CLEANING SYSTEM AND PROCEDURES FOR A SOLAR POWER PLANT

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to cleaning for solar panel power plants, in particular photovoltaic panels. STATE OF THE ART

[0002] Currently, there are various solar panels available for energy production. A solar panel is a device that converts part of the sun's radiation into thermal or electrical energy, using solar thermal collectors or photovoltaic cells respectively. In particular, some solar panels are hybrid and combine the two technologies mentioned above to produce both electricity and heat. The grouping of many solar panels in a single location is called a power plant.

[0003] Furthermore, the development of new power plants is hampered by the need to preserve as much potentially arable land as possible. For this reason, there is currently a strong trend towards installing new photovoltaic power plants on water, above artificial basins, reservoirs, dams, or canals. These types of power plants are called "floating power plants" to distinguish them from "land-based power plants," where the solar panels are anchored to the ground.

[0004] One of the particularities of floating power plants is that the panels rest on anchored floats. This configuration allows the entire power plant to be kept relatively stable. However, it is difficult to maintain a stable level, or even the orientation or inclination of the panels. The relative height of a panel in relation to adjacent panels can vary by several centimeters and degrees depending on the swell, the passage of a motorboat nearby, or due to occasional excess weight, for example a group of birds. This random variation in the positioning of the panels relative to each other poses various problems, particularly for cleaning the panels.

[0005] Furthermore, power plants attract colonies of birds that can dirty the solar panels with their droppings. It is therefore necessary to use suitable cleaning methods to keep the power plants running.

[0006] The plants can be equipped with sprinklers distributed along the edges of the panels for liquid spray cleaning. However, multiple sprinklers must be placed along the panels. Furthermore, cleaning is inefficient because bird droppings cannot be properly removed by a simple jet of liquid.

[0007] Some power plants are equipped with automated cleaning robots. For example, international application WO 2009 / 001225 can be cited.

[0008] For example, the robots are equipped with brushes, drive wheels, and rotating guide rollers located in contact with the edges of the solar panels to guide the robots along the panels. However, these robots are designed to clean a single panel and cannot move from one row of panels to another.

[0009] Some robots are autonomous and can move along a defined path stored in memory. They are usually equipped with sensors to prevent them from falling or hitting obstacles. However, these robots also cannot move from one panel to another without human intervention.

[0010] IlThere are still power plants that use cleaning drones to spray liquid on the panels. However, these drones must be guided by a person during cleaning. They can optionally be self-guided by a guidance program, but such a program is complex to ensure robust handling and complete autonomy of the drone. In addition, the drone must be equipped with complex electronics to control its flight, particularly using a satellite geolocation system, and to detect obstacles. The drone must be equipped with sufficiently powerful batteries to allow it to completely clean several panels spread over several rows. The distance of the drone from the solar panels is difficult to maintain constant.Thus, these drones are rather equipped with a liquid or air diffuser in order to provide remote cleaning and can be difficult to equip with brushes which require permanent contact between the drone and the solar panel.

[0011] Further examples include patent documents KR20210021690, CN204231280 and US2019 / 372513, which disclose a cable-driven robot for cleaning a single solar panel on which it is mounted.

[0012] Another example is US patent application US2017 / 133978, which discloses a solar panel cleaning system comprising a main frame, a cleaning trolley, and a rotating drum that winds and unwinds insulated metal cables to pull the cleaning trolley along the frame. Furthermore, the cleaning system can be moved from one row of solar panels to another by a system of rails and switches that function like railway tracks. However, such a cleaning system is complex to implement. SUMMARY OF THE INVENTION

[0013] An object of the invention is to overcome these drawbacks, and more particularly to provide cleaning means for solar panels equipped with cleaning devices capable of passing from one panel to another and which are simple to produce.

[0014] Another object of the invention is to provide cleaning means suitable for floating and land-based power plants.

[0015] Other objects, features and advantages of the present invention will become apparent from the following description and accompanying drawings.

[0016] According to one aspect of the invention, there is provided a cleaning system for a solar panel power station, comprising at least one device for cleaning at least one solar panel.

[0017] The system comprises an apparatus for transporting said at least one cleaning device by towing cable.

[0018] The transport device comprises a traction cable drive pulley and a traction cable return pulley, the traction cable being continuously driven around the drive and return pulleys.

[0019] The transport apparatus further comprises a pulley for deflecting the towing cable and said at least one cleaning device is connected to the towing cable by a fixing clamp configured to pass at the level of the drive, deflect and return pulleys.

