PROTECTING AND CLEANING SOLAR PANELS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62/963,743, filed on January 21, 2020, entitled “METHOD AND SYSTEM FOR PROTECTING AND CLEANING SOLAR PANELS,” the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

TECHNICAL FIELD

[0002] Embodiments of the subject matter disclosed herein generally relate to a system and method for cleaning a solar panel, and more particularly, to a system that covers the solar panel with a removable transparent film for preventing particulates from attaching to the active surface of the solar panel.

DISCUSSION OF THE BACKGROUND

[0003] With the growing global concern from fossil fuels usage and sustainability, renewable energy is evolving rapidly worldwide. Electricity generation is vital to modern economies and life. Currently, power generation accounts for almost 50% of the global greenhouse gas emissions. Decarbonizing the power sector, while meeting the growing electricity demand, is a major challenge for decades to come. Solar power using photovoltaics plays a critical role in addressing the energy challenge and expected to become the world's largest source of electricity.

[0004] A solar photovoltaics (PV) cell 102, as illustrated in Figure 1, is a device that converts sunlight into electric current. The PV cells 102 are typically arranged in arrays of modules (panels) 100 that are wired together. The PV panels are currently used at both residential and industrial scales. The electricity production from solar systems depends on the availability of sunlight (climate) and the availability of the land area to host the solar panels.

[0005] Deserts are appealing locations for solar power plants for their availability of sunlight and space. Deserts located in low latitudes, such as those in the Middle East, are classified as the sunniest locations on earth. While deserts are appealing targets for solar power plants, they typically exhibit a harsh climate, which is associated with high air pollution from dust and sand storms (i.e. , particulates), and excessive heat ranges. Dust and other material accumulations 104 on the top of the solar-panel surfaces (hard shading) can significantly jeopardize the efficiency of the solar PV system 100. For instance, a sand storm can cause an immediate 60% reduction in electricity generation from the hard-shaded solar panels. Another challenge related to the desert climate is the excessive heat and temperature that can cause accelerated degradation of the solar PV material. As a result, the PV modules will be less durable, and their lifecycle will be shorter compared to those used in less severe climates. [0006] Many solutions have been proposed to address the solar-panel cleaning problem. The current methods can be classified into three main categories: [0007] Manual cleaning: manual cleaning is labor intense, costly, and inefficient.

[0008] Mechanical cleaning: mechanical cleaning, is typically an automated process that uses robots 110 with brushes 112, see Figure 1, to wipe the panel surfaces with and without water. Mechanical cleaning that uses robots and brushes can be effective; however, these robots may cause mechanical degradation and damage to the panel surfaces.

[0009] Self-cleaning: self-cleaning methods do not require any mobile devices or robots. These methods include passive self-cleaning methods and active self cleaning technologies. With passive self-cleaning, the panel surfaces are coated with chemicals to change the surface tension to repel dirt. Wth active self-cleaning technologies, dust is removed using electrostatic or ultrasonic devices. These technologies are still expensive, immature, and have limitations in terms of the size and amount of solid contaminates.

[0010] Thus, there is a need for a new system and method to protect the solar panels from various particulates, without experiencing the problems noted above.

BRIEF SUMMARY OF THE INVENTION

[0011] According to an embodiment, there is a protection system for protecting a solar panel. The protection system includes a rail system extending along the solar panel, a roll-carrier configured to move along the rail system, wherein the roll-carrier holds first and second protective films, and a local controller configured to control a movement of the roll-carrier. The roll-carrier is configured to simultaneously (1) supply a clean part of the first protective film over a surface of the solar panel, and (2) remove a dirty part of the second protective film from the surface of the solar panel.

[0012] According to another embodiment, there is a method for protecting a solar panel from particulates, and the method includes loading first and second protective films into a roll-carrier, and driving the roll-carrier along a rail system, which extends along the solar panel, to simultaneously remove a dirty part of the second protective film and to distribute a clean part of the first protective film on a surface of the solar panel.

