonal crisscross way;

[0065] FIG. 2 illustrates an example of at least a portion of a surface cleaning device when the cleaning device hits an end of table stopper positioned at the end of the table;

[0066] FIG. 3 illustrates an example of at least a portion of a surface cleaning device at an end of a turning movement, which change the diagonal direction, this is also the starting position of the surface cleaning device while moving toward the right side;

[0067] FIG. 4 illustrates an example of at least a portion of a surface cleaning device when the surface cleaning device is normal to a longitudinal axis of the surface;

[0068] FIG. 5 illustrates an example of at least a portion of a surface cleaning device at two different points of time;

[0069] FIGs. 6A-6B illustrate an example of at least a portion of a surface cleaning device at two different points of time during a same cleaning cycle;

[0070] FIG. 7 illustrates an example of at least a portion of a surface cleaning device that is moved between surfaces by a drone;

[0071] FIG. 8 illustrates an example of at least a portion of a surface cleaning device that is moved between surfaces by a robotic arm;

[0072] FIG. 9 illustrates an example of at least a portion of a surface cleaning device;

[0073] FIG. 10 illustrates an example of at least a portion of a surface cleaning device;

[0074] FIG. 11 illustrates an example of at least a portion of a surface cleaning device;

[0075] FIG. 12 illustrates an examples of interfacing elements;

[0076] FIG. 13 illustrates an example of at least a portion of a surface cleaning device;

[0077] FIG. 14 illustrates an example of at least a portion of a surface cleaning device; [0078] FIG. 15 illustrates an example of at least a portion of a surface cleaning device;

[0079] FIG. 16 illustrates an example of at least a portion of a surface cleaning device;

[0080] FIG. 17 illustrates an example of at least a portion of a surface cleaning device;

[0081] FIG. 18 illustrates an example of a method;

[0082] FIG. 19 illustrates an example of at least a portion of a surface cleaning device;

[0083] FIG. 20 illustrates an example of at least a portion of a surface cleaning device;

[0084] FIG. 21 illustrates an example of a table and at least a portion of a surface cleaning device; and

[0085] FIG. 18 illustrates an example of a method. DETAILED DESCRIPTION OF THE DRAWINGS

[0086] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

[0087] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings.

[0088] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. [0089] Because the illustrated embodiments of the present invention may for the most part, be implemented using electronic components and circuits known to those skilled in the art, details will not be explained in any greater extent than that considered necessary as illustrated above, for the understanding and appreciation of the underlying concepts of the present invention and in order not to obfuscate or distract from the teachings of the present invention.

[0090] Any reference in the specification to a method should be applied mutatis mutandis to a system or device, unit, mechanism, circuit, or apparatus capable of executing the method.

[0091] Any reference in the specification to a system, device, unit, mechanism, circuit, or apparatus, should be applied mutatis mutandis to a method that may be executed by the system, device, unit, mechanism, circuit, or apparatus.

[0092] The terms system, device, unit, mechanism, circuit, and apparatus are used in an interchangeable manner.

[0093] The terms rod, pipe and axis are used in an interchangeable manner.

[0094] Two directions are generally the same (or belong to the same general direction) when they are equal to each other or do not deviate from each other by more than ninety degrees.

[0095] The term "substantially" - unless stated otherwise may refer to a deviation of few percent (for example- deviation of less than 10% or less than 20 percent).

[0096] The terms "cleaning elements", wipers and "dust carrying members" are used in an interchangeable manner. A dust carrying member is a physical element that is capable of moving dust when contacting the dust during movement (and/or when static). The dust carrying member may absorb or aggregate dust or may not aggregate or absorb dust. The dust carrying member may be made of one or more materials such as but not limited to foam materials (especially soft foam materials), such whisks, soft sponges, soft brushes and hair brushes, the wiper may/or may not include microfibers (for example - microfiber of 150-300 gram per square meter), the wipers may be made of nylon (especially soft nylon), Polypropylene, Polybutylene Terephthalate, leather, and the like.

[0097] Any combination of any system, device, unit, mechanism, circuit, module or component listed in any of the figures, any part of the specification and/or any claims may be provided. Especially any combination of any claimed feature may be provided. Any combination of any method may be provided. For example there may be provided a method that may include steps 310, 320 and 520.

[0098] Any of the surface cleaning device referred to in the specification and/or drawings may perform dry cleaning - without using any fluid to clean the dust or substantially without using fluid to clean the dust. Substantially in this sense means that most of the cleaning process (for example- more than 80% or 90%) is performs by dry cleaning techniques.

[0099] The surface cleaning device can employ a single pipe of rotating wipers which may be moved in relation to the surface by a movement mechanism that may include two wagons that drive along the table with or without special rails (Optional -driving directly on the panels).

[00100] The surface cleaning device can simplify the process of dry cleaning apparatus to the minimum component, which allows the surface cleaning device to fit the new eco-system of low income and low benefit generated from a clean panels and smaller size of panels' table on roof tops and on single axes tracker.

[00101] There may be provided a surface cleaning device for cleaning a surface of a solar panel, wherein the surface cleaning device may include a first dust carrying member; a second dust carrying member; a motor; and a motion delay assembly; wherein the first dust carrying member and the second dust carrying member may be coupled to the motor; wherein the motor may be configured to cyclically move the first dust carrying member and the second dust carrying member along a path; wherein the motion delay assembly may be configured to cyclically introduce a momentarily delay in a progress of the first dust carrying member along the path, while the second dust carrying member contacts the surface, thereby reducing a gap between the first dust carrying member and the second dust carrying member and induce air to exit the gap and progress along the surface and remove dust that precedes the second dust carrying member.

[00102] The second dust carrying member, when contacting the surface, may be configured to at least partially prevent an exit of the air from the gap towards dust that resides on the surface and follows the second dust carrying member.

[00103] The motion delay assembly may be configured to induce the air to exit the gap at a first direction; wherein the second dust carrying member contacts the surface while progressing along the first direction. [00104] The during a single cycle the first dust carrying member may be configured to contact the surface at a first point in time and wherein the motion delay assembly may be configured to introduce the momentarily delay at a second point of time that follows the first point of time.

