Cleaning apparatus for a solar power plant

Abstract

A cleaning apparatus for solar panels comprising: a mounting structure (114) configured for mounting the apparatus on a mobile unit (16); a support arm (130) moveably connected to the mounting structure, a first drive mechanism (128) being operably connected to said support arm for moving the latter relative to said mounting structure in the vertical direction (Z); a cleaning device (100) mounted to the support arm, comprising: a suspension arm (130) extending from a first end portion (132), pivotally connected to said support arm to a free second end portion (134), along a first axis (A), and associated second drive mechanism (138) for actuating said suspension arm; a cleaning head (160) with a cleaning tool (166) having a main extension along a second axis (B), two actuators (144, 144') configured to move the cleaning head relative to the suspension arm, the actuators connected to the cleaning tool at axially opposite fixing points, each actuator being selectively actuatable such that the ends of the cleaning head can move vertically independently from one another, whereby the angular position of the cleaning tool can be selectively adjusted separately from the suspension arm.

Description

[0001] Cleaning apparatus for a solar power plant

[0002] Technical field

[0003] The present invention relates in general the field of cleaning solar devices, and in particular to a cleaning apparatus for cleaning solar panels or solar collectors.

[0004] Background Art

[0005] The solar industry is developing rapidly as the sun is an infinite source of renewable energy and so provides a solution for reducing emissions. Solar devices are very widely present, for example arranged on support structures in fields, on roofs or on coverings for protecting cars in car parks from the sun, etc. A distinction is generally drawn between photovoltaic solar panels and thermal solar collectors.

[0006] A photovoltaic solar panel (also known as a photovoltaic module) generates electrical energy by converting sunlight. The photovoltaic module is composed of solar cells which are electrically interconnected.

[0007] Thermal solar collectors are devices designed to collect solar energy transmitted by radiation and transfer it to a heat transfer fluid (gas or liquid) in the form of heat. Also taking the form of panels, they are frequently mounted on roofs and used to produce domestic hot water or heating.

[0008] Both solar devices of the thermal sort and those inherent to the photovoltaic technology are generally composed of a plurality of modules having a substantially flat form, each having an active surface for receiving the solar radiation in order to transform it into heat or electrical energy.

[0009] Accumulated dirt, dust, and debris can significantly reduce the efficiency and overall energy output of the solar devices, so that it is important to keep the active surface clean by performing periodical cleaning thereof, thereby ensuring the solar devices remain efficient.

[0010] For rooftop solar panels or collectors, cleaning can be done manually (e.g. by an operator with broom and waterjet on the roof). When the slope of the roof and / or the area of the solar devices increases, it is possible to use an articulated arm with a brush (if the roof is not too high) or remote-controlled tracked robots (see for example WO 2020 / 200694 A1 ) which move over the panels.

[0011] In the case of industrial installations such as e.g. power plants or solar farms, which comprise large arrays of panels or collectors arranged on ground-mounted structures, cleaning may be carried out by brush devices which move over the rows of solar panels, guided by rails placed on the devices and / or their edges. Such devices are known for example from DE 10 2010 025 845 A1 .

[0012] It is also possible to make use of vehicles travelling on the ground between the rows of solar panels, the vehicles being equipped with cleaning devices. For example, EP 2 567 758 describes a cleaning assembly comprising a brush fixed to a hydraulically operated articulated arm which is configured for being mounted on a tractor. US 2020 / 164414 A1 also describes a cleaning assembly comprising a brush fixed to a hydraulically operated articulated arm mounted on a vehicle.

[0013] However, such cleaning assemblies lack precise control over the movement of the brush. The hydraulically operated articulated arms, while powerful, often struggle with maintaining the stability and exact positioning required for effective and safe cleaning. As a result, the brush may sway or balance uncontrollably during cleaning. This uncontrolled movement can lead to the brush coming into uneven or excessive contact with the surface of the solar devices, potentially causing scratches, abrasions, or other forms of damage.

[0014] The unintended damage caused by these traditional cleaning methods not only necessitates costly repairs or replacements but can also reduce the efficiency and lifespan of the solar devices.

[0015] Therefore, there is still a need for an improved cleaning device that can provide a controlled and stable cleaning action, ensuring both the cleanliness and the integrity of the solar devices. Object of the Invention

[0016] The object of the invention is to provide a solar panel cleaning apparatus with an improved design which enables effective control of movements of the cleaning tool and prevent it from swaying.

[0017] General Description of the Invention

[0018] The present invention relates a cleaning apparatus for solar panels as claimed in claim 1. The cleaning apparatus comprises: a mounting structure configured for mounting the apparatus on a mobile unit; a support arm moveably connected to the mounting structure, a first drive mechanism being operably connected to said support arm for moving the latter relative to said mounting structure in the vertical direction; a cleaning device mounted to the support arm, comprising: a suspension arm extending from a first end portion, pivotally connected to said support arm to a free second end portion, along a first axis A, an associated second drive mechanism for actuating said suspension arm; a cleaning head with a cleaning tool having a main extension along a second axis B, two actuators configured to move the cleaning head relative to the suspension arm, the actuators comprising connected to the cleaning head at axially opposite fixing points, each actuator being selective actuatable such that the ends of the cleaning head can move vertically independently from one another, whereby the cleaning head can be selectively adjusted relative to the surface to be cleaned separately from the suspension arm.

[0019] The invention hence provides a cleaning apparatus that provides two angular adjustment capacities: a first angular adjustment is achieved by means of the drive mechanisms, that allow generally positioning the cleaning device relative to the surface to be cleaned (top surface of the solar panels). This can be seen as a coarse positioning, where the goal is to have the first axis globally parallel to the solar panels.

