Claims:I/We Claim:

1. An apparatus (100) for cleaning solar panels, comprising:
a pair of guide rails (102) extended over a length of solar panels (200) in parallel and external to the solar panels (200); and
a drive system (104), coupled to a brush (110) in contact with surface of the solar panels (200), wherein the drive system (104) comprises:
at least two belt drives (112) on the respective guide rail (102) and connected to the brush (110), to move the brush (110) in a forward direction to clean the solar panels (200), wherein the at least two belt drives (112) are coupled using a shaft (114) to drive the belt drives (112) synchronously along the guide rails (102).

2. The apparatus (100) as claimed in claim 1, further comprises a control system (118) to control movement of the drive system (104) along the guide rails (102).

3. The apparatus (100) as claimed in claim 1, further comprise a sensor actuating member (116) at each end of the guide rail (102) to signal a sensor (115) on the drive system (104) to change direction of the belt drives (112) when the drive system (104) reaches the end of the guide rail (102).

4. The apparatus (100) as claimed in claim 2, wherein the control system (118) controls the drive system (104) to initiate the drive at a pre-defined time period for a pre-defined cycles.

5. The apparatus (100) as claimed in claim 4, wherein the control system (118) initiates the drive system (104) at the pre-defined time period for the pre-defined cycles based on output voltages received from the solar panels (200), in operation sequence, wherein the output voltage is indicative of high sunlight intensity.

6. The apparatus (100) as claimed in claim 4, wherein the control system (118) draws power from an auxiliary solar panel (124) to drive the drive system (104), wherein control system (118) initiates the drive system (104) at the pre-defined time period for the pre-defined cycles based on output voltages received from the auxiliary solar panel (124), in operation sequence, and wherein the high output of voltage is indicative of high sunlight intensity.

7. The apparatus (100) as claimed in claim 1, wherein the drive system (104) is powered by a motor (120).

8. The apparatus (100) as claimed in claim 1, further comprises a support frame (122) to mount the guide rails (102) and the drive system (104).

9. The apparatus (100) as claimed in claim 1, wherein the brush (110) comprises a helically wound bristles.

10. A method for cleaning solar panels, the method comprising:
driving at least two belt drives (112), each positioned on respective guide rail (102) extended over a length of solar panels (200) and coupled to a brush (110) in contact with surface of the solar panels (200), wherein the at least two belt drives (112) are driven synchronously; and
controlling the drive at a pre-defined time period for a pre-defined cycles to clean the solar panels.

11. The method as claimed in claim 10, further comprising sensing the belt drives (112) reaching an end of the guide rail to signal to change direction of the drive.

12. The method as claimed in claim 10, wherein the belt drives (112) are driven at a pre-defined time period for a pre-defined cycles.

13. The method as claimed in claim 12, wherein the belt drives (112) are driven at the pre-defined time period for the pre-defined cycles based on output voltages received from the solar panels (200), in operation sequence, wherein the high output voltage is indicative of high sunlight intensity.

14. An apparatus (100) for cleaning solar panels, the apparatus (100) comprising:
a pair of guide rails (102) extended over a length of solar panels (200) in parallel and external to the solar panels (200);
a drive system (104), coupled to a brush (110) in contact with surface of the solar panels (200), wherein the drive system (104) comprises at least two belt drives (112) positioned on the respective guide rail (102) to move the brush (110) in a forward direction to clean the solar panels (200);
a sensor actuating member (116) at each end of the guide rail (102) to signal a sensor (115) on the drive system (104) to change direction of the belt drives (112) when the drive system (104) reaches the end of the guide rail (102); and
a control system (118) to initiate the drive system (104) at a pre-defined time period for a pre-defined cycles to clean the solar panels.

15. The apparatus (100) as claimed in claim 14, wherein the at least two belt drives (112) are coupled using a shaft (114) to drive the belt drives (112) synchronously along the guide rails (102).