[00105] The momentary delay may be of a first duration; wherein the first duration exceeds a duration of a delay imposed on a progress of the second dust carrying member due to a contact between the surface and the second dust carrying member.

[00106] The motion delay assembly may be configured to cyclically introduce the momentarily delay when an angle between the first dust carrying member and the second dust carrying member does not exceed one hundred and twenty-five degrees.

[00107] The motion delay assembly may be configured to cyclically introduce the momentarily delay when the first dust lifts from the surface.

[00108] The motion delay assembly may be configured to cyclically introduce the momentarily delay in the progress of the first dust carrying member without delaying a progress of the second dust carrying member along the path.

[00109] The motion delay assembly may be configured to cyclically introduce the momentarily delay in the progress of the first dust carrying member without substantially delaying a progress of the second dust carrying member along the path.

[00110] The motion delay assembly may be configured to remove dust from the first dust carrying member while introducing the momentarily delay.

[00111] The motion delay assembly may be configured to remove dust from the first dust carrying member while introducing the momentarily delay.

[00112] The dust carrying member may be configured to remain static in relation to the first dust carrying member while introducing the momentarily delay.

[00113] The dust carrying member may be configured to move in relation to the first dust carrying member while introducing the momentarily delay.

[00114] The motion delay assembly may be configured to cyclically introduce a momentarily delay in a progress of the second dust carrying member along the path, while the first dust carrying member contacts the surface, thereby reducing the gap between the first dust carrying member and the second dust carrying member and inducing air to exit the gap and progress along the surface and remove dust that precedes the first dust carrying member. [00115] The second dust carrying member may be configured to aggregate dust when contacting the surface.

[00116] The second dust carrying member may be configured not to aggregate dust when contacting the surface.

[00117] The surface cleaning device may be configured to move the motion delay assembly between a first position in which the motion delay assembly may be within a reach of the first dust carrying member and between a second position in which the motion delay assembly may be outside the reach of the first dust carrying member.

[00118] The surface cleaning device may be configured to position the motion delay assembly at a first position when the surface cleaning device propagates towards one end of the surface and may be configured to position the motion delay assembly at a second position when the surface cleaning device propagates towards another end of the surface; wherein when positioned in the first position the motion delay assembly may be within a reach of the first dust carrying member and when positioned at the second position the motion delay assembly may be outside the reach of the first dust carrying member.

[00119] The motor may be configured to cyclically move the first dust carrying member and the second dust carrying member along the path by rotating the first dust carrying member and the second dust carrying member about an axis of rotation.

[00120] The distance between the motion delay assembly and the axis of rotation may be smaller than a distance between the axis of rotation and the surface when the second dust carrying member contacts.

[00121] The distance between the motion delay assembly and the axis may be smaller by at least ten percent than the distance between the axis of rotation and the surface when the second dust carrying member contact.

[00122] The surface cleaning device may include a movement mechanism for moving the surface cleaning device in relation to the surface while maintaining a substantially constant angle between a longitudinal axis of the surface and the axis of rotation.

[00123] The substantially constant angle may differ from ninety degrees. [00124] The surface cleaning device may include a movement mechanism that may be configured to (a) move the surface cleaning device towards an end of the surface while maintaining a first tilt angle between the axis of rotation and a longitudinal axis of the surface, and (b) move the surface cleaning device towards another end of the surface while maintaining a second tilt angle between the axis of rotation and a longitudinal axis of the surface; wherein the first tilt angle may differ from the second tile angle.

[00125] The first tile angle and the second tilt angle differ from ninety degrees.

[00126] The absolute value of an angular difference between a normal to the longitudinal axis and the first tilt angle may equal an absolute value of an angular difference between the normal to the longitudinal axis and the second tilt angle equal.

[00127] The motion delay assembly may include a pipe that may be parallel to the axis of rotation.

[00128] The motion delay assembly may include a pipe that may be oriented in relation to the axis of rotation.

[00129] The motion delay assembly may include a first motion delay element that may be positioned at a first side of the motion delay assembly; a second motion delay element that may be positioned at a second side of the motion delay assembly; and a manipulator that may be configured to selectively position at least one of the first and second motion delay elements within the path of the first dust carrying member.

[00130] The manipulator may be configured to selectively position the at least one of the first and second motion delay elements within the path of the first dust carrying member by rotating a connecting element that may be connected to the first and second motion delay elements.

[00131] The motion delay assembly may include a first motion delay element that may be positioned at a first side of the motion delay assembly, a second motion delay element that may be positioned at a second side of the motion delay assembly and a manipulator that may be configured to position the first motion delay element within the path of the first dust carrying member when the surface cleaning device propagates towards an end of the surface and to position the second motion delay element within the path of the first dust carrying member when the surface cleaning device propagates towards another end of the surface. [00132] The manipulator may be configured to position the second motion delay element outside the path of the first dust carrying member when the surface cleaning device propagates towards the end of the surface and to position the first motion delay element outside the path of the first dust carrying member when the surface cleaning device propagates towards the other end of the surface.

[00133] The at least a portion of the first dust carrying member may be configured to partially wound around a motion delay element of the motion delay assembly when the motion delay assembly introduces the momentarily delay in the progress of the first dust carrying member.

[00134] The at least portion of the first dust carrying member may be configured to unwound after partially wounding around the motion delay element.

[00135] The surface cleaning device may include a group of dust carrying members, wherein the dust carrying members may include the first and second dust carrying members and at least one additional dust carrying member.

[00136] The motor may be configured to cyclically move each dust carrying member of the group along the path; wherein the wherein the motion delay assembly may be configured to cyclically introduce the momentarily delay in a progress of the each dust carrying member of the group along the path, while a following dust carrier member of the group contacts the surface, thereby reducing a gap between the dust carrying member and the following dust carrying member and inducing air to exit the gap and progress along the surface and remove dust that precedes the dust carrying member.

[00137] The group may include at least four dust carrying member.

[00138] The one dust carrying member of the group may differ from at least one other dust carrying member of the group.

[00139] The one dust carrying member of the group may equal at least one other dust carrying member of the group.

[00140] The motor may be configured to move the dust carrying members of the group along a circular path.

