Description:FIELD OF INVENTION :

Inventions related to modular bifacial solar tracking system suitable for floating PV.

BACKGROUND OF THE INVENTION :

A horizontal single axis East-West tracker is popular globally as it offers lower price to performance ratio over conventional fixed mount structures and other types of sun-tracking structures. The technology has been widely used for ground-based projects but its use on floating PV projects has been nil so far because of complexity associated with engineering of the design and construction challenges of tracking plant on moving base which is typical characteristics of any water body e.g. ponds, lakes, reservoirs, dams, rivers or ocean. Conventional fixed tilt floating PV structures are designed to provide lower tilt angle, small to no air passage on rear side of the modules and has very high ground coverage ratio, which may be suitable for traditionally manufactured mono-facial solar PV modules but highly unfit for bifacial solar PV modules as it results into compromised energy generation and almost nullifies any useful energy generation from rear side of bifacial solar modules.

PRIOR ART :

Few prior art documents are discussed herein:-

D1 – WO 2020/198618 A1 – Floating Solar Tracker

Systems are described herein to include a floating solar tracker. A floating solar tracker includes solar modules, a mechanical structure, and a floating structure. The solar modules are supported by mechanical structure that is secured to floating structure. The floating structure can be a pontoon-like structure that includes a pair of hollow cylinders. The hollow cylinders can be cylinder structures having a positive buoyancy to facilitate floating on a body of water. The mechanical structure can be secured to floating structure via an anchor band. In some variations, a reflective material can be stretched on top of the floating structure to maximize the amount of light reflected back to the solar modules.

D2 – WO 2016/185267 A1 – Floating Solar Power Plant

The present invention is directed towards a floating solar power plant. A floating Y-shaped module is a basic building block for the floating solar power plant. The Y-shaped structure have the three arms which are radiating outwardly from a central point, wherein the free ends of the arms have one or more coupling means. The Y-shaped module is interconnected to produce a hexagonal space grid structure to support the solar modules. The solar modules are mounted with the help of mounting structures on the hexagonal space grid structure. The hexagonal space grid structure is enclosed in a floating enclosure to minimize the effect of the water waves on the solar power plant. The floating enclosure is also anchored to restrict the movement of the floating solar power plant. The floating solar power plant is further configured with a positioning system, altitude tracking controllers, propellers, and pneumatic structures.

D3 – US 2017/0040926 A1- Floating solar module array with one-axis tracking system

A floating solar array made of a closed loop of flexible high density polyethylene pipes with elbows, T fittings and couplings. An anti-lift membrane fills with water and mitigates the wind forces. The array can have a stabilizing skirt going downwardly from the border of the array, especially when it is used offshore in the sea. A vertical axis tracking system with windlasses, two anchoring points and four mooring lines allows all the solar modules to face the sun throughout the day. For small lakes or mine tailing, the two anchor points will be onshore, on a concrete foundation. Winches to wind and unwind the mooring lines are located at the anchor point or on the solar array. For larger water areas, or offshore applications in the sea water, the anchor points are under water; using typically a concrete block or a suction pile solution for each anchor.

D4- WO 2010/026542 A4- Apparatus and method for generating electricity using photovoltaic modules

An apparatus for generating electricity using photovoltaic modules comprises a module mounting structure adapted to position the modules in a body of water in such a way that the top face of the modules designed to receive the solar radiation are operatively covered by a layer of water of predetermined depth. A method for generating electricity using photovoltaic modules comprises preparing a module mounting structure and positioning the structure in a body of water in such a way that the top faces of the modules designed to receive the solar radiation are operatively covered by a layer of water of predetermined thickness.

D5-US 2008/0302357 A1- Solar photovoltaic collector hybrid

The present invention discloses a system for a hybrid solar energy collector comprising a CIGS photovoltaic energy collector, the photovoltaic energy collector being thermally coupled to an energy absorbing working fluid casing for flowing heat out to heat sink The solar radiation is trapped in the photovoltaic collector, generating electrical power from the CIGS photovoltaic array, The array is cooled by the working fluid transferring unproductive heat away from the photovoltaic array and into an exterior heat sink via the cooling fluid circuit, thus making the photovoltaic array more efficient, while adding another energy source. Where thermal collection is not beneficial, a floating platform supported CIGS PV array may be cost effectively cooled to increase efficiency, by harnessing wave energy from a wave power device to flow cooling or evaporative spray water over the module.

D6- US 2015/0357969 A1 – Cooling method and system for photovoltaic solar modules

The present invention relates to a cooling system and method for photovoltaic solar modules. The cooling system and method allow reducing the temperature of the outer surface of photovoltaic solar modules, thereby maximizing their performance, and keeping their surface at optimal operating temperatures (about 25° C.) at all times, while at the same time allowing cleaning and eliminating dust and/or fouling residues on said surface, even further optimizing, if possible, the total performance of said PV modules (2).

OBJECTIVE OF THE INVENTION :

The present invention overcomes limitations of conventional low-tilt fixed type or azimuthal solar tracking system by employing horizontal tracking system coupled with solar reflectors and wave impact mitigation systems which makes our invention highly suitable for floating PV plants with bifacial PV modules.

