The present application claims priority to US provisional application 62/453,053 filed on February 1, 2017 entitled "Panel Cleaning System" which is incorporated by reference in its entirety

Field of the Invention

The invention relates to cleaning systems, and more particularly to cleaning system for cleaning panels, such as solar panels, mirrors and the like.

Background of the Invention

Solar power is a growing source of the clean energy. One of the most common ways to utilize solar energy is to convert the solar power into electricity using solar panels, which are also known as photovoltaic panels or PV panels.

PV panels are currently used as stand-alone panels or in groups of panels, sometime referred to as solar parks or solar farms. Such solar parks produce from a few Kilowatts to hundreds of Mega Watts.

In order to keep the level of efficacy of power conversion in a solar panel, cleaning of the solar panel from dirt, such as dust, on regular basis is required.

Brief Summary of the Invention

It is an object of the invention to provide a system and method for cleaning photovoltaic panels or similar devices such as mirrors, thermo solar-panels and other planar and curved surfaces using an independent, self contained system that does not require any external source or connection during cleaning of the panel. The cleaning system includes two main parts:

(i) a cleaning apparatus which includes a rotating brush, a cleaning fluid reservoir, a power source, and rinsing nozzles; and (ii) a translation mechanism configured to move the cleaning apparatus across the panel, by engagement with edges of the panel or with a dedicated guidance structure (e.g. rails.) According to an embodiment of the invention there is provided a cleaning system for cleaning a panel, the system including a hollow brush containing a cleaning fluid, at least one cleaning fluid distribution mechanism connected to the hollow brush for distribution of the cleaning fluid from the hollow brush, a motor configured to rotate the hollow brush and to pump the cleaning fluid towards the cleaning fluid distribution mechanism, a translation mechanism supporting at least one end of the hollow brush, and configured to move the hollow brush, the cleaning fluid distribution mechanism, and the motor across the panel and a fluid power source, disposed within the hollow brush and providing power to the translation mechanism for translation of the cleaning system and for rotation of the hollow brush.

According to an embodiment of the invention the cleaning system is configured to run at least one cleaning cycle without a need for refill or external energy source. According to an embodiment of the invention the motor is a hydraulic motor.

According to an embodiment of the invention the motor is a pneumatic motor Additionally, the cleaning system may further comprise a docking station.

In an embodiment of the invention the docking station further comprises a brush cleaning mechanism.

Additionally or alternatively, the cleaning system may comprise a mid-way filling station configured for filling fluid into the cleaning system embodiment the cleaning fluid in the cleaning system is water. In an embodiment the cleaning system further includes a filling inlet fluidly connected to the hollow brush for refilling the system with the cleaning fluid and/or with the fluid power source In an embodiment, the motor is a peristaltic motor.

In an embodiment, the translation mechanism of the cleaning system may include a tilting support system. According to an embodiment of the invention there is provide a cleaning system for cleaning a panel the system including a hollow brush having an accumulator disposed therein, at least one cleaning fluid distribution mechanism fluidly connected to the hollow brush, and a translation mechanism supporting the hollow brush and configured to move the hollow brush and the at least one cleaning fluid distribution mechanism across the panel.

In an embodiment the accumulator in the cleaning system is configured to enable at least one cleaning cycle without a need for refill. According to an embodiment of the invention, the translation mechanism of the cleaning system may include a hydraulic motor or a pneumatic motor.

In an embodiment, the cleaning system further includes a filling inlet fluidly connected to the accumulator for filling the accumulator with cleaning fluid and/or energy source

In an embodiment, the hydraulic motor or the pneumatic motor of the cleaning system is a peristaltic motor. Additionally or alternatively, the accumulator in the cleaning system forms an integral part of the hollow brush.

In an embodiment of the invention accumulator is an independent replaceable unit adapted to be disposed within the hollow brush. In an embodiment, the translation mechanism of the cleaning system includes a tilting support system.

According to an embodiment of the invention there is provided a method for cleaning a panel, the method comprising, providing a cleaning system according to any embodiment of the invention, filling the cleaning system with cleaning fluid and energy source, triggering the start of the translating the system across the panel, and while the cleaning system is translated across the panel, rotate the brush. According to an embodiment of the invention the method for cleaning of a panel according further comprises distributing cleaning fluid from the cleaning system while the cleaning system is translated across the panel.

According to an embodiment of the invention there is provided a system for cleaning of a panel including a translation mechanism configured to move the cleaning system across the panel, a hollow brush containing cleaning fluid and supported by the translation mechanism, at least one cleaning fluid distribution mechanism connected to the hollow brush, an electrical power source, providing power to the translation of the cleaning system and rotation of the hollow brush, at least one motor configured to rotate the hollow brush to pump the cleaning fluid towards the cleaning fluid distribution mechanism, and wherein the system is configured to run at least one cleaning cycle without a need for refill or external energy source. Additionally or alternatively, according to an embodiment of the invention the system for cleaning a panel is configured to perform cleaning action without activating the fluid distribution mechanism.

