Cleaning device and method for cleaning one or more solar panels

Abstract

Described is a cleaning device (1) for cleaning a solar panel (P), comprising: a mounting frame (11), elongated along a transverse direction (T) between a first end and a second end; a first movement wheel (121), connected to the first end of the frame (11); a second movement wheel (131), connected to the second end of the frame (11); an actuating unit, configured to provide a drive torque to the first movement wheel (121 ) or to the second movement wheel (131); a control unit, configured to control the actuating unit for instructing it in moving the cleaning device (1); a cleaning system. The cleaning system comprises: a scrubbing unit (14), interposed, along the transverse direction (T), between the first and the second movement wheels (121, 131) to come into contact with a working surface of the solar panel (P); a dispenser (15), which can be connected to a fuel supply tank (RS) and configured for dispensing a cleaning fluid towards the working surface (P1) of the solar panel (P). The first or the second movement wheels (121, 131) is configured to move the cleaning device (1 ) by means of the rolling friction which develops between the first or the second movement wheels (121, 131) and a respective surface on which the wheel is configured to rotate.

Description

[0001] DESCRIPTION

[0002] CLEANING DEVICE AND METHOD FOR CLEANING ONE OR MORE SOLAR PANELS

[0003] Technical field

[0004] This invention relates to a cleaning device for cleaning a solar panel and a method for cleaning a solar panel.

[0005] Background art

[0006] In the world of devices for cleaning solar panels there are various prior art solutions which are manual and which require the intervention of an operator, who, with a portable device which is used when necessary, cleans the solar panels. These systems and methods are, necessarily, subject to critical issues in terms of costs, flexibility, use of resources and efficiency.

[0007] Other solutions comprise installations of cleaning devices which perform the cleaning activities automatically. These systems, whilst they are faster and whilst not requiring a direct intervention by the maintenance technician, have the critical issue of requiring support infrastructures, and therefore very onerous and fixed installations which considerably reduce the flexibility of the system.

[0008] Examples of these solutions are those shown, for example, in documents JP2015150492A and CN209562500.

[0009] The first document, JP2015150492A, describes a solution wherein a movable carriage is guided and driven by a belt meshing system. Moreover, the system is particularly complex since it requires a transversal movement of the cleaning elements. Moreover, it is a not very reliable system, since the cleaning device is guided in such a way that, if it suffers impacts or thrusts, it could come out from the tracks and fall on the panels, irreparably ruining them.

[0010] Patent document CN209562500 suffers from the same problems as the one already described (heavy installation and with the intervention of further supporting infrastructure), but, in addition, it describes a solution which is very inefficient in terms of cleaning, with simple scraping brushes that, moreover, would risk breaking the panels.

[0011] Moreover, the system for moving the device on the panel is very complex.

[0012] There are also other prior art solutions which, however, have the same drawbacks, to a more or less onerous extent, and which are illustrated in the following patent documents: WO2012123979A1 , CN212216403, WO201 4203560A1 and AU2019349968A1.

[0013] Aim of the invention

[0014] The aim of this invention is to provide a cleaning mechanism and a method which overcome the above-mentioned problems of the prior art.

[0015] Said aim is fully achieved by the device and the method according to the invention as characterised in the appended claims.

[0016] According to an aspect of the invention, a cleaning device for cleaning a solar panel is provided.

[0017] The cleaning device comprises a mounting frame, elongated along a transverse direction between a first end and a second end.

[0018] The cleaning device comprises a first movement wheel. The first movement wheel is connected to the first end of the frame.

[0019] The cleaning device comprises a second movement wheel. The second movement wheel is connected to the second end of the frame.

[0020] The cleaning device comprises an actuating unit. The actuating unit includes a movement actuator. The movement actuator is configured to provide a drive torque to the first movement wheel or to the second movement wheel, for moving the cleaning device on the solar panel along a cleaning direction. For this reason, when the movement actuator is configured to actuate only one between the first and the second movement wheels, the other wheel not actuated acts only as a rotating support, with the wheel rotating in an idle fashion.

[0021] According to a particularly advantageous embodiment, the movement actuator comprises a first motor, configured to actuate the first movement wheel. Moreover, the movement actuator comprises a second movement unit, configured for actuating the second movement wheel.

[0022] Thus, both the first and the second movement wheels are provided with a respective drive torque.

[0023] The cleaning device comprises a control unit. The control unit is configured to control the actuating unit for instructing it in the movement of the cleaning device, along a cleaning direction perpendicular to the transverse direction.

[0024] The cleaning device comprises a cleaning system.

[0025] The cleaning system comprises a scrubbing unit. Preferably, the scrubbing unit is interposed, along the transverse direction, between the first and second movement wheels to make contact with a working surface of the solar panel. In fact, the first movement wheel slides on a first longitudinal side of the panel, the second slides on a second longitudinal side of the panel, whilst the scrubbing unit, which extends transversely, is in contact with the panel for cleaning it, in the zone between the first side and the seconds.

[0026] The cleaning system comprises a dispenser. The dispenser can be connected to a fluid supply tank. The dispenser is configured for dispensing a cleaning fluid towards the working surface of the solar panel.

[0027] The first or the second movement wheel is configured to move the cleaning device by means of the rolling friction which develops between the first or the second movement wheel and the respective first or second transverse end of the solar panel, respectively. The first movement wheel is configured for entering into contact with a respective rolling surface whilst the second movement wheel is configured for entering into contact with a respective rolling surface.

[0028] According to an embodiment, a first transverse end of the solar panel defines the rolling surface of the first movement wheel whilst a second transverse end of the solar panel, opposite the first transverse end, defines the rolling surface of the second movement wheel.

[0029] According to this possible embodiment, which is not the only possible one, the solution does not provide for additional infrastructures, for example specific tracks, chains or belts which must be connected close to the panel, thus making the device extremely flexible and easy to assemble, because it is directly mounted on the panel. On the other hand, this embodiment has the risk of breakage of the panels.

[0030] According to another advantageous embodiment, the first movement wheel is configured to make contact with an L-shaped profile positioned longitudinally at the transverse end of the solar panel. The second movement wheel is configured for entering into contact with a further L- shaped profile located longitudinally at the second transverse end of the solar panel, opposite the first transverse end. The first or the second movement wheel is configured to move the cleaning device by means of the rolling friction which develops between the first or the second movement wheel and the respective L-shaped profile positioned in the corresponding transverse ends of the panel, respectively.

[0031] This embodiment, whilst making the installation more onerous, guarantees a better guide and a reduced risk of damaging the panel.

[0032] According to an embodiment, there are a pair of L-shaped profiles at the ends of the panel, such as to guarantee the longitudinal movement of the system by means of the guide unit 4. According to an embodiment, the L- shaped profiles are positioned on the C-shaped clips for joining between the panel and the load-bearing structure, such as to guarantee a more fluid movement.