16. The apparatus (100) as claimed in claim 14, wherein the control system (118) initiates the drive system (104) at the pre-defined time period for the pre-defined cycles based on output voltages received from the solar panels (200), in operation sequence, wherein the high output voltage is indicative of high sunlight intensity.

17. The apparatus (100) as claimed in claim 14, wherein the control system (118) draws power from an auxiliary solar panel (124) to drive the drive system (104), wherein control system (118) initiates the drive system (104) at the pre-defined time period for the pre-defined cycles based on output voltages received from the auxiliary solar panel (124), in operation sequence, and wherein the high output voltage is indicative of high sunlight intensity.

18. The apparatus (100) as claimed in claim 14, wherein the drive system (104) is powered by a motor (120).

19. The apparatus (100) as claimed in claim 14, further comprises a support frame (122) to mount the guide rails (102), the drive system (104) and the control system (118).

20. The apparatus (100) as claimed in claim 14, wherein the brush (110) comprises a helically wound bristles. , Description:FIELD OF INVENTION
[01] The present disclosure relates to a field of solar panels. More specifically, the present disclosure relates to an apparatus for cleaning solar panels.

BACKGROUND
[02] Generally, Photovoltaic (PV) Solar Panels are used extensively for generating electricity using sunlight. As known, the solar panels need to be installed in an open environment. As the solar panels are installed in the open environment, dust gets accumulated on surface of the solar panels. As a result, sunlight reaching the solar panels reduces and thereby reduces output and efficiency of the solar panels. Reduction in efficiency of the solar panels reduce power generating capacity and increases cost of the solar panel installations. In order to overcome problems related to the output and the efficiency, the solar panels need to be cleaned regularly.

[03] In order to clean the solar panels, typical cleaning systems use a robotic arm positioned on the solar panel or mounts a robotic arm on a mobile vehicle. The robotic arm used is expensive and consumes more power while in operation. Further, typical cleaning systems use a microcontroller to control the robotic arm or a mechanism to clean the surface of the solar panels. The microcontroller used for controlling the robotic arm includes complex controls to be configured and are expensive. Further, the robotic arm needs to be adjusted when the configuration of the solar panels is changed or relocated from one place to another.

[04] Alternatively, typical cleaning systems use sliding and/or brush systems to clean the surface of the solar panels. In order to operate the sliding and/or brush systems at pre-defined intervals, a microcontroller is used. As discussed above, the microcontroller includes complex controls to be configured and are expensive.

SUMMARY
[05] This summary is provided to introduce concepts related to apparatus for cleaning solar panels and the concepts are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[06] In one implementation, an apparatus for cleaning solar panels is disclosed. The apparatus comprises a pair of guide rails extended over a length of solar panels in parallel and external to the solar panels. The apparatus further comprises a drive system, coupled to a brush in contact with surface of the solar panels. The drive system comprises at least two belt drives on the respective guide rail and connected to the brush, to move the brush in a forward direction to clean the solar panels. The at least two belt drives are coupled using a shaft to drive the belt drives synchronously along the guide rails.

[07] In one aspect of the above implementation, the apparatus comprise sensors at each end of the guide rail to signal the drive system to change direction of the belt drives when the drive system reaches the end of the guide rail.

[08] In another aspect of the above implementation, the apparatus comprises a control system to initiate the drive system at a pre-defined time period for a pre-defined cycles to clean the solar panels.

[09] In yet another aspect of the above implementation, the control system initiates the drive system based on output voltages received from the solar panels, in operation sequence.

[10] In one alternate aspect of the above implementation, the control system draws power from an auxiliary solar panel to drive the drive system.

BRIEF DESCRIPTION OF DRAWINGS
[11] The detailed description is described with reference to the accompanying figures. In the figures, a reference number is used to identify a part of the apparatus for cleaning solar panels. The same numbers are used throughout the drawings to refer like/similar features and components.

