DESC:FIELD OF INVENTION:

The invention relates to an Automated PV Module Dry Cleaning System (AMCS).

OBJECT OF INVENTION:

Feasibility of deploying large number of labour and consuming millions of litres of potable water from a locality become key concerns to clean 100s of MW to GW-scale solar photovoltaic (PV) power plants. The system as per invention is an automated solar PV module dry cleaning system bundled with its soiling measurement station, helps PV power plant operators to:
• minimize wet cleaning cycles, water consumption and labour requirement, reducing cost of cleaning
• monitor real time soiling levels and exercise better control on cleaning frequency and efficiency
• improve energy generation by increasing cleaning frequency
• eliminate risk of uncertainty in availability and cost of manpower & water from affecting energy generation

DESCRIPTION OF INVENTION:

Dust and dirt tend to settle on the surface of solar PV modules over time and thereby impact the electricity generating capacity of the module. Hence routine cleaning of the solar PV module is very essential. Regular cleaning prevents buildup of dust and residue and ensures that solar PV modules are operating optimally at all times.

The objective of the invention, helps to achieve an efficient solar photovoltaic power plant by maintaining the cleanliness of the PV module surfaces. With clean surfaces of the solar PV modules, energy losses due to dust or debris are minimized. The currently available systems are costly and labour oriented. Also such known systems demand potable grade water for cleaning, all of which are not conducive as solar PV modules are installed in remote areas.

The present invention is a robotic module cleaning system designed to dry clean the solar PV modules as it passes over the array. A rotary brush running along the entire length of the array wipes away the dust deposited on the PV modules and prevents buildup of soiling level.

DRAWINGS AND ILLUSTRATIONS
The description is provided only with illustration of figures 1-18.

Figure 1 & 1A illustrate Isometric View of a version with suspension wheels and handles (2m variant is shown for depiction) and a version without suspension wheels and handles (a 4m variant is shown for depiction)
Figure 2 & 2A illustrate Top View of a version with suspension wheels and handles (2m variant is shown for depiction) and a version without suspension wheels and handles (a 4m variant is shown for depiction)
Figure 3 & 3A illustrate Side View of a version with suspension wheels and handles (2m variant is shown for depiction) and a version without suspension wheels and handles (a 4m variant is shown for depiction)
Figure 4 & 4A illustrate Front View of a version with suspension wheels and handles and a version without suspension wheels and handles
Figure 5 & 5A illustrate Bottom View of a version with suspension wheels and handles (2m variant is shown for depiction) and a version without suspension wheels and handles, with middle bogie assembly (a 4m variant is shown for depiction)
Figure 6 & 6A illustrate 3D Model with transparent covers to show internal assembly of versions with suspension wheels, handles (2m variant is depicted), middle bogie (4m variant is depicted) respectively
Figure 7 & 7A illustrate 3D model without bogie plate covers of versions with suspension wheels, handles (2m variant is depicted), and without (4m variant is depicted) showing the motor mounting arrangement, pulley and belt arrangement and wheels
Figure 8 & 8A illustrates Main Components of the Mobile Cleaning Robot
Figure 9 & 9A illustrates main electrical components
Figure 10 & 10A illustrate Components in Main/ End Bogie Plate Assembly
Figure 10B & 10C illustrate Middle Bogie Plate Components
Figure 11 illustrates Cover Design
Figure 12 illustrates Suspension Wheels on Top and Edge Faces
Figure 13 & 13.A illustrates 3D model handle and topple safety rollers
Figure 14. Docking Station
Figure 15. Reversing Station

Components of AMCS Component Number in patent Overall Assembly Assembly number in patent Assembly Part Part number in patent Part Variants Part number in patent
Robot Body A Base Structural Framework A.1. Bogie Plate A.1.1. Bogie Plate (End Plate) A.1.1.1
Bogie Plate- Middle A.1.1.2
Structure support frame A.1.2. Robot Length Adjustment Provision on Support Frames And Bogie Plates A.1.2.1
Structure support channel A.1.3.
Structure support rod A.1.4.
Center Stud A.1.5.
Handles A.1.6.
Cleaning Elements A.2. Cylindrical Roller Brush Assembly with helically wound bristles and shafts A.2.1. Cylindrical Roller Brush with helically wound bristles or referred here as helical brush A.2.1.1.
Helical brush shaft A.2.1.2.
Strip Brush A.2.2.
Plummer Block for helical brush shaft A.2.3.
Bearing A.2.4.
Brush Spacer A.2.5.
Wheel System A.3. Drive Wheel. A.3.1.
Edge wheel with bearing A.3.2.
Middle support wheels A.3.3.
Suspension wheel assembly A.3.4. Suspension wheels A.3.4.1.
Lever arm assembly A.3.4.2.
Suspension springs A.3.4.3.
Fixing clamps A.3.4.4.
Wheel clamp A.3.5. Edge wheel clamp A.3.5.1.
Drive wheel shaft A.3.6. Drive Wheel Shaft A.3.6.1.
Center Drive Shaft. A.3.6.2.
Edge Wheel Pin A.3.7.
Edge Suspension Spring A.3.8.
Propeller Rod A.3.9.
Shim for Suspension in edge wheel A.3.10.
Topple safety rollers A.3.11. Polymer rollers A.3.11.1.
Clamps for topple safety rollers A.3.11.2.
Drive System A.4. Motors A.4.1. Drive motor A.4.1.1.
Brush motor A.4.1.2.
Motor Clamp A.4.2. Drive Motor Clamps (On Motor) A.4.2.1.
Drive Motor Clamps (On Bogie) A.4.2.2.
Brush Motor Clamp (On Bogie) A.4.2.3.
Brush Motor Clamp (On Motor) A.4.2.4.
Pulley system A.4.3. Pulley Centre Pin A.4.3.1.
Drive Pulley A.4.3.2.
Timing Belt A.4.3.3.
Bearings A.4.3.4.
Pulley Plummer block A.4.3.5.
Frame adjustment slot A.4.4.
On-Board Controller System A.5. Embedded Controller A.5.1.
Controller Back Plate A.5.2.
On-board sensors A.5.3. Edge sensor A.5.3.1.
Encoder for motor A.5.3.2.
Edge sensor Clamp A.5.3.3.
Control switches A.5.4.
Power Supply System A.6. Battery bank enclosure A.6.1.
Battery Clamp or Bottom Clamp A.6.2.
Battery Back Plate A.6.3.
Charge controller A.6.4.
Solar PV Module A.6.5.
Top Cover A.7.1.
Bogie Cover A.7.2.
Logo A.7.3.
Name Plate A.7.4.
Square flange for wiring A.7.5.
Docking Station and Reversing Station B Extension rail B.1. Extension rail on docking station B.1.1.
Extension rail on reversing station B.1.2.
Guiding channel B.2. Sensor guide channel B.2.1. Sensor guide channel - docking station B.2.1.1.
Sensor guide channel - reversing station B.2.1.2.
Wheel guide channel B.2.2. Wheel guide channel - docking station B.2.2.1.
Wheel guide channel - reversing station B.2.2.2.
Self-cleaning cross strip brush B.3. Self-cleaning cross strip brush for charging solar PV module B.3.1.
cross strip brush for self-cleaning helical brush B.3.2.
Edge baffles B.4.
Purlins for module and robot support B.5.
Optional Foundation B.6.
Optional Structure Post B.7.
Power Supply System with Provision for Dual Option Battery Charging Unit C MPPT charge controller C.1.
Solar PV module C.2.
SMPS based charging unit C.3.
Indication lamps C.4.
Battery bank C.5.
Wireless real-time monitoring and control system D Centralized controller D.1. Hand-held controller D.1.1.
SCADA-based controller D.1.2.
Cloud-based controller D.1.3.
Communication module D.2. On-board communication module D.2.1.
Communication gateway D.2.2.
Soiling Measurement Station E Solar PV modules E.1. Soiled solar PV module E.1.1.
Clean solar PV module E.1.2.
Charging solar PV module E.1.3.
Embedded controller E.2.
Battery bank E.4.
Mounting Arrangement E.3.