[0020] - a second angular adjustment is achieved by means of the actuators, that permit positioning of the cleaning head relative to the suspension arm. This provides a fine positioning function. Indeed, whereas the suspension arm is positioned with axis A, it is possible to finely adjust the position of the cleaning head, both in terms of inclination and distance relative to the solar panels.

[0021] It may be appreciated that the actuators, directly connected to the cleaning head, allow fast and precise actuation, and hence efficient real time adjustment of the position of the cleaning head. The actuators only bear the weight of the cleaning head. This is clearly swifter and more accurate than actuation through drive mechanisms located remotely in the kinematic chain.

[0022] Altogether this improved control allowed by the cleaning apparatus provides for a safer operation of the device, in particular avoiding shocks of the cleaning unit against the solar panels.

[0023] In embodiments, the apparatus may comprise a guiding structure configured to accompany the cleaning head displacement along the vertical direction while limiting movements of the cleaning head perpendicularly to the vertical axis.

[0024] The guiding structure assists the movements of the cleaning head and limits swaying, i.e. undesired moves in the cleaning direction and transversal to the cleaning direction. This guiding structure is of particular interest when using actuators comprising flexible links / cords. Stated otherwise, the wherein the guiding structure is preferably configured to maintain the cleaning head in a substantially constant orientation during its vertical displacement, relative to the suspension arm.

[0025] As used herein, “limiting” movements or swaying is understood as preventing or avoiding such movements under normal operation, such that the guiding structure is configured to substantially inhibit lateral and transverse displacements of the cleaning head, and any residual excursions are reduced to a negligible amplitude that poses no risk of contact, shock, or damage to the solar panels. Preferably, the guiding structure is configured to prevent movement of the cleaning head in directions transverse to the vertical axis and / or preventing rotation about axes orthogonal to the vertical axis.

[0026] In combination, these constructional measures provide for an efficient control of the position of the cleaning head and accordingly an improved operational safety, in that cleaning head swaying can be limited - hence avoiding shocks / damages to the solar panels.

[0027] In embodiments, the guiding structure comprises pivoting levers connected together, to form a mechanical linkage that allows vertical movement of the cleaning head relative to the suspension arm, with limited movement in the direction of axis B or transversal thereto. Preferably, the pivoting levers may be configured to form a scissor-type linkage structure. Such guiding structure advantageously allows precise control of the cleaning head's vertical position and movement while restricting unwanted lateral or transverse movements. The scissor-type linkage ensures stable movement, reducing the risk of sway, which is particularly beneficial for cleaning large and fragile surfaces such as solar panels. Other appropriate configuration of guiding structure may be employed, in particular foldable structures based on parallelogram or pantograph-type geometry, providing substantially rectilinear motion of the cleaning head within a vertical plane.

[0028] In general, the guiding structure is designed to constrain the cleaning head so that, during vertical movement, its motion remains within a defined vertical plane — i.e. it prevents lateral deviations out of that plane; but also avoids deviating from a predefined stroke movement within the plane.

[0029] The guiding structure thus acts as a planar guiding or stabilising mechanism, not as the main lifting means.

[0030] Additionally or alternatively, the guiding structure may further comprise a first reinforcing member arranged to couple one end portion of the suspension arm with a corresponding end portion of the cleaning head, and a second reinforcing member arrange to couple the other (opposed) end portion of the suspension arm with a corresponding portion of the cleaning head. These reinforcing members (further) increase the mechanical stability of the cleaning unit, reducing any flex or instability (such as e.g. lateral or transverse movement) that could impair cleaning precision.

[0031] Preferably, the second reinforcing member includes a pair of V-shaped levers, with one lever pivotably connected to the guiding arm and the other to the cleaning head. V-shaped levers further prevents I minimizes lateral movements. In other words, the V-shaped lever arrangement adds further structural rigidity and enhances the ability to maintain the position (in a plane parallel to the surface to be cleaned / ground) of the cleaning head during operation.

[0032] In embodiments, the first reinforcing member includes a main lever pivotally connected at one end to the cleaning head and engaged at the other end in a guide rail of the suspension arm. A complementary lever is pivotally connected to both the main lever and the suspension arm. This dual-lever mechanism ensures smoother, more controlled movement of the cleaning head. The use of guide rails further stabilizes the system, preventing any unexpected shifts in position during cleaning operations, thereby improving precision and operational safety.

[0033] In embodiments, the guiding structure comprises a Y-shaped lever mechanism linked one end of the cleaning head to the suspension arm, whereas a V-shaped lever is arranged at the other end.

[0034] In embodiments, the actuators of the cleaning apparatus comprise a flexible link, by which the cleaning unit is supported by (from) the suspension arm. The length of the flexible link below the suspension arm is adjustable. The adjustable flexible link enables a fine-tuned control of the height of the cleaning head, accommodating variations in panel height or terrain.

[0035] Preferably, the flexible link is wound on a spool coupled to a motor, to wind or unwind therefrom a length of the flexible link, thereby adjusting the length of the link.

[0036] In alternative embodiments using flexible links, the guiding structure may comprise one or more vertical guides, e.g. a rigid rod along which the cleaning unit is guided (sliding connection) in the vertical plane. Still in other embodiments, the actuators for the cleaning head may be rigid actuators, like jacks or the like.

[0037] In embodiments, the first and second drive mechanisms comprise (each) a linear actuator. Linear actuators provide smooth, consistent motion thereby enhancing the precision of movement, ensuring that the cleaning head remains stable and correctly positioned.

[0038] It may be noted that the drive mechanisms, actuators and motors (and in general actuating / driving components) used in the cleaning device can be configured for operation with hydraulic or electrical energy sources, or even pneumatic. For instance, the first / second drive mechanisms and / or the actuators for the cleaning head may include electric motors or electromechanical actuating devices supplied by rechargeable batteries, which provide the necessary electrical power for their operation. Alternatively, the first / second drive mechanisms and / or the actuators for the cleaning head can be configured to be actuated through pressurized hydraulic fluid. This flexibility in power sources allows for versatile and adaptable operation, enabling the cleaning device to perform efficiently in a range of applications and environments.