BRIEF DESCRIPTION OF DRAWINGS :

Figures:

Fig 1a. Floating PV Solar Tracker
Fig 1b. Slew Drive Assembly
Fig 2. Anchoring and Mooring System
Fig 3. Scalability/ Plurality of the Floating Tracker System
Fig 4. Vertical Post and Float Pattern Arrangement
Fig 5. Metal Grateway Arrangement in the E-W and the N-S Directions
Fig 6a. Optical Reflector Arrangement
Fig 6b. Wire Rope Support for Reflectors
Fig 7. Cooling System

SUMMARY OF THE INVENTION :

The proposed system aims to construct horizontal single axis tracking system compatible for bifacial PV module installation for water bodies to offer optimum energy gain with the help of a) module horizontal single axis solar tracker structure system with innovative wave impact mitigation system, b) solar reflectors for enhanced bifacial gain, and c) optionally a cooling system which minimizes thermal and soiling losses and therefore minimizes maintenance requirements.

In one aspect, a horizontal single axis (E-W) tracker, the mechanical structure designed to install plurality of solar photovoltaic modules and a floating structure designed to float on the water bodies.

In some variation, mechanical structure is designed to be modular wherein each unit structure is characterized as the mechanical structure arrangement between two vertical posts in N-S direction and float structure arrangement in E-W direction between two consecutive rows. One such unit may host a few kWs of solar PV system and repetition of many such modules in N-S and E-W direction results in desired capacity of the solar PV system from a few kW to utility scale project.

In another variation, the mechanical structure is connected to the floating structure and modularity of the mechanical structure and floating structure offers it the scalability right from few kW to utility scale projects.

In yet another variation, the torque tube is rotated through slewing drive coupled to single or plurality of solar tracker rows, whereas rotation of torque tube results in rotation of plurality of solar modules.

In one aspect, the solar PV panels are mounted on torque tube through specially design hat rails. The hat rails position solar PV panels at sufficient height above torque tube to avoid shading of torque tube on rear side of PV panels and maximize bifacial gain.

In one aspect, torque tube is connected to the vertical support structure (vertical post) through universal coupler arrangement to provide immunity against stress, twisting and bending forces etc. which otherwise could have impacted torque tube on account of wave motion of water body.
In one aspect, slewing drive provides necessary torque for moving radial or axial loads. It is powered by an electric motor with NREL tracking algorithms integration for controlled rotation of slew drive led to rotation of holding torque tube with modules.

In another variation, hydraulic dampers are employed to reduce the intensity of galloping and in turn reduce risk of damage to the torque tube, tracker structure and solar panels.

In one aspect, float structure is made of plurality of floats connected with one another through ears or connection points. Different types of floats with different buoyancy which are designed for different applications are employed for connecting mechanical structures, for carrying power cables and water pipeline, for walkway, for supporting solar reflective system, for breaking wave power for mounting pumps, weather monitoring system, string combiner boxes or for functioning as spacers and interconnecting floats in NS and EW direction etc.

In one aspect, the double layered polymer / metal grate walkway ensures spacing as per pitch requirement pitch between two consecutive rows along the E-W directions.

In some variation, single layered polymer / metal grate walkways in N-S directions connected between two consecutive vertical posts along the N-S direction maintains necessary distance and resists any bending forces which may otherwise act upon torque tube. Together, they facilitate movement of persons or transportation of materials inside the floating PV plant.

In one aspect, plurality of floats is connected to the spreader bar and in turn to the mooring and anchoring system.

In one aspect, plurality of reflector sheets 640 positioned at lower height than solar PV module constitutes reflective system.

In another variation, reflector sheets 640 are made of reflective material glued or painted onto the flexible or rigid substrate. Plurality of wires or rigid support and are connected with the vertical support structure. The solar reflective system covers foot-print and areas in between tracker rows. The reflective materials offer higher albedo than offered by water and it can be configured to increase sun-light intensity on rear and front side of PV module.

In one aspect, plurality of water sprinkler nozzles, control valves, pumps, water inlet, pipeline network, water filters and temperature sensors along with wired or wireless communication network constitutes cooling system. The sprinklers are mounted along with vertical posts, which releases water for preset temperature difference between inlet and solar PV module till temperature difference achieves preset value. Frequent sprinkling of water serves dual purpose of cleaning of plurality of reflector sheets 640 and plurality of solar PV modules.

In another aspect, plurality of solar radiation sensors and wind speed sensors, data loggers, temperature sensors will provide data to plurality of tracker control system help tracking the sun, with higher accuracy. The plurality of controllers provide signals for various events e.g. back-tracking, stow mode, cloud mode, rain and emergency mode features.

DETAILED DESCRIPTION OF THE INVENTION :

The present invention is now described in detail herein :

TABLE – 1: Key differentiators between “D1” a known prior art disclosed herein and present tracker for floating PV