[0033] Advantageously, the system may be installed on plants with different inclinations (from 0 to 90 degrees of inclination of the solar panel with respect to the ground).

[0034] With this methodology the weight of the system is discharged in several points, balancing the load no longer on the panel but on the C-shaped joining clips. In addition, it is possible to install physical blocks at the start and end of stroke on the above-mentioned tracks, to prevent the system from escaping from the tracks.

[0035] According to an embodiment, the system comprises a pair of U-shaped profiles at the ends of the panel, such as to be able to guarantee the longitudinal movement of the system by means of the guide unit. In particular, said U-shaped profiles are positioned on the C-shaped joining clips between the panel and the load-bearing structure, such as to guarantee a more fluid movement and above all increase the degree of safety (as there are physical blocks at the start and end of stroke).

[0036] With this methodology the weight of the system is discharged in several points, balancing the load no longer on the panel but on the C-shaped joining clips.

[0037] The cleaning device comprises a guide system. The guide system includes a plurality of rolling elements. The rolling elements of said plurality of rolling elements rotate about respective axes perpendicular to the cleaning direction. The rolling elements of said plurality of rolling elements are configured to remain in contact with the panel or with the L- shaped or U-shaped profiles during the movement of the cleaning device along the cleaning direction.

[0038] In this way, the device is more stable during its movement.

[0039] Advantageously, the guide system comprises a group of transversal rolling elements, designed to rotate about an axis parallel to the transverse direction.

[0040] Moreover, according to a particularly high-performance embodiment, the guide system comprises a group of longitudinal rolling elements, configured to rotate about an axis perpendicular to the transverse direction.

[0041] The use of said longitudinal rolling elements enables the device to be firmly gripped to the panel or to the L-shaped or U-shaped profiles, such as to allow panel positioning in any orientation. Moreover, since the panel is equipped with friction rolling wheels, these rolling elements allow the device to be prevented from falling when it is positioned vertically. Generally speaking, therefore, the flexibility and solidity of the device increases.

[0042] Preferably, the rolling elements of the group of longitudinal rolling elements have a diameter greater than the rolling elements of the group of transverse rolling elements.

[0043] This guarantees a greater lateral hold and reliable gripping of the device to the panel.

[0044] According to an advantageous embodiment, the rolling elements of the group of longitudinal rolling elements have an adjustable position along the transverse direction. This allows the device to be positioned and, only then, to move the rolling elements towards the panel until they come into contact with each other, also adjusting the force applied by them on the panel. In this way, the force can be adapted to the weight or to the orientation of the device.

[0045] The scrubbing unit comprises a cleaning rod, rotatable relative to the mounting frame. The scrubbing unit comprises a scrubbing element, keyed on the cleaning rod for rotating on the working surface of the solar panel.

[0046] Advantageously, the actuating unit comprises a scrubbing actuator, configured to rotate the cleaning rod of the scrubbing unit.

[0047] In this way, the scrubbing element rotates independently of the movement and may, for example, be rotated more in zones which are dirtier. This increases the effectiveness of cleaning and the flexibility of the device.

[0048] According to an embodiment, the dispenser comprises a duct. The duct is preferably elongated along the transverse direction. The duct includes a plurality of nozzles, distributed along the transverse direction. The nozzles are oriented in such a way as to dispense the cleaning fluid towards the working surface of the solar panel.

[0049] According to an embodiment, the device comprises a detection unit. The detection unit includes one or more of the following sensors:

[0050] - a torque sensor, configured for detecting a torque signal, representing a torque delivered by the movement actuator;

[0051] - an optical sensor, configured for detecting the presence of one or more obstacles on the solar panel;

[0052] - one or more inspection video cameras, configured to capture image data representing a state of cleanliness of the working surface of the solar panel.

[0053] - level sensors (that is to say / for example, detection sensors for a sentina pump), designed for automatically detecting the level of cleaning fluid present in the tanks of the cleaning unit.

[0054] According to an embodiment, the control unit is configured to receive the torque signal from the torque sensor. The control unit is configured for comparing the torque value derived from the torque signal with a predetermined threshold value. The control unit is configured to reverse an advancement direction of the device in response to the exceeding, by the detected torque value, of the predetermined threshold value.

[0055] According to an embodiment, the level sensor is configured for sending a level signal to the control unit. The control unit is configured for comparing the level signal with a threshold value, below which the control unit is programmed for commanding a return of the device for refilling the tank.

[0056] According to an aspect of the invention, the control unit is configured for receiving the image data from said one or more video cameras.

[0057] The control unit is configured for processing the image data for deriving information regarding the cleanliness of the solar panel.

[0058] The control unit is configured to derive, on the basis of the information regarding the cleanliness of the solar panel, a value of a control parameter.

[0059] The control unit is configured to receive the signal for detecting the level of liquid present in the tanks.

[0060] The control unit is configured for comparing the value of the control parameter with a predetermined threshold value.

[0061] The control unit is configured for starting a cleaning cycle by the device when the predetermined threshold value is exceeded by the value of the derived control parameter. According to an aspect of the invention, a cleaning unit for cleaning a solar panel is provided.

[0062] The cleaning unit comprises a cleaning device according to one or more of the features described in the invention.

[0063] The cleaning unit comprises a fluid supply tank, connected to the dispenser of the device for supplying the latter with a flow of cleaning fluid. According to an embodiment, the cleaning unit comprises a parking platform. The parking platform is configured to be connected to a longitudinal end of the solar panel in a position outside the working surface of the solar panel. Said cleaning device is configured to be positioned on the parking platform between one cleaning cycle and the next.

[0064] The parking platform comprises a covering wall, for covering the device when it is at rest.

[0065] On its lower surface (for supporting the device), the parking platform comprises an extension of the tracks, in such a way as to create a continuity of the tracks when the device arrives at the end of the panel, from the part on which the parking platform is positioned.

[0066] According to an embodiment, the cleaning unit comprises a parking platform. According to an embodiment, the cleaning unit comprises a reel, about which the flexible duct is rolled. Said flexible duct connects the fluid supply tank to the dispenser.

[0067] According to an aspect of the invention, a unit for generating electricity from solar energy is provided.

[0068] The generating unit comprises a solar panel. The solar panel includes a working surface, configured to receive solar radiation and to convert the solar energy into electricity.

[0069] The generating unit comprises the cleaning device according to any one of the features described in this invention. The generating unit comprises the cleaning unit according to any one of the features described in the invention. According to an embodiment, the system is powered by direct current. It can be derived from an accumulation system (batteries) provided in the photovoltaic system already present.

