WO2017187259A1

WO2017187259A1 - Sun position tracker for concentrated photo voltaic power generation system and the method for tracking thereof

Info

Publication number: WO2017187259A1
Application number: PCT/IB2017/000492
Authority: WO
Inventors: Shankar Rao Chandrasekhar NAGASANDRA
Original assignee: AGARWAL, Reema
Priority date: 2016-04-26
Filing date: 2017-04-28
Publication date: 2017-11-02
Also published as: WO2017187445A1; WO2017187256A2; WO2017187258A1; WO2017187443A1; WO2017187258A4; WO2017187256A3

Abstract

A sun position tracker for supporting concentrated photo voltaic (CPV ) power generation system, said sun position trackercon figured for moving said CPV for tracking the path of the sun, said solar tracker comprising: a CPV power generation an system supported on the open cage like structure disposed on gimbal (V frame) with a base configured for rotatably supporting the gimbal at a given orientation from the ground, the ground support and two V shaped frames are located on separate platforms and further supported over four pillar structure which are grouted to the earth thereby providing three dimensional stability including means for raising, lowering and changing orientation of the gimbal; wherein the platforms supporting the V shaped frames are driven by linear rack and pinion arrangement and the said platform; are hinged to respective base structure with bearings providing dual axis and vertical tilt with five degrees of freedom.

Description

FIELD OF INVENTION

The present invention generally relates to a tilt-tilt dual axis sun position tracker for concentrated photo voltaic power generation system. More particularly, the present invention discloses sun position tracker employing longitudinal tilt (N_S) and Lateral tilt (E_ W) , incrernentallyand controlled by feedback from sun sensor. The proposed system employs 4 quadrant sun sensors ( LDRs / PV cells) with proper geometry of the sensor blocks supports 2 π tracking over the day and year in closed loop and controlled by limit switches .

BACKGROUND OF THE INVENTION

Solar energy is in use world-wide. Both heat energy harvesting and direct conversion of solar to electrical power are known in the art. Nowadays, the significant su rge in demand for alternative sources of energies (i.e. , wind , solar, hydro, etc.) has created opportunities for fast development of the global alternative energy infrastructure, measurable at the giga-watts levels. The construction of new solar power plants has been intensified, leading to a subsequent boost in manufacturing and generating capacities worldwide and, thus, to significant reductions in costs with the shift towards an economy of scale and minimise the land usage. Measurable drops in the PV solar panel manufacturing and installation costs resulted in comparable reductions of the overall power plant costs. However, increase in performance of the PV solar panel modules and improvements of the solar power system effectiveness through technical innovations have a more direct and stronger impact on reducing costs by allowing for a lower number of PV solar panels for a desired power output, thus a smaller footprint of the respective PV solar installation. To this end, new technological advances in the rapidly growing field of concentrated PV cells underline a genuine option for significant reductions in PV cell surface area per kW of electrical output and, therefore, a real possibility to produce electricity at competitively lower costs.

The solar light concentration for efficient solar energy harvesting is also a well-known phenomenon. Among solar electricity generation technologies, photovoltaic (PV) technologies have seen the largest growth over the last few years and PV is increasingly seen as a viable alternative for electricity generation. However; the efficiency of this technology has well known limitations: for direct solar irradiation on Si/CIGS PV panels, the efficiency of solar to electric energy conversion peaks at around 15%. Recently, commercially available multi-junction with efficiencies exceeding 40% has been developed. However, the price increase associated with manufacturing these cells is much higher than the efficiency increase, making these high-efficiency cells unsuitable for normal PV panels. Concentrated photovoltaic (CPV) systems provide the solution by using an optical concentrator to concentrate the sunlight using before it reaches the cell. The result is more sun Light energy hitting the PV surface thus requiring a much smaller cell for the same electrical output. The benefit of so doing is twofold : 1 ) the economy of the system is improved by replacing expensive PV cells with less expensive optical elements ; 2) the efficiency of the PV cell is augmented by higher incident solar fluxes resulting from the concentration. Using the same amount of land, CPV systems can produce more electricity, more efficiently and using much less PV material than conventional PV systems. Recent studies have shown that the. majority of cost for a CPV system is represented by the concentrator, its structure, and the tracking system mechanism . Therefore the greatest cost reductions can be achieved by targeting these technologies.