[12] FIG. 1 illustrates an apparatus for cleaning solar panels, in accordance with an embodiment of the present disclosure;

[13] FIG. 2 illustrates the apparatus positioned external to solar panels to clean surface of the solar panels, in accordance with another embodiment of the present disclosure;

[14] FIG. 3 illustrates the apparatus comprising brush and belt drives, in accordance with another embodiment of the present disclosure;

[15] FIG. 4 illustrates the apparatus at mid-position when moving along the guide rails, in accordance with another embodiment of the present disclosure; and

[16] FIG. 5 illustrates the apparatus comprising an auxiliary solar panel, in accordance with yet another embodiment of the present disclosure.

DETAILTED DESCRIPTION
[17] The present disclosure relates to a method and an apparatus for cleaning solar panels. The apparatus comprises a pair of guide rails extended over a length of solar panels in parallel and external to the solar panels. The apparatus further comprises a drive system, coupled to a brush in contact with surface of the solar panels. The drive system comprises at least two belt drives on the respective guide rail and connected to the brush, to move the brush in a forward direction to clean the solar panels. The at least two belt drives are coupled using a shaft to drive the belt drives synchronously along the guide rails.

[18] The apparatus further comprises a control system to initiate the drive system at a pre-defined time period for a pre-defined cycles to clean the solar panels. The control system initiates the drive system based on output voltages received from the solar panels, in operation sequence. The apparatus further comprises sensors at each end of the guide rail to signal the drive system to change direction of the belt drives when the drive system reaches the end of the guide rail.

[19] The various implementations of the apparatus is explained with the help of Figures 1-5. Referring to FIGS. 1 and 2, an apparatus (100) for cleaning solar panels is shown. The apparatus (100) comprises a pair of guide rails (102) and a drive system (104). The apparatus (100) is coupled to solar panels (200) as shown in FIG. 2. Specifically, the apparatus (100) is coupled to the solar panels (200), by way of positioning the pair of guide rails (102) in parallel over a length of the solar panels (200) and the drive system (104) is placed on the pair guide rails (102). In other words, the pair of guide rails (102) is positioned external to the solar panels (200). In one example, the guide rails (102) are made up of aluminium or aluminium alloys. The drive system (104) comprises at least one sensor (115). Further, the guide rails (102) comprise a sensor actuating member (116) positioned at each end to determine termination of the guide rail (102).

[20] The drive system (104) is placed perpendicularly to the guide rails (102). The drive system (104) is further coupled to a brush (110). The brush (110) is extended over a length or a portion of the length of the drive system (104). The brush (110) is positioned to be in contact with surface of the solar panels (200). The drive system (104) comprises at least two belt drives (112) positioned on the respective guide rail (102). In one example, if the solar panels (200) are extended over a large area, then a supporting belt drive (113) may be provided, as shown in FIGS. 1 and 2. The supporting belt drive (113) is provided to support the drive system (104) when the width of the brush (110) or the drive system (104) is large. In one example, the belt drive (112) is a toothed pulley belt. The belt drives (112) placed on the respective guide rail (102) is coupled using a shaft (114) extended over the length of the drive system (104). In one example, the shaft (114) is positioned in parallel to the brush (110).

[21] The apparatus (100) further comprises a control system (118) positioned on the drive system (104). The control system (118) controls movement of the drive system (104) along the guide rails (102). The functioning of the control system (118) is explained in subsequent portions of the description. The apparatus (100) comprises a motor (120) to power the drive system (104). In one example, the motor (120) may be a DC motor.

[22] The operation of the apparatus (100) to clean the solar panels (200) is explained using a non-limiting example and FIGS. 1, 2 and 3. Although the operation is explained using the example, it should be understood that modifications may be made to the apparatus, in design or by supplementing additional parts to clean the solar panels. It should be noted that such modifications is within the scope of the current disclosure and is obvious to a person skilled in the art.

