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Title:
LOW COST SINGLE AND DUAL-AXIS SOLAR TRACKER APPARATUS AND METHOD
Document Type and Number:
WIPO Patent Application WO/2018/025277
Kind Code:
A1
Abstract:
The invention described herein provides electrically and electronically controlled single and dual axis solar tracking apparatus. The apparatus works on solid or fluid / liquid weight displacement principle. It is simple, economic, low cost, less noisy compared to all existing Solar trackers and can be easily installed both by Industries and residents. The parts or components of solar tracker are easily accessible and replaceable and are inexpensive making it a low maintenance solar tracker. The invention further provides an automatic method of tracking Sun using the said solar tracking apparatus.

Inventors:
NIMBALKAR, Shrikant (Swami Bunglow plot. No- 5, Bhagwa ChowkAshtavinayak Nagar, Shivaji Nagar ,Jail Roa, Nasik Road Nasik 1, 422101, IN)
NIMBALKAR, Kedar (Swami Bunglow plot. No- 5, Bhagwa ChowkAshtavinayak Nagar, Shivaji Nagar ,Jail Roa, Nasik Road Nasik 1, 422101, IN)
Application Number:
IN2017/050314
Publication Date:
February 08, 2018
Filing Date:
July 29, 2017
Export Citation:
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Assignee:
NIMBALKAR, Shrikant (Swami Bunglow plot. No- 5, Bhagwa ChowkAshtavinayak Nagar, Shivaji Nagar ,Jail Roa, Nasik Road Nasik 1, 422101, IN)
NIMBALKAR, Kedar (Swami Bunglow plot. No- 5, Bhagwa ChowkAshtavinayak Nagar, Shivaji Nagar ,Jail Roa, Nasik Road Nasik 1, 422101, IN)
International Classes:
F24J2/46
Foreign References:
US20080011288A12008-01-17
CN202711071U2013-01-30
US20090260618A12009-10-22
US20140124015A12014-05-08
US4305380A1981-12-15
US8904774B22014-12-09
Attorney, Agent or Firm:
KHARKAR, Pallavi et al. (IPRAM Intellectual Property Services, 716 Swastik Disa Corporate Park,L.B.S Marg, Ghatkopar, Mumbai 6, 400086, IN)
Download PDF:
Claims:
Claims

A solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus comprising solar energy collector device which moves by an automatic weight displacement mechanism.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 1 comprising following components

i) solar energy collector device along with its mounting assembly ii) sensor assembly

iii) processing element

iv) motor driver

v) weight displacement system.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 having Solar energy collector device along with its mounting assembly comprising of following components

i) solar energy collector device

ii) solar energy collector device mounting frame

iii) support structure

iv) means of providing freedom of movement to Solar Energy collector device.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 having sensor assembly comprising of following components

i) East- West and / or North-South Solar Position tracking sensors in the nature of light based position sensors or GPS sensor assembly. ii) Motion sensors to fetch one or more of tilt angles, acceleration, angular velocity of solar energy collector device along X and Y axis iii) light intensity sensor and optionally,

iv) wind sensor.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 4 wherein the light-based position sensors are light sensitive elements comprising one or more of the following

a) LDR (light dependent resistor)

b) Photodiode

c) Photo Transistor

d) Solar cells.

and these light sensitive elements are arranged in configuration selected from i) voltage divider configuration ii) series configuration iii) anti series configuration.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 4 wherein the light-based position sensors are light sensitive elements comprising complementary metal oxide semiconductor image sensor (cmos) and such sensor is arranged in standalone configuration.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 wherein the processing element is analog processing circuit or digital processing circuit.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 7 wherein the digital processing circuit is a microcontroller or a microprocessor. The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 wherein weight displacement system is either solid weight displacement system wherein solid is sand or gravel or a solid container containing liquid or a liquid weight displacement system wherein liquid is water or oil or any suitable liquid.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 9 having liquid weight displacement system comprising of following components

i) Four storage containers in following configuration. East direction, West Direction, South direction and North direction for dual axis tracker