Regarding the CPV orientation, it is known that a perpendicular orientation of the panels to the incident angle of sunlight maximizes the solar irradiation of the panels, thus maximizing the total amount of solar energy converted to electrical energy. The normal to the cell is perpendicular to the cell's exposed face. The sunlight comes in and strikes the panel at an angle. The angle of the sunlight to the normal is the angle of incidence (Θ) as shown in Fig 2(a). Assuming the sunlight is staying at a constant intensity (λ) the available sunlight to the solar cell for power generation (W) can be calculated as:

W = A λ C0 (9)

Here, "A" represents some limiting conversion factor in the design of the panel because they cannot convert 1 00% of the sunlight absorbed into electrical energy. By this calculation, the maximum power generated will be when the sunlight is hitting the PV cell along its normal and no power will be generated when the sunlight is perpendicular to the normal. With a fixed solar panel, there is significant power lost during the day because the panel is not kept perpendicular to the sun's rays. A tracking system can keep the angle of incidence within a certain margin and would be able to maximize the power generated.

Due to the fact that the earth rotates on its axis and orbits around the sun, if a PV cell/panel is immobile, the absorption efficiency will be significantly less at certain times of the day and year. The use of a tracking system to keep the PV cell/panel perpendicular to the sun can boost the collected energy by 1 0 - 1 00% depending on the circumstances. If a tracking system is not used, the solar panel should still be oriented in the optimum position. The panel needs to be placed where no shadow will fall on it at any time of the day. Additionally, the best tilt angle should be determined based on the geographical location of the panel . As a general guideline for the northern hemisphere, the PV panel should be placed at a tilt angle equal to the latitude of the site and facing south. The incident angle of sunlight varies in the east-west direction as a function of the time of day and the north-south direction as a function of the time of year. Accordingly, sun-tracking devices that attempt !o keep the photovoltaic panel position perpendicular to the direction of the sunlight at different times of day and year are often mechanically complex, expensive to manufacture, and prone to malfunctioning.

As is known, solar trackers are used to improve photovoltaic panel production by capturing maximum solar energy radiation during the longest possible time through systems following the path of the sun. any companies market solar trackers and there are many models with both single and dual-axis tracking.

As per oneprior art the solar panels are fixed with anchors on the two shafts, preventing their expansion. In another prior art solar energy collectors are proposed to mount for rotation about a vertical axis to adjust the azimuth and for tilting to adjust the altitude so as to point the collector toward the sun, especially during midday hours, but practical and economical drive and control mechanism for effecting the rotation of a base turntable and tilting of the collector relative to the base has not been available. Sophisticated tracking mechanism for tracking the sun by automatically rotating a .turntable about a vertical axis for azimuth adjustment and tilting a target about a horizontal axis for elevation adjustment are very complex and expensive.

Another problem arises during installationof a CPV resu lt from their stability given that since they are planar surfaces, the anchor and rotation points are located outside the plane passing through their centre of gravity, causing asymmetrical static loads limiting their weight and dimensions so as to not overload the rotation points. This situation is worsened by the stresses resulting from the wind which generate thrusts and overturning moments making them rather unstable.

A variety of techniques for adjusting the position of the photovoltaic panels exist in the field. Some systems for changing the^' angle of the photovoltaic panels have the panels arranged in a 2-D matrix of columns and rows. These systems can adjust the panel angle about two axes. The photovoltaic panels are pivoted by a mechanism that has multiple drive bars and pivoti ng points. Furthermore, all the panels in a given column are mounted above a tilt axis which rotates both the panels and the associated pivoting mechanisms, thus adding complexity to an already intricate panel pivoting mechanism. Using one axis of tracking can provide a significant power gain to the system. It is claimed that one axis trackers are placed into the following classifications: horizontal single axis tracker (HSAT) , vertical single axis tracker (VSAT), tilted single axis tracker (TSAT), and polar aligned single axis tracker (PASAT) as shown in Fig 2(b).