In an embodiment, translation mechanism of the cleaning system includes a tilting support system

According to an embodiment of the invention there is provided a system for cleaning of a panel including a translation mechanism configured to move the cleaning system across the panel, a brush supported by the translation mechanism and configured to rotate, a power source, providing power to the translation of the cleaning system and rotation of the brush, at least one motor configured to rotate the hollow brush and to pump the cleaning fluid towards the cleaning fluid distribution mechanism, and wherein the translation mechanism comprises a tilting support system.

In an embodiment of the invention, the system for cleaning of a panel includes a translation mechanism is self aligning.

According to an embodiment of the invention there is provided a system for cleaning of a panel comprising a translation mechanism configured to move the cleaning system across the panel, a hollow brush containing cleaning fluid and supported by the translation mechamsm, at least one cleaning fluid distribution mechanism connected to the hollow brush, a fluid power source, embedded within the hollow brush and providing power for the translation of the cleaning system and rotation of the hollow brush, a motor configured to rotate the hollow brush to pump the cleaning fluid towards the cleaning fluid distribution mechanism; and wherein the system is configured to run at least one cleaning cycle without a need for refill or external energy source. According to an embodiment of the invention the motor of the system for cleaning of a panel is a hydraulic motor or a pneumatic motor.

Additionally the system for cleaning of a panel may include a docking station. According to an embodiment of the invention the cleaning fluid is water.

Additionally the system according embodiments of the invention may include a filling inlet for refilling the system with cleaning fluid and energy source According to embodiment of the invention the motor is a peristaltic motor.

According to an embodiment of the invention there is provided a system for cleaning of a panel comprising a translation mechanism configured to move the cleaning system across the panel; a hollow brush containing an accumulator and supported by the translation mechanism; at least one cleaning fluid distribution mechanism connected to the hollow brush; and wherein the accumulator is configured to enable at least one cleaning cycle without a need for refill.

According to an embodiment of the invention the translation mechanism of the system for cleaning of a panel includes a hydraulic or a pneumatic motor.

According to an embodiment of the invention there is provided a method of cleaning of a panel comprising providing a cleaning system for panels as described herein and above, filling the system with cleaning fluid and energy source; triggering the start of the cleaning; and while the cleaning system is translated across the panel, rotate the brush.

Alternatively or additionally cleaning of a panel according may comprise dripping cleaning fluid while the system is translated across the panel.

Brief Description of the Drawings

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

Fig. 1 is a schematic illustration of a system for cleaning panels according to an embodiment of the invention;

Fig. 1A schematically shows a spiral brush useful in the system of Fig. 1, according to an embodiment of the invention;

Figs. 2A and 2B are schematic perspective illustrations showing a support roller subsystem and a translation mechanism of the system of Fig. 1, respectively;

Fig. 2C is a schematic illustration of a translation mechanism of the system in Fig. 1 in which an electric driving motor is used for driving the system.

Fig. 3 is a schematic illustration of an energy source and watering system forming part of the system of Fig. 1;

Fig. 4 is a schematic illustration of a system for cleaning panels according to another embodiment of the invention; Fig. 5 is an illustration of a translation mechanism forming part of the system of Fig. 4;

Fig. 6A and 6B are schematic perspective illustrations showing further detail of the translation mechanism of Fig. 5 and of a direction change mechanism thereof;

Fig.s 7A and 7B are schematic illustrations of a system for cleaning panels according to an a third embodiment of the invention; and

Fig. 8 is a schematic illustration of a system for cleaning curved panels according to an embodiment of the invention.

Fig. 9 is a schematic illustration of a mid-way filling station for a panel cleaning system according to any embodiment of the present invention

Detailed Description of preferred embodiments of the Invention

The principles of the inventive cleaning system, and of methods of use thereof, may be better understood with reference to the drawings and the accompanying description.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. Reference is now made to Fig. 1 which is a schematic illustration of a system 100 for cleaning panels according to an embodiment of the invention. In Fig. 1, system 100 is shown installed on a panel 50. Panel 50 may be a PV panel, a solar collector used for water heating, a large mirror (e.g. glass mirror), or any other type of panel. Although in the illustrated embodiment the panel is presented as a flat panel, it is appreciated that the invention may also be implemented on curved panels.

Preferably, in order to facilitate dripping or spreading of cleaning fluid, panel 50 may be inclined at an angle relative to the ground, as illustrated in Fig. 1. In other embodiments, panel 50 may be disposed horizontally. System 100 is configured to move back and forth across panel 50 in a direction 75. The embodiment shown in Fig. 1 is particularly useful when cleaning a group of panels located adjacent one another, for example in a solar farm, because multiple adjacent panels may be cleaned using a single system.