OVERALL COMPOSITION AND PARTS
The invention relates to an Automated Solar PV Module Dry Cleaning System which encompasses the following six distinct components:
A. PV module cleaning robot(s) comprised of
a. a base structural framework [A.1.] made of support frames [A.1.2.], support channels [A.1.3.], support rods [A.1.4.], end bogie-plates [A1.1.1], middle bogie-plates [A.1.1.2], center studs [A.1.5.] and handles [A.6.]
b. cleaning elements [A.2.] connected to the base structural framework and comprised of a cylindrical roller brush assembly with helical winding of polymer bristles, also referred as helical brush assembly [A.2.1.], strip brushes [A.2.2.], plummer blocks [A.2.3.], bearings [A.2.4], and brush spacer [A.2.5.]
c. wheel system [A.3.] connected to the base structural framework and consisting of drive wheels [A.3.1.], edge wheels [A.3.2], middle support wheels [A.3.3.], suspension wheel assembly [A.3.4.], wheel clamps [A.3.5.], drive wheel shafts [A.3.6.], edge wheel pin [A.3.7.], edge wheel suspension springs [A.3.8.] housed on the bogie-plates, propeller rod [A.3.9.] interconnecting drive wheels on opposite bogie-plates, springs and shim [A.3.10] on edge wheel for suspension, and topple safety polymer rollers [A.3.11].
d. drive system [A.4] consisting of motors [A.4.1.] for powering wheels and brushes, motor clamps [A.4.2.], timing belt and pulley system [A.4.3.] housed on bogie-plates and connected to the base structural framework,
e. on-board control system [A.5.], comprised of robot on-board embedded controller [A.5.1.], associated sensors [A.5.3.] and mounting arrangement [A.5.2.]
f. power supply system [A.6.] including robot battery bank [A.6.1.] and ancillaries like power cables, optional PV modules [A.6.6.], mounting arrangement [A.6.2.], [A.6.3.] and [A.6.4.], MPPT charge controller and enclosures [A.6.5.]
g. Covers [A.7.] including top and motor covers are fixed and supported on the base structural framework [A.1.].

The robots operate on the solar PV arrays during cleaning period and rest on the docking stations attached to the PV arrays after cleaning routine as described below.
B. One set of dedicated docking and reversing station per robot which extends out of solar PV module array to ensure that brush moves out of the solar PV module area completely and is comprised of extension rails [B.1.] for robot to move and rest on, guiding channels [B.2.] for sensors, self-cleaning cross strip brush [B.3.], edge baffles [B.4.] to restraint forward motion of robot, optional solar PV module for charging the robot’s battery.
C. One power supply system provision for dual option battery charge controller unit [C] per robot [A] with MPPT based charge controller [C.1.] via solar PV module [C.2.] which is housed either in the docking station [B] or on the robot body [A] itself or SMPS [C.3] based charging via grid supply, indication lamps [C.4.] and the battery bank [C.5.].
D. Wireless real-time monitoring and control system [D] for keeping track and controlling the robot through on-board embedded controller [A.5.1.], on-board sensors [A.5.3.] and control switches [A.5.4.] for emergency manual overriding. The system can be monitored and controlled remotely by communicating wirelessly to the onboard embedded controller via a handheld remote controller/ cloud/ SCADA based centralized controller [D.1.] which is also part of the system.
E. A soiling measurement station (E) that measures soiling loss levels in terms of the short circuit current mismatch between soiled solar PV module(s) [E.1.1] and clean solar PV module(s) [E.1.2.] through an embedded controller [E.2.] installed in the solar PV power plant and integrated wirelessly via centralized controller [D.1.] on cloud or site SCADA is also provided.

CONSTRUCTION & DESIGN DETAILS:
Robot:
The base [A.1] of the robot [A] body is a rectangular framework comprising of two hollow rectangular support frame pipes [A.1.2], optional middle bogie plate(s) [A.1.1.2] and two end bogie plates [A.1.1.1] connected with each other at right angles. Bogie–plates [A.1.1] are near-trapezoidal shell like support plates which have integral parts for housing several other components of the robot body such as the motors [A.4.] powering helical brush [A.2.1], drive wheels [A.3.1] edge wheels [A.3.2.], middle drive wheels [A.3.3.], suspension assembly [A.3.4.], connection of topple safety rollers [A.3.11.], handles [A.1.6.] and their associated accessory and fixing parts.