[0013] According to still another embodiment, there is a roll-carrier for protecting a solar panel, and the roll-carrier includes a frame configured to move along a rail system, first and second clean film rolls attached to the frame, first and second protective films wrapped around the first and second clean film rolls, respectively, a motor configured to translate the frame and to independently rotate the first and second clean film rolls, and a local controller configured to control the translation of the roll-carrier and the rotation of the first and second clean film rolls. The roll-carrier is configured to simultaneously (1) supply a clean part of the first protective film over a surface of the solar panel, and (2) remove a dirty part of the second protective film from the surface of the solar panel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0015] Figure 1 illustrates a traditional brush system for cleaning an active surface of a solar panel;

[0016] Figure 2 illustrates a new brushless system for protecting an active surface of a solar panel from particulates;

[0017] Figure 3 illustrates a roll-carrier that is part of the new brushless system;

[0018] Figure 4 illustrates a variant of the roll-carrier;

[0019] Figures 5A to 5C illustrate the new brushless system at various points during a process of removing a dirty film and providing a clean film on the active surface of the solar panel;

[0020] Figure 6 is a flowchart of a method for protecting a solar panel with the new brushless system;

[0021] Figures 7 A to 7C illustrate the process of removing the dirty protecting film and the supply of the clean protecting film on the solar panel; and [0022] Figure 8 is a flowchart of another method for protecting the solar panel with the new brushless system. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention.

Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a system that protects a solar panel with a transparent film, which can be changed when the film is too dirty.

However, the embodiments to be discussed next are not limited to applying a protection film on a solar panel, but may be applied to other devices that need to be protected from dust and similar materials.

[0024] Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0025] According to an embodiment, there is a system that is configured to meter a protective and transparent, clean film over a solar panel array while at the same time recovering another protective and transparent, dirty film, from the same solar panel array. The system may be an automated system that automatically determines when the protective films need to be distributed/collected, and the system automatically performs these two operations simultaneously. The protective films may be self-adhesive so that they directly adhere to the surface of the solar panels and prevent most if not all the particulates from reaching the active surface of the solar panel. Because the protective films adhere directly to the active surface of the solar panels, there is no danger that wind will remove the films from the solar panel. Also, the adherence between the protective films and the active surface of the solar panels not only prevents the particulates from reaching the active surface, but also offers protection against the ambient heat when the solar panel is located in a desertic zone.

[0026] One or more advantages of such a system is the lack of mechanical brushes or a cleaning fluid, which may damage the active surface of the solar panel. Further, by offering protection from heat and harsh weather, the protective films may extend the lifecycle of the solar panels, and may also boost their efficiency. The process of maintaining the solar panels clean may be fully automatized, thus reducing the need to have dedicated personnel for cleaning the solar panels. In one application, the protective films installation/replacement is simultaneous and therefore, the solar panels are not exposed to the ambient and, as a result, they stay contaminate-free. In one application, the protection system requires simple mechanics, e.g., one or more motors to move a roll-carrier and to rotate the rolls holding the protective films. If necessary, the process of applying/replacing the protective films can be done manually, without the need for any motor. The protection system can be installed in existing solar plants as well as in new ones. The protection system can be installed at the industrial scale for panel arrays that extend for dozens of meters as well as at the residential scale, where the panels extend for a few meters.

[0027] The protective system is now discussed in more detail with regard to Figure 2. The protective system 200 includes a roll-carrier 210 that is configured to move along a rail system 220, which is positioned along the solar panels 102, as shown in Figure 2. Note that Figure 2 shows plural solar panels 102 extending for a length L, which may be in the order of meters to hundreds of meters. The rail system 220 includes at least one rail 222, preferably two, 222 and 224, that are parallel to each other. The rails 222 and 224 are supported by legs 226, which are grounded, and which are sized so that the panels 102 may be oriented to be horizontal or tilted relative to a horizontal plane. The protective system 200 discussed herein is configured to work even if the solar panels are disposed in a vertical plane relative to the horizontal plane.

[0028] A first dirty protective film roll 230 is provided at a first end 220A of the rail system 220 and a second dirty protective film roll 232 is provided at a second end 220B of the rail system 220. In one embodiment, each of the first and second dirty protective film rolls are attached to the rails 222 and 224. A length W of the rolls may be in the order of meters, for example, between 1 and 4 meters. The first dirty protective film roll 230 is configured to hold an end of a first clean protective film 231 while the second dirty protective film roll 232 is configured to hold an end of a second clean protective film 233. Each film 231 and 233 is made of a transparent material, which might have an adhesive surface. The films are rolled on their respective rolls and they are not in contact with each other. Each film extends from its corresponding roll hold by the rail system to another corresponding roll hold by the roll-carrier 210. This means that four different rolls are used to hold the two films 231 and 233.