[0020] This provides automated cleaning means, i.e., ones that do not require human intervention to move the cleaning devices from one panel to another. Furthermore, the system is particularly suitable for a floating power plant in which the height of the solar panels can be variable.

[0021] The system may include a jib carrying a rotating element for supporting and guiding the towing cable.

[0022] The boom can be retracted. This reduces the amount of shadow cast by the boom when the transport device is not in use.

[0023] The at least one cleaning device may comprise a motorized cleaning element and a drive unit configured to operatively drive the motorized cleaning element.

[0024] According to one embodiment, the drive unit is electric and said at least one cleaning device comprises an electrical energy storage unit coupled to the drive unit.

[0025] According to another embodiment, the drive unit is electric and the transport apparatus comprises an electrical energy generator coupled to the drive unit via electric wires located along the towing cable.

[0026] According to another aspect, a solar panel power station is provided comprising a cleaning system as defined above.

[0027] According to one embodiment, each solar panel comprises a floating anchoring element.

[0028] Advantageously, each solar panel is a photovoltaic panel.

[0029] According to another embodiment, each solar panel comprises a ground anchoring element.

[0030] According to yet another aspect, there is provided a cleaning method for a solar panel power plant.

[0031] The method comprises pulling at least one cleaning device of at least one solar panel by a towing cable. BRIEF DESCRIPTION OF THE FIGURES

[0032] Other advantages and characteristics will emerge more clearly from the following description of embodiments and implementations of the invention given as non-limiting examples and represented in the appended drawings, in which: There figure 1 , schematically illustrates a side view of an embodiment of a cleaning system for a solar panel power plant; The figure 2, schematically illustrates a top view of one embodiment of the cleaning system; The figure 3 , schematically illustrates a top view of another embodiment of the cleaning system; The figures 4 to 8 , schematically illustrate perspective views of different embodiments of a cleaning device; The figure 9 , schematically illustrates a side view of a jib in the deployed position; The figure 10 , schematically illustrates a side view of a gallows in an intermediate position; The figure 11 , schematically illustrates a side view of one embodiment of a jib in the retracted position; The figure 12 , schematically illustrates a side view of another embodiment of a jib in the retracted position; The figure 13 , schematically illustrates a top view of another embodiment of a cleaning system; The figure 14, schematically illustrates a sectional view of one embodiment of the cleaning system; The figure 15 , schematically illustrates a sectional view of another embodiment of the cleaning system; The figure 16 , schematically illustrates a perspective view of the embodiment illustrated in figure 15 ; There figure 17 , schematically illustrates another embodiment of the cleaning system; The figure 18 , schematically illustrates a sectional view of an embodiment of a towing cable; The figure 19 , schematically illustrates a sectional view of an embodiment of a fixing clamp; The figure 20 , schematically illustrates a sectional view of another embodiment of a fixing clamp; The figures 21 to 23 , schematically illustrate side views of different positions of a gallows; The figure 24, schematically illustrates a perspective view of another embodiment of the cleaning system; and The figure 25 , schematically illustrates a front view of the embodiment illustrated in figure 24 . DETAILED DESCRIPTION OF THE INVENTION

[0033] On the figures 1 to 3 , a power station 1 with solar panels 2 is shown. The solar panels 2 may be thermal panels, i.e. panels comprising solar thermal collectors to transform part of the solar radiation into heat. Preferably, the solar panels 2 are photovoltaic panels, also called photovoltaic modules, i.e. they comprise photovoltaic cells to convert part of the solar radiation into electrical energy. Generally, the power station 1 comprises several solar panels 2. Advantageously, the solar panels 2 are distributed over several rows 3a to 3d. On the figure 2, at least four rows 3a to 3d have been shown as an example. Each row 3a to 3d may comprise several solar panels 2, preferably aligned. On the figure 2 , each row 3a to 3d comprises at least four solar panels 2. A solar panel 2 has a general shape of a parallelepiped. Furthermore, each solar panel 2 comprises at least one support 90, 91 configured to support the solar panel 2. The supports 90, 91 can be anchored or placed on the ground, and in this case the power station 1 is said to be “terrestrial”. Alternatively, the supports 90, 91 are floats intended to be placed on water, and in this case the power station 1 is said to be “floating”. It is also said that the supports 90, 91 are floating.