Sr No Feature Article Proposed System
1 Structure arrangement Modules are supported with inverted “V” shaped inclined support structure, both the legs are connected on two separate floats. Module are supported through hat rails over rotatable tube through which, it is connected on single vertical post located at fix interval mounted on suitable floating platform
2 Tracker Horizontal Single Axis Block Tracker with circular rack and pinion type arrangement.
Plurality of trackers coupled with drive shaft run by motor Horizontal Single Axis Row Tracker with worm and worm-wheel powered drive.
Individual drive for each row coupled with torque tube and drive
3 Floats Pair of hollow cylinders provide necessary positive buoyancy to entire structure atop. Comprises of sealing mechanism to avoid water entry. Floating platform is made with high density polymer material, it can be cuboid, rectangular or of any suitable shape, which is prefilled with filler material, so no possibility of leakage and water entry. It has supporting linings strengthening members at regular interval to provide necessary structure strength and rigidity. It also has ears for providing connection points with one another, with metal structure on top and mooring lines.
4 Reflector arrangement No separate reflector member, cylindrical hollow floats are covered with reflective plastic material which is stretched on top side. Reflectors are made of reflective film attached on hard or flexible substrate and supported at regular interval through metal wire or hard substrate and connected with the tracker structure at vertical support structure member. The reflectors cover module foot print and also gap between two tracker rows completely or partially. The reflectors are tilted towards their respective directions i.e. reflector on the East of module is tilted towards the East and vice versa. Tilting of reflector avoid water accumulation on top and gets cleaned itself every-time water from sprinkler is sprayed over modules.
The reflector material may also be painted on light weight floats between the tracker row gap and two vertical posts along the length of the tracker.
5 Pipe and Sprinklers for cleaning 2 module in portrait configuration is mentioned. Modules are separated by central purlin. Simple arrangement of two sets of sprinklers, one sprinkler for one module each, sprinklers are located on either sides of central purlin and caters to respective modules. LNT design involves smart cooling system in which frequency and duration of water spray is controlled through solenoid valve and programmable controller. The controller opens sprinklers either at fixed time interval e.g. after every 10 seconds or upon reaching preset temperature delta between inlet water and module temperature.
Further, out of many water inlets, controller selects the coolest water inlet to maximize cooling impact.
Moreover, one sprinkler per vertical support structure is sufficient to cover all the modules upto second vertical support structure.
The sprinklers are mounted on torque tube, outlet of sprinkler is at higher level than solar PV module surface and sprinkler rotates with the torque tube with necessary rotary coupling and flexible pipes. This arrangement ensures that water is only sprayed on front side of the PV module even while modules are tracking the sun.
Further sprinkler is mounted sufficiently away from solar PV module edge to cast any significant shading on solar PV module surface.
6 Float to mechanical structure interconnection Mechanical structure is secured to float structure via one or more anchor bands of relatively large diameter compared to cylindrical floats. Float to mechanical structure connection is through base plate at the bottom of the vertical support structure and anchor plate bolted on the floats. In which, anchor plate is connected with the float via through and through bolts or directly on the ears of the one large float or four smaller floats connected at common point through ears. It can also be achieved through metal flats wrapped around the float and bolted with the anchor plate of the vertical post.
7 Float to float interconnection Not Mentioned Floats are interconnected with one another through polymer pin inserted into ears of adjoining floats or through suitable long linear metal section at the bottom.

TABLE – 2: Key differentiators between “D2” a known prior art disclosed herein and present tracker for floating PV

Sr No Feature Article Proposed System
1 Tracking Mechanism Vertical Single Axis Azimuth Tracker Horizontal Single Axis Row Tracker with worm and worm-wheel powered drive. Individual drive for each row coupled with torque tube and drive
2 Propulsion System Propulsion system coupled with hierarchical hexagonal float arrangement for azimuth movement No propulsion system required, drives provide required torque for modules to rotate along the Sun in the EW direction.
2 Structure Posts Not Mentioned Module are supported through hat rails over rotatable tube through which, it is connected on single vertical post located at fix interval mounted on suitable floating platform
4 Reflectors Not Mentioned Reflectors are made of reflective film attached on hard or flexible substrate and supported at regular interval through metal wire or hard substrate and connected with the tracker structure at vertical support structure member. The reflectors cover module foot print and also Gap between two tracker rows completely or partially. The reflectors are tilted towards their respective directions i.e. reflector on the East of module is tilted towards the East and vice versa. Tilting of reflector avoid water accumulation on top and gets cleaned itself every-time water from sprinkler is sprayed over modules.
The reflector material may also be painted on light weight floats between the tracker row gap and two vertical posts along the length of the tracker.
5 Pipe and Sprinklers for cleaning Not Mentioned LNT design involves smart cooling system in which frequency and duration of water spray is controlled through solenoid valve and programmable controller. The controller opens sprinklers either at fixed time interval e.g. after every 10 seconds or upon reaching preset temperature delta between inlet water and module temperature.
Further, out of many water inlets, controller selects the coolest water inlet to maximize cooling impact.
Moreover, one sprinkler per vertical support structure is sufficient to cover all the modules upto second vertical support structure.
The sprinklers are mounted on torque tube, outlet of sprinkler is at higher level than solar PV module surface and sprinkler rotates with the torque tube with necessary rotary coupling and flexible pipes. This arrangement ensures that water is only sprayed on front side of the PV module even while modules are tracking the sun.
Further sprinkler is mounted sufficiently away from solar PV module edge to cast any significant shading on solar PV module surface.

TABLE – 3: Key differentiators between “D3” a known prior art disclosed herein and present tracker for floating PV

Sr No Feature Article Proposed System
1 Tracker Fixed tilt modules with vertical single axis tracker with the help of winches and mooring lines connected with plurality of solar arrays Horizontal Single Axis Row Tracker with worm and worm-wheel powered drive.
Individual drive for each row coupled with torque tube and drive
2 Structure Posts Not Mentioned Module are supported through hat rails over rotatable tube through which, it is connected on single vertical post located at fix interval mounted on suitable floating platform
3 Floaters Cylindrical hollow pipes, connected in row and column array, to form square and rectangular areas and then to hexagonal area as close loop array Floating platform is made with high density polymer material, it can be cuboid, rectangular or of any suitable shape, which is prefilled with filler material, so no possibility of leakage and water entry. It has supporting linings strengthening members at regular interval to provide necessary structure strength and rigidity. It also has ears for providing connection points with one another, with metal structure on top and mooring lines.
4 Reflectors Not Mentioned Reflectors are made of reflective film attached on hard or flexible substrate and supported at regular interval through metal wire or hard substrate and connected with the tracker structure at vertical support structure member. The reflectors cover module foot print and also gap between two tracker rows completely or partially. The reflectors are tilted towards their respective directions i.e. reflector on the East of module is tilted towards the East and vice versa. Tilting of reflector avoid water accumulation on top and gets cleaned itself every-time water from sprinkler is sprayed over modules.
The reflector material may also be painted on light weight floats between the tracker row gap and two vertical posts along the length of the tracker.
5 Pipe and Sprinklers for cleaning Not Mentioned LNT design involves smart cooling system in which frequency and duration of water spray is controlled through solenoid valve and programmable controller. The controller opens sprinklers either at fixed time interval e.g. after every 10 seconds or upon reaching preset temperature delta between inlet water and module temperature.
Further, out of many water inlets, controller selects the coolest water inlet to maximize cooling impact.
Moreover, one sprinkler per vertical support structure is sufficient to cover all the modules upto second vertical support structure.
The sprinklers are mounted on torque tube, outlet of sprinkler is at higher level than solar PV module surface and sprinkler rotates with the torque tube with necessary rotary coupling and flexible pipes. This arrangement ensures that water is only sprayed on front side of the PV module even while modules are tracking the sun.
Further sprinkler is mounted sufficiently away from solar PV module edge to cast any significant shading on solar PV module surface.