In another embodiment, system 100 may be installed on an articulated arm (not shown) which would allow for non-Cartesian movement, such as radial movement similar to the movement of windshield wipers in a car. Such a structure may be advantageous in some configurations, for example when cleaning stand-alone panels.

In the embodiment shown in Fig. 1 system 100 includes a cylindrically shaped, hollow brush 120 having a longitudinal axis 121 and bristles 125 extending radially generally perpendicularly to the longitudinal axis. The hollow brush 120 extends along the full height of solar panel 50, or along the full height of an area to be cleaned. Hollow brush 120 may also contain a cleaning fluid and a power source for operation thereof, as described below in further detail with respect to Fig. 3.

In the embodiment shown in Fig. 1, hollow brush 120 is supported at a first end 142 thereof by a support rollers subsystem 140, which rides on the frame or edge of panel 50, as illustrated, or may ride on a dedicated infrastructure (not shown), such as dedicated rails. The second, opposing end 132 of hollow brush 120 is supported by a translation mechanism 130. Support rollers subsystem 140 and translation mechanism 130 are collectively referred to herein as translation subsystem 150. It is appreciated that the locations of support rollers subsystem 140 and of translation mechanism 130 may be reversed, such that support roller subsystem 140 is disposed on the second end 132 of the hollow brush 120, and translation mechanism 130 is disposed on the first end 142 of the brush 120. In some embodiments, translation mechanisms 130 may support both ends 132 and 142, and support rollers subsystems 140 may be obviated.

Hollow brush 120 includes a brush body 160, which may include a cleaning fluid reservoir and the power source as described in further detail hereinbelow, and a cylindrical brush 170 fixedly attached to brush body 160, as explained in further detail below. In some embodiments, brush body 160 includes, or encloses, a storage tank for storing cleaning fluid and an accumulator that serves as an energy storage (not shown). Hollow brash 120 may be made from commercially available brushes. Some examples of commercially available brashes that can be used for the making. Hollow brush 120 include Spiral brushes available from Involve Marketing of at 151-4-5 Mutiara Puchong Business Centre, Jalan Pichong, Batu 6½, 58200 Kuala Lumpur, Malasia flittp://www.involveml t.com/2012/04/spiral-bmsh-coil-strip-brush-coil.html) and Spiral brashes available from AMBIKA TECHNO INDUSTRIES of Plot No. 2- B/3, S.M.I.E., 20/2, Phase-1, Opposite Orient Fan, Smie Faridabad- 121006, Haryana, India (¾ttp://www.directindustrv.com/prod/ambika-tecrmo-indus es/product-54 1416269.html ). Such spiral brushes may be mounted onto the brush body 160 and affixed thereto by any suitable process, such as welding, bonding, riveting etc.

Hollow brush 120 may also be made from linear strip brashes commercially available from Societa Italiana Tcnospazzole of Bologna, Italy (http://www.sitbrash.corn/fa

Brushes.php). Such linear brashes can be affixed to the cylindrical body 160 of cylindrically shaped hollow brash 120 by appropriate adapters or by providing appropriate longitudinal grooves (not shown) in the cylindrical body 160 , sliding appropiate ridges of the linear brashes into the grooves, and affixing the brush in the appropriate position.

Alternatively, as shown in Fig. 1 A, a cylindrically shaped, hollow brush 120 may be formed of an extruded pipe 192 having spiral grooves 194 formed thereon using any suitable means, such as extruding using appropriately inclined nozzles, milled, or plastically forming a helix by torquing the extrusion. Flexible brash strips 196 may be inserted into grooves 194 thus forming cylindrically shaped hollow brash 120 equipped with a spiral brash or brashes. As would be apparent to a person skilled in the art, extruded pipe 192 serve as cylindrical body 160 of a cylindrically shaped, hollow brush 120.

In an embodiment a cylindrical body 160 with straight strips of bristles attached thereto is warped in order to get spiral brashes.

As would be apparent to a person skilled in the art hollow brush 120 does not have to be cylindrical (with circular cross section), as described in conjunction to Fig 1, but could have any other cross section that would allow rotation of the hollow brush, for instance octagonal, rectangular and the like. A watering subsystem 180 may be used for spreading cleaning fluid in the path of the hollow brush 120. In the illustrated embodiment, the watering subsystem 180 includes a pipe with holes or nozzles distributed along its length (not shown) connected to the translation subsystem 150 and fluidly connected to the cleaning fluid within the hollow brush 120 as will be further detailed below. In other embodiments, which are particularly useful when the panel is inclined, a water outlet may be provided only at the upper part of the panel, and the water may drip or flow along the panel towards the base thereof under gravitational pull.