[0034] In particular, the power plant 1 comprises a cleaning system 4 configured to clean the solar panels 2. The cleaning system 4 comprises at least one cleaning device 5 capable of cleaning at least one solar panel 2. More particularly, the cleaning system 4 comprises a transport apparatus 6 configured to transport the cleaning devices 5 by tractor cable 7. On the figure 1 , a single cleaning device 5 has been shown for simplification purposes. The transport apparatus 6 makes it possible to tow the cleaning devices 5 and facilitates the transfer of the cleaning devices 5 from one solar panel 2 to another.

[0035] The transport apparatus 6 comprises the traction cable 7, a drive pulley 8, at least one return pulley 9, a motor 10 and a tensioning device 11 for the traction cable 7. The drive pulley 8 is configured to drive the traction cable 7 when it is rotated about an axis of rotation A. The motor 10 is coupled to the drive pulley 8 and allows it to be rotated about the axis of rotation A. The return pulley 9 allows, with the aid of the tensioning device 11, to tension the traction cable 7 to facilitate the movement of the traction cable 7. The tensioning device 11 comprises a support element 12 and a hydraulic cylinder 13 which connects the support element 12 to an axis of rotation B of the return pulley 9. The hydraulic cylinder 13 can adapt the tension that it exerts on the axis of rotation. rotation B, and therefore allows the tension of the towing cable 7 to be varied.The towing cable 7 may be made of steel, for example from strands gathered in the shape of a helix. The towing cable 7 may also be made of nylon, with one strand or several strands gathered in the shape of a helix and forming strands. Alternatively, the towing cable 7 may be covered with a plastic sheath. Furthermore, the motor 10 is mounted on a motor frame 14 and the rotation axis B of the return pulley 9 is mounted on a support frame 15. In one embodiment, the cleaning system 4 comprises a return pulley 9 and a drive pulley 8. Thus, at least one row 3a of solar panels 2 can be cleaned. The motor 10 can rotate the drive pulley 8 in a single direction of rotation. In this case, the cleaning devices 5 travel through the loop formed by the towing cable 7 always in the same direction.Alternatively, the motor 10 can reverse the direction of rotation of the drive pulley 8, and the cleaning devices 5 can travel the loop in either direction. In this case, the transport apparatus 6 is said to operate back and forth.

[0036] According to the invention, the cleaning system 4 comprises one or more deflection pulleys 16 for deflecting the path of the towing cable 7. The deflection pulleys 16 make it possible to clean several rows of solar panels 2. Each deflection pulley 16 is also mounted to rotate about an axis of rotation C. The axes of rotation C of the deflection pulleys 16 are respectively mounted on support frames not shown for the sake of simplification. Furthermore, in the case of a land-based power plant 1, the motor 14 and support 15 frames are anchoring elements fixed to the ground. In the case of a floating power plant 1, the motor 14 and support 15 frames of the deflection 16 and return 9 pulleys are floats placed on the water and equipped with anchoring systems 92 to hold the frames 14, 15 in position. Alternatively, the supports 90, 91 of the solar panels 2 can also be provided with an anchoring system 92.

[0037] On the figures 2 And 3 , several solar panels 2 are shown distributed over several rows 3a to 3d. Each row 3a, 3d comprises several solar panels 2. Preferably, the solar panels 2 of a row 3a to 3d are aligned, that is to say they are arranged next to each other successively along a direction D, E, called the alignment direction. For example, as illustrated in the figure 3, the solar panels 2 of a first row 3a are aligned along the first direction D. The solar panels 2 of a second row 3b are aligned along the second direction E. Preferably, the rows 3a to 3d are arranged parallel, in other words the rows 3a to 3d are said to be parallel to each other. That is to say that the alignment directions D, E of the solar panels 2 are parallel. All of the solar panels 2 form a series. The series comprises the solar panels 2 of the different rows 3a to 3d. The transport apparatus 6 is configured so that the traction cable 7 is arranged along the different rows 3a to 3d of solar panels 2. The cleaning system 4 may comprise several deflection pulleys 16. Preferably, a deflection pulley 16 is located at the end of a row 3a to 3d. Preferably, a deflection pulley 16 is located at the end of two successive rows 3a to 3d.Each time a deflection pulley 16 passes, the towing cable 7 changes direction. A deflection pulley 16 therefore allows the towing cable 7 to pass from one row 3a to 3d to the other. In particular, the towing cable 7 is positioned so that it connects the drive pulley 8 to the return pulley 9 by passing in contact with each deflection pulley 16. More particularly, the drive 8, return 9 and deflection 16 pulleys are configured so as to position the towing cable 7 so that it passes at the level of, that is to say above, each solar panel 2. In other words, the towing cable 7 extends along the different rows 3a to 3d, that is to say along the different alignment directions D, E. The position of the towing cable 7 allows a change of rows 3a, 3d for the cleaning device 5.Thus, when the towing cable 7 is animated in movement, it makes it possible to tow a cleaning device 5 from one solar panel 2 to another, and more particularly from one row 3a to 3d to another to clean several rows 3a to 3d of solar panels 2. By several rows 3a to 3d, is meant the fact that several solar panels 2 belonging respectively to several rows 3a to 3d, are arranged next to each other in a direction perpendicular to the alignment directions D, E. In other words, the deflection pulleys 16 allow a change of direction D, E of the towing cable 7 to allow the cleaning device 5 to change rows 3a to 3d. The deflection pulleys 16 make it possible to clean a series of solar panels of different rows 3a to 3d, preferably parallel. Thus, it is possible to clean several rows 3a to 3d of solar panels 2.