TABLE – 4: Key differentiators between “D4” a known prior art disclosed herein and present tracker for floating PV

Sr No Feature Article Proposed System
1 Tracking Mechanism Fixed tilt modules with vertical single axis tracker with the help of winches and mooring lines connected with plurality of solar arrays. Also tracking parallel to water surface by keeping fixed angle to water surface. Horizontal Single Axis Row Tracker with worm and worm-wheel powered drive.
Individual drive for each row coupled with torque tube and drive
2 Structure Posts Not Mentioned Single Vertical post located at fix interval resting on set of multiple floaters
3 Floats Not Mentioned Floating platform is made with high density polymer material, it can be cuboid, rectangular or of any suitable shape, which is prefilled with filler material, so no possibility of leakage and water entry. It has supporting linings strengthening members at regular interval to provide necessary structure strength and rigidity. It also has ears for providing connection points with one another, with metal structure on top and mooring lines.
4 Reflectors Not Mentioned Reflectors are made of reflective film attached on hard or flexible substrate and supported at regular interval through metal wire or hard substrate and connected with the tracker structure at vertical support structure member. The reflectors cover module foot print and also gap between two tracker rows completely or partially. The reflectors are tilted towards their respective directions i.e. reflector on the East of module is tilted towards the East and vice versa. Tilting of reflector avoid water accumulation on top and gets cleaned itself every-time water from sprinkler is sprayed over modules.
The reflector material may also be painted on light weight floats between the tracker row gap and two vertical posts along the length of the tracker.
5 Cooling Modules are submerged in the water surface with specific controlled depth by controller LNT design involves smart cooling system in which frequency and duration of water spray is controlled through solenoid valve and programmable controller. The controller opens sprinklers either at fixed time interval e.g. after every 10 seconds or upon reaching preset temperature delta between inlet water and module temperature.
Further, out of many water inlets, controller selects the coolest water inlet to maximize cooling impact.
Moreover, one sprinkler per vertical support structure is sufficient to cover all the modules upto second vertical support structure.
The sprinklers are mounted on torque tube, outlet of sprinkler is at higher level than solar PV module surface and sprinkler rotates with the torque tube with necessary rotary coupling and flexible pipes. This arrangement ensures that water is only sprayed on front side of the PV module even while modules are tracking the sun.
Further sprinkler is mounted sufficiently away from solar PV module edge to cast any significant shading on solar PV module surface.

TABLE – 5: Key differentiators between “D5” a known prior art disclosed herein and present tracker for floating PV

Sr No Feature Article Proposed System
1 Tracker Not Claimed Horizontal Single Axis Row Tracker with worm and worm-wheel powered drive.
Individual drive for each row coupled with torque tube and drive
2 Structure Posts Not Claimed Single Vertical post located at fix interval resting on set of multiple floaters
4 Reflectors Not Claimed Reflectors are made of reflective film attached on hard or flexible substrate and supported at regular interval through metal wire or hard substrate and connected with the tracker structure at vertical support structure member. The reflectors cover module foot print and also gap between two tracker rows completely or partially. The reflectors are tilted towards their respective directions i.e. reflector on the East of module is tilted towards the East and vice versa. Tilting of reflector avoid water accumulation on top and gets cleaned itself every-time water from sprinkler is sprayed over modules.
The reflector material may also be painted on light weight floats between the tracker row gap and two vertical posts along the length of the tracker.
5 Cooling The array is cooled by the working fluid transferring unproductive heat away from the photovoltaic array and into an exterior heat sink via the cooling fluid circuit. LNT design involves smart cooling system in which frequency and duration of water spray is controlled through solenoid valve and programmable controller. The controller opens sprinklers either at fixed time interval e.g. after every 10 seconds or upon reaching preset temperature delta between inlet water and module temperature.
Further, out of many water inlets, controller selects the coolest water inlet to maximize cooling impact.
Moreover, one sprinkler per vertical support structure is sufficient to cover all the modules upto second vertical support structure.
The sprinklers are mounted on torque tube, outlet of sprinkler is at higher level than solar PV module surface and sprinkler rotates with the torque tube with necessary rotary coupling and flexible pipes. This arrangement ensures that water is only sprayed on front side of the PV module even while modules are tracking the sun.
Further sprinkler is mounted sufficiently away from solar PV module edge to cast any significant shading on solar PV module surface.

