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Title:
SUN POSITION DETECTOR AND METHOD OF SENSING SUN POSITION
Document Type and Number:
WIPO Patent Application WO/2017/187445
Kind Code:
A1
Abstract:
A sun position detector assembly comprising: a square base member. a rigid post extending vertically from said base member; a single inner set of square blocks, each of said blocks being of successively decreasing size and equal height to be stacked in telescopic pyramidal shaped order on said post to form a rigid central body of stepped formation; a plurality of LDR's placed on a central-middle position along all the four side and over the exposed base area of each square block, including a single LDR, centrally disposed over the topmost square block; wherein the step formed walls adjacent to the respective LDR's act as a light blocking member for each LDR and thereby provides a differential output based of respective illumination from the exposed sunlight; and wherein the output of LDR's of each side and the output of the centrally disposed LDR are compared and processed for effective calculation of the sun position.

Inventors:
CHANDRASEKHAR NAGASANDRA SHANKAR RAO (IN)
Application Number:
PCT/IN2017/000090
Publication Date:
November 02, 2017
Filing Date:
April 24, 2017
Export Citation:
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Assignee:
AGARWAL REEMA (IN)
International Classes:
G01S3/786; H01L31/054; H02S20/32
Domestic Patent References:
WO2010065794A22010-06-10
WO2012014236A12012-02-02
Foreign References:
US4225781A1980-09-30
US3390848A1968-07-02
MA23140A11994-10-01
US20080128586A12008-06-05
US20140264700A12014-09-18
Attorney, Agent or Firm:
DASWANI, Bharat (IN)
Download PDF:
Claims:
WHAT CLAIMED IS:

1. A sun position detector assembly comprising:

a square base member ( for better cross direction isolation) a rigid post extending vertically from said base member; a single inner set of square blocks, each of said blocks being of successively decreasing size and equal height (thickness with conforming in size and configuration to the outer periphery of the corresponding step portion and having an opening of the same size configured to allow said blocks to be stacked in telescopic pyramidal shaped order on said post to form a rigid central body of stepped formation with the largest block engaging said base member and wherein the height of the blocks are equal to the step width; a plurality of LDR's placed on a central middle position along all the four side and over the exposed base area of each square block including a single LDR, centrally disposed over the topmost square block; and wherein the LDR's of each side (north/south/east/west, X-Y) are connected in parallel separately for each direction / axes;

wherein the step formed walls adjacent to the respective LDR's, act as a light blocking member for each connected LDR and thereby provides a differential output based of respective illumination / activation from the exposed sunlight; and wherein;

the output of LDR's of each side and the output of the centrally disposed LDR are compared and processed for effective calculation of the sun position using a processing system.

2. The sun position detector assembly as claimed in claim 1 , wherein the said detector is configured for no discontinuity in the position detection of the sun irrespective of any LDR failure in the array.

3. The sun position detector assembly as claimed in claim 1 , wherein the position of sun can be grey coded for the range and accuracy.

4. The sun position detector assembly as claimed in claim 1 , wherein the said detector is further configured for null seeking tracking as discontinuous boundaries poses the hunting problem in the control loop. i The sun position detector assembly as claimed in claim 1 , wherein the array of LDRs in each quadrant are connected so that the output is maximum in the orthogonal position of the said detector ensuring the high signal to noise ratio.

The sun position detector assembly as claimed in claim 1 , wherein the LDRs are connected in parallel so that the dynamic range of the sensing the sun position is maximum with high level of contrast ensuring seamless analog output.

The sun position detector assembly as claimed in claim 1 , wherein the sun position is estimated by equation:

Sun position_EW =(V_east-V_west)/(V_east+V_west) . irrespective of sun's intensity.

Sun position_NS=(V_north_V_South)/(V_North+V_South)

8. The sun position detector assembly as claimed in claim 1 , wherein the sensor is configured for a field of view of the sensor in North, south, east, west directions are divided into 8 grey levels.

9. The sun position detector assembly as claimed in claim 1 , wherein the width of the LDR base (step base width) is a function of cos 12.5° .