[0038] Such a transport apparatus 6 makes it possible to use a remote motor 10 to drive the cleaning devices 5. That is to say, the motor 10 is located at a distance from the cleaning devices 5. Furthermore, thanks to the transport apparatus 6, a single motor 10 is used to move the cleaning devices 5. Maintenance of the cleaning system 4 is therefore simpler. Furthermore, the cleaning devices 5 are not necessarily equipped with wheels, drive motors, or electronic equipment to control their positioning and to control obstacles. The cleaning devices 5 can therefore be lighter and simpler to produce.

[0039] According to an embodiment illustrated in the figure 2 , the towing cable 7 forms a continuous loop and passes around the drive pulleys 8, return pulleys 9 and deflection pulleys 16. In other words, the towing cable 7 is in contact with each of the pulleys 8, 9, 16. On the figure 2, five deflection pulleys 16 are shown by way of example. When the drive pulley 8 is rotated, it drives the traction cable 7 in translation in a first direction, represented by the reference D, in particular from the drive pulley 8 towards a first deflection pulley 16. In addition, the traction cable 7 is driven in translation in a second direction E opposite to the first direction D, in particular between the first deflection pulley 16 and a second deflection pulley. Each time a deflection pulley passes, the traction cable 7 changes direction. The cleaning system 4 may also comprise at least one platform 95, 96 as a starting and / or arrival point for the cleaning devices 5. On the figure 2 , platform 95 corresponds to the starting and arrival point of devices 5.

[0040] On the figure 3, another embodiment of the central unit 1 is shown, in which the traction cable 7 is wound around the drive pulley 8. In this case, the traction cable 7 does not form a continuous loop but a single strand which is wound and unwound, using the drive pulley 8, to change the direction of the first and second directions D, E. In the case of a drive system 4 having a single-strand traction cable 7, the motor 10 can reverse the direction of rotation of the drive pulley 8, and the transport apparatus 6 operates back and forth. Furthermore, the cleaning system 4 may comprise a departure dock 95 for the devices and an arrival dock 96 for the devices 5.

[0041] Generally, the towing cable 7 is an aerial cable, that is to say that the towing cable 7 is held in the air. To improve the holding in the air of the towing cable 7, the cleaning system 4 may comprise one or more jibs 17. A jib 17 is a support element for the towing cable 7. In particular, a jib 17 carries one or more rotating elements 18, 80. A rotating element 18, 80 is an element rotatably mounted on the jib 17, configured to support and guide the towing cable 7. For example, the rotating elements 18, 80 are rotating rollers, that is to say cylinders with a circular section and provided with a groove to facilitate the guiding of the towing cable 7. When the towing cable 7 is in motion, the rotating rollers 18 are rotated on the jib 17 which carries them. Preferably, each solar panel 2 is equipped with a bracket 17. A bracket 17 may be mounted on an edge of a solar panel 2.More particularly, each bracket 17 is mounted at one end of a solar panel 2.