Or

i) Two storage containers in following configuration East direction and West Direction for a single axis tracker,

ii) Pipes or tubes connecting East and West storage containers to each other and / or South and North storage containers to each other, iii) A pump in each storage container or single pump for transferring weight from it to the other storage container connected with it through tube / pipe,

iv) Optionally One way / non-return valve / solenoid valve fitted to tube / pipe of storage containers.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 9 having solid weight displacement system comprising one of the following:

a. Archimedes Screw Pump system or an air pump system

b. scissors plate assembly/scissor weight displacement system c. angular weight displacement system d. linear actuator weight displacement system

e. Trammel of Archimedes weight displacement system

e. pulley weight displacement system

f. roller weight displacement system

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 11 having scissors plate assembly/scissor weight displacement system as solid weight displacement system comprising solid weight, specific arrangement of scissor plates, lead screw arrangement with lead screw and threaded nut and a bi-directional motor wherein upon activation of bi-directional motor, specific arrangement of scissor plates and lead screw arrangement together acting as weight moving mechanism moves solid weight thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 11 having angular weight displacement system as solid weight displacement system comprising solid weight , angular moving arrangement of weight displacement rod or weight displacement arm and a bi-directional motor wherein upon activation of the bi-directional motor, angular moving arrangement of weight displacement rod or weight displacement arm acting as weight moving mechanism moves solid weight thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 11 having linear actuator weight displacement system as solid weight displacement system comprising solid weight, leadscrew actuator or multilink actuator, threaded nut or travelling nut and a bi- directional motor wherein upon activation of the bi-directional motor, lead screw actuator or multilink actuator, threaded nut or travelling nut together acting as weight moving mechanism moves solid weight thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 11 having Trammel of Archimedes weight displacement system as solid weight displacement system comprising two solid weights, rod which is attached to two weights by pivots and a bidirectional motor wherein upon activation of the bi-directional motor, two weights, the rod attached to the weights by pivots together acting as weight moving mechanism moves solid weight thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 11 having pulley weight displacement system as solid weight displacement system comprising solid weight, gears, pulley chain and a bi-directional motor wherein upon activation of the bidirectional motor, gears and pulley chain together acting as weight moving mechanism moves solid weight thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 11 having roller weight displacement system as solid weight displacement system comprising solid weight, rollers, weighted sheet and a bi-directional motor wherein upon activation of the bidirectional motor, rollers and weighted sheet together acting as weight moving mechanism moves solid weight thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

18. The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claims 12-17 wherein the weight moving mechanism comprising one or more of bearings, movement channel, weight displacement channel.

19. The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 9 having solid weight displacement system comprising solid weight, weight moving mechanism to move the solid weight and a bidirectional motor initiating weight moving mechanism and thereafter movement of a solid weight. 20. The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 9 having solid weight displacement system comprising solid weight capable of moving in linear or angular direction to and fro upon activation of bi-directional motor and weight moving mechanism.

21. The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 9 having solid weight displacement system comprising solid weight capable of moving in linear or angular direction to and fro upon activation of bi-directional motor and weight moving mechanism and thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

22. The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 comprising a processing element which i) receives signal from sensor assembly, ii) processes the signal and iii) further instructs electrical switching circuit to switch on or switch off which when switched on further activates weight displacement pump thereby causing or preventing weight displacement.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 comprising a processing element which

i) receives signal from sensor assembly,

ii) processes the signal and

iii) further instructs bi-directional motor driving circuit one of the following:

i) to move in a clockwise direction or

ii) to move in an anticlockwise direction or

iii) not to move in any direction.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 23 comprising a processing element which i) receives signal from sensor assembly, ii) processes the signal and iii) further instructs bi-directional motor driving circuit to move in clockwise direction or to move in an anticlockwise direction thereby activating weight moving mechanism to move solid weight linearly or angularly thereby causing movement or tilting or repositioning of Solar energy collector device in desired direction.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 further comprising a counterbalance Spring mechanism that helps to move solar energy collector device in a Sun path naturally and providing greater stability against winds and thereby reducing on time of motors leading to low energy consumption for solar tracking.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 further comprising incorporating counter balance spring or counterbalance weight to allow natural movement of solar energy collector device in Sunpath.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 2 further comprising a braking system to stop energy collector device in case of excessive wind or excessive motion or accidental triggering.

The solar tracking apparatus comprising electrically and electronically controlled single or dual axis solar tracking apparatus of claim 27 wherein the braking system comprises one of the following i) inertial braking system,

ii) chain braking system

iii) gear braking system.

iv) combination of inertial braking system and chain braking system v) combination of inertial braking system and gear braking system.