[0039] According to the same or other embodiments, the mounting structure of the cleaning apparatus comprises a tower, and the support arm is pivotally connected to the tower. The angular position of the support arm is preferably controlled by the first actuating means I first drive mechanism.

[0040] In embodiments, the solar device cleaning apparatus may comprise at least one distance sensor arranged to determine a distance between the cleaning head, preferably the cleaning tool, and a respective surface to be cleaned (e.g. a solar panel), and a control unit connected to the at least one distance sensor. The control unit is configured to adjust the position of the cleaning head, preferably of the cleaning tool, with respect to the surface to be cleaned by actuating at least parts of the drive mechanisms and actuators.

[0041] In other words, the cleaning apparatus according to the invention preferably comprises at least one distance sensor which is arranged to determine the distance between the cleaning tool (e.g. brush) and the surface of the panels to be cleaned. According to preferred embodiments, the cleaning apparatus comprises two, four or six distance sensors, enabling more precise determination of the position of the cleaning tool and its orientation with respect to the surface of the solar panels. The distance sensors are preferably mounted on the frame, which acts as a support structure moving integrally with the cleaning tool under the action of the actuating means, therefore close to the cleaning tool itself. The distance sensors typically measure the distance in the substantially vertical direction, therefore essentially at right angles to the position of the cleaning tool.

[0042] The orientation of the cleaning tool may be controlled by two distance sensors placed at each end of the cleaning head, respectively the frame or cleaning tool, in order to detect the edge regions of the solar panel or row of panels.

[0043] Preferably, the sensors are arranged in pairs, one sensor being positioned on the front of the cleaning head and one sensor being on the back (relative to the direction of movement). The front of the cleaning head corresponds to the side of the head facing the dirty surface to be cleaned and the back of the cleaning head corresponds to the side of the head facing the cleaned surface. The cleaning apparatus can thus be moved in two directions. The sensors also make it possible to detect the end of a panel I row of panels or a space between the panels in a row.

[0044] Advantageously, a pair of sensors is arranged at each end of the cleaning head. Depending on the type of solar installation to be cleaned, for example in the case of cleaning solar trackers supporting conventional solar panels, it is also advantageous to equip the cleaning head with a third pair of sensors arranged in the middle of the head along its length, which make it possible to detect any excess thickness located in the middle (in the direction of the length of the frame) of the tracker and so to lift the cleaning head at that point.

[0045] The solar devices (e.g. solar panels) arranged in rows are not necessarily in contact with one another, such that a free space may be formed, in a second direction, between two adjacent devices in the same row. The control unit is advantageously configured to evaluate the sensor signal such that this space is recognised as such and the cleaning head is not lowered. Any known type of distance sensor may be used as the distance sensor according to the invention, in particular sensors of - but not being limited to - the LIDAR type of the (depth) video camera type. When the cleaning apparatus comprises more than one distance sensor, the various sensors may be identical or different from one another.

[0046] In embodiments, the cleaning head further comprises driving means for driving, preferably rotating, the cleaning tool (typically brush). Such integrated driving means may allow for automatic operation of the cleaning tool, making the system more efficient. By using rotational motion, the cleaning process is more effective, particularly for removing dust and debris that can accumulate on solar panels.

[0047] The cleaning tool is advantageously of the brush type and may have one or more brushes configured to extend across the length of the frame along the first axis. The cleaning tool preferably comprises at least one rotary brush extending across the length of the frame along first axis (A).

[0048] In embodiments, the rotary brush is a cylindrical brush having a central shaft parallel to, or concentric with, the first axis, and is driven in rotation about the central shaft. The cylindrical brush has a predetermined length appropriate to the width of the panel or row of panels to be cleaned. The cylindrical brush may be composed of one or a plurality of sections. When the brush has a plurality of brush sections, the brush bristles are preferably arranged to cover junction zones between two adjacent brush sections.

[0049] In embodiments, the cleaning tool may comprise a second cylindrical rotary brush, the central shaft of which is parallel to the first axis and offset from the latter, said other brush being driven in rotation about its central shaft. The two cleaning brushes are thus arranged side by side, i.e. one behind the other in the cleaning direction.

[0050] Other brush cleaning tool configurations may be considered. For example, according to embodiments, a plurality of axial rotary brushes may be fixed to a supporting cross-piece extending across the length of the frame. The radial brushes are arranged side by side so as to cover the length of the frame along first axis. Each axial rotary brush has an axis of rotation which extends substantially perpendicular to the supporting cross-piece and therefore, when in use, to the surface of the solar panels to be cleaned.

[0051] The brushes have bristles / fibres made from any material appropriate for cleaning solar panels, for example from nylon, microfibres or foam.

[0052] Preferably, the herein disclosed cleaning apparatus relates to cleaning planar solar panels, such that the brush has zero curvature between its two ends. The cleaning apparatus according to the invention may, however, readily be adapted to clean all types of solar devices, for example cylindrical parabolic thermal solar collectors, and in this case the brush has between its ends an external profile corresponding to the curvature of the solar collector to be cleaned, so as to ensure brush contact over the entire surface to be cleaned and consequently uniform cleaning of the solar collector.

[0053] In other embodiments, the cleaning tool may comprise any other configuration of brushes, squeegees and / or sweeps extending across the length of the frame which are appropriate for cleaning the surface of the solar devices such as solar panels.