[0070] According to an aspect of the invention, a method is provided for cleaning a solar panel.

[0071] The method comprises a step of preparing the cleaning device according to one or more of the features described in the invention.

[0072] According to an embodiment of the method, the latter comprises a step of positioning the device on the solar panel, with the first movement wheel in contact with a respective rolling surface positioned at the first transverse end of the solar panel and with the second movement wheel in contact with a respective rolling surface positioned at the second transverse end of the solar panel.

[0073] According to an embodiment, said rolling surface is defined by a transversal edge of the panel, so, the first movement wheel is in direct contact with the first transverse end of the solar panel and the second movement wheel is in direct contact with the second transverse end of the solar panel.

[0074] Alternatively, according to a particularly advantageous embodiment, the rolling surface on which the first movement wheel rotates is defined by an “L” or “U”-shaped profile which is connected to a supporting structure of the panel at a first transversal end of the panel, and the rolling surface on which the second movement wheel rotates is defined an “L” or “U” -shaped profile which is connected to a supporting structure of the panel at a second transversal end of the panel.

[0075] The method comprises a step of actuating the first movement wheel and / or the second movement wheel by means of a movement actuator, which imparts a drive torque to the first movement wheel and / or to the second movement wheel.

[0076] The method comprises a step of moving the cleaning device on the solar panel or on the “L” or “U”-shaped profiles, along a cleaning direction, perpendicular to the transverse direction.

[0077] The method comprises a step of controlling, using a control unit, the actuating unit for instructing it in the step of moving the cleaning device.

[0078] The method comprises a step of removing dirt on a working surface of the solar panel, using a scrubbing unit, interposed, along the transverse direction, between the first and second movement wheels.

[0079] The method comprises a step of dispensing a cleaning fluid towards the working surface of the solar panel, by means of a dispenser connected to a fluid supply tank.

[0080] The method comprises a step of dispensing a cleaning fluid towards the working surface of the solar panel. The dispensing step is performed using a group of tanks inside the cleaning system (master / slave) provided with an electric pump. The above-mentioned tanks will refill during the refilling cycle, when the cleaning device is in the refilling cycle.

[0081] Brief description of the drawings

[0082] This and other features will become more apparent from the following description of a preferred embodiment of the invention, illustrated by way of non-limiting example in the accompanying tables of drawings, in which:

[0083] - Figures 1A and 1 B schematically illustrate a side view of a cleaning unit for cleaning a solar panel;

[0084] - Figure 2 schematically illustrates a plan view of the cleaning unit of Figure 1A;

[0085] - Figure 3 is a perspective view of a cleaning unit for cleaning a solar panel;

[0086] - Figure 4 is a perspective view of a cleaning device of the unit of Figure 4;

[0087] - Figure 5 is a view from below of the device of Figure 5;

[0088] - Figure 6 is a side view of the device of Figure 5;

[0089] - Figure 7 illustrates a parking platform and a cleaning device which can be housed inside it;

[0090] - Figures 8A and 8B show a first side view and a second side view of an embodiment of a cleaning device according to this invention, respectively.

[0091] Detailed description of preferred embodiments of the invention

[0092] With reference to the accompanying drawings, the numeral 100 denotes a cleaning unit for cleaning one or more solar panels P.

[0093] Before entering into the merits of the cleaning unit 100, some features of the solar panel P are described below, in such a way as to be able to suitably describe how these integrate with the components of the cleaning unit 100.

[0094] The solar panel P comprises a working surface P1 , which is configured to receive the solar radiation and convert the solar energy into electricity. In short, the exposure of this surface determines the efficiency of the solar panel.

[0095] The solar panel P comprises a first longitudinal side panel P2 which extends along a longitudinal direction L and is alongside the working surface P1. The solar panel P comprises a second longitudinal side panel P3 which extends along a longitudinal direction L, parallel to the first longitudinal side panel P2, alongside the working surface P1 on the opposite side of the first longitudinal side panel P2.

[0096] The solar panel P is generally supported by a supporting system P4, positioned below the panel P to support it in its orientation (fixed or variable).

[0097] According to an embodiment, in which there are several panels P side by side along a transverse direction T, perpendicular to the longitudinal direction L, between the second longitudinal side panel P3 of a panel P and the first longitudinal side panel P2 of an adjacent panel P there is a distance alongside each other.

[0098] The cleaning unit 100 comprises a cleaning device 1 , configured to clean the working surface P1 of the panel P. The cleaning unit 100 comprises a parking platform 2.

[0099] The cleaning unit 100 comprises a fluid supply unit 101 , configured for feeding a cleaning fluid to the cleaning device 1 .

[0100] According to an embodiment, the parking platform 2 comprises an outer casing 21 , including a bottom wall 211 , two side walls 212 and an upper wall 213. The upper wall 213 allows the cleaning device to be protected when it is positioned in the parking platform 2.

[0101] On the bottom wall 211 , it is possible to provide a plurality of tracks 211 B, which receive corresponding wheels for moving the cleaning device 1 when this enters the parking platform 2. Said plurality of tracks is aligned, longitudinally, with a corresponding plurality of tracks 41 , 42 positioned laterally to the panel P.

[0102] The cleaning unit 100, according to an embodiment, comprises a guide unit 4. During the movement of the cleaning device 1 , the cleaning device 1 moves on the panel or along tracks positioned transversely to the panel P in order to clean the panel (as explained in more detail below).

[0103] In effect, according to an embodiment, the cleaning device 1 is interfaced directly with the panel P, in particular with the first and second longitudinal panels P2, P3 of the panel P.

[0104] According to other embodiments, on the other hand, the cleaning device 1 is interfaced with the guide unit 4 which, in turn, is connected directly to the panel P, in particular with the first and second longitudinal side panels P2, P3 of the panel P.

[0105] According to an embodiment, the guide unit 4 comprises a pair of tracks 41 , 42, each connected (with mechanical elements, screws or industrial glues) to the first and to the second longitudinal side panels P2, P3, respectively.

[0106] According to this embodiment, the cleaning device 1 rests on the pair of tracks 41 , 42.

[0107] According to other solutions, the guide unit 4 comprises a pair of C-shaped connectors 43, 44, configured for connecting the panel P with the supporting system P4. Subsequently, the cleaning device 1 can be positioned directly above the pair of connectors or, even more advantageously, each track of said pair 41 , 42 can be positioned above a respective C-shaped connector 43, 44.

[0108] According to an embodiment, the parking platform 2 is located, along the longitudinal direction L, upstream or downstream of the panel P. In this way, when the cleaning device 1 is not cleaning the panel P, this may be set at rest on the parking platform 2, in such a way as not to be above the working surface P1 and therefore not reduce the efficiency of the panel P.