[00141] The motor may be configured to move the dust carrying members of the group along an elliptical and non-circular path.

[00142] The motor may be configured to move the dust carrying members of the group along a polygon shaped path. [00143] The surface cleaning device may include at least one environment sensor that may be configured to sense at least one environmental condition.

[00144] The at least one environmental sensor may be a humidity sensor.

[00145] The at least one environmental sensor may be a rain sensor.

[00146] The at least one environmental sensor may be a wind sensor.

[00147] The at least one environmental sensor may be a sun radiation sensor.

[00148] The surface cleaning device may include a controller that may be configured to control the operation of the surface cleaning device based on one or more environmental conditions of the at least one environmental condition.

[00149] The controller may be configured to control the operation of the surface cleaning device by setting at least one out of (a) a speed of movement of the surface cleaning device, (b) a speed of movement of the first and second dust carrying members.

[00150] The at least one environmental sensor may be a humidity sensor and wherein the controller may be configured to prevent an execution of cleaning cycles when a humidity sensed by the humidity sensor exceeds a predefined humidity threshold.

[00151] The at least one environmental sensor may be a rain sensor and wherein the controller may be configured to prevent an execution of cleaning cycles when rain may be sensed by the rain sensor.

[00152] The at least one environmental sensor may be a wind sensor and wherein the controller may be configured to prevent an execution of cleaning cycles when wind of a predefined speed may be sensed by the wind sensor.

[00153] The at least one environmental sensor may be a wind sensor and wherein the controller may be configured to prevent an execution of cleaning cycles when wind of a predefined direction may be sensed by the wind sensor.

[00154] The at least one environmental sensor may be a wind sensor and wherein the controller may be configured to prevent an execution of cleaning cycle that involve blowing the air from the gap at a direction that may be opposite to a direction of the wind.

[00155] The surface cleaning device may include at least one sensor that may be configured to sense a state parameter of the surface cleaning device. [00156] The surface cleaning device may include at least one solar panel for generating electrical energy for powering the surface cleaning device.

[00157] The surface cleaning device may include at least one battery for providing electrical energy for powering the surface cleaning device.

[00158] The surface cleaning device may consist essentially of the motor, the motion delay assembly and a group of dust carrying members, wherein the group of the dust carrying members may include the first and second dust carrying members.

[00159] The surface cleaning device may consist essentially of the motor, the motion delay assembly, a group of dust carrying members and a movement mechanism for moving the surface cleaning device in relation to the surface; wherein the group of the dust carrying members may include the first and second dust carrying members.

[00160] The surface cleaning device wherein the surface cleaning device cleans the surface without washing the surface

[00161] The motion delay assembly may include a motion delay element that may be configured to introduce the momentary delay.

[00162] The friction coefficient of the motion delay element exceeds a friction coefficient of the surface.

[00163] The surface cleaning device wherein the motor may be configured to cyclically move, at a constant speed, the first dust carrying member and the second dust carrying member along the path.

[00164] The surface cleaning device wherein the motor may be configured to cyclically move, at a variable speed, the first dust carrying member and the second dust carrying member along the path.

[00165] The surface cleaning device may include a movement mechanism for moving the surface cleaning device at a constant speed in relation to the surface.

[00166] The surface cleaning device may include a movement mechanism for moving the surface cleaning device at a variable speed in relation to the surface.

[00167] There may be provided a surface cleaning device for cleaning a surface of a solar panel, wherein the surface cleaning that may include a first dust carrying member; a second dust carrying member; a motor; and a shaking member; wherein the first dust carrying member and the second dust carrying member may be coupled to the motor; wherein the motor may be configured to cyclically move the first dust carrying member and the second dust carrying member along a path; wherein the first dust carrying member may be configured to (a) contact the surface while progressing at a first direction, and following the contact with the surface (b), collide with the shaking member thereby removing dust from the first dust carrying member; and wherein the surface cleaning device may be configured to at least partially block the dust removed from the first dust carrying member to progress at a direction that may be opposite to the first direction.

[00168] There may be provided a surface cleaning device for dry cleaning of a surface of a solar panel, wherein the surface cleaning that may include a group of cleaning elements; a motorized unit that may be configured to perform multiple cleaning cycles; wherein during each cleaning cycle the motorized unit may be configured to move cleaning elements of the group in relation to the surface; a motion delay assembly that may be configured , during each cleaning cycle to introduce a momentarily delay in a progress of a cleaning element carrying member along the path, while a following cleaning element contacts the surface, thereby reducing a gap between the cleaning element and the following cleaning element and inducing air to exit the gap and progress along the surface and removes dust that precedes the cleaning element.

[00169] Each cleaning element may be a dust carrying member.

[00170] Each cleaning element may be flexible.

[00171] There may be provided a surface cleaning device, that may include first and second dust carrying members; a motor configured to cyclically move the first dust carrying member and the second dust carrying member over the surface, where the first and second dust carrying members may be mechanically coupled to the motor such that when the motor may be activated the motion of the first and second dust carrying members perform at least one out of collect dust and pushing dust primarily in a first direction; and a motion delay assembly configured to momentarily delay a motion of the first dust carrying member approximately at a point where the first dust carrying member lifts above the surface, and the second dust carrying member may be at point where it at least partially blocks air passage in a second direction generally opposite to its current direction of movement relative to the surface, while air passage in a general direction of the first dust carrying member may be less impeded.

[00172] The at a time when the motion delay assembly affects the motion of the first dust carrying member, the motion of the second dust carrying member resumes unaffected or not significantly affected.

[00173] The motion delay assembly may be configured to cause the air between the first and the second dust carrying members to be compressed.

[00174] The at least the second dust carrying member has a low permeability to air.

[00175] The at least the second dust carrying member may be a wiper.

[00176] The motion delay assembly may be a physical element that may be configured to momentarily delay the motion of the first dust carrying member, while not affecting or not significantly affecting the motion of the second dust carrying member.

[00177] The motion delay assembly may be configured to momentary delay the motion of the first dust carrying member when the first dust carrying member comes into contact with the motion delay assembly.

[00178] The motion delay assembly may be positioned such that the first dust carrying member comes into contact with the motion delay assembly when the first dust carrying member may be lifted above the surface.