Some other systems for changing the angle of the photovoltaic panels have a solar tracking system that changes the solar panel angle in the north-south direction only. The east-west axis may only be adjusted manually at the installation time. Thus, these systems lack the ability to automatically adjust the east-west orientation of the _ photovoltaic panels to follow the direction of the sunlight during the day. Therefore, a need remains for systems that can adjust the angle of the photovoltaic panels in two directions, while being capable of withstanding high mechanical loads and providing a wide range of rotation angles. In the prior art an US specification US429041 1 discloses solar energy collector sun- tracking apparatus and method wherein the solar energy collector is mounted for adjustable azimuth rotation about a vertical axis and adjustable elevation tilting about a horizontal axis for pointing toward the sun. The collector is driven for rotation about the vertical axis and for tilting about the horizontal axis by drive mechanism controlled by the angle of incidence of the sun's rays to the collector when the insolation is above a predetermined intensity. When the insolation is below such predetermined value, the drive mechanism is controlled by a stored computerized program. Control responsive to the sun's rays is affected by at least one light sensitive photoelectric cell. Preferably one pair of cells is arranged in a horizontal axis and another pair is arranged in a plane perpendicular to such horizontal

In another prior art a PCT specification WO2012T1 61 02A2 discloses solar trackers drive configured to adjust a tilt position of a solar collector assembly so as to tract the sun. The drive can include hardware for providing feedback control of the orientation of the solar collector assembly. A method for calibrating the drive can include moving the drive to a reference position and saving an output value from a sensor configured to detect the orientation of the drive. The reference value output from the sensor can then be used in determining the target output value from the sensor required to achieve a desired orientation.

In another prior art an US specification US7763835B2 discloses dual-axis solar tracker mounted on a two-slope grate column wherein the photovoltaic panels are arranged in spaced rows at different levels and two slopes, favoring their ventilation and the expansion of the frame; the panels being fixed by means of yokes and clips to a support (3) anchored to the H-shaped frame (4) resting on swivelling supports of a tower having little height supporting the entire structure, its tilt being variable by means of a tension device, the side longitudinal beams (4 a) being extendible to house more rows of panels (1 ) since the remaining structural components, tower, bearings, column and base have been oversized for that purpose.

The advances in this field involve the design of larger, stronger and more reliable trackers designed for a useful life of up to 25 years, which are less sensitive to the wind and provide the panels, with better conditions of durability and performance, in turn reducing the specific costs.

SUMMARY OF THE INVENTION

The present invention primarily relates to a systems arrangements and methods for maximizing the harvested solar energy using multistage parabolic shaped concentrated Photo-Voltaic (CPV) generation. The proposed systematic approach is feedback controlled, automated, remotemonitored and supervisory controlled, with dawn to dusk and over the complete year tracking system with a provision of peaki ng the efficiency in terms of concentration collection, generation and power transportation, which can yield an efficient, low cost system applicable for miscellaneous applications and can be scaled efficiently to a desired size as shown in Fig 1 . As per an embodiment of the present invention, there is provided sun tracker arrangement. In contrast to the current technology being adopted with positioning of the concentrator by controlling elevation over azimuth plane bei ng adopted in satellite communications, which limits the operational range for dawn to dusk operation and further the twisting of cables and pipes cause an added problem . The current invention uses 2π4 quadrant sun sensing system in tilt-tilt and incremental positioning mode like a dancing doll over the complete operation without any limitation in dawn to dusk operation. This tilt-tilt mode operates in X-X and Y-Y axes alternatively based on feedback from the sun positioning sensor. This tilt-tilt tracker adopts rack and pinion linear motion into a rotatory motion with a dual axis tilti ng mechanism of X-X over Y-Y and is supported by simply supported dual beam frame structures.