Process of tracking Sun along X axis (East West direction) using solar tracking apparatus comprising electrically and electronically controlled single axis solar tracking apparatus or Process of tracking Sun along X axis (East West direction/ azimuth) and Y axis (North South direction/ altitude) using solar tracking apparatus comprising electrically and electronically controlled dual axis solar tracking apparatus comprising following steps

i) Fetching essential predefined parameters,

ii) Reading one or more of a) light based position sensor value b) angular position sensor value and c) lux sensor value, iii) Comparing sensor values with standard values.

iv) Performing one of the following actions

a) if required, automatically activating associated switching circuit and b) thereafter motor to activate pump to cause weight transfer from associated storage container to connected other storage container and thereby repositioning solar energy collector device due to shift in the center of gravity of solar energy collector device as a result of weight displacement;

c) if required, turning off one or more pumps thereby preventing transfer of weight.

Process of tracking Sun along X axis (East West direction) using solar tracking apparatus comprising electrically and electronically controlled single axis solar tracking apparatus or

Process of tracking Sun along X axis (East West direction/ azimuth) and Y axis (North South direction/ altitude) using solar tracking apparatus comprising electrically and electronically controlled dual axis solar tracking apparatus comprising following steps

i) fetching essential predefined parameters using GPS sensor assembly,

ii) feeding essential fetched parameters in astronomical equation to obtain tracking angle (Tilt Angle and Polar Angle) as well as one or more other parameter(s),

iii) Comparing the present angular position of solar energy collector device with the required tracking position,

iv) Performing one of the following actions

a) if required, automatically activating associated switching circuit and thereafter pump motor to cause weight transfer from associated storage container to connected other storage container and thereby repositioning solar energy collector device due to shift in the center of gravity of solar energy collector device as a result of weight displacement; b) if required, turning off one or more pumps thereby preventing transfer of weight.

Process of tracking Sun along X axis (East West direction) using solar tracking apparatus comprising electrically and electronically controlled single axis solar tracking apparatus or Process of tracking Sun along X axis (East West direction/ azimuth) and Y axis (North South direction/ altitude) using solar tracking apparatus comprising electrically and electronically controlled dual axis solar tracking apparatus comprising following steps

i) Fetching essential predefined parameters,

ii) Reading one or more of a) light based position sensor value b) angular position sensor value and c) lux sensor value,

iii) Comparing sensor values with standard values.

iv) Performing one of the following actions

a) if required, automatically rotating / activating bi-directional motor and activating weight movement mechanism and thereafter moving solid weight to cause shift in weight and thereby causing movement or tilting or repositioning of Solar energy collector device as desired; b) if required, stop rotation of motor / stop activated motor thereby preventing activated weight movement mechanism and thereafter preventing transfer of weight and thereby stopping movement or tilt or repositioning of Solar energy collector device as desired.

Process of tracking Sun along X axis (East West direction) using solar tracking apparatus comprising electrically and electronically controlled single axis solar tracking apparatus or Process of tracking Sun along X axis (East West direction/ azimuth) and Y axis (North South direction/ altitude) using solar tracking apparatus comprising electrically and electronically controlled dual axis solar tracking apparatus comprising following steps i) fetching essential predefined parameters using GPS sensor assembly,

ii) feeding essential fetched parameters in astronomical equation to obtain tracking angle (Tilt Angle and Polar Angle) as well as one or more other parameter(s),

iii) Comparing the present angular position of solar energy collector device with the required tracking position,

iv) Performing one of the following actions

a) if required, automatically rotating / activating bi-directional motor and activating weight movement mechanism and thereafter moving solid weight to cause shift in weight and thereby causing movement or tilting or repositioning of Solar energy collector device as desired; b) if required, stop rotation of motor / stop activated motor thereby preventing activated weight movement mechanism and thereafter preventing transfer of weight and thereby stopping movement or tilt or repositioning of Solar energy collector device as desired.

Description:
LOW COST SINGLE AND DUAL-AXIS SOLAR TRACKER APPARATUS AND METHOD

Field of Invention

The present invention relates to a low-cost single and dual axis solar tracker apparatus and method that tracks the movement of the Sun to optimize the positioning of solar Energy collectors for maximum extraction of energy.