[0042] On the figures 4 to 8, embodiments of a cleaning device 5 have been shown. Generally, the cleaning device 5 comprises a cleaning element 20, a pole 21 connected to the cleaning element 20 and a fixing means 22 connected to the pole 21. The different parts 20, 21 and 22 of the cleaning device 5 are mechanically connected to each other. The pole 21 is an elongated element, for example a cylindrical element, preferably a rod. Advantageously, the pole 21 may comprise a threaded rod and a tapped tube intended to cooperate with the threaded rod. Thus, the pole 21 may have a constant length adjustable as a function of a distance between the traction cable 7 and the solar panel 2. The pole 21 may also be telescopic or comprise a winder. Thus, the pole 21 may have a variable length to adapt to differences in distance between the traction cable 7 and the solar panels 2.The pole 21 may further comprise a damping system, for example a hydraulic or pneumatic cylinder to avoid damaging the solar panels 2 when the cleaning devices 5 are in contact with the solar panels 2. The fixing means 22 is configured to hook the pole 21 to the towing cable 7. The fixing means 22 is preferably located at one end of the pole 21. According to the invention, the fixing means 22 comprises a fixing clamp 22a. Generally, the fixing clamp 22a is configured to pass at the level of the drive 8, return 9 and deflection 16 pulleys.

[0043] When the towing cable 7 is moved, the cleaning device(s) 5 attached to the towing cable 7 are driven. The movement of the cleaning device(s) 5 makes it possible to clean the surface of the solar panels 2.

[0044] The cleaning element 20 may be movable. For example, as shown in figure 4, the cleaning element 20 comprises a frame 23 on which is mounted a rotating brush 24, advantageously several rotating brushes. The rotating brush 24 can be made with synthetic fibers or animal hair. The pole 21 can be mounted on the frame 23 by means of a joint 25. Thus, when the cleaning device 5 is moved into contact with a solar panel 2, the rotating brushes 24 are rotated by friction and can remove the dirt present on the surface of the solar panel 2. Alternatively, the cleaning device 5 can comprise a drive unit 29, for example an electric motor, configured to drive the rotating brush 24 into operation in order to improve cleaning. According to another embodiment, illustrated in figure 6, the cleaning device 5 comprises a scraper 26 mounted on the frame 23. The scraper 26 can be a plate made of rubber, silicone, or flexible plastic.

[0045] The cleaning element 20 may further be motorized, as illustrated in the figures 5 , 7 and 8 . In this case, the cleaning device 5 comprises a drive unit 29, for example an electric motor, configured to drive the cleaning element 20 into operation. On the Figure 5 , an embodiment is shown in which the cleaning element 20 comprises one or more rotating pucks 27. The rotating puck(s) 27 are driven by one or more toothed wheels 28. The rotating pucks 27 can be oriented parallel to the frame 23. In this embodiment, the drive unit 29 drives the toothed wheels 28 in rotation, and therefore the rotating pucks 27. As a variant, illustrated in figure 7, the cleaning device 5 comprises one or more nozzles 30 connected to one or more containers 31, and controlled by the drive unit 29. The containers 31 may contain a liquid or a gas. The nozzles 30 are configured to produce a jet of liquid or gas contained in the container(s) 31. According to yet another embodiment, illustrated in figure 8 , the cleaning element 20 comprises one or more vacuum cleaners 32 operated by the drive unit 29 to suck up the dirt.

[0046] On the figures 11 to 13, embodiments of a retractable bracket 17 have been shown. That is to say, a bracket 17 which can occupy different positions S, T, V relative to the solar panel 2 on which it is mounted. Such a bracket 17 makes it possible to limit the parasitic shadows projected on the solar panels 2. More particularly, the bracket 17 can occupy a deployed position S, called functional, in which it ensures the support and guidance of the traction cable 7, and a retracted position V, called rest, in which the bracket 17 is placed partly under the solar panel 2. Between the deployed position S and the retracted position V, the bracket 17 can occupy one or more intermediate positions T. In the deployed position S, the bracket 17 can generate a shadow on the solar panel 2, and limit the energy yield of the latter. In the retracted position V, the boom 17 is placed partly under the solar panel 2 so as to no longer generate shade.