[0109] It should be noted that this invention has two embodiments with regard to hydraulic and electrical power supply.

[0110] According to a first embodiment, which may be referred to as “online supply”, the cleaning device 1 is powered electrically and hydraulically in a continuous fashion, that is to say, it is directly connected to an external electricity supply and / or water supply by respective electrical cables and / or hydraulic ducts. On the other hand, according to a further embodiment, which can be defined as “refilling”, the cleaning device 1 comprises one or more of the following features:

[0111] - a tank RS, configured to contain a quantity of cleaning fluid which can be used by the device to perform a predetermined number of cleaning cycles. According to a second embodiment, the tank RS comprises a first tank RS1 (master) and a second tank RS2 (slave). The first tank RS1 is refilled with water when the system (1 ) is in the refilling cycle, by using non-return valves. The second tank RS2 comprises an electric pump which, when started, dispenses liquid to the pipe 151. The second tank RS2 comprises a level sensor, for assessing the quantity of liquid present and communicating it to the control unit.

[0112] The first and the second tanks RS1 , RS2 are positioned, along a direction perpendicular to the transverse and longitudinal directions, between the cover 144 and the first and / or second dispensers 145, 146. The first and the second tank RS1 , RS2 are connected by a flexible hose to the dispensing manifold 151 of the dispenser 15.

[0113] - a battery pack PB, configured to power the actuators of the cleaning device 1 .

[0114] According to a second embodiment, the battery pack PB comprises a plurality of batteries, preferably two batteries PB1 , PB2, connected in parallel. Said batteries are preferably charged using a wireless module 22 (preferably equipped with a circuit upstream to avoid overvoltages). The battery pack PB is connected to the control unit.

[0115] The two batteries PB1 , PB2 are positioned, along a direction perpendicular to the transverse and longitudinal directions, between the cover 144 and the first and / or second dispensers 145, 146.

[0116] According to an embodiment with online supply, the fluid supply unit 101 comprises hydraulic (or electrical) conduits 101 A, which are connected to the cleaning device 1. Moreover, the fluid supply unit 101 comprises a tank 101 B, containing cleaning fluid.

[0117] Lastly, moreover, the fluid supply unit 101 comprises a winding reel 101 C, configured for elastically withdrawing the hydraulic conduits 101 A when the cleaning device 1 moves towards and unwinding them when the cleaning device 1 moves away.

[0118] According to the embodiment with a refilling supply, the parking platform 2 comprises a hydraulic coupling 21 , connected to the tank 101 B. The hydraulic coupling 21 is configured to engage with a corresponding hydraulic coupling of the tank RS, in such a way as to transfer the cleaning fluid. The hydraulic coupling 101 B comprises a non-return valve, configured to be opened in response to a coupling between the hydraulic coupling 21 and the hydraulic coupling of the tank RS.

[0119] In particular, it is preferable that, when the cleaning device 1 reaches its rest position on the parking platform 2, the two hydraulic couplings are coupled and, in response to said coupling, the non-return valve opens allowing a filling of the tank RS until the pressures are equalised. When the cleaning device 1 restarts, the uncoupling between the couplings determines the closing of the non-return valve. According to an embodiment, the tank RS also comprises a respective non-return valve, on the connector, mounted to prevent possible undesired escape of liquid (increase in the safety of the device). In addition or alternatively, the tank RS comprises a solenoid valve (preferably 12 / 24V) for pressurising the cleaning liquid. In addition or alternatively, the tank RS comprises a liquid sensor, for assessing the level of the cleaning liquid present in the tank RS.

[0120] According to the embodiment with refilling supply, the parking platform 2 comprises an electric charger 22. The electrical charger, according to an embodiment, is a wireless charger, for example with electromagnetic induction, which allows the battery pack PB to be recharged when the latter falls inside the electromagnetic field, that is to say, when the cleaning device 1 is at rest on the parking position 2.

[0121] Alternatively, it is also possible to consider a contact recharging, for example comprising a socket on the parking platform 2 and a rigid plug on the cleaning device 1 , in such a way that, when the cleaning device 1 is in its rest position on the parking platform 2, the plug is inserted automatically in the socket.

[0122] The embodiment with online supply simplifies the parking platform 2 but obviously makes the movement of the device 1 less practicable, which must in any case manage cables and hydraulic conduits during its cleaning stroke. On the other hand, the embodiment with refilling supply, even though it is more complex initially, guarantees to the cleaning device a greater agility and a freedom of motion. Moreover, this embodiment also ensure, if there are problems with the external electrical or fluid supply, that the device 1 has a relative operating autonomy, which is a very important operating buffer.

[0123] With regard to the cleaning device 1 , the latter comprises a frame 11. The frame 11 comprises a first rib 111 . The frame comprises a second rib 1 12.

[0124] The frame 11 comprises one or more mounting beams 113, elongated along a longitudinal direction L between a first end 113A and a second end 113B. The first end 113A of said mounting beam 113 is connected to the first rib 111 and the second end 113B of said mounting beam 113 is connected to the second rib 112.

[0125] The frame 11 comprises a cover 114 (144 in Figure 6), configured to cover the components of the cleaning device 1 , preventing these from getting wet. Preferably, the cover 114 comprises sloping walls for the outflow of any fluids which fall on the device 1 .

[0126] The battery pack PB and the tank RS (according to the embodiment in which they are present) are connected (supported, constrained) (for example by U-shaped supports) 20 on the mounting beam 113 or above the cover 114, adequately insulated from the outside environment.

[0127] In order to make the mounting beam 113 more rigid, according to some embodiments there is a reinforcement rib 113C, interposed, along the longitudinal direction L, between the first and the second ends 113A, 113B of the mounting beam 113.

[0128] The cleaning device 1 comprises a first movement unit 12. The first movement unit 12 comprises a first movement wheel 121. The first movement unit 12 comprises a respective shaft 122, on which is keyed the first movement wheel 121 , in such a way as to rotate as one with the shaft 122. The shaft 122 is also supported on the first rib 111 so as to be able to rotate freely relative to it (for example, a common radial ball bearing is used). The first movement unit 12 comprises a first motor 123, configured to provide a drive torque to the first movement wheel 121 , by means of the shaft 122.

[0129] The axis of rotation of the first movement wheel 121 is parallel to the transverse direction T.

[0130] Said first movement wheel 121 is a rolling wheel which develops the movement due to the rolling friction. The first movement wheel 121 may make contact with the first longitudinal edge P2 of the panel P, with the track 41 or with the track 41 when it is above the C-shaped connector.

[0131] Preferably, the first movement wheel 121 is made of a deformable plastic material, in such a way as to increase the contact surface of the wheel and, therefore, also the thrust provided by the wheel 121.