[00179] The motion delay assembly may be positioned such that when the first dust carrying member comes into contact with the motion delay assembly, the second dust carrying member may be at point where it may be configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface.

[00180] The motion delay assembly, the first dust carrying member and the second dust carrying member may be positioned relative to one another such that, the first dust carrying member comes into contact with the motion delay assembly when the first dust carrying member may be lifted above the surface and the second dust carrying member may be at point where it may be configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface. [00181] The airflow resulting from increased air pressure pushes at least some dust ahead of the second dust carrying member in the first direction along the surface.

[00182] There may be provided a method of cleaning a surface, the method may include moving, using a motor, a first dust carrying member and a second dust carrying member over the surface, where the first and second dust carrying members may be mechanically coupled to a motor such that when the motor may be activated the motion of the first and second dust carrying members may be configured to perform at least one out of collecting dust and pushing dust primarily in a first direction; momentarily delaying a motion of the first dust carrying member approximately at a point where the first dust carrying member lifts above the surface, and the second dust carrying member may be at point where it may be configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface, while air passage may be in the direction of the first dust carrying member may be less impeded.

[00183] There may be provided a surface cleaning device that may include at least one dust carrying member; a motor configured to cyclically move the at least one dust carrying member, such the when the motor may be activated, the dust carrying member moves generally in a first direction and then turns and moves in generally a second direction that may be opposite to the first direction; a shaking member that may be positioned at a point along the path of the dust carrying member, such that when the motor may be activated and the at least one dust carrying member may be in motion, the at least one dust carrying member comes in contact with the shaking member thereby shaking dust off the at least one dust carrying member and preventing at least a portion of the dust carried by the at least one dust carrying member from being carried on in the second direction.

[00184] The device may include at least a first and a second dust carrying members, and wherein the motor may be configured to cyclically move the first and second dust carrying members over the surface, where the first dust carrying member leads the second dust carrying member, and wherein the motion of the first and second dust carrying members may be intended to collect or push dust primarily in the first direction. [00185] The at least one dust carrying member may be flexible and the shaking member may be configured to cause a flicking motion of the dust carrying member.

[00186] The shaking member may be located in front of the motor generally in a first direction, at a height that may be up to degrees above a plane parallel to the surface and passing approximately through a s center of a pivot of the motor and.

[00187] There may be provided a method for cleaning a surface, may include cyclically moving at least one dust carrying member, such the when the dust carrying member moves generally in a first direction and then turns and moves in generally a second direction that may be opposite to the first direction; and when the at least one dust carrying member may be in motion, shaking dust off the dust carrying member by bringing the dust carrying member in contact with a dust shaking member that may be positioned at a point along a path of the dust carrying member, thereby preventing at least a portion of the dust carried by the at least one dust carrying member from being carried on in the second direction.

[00188] There may be provided a method for cleaning of a surface of a solar panel, the method may include moving, using a motor, a first dust carrying member and a second dust carrying member over the surface to perform at least one out of collecting dust and pushing dust primarily in a first direction; momentarily delaying a motion of the first dust carrying member approximately at a point where the first dust carrying member lifts above the surface, and the second dust carrying member may be at point where it may be configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface, while air passage may be in the direction of the first dust carrying member may be less impeded.

[00189] The method may include repeating the moving and the momentarily delaying multiple times.

[00190] The method may include moving the surface cleaning device in relation the surface.

[00191] The method wherein the cleaning may be a dry cleaning.

[00192]

[00193] [00194]

[00195]

[00196] The surface cleaning device 100 of figure 1 may include: (a) a movement mechanism that may include upper wagon 3, lower wagon 9 that have with wheels, (b) a pivot pole 5 (also referred to as axis of rotation) that may be mechanically coupled to the wheels by bearing 2, (c) an engine 13 for moving the lower wagon, (d) a motor 1 for moving the wipers - for example by rotating the pivot pipe, (d) four wipers 4 (may be four rows of wipers) that are mechanically coupled to pivot pole 5, (e) battery 14, and (f) left shaking pipe 6 and right shaking pipe 6' that are positioned on different sides of the pivot pole 5.

[00197] The surface cleaning device 100 is lightweight - and represents a reduction of weight in one order of magnitude from tens of kg (25-90kg) to less than 8 kg. These weights are merely a non-limiting example of the weight of the surface cleaning device.

[00198] Decreasing the weight of the surface cleaning device allow to reduce the cost of components (such as steel) of the surface cleaning device and allows to reduce any supporting mechanism (such as rails 11 and 11 ') and consume less energy - thus required a lighter energy source.

[00199] Optionally, the energy unit for operation of the surface cleaning device can be based on charging a battery through the day by solar panel and activating the engines on energy provided by the battery when cleaning procedure is required.

[00200] The low weight surface cleaning device may be easily carried from one table to the other by drone or light robotic arm (see figures 7 and 8).

[00201] The surface cleaning device may move while being at any angle in relation to the longitudinal axis of the panel. The angle may change over time, may remain the same, may change depending on the tilt angle (in relation to the horizon) of the panel, may change in relation to the direction of movement of the surface cleaning device, may change based on environmental conditions, and the like.

[00202] Figures 1-3 illustrates the surface cleaning device 100 as moving in a tilted angle (that is not normal to the longitudinal axis of the panel) when progressing towards the left end of the panel and then moving at another tilted angle when progressing towards the right end of the panel. Figures 1-4 illustrates two table (gray blocks) and a gap between the table - that is bridges by rails 11 and 11 ' .

[00203] The movement is referred to as a crisscross diagonal crisscross movement.

[00204] In figures 1-3 the upper end of the surface cleaning device precedes the lower end of the surface cleaning device - thereby allowing removed dust to be moved away from the panel. When tilted at such tilt angle dust should not fall back on the surface cleaning device.

[00205] Accordingly- the dust removal may benefit from the dust removal operations executed by the surface cleaning device and also benefit from gravity.

[00206] In figure 1 the surface cleaning device moves toward the left end of the panel (arrow 12 represents this movement) and at least most of the dust that is removed by the surface cleaning device is directed in a general direction that is normal to the tilt angle - and does not come back towards the surface cleaning device.