Reference is now made to Figs. 2A and 2B, which are schematic perspective illustrations showing support roller subsystem 140 and a translation mechanism 130 of the system 100, respectively.

As shown in Fig. 2 A, support rollers subsystem 140 may be connected, for example via bearing 210, to hollow brush 120, thus allowing for the rotation of the brush relative to support rollers subsystem 140. In the illustrated embodiment, support roller subsystem 140 has a chassis 220 connected on one side to the housing of bearing 210. Guidance rollers 230, here illustrated as four such rollers, are attached to chassis 220 and are configured to roll on the framework of panel 50 or on a dedicated infrastructure when system 100 moves across panel 50. Support rollers subsystem 140 is driven by the rotation of hollow brush 120 via a transmission system 240. In the illustrated embodiment, the transmission system 240 is a belt and pulley system, but other types of transmission would be apparent to a person skilled in the art. In the illustrated embodiment the belt may also be used to provide support and traction against the framework of panel 50 or the dedicate rail, similarly to the traction provided by tracks of a tank or other tracked heavy vehicle.

An inlet port 250 may be connected to the inner part of bearing 210 and fluidly connected to the reservoir disposed within brush body 160 in order to provide cleaning fluid and/or compressed air.

As discussed hereinabove, the role of translation mechanism 130 is to use energy provided by the power source stored within hollow brush 120 in order to move the translation subsystem 150 and hollow brush 120 across the panel, while concurrently driving the rotation of hollow brush 120 and pumping cleaning fluid from the reservoir within hollow brush 120 onto watering subsystem 180, which results in wetting/rinsing and brashing of the panel while the system moves across the panel - thereby affecting panel cleaning.

In the embodiment shown in Fig. 2B, translation mechanism 130 includes a chassis 260. A hydraulic motor 270 is fixed to chassis 260. Rollers 280 are attached to chassis 260, here shown as four rollers, which rollers are configured to roll on the framework of panel 50 or on dedicated infrastructure when system 100 moves across panel 50. Rollers 280 are driven by the rotation of hydraulic motor 270 via a transmission system 290. In the embodiment shown in Fig. 2B a belt and pulley system serves as the transmission system 290, but other types of transmission systems (e.g a gear system) may be used as would be apparent to a person skilled in the art.

As would be apparent to a person skilled in the art, hydraulic motor 270 may be replaced by a pneumatic motor, which may be pneumatically driven and may rotate a water pump that pushes the cleaning fluid towards watering sub system 180.

In some embodiments, motor 270 is a peristaltic type motor, such as described in US patent number 4,997,347, which is incorporated herein by reference. Alternatively, other types of motors, such as a turbine, a piston motor, a gear motor, and a vane type motor may be used.

In some embodiments, watering sub system 180 includes a pipe 182 extending along hollow brush 120. The pipe is attached to, and is fluidly connected at one end 184, to an outlet of hydraulic motor 270. At the other end 186 (Fig. 2 A) the pipe 182 is sealed. The pipe 182 includes small holes or nozzles (not shown) through which the cleaning fluid drips out of the pipe 182 and onto the brush or the panel being cleaned. For further structural strength, the other end 186 of pipe 182 may also be attached to, or supported by, chassis 220.

As mentioned above, in some embodiments, one or more water outlet may be provided only at the upper part of the panel, such that water may drip or flow along the panel towards the base thereof under gravitational pull. This embodiment is particularly useful when the panel is inclined, and reduces the amount of energy required to rinse the panel being cleaned.

In an embodiment, system 100 may be operated in a 'dry' mode, where no water is applied to panel 50 and cleaning is achieved by the movement and rotation of hollow brush 120.

In some embodiments, a docking station as described hereinbelow may facilitate control of the operation of system 100 in 'dry' mode. For instance, when the hydraulic motor is a pneumatic motor, activating the system, without filling water will launch a dry cleaning mode.

Operating the system 100 in 'dry' mode or in a combined 'dry' and 'wet' mode may provide some advantages such as reduction of the amount of water used, and fast cleaning of dust and particles for which wetting is not needed.

In some embodiments, an electric driving motor may be used to drive system 100, either in addition or in place of hydraulic motor 270 as will be detailed further below.

Reference is now made to Fig. 2C which shows a translation mechanism 132, similar to translation mechanism 130, in which an electric driving motor is used to drive the system in lieu of hydraulic/pneumatic motor 270. Translation mechanism 132 uses electrical energy to move (energy may be supplied by a battery, not shown) translation subsystem 150 and brush 120 across the panel, while at the same time driving the rotation of hollow brush 120 and pumping cleaning fluid from the reservoir within hollow brush 120 onto watering subsystem 180 (as shown in Fig. 2B), which results in wetting/rinsing and crashing the panel while the system moves across the panel - thereby affecting panel cleaning. As would be apparent to a person skilled in the art the role of the electrical motor can be split among two electrical motor, namely one that drives translation subsystem 150 and brash 120 across the panel, as well as driving the rotation of the hollow brush 120 and another electrical motor pumping cleaning fluid from the reservoir within the hollow brash 120 onto watering subsystem 180.