TABLE – 6: Key differentiators between “D6” a known prior art disclosed herein and present tracker for floating PV

Sr No Feature Article Proposed System
2 Tracker Not Claimed Horizontal Single Axis Row Tracker with worm and worm-wheel powered drive.
Individual drive for each row coupled with torque tube and drive
4 Reflectors Not Claimed Reflectors are made of reflective film attached on hard or flexible substrate and supported at regular interval through metal wire or hard substrate and connected with the tracker structure at vertical support structure member. The reflectors cover module foot print and also gap between two tracker rows completely or partially. The reflectors are tilted towards their respective directions i.e. reflector on the East of module is tilted towards the East and vice versa. Tilting of reflector avoid water accumulation on top and gets cleaned itself every-time water from sprinkler is sprayed over modules.
The reflector material may also be painted on light weight floats between the tracker row gap and two vertical posts along the length of the tracker.
5 Cooling The fluid sprayers (are located on an elongated common rod installed along the upper edge of the PV modules.
Characterized in that the fluid sprayers are sprinklers, micro sprinklers, drip sprayers, sheet sprayers or the like.
Characterized in that the electric pump is a combined, lift-force pump. LNT design involves smart cooling system in which frequency and duration of water spray is controlled through solenoid valve and programmable controller. The controller opens sprinklers either at fixed time interval e.g. after every 10 seconds or upon reaching preset temperature delta between inlet water and module temperature.
Further, out of many water inlets, controller selects the coolest water inlet to maximize cooling impact.
Moreover, one sprinkler per vertical support structure is sufficient to cover all the modules upto second vertical support structure.
The sprinklers are mounted on torque tube, outlet of sprinkler is at higher level than solar PV module surface and sprinkler rotates with the torque tube with necessary rotary coupling and flexible pipes. This arrangement ensures that water is only sprayed on front side of the PV module even while modules are tracking the sun.
Further sprinkler is mounted sufficiently away from solar PV module edge to cast any significant shading on solar PV module surface.

i). HORIZONTAL SINGLE AXIS FLOATING TRACKER STRUCTURE

The horizontal single axis E-W solar tracker for floating PV system, constituted of plurality of structure units (modules) which are inter-connected in required numbers to constitute desired size of the tracker rows. The tracker row runs along the N-S direction which comprises of plurality of torque tubes, hat-rails, vertical posts, base plates, and the plurality of solar PV panels. Solar PV panels are mounted on the central rotating torque tube through the plurality of hat-rails.

The torque tubes are connected to the vertical support structure through plurality of universal couplers. Universal coupler is a mechanical connection which transmits rotary motion between various segments of the torque tubes. Universal coupler mitigates the forces in the torque tubes by allowing movements in two transverse directions i.e. vertical plane and in the horizontal plane. Due to this reason, less forces and moments are transferred at the base of the vertical posts which results in the stable structure over the floating platform.

Fig 1a. illustrates the floating PV photo voltaic solar tracker 100. The floating solar tracker includes PV modules 120, a Module Mounting Structure (MMS) 140, and a floating structure (FS) 160. The floating solar tracker can be scaled to include a larger number of PV modules 120. The PV modules 120 are installed on torque tube through hat rails which are mounted on top of the module mounting structure 140 which are set on top of the floating structure 160. PV modules 120 are mounted on hat rails 141. The hat rails can be mounted on the torque tube 142. The hat rails 141 consist of a steel hollow section welded to the angle sections to form a assembly. The assembly is mounted on the torque tube and a bolted connection holds the assembly with the torque tube. The height of the hat rail is designed in such a manner that it increases the solar radiation at the rear side of the PV module.

The torque tube is mounted on a vertical post 143 at regular intervals throughout the length of the PV module row. The torque tube 142 passes through journal assembly 144 which allows rotation about the torque tube axis. Self-lubricating collared polymer bearings 145 give long-term maintenance free operation and high reliability. Polymer Bearing allows the rotation of modules with torque tube so that their angle is maximized in relation to the sun. The torque tube of the MMS could be circular, hexagonal, octagonal or any other custom shape. The motor rotates the torque tube from -θ to +θ⁰, tracking the sun in the East-West direction. In the longitudinal direction at the level of the torque tubes 142 a pair of modified connections similar to a universal joint 146 is provided between the vertical posts 143. The function of this special connection 146 is to prevent the transfer of additional moments generated due to the environmental loads. This is achieved by allowing the torque tube between the special connections to move in the vertical and the horizontal plane.

Drag and lift produced by the wind on the surface area of solar modules causes a torsional moment on the torque tube and tracker structure and may induce torsional instability in the torque tube and structure due to the flutter or galloping. Hydraulic dampers are used to reduce the intensity of galloping and reduce the potential risk of damage to the torque tube, tracker structure and the PV modules. The height of the posts and the pitch distance are optimized to maximize the generation gain obtained from the system.

As shown in Fig 1b. slew drive 147 is a gearbox designed to handle radial or axial loads and allows the transmission of torque. A robust electro-mechanical actuator 148 with safety interlocks for travel limits is operated by closed loop feedback to control system for higher accuracy. In addition, the slewing ring bearing, at the heart of the drive, enables it to withstand high moment loads. A Permanent Magnet DC motor is used to provide power for rotation of Slew drive.

MMS 140 is secured to the floating structure 160 via vertical posts which are spaced at regular intervals. An inter-connection system 151 connects the vertical post to the floating structure 160. The interconnection system is designed such that the bearing stresses at the interface of the MMS 140 and the floating structure 160 are within the allowable values. The interconnection system consists of the metal sections which secures the MMS to the floating structure. The connection of the float with the metal structure is done at the ears of the floats 152. An HDPE pin 153 of a certain length serves a dual purpose of achieving float-float connection, and a float-metal connection. The float and the ear thickness is sufficient to prevent stress concentrations, proper load distribution, and within the acceptable manufacturing constraints.