As per another embodiment of the present invention, there is a linear to rotatory motion converter of X-X and Y-Y movement of parabolic dish (primary) . The said motion converter is based on well-known rack and pinion arrangement.

As per another embodiment of the present invention, there is provided dual beam frame structures for erection of the multistage CPV as disclosed herein. Therefore such as herein described there is provided a sun position tracker for supporting concentrated photo voltaic (CPV) power generation system , said sun position tracker configured for moving said CPV for tracking the path of the sun , said solar tracker cornprising:a CPV power generation system supported on the open cage like structure disposed on gimbal (V frame) with a base configured for rotatably supporting the gimbal at a given orientation from the ground, the ground support and two V shaped framesarelocated on separate platforms and are further supported over four pillar structure which are grouted to the earth thereby providing three dimensional stability including means for raising , lowering and changing orientation of the gimbal ;wherein the said platforms support the V shaped frames are driven by linear rack and pinion arrangement and the said platforms are hinged to the respective base structure with bearings providing dual axis and vertical tilt with five degrees of freedom . Thus the present invention teaches a novel combination and arrangement of parts, either commercially available or specifically designed and described below. It should be understood that changes and variations may be made in the detailed design of the parts, including the solar concentration means, the HC sunlight transmission and light distribution devices and the compact 3D CPV assembly, thermal management, power transmission and storage without departing from the spirit and scope of the invention as claimed.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig 1 (a) _.and (b) illustrates a pictorial representation of a parabolic dish with solar panel mounted on dual axis tilt/tilt tracker in accordance with the present invention ; Fig 2 (a) illustrates the angle of incidence of sunlight to a solar cell ;

Fig 2 (b) illustrates different one axis trackers as prior art;

Fig 3 illustrates a line drawing for the Sun tracker arrangement in 2ττ 4 quadrant system configured for tracking sun position using the feedback from sun sensor in accordance with the present invention;

Fig 4 illustrates the line drawing of the dual beam frame structure configured for robust erection and smooth movement of the multistage CPV in accordance with the present invention ; DETAILED DESCRIPTION

The embodiments of tilt-tilt dual axis sun position tracker for concentrated photo voltaic power generation system employing longitudinal tilt (N_S) and Lateral tilt (E W), incrementally is shown in Fig 1 . The proposed system employs 4 quadrant sun sensors ( LDRs / PV cells) with proper geometry of the sensor blocks supports 2 π tracking over the day and year in closed loop and controlled by limit switches. The purpose of a solar tracker as herein disclosed is to accurately track the position of the sun. This enables solar panels interfaced to the tracker to obtain the maximum solar radiation. With this particular solar tracker a closed-loop system was made consisting of an electrical system and a mechanical system. The overall block- diagram can be seen in Figure-3.The sun position tracker comprises of two V shaped frames which are located on to a simply supported four pillar structure which are grouted to the earth with proper foundation. FIG. 1 (a) and (b) shows a pictorial representation of the proposed tracker system with CPV- system for concentrating and transforming solar energy into electrical energy. The proposed system includes a primary parabolic concentrator configured for reflecting all impinging solar insolence to its focal point which is collected and further concentrated by a secondary collector concentrator and thereafter exposed to a receiver solar panel configured for efficient conversion of concentrated solar insolence to equivalent electrical power. The said tracker system further includes a sun sensing mechanism configured for sensing and tracking the real time location and intensity of the available sun light. The sun sensing and tracking mechanism as disclosed herein is based on 2π 4 quadrant topology. The sun position sensor is mounted on disclosed multistage concentrated photo voltaic system for real time sensing and tracking of sun round the clock over the year continuously.

SUN TRACKER :-

As discussed, the primary issue for maximum harvest, which is to be taken into account in CPV is that angle of illumination or insolence is necessarily normal/ orthogonal to solar PV panel. The angle of insolence is very critical with higher concentration ratios. This calls for an accurate sun tracking systems on which the concentrator optics and solar PV receivers are mounted. A typical sun tracking system is shown in Fig 3. Conventional sun dual axis tracking systems incorporate methodology of Tilt - tilt rotation for elevation tracking and rotation for azimuth tracking similar to satellite tracking solution of communication system.