[0054] In embodiments, the cleaning apparatus further comprises a washing liquid tank and means for spraying washing liquid, for example water. These spraying means may comprise jets or nozzles fixed to the cleaning head, such as e.g. to the frame or directly on the cleaning tool in order to spray jets of washing liquid towards the solar panels. In this case, the cleaning apparatus comprises one or more tanks for washing liquid, spray nozzles and a distribution circuit with pump connecting the tanks to the nozzles.

[0055] In embodiments, the cleaning apparatus further comprises a counterweight configured for balancing the weight of the support arm, cleaning device, and preferably also guiding structure. The counterweight ensures that the apparatus remains balanced and stable during operation. This reduces strain on the actuators and minimizes the risk of tipping or imbalanced motion, thus improving the overall durability and performance of the system, and also precision of the movement of the cleaning head. Although the present cleaning apparatus was developed for cleaning solar devices having a planar surface exposed to the sun, it can be applied to all types of solar devices, whether photovoltaic panels or thermal collectors, flat or dished, subject if needs be to any adjustments to dimensions and / or shape of the cleaning head.

[0056] In a second aspect, the present invention also relates to a mobile unit comprises the cleaning apparatus for solar panels according to the first aspect. Preferably, the mobile unit comprises a chassis supporting the cleaning apparatus and wheels, and more preferably an engine or motor for self-propelling.

[0057] The cleaning apparatus may be mounted to various kind of mobile unit, so as to be used in a wide variety of environments, from large, flat solar farms to remote, difficult to access installations.

[0058] In embodiments, the mobile unit is selected from an automobile vehicle, such as a flatbed truck or pickup truck, a tractor, a construction truck, or an autonomous mobile robot, an AGV, or a trailer.

[0059] Preferably, the cleaning apparatus is fixed via its mounting structure onto the truck flatbed or load area of the pickup truck. Alternatively, in some equally preferred embodiments, the mobile unit may be a tractor, and the mounting structure comprises a coupling interface configured to cooperate with a tractor hitch.

[0060] Mounting the cleaning apparatus on a truck flatbed, load area of a pickup truck or tractor allows for efficient transport and operation across large installations, reducing setup time and improving the ease of deployment. It is also easier and cheaper to equip an existing vehicle with the inventive cleaning apparatus than developing / buying a dedicated mobile unit. This is particularly the case in solar farms which already own a fleet of pickup trucks and tractors.

[0061] Brief Description of the Drawings

[0062] Preferred embodiment of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:

[0063] Fig. 1 is a top view of a cleaning apparatus according the invention; Fig. 2 is a perspective view of the cleaning device of the cleaning apparatus of Fig. 1 ;

[0064] Fig. 3 is a side view of the cleaning device of the cleaning apparatus of Fig. 1 ;

[0065] Fig. 4 is a detail side view of the cleaning head and suspension arm of the apparatus of Fig. 1 , in a rest configuration;

[0066] Fig. 5 and 6 show an embodiment of the present cleaning apparatus mounted on a pickup truck, in operation on two different solar panel configurations.

[0067] Description of Preferred Embodiments

[0068] An embodiment of the present invention will be described herein below in the context of solar farms, where the apparatus is used for cleaning planar solar panels, such as rows of photovoltaic panels with planar surfaces exposed to the sun.

[0069] Figs. 1 to 3 show a top view, perspective view and side view of an embodiment of the present cleaning apparatus 10 for solar devices. Here, the cleaning apparatus 10 is configured for mounting on a pick-up truck 16, which is only shown in Fig.1 . The cleaning apparatus 10 is fixed on the load carrying area 16.1. of the pickup 16. This forms a self-propelled mobile unit for cleaning solar panels / devices.

[0070] In a solar farm, solar panels 12 are generally arranged in parallel rows 14 of multiple panels mounted on metal frames anchored to the ground. These panels are usually oriented toward the sun to maximize energy absorption. In the northern hemisphere, they are often tilted and face south, while in the southern hemisphere, they face north. The angle of tilt is optimized based on the latitude of the location to capture the most sunlight throughout the day. In some solar farms, the panels may also be mounted on trackers, which allow them to move and follow the sun's path for improved efficiency.

[0071] In fig.1 , with reference to the Cartesian coordinate system shown on the drawing for ease of explanation, the solar panels 12 are aligned to form rows 14 in the X direction and the cleaning apparatus moves in this X direction when cleaning the solar panels 12.

[0072] The apparatus 10 generally comprises:

[0073] - a mounting structure 110 configured for mounting the apparatus on a mobile unit (here the pickup 16);

[0074] - a support arm 130 moveably connected to the mounting structure 114 and configured to control the elevation along the vertical direction Z;

[0075] - a cleaning device 100 mounted to the support arm, which includes:

[0076] - a suspension arm 142 mounted to the support arm 130, extending along a first axis A;

[0077] - a cleaning head 160 with a cleaning tool 166 (here a cylindrical brush) having a main extension along a second axis B. The cleaning tool 166 may typically be supported by a frame 162. The cleaning head 160 is arranged below the suspension arm 142 and is supported by the latter. Two actuators are configured to move the cleaning head 160 relative to the suspension arm 142. The cleaning head 160 can thus be said to be suspended to the suspension arm;

[0078] - a guide structure configured to accompany the displacements of the cleaning head 160 along the vertical direction, while limiting movement of the cleaning head 160 perpendicular to the vertical axis.

[0079] The mounting structure 110 comprises a base plate 112 with an associated fixing frame 114. The fixing frame 114 here presents a generally T-shaped frame, having transverse segments (or members) 114.1 , 114.2, 114.3 and longitudinal crossbars 114.4, 114.5 (or members). The transverse segments 114.2 and 114.3 are connected via crossbars 114.5. Holes 116 are provided through at least part of the frame members to allow for a (detachable) mounting onto a surface of a mobile unit, here the load charging area 16.1 (flatbed) of the pickup truck 16, e.g. by rivets, bolts or screws. The base plate 112 is fixed to the fixing frame 114. This is only an example of mounting structure 110; other configurations can be devised by the skilled person, the purpose being to firmly and stably fix the apparatus 10 to the mobile unit. In alternative embodiments, the mounting structure 110 may be mounted on an Automated Guided Vehicle (AGV) (not shown).