[0029] In this respect, the roll-carrier 210, which is shown in more detail in Figure 3, has first and second clean film rolls 331 and 333, each configured to hold a corresponding clean film 231 or 233. The roll-carrier 210 is attached with corresponding wheel assemblies 302 or equivalent mechanisms to the two rails 222 and 224. One or more wheel assemblies 302 may be used to hold the roll-carrier to each of the two rails. For simplicity, the embodiment illustrated in Figure 3 shows the roll-carrier having two wheel assemblies 302 for each rail. A wheel assembly 302 may include one or more wheels. For example, as also shown in Figure 3, a wheel assembly 302 may have two wheels 304 and 306, which are configured to sandwich the rail 224, for being able to hold onto the rail. Other mechanisms may be used for achieving the same results.

[0030] The roll-carrier 210 may also include a motor 310 that may serve multiple purposes. For example, in one application, the motor 310 is connected to the wheel assemblies 302 for actuating their wheels, to translate the roll-carrier 210 along the rails 222 and 224, in either direction. The motor 310 may be an electrical motor that is provided with energy from the solar panels 102, or from a local power supply 312, e.g., a battery, or with energy supplied through the rails 222 and 224 from an external power source 314, which is electrically connected to the two rails. The external power source 314 may be a fuel cell, the solar panel 102, the power grid, etc.

[0031] The roll-carrier 210 has a frame 320 that is configured to hold the wheel assembly 302, the motor 310, and the power supply 312. In addition, the frame 320 is configured to hold the first and second rolls 331 and 333. The first roll 331, also called the clean roll, is connected to an end of the first clean protective film 231 while the second roll 333, also called the clean roll, is connected to an end of the second clean protective film 233. This means that the first clean protective film 231 is connected with one end to the dirty protective film roll 230 and with the other end to the first clean roll 331 of the roll-carrier 210, while the second clean protective film 233 is connected with one end to the second dirty protective film roll 232 and with the other end to the second clean roll 333 of the roll-carrier 210. Because of this original configuration, the first dirty protective film roll 230 and the second dirty protective film roll 232 are attached to the rails 222 and 224 so that they can rotate but they cannot translate relative to the rails, while the first clean roll 331 and the second clean roll 333 of the roll-carrier 210 can both rotate and translate relative to the rails 222 and 224. As will be discussed later, the first and second clean rolls hold the clean parts of the films 231 and 233 while the first and second dirty rolls hold the dirty parts of the two films. To facilitate the rotation of the first and second dirty rolls 230 and 232, each may have its own motor 230A and 232A, respectively, as shown in Figure 2. All the motors and other movable parts may be coordinated by a global control system 240, which may include a processor 242, a memory 244, and a transceiver 246, configured to interact in a wireless manner with the various motors. [0032] The motor 310 of the roll-carrier 210 or an additional motor may also be used to rotate the first and second clean rolls 331 and 333 as necessary. To protect the rolls and the corresponding film that is rolled on the rolls from the ambient, as illustrated in Figure 4, a cover 340 may be attached to the frame 320. The cover may fully enclose the first and second clean rolls 331 and 333, with corresponding slots made in the cover to allow the protective films to be metered in and out of the cover. In one embodiment, a solar panel 342 may be located on the cover to charge the local power supply 312. In one application, a local controller 350, similar to the global controller 240, may also be provided on the cover (above or beneath) for communicating with the global controller 240 and exchanging data and commands, as discussed later. In one application, there may be hundreds or thousands of solar panel arrays that are serviced by plural protective systems 200 and each protective system 200 is capable to communicate, through its local controller 350, with the global controller 240, for coordinating when to replace a current dirty protective film with a clean protective film. The local and global controllers can also be used to assess the cleanliness status of the entire solar cell farm.

[0033] The deployment of a clean part of a protective film and the retrieval of a dirty part of another protective film are now discussed with regard to Figures 5A to 5C. Figure 5A shows the protection system 200 having a dirty part 233A of the second protective film 233 fully rolled over the active surface 102A of the plural solar panels 102, while the first protective film 231 is fully rolled on the first clean roll 331. Figure 5A also shows a detection sensor 500 that is located on a solar panel 102 and is configured to measure, for example, a light intensity behind the dirty part 233A of the second protective film 233. As the dirty part 233A of the second protective film 233, which initially was a clean part, is getting dirtier due to the dust, sand, and other particulates, the light intensity measured by the sensor 500 is decreasing for a same location of the solar panel and a same time of the day. This data is transmitted to the local controller 350, which shares the data with the global controller 240, which is programmed to instruct the local controller 350 to activate the roll-carrier 210 when the measured light intensity is below a certain threshold. In one embodiment, the local controller makes this decision without involving the global controller. When this happens, the local controller 350 activates the motor 310 of the roll-carrier 210, to move the roll-carrier from the first end 220A of the rail system 220 towards the second end 220B of the rail system 220.