10. The sun position detector assembly as claimed in claim 1 , wherein the height of the LDR barrier wall corresponds to sin 12.5 ° .

1 1 . The sun position detector assembly as claimed in claim 1 , wherein the total sum of each block as the sensor is vertically grown to reach to 90° and thereby satisfying the functional requirement.

12. A method for detecting the sun position in real time using three dimensional four quadrant sun position detector configured for aligning the orientation (azimuth and elevation / X and Y) of a solar .power generator with the

2 direction of the light coming from the sun employing detector assembly claimed in any of the preceding claims.

3

Description:
SUN POSITION DETECTOR AND METHOD OF SENSING SUN POSITION FIELD OF INVENTION

The present invention generally relates to sun position detector and method of sensing sun position. More particularly the present invention also concerns a method for sun sensing, that is for aligning the orientation (azimuth and elevation) with a solar tracking system comprising a LDR's with the direction of the light coming from the sun. The disclosed invention encompasses a comprehensive multistage CPV solution with continuous closed loop, feedback controlled, automated, remotely controlled, dawn to dusk and over the complete year sun sensing and tracking system with a provision of peaking the efficiency in terms of concentration collection, generation and power transportation.

BACKGROUND OF THE INVENTION

Solar position detector is a device which follows the movement of the sun as it moves from the east to the west every day. The main function is to provide two or four degrees of freedom in movement. The sensors are used to keep solar collectors/solar panels oriented directly towards the sun as it moves through the sky every day. Using solar trackers increases the amount of solar energy which is received by the solar energy collector and improves the energy output of the heat/electricity which is generated. Solar sensors and trackers can increase the output of solar panels multi-fold with CPV which improves the economics of the solar panel project. The energy contributed by the direct beam drops off with the cosine of the angle between the incoming light and the panel. The sun travels through 360 degrees east-west a day, but from the perspective of any fixed location the visible portion is 180 degrees during a 1/2 day period. Local horizon effects reduce this somewhat, making the effective motion about 150degrees. A solar panel in a fixed orientation between the dawn and sunset extremes will see a motion of 75 degrees on either side, and thus, according to the table above, will lose 75% of the energy in the morning and evening. Rotating the panels to the east and west can help recapture these losses. A tracker rotating in the east-west direction is known as a single-axis tracker. The sun also moves through 46 degrees north-south over the period of a year. The same set of panels set at the midpoint between the two local extremes will thus see the sun move 23 degrees on either side, causing losses of 8.3% A tracker that accounts for both the daily and seasonal motions is known as a dual-axis tracker. .-

The two basic types of active solar tracker are single-axis and double-axis.

The single axis tracking systems realizes the movement of either elevation or azimuth for a solar power system. Which one of these movements is desired, - depends o the technology used on the tracker as well as the space that it is mounted on. For example the parabolic through systems utilize the azimuthally tracking whereas the many rooftop PV-systems utilize elevation tracking because of the lack of space. A single-axis tracker can only pivot in one plane - either horizontally or vertically. This makes it less complicated and generally cheaper than a two-axis tracker, but also less effective at harvesting the total solar energy available at a site. Trackers use motors and gear trains to direct the tracker as commanded by a controller responding to the solar direction. Since the motors consume energy, one wants to use them only as necessary. Single axis trackers have one degree of freedom that acts as an axis of rotation. There are several common implementations of single axis trackers. These include horizontal single axis trackers (HSAT) and vertical single axis trackers (VSAT).

A horizontal-axis tracker consists of a long horizontal tube to which solarmodules are attached. The tube is aligned in a north-south direction, is supportedon bearings mounted on pylons or frames, and rotates slowly on its axis to followthe suns motion across the sky. This kind of tracker is most effective at equatorial altitudes where the sun is more or less overhead at noon. In general, it is effectivewherever the solar path is high in the sky for substantial parts of the year, but forthis very reason, does not perform well at higher latitudes. For higher latitude, avertical-axis tracker is better suited. This workswell wherever the sun is typicallylower in the sky and, at least in the summer months, the days are long.