[0080] The base plate 112 supports a tower 120 (or mast) - forming a support base - which extends upwardly along the direction of axis Z from a tower first end 122 connected to the base plate 112, to a tower second end 124. In particular embodiments, the tower first end 122 can be fixedly attached in relation to the mounting base plate 112. It is however possible that the tower 120 be rotatably mounted (pivoting about axis Z) to the base plate 112, while preferably being fixed in the X and Y direction (with respect to the base plate).

[0081] The support arm 130 extends from a first end portion 132 connected to the (upper) second end 124 of the tower 120, to a second end portion 134. The support arm 130 may typically be straight, although other shapes may be possible. Connection between the support arm first end portion 132 and the tower second end 124 may occur through a pivot liaison.

[0082] Preferably, the tower second end 124 supports a first pivot 131 which defines a rotation axis about which the support arm 130 rotates to control the elevation (vertical direction) of the cleaning head 160, in particular relative to the row of solar panels 12 to be cleaned. As depicted, the tower second end 124 may present a pair of pivot bearing surfaces 126 disposed in spaced apart relation which bear the support arm pivot 131.

[0083] The support arm pivot 131 may be arranged at a distance from the first end portion 132; it is however preferred that it be arranged proximal to the first end portion 132.

[0084] The support arm 130 is coupled to a drive mechanism 128 operable to rotate the support arm 130 about the support arm pivot 131. As shown in the Figures, the drive mechanism 128 can, for the sake of exemplification, be a linear actuator having an actuating member 128.2 coupled to the support arm 130 and having a base 128.1 coupled to the tower 120 or base plate 112. The linear actuator may be an electric, hydraulic or pneumatic jack, where the actuating member 128.2 is a piston-rod that is reciprocally moveable relative to the base 128.1 forming a cylindrical housing.

[0085] In operation, the actuation of the drive mechanism 128 allows varying, depending on the position (extent) of the actuating member 128.2, the angular position of the support arm 130 and hence vary the altitude of the second end portion 134 of the support arm 130.

[0086] While the tower 120 and support arm 130 disclosed in the figures are depicted each as one massive (hollow or full) profile of rectangular cross-section, it is still within the scope of the present disclosure that the tower and / or support arm be made from a plurality of profiles, tubes (of rectangular or other cross-section) and / or beams, assembled by any appropriate means, in particular rigidly, for example by welding, screwing and / or riveting, with perpendicular or oblique cross-pieces connecting two parallel tubes for reinforcement.

[0087] As apparent from above, the XYZ coordinate system is defined relative to the apparatus 10 and therefore comprises three axes perpendicular to each other, namely the horizontal X axis, parallel to the ground and corresponding to the general direction of movement of the apparatus 10 along the row 14 of solar panels 12; the horizontal transverse Y axis, likewise parallel to the ground and perpendicular to the X axis; and the vertical Z axis, perpendicular to the ground and to the horizontal X, Y plane.

[0088] In general, the dimensions of the device, in particular its height HA in the Z direction and the length L of the cleaning head in the Y direction (along axis A), are defined depending on the characteristics of the solar panels 12 to be cleaned.

[0089] The tower 120 and support arm 130 are preferably made as independent (preassembled) elements and these main elements are then assembled. Connection can be made by any appropriate means, for example welding, screwing, riveting, etc. The use of removable fasteners such as bolts or screws facilitates disassembly. Ease of disassembly is of particular interest in some variants, not shown here, where towers and / or support arms of different lengths are available. This makes it possible to adapt the dimensions of the cleaning device 100 of the cleaning apparatus 10 to the width and height of the solar panels 12 to be cleaned. Another alternative (not shown) involves using a telescopic tower and / or support arm with telescopic tubes.

[0090] The suspension arm 142 is pivotally connected (via pivot liaison 141 ) to the second end portion of the support arm 130 and supports the cleaning head 160.

[0091] The suspension arm 142 extends along an axis A from a first end portion 142.1 , connected to the support arm 130, to an axially opposite second end portion 142.2 (free end). The articulation of the suspension arm 142 on the support arm 130 permits controlling the angle of the suspension arm 142, in particular relative to the solar panels to be cleaned. As depicted, the suspension arm first end 142.1 may include an actuating portion extending transversally from axis A, here upwardly (i.e. on the upper side of the suspension). In particular, the actuating portion may comprise a pair of first vertical flanges 143 (hence extending transversally to axis A) disposed in facing one another on the lateral sides of the suspension beam. These support a pivot 141 that provides the articulation with the support arm 130.

[0092] A second drive mechanism 138 is operably connected to the suspension arm 142, in particular its flanges 143, to selectively rotate the suspension arm 142 about pivot 141. Specifically, the second drive mechanism 138 is connected to the flanges 143 in a region offset from the pivot 141. The second drive mechanism 138 may be of the same type as the first drive mechanism 128, namely with an actuating member 138.2 and base 138.1.

[0093] The support arm 130 may present a pair of vertical second flanges 136 fixed in facing relationship on the support arm 130 and which bear both the first end 128.2 of the linear actuator 128 and the second end 138.1 of the linear actuator 138.