The end bogie plates [A.1.1.1.] are placed facing each other such that the side with provisions for fixing motors [A.4.] is turned outwards and side with drive wheel [A.3.1.] fixing provisions is facing inwards, and at a spacing equal to the length of the robot and are joined/connected by means of two rectangular support frame pipes [A.1.2] inserted through the slots on the bogie plates [A.1.1] at right angles to the bogie-plate face [A.1.1] and bolted together. The rectangular support pipes [A.1.2.] are connected to the frame connection slots provided on the bogie plates [A.1.1]. One rectangular pipe [A.1.2] is connected to the left slot on the top end bogie plate [A.1.1.1] and to the right slot on the bottom end bogie plate [A.1.1.2]. The other rectangular support frame pipe is connected to the right slot on the top end bogie plate [A.1.1.1] and to the left slot on the bottom end bogie plate [A.1.1.2]. Additional support channels [A.1.3] are used to interconnect the two rectangular support-frame pipes [A.1.2]. Support channels [A.1.3] are positioned parallel to the bogie-plates [A.1.1], each end of a support channel [A.1.3] fixed on the top face of one rectangular support-frame pipe [A.1.2] each. Two (minimum one) pairs of support channels [A.1.3] are connected to each modular section of robot body, at one-third and two-third length of the support-frame pipes [A.1.2] between two bogie plates [A.1.1]. The support channels [A.1.3] help to maintain rigidity and to distribute loads more uniformly to prevent sagging of support-frames [A.1.2] and also act as the platforms on which the on-board embedded controller [A.5.1] and the battery enclosure [A.6.1.] are mounted. Additional reinforcement for the robot body [A.1] is provided using support pipes [A.1.6] which are connected between the two bogie plates [A.1.1] of each section, one on each side, below the slots provided for the connection of support frame pipes [A.1.2]. Refer fig. 8. The support pipes can be optionally either replaced or reinforced with a turnbuckle or cross connector rods [A.1.6.2.] between the end bogie plates [A.1.1.1.] and support channels [A.1.3.] to provide additional strength and bracing by redistributing the forces on bogie plates and prevents its twisting or expansion of the bogie plate even under highest load on top bogie plate at 45 degree tilt of PV module array (Fig.8). The through shaft/ support pipe [A.1.6.] can be provided perforations and connected to a water source to enable the system to do water cleaning as well.

The design of the robot body [A.1] is modular and can be extended to any length (up to 10m) by interconnecting 2 meter segments (comprised of 2m rectangular support frame pipe sections [A.1.2], two end bogie-plates [A.1.1.1] and two or more middle bogie plats [A.1.1.2]) of the framework as explained above. Modular 2m (or 1m) long units are repeated and connected with intermediate middle bogie assembly [A.1.1.2] to create robots of higher lengths. Refer fig.8.
For 4m long robot frames, a middle bogie plate [A.1.1.2] replaces the bottom end bogie plate [A.1.1.1] in the first modular section instead of bottom end modular structure and a middle bogie plate [A.1.1.2] replaces the top end bogie plate [A.1.1.1] in the last section. In all the intermittent sections for any robot length higher than 4m, the rectangular support frame pipes [A.1.2] will be connected to middle bogie plates [A.1.1.1] at both ends instead of end bogie plates [A.1.1.2]. Multiple sections are joined together at the respective middle bogie-plates [A.1.1.2] by means of centre studs [A.1.1.3] to form higher length robots. Refer fig. 8.

Brushes [A.2.] for cleaning the solar PV module are mounted on the above base structure [A.1.] of the robot [A]. Each 2m section of the robot structure frame has one (or more) cylindrical brush [A.2.1] with helically wound soft polymer bristles mounted at the centre of the robot frame, its axes running parallel to the support frame and the length of the robot [A] and two strip brushes [A.2.2] mounted along the edges along the length of the robot [A]. The two ends of the helical brush [A.2.1] are connected to the centre of the bogie-plates [A.1.1] of respective section via brush shafts [A.2.1.2.] and bearings [A.2.4]. The strip brushes [A.2.2] are connected to the support frame pipes [A.1.2], one on each side, bolted to the pipe along its length.

The helical brush sections [A.2.1.] of individual 1m or 2m frame sections are also joined together by interconnecting the brush shafts for transmission of torque to the successive helical brush sections [A.2.1]. Refer fig. 8.

The wheels [A.3.] of the system are attached to the bogie plates [A.1.1]. The drive wheels [A.3.1.] and middle drive wheels [A.3.3.] are symmetrically placed on the bogie plates [A.1.1.1 and A.1.1.2.] equidistantly, on either side of the point where helical brush shaft [A.2.1.2.] is connected to the bogie plate [A.1.1.] through the wheel shaft [A.3.6.] and axis of rotation are parallel to those of the helical brush [A.2.1.]. The edge wheels [A.3.2.] are connected to the bogie plate perpendicular to the drive wheels [A.3.1.] below the drive wheels [A.3.1.]. For lengths higher than 2m, additional middle support wheels [A.3.2.] are provided in the middle bogie plate [A.1.1.2] to further reduce point loads and align the movement of the robot frame [A]. (fig. 10 and 10.A). The drive wheels move on the top edge and the edge wheels move on the side edge of the Aluminum frame of solar PV module and do not touch the glass of PV modules The number of wheels placed on the top and side edges of the Aluminum frame per robot system is designed to divide the total load and minimize load transfer on the PV module frame. Minimum number of drive wheels [A.3.1.] and minimum number of edge wheels [A.3.2.] is four in the 2m robot structure. In longer robots, there will be minimum (2n- 2) middle drive wheels [A.3.3.] where n is the number of conjoined 2m sections. The middle support wheels [A.3.3.] are coupled to one pair of drive wheels [A.3.1.] through propeller rod [A.3.9.] for uniform transfer of torque. The load transfer on the PV module Aluminum frame is lower than its threshold load capacity estimated based on the section modulus and yield strength and hence no load is transferred to the underlying glass and solar cells. This design prevents the transfer of load to the glass and transfer of any stress to solar glass or underlying solar PV cells.

The suspension assembly [A.3.4.] of the system is also connected to the outer edges of bogie plates [A.1.1.]. It is comprised of suspension wheels [A.3.4.1], lever arms [A.3.4.2.], suspension springs [A.3.4.3.] and suspension assembly fixing clamps [A.3.4.4.]. All four corners of the robot are provided with the suspension assembly [A.3.4.], which is connected to the end bogie plates. Each suspension assembly [A.3.4.] is comprised of suspension wheels [A.3.4.1] that run both on top surface of the PV module frame (Aluminum frame surface parallel to glass surface) and on the PV module frame edge (Aluminum frame surface perpendicular to glass surface). The suspension wheels [A.3.4.1] are sized to have the right diameter to cross module to module gap without getting stuck or without requiring any additional external force. Suspension springs [A.3.4.3.] are connected between the suspension lever arm [A.3.4.2.] and suspension assembly fixing clamps [A.3.4.4.]. Spring activated suspension assembly [A.3.4.] is designed to constantly maintain contact between the suspension wheels and PV module, to absorb sudden impacts due to a fall in the surface level between two adjacent modules and to flex itself while the robot climbs the rise in surface level between two adjacent modules. This arrangement minimizes the impact on Aluminum frame and glass of solar PV modules (Fig. 12).