[0132] According to an embodiment, the first movement unit 12 comprises a first pair of transversal wheels 124. Each of said transversal wheels 124 rotates about a respective axis of rotation spaced along the longitudinal direction L and parallel to the transverse direction T. Obviously, solutions may also be provided with a single transversal wheel 124.

[0133] It should be noted that according to a preferred embodiment, the transversal wheel 124, 134 and the respective movement wheel 121 , 131 are aligned longitudinally, that is to say, not offset. This increases the compactness of the device 1. Moreover, this allows the movement wheels 121 , 131 and the transversal wheels 124, 134 to slide in the corresponding track 41 , 42.

[0134] Said first pair of transversal wheels 124 is a pair of idle, non-driving wheels, which rotate and guide the device 1 during its movement determined by the thrust due to the first movement wheel 121 .

[0135] Said first pair of transversal wheels 124 is supported on the first rib 111 .

[0136] Said pair of transversal wheels 124 may come into contact with the first longitudinal edge P2 of the panel P, with the track 41 or with the track 41 when it is above the C-shaped connector.

[0137] Preferably, said pair of transversal wheels 124 are positioned, along a direction perpendicular to the transverse direction T and to the longitudinal direction L, below the first rib 111.

[0138] According to an embodiment, the first movement unit 12 comprises a first pair of longitudinal wheels 125. Each of said longitudinal wheels 125 rotates about a respective axis of rotation spaced along the longitudinal direction L and perpendicular to the transverse direction T. Clearly, solutions with a single longitudinal wheel 125 can also be provided.

[0139] Said first pair of longitudinal wheels 125 is a pair of idle, non-driving wheels, which rotate and guide the device 1 during its movement determined by the thrust due to the first movement wheel 121 .

[0140] Said first pair of longitudinal wheels 125 is supported on the first rib 111 . Said pair of longitudinal wheels 125 may come into contact with the first longitudinal edge P2 of the panel P, with the track 41 or with the track 41 when it is above the C-shaped connector.

[0141] It should be noted that said pair of longitudinal wheels 125 come into contact with a surface perpendicular to the solar panel P, that is to say, a surface perpendicular to the transverse direction T.

[0142] In effect, the thrust of the longitudinal wheels 125 allows the device 1 to be maintained.

[0143] In this regard, the movement unit 12 comprises an adjustment system, configured for adjusting the transversal position of the pair of longitudinal wheels 125. For example, according to an embodiment, said first pair of longitudinal wheels 125 is connected to the first rib 111 , in a first portion. The first portion is movably connected to the remaining part of the first rib 111 , to move along the transverse direction T. For example, but without restricting the scope of the invention, the first portion might be connected by a adjustment screw, the rotation of which causes a transversal movement of the first portion and, consequently, of the first pair of longitudinal wheels 125 connected thereto.

[0144] In this way, it is possible to increase the flexibility of the device 1 , since the width of the device can be adapted to panels with slight transversal differences. Even more importantly, the adjustment of the first pair of longitudinal wheels 125 allows calibration of the force they apply on the walls of the solar panel P or on the “L” or “U”-shaped profiles in such a way as to support well the weight of the device 1 (also depending on the orientation of the solar panel P which, the more vertical it is, the more it requires a support).

[0145] Preferably, said pair of longitudinal wheels 125 are positioned, along a direction perpendicular to the transverse direction T and to the longitudinal direction L, below the first movement wheel 121 and below the first pair of transversal wheels 124.

[0146] The cleaning device 1 comprises a second movement unit 13. The second movement unit 13 is positioned on the second rib 112, and thus on the second transversal end 11 B of the frame 11 .

[0147] The second movement unit 13 comprises a second movement wheel 131. The second movement unit 13 comprises a respective shaft 132, on which is keyed the second movement wheel 131 , in such a way as to rotate as one with the shaft 132. The shaft 132 is also supported on the second rib 112 so as to be able to rotate freely relative to it (for example, a common radial ball bearing is used). The second movement unit 13 comprises a second motor 133, configured to provide a drive torque to the second movement wheel 131 , by means of the shaft 132.

[0148] The axis of rotation of the second movement wheel 131 is parallel to the transverse direction T.

[0149] Said second movement wheel 131 is a rolling wheel which develops the movement due to the rolling friction. The second movement wheel 131 may come into contact with the second longitudinal edge P3 of the panel, with the track 42 or with the track 42 when it is above the C-shaped connector.

[0150] Preferably, the second movement wheel 131 is made of a deformable plastic material, in such a way as to increase the contact surface of the wheel and, therefore, also the thrust provided by the wheel 131 .

[0151] According to an embodiment, the second movement unit 13 comprises a second pair of transversal wheels 134. Each of said transversal wheels 134 rotates about a respective axis of rotation spaced along the longitudinal direction L and parallel to the transverse direction T. Clearly, solutions with a single transversal wheel 134 can also be provided.

[0152] Said second pair of transversal wheels 134 is a pair of idle, non-driving wheels, which rotate and guide the device 1 during its movement determined by the thrust due to the second movement wheel 131 .

[0153] Said second pair of transversal wheels 134 is supported on the second rib 112.

[0154] Said pair of transversal wheels 134 may come into contact with the second longitudinal edge P3 of the panel P, with the track 42 or with the track 42 when it is above the C-shaped connector.

[0155] Preferably, said pair of transversal wheels 134 are positioned, along a direction perpendicular to the transverse direction T and to the longitudinal direction L, below the second rib 112.

[0156] According to an embodiment, the second movement unit 13 comprises a second pair of longitudinal wheels 135. Each of said longitudinal wheels 135 rotates about a respective axis of rotation spaced along the longitudinal direction L and perpendicular to the transverse direction T. Clearly, solutions with a single longitudinal wheel 135 can also be provided.

[0157] Said second pair of transversal wheels 135 is a pair of idle, non-driving wheels, which rotate and guide the device 1 during its movement determined by the thrust due to the second movement wheel 131 .

[0158] Said second pair of longitudinal wheels 135 is supported on the second rib 112.

[0159] Said second pair of longitudinal wheels 135 may come into contact with the second longitudinal edge P3 of the panel P, with the track 42 or with the track 42 when it is above the C-shaped connector.

[0160] It should be noted that said pair of longitudinal wheels 135 come into contact with a surface perpendicular to the solar panel P, that is to say, a surface perpendicular to the transverse direction T.

[0161] In effect, the thrust of the longitudinal wheels 135 allows the device 1 to be maintained.

[0162] In effect, the combination of the thrust of the first pair of longitudinal wheels 125 and of the second pair of longitudinal wheels 135 allows the device 1 to be kept gripped.