[0094] The pairs of flanges 143, 136 may be fixed to the support arm, respectively suspension arm, by any means known in the art, such as e.g. welding, riveting, screwing. The position of the cleaning head 160 relative to the solar panels to be cleaned is adjusted by means of actuators 144, 144’ arranged on the suspension arm 142. In particular, the actuators 144, 144’ are spaced from one another, typically arranged at or near the extremities 142.1 , 142.2 of the suspension arm 142 and connecting the cleaning head 160 likewise at two axially spaced fixing points. Typically, each fixing point is located in a respective half of the cleaning head 160. Preferably the fixing points are symmetrically arranged relative to the centre of the cleaning head. Here, the fixing points are realized as fixing brackets 163, 165 with a central portion and two branches fixed to the cleaning head. The fixing brackets 163, 165 may have a U or C shaped profile, or a semi-circular profile, or any adapted profile.

[0095] In this embodiment, the actuators 144, 144’ comprise a flexible link such as e.g. a cord or belt 145 that is attached at one end to a respective fixing bracket 163, 165, and wound on a spool 147 at the opposite end. The spool is rotationally coupled to an motor 149 (in particular electric motor), which allows controlling the unwound length of the belt.

[0096] As will be understood, by rotating the spool 147, the belt 145 is either unwound from the spool, thereby increasing the belt’s length and the distance between the cleaning head 160 and the suspension arm 142, or wound thereon, thereby reducing said distance.

[0097] In a rest state of the cleaning apparatus 10 (i.e. when the apparatus is not in use or during transport), the belt 145 is wound around the spool so that the cleaning head 160 is close to the suspension arm 142. This is the case in the configuration of figures 3 and 4, accordingly only a small length of belt 145 is visible.

[0098] In use, i.e. during cleaning, the belt is at least partially unwound from the spool so as to move the cleaning head 160 toward the solar panels along the Z- direction. This is best seen in Figs 5 and 6.

[0099] While it is preferred, for ease of manufacturing and assembly, that both actuators 144, 144’ be of the same type and of similar construction, it is to be understood that they are designed be operated independently from each other, so as to allow the cleaning head 160, in particular the cleaning tool 166, to be tilted with respect to the axis A of the suspension arm 142.

[0100] It may be particularly noted that the inclination of the cleaning tool 166 (i.e. of axis B) is typically controlled to corresponds to orientation of the surface of the solar panels to be cleaned.

[0101] In this connexion, it should be appreciated that in use, the suspension arm 142 provides for coarse adjustment of the angular cleaning position. That is, the suspension arm 142 does not need precise adjustment. A more precise positioning of the cleaning head 160 relative to the solar panels is achieved by means of the actuators 144, 144’, which allow finely adjusting the position I distance of the cleaning unit relative to the solar panels, namely to ensure that axis B is parallel to the surface to be cleaned, at a controlled distance.

[0102] The vertical movements of the cleaning head 160 are assisted by the guiding structure 150, which here comprises reinforcing members 152, 154 connecting the suspension arm to the cleaning head. For improved stability, the reinforcing members 152, 154 are arranged on both lateral sides.

[0103] The first reinforcing members 152 are arranged near the first end 142.1 of the suspension arm 142 and linked to the cleaning head 160, in particular to the first bracket 163 mounted to the frame 162, near its first end.

[0104] The first reinforcing member 152 is designed as Y-shaped lever and comprises a main lever 152.1 , one end 152.2 of which is articulated on the first bracket 163 whereas the opposite end 152.3 is slideably engaged in a guide rail 153 on the suspension arm 142. The guide rail 153 may extend along the direction of axis A. The guide rail 153 may be formed integrally with the suspension arm 142 (e.g. formed as a slit-shaped recess) or be a separate guide rail 153 attached by any appropriate means to the suspension arm 142. The complementary lever 152.4 of the first reinforcing member 152 is pivotally attached at one end 152.5 to the main lever 152.1 , toward its centre, and at the other end 152.6 to the suspension arm 142. The Y-shaped lever design thus allows vertical movement of the cleaning head 160 while limiting swaying thereof along axis B.

[0105] As depicted, the second reinforcing member 154 is arranged near the second end portion 142.2 of the suspension arm 142 and connects the second bracket 165 of the cleaning head.

[0106] The second reinforcing member 154 comprises two levers 154.1 , 154.2 configured as V-shaped mechanical linkage. Lever 154.1 is pivotally connected at one end to the suspension arm and at the other end to an extremity of lever 154.2, which is pivotally connected to the second bracket 165 of the cleaning head 160.

[0107] It is to be understood that the position of the reinforcing members 152, 154 may be adapted, in particular the first reinforcing member 152 may be distal to the support arm 130 and the second reinforcing members 154 may be proximal to the support arm 130; or on one side the first reinforcing members 152 may be proximal to the support arm 130 while they are distal to the support arm 130 on the second, opposite side of the suspension 142.

[0108] The cleaning apparatus 10 may further advantageously comprise a counterweight 180 to balance weight of the support arm 130, guiding structure 150 and cleaning head 160. It may be advantageously designed ensure the center of gravity aligns in a way that enhances stability, efficiency and / or control. The counterweight 180 may be of any kind known in the art and dimensioned depending on the characteristics (size, weight... ) of both the support arm 130 and the cleaning head 160. In embodiments, the counterweight 180 may present as a massive block 182 attached at one extremity of a counterweight arm 184, the second end thereof attached to the top of tower 120, e.g. to its pivot bearing surfaces 126.

[0109] The cleaning head 160 advantageously comprises the frame 162 that pivotally supports the cleaning tool 166 in rotation about its axis B. In the present embodiment, the cleaning tool 166 is a cylindrical brush that comprises a central shaft (parallel to or coaxial with axis B) and bristles or filaments attached to the central shaft that extend outward in a radial manner. The brush 166 rotates about its central shaft. The present brush 166 has a length LB along the axis A in the length direction of the frame 162. The brush length LB at least corresponds to the width LR of a row 14 of solar panels to be cleaned.