[0034] In this regard, Figure 5B shows the roll-carrier 210 moving along the rail system 220, from left to right in the figure, while simultaneously performing the following acts: (1) metering a clean part 231 A of the first clean protective film 231 over the solar panel 102, from the first clean roll 331, and (2) removing or retrieving the dirty part 233A of the second clean protective film 233 from the solar panel 102, onto the second clean film roll 333. Arrows 510 and 512 indicate the rotational direction of the first and second clean rolls 331 and 333, with the first roll 331 metering out the clean part 231 A of the first clean film 231 and the second roll 333 metering in the dirty part 233A of the second clean film 233. Note that the motor 310 of the roll-carrier 210 ensures not only the rotation of the first and second rolls 331 and 333, but also the advancement of the entire roll-carrier toward the second end 220B of the rail system 220. In one embodiment, the motor 310 may include plural motors, one for moving the roll-carrier, one for rotating the first roll 331, and one for rotating the second roll 333. The motor 310 is controlled by the local controller 350 so that the translational speed v of the roll-carrier 210 is coordinated or matched by the rotational speed of the first and second rollers 331 and 333. In this way, the dirty part 233A of the second clean film 233 is removed from the solar panels 102 while at the same time, i.e., simultaneously, a new clean part 231A of the first clean film 231 is provided over the same solar panels 102.

[0035] In one embodiment, the clean film is made of plastic, is transparent, and has an adhesive substance spread over the face that is facing the solar panel. In one application, the first clean roll 331 has a biasing mechanism, for example, a spring, that pushes the first roll toward the active surface of the solar panel so that adherence between the clean film and the solar panel can happen. The same may be implemented for the second clean roll 333. The clean film may be a plastic wrap, that is made of polyvinyl chloride (PVC), which remains the most common component globally. PVC allows permeability to water vapor and oxygen transmission. A common, cheaper alternative to PVC is low-density polyethylene (LDPE). Other materials may be used as long as they are transparent to solar light and can be rolled on the rolls. A length of the first clean film 231 is a couple of times the length L of the entire solar panel array 100 that is encompassed by the rail system 220. For example, in one embodiment, the length of the first clean film 231 is about ten times the length L of the solar panel array, so that the same roller can be used multiple times before changing the entire roll. Note that the length L of the solar panel array 100 may be in the order of hundreds of meters. In one embodiment, the operation of replacing the dirty part of the second clean film 233 and placing the clean part of the first clean film 231 over the same solar panel array is repeated about once a week. Thus, if the dirty part of the clean film is replaced once a week with the clean part of the other clean film, the two clean films could last between 2 and 3 months before any need to change them.

[0036] Figure 5C shows the roll-carrier 210 arriving at the second end 220B of the rail system 220, so that the entire solar panel array 100 is covered by the clean part 231 A of the first clean film 231, while the dirty part 233A of the second clean film 233 has been almost entirely rolled over the second clean protective film roll 333. Hosting the dirty part 233A on the second clean film 233 on the second clean film roll 333 is temporary, as discussed later. The dirty part 233A would be unloaded from the second clean film roll 333 onto the second dirty protective film roll 232. Note that there is a gap G between the first clean roll 331 and the second clean roll 333, where no film is present. This gap G extends along the axis X, which is the displacement axis of the roll-carrier 210. The gap G may have a size in the mm or cm range.

[0037] At this point in the process, the first dirty protective film roll 230 has no clean film 231 on it, only the first clean roll 331 has such film. Also, the second dirty protective film roll 232 has no dirty part of the second clean film 233 on it, only the second dirty roll 333 holds the retrieved dirty part. Note that when the process is started in Figure 5A, both the first and second clean films 231 and 233 are entirely supported by the first and second clean film rolls 331 and 333, respectively, and the first and second dirty protective film rolls 230 and 232 hold no film. As the process advances, the dirty parts of the first and second protective films 231 and 233 are rolled onto the first and second dirty protective film rolls 230 and 232, and the clean parts of the first and second protective films 231 and 233 are supplied only by the first and second clean rolls 331 and 333. However, when the roll-carrier 210 is at the second end 220B of the rail system 220, the local controller 350 instructs the second clean film roll 333 to unroll the dirty part 233A and also instructs the second dirty protective film roll 232 to take the dirty part 233A. Thus, at this point, while the roll- carrier 210 is stationary, the roll 333 and the roll 232 rotate in unison to transfer the dirty part 233A to the roll 232. The local controller 350, knowing the length L of the solar panel 100, knows when the dirty part 233A has been fully transferred to the second dirty roll 232, and stops the transfer process. The second clean film roll 333 is now holding only the clean part of the second clean film 233.