The Dual axis trackers have two degrees of freedomthat act as axes of rotation. Double-axis solar trackers, as the same suggest, ca . nrotate simultaneously in horizontal and vertical directions, and so are able topoint exactly at the sun at all times in any location. Dual axis tracking systems realize movement both along the elevation- andazimuthally axes. These tracking systems naturally provide the best performance, given that the components have high enough accuracy as well.

In the prior art, an US application US2008/0128586 to Johnson et al. discloses a sun sensor assembly having an aperture that defines an area that is less than the area of the photo-detecting surface of a corresponding first photo-detector. According to another aspect, the invention also includes a solar concentrator includes at least two sun sensor assemblies mounted on the concentrator in a manner to help the solar concentrator track the sun. According to another aspect, the invention also includes a method of processing electrical signals from two or more photo-detectors. According to yet another aspect, the invention includes a sun tracking system that includes a solar panel that includes a solar concentrator and control system.

In another prior art, an US application US2014/0264700 to Janson et al. discloses monolithic sun sensors, assemblies thereof, and methods of making and using same. Under one aspect of the invention, a monolithic sun sensor includes a photo sensor; a spacer material disposed over the photo sensor; and a patterned mask disposed over the spacer material and defining an aperture over the photo sensor. The spacer material has a thickness selected such that the patterned mask casts a shadow onto the photo sensor that varies as a function of the monolithic sun sensor's angle relative to the sun. The sun sensor may further include a substrate in which the photo sensor is embedded or on which the photo sensor is disposed. The spacer material may be transparent, and may include a layer of inorganic oxide, or a plurality of layers of inorganic oxide. The patterned mask may include a conductive material, such as a metal. The aperture may be lithographically defined, and may be square. The sun sensor may further include a transparent over layer disposed over the patterned mask.

In yet another prior art, a PCT specification WO2012/014236 to Rossi et al. discloses quadrant photo detector and related method for sun tracking. The disclosed quadrant photodetectorhas four photosensor arrangedin quadrature and an opaque mask arrangedat a predefined distance fromthe photosensor and it extends fromthe center of the photodetector untilcovering, in a top view, about half thearea of each photosensor. Such aquadrant photodetector is very costeffective and it allows a. high spatialresolution in a specific angle rangeand it is able to give useful informationin a wider angle range. A very efficientmethod for sun tracking can beassociated to the above photodetector.

SUMMARY OF THE INVENTION

The present invention provides a three dimensional 2- axis 4-quadrant sun position detector and method of sensing sun position in real time propose a detector using an array of LDR's which is simple and cost effective and allows at the same time a great accuracy in a specific tracking angle range while maintaining a level of precision and accuracy sufficient for CPV's and systems.

Another object of the present invention is to propose a new and improved method including processing of electrical signals from a plurality of LDR's that select a signal before further downstream processing (e.g., by a microprocessor) which is also referred to as common signal processing chains. Advantageously, such methods can minimize sensing errors from bias sources such as component mismatching, thermal drift, and/or drift associated with component lifetime.

In an exemplary embodiment there is provided a sun position detector assembly comprising a square base member; a rigid post extending vertically from said base member; a single inner set of square blocks, each of said blocks being of successively decreasing size and equal height (thickness with conforming in size and configuration to the outer periphery of the corresponding step portion and having an opening of the same size configured to allow said blocks to be stacked in telescopic pyramidal shaped order on said post to form a rigid central body of stepped formation with the largest block engaging said base member and wherein the height of the blocks are equal to the step width ;a plurality of LDR's placed on a central middle position along all the four side and over the exposed base area of each square block including a single LDR, centrally disposed over the topmost square block; and wherein the LDR's of each side (north/south/east/west, X-Y) are connected in parallel separately for each direction/axes;wherein the step formed walls adjacent to the respective LDR's, act as a light blocking member for each connected LDR and thereby provides a differential output based of respective illumination / activation from the exposed sunlight; and whereinthe output of LDR's of each side and the output of the centrally disposed LDR are compared and processed for effective calculation of the sun position using a processing system.