[0110] Any type of brush 166 may be used, for example a nylon brush or a microfibre brush, depending on the type of cleaning to be carried out, e.g. depending on the type of soiling on the solar panels, or the frequency of cleaning. The brush can also be used to remove a layer of freshly fallen snow or blown sand from the panels. The bristles may be straight or helical.

[0111] The brush may be a cylindrical brush formed in a single part (single section), or may be composed of a plurality of brush sections arranged one after the other in the direction of axis A and / or around the shaft. In the first case, a tube core having the desired brush length bears the brush bristles which extend substantially radially. In the case of a brush in multiple sections, the brush bristles are set in place such that they also extend over the joints between the brush sections. Thus, when the brush is composed of a plurality of brush sections, it has a cylindrical surface uniformly covered with brush bristles, such that the entire width LR of a row 14 of solar panels is in contact with brush bristles thereby uniformly cleaning its surface.

[0112] As apparent, the support frame 162 may comprises two end pieces supporting the brush’s rotary shaft, the end parts being connected by lateral profiles. A protective cover 164 fixed to the frame 162 covers the top of the brush 166.

[0113] A motor 190, in particular an electric motor, is fixed to the frame and operatively coupled to the shaft of the brush 166. The motor allows the brush to be selectively driven in rotation.

[0114] The cleaning tool may optionally comprise a second cylindrical brush (not shown), the axis of rotation of which is parallel to, but offset from, the axis of rotation of the brush. The second brush is of the same length as the first and of identical or similar design. The second brush may also be mounted in the support frame (the dimensions of which can be correspondingly adapted).

[0115] The brushes may be identical or different, for example having a different external diameter or be composed of bristles of a different type, for example to enable first rough cleaning of the surface with the assistance of the first brush and finishing with the assistance of the second brush.

[0116] Reference sign 170 indicates a control unit. The control unit 170 is configured to control the various functions of the cleaning apparatus 10, in particular to operate the cleaning head 160, i.e. both the rotation of the brush 166 (via the motor) and its movement with respect to the solar panel(s) to be cleaned (through operation of the actuating means 128, 138, 144, 144’). It is therefore connected, in wired or wireless manner, to the different actuating means 128, 138, 144, 144’ and to the brush motor. To adjust the position of the cleaning tool 166 with respect to the solar panel(s) 12, the control unit 170 further receives measurement signals from a plurality of distance sensors 168 arranged on the cleaning head 160. The distance sensors 168 allow for measurement of the distance between the cleaning head 160 and the panel 12.

[0117] In the present variant, four sensors 168 are arranged in pairs along the length of the frame 162. Each sensor therefore determines the distance between the frame 162 of the cleaning head 160 and the panel 12 at the level at which it is located. The distance is measured substantially on a straight line with each sensor. The control unit 170 is thus configured to control the orientation of the cleaning head 160, primarily on the basis of the signals from the sensors. The control unit 170 further uses the signals from the sensors 168 to keep the cleaning tool 166 (i.e. the brush) at a predetermined distance (or range of distances) from the panels 12. This distance may in particular be calibrated such that the pressure exerted by the brush 166 does not exceed a predetermined threshold, for example of the order of 3000 to 5000 Pa. The sensors 168 may be based any kind of telemetry technology, for example based on depth camera or light beams, in particular LIDAR . They are connected in wired or wireless manner to the control unit 170.

[0118] In general, the control unit 170 may be a microprocessor system comprising various items of hardware and software implementing the above-mentioned functionalities and control principles. The control unit 170 is typically powered by a battery (not shown), which also powers the motor of the brush 166.

[0119] The control unit 170 may further comprise wireless communication means capable of receiving and transmitting data on at least one communication network. Communication may be done by way of a protocol such as wifi, cellular (3G, 4G, 5G), Bluetooth, or their equivalents. It this way, the status of the cleaning head can be determined remotely and its operating parameters modified with e.g. regard to brush control.

[0120] Figs. 5 and 6 represent another embodiment of the present cleaning apparatus 10 mounted on a pick-up truck. The general design and operating principle is the same as described above. The merit of these figures is to show the cleaning apparatus 10 in operation, the cleaning unit being spaced from its suspension arm (compare with Fig.4). One will recognise the tower 120 fixed in the load area of the pickup truck 16, with the support arm 130 extending therefrom and the suspension arm 142 articulated on the support arm 130.

[0121] The actuators 144, 144’ include each belt 145 wound on a spool 147 actuated by a motor 149, in particular an electric motor. Here the cleaning unit 160 / brush 166 has been lowered from the suspension arm 142 by unwinding respective lengths of belt 145 from the corresponding spools 147. This causes the expansion of guiding structure 150 that assists the vertical movements.

[0122] In practice, a certain length of the belt 145 may be unwound, for example about 40 to 50 cm, this is noted LN on the drawings. The suspension arm is then positioned with respect to the solar panels to bring the brush 166 in contact therewith, with the appropriate inclination. As the pickup truck 16 travels along the raw of solar panels, the suspension arm normally remains in the set configuration, and necessary adjustment, due to terrain or panel inclination, are compensated by adjusting actuators 144 and 144’, i.e. by increasing or reducing the length of the belt 145. It is to be noted here that actuators 144 and 144’ can be operated independently, whereby axes A and B may have different inclination.

[0123] In other words, a change of inclination, or distance, of the solar panels can be compensated swiftly by acting on one or both of actuators 144, 144’.

[0124] In Fig.5, the apparatus is in action to clean a row 14 of solar panels mounted on a support 2 with tracker 4, here shown with a tiling angle. The height of the support 2 is noted Hsi . In Fig.6, the support 2 is also provided with tracker function

[0125] 4, but at the time the panels are relatively flat. The support 2 height Hs2 is greater than that of the support 2 in Fig.5 (HS2>HSI).