The edge wheels [A.3.3.] connected at the bottom end bogie plate [A.1.1.1] of the robot [A] is provided with spring suspension [A.3.8.] which is connected to the edge wheel clamp [A.3.5.1] on one end and the other ends of the suspension springs are terminated on the bottom end bogie plate [A.1.1.1.] through a shim [A.3.10]. This arrangement always maintain contact with the bottom edge of the array and prevents skew due to lag or lead at bottom edge of robot by enabling easy adjustment of robot at locations of PV module misalignments (Fig. 10)

The cluster of wheel [A.3.] and cleaning system [A.2.] is powered by a drive mechanism [A.4] which consists of separate DC motors at the top end bogie plate and bottom end bogie plate [A.1.1.1] connected to the drive wheels [A.3.1.] and helical brushes [A.2.1.]. The drive motor [A.4.1.] and pulley system [A.4.3.], housed in the end bogie plates [A.1.1.1.], form the drive system for the drive wheels [A.3.1.]. The drive motors [A.4.1.] are fixed on the end bogies plate [A.1.1.1.] through drive motor clamps [A.4.2.1.] and [A.4.2.2.]. The shaft of drive motor [A.4.1.1.] is connected to one of the drive pulleys [A.4.3.3.] from the customized pulley system which is interconnected via a timing belt [A.4.3.4.] for delivering torque equally to each of the drive wheels [A.3.1.] on each end bogie plate [A.1.1.1.]. The shafts of drive motors [A.4.1.1.] are connected to the drive pulleys [A.4.3.3.] connected to bogie plates [A.1.1.] at the respective position. The pulley plummer blocks and housings [A.4.3.7.] are with fitted bearings [A.4.3.5.]. The pulleys [A.4.3.3.] are mounted on bogie plates [A.1.1.] via pulley plummer blocks and housing [A.4.3.7.]. Encoders [A.5.3.2.] at each drive motor give feedback to the controller [A.5.1.] to adjust speed of each motor independently and prevent skew between top and bottom bogie plates [A.1.1.] of the robot [A] (Fig. 10 and 10.A.).

The drive wheels [A.3.1.] at each section (top edge or bottom edge) are connected to the corresponding motor [A.4.1.] through the above customized arrangement comprising of pulleys [A.4.3.3.] and belt [A.3.4.] which uniformly delivers torque to each drive wheel [A.3.1.]. Thus all drive wheels [A.3.1.] are uniformly powered, making the motion of the robot [A] smooth.

The wheel design, wheel diameters and width, motor rating and suspension assembly are designed such that the robot can work in rugged terrain and PV array installations and cross over module to module gaps, to climb over steps, module misalignments or slopes and array tilts acceptable as per industry requirement without any additional support or structure

Separate brush motor(s) [A.4.1.2.] to ensure independent speed control for helical brush [A.2.1.] from drive wheels [A.3.1.]. If an area has to be cleaned more intensely than the other, brush can be rotated at full speed while holding the drive wheels still. The brush motors [A.4.2.] are fixed on the end bogies plate [A.1.1.1.] through brush motor clamps [A.4.2.3.] and [A.4.2.4.]. The shaft of brush motor [A.4.1.2.] is connected to the brush shaft [A.2.1.2.].

Central rotary helical brush(es) [A.2.1.1.] run along the full length of the robot [A]. The helical brushes rotate in opposite direction to the drive wheels [A.3.1.], pushing dust forward with respect to the direction of the robot’s motion and out of the array.

In addition to rotary helical brush [A.2.1.1.], the system has static strip brushes [A.2.2.] with longer bristles for higher contact length/ overlap with PV module surface on both sides, to eliminate unclean areas at the helical brush [A.2.1.] segment joints. The strip brush [A.2.2.] sweeps away the dust in the direction of robot’s linear movement. The static strip brushes [A.2.2.] along the entire length of the robot on both sides, ensures cleaning even when the helical brushes [A.2.1.1.] lose contact with PV module glass at module surface misalignments which causes a step for the robot to climb. As the front drive wheels [A.3.1.] climb the step on to the next module, it tilts the robot structure slightly up thereby lifting the helical brush and it loses contact with the PV module glass. To ensure the contact with PV modules even under such conditions, strip brushes [A.2.2.] have longer bristles for higher contact length/ overlap with PV module surface. This feature also eliminates the need to provide extra length to bristles in rotary brush [A.2.1.1.], which would have demanded for higher torque to overcome the opposing friction due to increased contact and to overcome the obstruction at module to module gaps and to pull the bristles out of the inter-module space. Strip brushes [A.2.2.] ensure full coverage of module area without dead-band and also provides additional cleaning after the passage of helical brush [A.2.1.1.] in flat arrays wiping out any residual dust.

The brushes (rotary helical [A.2.1.1.] and static strip [A.2.2.]) run along the entire width of the solar array. The system cleans the entire array along with its lateral movement across the length of array without any dead-band in cleaning.

Topple safety polymer rollers [A.3.11.1.] are connected to the end bogie plates [A.1.1.1.] using clamps [A.3.11.2.] such that the roller axis is parallel to drive wheels and it projects underneath the solar PV module at a pre-determined spacing from the solar PV module frame. This safety feature is provided for preventing toppling and falling of the robot from solar PV module under overturning forces like high wind or slippage. The rollers will come into contact with the bottom side of solar PV module frame in case the robot is dislodged and prevents its fall while ensuring that there is no point load on the PV module surface.

Design of the drive wheels [A.3.1.], edge wheels [A.3.2.], middle support wheels [A.3.3.] and suspension wheels [A.3.4.1.] is customized with slotted frame to reduce weight and soft polymer coating to prevent any impact/ scratches or trails on PV module (fig 10 & 10.A.). The polymer coating is designed to have high abrasion and UV resistance to provide long outdoor operation life.

The robot [A] has lower total weight than all existing PV module cleaning robot with smart use of Aluminum, steel and plastic materials for components, while ensuring the rigidity and structural integrity.

Handles [A.1.6.] are provided at the bottom of the bogie plates [A.1.1.] connected to the bottom edge corners. It is easy to handle and manually move from array to array with this feature as it ensures that the load is transferred through the bogie plate and prevents sagging or twisting while handling.

The structure support frame [A.1.2.] is provided with length adjustment provision, by means of slot holes and multiple bolting holes on the support frame [A.1.2.]. The support frames [A.1.2.] can be pulled out or pushed in through the slots at both bogie plates [A.1.1.] accordingly. This feature makes it possible for the same robot to fit arrays with different PV modules with a length variability (standard adjustment provision is up to 50 mm, but is customizable as per requirement) (fig. 9 & 10). The helical brush [A.2.1.1.] is sized to clean maximum module length (standard design can be adjusted with respect to module length variation up to +50mm, this limit is customizable as per client requirement). The motor clamps [A.4.2.3] and [A.4.2.4.] of helical brush [A.2.1.1.] has slots to fix the motors at the desired position to pull in or push out the brush shaft [A.2.1.2.] according to the desired length adjustment. The arrangement will ensure that there are no unclean bands while extending the robot length.