According to another aspect of the present invention, a method of processing electrical signals from plurality of LDR's includes providing plurality of LDR'sin four sets that generate an electrical signal indicative of theamount of incident light upon the each set of parallely connected LDR's; selectingone electrical signal from among one of the set of the electrical signals generatedby the plurality of LDR's and conditioning theselected electrical signal in a manner so as to provide anunbiased electrical signal.

According to another aspect of the present inventions solar power generatorsystem includes a solar panel that includesa solar concentrator positioned on the solar panel in a mannersufficient to track the sun along an axis and a sun position detector assembly positioned on the solar concentrator in a manner sufficient to track the sun along an axis. The sun position detectorassembly includes a plurality of parallel connected LDR's and a controlsystem. Each LDR generates an electrical signalindicative of the amount of incident light upon each respective LDR. The control system is in electrical communicationwith a solar concentrator such that the control systemcan receive and send electrical ' signals in a manner to help thesolar concentrator track and face the sun for highest output. The controlsystem includes logics program that include selectingone electrical signal from among the electrical signals generated by the four sets of LDR's and conditioning theselected electrical signal in a manner so as to provide anunbiased electrical signal.

The present invention proposes a schematic approach which works as closed loop, feedback controlled, automated, remotely controlled, dawn to dusk and over the complete year sun sensing and a followed tracking system. The system of the illustrative embodiments of the present invention combines highly concentrated solar energy collection, power generation and transmission technologies with a multistage CPV solar power system in a 3D-c ' onfiguration for compact and modular implementation in field deployed, portable roof top and building-integrated applications.

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 without departing from the spirit and scope of the invention as claimed.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig 1 illustrates the basic block diagram of sun position detector in accordance with the present invention;

Fig 2 (a) illustrates a schematic top view of the sun position detector with square base in accordance with the present invention; .

Fig 2 (b) illustrates a schematic side plan view of the sun position detector with square base in accordance with the present invention;

Fig 3 illustrates circuit diagrams of the LDR's of sun position detector for sensing the presence and direction of sunlight (Analog and Digital)in accordance with the present invention;

Fig 4 illustrates a flowchart of the LDR's of sun position detector for sensing the presence and direction of sunlight in accordance with the present invention;

DETAILED DESCRIPTION

The embodiments of sun position detector for use with multistage reflective concentrated photo voltaic (CPV) power generation system and the method thereof such as herein described is selected systems selected for the purpose of illustrating the invention. In general, India has a relatively long sunny day for more than ten months and partly cloudy sky for most of the days of the rest two months. This makes our country, especially the desert sides in the west, which include Rajasthan, Gujarat, Madhya Pradesh etc. very rich in solar energy. Many projects have been done on using photovoltaic cells in collecting solar radiation and converting it into electrical energy but most of these projects did not take into account the difference of the sun angle of incidence by installing the panels in a fixed orientation which influences very highly the solar energy collected by the panel. As we know that the angle of inclination ranges between -90°after sun rise and +90°before sun set passing with 0°at noon. This makes the collected solar radiation to be 0% at sun rise and sun set and 100% at noon. This variation of solar radiations collection leads the photovoltaic panel to lose more than 40% of the collected energy.

The position of the sun is decided by two angles inspherical coordinates; the Altitude angle which is the angle of the sun in thevertical plane in which the sun lies, and the

Azimuth angle which represents theangle of the projected position of the sun in the horizontal plane. These twoangles will be discussed deeply later in this document.

The solar radiations falling on the solar cell array will be maximumwhen the angle of incidence on the panel is 0°which means that the panel isperpendicular to the sun.FIG. 1 shows a block schematic diagram of the proposed system for use with multistage CPV system for concentrating and transforming solar energy into electrical energy.