The interconnected plastic rafts used for mounting these PV modules are called Floaters 161. Floating structure 160 consists of a pontoon like Floaters 161. Pontoons can be PVC or HDPE blocks satisfying the buoyancy, strength, stability, and durability parameters. The floating structure has a mechanism to prevent water filling inside the floating body. The blocks can be square, rectangular, or hexagonal extrusions or any other custom shape. Floating structure can include hollow pipes which provide adequate buoyancy and stability for the floating tracker. Floating solar islands are affected by environmental loads, wind, waves, and current. Fig 2. Shows the anchoring and the mooring of the floating PV photo voltaic solar tracker 200. The function of the anchoring 220 and mooring system 240 is to prevent the islands from drifting or changing their orientation under these loads. The floating arrangement is such that it is adequately supported in both N-S and E-W directions which helps in the uniform distribution of loads for the anchoring and mooring of the system. The mooring system is connected to the floating structure at one end and the anchors at the other end.

Fig 3. Describes the scalability/ plurality of the floating tracker system 300. The tracker can combine many PV modules in the torque tube direction (N-S) which can be rotated by a single slew drive motor located at the center post 310. A truss type skeletal arrangement 320 in the longitudinal and the transverse direction can support the spectral or diffused reflector for the generation gain. The structural arrangement can also include flexible ropes on which the reflectors can be mounted. Thus, the combined contribution (300) of the solar tracker, floating bodies, and reflectors is made scalable as per the project requirement.

Fig 4. Illustrates the vertical post and float pattern arrangement 400. The vertical post is mounted on a n×n floats having a certain pattern so as to ensure balance against overturning forces and also serve as supporting elements for walkways 660. The pattern consists of a stable arrangement and can include other stable forms such as cross form or Y- form or any other custom shape. Each vertical post relates to a float pattern, and the assembly of vertical post and float patterns are connected through structural sections which can be plane, angle, channel, I-section, or any other custom shape. This enables plurality of the floating tracker system in both directions. The vertical post is connected to the structural sections through the bolting with base plates 450. This may also include welding of the structural sections with/without the use of base plates.

Fig 5. shows the metal grateway arrangement in the E-W and the N-S directions 500. In the E-W direction a modular metal/composite grateway 510 can provide multi-purpose utility of walkway 660 for operation and maintenance, and also for supporting the electrical wiring, cable system 520 etc. In the N-S direction a plurality of grateways 510 are provided which are adequately supported by the floats at regular intervals 540. This arrangement of grateways 510 duly supported by floats which are regularly spaced provides buoyancy as well as reduces the maximum deflection in the grateways 510.

ii). REFLECTOR SYSTEM:

Fig 6a. describes the optical reflector arrangement 600 which can be installed at the top of the floating structure at a height lower than the elevation height of solar PV modules. Plurality of reflectors 620 cover footprint area of PV modules and extends to the next tracker row completely or partially. The optical reflector 620 consists of a thin layer and is diffused in nature. The perforated reflector sheets 640 are mounted on top of the floats and are supported either through plurality of wire ropes 650 or through rigid substrates supported at regular interval in NS and EW directions as shown in Fig 6b. The reflectors are connected to the plurality of base support structure through appropriately grafted slots for accommodating the wavy motion of the water body. The reflector system is inclined at ±θ towards the East and West direction so that there is no accumulation / stagnation of water. The walkways 660 between two tracker rows in EW direction, maintains and regulates separation between two tracker rows. The complete assembly of reflector with support is detachable for maintenance of the tracker.

iii). SMART COOLING SYSTEM

Fig 7. Describes the arrangement of the cooling system 700. Plurality of HDPE pipes 720 with suitable diameter are laid down along the length tracker in N-S direction, as well as along the pitch direction (E-W direction). The pipe design used for cooling is flexible to accommodate the wave motion and cools down the front surface of the module and it is connected with floats with necessary clamping. This network allows the availability of required quantity of water with every unit module of tracker. Plurality of HDPE flexible Inlet water pipes 720 with foot valve and strainer reaching sufficient depth of reservoir to fetch cool and potable water, will draw the water of required quality. Filters / strainers may remove large debris, sediments, or solid particles that may come up through the suction line and clog or jam the foot valve, supply pipe, pipe network, and damage the pump. An HDPE pipe tee fitting is used to distribute inlet water in two directions. For connecting distribution pipes with different diameters, compression Tee is used. At the outlet, plurality of suitable nozzle / sprinklers 740 uniformly cater to the nearest and farthest solar PV modules of the solar tracker structure. The nozzle / sprinkler 740 are adjustable i.e. up 760 or down 740 , wet or dry, for maximum convenience. Dedicated nozzle / sprinkler 740 cools down a pre-defined number of PV modules. Placement and selection of nozzles are done in such a way that water does not reach the rear side of the module where electrical circuits are housed. The sprinklers 740 are mounted at a specified distance from the edge of nearest PV module to prevent shading on it. The smart cleaning system offers dual benefits i.e. increased generation because of the cooling effect, and less cleaning of the module which reduces the O&M cost.