The bogie plates [A.1.1.] are designed with provision for adjusting helical brush [A.2.1.1.] height. Standard offering of four slots at a gap of 5 mm are provided on the bogie plate to lower the brush position by up to 20 mm, (number of slots, slot size and total range for brush position adjustment are customizable) and ensure same level of bristle overlap with PV module glass to use the brush for longer period. This increases the usable life of the brush by four times.

Edge sensors [A.5.3.1.] to detect the end of array during the robot operation are fixed on the pre-determined position of the support frame [A.1.2.] via sensor clamps [A.5.3.3.]. Minimum of two edge sensors [A.5.3.1.] will be used per robot [A], one on each support frame [A.1.3.], to detect edges in both forward and reverse motion of the robot. More sensors can be used for redundancy, for higher lengths.

The on-board controller enclosure [A.5.1.] is connected on the controller back plate [A.5.2.]. The battery bank packaged with the battery temperature sensors, cables and power switch in the battery bank enclosure [A.6.1.]. The battery enclosure and on-board controller enclosure assembly are bolted on the support channels [A.1.3].

The robot is provided with an outer cover [A.7.] to protect the inner components like brush, wheels, controller, battery, sensors, motors, bearings etc. from direct exposure to sun and rain and to prevent the dust from flying uncontrollably during cleaning operation of the robot. The cover segments [A.7.] are connected to the bogie plates [A.1.1.] and support frame [A.1.2.].

The solar PV module [A.6.6.] for battery charging may either be integrated on the robot body [A] or it can be housed in the docking station [B] as well. If fixed on-board, the solar PV module [A.6.6.] is chosen to be light weight and flexible preferably and is fixed on to the top cover [A.7.3.] of the robot [A].

Docking & Reversing Stations:
The docking station and reversing station [B] are extensions of the PV module mounting structures of the arrays on which the robot [A] would operate. The two structures are similar except for the length of the extension and sensor guide rails, SMPS based charging unit and the optional provision for mounting PV module [C.2.] and charging unit [C.1.]. The extension rails [B.1.] and guide channels [B.2.] are longer for docking station [B.a.] in comparison to the reversing station [B.b.]. SMPS charging unit [C.3.], optional provision for charging solar PV module [C.2.] and charging unit [C.1.] is also given in docking station [B.a.]. The extension rails [B.1.] are connected to rails in PV module array structure. In case the array design is not strong to take the cantilever load due to weight of robot and docking station, an additional foundation [B.6.] and post [B.7.] are cast in the site to support the docking station [B.a.]. Two (or three, if charging solar PV module is also mounted) purlins [B.5.] are mounted on the extension rails [B.1.]. The wheel guide channels [B.2.2.] are connected across the two purlins at the top and bottom end in continuation to aluminium frame of the PV module. The sensor guide channels [B.2.1] are connected to the first purlin [B.5.] near the PV module array in line with the position of the edge sensor on the robot.

Two self-cleaning strip brushes [B.3.] are provided on docking station [B.a.] along the full length of the robot for self-cleaning of the helical brushes. The bristles of one strip brush for cleaning helical brush of robot [B.3.1.] face upwards and intercept the rotary brushes of the robots when it docks. The rotary brush is operated at full rpm at docking condition (drive motors are kept off) for cleaning the rotary brush bristles of any residual dust accumulated during the solar PV module cleaning. The second optional strip brush for cleaning the charging solar PV module mounted on robot [B.3.2.] is provided on the docking/ reversing station [B], which is mounted with bristles facing downwards and cleans the solar PV modules on the robot for self-charging the battery bank.

The system features a flexible rail design to bridge two disconnected but contiguous PV arrays. Bridge is made of a flexible link with the ends of the link fixed to the two PV module arrays on either side, which enables the bridge to absorb minor mismatch in PV array position/ angle. This arrangement is especially beneficial for tracker where interconnecting two rows from two separate trackers governed by individual controllers. In case of a tracker system, the controllers are given additional checkpoint to ensure that the tilt angle at the end of both interconnected rows, as read by inclinometers installed at the ends of each tracker rows, are matched within the acceptable angle mismatch tolerance. The acceptable tolerance of tracker angle is determined by the flexible link design, length and width as per site conditions.

Power Supply System with Provision for Dual Option Battery Charging
The robot is self-powered through battery banks [A.6.1.] (customized to suit different array lengths and duty cycles required) which is mounted on the support channels [A.1.3.] via battery clamps [A.6.3.]. The battery is charged either through solar PV module [C.2.] and MPPT charge controller [C.1.] or SMPS [C.3.]. MPPT charge controller [C.1.] is inbuilt in the onboard embedded controller [A.5.1.] and the charging solar PV module [C.2.] is mounted either on:

a. on the robot cover [A.7.] - light weight and customized - flexible solar PV modules with polymer front encapsulation or rigid solar PV modules with glass front encapsulation, which will be mounted on the moving robot body and permanently wired connection with the charging circuit;
b. mounted on docking station [B.a.] extended from the solar array; electrical connection is not permanently wired in this case; connection is made automatically/manually when the robot docks and disengaged when the cleaning cycle commences.
System is also enabled with an external charging option through SMPS charging unit [C.3.] mounted either on docking station or in the control room from 230V AC supply for fast charging or on days with low solar irradiance.

Wireless Real-time Monitoring and Control System:
Wireless monitoring and control system [D] comprises of components which are housed at different units in field and at control station as given below: a. on-board communication module (transceiver) [D.2.1.] housed in the embedded controller [A.5.1.] mounted on the robot, embedded controller of soiling measurement station [E.2.] and hand-held remote controller [D.1.1.] which can communicate to the cloud based control station [D.1.3.] or through communication gateway [D.2.2] located in the field to the SCADA control station [D.1.2.].

The system is incorporated with artificial intelligence and IoT:

a. All field devices (cleaning robots) are governed in real-time (monitored and controlled) by an onboard embedded controller and an array of sensors and I/O devices like proximity or ultrasonic edge sensors, emergency stop switches, encoders etc.
b. All field devices (cleaning robots and soiling measurement kits) are connected to centralized cloud or SCADA based controller system through wireless network in real-time. The robots can operate as per pre-programmed schedule or as per the commands from central controller or hand-held remote controller. The scheduled program in the robot’s on-board controller can be changed over the air (wireless network) from central controller.
c. The central controller is integrated with L&T’s soiling measurement station over the wireless communication network, a part of automated solar PV module cleaning system. A soiling measurement station that measures soiling loss levels in terms of the short circuit current mismatch between soiled solar PV module(s) and clean solar PV module(s) and integrated wirelessly via centralized controller on cloud or site SCADA is also provided. The central controller receives soiling loss data from all soiling measurement stations installed in the field, processes the data, compares it with the set threshold soiling level and sends activation signals to relevant individual field robots in sections of the plant where the threshold soiling level is reached. Soiling measurement stations are attached to the docking station on the PV array. The reference module is placed such that it projects outside the bottom edge of the PV array and is cleaned multiple times in a day by a wiper attached to it. The soiled sample PV module is placed along the PV array such that it is cleaned by the robot in its last cycle before docking. This arrangement quantifies the soiling level on the array and also quantifies the cleaning efficiency of the robot.
d. The proximity sensors detect edge of array and automatically stop the robot’s motion.
e. The central controller is also linked to the meteorological station in the field and receives critical data like wind speed and rainfall detection. If either of the parameter approaches or exceeds the set threshold, the field robots are switched to emergency response mode (brush motor is deactivated and drive motors operate at full speed and the robots are made to move into its docking stations).
f. The system can be linked to weather forecasting software in solar PV power plants to automatically schedule the cleaning period as per prediction for wind and rainfall conditions for the day.
g. The system can monitor the time and distance operated by each field robot and estimate failure time for the components for predictive maintenance.