The normally these systems use the sun position based on the ephemeris of the sun and earth positions as calculated from astronomy. Then technology suits well for geostationary satellites and rotating earth. The rotation of tracker in azimuth complicates the cabling and piping designs or tracker automation systems by sensing the limit switches ensuring the no jumbling of pipes and cables. This being an open loop control system the tracking accuracy depends on the information of longitude and latitude of the installation and time of the day..

In contrast, the disclosed sun tracking system is a longitudinal tilt (N _S) and Lateral tilt (E._W), incrementally. Hence high speed tracking on longitudinal/lateral directions are avoided. The proposed system employs 4 quadrant sun sensors (LDRs / PV cells) with proper geometry of the sensor blocks supports 2 π tracking over the day and year in closed loop which is known to a person skilled in the art and is further controlled by limit switches. This tracker allows the independence f rom installation requirement of aligning the axes in North __South direction over year and East West Direction over the day.

There is no necessity of feeding sun position or location data for tracker controlling purpose. (Accurate longitude and latitude data during initial set up of the tracker.) The position of the tracker is processed to be independent of sun light intensity. By setting threshold for intensity, the start and stop function of the sun tracker can be controlled.

The movement of tracker could be very slow over the day and over the year. Incremental movement of tracking is being implemented.

The tracker functions dual axis tilt-tilt mode of traverse. Also the tracker movement is essentially an incremental rotational movement. The platform and dish will be a driven by linear rack and pinion connected to platforms and the platforms are hinged to the respective base structure with bearings. The dish is mounted on a 5dof (5 degrees of freedom) gimbals (V frames).

Mechanical design of tracker and dynamic envelope estimation

The Tracking principle of dual axis tilt platform mounted on 4 pillar structure with 4 degrees of freedom. (North, South, East and West and vertical tilt forming 5 degrees of freedom). The design of structure takes in to account of self-loading and wind load as per international standards of self-load in worst case condition and wind loads. The tracker will stop tracking for wind loads > 70 km/hr. The design also includes a closed loop automation algorithms and control logics which include motor control and interlock logics. The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather a purpose of the embodiments chosen and described is so that the appreciation and understanding by any person skilled in the art of the principles and practices of the present invention can be facilitated.

The design of the sun tracker as shown in Fig 4 includes the different safety interlocks available and is taken into account. The extreme limits, wind loads and intensity of illumination for safe operation of the tracker. The pulse currents form the tracker and checked for proper functioning of the rack and pinion movement and rotation of the platform in both axes. The sun tracking system employs a PLC based control application which tracks the sun in 2π 4 quadrant motion (dual axis) , with incremental motion on each direction, by the use of linear to rotary motion converter. The sensor used for tracking the sun position is 4 quadrants LDR based sun sensors. The additional feature is PLC based self-cleaning facility.

Control Algorithms and logics

a) Power ON self - test of the tracker logic;

b) Wind speed check to be below specified limits ;

C) The tracker position to be within limits;

d) Sun intensity above/below limits;

e) First X-X movement is performed over the specified duration ;

f) After the X-X movement is stopped, Y-Ydirectiori movement is accomplished g) Step e and f will be repeated till the position error reaches to zero and below the threshold being detected.

The 2π sun Sensor and sensor electronics SUN position sensing and processing algorithms and scheme:-

• The sensor which are proposed to be used are LDRs (Light dependent resistors)

• The construction sensor should block sun light illuminating the LDR East should not illuminate the LDFM/Vest. Until Sun illumination is equal on both LDRs.

• The same logic holds good for North _. South LDRs.

• To overcome the noise and glitches The LDR are normally positive biased.

• The SUN position is^" detected by acquiring the signal voltages (V_East and V West). By calculating ratio of (V East - Vwest) / ( V east + West) .

• The vectored result of the calculation defines the position Sun with respect to the tracker and concentrator

• V_east+V_West will show the Sun's Illumination conditions.