[0163] In this regard, the second movement unit 13 comprises an adjustment system, configured for adjusting the transversal position of the second pair of longitudinal wheels 135. For example, according to one embodiment, said second pair of longitudinal wheels 135 is connected to the second rib 112, in a respective first portion. The first portion is movably connected to the remaining part of the second rib 112, to move along the transverse direction T. For example, but without restricting the scope of the invention, the first portion might be connected by a adjustment screw, the rotation of which causes a transversal movement of the first portion and, consequently, of the second pair of longitudinal wheels 135 connected thereto.

[0164] The adjustment of the first and second pairs of longitudinal wheels 125, 135 allows calibration of the force they apply on the walls of the solar panel P or on the track 42, in such a way as to well support the weight of the device 1 (also depending on the orientation of the solar panel P which, the more it is positioned vertically, the more it requires a support). Preferably, said second pair of longitudinal wheels 135 are positioned, along a direction perpendicular to the transverse direction T and to the longitudinal direction L, below the second movement wheel 131 and below the second pair of transversal wheels 134.

[0165] The cleaning device 1 comprises a scrubbing unit 14. The scrubbing unit 14 is interposed, along the transverse direction T, between the first and second movement wheels 121 , 131 to make contact with a working surface of the solar panel P. The scrubbing unit 14 is interposed, along the transverse direction T, between the first and the second rib 111 , 112.

[0166] The scrubbing unit 14 comprises a first cleaning rod 141 , connected to (supported on, supported by bearings on) the first rib 111 and to the second rib 112. According to an embodiment, the scrubbing unit 14 comprises a second cleaning rod 142, connected to (supported on, supported by bearings on) the first rib 111 and to the second rib 112. The first and the second cleaning rods 141 , 142 are spaced along the longitudinal direction L, so as to make successive cleaning passes on the working surface of the panel P.

[0167] The scrubbing unit 14 comprises a first scrubbing actuator 143. The first scrubbing actuator 143 is connected to the first cleaning rod 141 to place it in rotation about an axis of rotation parallel to the transverse direction T.

[0168] The scrubbing unit 14 comprises a second scrubbing actuator 144. The second scrubbing actuator 144 is connected to the second cleaning rod 141 to place it in rotation about an axis of rotation parallel to the transverse direction T.

[0169] According to this embodiment, the first and the second scrubbing actuators 143, 144 may both be positioned at the end of the respective cleaning rods 141 , 142 which are on the first rib 111 or on the second rib 112. There is nothing to prevent the first scrubbing actuator 143 from being on the first rib and the second scrubbing actuator 144 from being on the second rib (for example, to optimise the dimensions).

[0170] According to an embodiment, the scrubbing unit 14 comprises, for each of said first and second cleaning rods 141 , 142, a corresponding first and second scrubbing element 145, 146.

[0171] Said first and second scrubbing elements 145, 146 are keyed on the respective first and second cleaning rods 141 , 142.

[0172] According to an embodiment, said first and second scrubbing elements 145, 146 are cleaning brushes, having a plurality of cleaning fingers, configured to come into contact with the working surface of the panel P, when they rotated by the respective first and second scrubbing actuators 143, 144.

[0173] According to an embodiment, the device 1 comprises a first dispenser 15. The dispenser 15 comprises a dispensing manifold 151 , extending along the transverse direction T between a first end 151 , connected to the frame at its first end, and a second end 151 B, connected to the frame at its second end. In this way, the dispensing manifold 151 extends along the entire transversal width of the panel P.

[0174] The dispenser 15 comprises a plurality of dispensing nozzles 152, distributed (preferably in a homogeneous manner) along the dispensing collector 151 .

[0175] The dispensing nozzles 152 are oriented in a direction having at least one component perpendicular to the transverse direction T and longitudinal direction L, in a direction oriented on the opposite side of the cover, in such a way as to dispense the cleaning fluid coming from the tank RS towards the panel P. Preferably, the dispensing nozzles 152 are oriented along a dispensing direction, which is inclined relative to the direction perpendicular to the transverse direction T and to the longitudinal direction L in such a way as to project the jet of cleaning fluid in a direction concordant with the advancement direction of the device 1 , in such a way that, when the scrubbing unit 14 passes on the panel P, the cleaning fluid is already present.

[0176] According to an embodiment not illustrated in the accompanying drawings, in order to use every stroke of the device 1 with continuous dispensing of cleaning fluid, it is possible to provide a system for adjusting the inclination of the nozzles 152, for example by means of a controlled rotation (for example by an angle of between 0 and 180°) of the dispensing manifold 151.

[0177] Alternatively, there may be a second dispensing manifold, fixed and with the respective nozzles oriented in the opposite direction to that of the nozzles 152. According to this embodiment, the control unit of the device may selectively dispense from the first or from the second dispensing manifold depending on the advancement direction of the device 1 .

[0178] According to the solutions wherein the device 1 extends on several panels placed side by side transversally, the device 1 may comprise a central rib 115, on which is positioned a third movement wheel 115A actuated by a corresponding third motor 115B. Said third movement wheel 115A rotates on the second longitudinal side panel of the first panel and on the first longitudinal side panel positioned alongside. A third pair of transversal wheels 115C can also be provided on the central rib 115.

[0179] It should be noted that, according to an embodiment and in the presence of several panels alongside each other, the device preferably comprises an l-shaped or T-shaped profile to be connected to the C-shaped profile (the one which connects the panel to the supporting structure), on which there is the third movement wheel 115A.

[0180] Moreover, according to these solutions, the first and second cleaning rods 141 , 142 each comprise a first and a second portion. The first portion of the first and second cleaning rods 141 , 142 is connected to the first rib 111 and to the central rib 115 whilst the second portion of the first and second cleaning rods 141 , 142 is connected to the central rib 115 and to the second rib 112.

[0181] In this case, each portion of the cleaning rods 141 , 142 is actuated by a respective scrubbing actuator. Therefore, if there are two portions, the device 1 is equipped with four scrubbing actuators.

[0182] This may be reproduced in a modular fashion on the basis of the number of panels which are positioned side by side transversely, providing additional central ribs and additional portions of cleaning rods.

[0183] The system is therefore highly flexible and modular, in such a way as to greatly simplify the design and the adaptation to the various energy generation systems.

[0184] Having described in detail the device 1 , a detailed description is given below of how the latter is used for cleaning the panel P.

[0185] In this regard, it should be noted that the device 1 comprises a control unit, configured to send and receive signals representing commands to be supplied to the components of the device 1 and parameters received from sensors present in the device 1 , respectively.

[0186] More specifically, the control unit is configured to send control signals to the first motor 123 and to the second motor 133 for instructing them to move the first and the second movement wheels 121 , 131 , respectively. The device 1 comprises a pump, configured for pressurising the cleaning fluid dispensed by the nozzles 152.