[0126] As can be seen, the apparatus 10 is able to conveniently accommodate conventional solar panel configurations. The design permits a more accurate and safer control of the brush.

Claims

Claims1 . A cleaning apparatus for solar panels comprising: a mounting structure (114) configured for mounting the apparatus on a mobile unit (16); a support arm (130) moveably connected to the mounting structure, a first drive mechanism (128) being operably connected to said support arm for moving the latter relative to said mounting structure in the vertical direction (Z); a cleaning device (100) mounted to the support arm, comprising: a suspension arm (142) extending from a first end portion (142.1 ), pivotally connected to said support arm to a free second end portion (142.2), along a first axis (A), and associated second drive mechanism (138) for actuating said suspension arm; a cleaning head (160) with a cleaning tool (166) having a main extension along a second axis (B), two actuators (144, 144’) configured to move the cleaning head (160) relative to the suspension arm (142), the actuators connected to the cleaning head at axially opposite fixing points, each actuator being selectively actuatable such that the ends of the cleaning head can move vertically independently from one another, whereby the angular position of the cleaning head can be selectively adjusted separately from the suspension arm.

2. The cleaning apparatus according to claim 1 , further comprising a guiding structure (150) configured to accompany cleaning head (160) displacements along the vertical direction while limiting movements of the cleaning head perpendicularly to the vertical direction.

3. The cleaning apparatus according to claim 2, wherein the guiding structure (150) comprises pivoting levers (152, 154) connected together to form a mechanical linkage allowing vertical movement of the cleaning head relativeto the suspension arm, with limited movement in the direction of said second axis (B) or transversal thereto, in particular a scissor like structure.

4. The cleaning apparatus according to claim 2 or 3 wherein the guiding structure comprises a first reinforcing member (152) arranged to couple one end portion of the suspension arm with a corresponding end portion of the cleaning head and a second reinforcing member (154) arranged to couple the other end portion of the suspension arm with a corresponding portion of the cleaning head.

5. The cleaning apparatus according to the preceding claim, wherein the second reinforcing member (154) includes a pair of V-shaped levers (154.1 , 154.2), one lever being pivotably connected to the suspension arm and the other to the cleaning head.

6. The cleaning apparatus according to any one of claims 2 to 5, wherein the first reinforcing member (152) includes a main lever (152.1 ) pivotally connected at one end to the cleaning tool and engaged at the other in a guide rail (153) of the suspension arm, a complementary lever (152.4) being pivotally connected to the main lever and the suspension arm.

7. The cleaning apparatus according to any one of the preceding claims, wherein the actuators (144, 144’) comprise a flexible link (145), by which the cleaning unit is supported by the suspension arm, the length of flexible link below the suspension arm being adjustable.

8. The cleaning apparatus according to the preceding claim, wherein the flexible link (145) is wound on a spool (147) coupled to a motor (149), to wind or unwind therefrom a length of flexible link.

9. The cleaning apparatus according to any one of the preceding claims, wherein the first and second drive mechanisms comprise a linear actuator.

10. The cleaning apparatus according to any one of the preceding claims, wherein the mounting structure comprises a tower (120) and the support arm (130) is pivotally connected at a first end portion to the tower, the angular position of the support arm being controllable by the first drive mechanism (128).11 . The cleaning apparatus according to any one of the preceding claims, further comprising at least one distance sensor arranged to determine a distance between the cleaning head, preferably the cleaning tool, and a respective surface to be cleaned; and a control unit connected to said at least one distance sensor and configured to adjust the position of the cleaning head, preferably of the cleaning tool, with respect to the surface to be cleaned by actuating at least part of the drive mechanisms and actuators.

12. The cleaning apparatus according to the preceding claim, wherein said at least one distance sensor comprises a LIDAR, or a depth video camera.

13. The cleaning apparatus according to any one of the preceding claims, wherein the cleaning head further comprises driving means for driving, preferably rotating, the cleaning tool.

14. The cleaning apparatus according to any one of the preceding claims, wherein the cleaning tool comprises at least one rotary brush (160) extending across the length of the frame along the first axis (A).

15. The cleaning apparatus according to the preceding claim, wherein the rotary brush is a cylindrical brush having a central shaft parallel to, or concentric with, the first axis (A), and is driven in rotation about the central shaft.

16. The cleaning apparatus according to any one of claims 1 to 13, wherein the cleaning tool comprises a plurality of axial rotary brushes fixed to a cross- piece extending across the length of the frame, the brushes of the plurality of brushes being arranged so as to cover the length of the frame.

17. The cleaning apparatus according to any one of the preceding claims, further comprising a washing liquid tank which feeds nozzles installed on the cleaning head by way of a distribution circuit.

18. The cleaning apparatus according to the preceding claim, further comprising a counterweight (180) configured for balancing the weight of the support arm, cleaning device and preferably guiding structure.

19. The cleaning apparatus according to any one of the preceding claims, wherein the first drive mechanism, the second drive mechanism and / or one or bothactuators (144, 144’) are configured to be powered by hydraulic, electrical energy sources.

20. A mobile unit comprising a cleaning apparatus according to any one of the preceding claims, wherein in particular the mobile unit (16) comprises a chassis supporting the cleaning apparatus and wheels, and preferably an engine or motor, for self-propelling.21 . The mobile unit according to claim 20, wherein the mobile unit (16) is selected from an automobile vehicle, in particular a flat-bed truck or pickup truck, a tractor, a construction truck or an autonomous mobile robot, or a trailer.

22. The mobile unit according to claim 21 , wherein cleaning apparatus is fixed via its mounting structure on the truck flatbed or load area of the pickup truck.

23. The mobile unit according to claim 21 , wherein the mobile unit is a tractor and the mounting structure comprises a coupling interface configured to cooperate with a tractor hitch.

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