[0047] The bracket 17 comprises an upper part 40 and a lower part 41. The upper part 40 comprises a first end 42 where the rotating rollers 18, 80 are mounted and a second opposite end 43 connected to the lower part 41. The solar panel 2 comprises an edge 44 on which the bracket 17 is connected. In addition, the bracket 17 comprises a piston 45, a pivot axis 46, a connecting element 47 and an actuator connection 48. The lower part 41 is integrated in the piston 45. The piston 45 is connected to the pivot axis 46. The pivot axis 46 is housed within the connecting element 47. The actuator connection 48 connects the lower part 41 to an actuator 49. The connecting element 47 is for example a stirrup, it is connected to the edge 44 of the solar panel 2, for example by a screws or using pliers or a clamp.Advantageously, the connecting element 47 is partly open to allow pivoting of the pivot axis 46 relative to an axis parallel to the edge 44. According to yet another advantage, the bracket 17 comprises a torsion spring 50 mounted on the pivot axis 46. One of the ends of the spring 50 is fixed on the pivot axis 46 and another end is fixed on the connecting element 47 so as to constrain the bracket 17 in the deployed position S. The piston 45 comprises a cylinder 51 and an elastic system 52, for example a helical spring or a gas. The actuator connection 48 may be a flexible element, for example a cable, or a rigid element, such as a bar. When it is desired to retract the boom 17, the actuator 49 exerts tension on the connecting element 48, the boom 17 pivots around the pivot axis 46 while bearing on the connecting element 47 and the boom 17 passes from the deployed position S to an intermediate position T, illustrated in the . figure 10 The tension exerted on the actuator link 48 causes the arm 17 to tilt around the pivot axis 46. On the figure 11 , the bracket 17 occupies its retracted position V, and the tension on the actuator connection 48 causes a compression of the piston 45, that is to say a sliding of the lower part 41 within the cylinder 51. The sliding causes a translation of the lower 41 and upper 40 parts of the bracket 17 along the solar panel 2. On the figure 12 , the stem 17 occupies its retracted position V and the piston 45 is compressed. When it is desired to deploy the stem 17, the actuator 49 releases the tension on the actuator connection 48, and the piston 45 decompresses. When the piston 45 decompresses, the lower part 41 of the stem 17 slides, under the effect of the elastic system 52, towards the outside of the piston 45. Then, due to the spring 50, the stem 17 returns to its deployed position S. On the figure 13, an embodiment is shown in which the actuator 49 is connected to several brackets 17 via several respective actuator links 48.

[0048] Advantageously, when the jib(s) 17 are retracted, the tension exerted on the towing cable 7 is also reduced. In particular, the tension is reduced using the tensioning device 11 which can vary the tension exerted on the towing cable 7. Thus, by reducing the tension exerted on the towing cable 7, the jibs 17 can be retracted while maintaining the towing cable 7 in contact with the drive 8, return 9 and deflection 16 pulleys. Furthermore, when it is desired to put the cleaning system 4 into operation again, the jibs 17 are deployed, then the tension exerted on the towing cable 7 is increased using the tensioning device 11.

[0049] In the case where the cleaning element 20 is motorized using an electric drive unit 29, the cleaning system 4 comprises means for supplying electrical energy to the electric drive unit 29 so as to be able to power it. The supply means may be an electrical energy storage unit, for example a battery, preferably a lithium type battery. In this case, each cleaning device 5 comprises an electrical energy storage unit, not shown for the sake of simplification, mounted on the chassis 23 of the device 5. Alternatively, as illustrated in the figure 17, the supply means are an electrical energy generator 60 coupled to the electric drive unit 29 via electrical wires 61, 62 located along the towing cable 7. The generator 60 can be located on the engine chassis 14, to further power the engine 10 of the transport apparatus 6. The generator 60 can correspond to the public network located remotely and connected, by electrical cables not shown for the sake of simplification, to the electrical wires 61, 62, and to the engine 10.

[0050] The drive units 29 of the cleaning devices 5 are, for example, motors operating with single-phase 12 Volt DC. This voltage level is lower than 25 Volt AC, which is considered to be a danger threshold for humans in a humid environment.

[0051] As illustrated on the figures 17 And 18, the towing cable 7 supports the electrical wires 61, 62 and the transport apparatus 6 comprises connection means 63, 64 for connecting the generator 60 to the electrical wires 61, 62 respectively. In particular, a first connection means 63 comprises a first connector 65 in contact with a first electrical wire 62. The first connector 65 is connected to a first terminal 66 of the generator 60 via a first damping tensioner 67. The second connection means 64 comprises a second connector 68 in contact with the second electrical wire 61. The second connector 68 is connected to a second terminal 69 of the generator 60 via a second damping tensioner 70.