[23] Referring to FIG. 1 and 2, the guide rails (102) may be fixed to a support frame (122). The support frame (122) may be designed based on the alignment of the solar panels (200). For example, if the solar panels (200) are placed in parallel to surface of the ground, then the support frame (122) is positioned substantially parallel to the solar panels (200). Similarly, if the solar panels (200) are placed at an acute angle (e.g., 300) to the surface of the ground, then the support frame (122) is positioned at the angle (300) of the solar panels (200). As the apparatus (100) is positioned on the guide rails (102) which in turn is fixed to the support frame (122), weight of the apparatus (100) is not susceptible to the solar panels (200). Based on the above arrangement, the apparatus (100) may be configured to different size of the solar panels (200).

[24] In operation, the control system (118) controls movement of the drive system (104) along the guide rails (102). In one embodiment, the control system (118) controls drive of the drive system (104) at a pre-defined time period for a pre-defined cycles. The pre-defined time period indicates number of hours, days and so on. The pre-defined cycles indicate a forward and backward pass that the drive system (104) has to make along the guide rails (102). In other words, the pre-defined cycle indicates the movement of the drive system (104) from a home position (h) to an end (e1) of the guide rail (102) and movement of the drive system (104) from the end (e1) of the guide rail (102) to the home position (h).

[25] As presented above, the control system (118) drives the drive system (104) at the pre-defined time period for the pre-defined cycles (118). The control system (118) initiates the drive based on output voltages received from the solar panels (200). As known, the solar panels (200) generate power (in Volt) based on intensity of sunlight received. Depending upon intensity of the sunlight, the pre-defined time period (or day count) may be determined. Conventionally, the pre-defined time period is determined using a timer that calculates the time interval between days to initiate the drive. However, such arrangement for the timer requires continuous power supply. In order to avoid the control system (118) to draw continuous power from the power supply and to calculate the day count, the output voltages of the solar panels (200) are analysed.

[26] The control system (118) comprises a control circuit (not shown) to analyse the output voltages of the solar panels (200). Specifically, the control circuit analyses the output voltages to determine a mode of the control system (118). The mode may comprise a sleep mode, a stand-by mode and an operation mode. The sleep mode indicates the output voltage of the solar panels (200) being zero or very low. The sleep mode occurs when there is no sunlight. The stand-by mode indicates that the control system (118) to be awake but put on stand-by, when the output voltage of the solar panels (200) is positive but low. The operation mode indicates that the apparatus (100) is to be in operation sequence and the day count needs to advance, when the output voltages of the solar panels is high and normal, indicating direct sunlight. After the operation sequence is trigged in the operation mode, if the output voltage reduces then the control circuit changes the day count, indicating that a day has passed. In other words, when the output voltage reaches the operation mode or level, the day count is advanced. At the time of operation mode, the control system (118) initiates the cleaning cycle when the day count reaches a pre-set limit, e.g., two days. In another scenario, if the output voltage reduces slightly and increases again, such as during a passing cloud, then the output voltage will go below the operational level and again rise to the operational level. The above scenario triggers a false day-count. Triggering of the false day-count is prevented by making sure that once operational level of the output voltage is reached, the control system (118) ignores minor shift in output voltages and would get triggered only when the output voltage reaches 'stand-by' level.

[27] If the operation mode is reached upon detection of the operation sequence, then the control circuit counts a day count or the pre-defined time period. After reaching the desired day count, the control system (118) drives the drive system (104) for the pre-defined cycles. For example, consider the control system (118) is configured to drive the drive system (104) after every two days for three cycles. The control circuit counts the number of days based on the output voltages received from the solar panels (200), in operation sequence i.e., operation mode. After counting the high output voltages for two times (two days are passed), in operation sequence, the control system (118) sends a signal to the drive system (104). Upon receiving the signal, the drive system (104) draws power from the motor (120) to move in a forward direction. Specifically, the drive system (104) starts from the home position (h) to the end (e1) of the guide rails (102) and returns to the home position (h). After completing the pre-defined cycles, the control system (118) resets the day-count to zero and repeats the operation as explained above.