Plurality of submersible type of pump-sets with required head and wattage capacity, unidirectional gate valves for flow control, a pressure release valve (PRV) to regulate pipeline pressure and release valves are used to ensure safety of the pipe network. Pressure gauges, flow meters are used to monitor and control the required pressure.. Pneumatically-actuated diaphragm valves is used for control purposes in pipeline network, although quarter-turn types such as ball and butterfly valves can also be used according to the requirement. Control valves is operated with solenoid valve (DC). The hydraulic actuators respond to changes of valve position through solenoid valve which runs on external DC power. Automatic control system requires an external power source, which is operated on timer control. The smart cooling system involves automatic control system comprising of control module, timer control, pressure reducing valves, flow control valves, back-pressure sustaining valves, altitude valves, and relief valves. A multi stranded steel wire is used to tie the pipes, pump, float, reflector, and other connections wherever necessary as per requirement.

iv). SMART TRACKER CONTROLLER

Proposed system consists of Programmable Logic Controller (PLC) section and Intelligent Motor Controller (IMC) section. PLC is major component of control System which is programmed in such a way that various operation modes of HSAT such as sun tracking mode, backtracking (shadow avoidance), wind stow mode, cloud optimization mode, maintenance mode, emergency mode etc. form its basic framework. PLC runs sun position algorithm, back tracking algorithm and control algorithm. It collects input from field devices such as Inclinometer, Encoder & Anemometer (Wind speed sensor) and IMC section and decides the operation mode & rotation required and give command to IMC section accordingly to operate motor. IMC section consist of Intelligent motor controller which receive command from PLC of controller module, check status of connected field devices (east & west limit switch, emergency switch) and provide power supply to motor for forward and reverse operation.

In one aspect the invention has a floating solar tracker for bifacial modules comprising of a plurality of PV modules PV 120, a PV Module Mounting Structure MMS 140, a Floating Structure FS 160, a plurality of Hat Rails HR 141, a plurality of Torque Tubes TT 142, a plurality of Vertical Post VP 143, a pair of Universal Joint VJ 146, a Journal Assembly JA 144, a Collared Bearing CB 145 and are so arranged structurally that they can operate operatively. The PV module PV 120 is mounted on Hat Rails HR 141. The Hat Rails HR 141 is mounted on Torque Tubes TT 142. The Journal assembly JA 144 is mounted on vertical post VP 143. The Torque Tubes TT 142 is housed within the Journal Assembly JA 144. The Vertical Post VP 143 is a linear post fixed on MMS 140. The Module Mounting Structure MMS 140 is mounted on Floating Structure 160.

The Universal Joint VJ 146 is connected longitudinally between Vertical Post VP 143 at the level of Torque Tubes TT 142 for facilitating the motion of Torque Tubes TT 142 in the vertical plane and in the horizontal plane.

The Torque Tubes TT 142 is positioned through Journal Assembly JA 144, thereby allowing the Torque Tubes TT 142 rotation about TT axis.

The Torque Tubes TT 142 is adapted with Collared Bearing CB 145 thereby allowing rotation of PV module PV 120 alongwith Torque Tubes TT 142, to face the sun orthogonally.

The arrangement is novel in the design that the Floating Structure FS 160 is specifically adapted to float on water bodies and also in the mutual mounting arrangements of positioning the PV module PV 120, Hat Rails HR 141, Torque Tubes TT 142, Vertical Post VP 143, Module Mounting Structure MMS 140, Floating Structure FS 160 and in the Universal Joint VJ 146 mitigating resultant forces on the Torque Tubes TT 142 thereby minimizing twisting and bending of Torque Tubes TT 142, Journal Assembly JA 144 allowing rotating motion of Torque Tubes TT 142 along its own axis and Collared Bearing CB 145 allowing PV module PV 120 to rotate alongwith Torque Tubes TT 142 such as to face the sun orthogonally.

In another aspect of the invention the motor is adapted to rotate the Torque Tubes TT 142 from -Θ˚ which is the predetermined maximum tracking angle towards the East to +Θ˚ the predetermined maximum tracking angle towards the West for tracking the sun in the east west direction.

In another aspect of the invention the slewing drive powered by the motor is coupled to Torque Tubes TT 142 for rotating the Torque Tubes TT 142.

In another aspect of the invention the slewing drive is coupled to Torque Tubes TT 142 of one or more of solar tracker rows of PV module PV 120.

In another aspect of the invention the Hat Rails HR 141 is positioned such that PV module PV 120 is at a height above the Torque Tubes TT 142, thereby eliminating shading of Torque Tubes TT 142 on rear side of PV module PV 120 and to maximize bifacial gain.

In another aspect of the invention the Module Mounting Structure MMS 140 is arranged between two Vertical Post VP 143 in N-S direction and Floating Structure FS 160 is arranged in E-W direction between two consecutive rows of PV module PV 120.

In another aspect of the invention the Module Mounting Structure MMS 140 and Floating Structure FS 160 is one or more.

In another aspect of the invention the hydraulic dampers are connected to Hat Rails HR 141 to Vertical Post VP 143 in order to dampen the intensity of galloping and fluttering of Module Mounting Structure MMS 140.

In another aspect of the invention the Floating Structure FS 160 is a single float or a combination of plurality of connected floats having a predetermined buoyancy.

In another aspect of the invention a walkway WW 660 is arranged between consecutive rows of PV module PV 120 along the E-W direction and between consecutive Vertical Post VP 143 along N-S direction, either single or vertically stacked, either of polymer or of a metal grate walkway.

In another aspect of the invention the walkway arranged between consecutive rows and vertical posts is designed to serve multipurpose utilities and as spreader bar which is connected to mooring and anchoring system.

In another aspect of the invention the reflector sheets RS 640 are arranged at a height lower than solar PV module PV 120.

In another aspect of the invention the reflector sheets are reflective material glued or painted onto a substrate, which is flexible or rigid.

In another aspect of the invention the reflective material exhibits higher albedo than water, thereby configured to increase sun-light intensity on rear and front side of PV module PV 120.