The proposed system as referred to in the prior application of the same applcant includes a parabolic concentrator configured for reflecting all hitting solar insolence to its focal point which is collected and further concentrated by a secondary concentrator and thereafter exposed to a solar panel configured for efficient conversion of concentrated solar insolence to equivalent electrical power. The system further includes a sun sensing and sun tracking 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 detector is mounted on disclosed multistage concentrated photo voltaic system for real time sensing and tracking of sun round the clock over the year continuously. The system also includes thermal management solution and power transfer solution discussedin subsequent applications configured for cooling the system and further transferring the generated power for onward transmission and /or storage.

LDR'S:- LDR's are light dependent devices whose resistance is decreased when light falls on them and that is increased in the dark. When a light dependent resistor is kept in dark, its resistance is very high. This resistance is called as dark resistance. It can be as high as 10 1Z Ω and if the device is allowed to absorb light its resistance will be decreased drastically. If a constant voltage is applied to it and intensity of light is increased the current starts increasing. The LDR's are less sensitive but more stable and long lasting with relatively contant output performance than photo diodes and photo transistor and for that reason are used herein in the form of an array. SUN POSITION DETECTOR

■ The sun position detector assembly herein disclosed and shown in Fig 2 comprises of a square base member. From the centre of the square base member, a rigid post is provided extending vertically from said base member. Over the square base member a plurality of single inner set of square blocks, each of said blocks being of successively decreasing size and equal height and thickness with conforming in size and configuration to the outer periphery of. the corresponding step portion are placed. These blocks are having an opening of the same size in the centre and configured to allow said blocks to be stacked in telescopic pyramidal shaped order on said post to form a rigid central body of stepped formation with the largest block engaging said base member and wherein the height of .the blocks are equal to the step width. A plurality of LDR's forming an array are placed on a central middle position along all the four side and over the exposed base area of each square block including a single LDR, centrally disposed over the topmost square block. The LDR's of each side (north/south/east/west, X-Y) are connected in parallel separately for each direction / axes. The step formed walls adjacent to the respective LDR's, act as a light blocking member for each connected LDR and thereby provides a differential output based of respective illumination / activation from the exposed sunlight. The output of LDR's of each side (N/S/E/W) and the output of the centrally disposed LDR (C) are compared and processed for effective calculation of the sun position using a processing system. '

The 3D sun sensor herein disclosed is a sun position and sun intensity detection device, which comprises of four adjacently positioned LDR area detectors including parallely connected array of LDR's, positioned in each quadrant of the 2π plane with a blocking vertical plane (mask) to eack LDR as discussed above in order to maximise the contrast output during large deviation of sun positions between X_X and Y_Y planes as shown in Fig 2 and 3. The presence or absence of the sun position (analog and 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:

sin e c = 1/CR_L

X = distance of x axes LDR from centre

Y = distance of y axes LDR from centre

Z = height.of barrier.

The ratio of Z/X=tan θ ε Similarly Z/Y=tan G c where x and y are the position of sensors in X-Y plane and Z is the height of barrier. Noise immunity, has been effectively taken care of with customization of the height of the barrier and further with the use of plane glass fitted LDR, thereby providing a high CMRR.

2Π SUN POSITIO DETECTOR 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 theLDR_West. 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 in east-west is detected by acquiring the signal voltages (V_East and V_West). By calculating ratio of (V_East - V_West) / ( V_east + V_West). The SUN position in north south is detected by acquiring the signal voltages (V_North and V_South). By calculating ratio of (V_North - V_South) / ( V_North + V_South).