[0038] When the global controller 240 or the local controller 350 detects that the clean part 231 A of the first clean film 231 is dirty (using the sensor 500), it instructs the roll-carrier 210 to move along axis X, back to the first end 220A. During this process, the clean part 231 A of the first clean film 231 , which now is a dirty part, is rolled onto the first clean film roll 331. In this regard, note that the dirty part of the first clean film 231 cannot be rolled directly onto the first dirty protective film 230 because of the adherence between the film 231 and the active surface 102A of the solar panel 102. For this reason, the first clean film roll 331 rotates over the dirty part of the first clean film 231 and simultaneously translates toward the end 220A, to peel off the now dirty part 231 A of the film 231 from the surface 102A of the solar panel 102. At the same time, the second clean roll 333 translates toward the first end 220A, while rotating, so that a new clean part of the second clean film 233 is provided over the solar panel 102.

[0039] When the roll-carrier 210 arrives at the first end 220A, the motor 230A of the first dirty protective film roll 230 is activated by the local controller 350 so that the now dirty part 231 A of the first clean film 231 , which is wrapped now around the first clean film roll 331, is transferred onto the first dirty protective film roll 230. In this way, the first clean film roll 331 unloads the dirty part of the first clean film 231, and is again ready to supply a clean portion of the first clean film 231 over the surface of the solar panel. Similarly, the second clean film roll 333, when arriving at the second end 220B, adjacent to the second dirty protective film roll 232, triggers the local controller 350 to activate the motor 232A of the second dirty protective film roll 232, so that the second roll 232 rotates and unloads from the second clean roll 333 the dirty part of the second clean film 233, which is wrapped around the roll 333.

[0040] In this way, a movement of the roll-carrier 210 between the two ends 220A and 220B of the rail system 220, collects the dirty part of one of the first and second clean films 231 and 233, and provides a clean portion of the other of the first and second clean films 231 and 233, with the first and second clean film rolls 331 and 333. Thus, as the process advances, the dirty parts of the first and second clean films 231 and 233 accumulate on the first and second dirty protective film rolls 230 and 232, respectively, while the first and second clean film rolls 331 and 333 meter out the clean portions of the first and second clean films 231 and 233. Note that the first and second clean film rolls 331 and 333 only temporarily hold the dirty portions of the first and second clean films 231 and 233, respectively, and as soon as the first and second clean film rolls 331 and 333 reach their corresponding ends 220A and 220B of the rail system 220, these rolls unload the dirty portions on their corresponding first and second dirty protective film rolls 230 and 232. This means that the action of removing the dirty portion of one of the first or second clean films from the solar panels is performed in a single journey of the roll-carrier 210, as the clean portion of one of the other one of the first and second clean films is provided over the solar panels.

[0041] A method for changing a dirty part of a film on the surface of a solar panel array and adding a clean part of another film is now discussed with regard to Figures 6 to 7C. In step 600, first and second clean protective films 231 and 233, rolled on corresponding first and second clean film rolls 331 and 333, are added to a roll-carrier 210. In step 602, an end of the first clean protective film 231 is attached to a first dirty protective film roll 230, and an end of the second clean protective film 233 is attached to a second dirty protective film roll 232. At this point, as shown in Figure 7A, the first clean protective film 231 is rolled onto the first clean film roll 331 , and a part 233A of the second clean protective film 233 fully covers an active surface of the solar panel array. In step 604, a local controller 240 and/or a global controller 350 receives a measurement from a sensor 500 located on the solar panel array and estimates whether the part 233A of the second clean protective film 233 is dirty. In step 606, when the local controller 240 determines that the part 233A of the second clean protective film 233 is dirty, the controller instructs the roll-carrier 210 to translate from one end 220A of a rail system 220 toward a second end 220B of the rail system 220. During this translation, the first clean film roll 331 meters out a clean part 231 A of the first clean protective film 231 to cover the solar panel array, while the second clean film roll 333 collects the dirty part 233A of the second clean protective film 233, from the solar panel array, as shown in Figure 7B. Note that the arrows in this figure indicate that both rolls 331 and 333 rotate and translate at the same time, while rolls 230 and 232 neither translate (they are fixedly attached to the rail system) nor rotate (their rotation motor was not yet activated).