[0052] The first and second connectors 65, 68 may be pads that rub on the electrical wires 61, 62. The first and second damping tensioners 67, 70 may be pneumatic cylinders, or a compression spring. The first and second damping tensioners 67, 70 maintain contact between the connectors 65, 68 and the electrical wires 61, 62, when the towing cable 7 swings up and down, for example in windy conditions.

[0053] On the figure 17 , a cleaning device 5 is also shown comprising an electrical drive unit 29 connected to the electrical wires 61, 62 by respective connection wires 71, 72. The connection wires 71, 72 extend along the pole 21 of the cleaning device 5.

[0054] On the figure 18, the towing cable 7 is shown wrapped in an insulating part 73. The electrical wires 61, 62 are housed partly within the insulating part 73 so as to be insulated from each other and from the towing cable 7. The electrical wires 61, 62 are located along the towing cable 7. In particular, the electrical wires 61, 62 have a visible external part, i.e. not insulated, intended to be in contact with the connectors 65, 68 of the connection means 63, 64.

[0055] On the figures 14 to 16 two embodiments of a jib 17 and a pole 21 of the cleaning device 5 adapted to the jib 17 are shown. On the figure 14, the jib 17 comprises one or more rotating support rollers 18, located under the towing cable 7, intended to support and guide the towing cable 7. In addition, the jib 17 comprises rotating compression rollers 80, located on the towing cable 7, intended to press on the towing cable 7 to prevent it from coming out of the rotating support rollers 18 and leaving the jib 17. In this case, the pole 21 extends laterally relative to the fixing means 22 so as to be able to pass next to the rotating support rollers 18 while allowing the fixing means 22 to pass over the rotating support rollers 18 when the cleaning device 5 passes at the jib 17. According to yet another advantage, rotating support rollers 18 can be placed at each of the drive 8, return 9 and deflection 16 pulleys, to prevent the towing cable 7 from coming out pulleys 8, 9, 16 during an operation to retract the jibs 17.More particularly, a rotating support roller 18 can be placed at the inlet of each pulley 8, 9, 16, i.e. at the level where the traction cable 7 comes into contact with the pulley 8, 9, 16, and also at the outlet of each pulley 8, 9, 16, i.e. at the level where the traction cable 7 leaves the pulley 8, 9, 16 with which it is no longer in contact.

[0056] On the figures 15 , 16, the bracket 17 comprises one or more rotating support rollers 18, located under the traction cable 7, intended to support and guide the traction cable 7. In addition, the bracket 17 comprises rotating compression rollers 80, located on the traction cable 7, intended to press on the traction cable 7 to prevent it from coming out of the rotating support rollers 18 and leaving the bracket 17. In particular, each rotating support roller 18 comprises two half-rotary rollers 18a, 18b placed opposite each other and spaced from each other by a gap 81 allowing passage of the pole 21 of the cleaning device 5. The gap 81 is further provided so that the traction cable 7 remains in contact with the half-rotary rollers 18a, 18b after the passage of the pole 21.In this case, the pole 21 extends below the fixing means 22, in particular directly above the traction cable 7, so as to be able to pass between the rotating half-rollers 18a, 18b while allowing the fixing means 22 to pass over the rotating half-rollers 18a, 18b when the cleaning device 5 passes at the level of the bracket 17.

[0057] On the figure 16 , a bracket 17 adapted to the poles 21 extending below the fixing means 2 is shown. Such a bracket 17 also makes it possible to trap the traction cable 7 while avoiding losing the traction cable 7 during a retraction operation of the brackets 17. Advantageously, it is also possible to place rotating half-rollers 18a, 18b at the input and output of each of the drive pulleys 8, return pulleys 9 and deflection pulleys 16, to prevent the traction cable 7 from coming out of the pulleys 8, 9, 16 during a retraction operation of the brackets 17.