• The tracking function of the tracker can be controlled by comparing V__East+V _West with respect to a reference voltage to determine the Presence or Absence of Sun.

• In the case of CPV, keeping the voltage same as in conventional PV (by maintaining the solar PV temperature) the current levels shoot up as much as the concentration ratio.

• The primary concentrator concentrates the sunlight orthogonal to a tracked moving plane in 2π 4 quadrant positioning system with feedback control.

LINEAR TO ROTATORY MOTION CONVERTER:

The sun tracker as disclosed herein is configured for X X and Y-Y movement of parabolic dish (primary) . The tracker functions dual axis tilt-tilt mode of traverse. Also the tracker movement is essentially an incremental rotational movement. The platform and dish will be a driven by linear rack and pinion connected to platforms and the platforms are hinged to the respective base structure with bearings as shown if Fig 5. DUAL BEAM FRAME STRUCTURES:-

The currently used as prior art pole structure with a rotating pillar for azimuth rotation with tilt of dish accomplished by bearing structure. The limitation of positioning is limited to the tilt of the concentrator in elevation position and also limited by the rotation envelope of the azimuth however the existing systems do associate yrerotary motion of the cables and pipes twist / untwist leading to thermo-rnechanical fatigue / failures. The present invention discloses the use of four pole structure as shown in Fig 3, wherein each poles is grouted at four corners of a square / rectangle and a centre pole at diagonally middle portion for central and peripheral support of the multistage CPV. During the erection, the extreme limits, wind loads and intensity of illumination for safe operation of the tracker. During assembly, the pulse currents form the tracker and checked for proper functioning of the rack and pinion movement and rotation of the platform in both axes.

Dual axis feedback sun position sensor

The 3D sun sensor is a sun position and sun intensity detection device, which comprises of four LDR area detectors positioned in each quadrant of the 2π plane with a blocking vertical plane to maximise the contrast during large deviation of sun positions between X X and Y_Y planes. The presence or absence of the sun position (digital) can be obtained by comparing with the threshold control loop to put the control system in operation. As the control algorithm is essentially a null seeking system and the variations of intensities between the complementary pairs will be independent of sun intensity variation over the day and over the years. A complete loss of intensity will enable the control loop to be in sleep mode or operational mode in respect of the presence / absence of sun. The presence of sun will activate the operation when any of the detector is above the threshold level. Below the threshold, the system will enter into sleep mode.

The salient features and the design features of the sun sensor is dependent upon the required concentration of the sun. The equation for the distance and the height of the barrier between the detectors is a function of the concentration ratio which is essentially of:

X = distance of x axes LDR from centre

X = distance of y axes LDR from centre

Z - height of barrier.

The ratio of Z/X=tan θι__χχ Similarly Z/Y=tan 9_{C yy} where x and y are the position of sensors in X-Y plane and Z is the height of barrier.

The output of the comparing circuit of the sun sensor powers a driver circuit, which i n turn powers a motor and changes direction according to which sensor receives a higher amount of illumination. This orients the solar panel to be perpendicular to the sun. The sensor outputs are conditioned, digitized and computed for position sensing accuracy. However the proposed computation ensures the positional accuracy as position information is relative measure of the sun^'s intensity.

Where V-n corresponds to voltage developed across North sensor, V s corresponds to voltage developed across south sensor. V _ n-V s gives the sun position information, V n+V s gives the sun's intensity. The ratio of position error and intensity variation is independent of intensity. Similarly east and west sun^'s position error is computed.

The error signals are verified and serve as input to the control generation logic. The other information as dark condition, limit detection, hysteresis of error are all taken into account during the processing and computation.

The error signals of North _South and EasM/Vest are scanned at regular intervals and the motors of north/south/east and west are triggered alternately at predefined time intervals ensuring the correction of error is fast enough to position the solar panel orthogonal to the sun illumination or insolence. The positioning of the V frames/ dish with solar panel will be effected by two linear actuators ( rack and pinion actuators) . The sun position/ dish position will be resolved into cosine functions as

COS 9 in north south direction

And

COS φ in east west direction.