Soiling Measurement Station
The soiling measurement station is comprised of two reference solar PV modules [E.1.1.] and [E.1.2.], one charging solar PV module [E.1.3.], an embedded controller [E.2.] with battery bank [E.4.] and communication module [D.2.1.].

The three solar PV modules of the soiling measurement station along with the enclosure housing the embedded controller, battery bank and communication module are fixed on the separate mounting structure [E.4.].

The above invention is operable with minimum supervision but with high reliability under all topographic conditions. The system and method is very much adaptable to existing conventional solar PV modules be in the market and also for improved versions being made currently in the market.

The system can be used for large solar rows and for smaller solar rows conveniently without any hindrance.

The invention is new and novel and in many aspects discloses the following new features which are unknown in prior art:
1. Bogie Plate with Integrated Shell Design and Belt/ Pulley arrangement:
a. Bogie integrated shell (figure 10, 10A, 10.B and 10.C): Monolithic shell-like bogie plate design for uniform load distribution and ensures rigidity of the main load carrying element under full load operation. All component housings are integrated into the design of the monolithic shell enhancing rigidity of the bogie plate and stability of housed components like bearings, shafts and other fixtures.
b. Alignment flexibility/ unique mechanical arrangement: A monolithic bogie plate each at the top and bottom edge of the robot, are bound by through shafts, making the robot move as a single solid body across its length. Both top and bottom bogie plates are fitted with edge wheels (that ride on the side frame of the solar PV modules. Edge wheels at the top are rigidly fixed with bogie plate whereas the edge wheels at the bottom are provided with suspension springs. This unique arrangement gives the robot flexibility to easily align with respect to the module misalignments in PV module frames while keeping the integrity of its structure and brush and wheel placement with respect to the PV module.
c. Specifically designed belt and pulley set for uniform torque transfer from motor to drive wheel pair each on the top and bottom bogie plates. Usage of belt and pulley in place of metal chain and sprocket, eliminates the need for lubrication and routine maintenance of the transmission unit and reduces noise. The drive wheels on each main bogie plate are connected to the drive motor through the pulley cluster and belt and receive the torque transmitted uniformly to each drive wheel.
2. Brush arrangement to ensure effective cleaning and prevention of dust accumulation, uncleaned band on PV array, AR coating damage.
a. Rotary cylindrical brush with helical winding of bristles running along the entire length of the array aids gravity in pushing the dust down from the array. Polymer bristles are specifically selected for material and size that do not cause scratches to AR coated glass of PV modules even under prolonged operation.
b. Brush design is unique with a light weight core and an outer metallic outer casing making it light weight and stiff at the same time. The design eliminates sag or eccentricity in the brush and effectively transmits the torque from the brush motor shaft across the length of the robotic cleaner.
c. The unique design of brush mounting provision on bogie plate provides option to adjust the brush height with reference to module surface allowing adjustment in the level of contact between the bristles and solar PV module glass. This provision is given for rotary brushes as well as strip brushes and helps to extend the life and durability of the brushes.
d. Two strip brushes with higher bristle length are fixed along the full length on both sides of the helical brush along the outer edge of the AMCS frame. This arrangement serves the following functions:
i. strip brush on the front removes any loose larger grits on the solar PV modules before the high speed helical brush is engaged, preventing scratches from the larger particles like small stones, twigs etc.
ii. strip brush at the back end sweeps away any remnant dust after helical brush operation.
iii. ensures brush contact with PV module surface even while robot frame is lifted off the PV module while climbing up or down a step.
e. Short strip brushes to additionally clean the band where two rotary brushes are joined.
f. Provision to add a second helical brush to intensify cleaning for customers requiring higher speed of operation or for places with severe soiling levels.
g. A strip brush is provided on docking station along the full length of the robot for self-cleaning of the helical brushes. The bristles of the strip brush face upwards and intercept the rotary brushes of the robots when it docks. The rotary brush is operated at full rpm at docking condition (drive motors are kept off) for cleaning the rotary brush bristles of any residual dust accumulated during the solar PV module cleaning.
h. The robot has the provision to add a water tank that can be connected to the through shafts, which shall be perforated at the bottom to spray water on the PV module. This arrangement can be optionally enabled if the robot is required to do water cleaning.