[0058] On the figures 19 and 20, two embodiments of a fixing clamp 22a are shown. Generally, the fixing clamp 22a comprises two jaws 22b, 22c which are shaped to grip the traction cable 7. In particular, at least one jaw 22b, 22c is movable relative to the other. For example, the upper jaw 22b is movable relative to the lower jaw 22c which is mechanically connected to the pole 21. The upper jaw 22b opens to place the fixing clamp 22a around the traction cable 7, then the upper jaw 22b is closed while keeping it in contact with the lower jaw 22c, for example by means of a fixing bolt, i.e. a screw cooperating with a nut, to keep the fixing clamp 22a attached to the traction cable 7. On the figure 19 , an embodiment is shown in which the pole 21 extends laterally relative to the fixing clamp 22a. On the figure 20, another embodiment is shown in which the pole 21 extends below the fixing clamp 22a. Also shown in the figures 19 and 20 , two embodiments of the pole 21 and the fixing clamp 22a adapted to a cleaning device 5 having a motorized cleaning element 20. In this case, the cleaning device 5 comprises two connection wires 71, 72 located along the pole 21. Each connection wire 71, 72 is surrounded by an insulating sheath to insulate the wires from each other and from the pole 21. Each connection wire 71, 72 comprises a first end 74, 75 connected to a terminal of the drive unit 29 of the cleaning device 5, and a second end 76, 77 shaped to be brought into contact with the respective electrical wires 61, 62 of the transport apparatus 6. Advantageously, each second end 76, 77 can be a conductive plate to promote electrical contact with the electrical wires 61, 62.

[0059] On the figures 21 to 22 , another embodiment of a power station 1 with solar panels 2 has been shown. In this embodiment, the solar panels 2 are inclined relative to a line Y passing through the supports 90, 91 of the solar panels 2. In other words, the solar panels 2 form a non-zero angle of less than 90° with the line Y passing through the supports 90, 91.

[0060] On the figures 21 to 22 the different positions of a retractable 17 gallows are also shown. On the figure 21 , the gallows 17 occupies a deployed position S. On the figure 22 , the stem 17 occupies a retracted position V in which the piston 45 is decompressed. On the figure 23 , the stem 17 occupies a retracted position V in which the piston 45 is compressed.

[0061] On the figures 24 and 25another embodiment of a power station 1 with solar panels 2 has also been shown. In this other embodiment, the solar panels 2 are inclined relative to the lines Y passing through their respective supports 90, 91. The cleaning device 5 comprises a pole 21 inclined relative to its frame 23. Advantageously, the inclination of the pole 21 is equal to the inclination of the solar panels 2. A bracket 17 has also been shown having two rotating half-rollers 18a, 18b placed opposite each other and spaced from each other by a gap 81 allowing passage of the pole 21 of the cleaning device 5. In this case, the pole 21 extends below the fixing clamp 22a.

[0062] A cleaning method for a power plant 1 with solar panels 2 can be implemented by the cleaning system 4 which has just been described.

Claims

1. Cleaning system for solar power plant (2), comprising at least one device (5) for cleaning at least one solar panel (2), an appliance (6) for transporting said at least one cleaning device (5) by hoisting cable (7), the transport appliance (6) comprising a pulley (8) for driving the hoisting cable (7), characterised in that the transport appliance (6) comprises a pulley (9) for returning the hoisting cable (7), the hoisting cable (7) being continuously driven around the drive (8) and return (9) pulleys, and in that the transport appliance (6) further comprises a pulley (16) for deviating the hoisting cable (7) and said at least one cleaning device (5) is connected to the hoisting cable (7) by a fixing clamp (22a) configured to pass at the drive (8), deviation (16) and return (9) pulleys.

2. System according to claim 1, comprising a stem (17) carrying a rotary element (18, 18a, 18b) for supporting and guiding the hoisting cable (7).

3. System according to claim 2, wherein the stem (17) is retractable.

4. System according to any one of claims 1 to 3, wherein said at least one cleaning device (5) comprises a motorised cleaning element (20) and a drive unit (29) configured to drive the motorised cleaning element (20) in operation.

5. System according to claim 4, wherein the drive unit (29) is electric and said at least one cleaning device (5) comprises an electric energy storage unit coupled with the drive unit (29).

6. System according to claim 4, wherein the drive unit (29) is electric and the transport appliance (6) comprises an electric energy generator (60) coupled with the drive unit (29) through electric wires (61, 62) located along the hoisting cable (7).

7. Solar power plant (2), characterised in that it comprises a cleaning system (4) according to any one of claims 1 to 6.

8. Power plant according to claim 7, wherein each solar panel (2) comprises a floating support (90, 91).

9. Power plant according to claim 8, wherein each solar panel (2) is a photovoltaic panel.

10. Power plant according to claim 7, wherein each solar panel (2) comprises a support (90, 91) anchored to the ground.

11. Cleaning method for a solar power plant (2), characterised in that it comprises a hoisting of at least one cleaning device (5) of at least one solar panel (2) by a hoisting cable (7), while using a cleaning system according to any one of claims 1 to 6.