[0042] In step 608, when the roll-carrier has arrived at the second end 220B of the rail system 220 (which can be detected with a contact or a sensor), the local controller 240 and/or the global controller 350 instructs the motor of the second clean film roll 333 to rotate in one angular direction, and the second dirty protective film roll 232 to rotate in the same angular direction, as illustrated by the arrows in Figure 7C, so that the dirty part 233A of the second clean protective film 233 is transferred from the second clean film roll 333 onto to the second dirty protective film roll 232. Note that the films 232 and 233 are in direct contact with the active surface of the solar panel 102. Also note that during this step, the first clean film roll 331 neither rotates nor translates, and the second clean film roll 333 only rotates, it does not translate. The local controller 240 and/or the global controller 350 allows this transfer to happen for a length L’ of the dirty part, which is substantially equal to a length L of the solar panel array 100, between the first and second ends of the rail system 220. Then, in step 610, the local controller 240 and/or the global controller 350 stops the rotation of the two rollers 333 and 232, and becomes idle. In step 612, the process returns to step 604, during which the local controller 240 analyzes a signal received from the sensor 500, which measures the dirt on the clean part of the protective film provided over the solar panel array. When the received signal has a value below a given threshold, the local controller 240 instructs in step 606 the roll-carrier 210 to move toward the other end of the rail system, to remove the dirty part of the first protective film 231 and to provide a clean part of the second protective film 233. This process then repeats until the first or the second protective films 231 and 233 are fully consumed and a new role needs to be placed on the roll-carrier. In one application, the operator of the system regularly inspects the roll-carrier to determine when one or both protective films have no clean parts left. However, in another embodiment, it is possible to have a sensor that determines when there is no clean part left.

[0043] An alternative method for protecting a solar panel from various particulates includes a step 800 of loading the first and second protective films 231 , 233 into the roll-carrier 210, and a step 802 of driving the roll-carrier 210 along a rail system 220, which extends along the solar panel, to simultaneously remove a dirty part of the second protective film 233 and to distribute a clean part of the first protective film 231 on a surface of the solar panel. In one application, the roll-carrier holds a first clean film roll 331 that is connected to the first protective film 231 , and a second clean film roll 333 that is connected to the second protective film 233.

[0044] The method may further include rolling the dirty part of the second protective film on the second clean film roll, translating the second clean film roll toward the second dirty protective film roll while rotating the second clean film roll, and rotating both the second dirty protective film roll and the second clean film roll to transfer the dirty part of the second protective film from the second clean film roll to the second dirty protective film roll. The first and second dirty protective film rolls are configured to rotate but not to translate. The method may further include a step of rotating the first dirty protective film roll with a first motor, a step of rotating the second dirty protective film roll with a second motor, a step of driving the roll-carrier with a third motor, a step of detecting with a sensor a light intensity through the first or second protective films, and a step of instructing the roll-carrier to move when a local controller determines that the light intensity is below a given threshold.

[0045] Those skilled in the art would understand that the local and/or global controllers can be programmed to replace the dirty party of one protective film with a clean part of the other protective film not only when the sensor 500 determines that the film is dirty, but also at a given time (for example, each week), or when the operator desires so. It is also possible to replace the dirty part with the clean part manually, i.e. , the operator can physically move the roll-carrier 210 from one end to the other end of the rail system 220 for this purpose. The two rolls 331 and 333 are configured to rotate independently from each other, either by the same motor 310, or with independent motors. Note that each of the rolls 331 and 333 can rotate and translate simultaneously or independently, i.e., only rotate or only translate as required by the various steps discussed above with regard to Figure 6. The film that is used for the protective films 231 and 233 may or may not have an adherent substance on the surface facing the active surface of the solar panel 102. However, due to its chemical composition, the film would tend to stick to the active surface of the solar panel 102, so that it is not possible to simple rotate rolls 230 and 232 in order to dispense or collect the film. In other words, rolls 331 and 333 need to collect the dirty part of the film, move next to the corresponding roll 230 and 232, and only then a pair of these rolls can rotate to transfer the dirty film from one roll to the other, as the adherence between the film and the active surface of the solar panel is at minimum now.

[0046] The disclosed embodiments provide a system for protecting from particulates a solar panel array, with a protective film. The system is also configured to automatically replace the part of the protective film that is dirty, with a clean portion. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

[0047] Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. [0048] This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.