Background of the invention

Solar energy systems using thin film photovoltaic (PV) modules are gaining wide acceptance as a commercial and residential alternate energy source. However, the advantages of such systems are not fully exploited to produce power on a large scale and in a cost-effective manner in terms of cost per watt of power generated and it still remains a challenge. Use of effective tracker that can track the entire path of Sun in all seasons in a cost-effective manner still poses a problem.

It is found that going from a fixed array panel to a single axis solar panel, there is substantial increase in the yearly collection of solar energy around 24 - 32 % which makes the investment worthwhile. However further going to dual axis tracker adds substantial cost and in return increase in yearly collection does not rise substantially (about 4 % increase from single axis.) Further such dual axis tracker that work on linear actuators or similar mechanisms have expensive parts and cost of maintenance is high. The cost of tracker is as high as 50 % cost of the solar panels or even more.

Patent US20140124015 (US9276520(B2)) cover systems and methods for solar energy collection devices, and particularly systems and methods that reposition solar energy collection devices of all types (e.g., flat panel, as well as concentrated photovoltaics), based on, for example, solar tracking or calibration. Such system requires pre-calibration of water flow rate and daily refilling with exact defined amount of fluid and at defined time of the day which is complicated and not user friendly. No stabilizer to the system is provided to stabilize solar panel against wind movement etc. Fluid used is water and it can get contaminated, also due to deposition of salts and minerals, the dripping hole can get blocked and that may cause faulty tracking. In short, daily user attention is required for maintenance. Also, how system can be adopted for dual Axis tracker is not provided.

Thus, there is a need to develop a tracker which is simple, automatic, economical, where all parts are replaceable and easily available and maintenance cost is very low and have an extremely low noise during operation.

Brief description of the drawings:

Fig. 1 represents perspective view of a dual axis solar tracking apparatus.

Fig. 1 A represents dual axis solar panel tracked to East direction

Fig. IB represents dual axis solar panel tracked at noon

Fig. 1C represents dual axis solar panel tracked to West direction

Fig. ID represents solar panel having fluid weight displacement system adopted for dual axis tracking apparatus.

Fig. 2A represents diagrammatic inside view of fluid container of solar tracking apparatus.

Fig. 2B represents perspective view of valve in open position.

Fig. 2C represents perspective view of valve in closed position.

Fig. 3A represents perspective view of a double hinge joint in solar tracking apparatus.

Fig. 3B shows perspective view of counter balance spring mechanism in solar tracking apparatus.

Fig. 3C shows perspective view of chain braking system.

Fig. 3D shows perspective view of gear braking system.

Fig. 4A represents perspective view of Scissors weight displacement system. FIG. 4B represents perspective view of Scissors weight displacement system. Fig. 4C represents perspective view of angular weight displacement system.

Fig. 4D represents angular weight displacement system.

Fig. 4E represents lead screw actuator mechanism for angular weight displacement Fig. 4F represents lead screw actuator mechanism for linear weight displacement Fig. 4G represents alternate lead screw actuator mechanism for linear displacement of weight Fig. 4H represents multi stage actuator system for linear displacement of weight Fig. 41 represents expanded and contracted views of multi stage actuator system Fig. 4J represents lead screw actuator mechanisms for dual axis solar tracker for linear displacement of weights

Fig. 4K represents Trammel of Archimedes weight displacement system.

Fig. 4L represents Trammel of Archimedes weight displacement system.

Fig. 4M represents pulley weight displacement

Fig. 4N represents Roller Weight displacement system

Fig. 5A is a circuit diagram used to control solar tracking apparatus.

Fig. 5B represents standard resistive voltage divider sensor

Fig. 5C represents LDR as a light-based position sensor

Fig. 5D represents photodiodes as sensor

Fig. 5E represents solar cell as sensor

Fig. 6 is a block diagram of circuits used in solar tracking apparatus

Fig 7A is flowchart of the process of repositioning the solar panel along X-axis

(East-West direction) according to Sun's position in the sky.

Fig 7B is flowchart of the process of repositioning the solar panel along Y-axis

(North-South direction) according to Sun's position in the sky.

Fig. 8 is a diagrammatic view of single axis solar tracker setup

Fig. 9 is a diagrammatic view of selected motion tracks of the Sun throughout the year.