[00207] Assuming that the table is tilted (within a plane that is normal to the plane of figure 1) the surface cleaning device removes dust that will fall downwards and not be carried by the surface cleaning device during the entire progress from one end of the table to another end of the table.

[00208] Optionally the tilt angle may range between 20-40 degrees from a latitudinal axis of the table. For example, when the tile angle is thirty degrees in relation to the latitudinal axis of the table and the width of the table is 2 meters - dust particles will be carried over less than 2.5 meters (in average). If considering that the tilt of the table is above zero than the wind blowing and gravitation will carry the dust particle along a much shorter way. Other parameters and configurations can be used.

[00209] Optionally, the surface cleaning device can improve the air blowing effect, which can help to reduce the scratches impact and reduce the amount of time the surface cleaning device needs to travel for reaching ninety nine percent efficiency of dust removal, due to spraying the dust backward (pick the dust up by the microfiber and sending it backward due to the centrifuge power and hitting the panels surface again with dust particles).

[00210] The diagonal movement of the surface cleaning device may be optimized when the motorized mechanism includes only one engine and is configured to push the surface cleaning device for progressing from one end of the panel to another.

[00211] Referring to figures 1 and 2 - the upper rail 11 and the lower rail 11 ' extend beyond the left end of the table and beyond the right end of the table.

[00212] There is a left pivot 10 that precedes the left end of the table and a right pivot 10' that precedes the right end of the table.

[00213] The upper rail 11 may include three segments - left segment, intermediate segment, and right segment. These segments are virtually partitioned by left pivot 10 and right pivot 10' - left segment is to the left of left pivot 10, intermediate segment is between left and right pivots and the right segment is to the right of right pivot 10'. The left segment may rotate in relation to the intermediate segment using left pivot 10. The right segment may rotate in relation to the intermediate segment using right pivot 10'. The rotations are required during a change direction process during which the surface cleaning device changes the direction of movement (and cleaning) - from left to right or from right to left.

[00214] When the surface cleaning device has to change its movement from a left direction to the right direction the rotation of the left segment enables the change of movement to succeed. The rotation of the left segment is required when the overall length of the surface cleaning device exceeds the distance between the upper and lower rails and thus the distance between the lower segments and the left segment should be changed when changing the direction. The same applies to the right segment.

[00215] The motor of the lower wagon 9 pushes the lower wagon to the left

12. Even after an upper part of left stopper 7 contacts a left shaking pipe 6 and prevents upper wagon 3 to progress to the left.

[00216] The left stopper 7 may act as a pivot- whereas while the motor of lower wagon 9 continues moving to the left (arrow 16) - the left stopper 7 causes the upper wagon 3 and the upper part of the surface cleaning device to progress to the right.

[00217] When the lower wagon reaches a certain position - for example when the lower end of the axis or rotation 5 reaches the left end of the panel - the motor of the lower wagon 9 reverses its rotation direction (or any other mechanical arrangement changes the progress direction of the lower wagon) - and the lower wagon - and the entire surface cleaning device start moving to the right (see arrow 18 of figure 3).

[00218] Arrow 15 illustrates the reverse of direction and arrow 17 points to the left segment of the upper rail - when positioned at an upmost position.

[00219] When the turning movement is completed the left segment of the upper rail returns to its lower position.

[00220] The same procedure occurs near the right end of the table - when changing the movement of the surface cleaning device from right to left.

[00221] The surface cleaning device when cleaning the surface may generate a dust blowing effect.

[00222] Figure 4 illustrates the surface cleaning device 100 as moving in a non-tilted angle (normal to the longitudinal axis of the panel) when progressing towards the left end of the panel.

[00223] Figures 1 -3 and 5 illustrate a left shaking pipe 6 and right shaking pipe

6'.

[00224] When the general cleaning direction is left (and the surface cleaning device cleans the surface while moving to the left) then (a) the left shaking pipe 6 should be "activated" (within the reach or path of the dust carrier members) and the right shaking pipe 6' should be "deactivated" (outside the reach or path of the right shaking pipe 6')·

[00225] When the general cleaning direction is right (and the surface cleaning device cleans the surface while moving to the right) then (a) the right shaking pipe 6 should be "activated" (within the reach or path of the dust carrier members) and the left shaking pipe 6' should be "deactivated" (outside the reach or path of the left shaking pipe 6')·

[00226] This selective activation and deactivation may be facilitated in various manners. For example - the right shaking pipe 6' and the left shaking pipe 6 may be moved in and out of reach of the dust carrying members by a manipulator.

[00227] There may be a separate manipulator for each one of the right shaking pipe 6' and the left shaking pipe 6. The manipulation may involve any kind of movement - rotation, turning, linear and the like. [00228] In figure 5 the manipulator includes a right frame 21 that is connected to the right shaking pipe 6' and a left frame 18 that is connected to the left shaking pipe 6. Pivot rotates these frames 20 (rotation denoted by arrow 24).

[00229] The left part of figure 5 illustrates a state where the frames are rotated to the left - the right shaking pipe 6' is activated and the left shaking pipe 6 is deactivated.

[00230] The right part of figure 5 illustrates a state where the frames are rotated to the right (arrow 25) - the left shaking pipe 6 is activated and the right shaking pipe 6' is deactivated.

[00231] The dust carrying member is arranged to direct dust away from the dust carrying member - and prevent (or at least substantially prevent) the dust that it removed from returning backwards.

[00232] Accordingly - when a segment of the surface was recently cleaned by the dust carrying member - then the dust carrying member will prevent or substantially prevent duct from returning to that segment.

[00233] The dust carrying member may prevent the dust from moving backwards by performing at least one out of dust blowing away from the dust carrying member (especially using air that exits a momentarily compressed gap between the wipers), self-cleaning of the dust carrying members (in front of the dust carrying member), and at least partially blocking the backflow of dust by a wiper that may contact the surface thereby at least partially blocking the back flow of dust.

[00234] Figures 6 A, 6B, 6C and 6C may illustrate different phases is a cleaning cycle.

[00235] In Figure 6A the first wiper and second wiper (marked in dashed lines) are fully stretched. The first wiper hits the surface of the panel and grab the dust 28.