In the embodiment shown in Fig. 2C, translation mechanism 132 has a chassis 262. Electric motor 272 is fixed to chassis 262. In the illustrated embodiment, rollers 282 are attached to chassis 262 and are configured to roll on the framework of panel 50 or on a dedicated infrastructure (as shown in Fig. 1) when system 100 moves across panel 50. Rollers 282 are driven by the rotation of electric motor 272 via a transmission system 292. In the embodiment shown in Fig. 2C, a gear driven chain sprocket wheel system serves as the transmission system but other types of transmission (e.g a gear system) may be used as would be apparent to a person skilled in the art. Reference is now made to Fig. 3 which is a schematic illustration of an energy source and watering system forming part of system 100, which does not include the brush and other mechanical elements of system 100. In the embodiment illustrated in Fig. 3, system 100 includes an accumulator 310 which has a water chamber 320 and air chamber 330. Preferably the two chambers are separated by a membrane 335 or piston (not shown). However, if the accumulator 310 is inclined or is vertical relative to the ground such that air chamber 330 is disposed above water chamber 320, separation of the accumulator by a membrane or piston is not needed.

Water chamber 320 is filled via an inlet hose/ valve 340.

Optionally, compressed air may be pumped into air chamber 330 via an air valve

350. Air pressure in air chamber 330, which may be in the range of 2-10 atmospheres, may be caused by pumping water into water chamber 320 which will cause reduction in air volume, hence raising the pressure in air chamber 330 to the desired pressure level.

Accumulator 310 may be equipped with a pressure relief valve for safety (not shown).

In an embodiment the accumulator forms an integral part of hollow brush 120. In such case, the body of hollow brush 120 serves also as the body of accumulator 310.

Alternatively, air is not pumped into air chamber 330 via an air valve but rather is a built as a replaceable pre-filled gas container/gas cylinder which is inserted into the accumulator and is replaced when it is empty. Preferably, such pre-filled containers will be manufactured and filled in a dedicated facility.

In some embodiments, accumulator 310 is not an integral part of system 100 and is a replaceable unit containing compressed air and cleaning fluid.

Operation sequence of the energy source and watering system of Fig 3: Preparation:

Water chamber 320 is filled via inlet hose/valve 340 until water chamber 320 includes the required or desired volume of water/cleaning fluid.

Optionally, air is pumped into air chamber 330 via air valve 350 until a desired internal pressure is achieved. As a non-limiting example, for cleaning a panel of size lm by 2m, 0.5-1 liters of cleaning fluid are required during a 10 second cleaning period. Filling a 30 liters water chamber 320 with about 20 liters of cleaning fluid and pumping 10 liters at 9 bar of compressed air into the water chamber or the air chamber, as appropriate is sufficient for cleaning of 20 panels of that size, assuming a motor working pressure of 3 bar, which provides 15-30 watt of hydraulic motor power.

Operation:

Air pressure in air chamber 330 pushes cleaning fluid (e.g. water) from water chamber 320 into hydraulic motor 270, causing the motor to turn and rotate the brush, as well as drive translation mechanism 130, thus moving hollow brush 120 across panel 50.

The cleaning fluid exits from hydraulic motor 270 into watering subsystem 180 subsystem, which drips or spreads the water onto the panel during rotation of the brush, thereby cleaning the panel 50.

Reference is now made to Fig. 4, which is a schematic illustration of a system 400 for cleaning panels according to another embodiment of the invention. In Fig. 4, system 400 is shown as installed on a panel 50. It should be noted that in Fig. 4, in the area below system 400, the black part of panel 50 was removed for better visibility of the different parts of system 400. Panel 50 may be a PV panel, a solar collector used for water heating, a large mirror (e.g. glass mirror), or other type of panel. Although in the illustrated embodiment the panel is presented as a flat panel, it is appreciated that the invention may also be implemented on curved panels. In some embodiments, in order to facilitate dripping or spreading of cleaning fluid, and as shown in Fig. 1, panel 50 may be inclined at an angle relative to the ground System 400 is configured to move back and forth across panel 50 in a direction 75.