[28] The movement of the drive system (104) along the guide rails (102) is explained in greater detail below. After the control system (118) signals the drive system (102) to initiate the drive, the drive system (102) draws power from the motor (120). Specifically, the motor (120) powers one belt drive (112) on the guide rail (102). By powering one belt drive (112) on a first guide rail (102), use of two or more motors to power the each belt drive is avoided. When the belt drive (112) on the first guide rail (102) is powered, the belt drive (112) on the second guide rail (120), connected via the shaft (114), is also moved in the forward direction. By connecting the shaft between the belt drives (112), the two belt drives (112) are driven synchronously at a constant speed. As both the belt drives (112) move at constant speed, slippage of the belt drives (112) due to inconsistent speed is avoided.

[29] In one implementation, the belt drive (112) used for driving the drive system (104) is a toothed pulley. Further, the belt drive (112) may comprises a spring operated rollers to provide positive, constant and adjustable traction force. By using the spring operated rollers, slippage of the belt drive (112) is prevented when the apparatus (100) is positioned at an acute angle from the surface of the ground. The positive traction force achieved by the spring operated rollers ensure that there is no sliding friction and wastage of energy.

[30] The toothed belts used may be non-metallic and may have a rubberised/soft backing to avoid damage or scratch the solar panels. Although use of the spring operated rollers is explained, it is apparent to the person skilled in the art to use a hydraulic or a pneumatic system.

[31] As discussed above, the drive system (104) is coupled to the brush (110) that is contact with the surface of the solar panels (200). As the drive system (104) moves along the guide rails (102), the brush (110) cleans the surface of the solar panels (200). In one embodiment, the brush (110) may comprise a helically wound bristles. The helically wound bristles are non-metallic bristles and does not scratch the surface of the solar panels (200) when they are in contact. As the drive system (104) moves from the home position (h), the brush (110) rotates at a certain speed to sweep dust on the solar panels (200). Due to helical structure of the brush (110), the dust is moved towards side of the solar panels (200) and is thrown away from the edges of the solar panels (200). As the brush (110) rotates constantly when the drive system (104) is powered, the helically wound bristles create an airflow to remove the dust from the surface of the solar panels (200) and throws the dust in forward or sideways.

[32] In one implementation, the brush (110) may be provided with a wiper (128) at each end of the brush (110) to remove dust from the helically wound bristles, as shown in FIG. 3. The wiper (128) does not allow the dust to be thrown back on the surface that is already cleaned at the time of the brush (110) cleaning the surface of the solar panels (120).

[33] As discussed above, the drive system (104) may comprise the sensor (115). Further, the guide rails (102) comprise the sensor actuating member (116)at each end of the guide rail (102). Referring to FIG. 4, the drive system (104) at the mid-position when travelling from the home position (h) to one end (e1) of the guide rail (102) is shown. As the drive system (104) moves towards the end of the guide rail (102), the sensor (115) receives a signal from the sensor actuating member (116) indicating that the drive system (104) is approaching the end of the guide rail (102). After receiving the signal, the sensor (115) in turn signals the drive system (104) to change the direction of the belt drives (112). In operation, when the control system (118) initiates the drive, the drive system (104) moves from the home positon (h) to end (e1) of the guide rail (102) and returns to the home position (h) to complete a cycle. After completing the cycle, the control system (118) limits movement of the drive system (104). The above operation is performed for the pre-defined cycles as may be configured by a user. In one example, if the solar panels are in an environment having relatively clean (or little dusty) conditions, the time period may be set as four or more days and one cycle to clean the surface of the solar panels. Similarly, if the solar panels are in dusty conditions, the time period may be as one day and two or more cycles to clean the surface of the solar panels. Although the present disclosure disclose the sensor actuating member (116) to be positioned at the end of the guide rails (102), it must be understood that the sensor actuating member (116) may be positioned at different points along the guide rails (102) to change the direction of the brush (110) and the belt drives (112). The direction of rotation of the brush (110) is reversed, such that the dust is not thrown back on the solar panels (200).