In another aspect of the invention it has cooling arrangement with sprinklers SP 740 mounted on Vertical Post VP 143.

Through present invention the inventors have to overcome all the stated limitations of existing design of floating PV system through the unique and novel modular and scalable horizontal single axis tracker structure design favoring bifacial solar PV module technology, novel wave mitigating interconnection system, sun-reflecting system, smart PV module cooling system and bifacial compatibility makes it ideal for deploying utility scale solar PV plants on floating water bodies.

The description and embodiments have been provided merely for the purpose of understanding and these shall not limit the scope of the invention. All variations and modifications that can be thought of by the skilled person is well within the scope of this invention.
, Claims:WE CLAIM :

1. A floating solar tracker for bifacial modules comprising of :-

a. a plurality of PV modules PV 120,
b. a PV Module Mounting Structure MMS 140,
c. a Floating Structure FS 160,
d. a plurality of Hat Rails HR 141,
e. a plurality of Torque Tubes TT 142,
f. a plurality of Vertical Post VP 143,
g. a pair of Universal Joint VJ 146,
h. a Journal Assembly JA 144,
i. a Collared Bearing CB 145,

wherein the

- PV module PV 120 is mounted on Hat Rails HR 141,
- Hat Rails HR 141 is mounted on Torque Tubes TT 142,
- Journal assembly JA 144 is mounted on vertical post VP 143,
- Torque Tubes TT 142 is housed within the Journal Assembly JA 144,
- Vertical Post VP 143 is a linear post fixed on MMS 140,
- Module Mounting Structure MMS 140 is mounted on Floating Structure 160,
- Universal Joint VJ 146 is connected longitudinally between Vertical Post VP 143 at the level of Torque Tubes TT 142 for facilitating the motion of Torque Tubes TT 142 in the vertical plane and in the horizontal plane,
- Torque Tubes TT 142 is positioned through Journal Assembly JA 144, thereby allowing the Torque Tubes TT 142 rotation about TT axis, and
- Torque Tubes TT 142 is adapted with Collared Bearing CB 145 thereby allowing rotation of PV module PV 120 alongwith Torque Tubes TT 142, to face the sun orthogonally.
- the arrangement characterized in the Floating Structure FS 160 is specifically adapted to float on water bodies and also in the mutual mounting arrangements of positioning the PV module PV 120, Hat Rails HR 141, Torque Tubes TT 142, Vertical Post VP 143, Module Mounting Structure MMS 140, Floating Structure FS 160 and in the Universal Joint VJ 146 mitigating resultant forces on the Torque Tubes TT 142 thereby minimizing twisting and bending of Torque Tubes TT 142, Journal Assembly JA 144 allowing rotating motion of Torque Tubes TT 142 along its own axis and Collared Bearing CB 145 allowing PV module PV 120 to rotate alongwith Torque Tubes TT 142 such as to face the sun orthogonally.

2. The floating solar tracker wherein a motor is adapted to rotate the Torque Tubes TT 142 from -Θ˚ which is the predetermined maximum tracking angle towards the East to +Θ˚ the predetermined maximum tracking angle towards the West for tracking the sun in the east west direction.

3. The floating solar tracker as claimed in claim 1 and 2, wherein slewing drive powered by the motor is coupled to Torque Tubes TT 142 for rotating the Torque Tubes TT 142.

4. The floating solar tracker as claimed in claims 1 to 3, wherein the slewing drive is coupled to Torque Tubes TT 142 of one or more of solar tracker rows of PV module PV 120.

5. The floating solar tracker as claimed in claim 1, wherein Hat Rails HR 141 is positioned such that PV module PV 120 is at a height above the Torque Tubes TT 142, thereby eliminating shading of Torque Tubes TT 142 on rear side of PV module PV 120 and to maximize bifacial gain.

6. The floating solar tracker as claimed in claim 1, wherein Module Mounting Structure MMS 140 is arranged between two Vertical Post VP 143 in N-S direction and Floating Structure FS 160 is arranged in E-W direction between two consecutive rows of PV module PV 120.

7. The floating solar tracker as claimed in claim 6, wherein Module Mounting Structure MMS 140 and Floating Structure FS 160 is one or more.

8. The floating solar tracker as claimed in claim 1, 3 and 4 wherein hydraulic dampers are connected to Hat Rails HR 141 to Vertical Post VP 143 in order to dampen the intensity of galloping and fluttering of Module Mounting Structure MMS 140.

9. The floating solar tracker as claimed in claim 1 wherein the Floating Structure FS 160 is a single float or a combination of plurality of connected floats having a predetermined buoyancy.

10. The floating solar tracker as claimed in claim 1, wherein a walkway WW 660 is arranged between consecutive rows of PV module PV 120 along the E-W direction and between consecutive Vertical Post VP 143 along N-S direction, either single or vertically stacked, either of polymer or of a metal grate walkway.

11. The floating solar tracker as claimed in claim 9, wherein the walkway arranged between consecutive rows and vertical posts is designed to serve multipurpose utilities and as spreader bar which is connected to mooring and anchoring system.

12. The floating solar tracker as claimed in claim 1, wherein reflector sheets RS 640 are arranged at a height lower than solar PV module PV 120.

13. The floating solar tracker as claimed in claim 12, wherein said reflector sheets are reflective material glued or painted onto a substrate, which is flexible or rigid.

14. The floating solar tracker as claimed in claims 12 and 13, wherein the reflective material exhibits higher albedo than water, thereby configured to increase sun-light intensity on rear and front side of PV module PV 120.

15. The floating solar tracker as claimed in claim 1, wherein it further has cooling arrangement with sprinklers SP 740 mounted on Vertical Post VP 143.