[00236] When the wiper touches the surface 29, he cleans the surface and may grab the dust in his fibers.

[00237] In Figure 6B the wipers continue their rotation and the first wiper moves toward the right shaking pipe 6'.

[00238] The first wiper hits the right shaking pipe 6' thereby removing dust

30 from the first wiper. Moreover, since the right shaking pipe 6' is rounded (compared with the flat surface of the panel 29), the first wiper loops around the right shaking pipe 6', and blocked it from continuing the rotation while the following wiper, continues moving. The right shaking pipe and the left shaking pipe may have any other shape and/or size.

[00239] The first wiper progress is delayed in relation to the progress of the following wiper us appear. This causes a compression (at the general direction of cleaning) of the gap between the first wiper and the following wiper. The compression of the gap may be evaluated when comparing the gap that is illustrated in figure 6B to the gap (compressed gap) that is illustrated in figure 6C. The compression ratio may exceed one, two, three, four, five and the like.

[00240] In figures 6B and 6C the following wiper contacts the surface and provide a seal (or a substantial seal) that prevents (or substantially prevents) the flow of air behind the following wiper

[00241] As in Figure 6C the following wiper touches the surface and seals the air path backward and the gap (air pocket) between the wipers is compressed - resulting in a relatively significant air blow away from the surface cleaning device.

[00242] It should be noted that the first wiper that is wound around the right shaking pipe 6' (or otherwise is contacted by the right shaking pipe) also substantially prevents the air from escaping upwards - and may direct the air that escapes the gap not only forwards but also towards the surface (and the dust that is on the surface).

[00243] This air also directs the dust 30 removed from the first wiper (by the right shaking pipe) forwards- away from the surface cleaning device - while preventing (or substantially preventing) dust to flow backwards.

[00244] In Figure 6D the rotation of the wipers continues. The first wiper escapes the right shaking pipe 6' (it is pushed out from the looped position on the right shaking pipe 6') with very small distance between its position and the wiper behind.

[00245] Due to the centrifuge power, along its circulation, the first wiper is stretched out and the gap between the first wiper and the preceding wiper increases wipers again, thereby allowing the gap to expand and form an air pocket for the next blowing routine.

[00246] The right shaking pipe is positioned at the direction of the movement of the surface cleaning device and increases dramatically the effectiveness of the surface cleaning device as dust that removed from the wiper is blown forwards by a powerful dust blower - without a substantial amount of dust that moves backward. [00247] The principal of the apparatus detail design has many option based on preferred wiper material, type of sand in the specific region, length of the table, but in all cases the apparatus design may or may not be based on few principals that may or may not be implemented.

[00248] Shaking pipe height from the table - it may be positioned at an angle of up to 125 degrees (zero is down from the pivot toward the panels surface) to create the dust cloud low enough not to spray the dust backward. This limitation also allows the wiper another 235 degrees of movement, till it hits the panel again to be stretched out using the centrifuge force. Nevertheless - the angle of deviation (125 degrees) is a non-limiting example and the angle may change from 125 degrees.

[00249] Wiper length - it may be beneficial to have the wiper loop on the shaking pipes and that the resistance (to backward wind) of the wiper when moving along the surface of the panel is much lower than the resistance (amount of force that will free the wiper) of the looped wiper on the shaking pipe. This allows the air pocket between any adjacent wipers to shrink and generate a significant the wind blowing effect.

[00250] Positioning of the following wiper to contact the surface during the looping of the preceding wiper on the shaking pipe. This will provide a backward seal for preventing the air in the gap to flow backwards.

[00251] Stretching out process - the end of the wiper may or may not be heavier for smoothing and hurrying the stretching movement of the wiper along the path maximizing the centrifuge force acting on the wipers while circulating.

[00252] The material of the wiper can be changed but the design should be attached to the flexibility and weight of the material.

[00253] When implementing at least some of the mentioned above requirements the surface cleaning device may be benefit from:

An increase in the wind speed in the direction of the panel (for example - by a factor of four in comparison to rotating wipers without the shaking pipe).

Prevent dust from be directed backwards.

Facilitate a simple and compact system.

[00254] In a proof of concept (as described in the picture below - measurements in cm described in gray color) the surface cleaning device handled 25 grams per square meter dust (represent heavy dust layer generated on extreme sand storm) with wipers that were made of 200 grams per square meter microfiber that were folded into two, and the axis of rotation rotated at a speed of 280 round per minute. This surface cleaning device achieved in one round of cleaning (cleaning while moving to a single direction) a reduction of 99% of dust. In this proof of concept, the wagon speed was 5 meters per minute.

[00255] In this proof of concept, the wipers width (distance from the rotating pipe) were 4.5 cm longer (20cm) than the distance (15.5 cm) between the rotating pipe and the surface of the solar panel.

[00256] Due to the high speed of rotation only the last 2 cm of wiper really touch the glass - is such case the effective wiping surface of each wiper is 5cm of glass. If each second the rotating pipe performs 4.5 rounds, then overall 18 wiping operations (assuming four wipers each round) are executed per second and the wagon moves 10 centimeters per second.

[00257] This proof of concept illustrated a complete clean (over 99% removal of dust) of 25 grams of dust per square meter of surface (represent a moderate storm), in one round.

[00258] Another important device for cost reduction and maintenance reduction is the ability to move the robot between tables.

[00259] Figure 7 describes using a rail and/or a drone and/or a robotic arm for moving the surface cleaning device from one table to the other.

[00260] Any system or device that may carry the surface cleaning device may move the surface cleaning device. The carrying of the surface cleaning device is simplified and is cheaper in comparison to other devices due to the light weight of the surface cleaning device.

[00261] The left side of figure 7 illustrates an array of tables 35 that aligned with adjacent tables 36 and each table and adjacent table are close enough to enable a rail to be connected to different tables of a row and thus the drone and/or robotic arm will move the surface cleaning device between one row to the other.

[00262] The right part of figure 7 illustrates tables that are aligned but are spaced apart from each other and may require a drone or a robotic arm to move the surface cleaning device between different tables.