In the embodiment shown in Fig. 4, system 400 includes a hollow brush. The brush 120 extends along the full height of solar panel 50, or along the full height of an area to be cleaned. Hollow brush 120 may also contain a cleaning fluid and a power source for operation of the brush, substantially as described with respect to the embodiment of Fig. 1. The brush shown in the embodiment of Fig. 4 is a spiral brush as described in conjunction with Fig. 1. As in the embodiment shown in Fig. 1, in the embodiment illustrated in Fig. 4, the hollow brush 120 includes a brush body 160, which may contain cleaning fluid and the power source as described hereinabove with respect to Fig. 1. Hollow brush 120 may also include a storage tank (as described in conjunction to Fig. 3) for the cleaning fluid and an accumulator. The hollow brush 120 further includes a cylindrical brush 170 rigidly attached to brush body 160.

System 400 also includes a watering subsystem (not shown) which drips water onto the panel by gravitational force. The system may also include other types of watering sub systems, for instance a pipe based watering sub system similar to watering sub system 180 described in reference to Fig. 1.

Unlike the embodiment shown in Fig. 1, in the embodiment illustrated in Fig. 4 hollow brush 120 hangs from an upper portion 432 of panel 50, while a bottom edge 442 of hollow brush 120 is unattached, or is freely suspended, so that the bottom edge 442 may swing slightly while being led or trailed by an upper edge 432 of hollow brush 120. Such an arrangement, as well as the one described in conjunction to Figs. 7A and 7B may be referred to as a tilting support system. One advantage of such an arrangement is that it is flexible as far as traction and drag forces and does not demand synchronized driving of the upper and lower edges, or parallel and perfectly aligned rails. In addition, the pendulum like movement of the lower edge 442 of the brush adds to the efficiency of cleaning by directing the dirt downward. At the upper edge 432 hollow brush 120 is supported and driven by a translation mechanism 430. At the lower edge 432, hollow brush 120 is supported by a support roller sub system 440, which is adapted to ride on the frame of panel 50 or on dedicated infrastructure (not shown).

Translation mechanism 430 and support rollers subsystem 440 are collectively referred herein as translation subsystem 450.

Support roller subs system 440 may include a single wheel 444, which in some embodiments is axially hinged, for example by means of a bearing, to the body of hollow brush 120, such that the brush 120 and the wheel 444 can rotate independently of each other. The perimeter of the wheel 444 may be rigid (e.g. made of metal such as aluminum or steel), or may be covered with a more flexible material, such as rubber or a pneumatic tire. Alternatively, support roller sub system 440 may be omitted such that hollow brush 120 is self supported, for example on the bristles of cylindrical brush 170 which form part of hollow brush 120.

Translation mechanism 430 may be of the same type as translation mechanism 130 (Fig. 1) or may be of a different type such as the one described in conjunction to Fig. 2C. Translation mechanism 430 may have an outlet through which cleaning fluid drips by gravity or supplied to a watering subsystem, in a similar manner to that described hereinabove with respect to Figs. 1 and 2B.

The system 400 illustrated in Fig. 4 includes a different mechanism than that shown in Fig. 1, and includes a system for direction change, as will be detailed below.

Reference is now made to Fig. 5, which is an illustration of translation mechanism 430 according to the embodiment shown in Fig. 4.

The main role of translation mechanism 430 is to use energy provided by the power source stored within hollow brush 120 in order to move the translation subsystem 430 together with hollow brush 120 across the panel, while concurrently driving the rotation of hollow brush 120 and pumping cleaning fluid from the reservoir within hollow brush 120 onto the watering subsystem, which results in wetting/rinsing and broshing of the panel while the system moves across the panel— thereby affecting panel cleaning.

In the embodiment shown in Fig. 5 translation mechanism 430 includes a hydraulic or pneumatic motor 570. Mechanical and fluid connections of hydraulic/pneumatic motor 570 to hollow brush 120 are similar to those described with respect to hydraulic motor 270 (Fig. 2A). Rollers 580 are attached to a chassis 560 and are configured to roll on the framework of panel 50 or on a dedicated infrastructure, as described hereinabove. In the embodiment shown in Fig. 5, rollers 580 include a main wheel 581, preferably made of rubber, which is fixedly connected to a shaft 615which provides traction. On either side of main wheel 581 is a side wheel 582. Side wheels 582 are mounted on a tandem structure 584 which facilitates the swinging of the bottom edge 442 (Fig. 4) of hollow brush 120 as described above. A transmission system 590, forming part of the translation mechanism 430, includes a direction changing mechanism for changing the direction of movement of cleaning system 400 as will be detailed below in connection to Figs. 6 A and 6B. In the embodiment shown in Fig. 5, two motions stops 597 are rigidly connected to the frame or edge of panel 50 or to the dedicated infrastructure, as will be further detailed herein below with respect to Figs. 6A and 6B.

Reference is now made to Figs. 6A and 6B, which are perspective view illustrations showing further detail of transmission system 590 and its direction changing mechanism.