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

As per the discussed embodiment the four different arrays of parallely connected LDR Sensor's positioned in four quadrants as shown in Fig 2 is used to sense the light and if the sun changes its position then respective LDR Sensor senses the proportionate change in the light falling on them and generate a proportionate representative Voltage signal and the said voltage signal fed to the comparator IC. All Voltage signal of the each array of LDR sensorsincluding the output of the centrally disposed LDR are compared by a microprocessor / comparator are fed to the microcontroller as shown in Fig 3. The stepwise positioned LDR's present in all the directions are connected in parallel as shown in Fig 3. The output of the parallel connected LDR's in each direction is represented as LDR N, LDR S, LDR E, LDR W and the output of the centrally disposed LDR is represented as LDR Ref respectively. The output of the LDR's are FED to a Conditioner and Error amplifier circuitfor correction of any presence of noise in the signal strength. The error free signal is fed to a controller (microcontroller) for evaluation. Microcontroller receive the voltage signal from the any i/o pin of the microprocessor/comparator and compares the each LDR array output signal with corresponding each LDR sensor output. The comparison is done with opposite side sets of LDR's like (East - West and North - South) and fed to the servo motor actuators configured for the real time alignment of the solar concentrator assembly in the direction of the sun through a limit switch. When the controller find the Highest voltage level of any LDR sensor, then it gives the instruction to the motor actuator through the motor actuator driver circuit to rotate the so!ar panel on the single axis in the direction of the LDR sensor which are generating highest voltage output. The activation of the motor actuator is stopped immediately when the difference in the output of the arrays of LDR's is '0' or Nil. By using external ' two motor actuator and by making connection in parallel we can move the soiar concentrator assembly in any direction. As by rotating the solar panel in the direction of the sun we utilize the maximum energy of the sun.

BARRI ER HEIGHT AND LOGICS

According to an aspect of the present invention, there is provided four sets of array of LDR's mutually connected in parallel " and separate for each direction including (north, south, east and west)comprising four photosensitive areas placed on a surface, each photosensitive area comprising a set of paralely connected LDR's adapted to produce a signal in response to a light beam incident thereon with said signals being useful to calculate a direction of said incident light beam, and comprising an adjacently disposed opaque mask to each exposed LDR for casting a shadow on said LDR, said LDR being characterized in that said opaque mask is arranged in order to mantain a predetermined distance away from said LDR , said opaque mask being shaped and sized so that, in a top view, it occludes a predetermined percentage of each photosensitive area.

As it is known by a skilled person and also discussed in the prior art that the output signals of two LDR's / photosensors (photosensitive , areas) arranged on a flat surface can be used to track a light beam incident thereon along one direction; an array of three or more photosensors anyway arranged on a surface can be used, by providing a proper calculation algorithm, to track a light beam incident thereon along two (perpendicular) directions in the plane. Advantageously, in a particularly efficient and cost effective layout for performing tracking of a light source along two directions, the four sets of array of parallely connected LDR's used is a quadrant photo sensor comprising a plurality of photosensitive areas in all four directions arranged in quadrature on a equi-stepped surface, wherein each photosensitive area comprising at least one LDR element adapted to produce a signal in response to a light beam incident thereon with said signals being read in pairs to calculate a X and Y directions of said incident light beam, ' and said opaque mask extends to each adjacently placed LDR of said quadrant photodetector up to occlude a predetermined same percentage of each photosensitive area.

The particular design of the sun position detector architecture allows a comparably greateraccuracy with respect to the prior art in a little angle range but it provides sun direction information in a wide angle range: ± 90" on all four directions with respect to the central axis, in order to find the solar position starting from any initial tracker position. This feature is useful in the first tracking system initialization or after an energy blackout. In fact, the above allows a quicker installation process as there is no need of performing an accurate alignment of the sun tracking system during installation.

Following are the exemplary features which are the distinguishing and synergestic effect for establishing inventivess over the discussed prior art:

1. No discontinuity in the position detectionirrespective of any LDR failure in the array;

2. The position of sun can be grey coded for the range and accuracy.

3. As the sun position detection assembly system is a null seeking tracker discontinuous boundaries poses the hunting problem in the control loop.

4. Since the LDRs are connected in parallel as shown in Fig 3, the output will be maximum in the tracked position ensuring the high signal to noise ratio.

5. As the LDRs are connected in parallel the dynamic range of the sensing the sun position is maximum with high level of contrast. Also ensures seamless analog output.

6. The output of the sun position detector can be used in digital mode with 7 bit accuracy or it can be in analog mode with dynamic range extending many folds .