[00263] Figure 8 illustrates a robotic arm that is move the surface cleaning device between tables of the same row that are also spaced apart from each other and between tables of different rows. A road or wide enough path may be formed between the tables and the robotic arm may move along the road.

[00264] Figure 9 is a front view of a table 101, and surface cleaning device

100 that illustrates a lower wagon 9, pivot pole 5 that is rotated by motor 1, a frame 117 that supports the pivot pole 5, left shaking pipe 6, right shaking pipe 6', pivot 20, engine 13, lower rail 11 ' and wheels 118 of the lower wagon that are positioned at both sides of the lower rail.

[00265] Figure 10 is a side view of surface cleaning device 100 that illustrates a lower wagon 9, pivot pole 5 that is rotated by motor 1, a frame 117 that supports the pivot pole 5, left shaking pipe 6, right shaking pipe 6', pivot 20, engine 13, left frame 18, right frame 21, lower rail 11 ' and wheels 118 of the lower wagon that are positioned at both sides of the lower rail.

[00266] The pivot pole 5 has holders 161 for holding poles 162 that are attached to the wipers 163.

[00267] Figure 11 is a top view that illustrates bearing 2 that allows the pivot pole 5 to rotate in relation to the lower rail (and enables a change of the angle between the surface cleaning device and the surface), motor 1, left and right shaking pipes 6 and 6', and lower wagon 9.

[00268] Figure 12 illustrates various wiper interfaces that are not circular.

Previous figures illustrated a rotating pole that defined a circular path - it forced the wipers (at least the inner ends of the wipers) to follow a circular path. Figure 12 illustrates wiper interfaces that are non-circular.

[00269] Wiper interface 130 is elliptical, wiper interface 140 approximates a rectangle but has round corners and wiper interface 150 is a polygon. The wiper interfaces may be track or any other interfacing element that may be moved (directly or indirectly) by one or more motors.

[00270] Figure 13 illustrates surface cleaning device 100 that is powered by solar panels 61 and 62 that are positioned to the left and the right of the pivot pole 5. The solar panels may be located in any position - and especially outside the reach of the wipers. Alternatively, a solar panel may act as a motion delay element. The solar panels may be positioned above the pivot pole 5.

[00271] Figure 13 also illustrates pivot pole 5, left and right shaking pipes 6 and 6' and two movement mechanism units 71 and 72 for moving the surface cleaning device 100. The movement mechanism units 71 and 72 may be wagons or may differ from wagons.

[00272] The number of solar panels may be one, two or exceed two.

[00273] Figure 14 illustrates surface cleaning device 100 that has a controller

80. The controller 80 may be a hardware controller that may include one or more integrated circuits. The controller 80 may be positioned in any location and may be included in any of the surface cleaning devices 100 of any other figure.

[00274] The surface cleaning device 100 may include one or more sensors such as but not limited to (a) at least one environment sensor that is configured to sense at least one environmental condition, and/or (b) at least one state sensor that is configured to sense a state parameter of the surface cleaning device.

[00275] The at least one environmental sensor may be a humidity sensor. A rain sensor, a temperature sensor, a wind sensor, and a sun radiation sensor.

[00276] The at least one state sensor may sense the functionality of various components of the surface cleaning device 100, the energetic state of the surface cleaning device 100 - especially whether the surface cleaning device 100 has enough power to complete a scheduled cleaning task. The sensor may sense the state of the wipers - especially are they worn and/or torn, are they elastic enough, whether they aggregated too much dust, when these wipers should be replaced, washed, or undergo any treatment. The state sensor may receive feedback from components of the surface cleaning device and/or may check the status without receiving feedback.

[00277] The wind sensor may sense the speed of the wind and/or the direction of the wind. When the speed of the wind is too high the controller 80 may decide not to perform any cleaning operation for safety reason.

[00278] When the wind sensor detects a wind direction the controller may determine not to perform any cleaning operation that attempts to remove dust in a direction that is in the general direction of the wind direction.

[00279] The controller may determine not to perform any cleaning operation that attempts to remove dust at a certain direction when (a) the wind speed is a above a certain threshold (significant wind), and (b) the wind direction is in the general direction of the certain direction.

[00280] Figures 15 and 16 illustrates various sensors 84 and 86. The number of sensors per surface cleaning device 100 may range between zero and at least five. Sensors 84 and 86 may represent any type of sensors - state sensors and/or environmental sensors. Figure 16 also illustrates a communication module 88 for communication with another device 400. The communication module 88 may communicate in any manner- especially wireless short-range communication - that may be less energy consuming than satellite communication and/or cellular communication. The other device 400 may be a sensor that feeds the surface cleaning device with information (such as environmental condition, state of the surface cleaning device), the other device 400 may be a control unit for controlling the surface cleaning device. The other device may be a communication relay. The other device may be a drone and/or a robotic arm, and the surface cleaning device may signal when it finished cleaning a table and should be taken to another table.

[00281] Figure 16 illustrates surface cleaning device 100 without solar panels but with battery - but the surface cleaning device 100 may include both one or more solar panels and one or more batteries.

[00282] Figure 17 illustrates that the left and shaking pipes 6 and 6' may be reciprocated by motors (or any other manipulators) by one or more various manners

(horizontally, vertically, in a linear and non-linear manner) - or otherwise cyclically moved so as to contact the wipers while moving.

[00283] Figure 18 illustrates method 300 for dry cleaning.

[00284] Method 300 may start by steps 310 and 320.

[00285] Step 310 may include moving, using a motor, a first dust carrying member and a second dust carrying member over the surface. The first and second dust carrying members are mechanically coupled to a motor and step 310 includes moving the first and second dust carrying members to perform at least one out of collecting dust and pushing dust primarily in a first direction.

[00286] Step 320 includes momentarily delaying a motion of a first dust carrying member approximately at a point where the first dust carrying member lifts above the surface, and the second dust carrying member is at point where it is configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface, while air passage is in the direction of the first dust carrying member is less impeded.

[00287] The momentarily delay may be introduced even before the second dust carrier contacts the surface, may be introduced even after the dust carrier lifts from the surface, may be introduced during the entire period of contact between the surface and the second dust carrier member and may be introduced only during of a part of the period of contact between the surface and the second dust carrying member.