[0187] The control unit is configured for sending control signals to the pump, for instructing it in dispensing the cleaning fluid, in particular for adjusting the pressure and / or the dispensing flow rate. The control unit is configured for sending control signals to the first and to the second scrubbing actuators 143, 144, for instructing them to rotate the first and the second cleaning rods 141 , 142, respectively.

[0188] For this reason, when a cleaning cycle is started, the control unit commands a movement of the device 1 along the longitudinal direction L and / or a rotation of the first and the second cleaning rods 141 , 142 and / or a dispensing of the cleaning fluid.

[0189] According to a simpler embodiment, the control unit is programmed for starting a cleaning cycle wherein the pump for dispensing the cleaning fluid, the first and the second motors 123, 133 and the first and the second scrubbing actuators 143, 144 are operated in an dependent manner (synchronised with each other in a predetermined mode). This simplifies the control but reduces the overall flexibility of the system.

[0190] On the other hand, according to a more high performance solution, the control unit controls the pump for dispensing the cleaning fluid, the first and the second motors 123, 133 and the first and second scrubbing actuators 143, 144 independently. This guarantees some important advantages, for example, if the panel were dirty only in one zone, one could consider moving the device to that longitudinal position and then operating the pump for dispensing the cleaning fluid together with the first and the second motors 123. This allows a reduction in the consumption of fluid and energy, in general.

[0191] An important issue also concerns the safety of the device. In this regard, the device 1 comprises a detection unit. The detection unit is configured for detecting operating parameters relating to the operation of the device 1 , which may be processed by the control unit for deriving control signals. According to an embodiment, the detection unit comprises one or more of the following sensors:

[0192] - one or more video cameras;

[0193] - an optical sensor;

[0194] - a level sensor (similar to a sentina detection pump sensor) - a distance sensor;

[0195] - a torque sensor, for each actuator of the device 1 (that is to say, for the pump for dispensing cleaning fluid, first and second motors 123, 133 and first and second scrubbing actuators 143, 144).

[0196] The control unit is configured for comparing the torque value received by the various torque sensors with a threshold value, in such a way as to interrupt the supply of torque for values greater than the threshold value. This prevents, if there are obstacles or blocks of the device 1 , the torque from being continued to be dispensed, with the risk of breaking the panel P or the device 1.

[0197] In order to also prevent this event, the control unit is programmed to receive control signals from said one or more video cameras and / or from said optical sensor and / or said distance sensor. The control unit processes the control signals and derives information regarding the presence or absence of obstacles in the cleaning path of the device 1 . Based on said information, the control unit generates the control signals, to block the actuators if there is the risk of colliding with obstacles.

[0198] In terms of the control of the device 1 , it is also important to assess how to recognise when the device 1 has reached the end of stroke position. In this regard, there may be various modes.

[0199] According to a first mode, the device 1 comprises an end of stroke plate, on which the device 1 collides when it reaches the end of the panel P. When an increase in the drive torque is detected by the device 1 , the control unit derives the end of stroke position and commands a reversal of the movement of the first and second motors 123, 133.

[0200] In a second mode, the control unit receives from the optical sensor and / or from the distance sensor control signals representing a distance of the device 1 from the end of stroke plate. When the distance falls below a limit value, the control unit derives a reaching, by the device 1 , of the end of stroke position and commands a reversal of the motion of the first and the second motors 123, 133. These two modes are the ones that combine practicality and safety, but they can still create problems, because they might recognise an obstacle such as the end of stroke.

[0201] In a third mode, the control unit is programmable by inserting an end of stroke distance, representing the length of the stroke to be travelled on the panel P. According to this embodiment, the device 1 comprises a distance sensor (for example an encoder on the movement wheels) which sends distance signals to the control unit, representing a distance travelled by the device 1 in a predetermined advancement direction. When the distance travelled by the device reaches the set end of stroke distance value, the control unit commands a reversal of the motion of the first and second motors 123, 133.

[0202] Lastly, according to a particularly advantageous mode, the control unit uses the video cameras to recognise the end of stroke position. According to this embodiment, the end of stroke plate comprises a graphical reference, which is recognisable by said one or more video cameras. In particular, the control unit is programmed, on the basis of the image data which it receives from said one or more video cameras, to derive a distance of the device 1 from the end of stroke plate. For example, but without limiting the scope of the invention, the value of the reference is proportional to its distance from the device 1. For this reason, once calibrated, the control unit is able to recognise the distance of the device 1 from the end of stroke plate. When the distance falls below a limit value, the control unit derives a reaching, by the device 1 , of the end of stroke position and commands a reversal of the motion of the first and the second motors 123, 133.

[0203] This makes it possible to distinguish an obstacle (which is dangerous for safety) from the end of stroke and therefore combines the two needs of safety and control of the end of stroke in a very efficient manner.

[0204] A further aspect of the control of the device 1 relates to its starting and the logic with which this occurs. Also according to this aspect, the invention provides different embodiments.

[0205] According to a simpler embodiment, the device 1 can be started manually, with the input of an operator. In this regard, the device 1 comprises a pushbutton for starting the cleaning cycle, which may be selected in-situ. In addition or alternatively, the device 1 comprises a remote communication module, configured for connecting remotely with a control station. By means of the remote communication module, an operator may communicate with the control unit, for sending to it a signal for starting the cleaning cycle from a remote position.

[0206] There are also automatic starting modes of the cleaning cycle.

[0207] According to this mode, the control unit is programmed to receive status data, representing a cleanliness of the panels. Said status data is detected, for example, by said one or more video cameras. Alternatively or in addition, said status data is detected by a drone, configured to inspect the cleanliness of the panels, flying over the panels P with a predetermined frequency.

[0208] The control unit is programmed to compare the status data with reference status data and to derive, based on said comparison, the cleanliness of the panel P, to understand if it is dirty at a level such as to have to start a new cleaning cycle.

[0209] According to other modes, the control unit is programmed to start a cleaning cycle at a predetermined frequency.

[0210] Preferably, the control unit is programmed for starting a cleaning cycle at a time when the panel P is not exposed to sunlight, so as not to reduce the overall efficiency of the system for generating the energy (for example during night time).