Hence the position of concentrator will be orthogonal to sun position over the day and over the year.

The salient features of the invention are:-

The structure of the tracker is simply supported by 4 pillars grouted to the ground, easy to design and implement the structure for high wind loads and maintain the centre of gravity with in the support base.

The two V frames constitute the Dual axis Gimbal structure also supported by bearings on to the main foundation structure, preventing from toppling during tracking and under high wind loads,

· Alternate scanning and error correction of the tracker in North/South and

East/West directions at sufficiently high speeds will ensure smooth seamless tracking.

The scanning mode also provides the advantage of high torque generated during start leading to minimising the power from the motors.

· The main feature of the TILT/TILT mode scan tracking solution is the cabling and piping associated with rotational tracking system coiling of the cables and pipes are avoided. Hence no slip ring requirement or stress and stretching of pipes and coils are overcome

The waviness during the motion can be controlled by suitably selecting the scan frequency and motor speed.

The TILT/TI LT scanned dual axis sun tracker ensures longer duration of tracking ( theoretically from dawn to dusk), also independent of positional accuracy during installation and commissioning( other trackers . need to be positioned to north/south direction) The tilt angle in North_ South/East . West direction is limited .

Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof , it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

!) 0 5

Claims

WHAT CLAIMED IS:

1 . A sun position tracker for supporting concentrated photo voltaic (CPV) power generation system, said sun position tracker configured for moving said CPV for tracking the path of the sun, said solar tracker comprising:

a CPV power generation system supported on the open cage like structure disposed on gimbal (V frame) with a base configured for rotatably supporting the gimbal at a given orientation from the ground, the ground support and two V shaped frames are located on separate platforms and further supported over four pillar structure which are grouted to the earth thereby providing three dimensional stability i ncluding means for raising, lowering and changing orientation of the gimbal ; wherein the platformssupporting the V shaped frames are driven by linear rack and pinion arrangement and the said platforms are hinged to respective base structure with bearings providing dual axis and vertical tilt with five degrees of freedom.

2. The sun position tracker as claimed in claim 1 , wherein the tracker movesin dual axis tilt-tilt mode of traverse and the said tracker movement is an i ncremental rotational movement.

3. The sun position tracker as claimed in claim 2, wherei n the tracker movement includes closed loop automation and control logics which include motor control and safety interlocks.

4. The sun position tracker as claimed in claim 3, wherein the said sun tracking system includes PLC based control logics which tracks the sun in 2ττ 4 quadrant motion (dual axis) , with incremental motion on each direction , by the use of linear to rotary motion converter.

5. The sun position tracker as claimed in claim 4, wherein the said PLC based control application is guided by control signals from a 3D 2ΤΓ sun sensor configured for sensing and processing incident solar insolence.

6. The sun position tracker as claimed in claim 1 , whereinthe said sun position tracker is configured to perform X-X axis movement over a specified duration and on completion , Y-Y axis movement is accomplished.

7. The sun position tracker as claimed in claim 5, wherein the sun sensor is configured to sense the presence or absence of the sun position (digital) by comparing with the threshold control loop to put the motor in operation and wherein the control loop is essentially a null seeking and independent of sun intensity variation.

8. The sun position tracker as claimed in claim 1 , wherein the sun sensor outputs are conditioned, digitized and computed for position sensing accuracy and error signals.

9. The sun position tracker as claimed in claim 1 , wherein the error signals of North _South and EasM/Vest are scanned at regular intervals and the motors of north/south/east and west are triggered alternately at predefined time intervals ensuring the correction of error and is fast enough to position the solar panel orthogonal to the sun illumination or insolence.

1 0. The sun position tracker as claimed in claim 1 , wherein the positioning of the V frames / CPV dish with solar panel is effected by two linear rack and pinion actuators.

1 1 . A method for tracking the sun position employing the sun position tracker as claimed in any of the preceding claims.