[00288] Approximately at the point where the first dust carrying member lifts above the surface may be any point before the first dust carrying member reaches its peak, at any point where the angle between the first dust carrier member (especially the base of the first dust carrying member) and a normal to the surface may be between zero and one hundred twenty-five degrees.

[00289] Steps 310 and 320 may be repeated multiple times- during multiple cleaning cycles.

[00290] Step 320 may also include momentarily delaying a motion of the second dust carrying member approximately at a point where the second dust carrying member lifts above the surface, and the first dust carrying member (or any other dust carrying member that follows the second duct carrying member) is at point where it is configured to at least partially block air passage in a second direction generally opposite to its current direction of movement relative to the surface, while air passage is in the direction of the second dust carrying member is less impeded.

[00291] Method 300 may also include step 330 of moving a surface cleaning device in relation the surface.

[00292] Step 330 may be executed in parallel (with a certain overlap or in a staggered manner - even without overlap) to steps 310 and 320.

[00293] The moving may be continuous or non-continuous.

[00294] It should be noted that the wagons are merely a non-limiting example of a movement mechanism units that may move the surface cleaning device.

[00295] The surface cleaning device may move on the panel and not on the rails and/or the surface cleaning device may interface with the panel in any other manner.

[00296] The pivot pipe and/or the shaking pipes are merely non-limiting examples of shaking elements and/or motion delay elements. The shaking elements and/or motion delay elements may differ from pipes, may be smooth or have a rugger exterior, may have a cross section that is not circular, and the like. [00297] It should be noted that although the various figures illustrate left and right movements that the surface cleaning device 100 may move along any pattern and in any direction. For example - the surface cleaning device 100 may move vertically (up and down), perform a polygon shaped pattern and the like. Different patterns may require holding to the surface cleaning device 100 to the solar panels in manners that differ from those illustrated above.

[00298] It should be noted that although the various figures illustrated a surface cleaning device that long enough to cover the entire width of the table - this is not necessarily so. For example - surface cleaning device may be shorter than the width of the table- and may be configured to clean one strip of the table at a time.

[00299] The surface cleaning device 100 may operate without a frame that is positioned above the panel - and thus is lower than frame based solutions. This reducing the shading effect of the surface cleaning device 100.

[00300] It should be noted that the pivot pole may be segments to segments - for example an upper segment and a lower segment- and different segments may be moved (for example rotated) by engines that reside in different parts of the surface cleaning device - for example one engine may be located at (or in proximate to) the upper wagon and another engine may be located at (or proximate to) the lower wagon. The segments may be of the same length or differ from each other by length. Figure 19 illustrates the pivot pole as including two segments 5(1) and 5(2) - each rotated by a different engine - 91 and 92 respectively. Movement mechanism unit 71 includes (or is proximate to) engine 91. Movement mechanism unit 72 includes (or is proximate to) engine 92.

[00301] It should be noted that the shaking pipes are not limiting examples of a motion delay element. A motion delay element may have a different shape than a pipe.

[00302] A motion delay element may actively catch the wiper (for example - by using clips or any gripping elements that perform a movement towards the wiper) and then release the wiper. Non-limiting examples of grabbing elements may be found in almost any robotic arm.

[00303] Figure 20 illustrates that the motion delay elements are robotic arms

- 406 and 406'. Robotic arm 406' is illustrated in a closed position while robotic arm 406 is in an open position. [00304] The surface cleaning device may include interfacing elements - such as rings, rails, protuberances, openings that may ease the holding of the surface cleaning device by a drone and/or a robotic arm and the like.

[00305] Figure 21 is a side view of the surface cleaning device 100, a table

101 and tracker or fixed support 102 that supports the table. Figure 21 illustrates that the upper wagon 3 moves along the upper end of the table (hence "upper" wagon) while the lower wagon 10 moves along the lower end of the table (hence "lower" wagon).

[00306] Figure 22 illustrates method 500.

[00307] Method 500 may include steps 510, 520 and 530.

[00308] Step 510 may include moving, using a motor, a first dust carrying member and a second dust carrying member over a path.

[00309] Step 510 may include:

a. Contacting the surface by the first dust carrying member while progressing at a first direction; and

b. following the contact with the surface, colliding by the first dust carrier with a shaking member thereby removing dust from the first dust carrying member;

c. partially blocking by the surface cleaning device, the dust removed from the first dust carrying member from progressing at a direction that is opposite to the first direction.

d. contacting the surface by the second dust carrying member while progressing at a first direction; and

e. following the contact with the surface, colliding by the second dust carrier with a shaking member thereby removing dust from the first dust carrying member;

f. partially blocking by the surface cleaning device, the dust removed from the second dust carrying member from progressing at a direction that is opposite to the first direction.

[00310] Method 500 may also include step 530 of moving a surface cleaning device in relation the surface.

[00311] Step 530 may be executed in parallel (with a certain overlap or in a staggered manner - even without overlap) to step 510. [00312] Each wiper may stretch along at least a majority of the length of the pivot pipe. Alternatively, multiple wipers may be much shorter than the pivot pipe. Multiple wipers may be arranged in rows, in a staggered manner or in any ordered or non-ordered manner to cover at least a majority of the pivot pope (or any other interfacing element that contacts the wipers).

[00313] In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the invention as set forth in the appended claims.

[00314] Moreover, the terms "front," "back," "top," "bottom," "over,"

"under" and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[00315] Those skilled in the art will recognize that the boundaries between blocks are merely illustrative and that alternative embodiments may merge blocks or circuit elements or impose an alternate decomposition of functionality upon various logic blocks or circuit elements. Thus, it is to be understood that the architectures depicted herein are merely exemplary, and that in fact many other architectures may be implemented which achieve the same functionality.

[00316] Any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality.

[00317] Furthermore, those skilled in the art will recognize that boundaries between the above described operations merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments.

[00318] However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

[00319] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'comprising' does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms "a" or "an," as used herein, are defined as one or more than one. Also, the use of introductory phrases such as "at least one" and "one or more" in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The same holds true for the use of definite articles. Unless stated otherwise, terms such as "first" and "second" are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

[00320] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.