3. Suspension wheels designed to reduce the impact on PV module while climbing up or down a step formed by module to module misalignment: The robot is provided with a unique suspension wheel system that minimizes the impact on Aluminum frame and glass of solar PV modules. Suspension wheels and suspension assembly are provided on all four corners of the robot and both on top surface of the PV module frame (Aluminum frame surface parallel to glass surface) and on the PV module frame edge (Aluminum frame surface perpendicular to glass surface). The suspension wheels are sized to have sufficient diameter to cross module to module gap without getting stuck or without requiring any additional force from the drive motors. Suspension assembly is designed to constantly maintain contact between the suspension wheels and PV module, to absorb sudden impacts due to a drop in the surface level between two adjacent modules and to flex itself while the robot climbs the rise in surface level between two adjacent modules.
The Spring loaded bottom edge wheels always maintains contact with the bottom edge of the array and prevents skew due to lag or lead at bottom edge of robot by enabling easy adjustment of robot at locations of PV module misalignments (Fig. 10)
4. Integrated soiling loss measurement station: A soiling measurement station that measures soiling loss levels in terms of the short circuit current mismatch between a soiled and clean solar module and integrated via centralized controller on cloud or site SCADA is also provided. The soiling measurement station can detect soiling loss as low as 0.5%, high accuracy is achieved with the carefully selected and tested shunt current sensors. The soiling measurement station is enabled with wireless communication technology compatible with the power plant layout to communicated monitoring and control signals to and from remote control portal on cloud/SCADA. In addition to activation of the cleaning robot as per pre-scheduled routine cleaning time and manual control signals from central control station/remote controller, the cleaning routine can be initiated as per the cleaning initiation command from the cloud control portal when the soiling loss measured by the soiling measurement station exceeds the preset threshold levels; the latter two commands can over-ride the pre-scheduled cleaning routine. Integration with soiling loss measurement station enables to optimize cleaning routine with respect to real time, on-field soiling loss levels and helps to keep soiling loss within threshold levels.
Soiling measurement stations are attached to the docking station on the PV array. The reference module is placed such that it projects outside the bottom edge of the PV array and is cleaned multiple times in a day by a wiper attached to it. The soiled sample PV module is placed along the PV array such that it is cleaned by the robot during every cycle of its operation as it passes over to docking station. This arrangement quantifies the soiling level on the array and also quantifies the cleaning efficiency of the robot.
5. Provision to adjust length of the robot to fit different solar PV module sizes: solar PV modules of different manufacturers can vary in dimensions. The cleaning robot (AMCS) design has the provision to adjust its length, if required, so that same equipment can be used to fit solar PV modules with size variation in a plant. The bogie plate, side support frames and brush shafts have been designed with length adjustment slots to enable end to end cleaning of solar PV modules within the allowed length variations. The feature can also be implemented with sliding grooves and bolting on the components.
6. Modular design: The robot structure is modular with segmented structure components and brushes for variable length. Modular sections (preferably 2m long lattice modules, can be customized for other lengths too) can be repeated and easily inter-connected with intermediate middle bogie assembly (figure 10B & 10C) to create robots of higher lengths. Modularity in design offers the following advantages:
a. Easy to appropriately assemble for use with trackers, seasonal tilt and fixed tilt structures with the same design components
b. suitable for fitting landscape and portrait mounted PV modules.
c. Variants of different lengths in multiples of base unit, can be easily customized as per array layout
d. compatible for structure arrangements both with or without support member for wheels; eliminates need for any additional support member and can be deployed in new or existing solar power plants with minimal retrofitting.
e. Adjustable length to cater to dimension differences from module to module
f. Ease of manufacturing and assembly
7. Uniform load distribution on solar PV modules and load sharing between wheels: The wheels of the robotic cleaner move on the Aluminum frame of solar PV module which prevents the transfer of load to the glass and underlying solar PV cells. Sufficient number of wheels are placed on the top and side edges of the Aluminum frame per robot system to divide the total load and minimize load at any point on the PV module frame. The load transfer on the Aluminum frame is designed to be much lower than the threshold load capacity of the Aluminum frame estimated based on section modulus and yield strength of the Aluminum frame of PV modules. Wheel width is designed to further reduce point loads. Base of drive and suspension wheels that run on the top frame of PV modules, is at least 10 mm wider than the Aluminum frame width on the top of PV module and has a minimum 5mm overhang on either side of the PV module frame while operating. This ensures that the wheel always runs on top of the frame and not on glass surface of solar PV modules. For lengths higher than 2m, intermittent wheels are provided at every 2m along with the middle bogie plate, to further distribute the load transfer evenly on the solar PV module frame.
8. Skew correction mechanism: The system which is a combination of the following design elements to operate the robot without any skew and for uniform torque delivery to all drive wheels.
a. The drive mechanism consists of separate DC motors at the top bogie and bottom bogie to deliver equal torque/power at top and bottom end of the robot and ensure uniform torque delivery and motion by coupling the drive wheel sets on top and bottom to the corresponding motor through a set of pulleys and belts respectively.
b. Encoders at each drive motor give feedback to the controller to adjust speed of each motor independently and prevent skew between top and bottom bogies of the cleaning robot of AMCS.
c. The drive wheels at each section (top edge or bottom edge) are connected to the corresponding motor through an arrangement comprising of pulleys and belt which uniformly delivers torque to each drive wheel. Thus all drive wheels are uniformly powered, making the motion of the robot smooth.
d. The wheel diameter and motor rating are sized such that the robot can cross over module to module gaps acceptable as per industry requirement (standard up to 30 mm, customizable as per specific project site conditions) and to climb over steps or module misalignments acceptable as per industry requirement (standard up to 20mm, customizable as per specific site conditions) without any additional support or structure. The ratio of height of step to wheel radius is optimized to minimize the oversizing requirement of motor power and the ratio of module to module gap to wheel radius should be greater than 1:1.15.
e. Edge wheels at the bottom bogie plate is provided with individual spring suspension assembly to maintain continuous contact with PV array edge throughout navigation which expand and contract while climbing up or down a step and provide length correction and flexibility to navigate smoothly without any skew or getting stuck.
The combination of the above features allow the robot to smoothly navigate over misaligned PV module arrays with ease and minimal energy consumption.

9. The system features a flexible rail design to bridge two disconnected but contiguous PV arrays. Bridge is made of a flexible link with the ends of the link fixed to the two PV module arrays on either side, which enables the bridge to absorb minor mismatch in PV array position/ angle. This arrangement is especially beneficial for tracker where interconnecting two rows from two separate trackers governed by individual controllers. In case of a tracker system, the controllers are given additional checkpoint to ensure that the tilt angle at the end of both interconnected rows, as read by inclinometers installed at the ends of each tracker rows, are matched within the acceptable angle mismatch tolerance. The acceptable tolerance of tracker angle is determined by the flexible link design, length and width as per site conditions

The invention relates to a PV module cleaning system for cleaning the solar PV modules. It has a robot which has a frame having the components arranged thereon. It includes a pair of monolithic shell like bogie plate one at the top edge and another at the bottom edge and bound together with shafts and said bogie plates have length adjustment slots, drive wheels, edge wheels and suspension wheels that are arranged on the bogie plate, with edge wheels on the top bogie plate rigidly fixed and edge wheels on the bottom bogie plate having suspension springs, said edge wheels ride on the side frame on the solar PV modules, said spring loaded bottom edge wheels ensure contact with bottom edge of the array and prevent skew due to lag or lead at bottom edge of robot, drive wheels that are fixed on the bogie plate and are powered by drive motors and ride on the top edge of solar PV module Aluminium frame and suspension assembly mounted on bogie plate. A custom designed belt and pulley arrangement with motor will drive the said drive wheels, to provide uniform torque on each of the drive wheels. The brush arrangement comprises of a rotary cylindrical brush with helical winding of polymer bristles also referred to as helical brush, running along the entire length of the array, said brushes are attached to brush shafts having height adjustable slots, two long strip brushes along the full length on both sides of the helical brush along outer edge of the frame, and said brushes are attached to brush shafts having height adjustable slots, and two short strip brushes at the junction point of rotary brushes, the said brushes are attached to brush shafts having height adjustable slots. The system also includes suspension wheels in a custom designed spring suspension assembly arranged on four corners of the robot, on top surface of PV module frame, and on the PV module frame edge, with diameter of suspension wheels which are sufficient to cross module to module gap, and the spring and arm arrangement designed to constantly maintain contact between the suspension wheels and PV module while moving on flat surfaces or while climbing up or down a step. The invention features an intelligent operation with a real-time monitoring, feedback and control mechanism comprising of a powerful onboard embedded controller powered by an onboard solar powered battery bank, deriving and delivering real-time feedback and control signal from an array of onboard sensors (edge/position/emergency switches/ encoders etc.) and from a centralized controller (hosted on cloud or SCADA) via real time wireless communication. The system is comprised of integrated soil loss measurement stations which are further attached to the docking station of the PV array and gives feedback on the effectiveness of cleaning/ soiling loss level as a trigger to initiate cleaning.