In the embodiment shown in Figs. 5, 6A, and 6B, transmission system 590 includes a center gear 610 driven by the hydraulic/pneumatic motor 570, as well as an upper gear 620 and a lower gear 630 fixedly coupled to shaft 615. The whole transmission system 590 is rotatable together with a gear carrier 640 hence resulting in vertical movement of upper gear 620 and lower gear 630 relative to center gear 610, such that upper gear 620 and lower gear 630 alternately mesh with center gear 610, affecting shaft 615 and determining a direction of rotation of wheel 581.

In the illustrated embodiment, upper gear 620, lower gear 630 and center gear 610 are bevel gears. However, other types of matching gears may be used. As would be clear to a person skilled in the art, when upper gear 620 is meshed with center gear 610 (as shown in Fig. 6A), main wheel 581 rotates in one direction, whereas when lower gear 630 is meshed with center gear 610 (as shown in Fig. 6B) main wheel 581 rotates in the opposite direction. Consequently, the mechanism of gears 610, 620, and 630, leads to a change in the direction of movement of cleaning system 400. Toggling of gear meshing between upper gear 620 and lower gear 630 can be accomplished by means of a mechanism including a lever 650 and a spring 660 that causes swinging of the gear carrier 640 which in turn meshes one of upper gear 620 and lower gear 630 with main gear 610. Switching the position of lever 650 may be driven by motion stops 597 (Fig. 5). More specifically, when cleaning system 400 reaches one extremity of its range of motion, the position of lever 650 is switched by engagement with the adjacent motion stop 597, and the direction of motion is switched.

Reference is now made Fig.7 A which shows a schematic illustration of a system 700 for cleaning panels according to an embodiment of the invention.

In the embodiment shown in Fig. 7 A, translation mechanism 430 is as described hereinabove with respect to Fig. 4. However, a support rollers sub system 460 supports the opposing edge 462 of hollow brush 120. In Fig. 7 A, hollow brush 120 is shown when moving in direction 470 across panel 50. As seen in Fig.7A, translation mechanism 430 drags the upper edge 464 of hollow brush 120, causing the brush to be tilted relative to the frame of the panel, such that the lower portion of brush 120 and edge 462 'lags' behind translation mechanism 430. The inventor have found that such an arrangement is advantageous when working in dry mode, as it pushes the dirt being cleaned towards the lower end of the panel, which increases the effectiveness of removing dirt from the panel. It should be noted that the unique structure enables 'auto-adjustment' of the tilt angle in response to the quantity of dirt on panel 50, such that a greater tilt angle is formed when there is a large quantity of dirt due to the friction and drag caused by the dirt. In other words - the system is 'self aligning'. As would be apparent to a person skilled in the art, when hollow brush 120 is in motion across panel 50 in the opposite direction to direction 470 the same titling effect described above occurs in the opposite direction.

Reference is now made to Fig.7B which shows, in greater detail support rollers subsystem 460. In the illustrated embodiment, the trailing side of hollow brush 120 is connected to a center part 465 of support rollers subsystem 460 such that center part 465 can rotate about the longitudinal axis 466 of hollow brush 120. For example, the center part may be fixedly connected to the center of bearing 467 fixedly connected to edge 462 of hollow brush 120. Center part 465 is flexibly (for instance hinged) connected to one side 471 of each of two rods 470. A pulley subsystem 480 is connected via hinge to the opposing end 472 of each rod 470. Each pulley subsystem is supported, at a portion thereof distal to rod 470, supported on a frame 490 preferably made of steel. This arrangement allows supporting the brush in a plane parallel to that of the panel, while allowing the brush to rotate about its longitudinal axis, and about an axis perpendicular to the plane of the panel, in a pendulum-type motion. This arrangement may also compensate for slight variations in the distance between the lower rail of frame 490 (as it appears in Fig. 7B) and upper rail, which otherwise might have led to de-railing of the cleaning system.

Other elements of system 700 are similar to elements described hereinabove with respect to systems 100 and 400.

Reference is now made to Fig. 8 which is a schematic illustration of a system for cleaning curved panels. In the illustrated embodiment a cleaning system 800 is shown disposed on a curved panel 750. System 800 includes three hollow brushes 720A, 720B, and 720C, connected to one another by connection elements 760.

Connection elements 760 are configured for delivering both power and cleaning fluid between consecutive hollow brushes 720s, as will be explained below. Enlargement A shows an example of such a connection element 760, including a universal joint 770 which transmits rotational motion, and a flexible hose 780 through which cleaning fluid (or cleaning fluid and compressed air) is pushed towards the next hollow brush (e.g. from brush 720A to brush 720B).

Other elements of system 800 are similar to elements described hereinabove with respect to systems 100 and 400, and therefore not described here.

Each of systems 100, 400, 700 and 800 may be configured to connect to a docking station (not shown), which may be connected to a supply source of cleaning fluid and/or compressed air. Upon completion of a cleaning cycle, systems 100, 400, 700 or 800 may connect to the docking station in order to be refilled with cleaning fluid and/or compressed air.