[34] After completing the pre-defined cycles at the pre-defined time period, the control system (118) resets the day count to zero and recalculates the day count until operation sequence is obtained to initiate another drive to clean the surface of the solar panels (200). The control system (118) uses an adjustable delay or feedback loop and re-generating braking to stop and reverse the drive system (104) at the end of pre-defined cycles to ensure that the drive system (104) stops completely before the drive system (104) initiates another cycle. Further, the control system (118) ensures that mechanical or electrical system is not overloaded or damaged by the momentum of the drive system (104) in reverse direction. Based on the above, the control system (118) eliminates need for electromagnetic or other type of braking at the end of drive, thereby reducing cost and consumption.

[35] It is understood that the power required to drive the drive system (104) is only when the control system (118) determines the operation mode based on the output voltages as discussed above. The time to operate the apparatus (100) to complete the pre-defined cycle at the pre-defined time period is relatively small when compared with the time that the apparatus (100) is idle or at sleep mode. In other words, the apparatus (100) is inactive during at nights, evenings, and so on. During the inactive period, the control circuit switches off other circuits and consumes very negligible power.

[36] In one embodiment, the control system (118) may have a plurality of hardware switches to set the pre-defined time period and the pre-defined cycles to initiate the drive system (104). A hardware switch of the plurality of hardware switches may be used to set output voltages of the solar panels (200) powering the drive system (104). By providing the hardware switches, use of a microprocessor or a logic circuit and associated maintenance is avoided.

[37] The above description is explained considering the control system (118) receives the output voltages from the solar panels (200) to drive the drive system (104). In another embodiment, the apparatus (100) may comprise an auxiliary solar panel (124) positioned on the drive system (104), as shown in FIG. 5. The control system (118) may receive the output voltage from the auxiliary solar panel (124) to initiate the drive system (104). As discussed above, the control system (118) initiates the drive system (104) when the operation mode is reached, i.e., high output voltage in operation sequence. When the control system (118) does not reach the operation mode or when the drive system (104) completes the pre-defined cycles at the pre-defined time period, the output voltage of the auxiliary solar panel (124) is connected to a battery (126). The output voltage of the auxiliary solar panel (124) is used to charge the battery (126) until the operation mode is reached. The battery (126) may power the control system (118) to control the drive system (104).

[38] In one embodiment, the control system (112) may be covered using a box structure (130). The control system (118) is covered to protect it from rain or external damage. In one embodiment, the box structure (130) may be placed in parallel to the auxiliary solar panel (124) as shown in FIG. 5.

[39] Although implementations of apparatus for cleaning solar panels have been described in language specific to structural features, it is to be understood that the appended claims are not necessarily limited to the specific features described. Rather, the specific features are disclosed as examples of implementations for cleaning solar panels.

[40] Advantages:

[41] The guide rails are fixed on a support frame. Therefore, there is no need for additional alignment of the solar panels or in other words any mis-alignment in solar panels are taken care of.

[42] As the apparatus are positioned on the guide rails which in turn is placed on the support frame, the weight of the apparatus is not susceptible to the solar panels.

[43] The apparatus uses two toothed belt drive that runs in synchronous with special friction lining to provide positive and even traction.

[44] The brush has helically wound soft bristles to clean the surface of the solar panels along with edges without scratching. Because of the brush design, small obstruction at the edges of the solar panels are also cleaned. Since the bristles are soft and flexible, small misalignments in adjacent solar panels can be taken care of.

[45] The brush due to its unique helical design and ability to throw the dust away aided by airflow due to high speed of rotation, does not scratch surface of the solar panel.

[46] The control system does not use a microprocessor and software to adjust the number of cleaning cycles and the time period to clean the solar panels. Thus avoiding constant power consumption and therefore cost incurred due to a microprocessor based circuit. Once configured, the control system cleans the solar panels at the pre-defined time period for pre-defined cycles.

[47] The control system can be set at pre-determined days and cycles to suit various dusty conditions.