In one aspect as described above the invention relates to a solar PV module dry cleaning system for cleaning the solar panels which has a set of mobile wheeled robots for cleaning the solar PV panel arrays, docking stations extended from solar PV panel array to berth the robot in between cleaning cycles, reversing stations extended from the opposite end of solar PV panel array to reverse the robot direction, embedded controllers on said robots, remote controller platform and wireless communication system for automation and real time monitoring and control; charging units to charge the battery bank that powers the robot and soiling loss measurement station to measure the soiling level of the PV array. It has a robot having number of wheels comprising of at least four drive wheels, at least two edge wheels, suspension wheels and middle support wheels. The robot is supported on a modular base frame, having a set of monolithic shells called bogie plates - one at the top edge and another at the bottom edge of each modular section of the robot frame - which are interconnected and bound together with shafts and said bogie plates having length adjustment slots to adjust the length of robot with respect to solar PV module length variations. The edge wheels are arranged on the bogie plates, with edge wheels on the top bogie plate rigidly fixed and edge wheels on the bottom bogie plate having suspension springs, said edge wheels ride on the side frame on the PV panels, said spring loaded bottom edge wheels ensure contact with bottom edge of the array and prevent skew due to lag or lead at bottom edge of robot. The drive wheels of the robot are also associated with a corresponding belt and pulley arrangement housed on the bogie plates driven by motors associated with corresponding feedback encoders to power the drive wheels of the robot, to provide uniform torque on each of the drive wheels. There are more than one type of brush used in this system. Firstly, there is a rotary cylindrical brush which is mounted on the said robot and between the said bogie plates and said brush having helical winding of polymer bristles running along the entire length of the array, and these rotary brushes are attached to brush shafts having length adjustable slots and associated with slots on bogie plates for height adjustment of the said brush. The second set is of two long length strip brushes arranged along with the full length on both sides of the helical brush and mounted along the outer edge of the robot base frame and associated with slots on the said frame for height adjustment of the said brush. The third set is of two short length strip brushes mounted around the junction point of rotary brushes and associated with slots on the said frame for height adjustment of the said brush. The system further has a set of at least four suspension assemblies arranged on four corners of the said robot, and each assembly having at least two suspension wheels moving on top surface of solar PV module frame and on the PV module frame edges, with diameter of each suspension wheel adapted based on the module-to-module gap and for crossing the module gaps by constantly maintaining contact between the suspension wheels and solar PV modules with a combination of lever and spring arrangement. The system further has a flexible link with its two ends fixed to two adjacent PV module arrays on either side forming a bridge for the motion of the said robot. The system is associated with an integrated soiling loss measurement station to measure real time soiling loss in solar PV array and which is further attached to the docking station on the solar PV array and adapted to digitally transmit input signals to the said robot regarding soiling loss measurement values.
As detailed above and disclosed the product as such as a whole is unique with distinguishing factors explicitly disclosed and defined for the working of this invention.
It is to be understood that invention is not limited to embodiments described or illustrated herein but includes any and all modifications which are obvious to skilled persons in the art.
The applicant relies upon the provisional specification and drawings filed in this application and shall be considered as part and parcel of complete specification.
,CLAIMS:WE CLAIM:
1. A solar PV module dry cleaning system for cleaning the solar PV modules which has a set of mobile wheeled robots for cleaning the solar PV module arrays, docking stations extended from solar PV module array to berth the robot in between cleaning cycles, reversing stations extended from the opposite end of solar PV module array to reverse the robot direction, embedded controllers on said robots, remote controller platform and wireless communication system for automation and real time monitoring and control; charging units to charge the battery bank that powers the robot and soiling loss measurement station to measure the soiling level of the PV array, and comprising of:
- a robot having plurality of wheels comprising of at least four drive wheels, at least two edge wheels, suspension wheels and middle support wheels,
- said robot supported on a modular base frame, having a set of monolithic shells called bogie plates - one at the top edge and another at the bottom edge of each modular section of the robot frame - which are interconnected and bound together with shafts and said bogie plates having length adjustment slots to adjust the length of robot with respect to solar PV module length variations,
- said edge wheels arranged on the bogie plates, with edge wheels on the top bogie plate rigidly fixed and edge wheels on the bottom bogie plate having suspension springs, said edge wheels ride on the side frame on the solar PV modules, said spring loaded bottom edge wheels ensure contact with bottom edge of the array and prevent skew due to lag or lead at bottom edge of robot,
- said drive wheels of the robot are associated with a corresponding belt and pulley arrangement housed on the bogie plates driven by motors associated with corresponding feedback encoders to power the drive wheels of the robot, to provide uniform torque on each of the drive wheels,
- a rotary cylindrical brush, mounted on the said robot and between the said bogie plates and said brush having helical winding of polymer bristles running along the entire length of the array, said brushes are attached to brush shafts having length adjustable slots and associated with slots on bogie plates for height adjustment of the said brush,
- two long length strip brushes along the full length on both sides of the helical brush mounted along the outer edge of the robot base frame and associated with slots on the said frame for height adjustment of the said brush,
- two short length strip brushes mounted around the junction point of rotary brushes and associated with slots on the said frame for height adjustment of the said brush,
- a set of at least four suspension assemblies arranged on four corners of the said robot, and each assembly having at least two suspension wheels moving on top surface of solar PV module frame and on the PV module frame edges, with diameter of each suspension wheel adapted based on the module-to-module gap and for crossing the module gaps by constantly maintaining contact between the suspension wheels and solar PV modules with a combination of lever and spring arrangement,
- a flexible link with its two ends fixed to two adjacent PV module arrays on either side forming a bridge for the motion of the said robot, and
- an integrated soiling loss measurement station to measure real time soiling loss in solar PV array and which is further attached to the docking station on the solar PV array and adapted to digitally transmit input signals to the said robot regarding soiling loss measurement values.
2. The PV module dry cleaning system for cleaning the solar PV modules as claimed in claim 1 is such that the ratio of wheel radius is basis on the ratio of PV module to PV module gap to drive wheel radius is greater than 1:1.15.