Claims

CLAIMS1. A cleaning device (1 ) for cleaning a solar panel (P), comprising:- a mounting frame (11 ), elongated along a transverse direction (T) between a first end and a second end;- a first movement wheel (121 ), connected to the first end of the frame (11 ), and a second movement wheel (131 ), connected to the second end of the frame (11 );- an actuating unit, including a movement actuator (123, 133), configured to impart a drive torque to the first movement wheel (121 ) or to the second movement wheel (131 ), to move the cleaning device (1 ) on the solar panel (P) along a longitudinal direction (L) perpendicular to the transverse direction (T);- a control unit, configured to command the actuating unit to instruct it to move the cleaning device (1) along the longitudinal direction (L);- a cleaning system, comprising:- a scrubbing unit (14), interposed between the first and the second movement wheel (121 , 131 ) along the transverse direction (T), for contacting a working surface of the solar panel (P);- a dispenser (15), connectable to a fluid supply tank (RS) and configured to deliver a cleaning fluid to the working surface (P1 ) of the solar panel (P), characterized in that the first and the second movement wheel (121. 131 ) are configured to move the cleaning device (1 ) by means of the rolling friction that is generated between the first or the second movement wheel (121 , 131 ) and a corresponding rolling surface.

2. The device according to claim 1 , comprising a guide system, including a plurality of rolling elements, rotating about respective axes perpendicular to the longitudinal direction (L) and configured to remain in contact with the solar panel (P) as the cleaning device (1 ) moves along the longitudinal direction (L).

3. The device (1 ) according to claim 2, wherein the guide systemcomprises a group of transverse rolling elements (124, 134), configured to rotate about an axis parallel to the transverse direction (T), and wherein the group of transverse rolling elements (124, 134) is aligned with the respective first or second movement wheel (121 , 131 ) along the longitudinal direction.

4. The device (1 ) according to claim 2 or 3, wherein the guide system comprises a group of longitudinal rolling elements (125, 135), configured to rotate about an axis perpendicular to the transverse direction (T), and wherein the rolling elements of the group of longitudinal rolling elements (125, 135) are larger in diameter than the rolling elements of the group of transverse rolling elements (124, 134).

5. The device (1 ) according to claim 3 or 4, wherein the rolling elements of the group of longitudinal rolling elements (125, 135) are adjustable in position along the transverse direction (T).

6. The device (1) according to any one of the preceding claims, wherein the scrubbing unit (14) comprises a cleaning rod (141 , 142), which rotates relative to the mounting frame (11 ), and a scrubbing element (145, 146), mounted to the cleaning rod (141 , 142) to rotate on the working surface (P1 ) of the solar panel (P).

7. The device (1 ) according to claim 6, wherein the actuating unit comprises a scrubbing actuator (143, 144), configured to rotate the cleaning rod (141 , 142) of the scrubbing unit (14).

8. The device (1) according to any one of the preceding claims, wherein the dispenser (15) comprises a duct (151 ), elongated along the transverse direction (T) and including a plurality of nozzles (152), distributed along the transverse direction (T) and oriented in such a way as to direct the cleaning fluid at the working surface (P1 ) of the solar panel (P).

9. The device (1) according to any one of the preceding claims, wherein the movement actuator comprises a first motor (123), configured to actuate the first movement wheel (121 ), and a second motor (133), configured to actuate the second movement wheel (131 ).

10. The device (1) according to any one of the preceding claims, comprising a detection unit including one or more of the following sensors:- a torque sensor, configured to detect a torque signal, representing a torque delivered by the movement actuator (123, 133);- an optical sensor, configured to detect the presence of one or more obstacles on the solar panel (P);- one or more inspection cameras, configured to capture image data representing a state of cleanliness of the working surface (P1 ) of the solar panel (P);- a level sensor, configured to detect the level of fluid inside a tank (RS) of the device (1 ).

11. The device (1 ) according to claim 10, wherein the control unit is configured for:- receiving the torque signal from the torque sensor;- comparing the torque value derived from the torque signal with a preset threshold value;- inverting the feed direction of the device (1) responsive to the detected torque value exceeding the preset threshold value.

12. The device (1 ) according to claim 10, wherein the control unit is configured for:- receiving the image data from the one or more cameras;- processing the image data to derive information regarding the state of cleanliness of the solar panel;- based on the information regarding the state of cleanliness of the solar panel, deriving a value of a control parameter;- comparing the value of the control parameter with a preset threshold value;- starting the device to run a cleaning cycle if the derived control parameter value exceeds the preset threshold value.

13. The device according to any one of the preceding claims, comprising a pair of rails (41 , 42) disposed at a first transverse end (P2) of the solarpanel (P) and at a second transverse end (P3) of the solar panel (P) respectively, and wherein each rail comprises an L profile or a U profile.

14. A cleaning unit (100) for cleaning a solar panel (P), comprising:- a cleaning device (1 ) according to any one of the preceding claims;- a fluid supply tank (RS), connected to the dispenser (15) of the device to supply the latter with a flow of cleaning fluid.

15. The cleaning unit (100) according to claim 14, comprising a parking platform (2), configured to be connected to a longitudinal end of the solar panel (P) at a position outside of the working surface (P1 ) of the solar panel (P), wherein, between one cleaning cycle and the next, the cleaning device (1) is configured to be positioned on the parking platform (2).

16. The cleaning unit (100) according to claim 14 or 15, comprising a hose (101 A) and a reel (101 C) on which the hose (101 A) is rolled, the hose (101 A) connecting the fluid supply tank (101 B) to the dispenser (15).

17. A unit for generating electrical power from solar energy, comprising:- a solar panel (P), including a working surface (P1) for receiving solar radiation and converting the solar energy into electrical energy;- a cleaning device (1 ) according to any one of claims 1 to 13.

18. A method for cleaning a solar panel (P), comprising:- providing a cleaning device (1 ), comprising: a mounting frame (11), elongated along a transverse direction (T) between a first end and a second end; a first movement wheel (121 ), connected to the first end of the frame (11 ), and a second movement wheel (131 ), connected to the second end of the frame (11 );- positioning the device (1 ) on the solar panel (P), with the first movement wheel (121) in contact with a respective rolling surface, located at the first transverse end (P2, 41) of the solar panel (P) and with the second movement wheel (131 ) in contact with a respective rolling surface, located at the second transverse end (P3, 42) of the solar panel (P);- actuating the first movement wheel or the second movement wheel (121 ,131 ) via a movement actuator (123, 133) which imparts a drive torque to the first or the second movement wheel (121 , 131 ));- moving the cleaning device (1 ) on the solar panel (P) along a longitudinal direction (L), perpendicular to the transverse direction (T); - via a control unit, commanding the actuating unit to impart instructions to it during the step of moving the cleaning device;- scrubbing dirt from a working surface (P1 ) of the solar panel (P) via a scrubbing unit (14), interposed between the first and the second movement wheel (121 , 131 ) along the transverse direction (T);- delivering a cleaning fluid to the working surface (P1 ) of the solar panel (P) via a dispenser (15) which is connectable to a fluid supply tank (101 B, RS).

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