In this application - a cleaning cycle is the process of cleaning a pre-defined number of panels in a row of panels. The predefined number may be all the panels between one end of the row of panels to the other end, from one end of the row to the same end when cleaning is done back and forth, cleaning the panel betwen docking stations or filling stations, cleaning a single panels or any other combination desired.

The docking station may comprise a designated "parking" location, preferably at one end of the panel or on a dedicated structure frame. In some embodiments, the docking station also includes a hydraulic/pneumatic quick connection valve.

The docking station may be fed, or refilled, through a supply line (hose) of hydraulic fluid, such as cleaning fluid or water, or compressed air. A number of docking stations associated with different panels, may be connected to a single pressure source or valve.

For systems powered by hydraulic or pneumatic pressure, when connected and mechanically latched, the system may stay still whenever there is no pressure built within hollow brush 120. By activating the pressure source of the docking station or opening the a valve of the pressure source, pressure of hydraulic fluid or pneumatic gas is pushed through to the devices or apparatus connected to the docking station, resulting in pressure building up in each hollow brush 120 . Achieving a certain pre-defined pressure level in hollow brush 120 may trigger a cleaning cycle.

In some embodiments, the quick connection valve or latching mechanism is set to a pre-determined pressure level, and when this pressure level is reached, cleaning system 100/400/700/800 connected to the docking station or the valve are automatically released to move and start the cleaning operation, thus forming a simple hydraulic/pneumatic "launch control" mechanism. Thus, timing of filling system 100, 400 700 or 800 with fluid and/or compressed air may be used to dictate the time at which the system begins a cleaning cycle. Determination of the timing can be carried out manually, or electronically and remotely by a controller in communication with a remote terminal. As would be apparent to a person skilled in the art, other ways of control may be used - such as individual valves per device, wireless control etc.

In some embodiments, the pressure sources/valves of the docking stations shuts down prior to cleaning systems 100/400/700/800 finishing their travel back and forth across the panel. As such, when the cleaning systems 100/400/700/800 return to the docking stations a smooth effortless attachment between the system and the docking station is possible, and the cleaning system 100/400/700/800 is again latched to the docking station, until next launch.

When an electrical motor is used , such as in the embodiment shown in Fig. 2C, the docking station may include a electrical connection which may be engaged during docking of the system in order to supply power, for example to a battery of the electrical motor. Power can be supplied to the electrical connection from main line connected to the docking system, or from a solar panel (either from solar panel 50 being cleaned, or a different solar panel)

In some embodiments, the docking station may include a brush cleaning mechanism, such as a brush or an impact mechanism that hits or touches the bristles of hollow brush 120 to cause removal of dirt and dust from the bristles, thus thereby cleaning of hollow brush 120. Additionally or alternatively, the docking station may include a dedicated structure, such as a comb or steel cable. When hollow brush 120 approaches the docking station, which typically occurs while the brush is rotating, the tips of the bristles hit the dedicated structure, and the impact results removal of dirt and dust from the bristles.

Reference is now made to Fig. 9, which is a schematic illustration of a mid-way filling station 900 for a panel cleaning system according to any embodiment of the present invention. Such a mid-way filling station is particularly useful when cleaning a long array of panels, as it enables a reduction in the quantity of water the cleaning system has to carry while operating, and reduces the weight applied to the panel being cleaned or to its infrastructure by the cleaning system. In addition, such an arrangement allows cleaning the long array of panels in an almost continuous action.

In the embodiment shown in Fig.9, a translation mechanism 910, of a panel cleaning system according to any of the embodiments described hereinabove, is supported by a frame 930. Translation mechanism 910 is also equipped with a funnel element 940 having a wide end 942 and a narrow end 944 such that the wide end 944 points up and is disposed slightly outside of frame 930. In the embodiment shown, mid- way filling station 920 includes a water source (not shown), a pipe 950 curved at an angle suitable for engaging the middle of funnel element 940 when translation mechanism 910 is in line with the location of mid- way filling station, and an actuating lever 960. In the embodiment shown, water filling may occur when translation mechanism 910, while in motion, reaches a point so as to push lever 960. Pushing of the lever enables water to flow into funnel element 940 thereby to fill the cleaning system. Water flow into the system continues until the lever 960 is pushed back, by the advancing translation mechanism. Alternatively, as would be apparent to person skilled in the art, filling of water can be accomplished while the panel cleaning system is stationary, by adding appropriate sensors and commands (e.g Magnetic switch that activates an electric power faucet).

As would be apparent to a person skilled in the art, mid-way filling station may also be utilized for filling power source such as compressed air via appropriate valve and connector (not shown).

It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.