The sensor availability reliability and continuous mode of sensing the sun position will be greatly extended. The sensor also can be used for detecting sun rise and sun set conditions with appropriate technique. The sun position can be estimated by equation: Sun position_EW =(V_east-V_west)/(V_east+V_west) . irrespective of sun's intensity.

Sun position_NS=(V_north_V_South)/(V_North+V_South) Sun's intensity can be estimated by equation (V_east+V_west) and compare with threshold levels

Sun's intensity can be estimated by equation (V_North+V_ South) and compare with threshold levels Design of the XY positions for the sensor.

The field of view of the sensor if 90° in North, south, east, west directions are divided into 8 grey levels.

i.e. 90/7= 12.5 ° .

The width of the LDRbase (step base width) is a function of cos 12,5°

The height of the LDR barrier wall corresponds to sin 12.5 ° .

The total sum of each block as the sensor is vertically grown reached to 90° and thus satisfying the functional requirement. The features of the LDR sensor is the sensor output which is continuous function.The sun position detector can be used in analog mode or digital mode.The sensor output will be maximum in sun orthogonal position hence improving the signal to noise -ratio and has a large dynamic range and no boundary limitations as posed by the slit sun sensors.

According to another aspect of the present invention, there is also disclosed a method for detecting the sun position ih real time using three dimensional four quadrant sun position detector configured for aligning the orientation (azimuth and elevation / X and Y) of a solar power generator with the direction of the light coming from the sun, said system comprising a horizontal support member parallel to the horizontal axis of the solar power generator where the disclosed sun position detctor is firmly mounted, a processing unit for processing data from the sun position detector and controlling a drive mechanism comprising a first actuator for horizontal sweeping (azimuth) and a second actuator for vertical sweeping (elevation), the processing unit controlling said first and second actuators according to X and Y position values calculated based upon the outputs of sun position detector, said sun position detector comprising an array of LDR's mutually connected in parallel and separate for each direction including (north, south, east and west)comprising four photosensitive areas placed on a surface, each photosensitive area comprising a set of parallely connected LDR's adapted to produce a signal in response to a light beam incident thereon with said signals being useful to calculate a direction of said incident light beam, and comprising an adjacently disposed opaque mask to each exposed LDR for casting a shadow on said LDR, said LDR being characterized in that said opaque mask is arranged in order to mantain a predetermined distance away from said LDR , said opaque mask ' being shaped and sized so that, in a top view, it occludes a predetermined percentage of each photosensitive area, said X and Y position values being each calculated by said processing unit according to output values from the array of LDR's of at least two different quadrants with a readout per pair. The reference voltage may be drawn with the full exposed and centrally disposed LDR. Further the said method being further characterized by a condition that when said processing unit is not able to perform the calculation of said X and Y position because of a too great misalignment of said quadrant photodetector relative to the sun, it uses output information from the illuminated LDR's of the exposed photosensitive areas with respect to the centrally disposed LDR for initiating the action of determining which is the .direction where said first and/or second actuators have to be operated in order to realign said sun position detector, and it consequently operates said first and/or second actuators until it is able again to perform the calculation of said X and Y positions. Basically the algorithm as shown in Fig 6 is based on the difference calculation, but each time the tracker alignment is out of the acceptable tolerance, the four ' quadrant sun position detector gives the right signal in order to correct the future trajectory.

Once the LDR's symmetry axis has been aligned to the sun, the power produced by an associated solar power generator is monitored by operating said first and second actuators, in order to find the Xpmax and Ypmax values which maximize the energy produced by said solar power generator.

Control Algorithms and logics as shown in Fig 4

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 limits;

e) First North_South movement is performed till the peak position reached. f) After the North_South movement is stopped, East _West direction movement is accomplished;

g) Step e and f will be repeated till the. position error reaches below the threshold is detected.

The 2TT 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 LDRJ ast should not illuminate the LDR_West. 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 - V_west) / ( V_east + V_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 collects the sunlight orthogonal to a tracked moving plane in 2π 4 quadrant positioning system with feedback control.

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 shou ld 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.