Detailed description of Invention

The present invention covers electrically and electronically controlled single and dual axis solar tracking apparatus or solar tracker. The electrically and electronically controlled single or dual axis solar tracking apparatus is one wherein certain components are electrically controlled such as for example, electrical switching circuit and certain other components are electronically controlled such as for example, microcontroller or microprocessor. In one aspect, solar tracker according to the present invention comprises an electrically and electronically controlled single or dual axis solar tracking apparatus comprising following components

1) Solar energy collector device along with its mounting assembly

2) Sensor assembly

3) Processing element

4) Motor drivers

5) Weight displacement system and

6) Optionally a braking system

In an embodiment, the processing element is microcontroller or microprocessor. In another embodiment, the processing element is analog circuit.

In an embodiment, the motor driver is an electric switching circuit or 4 channel relay circuit. In another embodiment, motor driver is an H-bridge motor driver. In one embodiment, weight displacement system involves fluid weight displacement system. In another embodiment, the system is a solid weight displacement system. Fluid weight displacement system preferably employs pump systems. Solid weight displacement systems employ either pump system such as Archimedes Screw Pump system or one of the scissors plate assembly, angular weight displacement, linear actuator weight displacement, pulley weight displacement, roller weight displacement system. Particularly, when solid material is sand or gravel, Archimedes Screw Pump system or an air pump system is employed. When solid weight is other than sand or gravel or other than any pourable solid material, a bi-directional motor is preferred. However, it is understood that bidirectional motor does not limit the scope of invention and any means performing similar function to that of a bi-directional motor can be employed.

Solar energy collector device mounting assembly comprises of following components

i) Solar Energy collector device

ii) Solar energy collector device mounting frame

iii) Support for solar Energy collector and tracker

iv) Means of providing freedom of movement to Solar Energy collector device v) Counter-balance mechanism such as counter balance spring mechanism to provide stability and natural movement of solar collector device in Sun path. Sensor assembly has,

i) East-West (for X axis movement) and North-South sensors (for Y axis movement) in the nature of light based position sensors for dual axis tracker and only East-West sensor in the nature of light based position sensors for single axis tracker

ii) Motion sensor such as for example Angular position sensors to fetch tilt angles of solar panel along X and Y axis in dual axis tracker and Angular position sensors to fetch tilt angles of solar panel along X axis in single axis tracker and

iii) Lux sensor to sense light intensity.

Alternatively, instead of light based position tracking of Sun, it is possible to use data provided from GPS (Global Positioning System) for calculating position of Sun for solar tracking. In this case all the required parameters such as UTC time, date, latitude and longitude of tracker are fetched using GPS. The data so obtained is processed by processing element using astronomical equations and then desired tracking path is calculated. The difference between actual tracker's path and desired tracking path is assessed by processing element and accordingly, if tracking is required, the associated electrical switching circuit is activated and then further associated pump motors will be controlled to achieve the tracking position of Sun. RTC (Real time clock) is connected to the processing element. RTC is used to retain time and date information all the time, even when power is removed / disconnected for some reasons. RTC is initially synchronised from GPS data. It uses an on-board battery to keep time information preserved, so when required, this time information and GPS Data from GPS receiver is used to calculate the tracking information.

Along with GPS sensor assembly, the other two sensors such as angular position sensors and Lux intensity sensors are used.

Sensor board can be connected wirelessly to the control circuit by addition of wireless communication circuitry and interfacing. Processing element can be in the nature of Microcontroller or microprocessor which receives input signal from Sensors assembly and which controls / drives electrical switching circuit according to provided program logic.

When GPS sensor assembly is used, processing element calculates tracking angle (Tilt Angle and Polar Angle) as well as several other parameters such as Declination angle, Equation of time, Hour Angle, Sunset and Sunrise Time, to calculate Starting tracking angle and stop tracking angle in degrees using astronomical equation by feeding essential fetched parameters such as real time and latitude and longitude of tracking apparatus. In the next step, the processing element compares the current angular position of solar device (panel) with the required tracking position and if necessary activates the associated switching circuit and thereafter pumps to cause transfer of weight to achieve tracking.

When GPS sensor assembly is used, required data like UTC time, date, latitude and longitude of tracker are gathered from GPS sensor assembly. The time and date information received from GPS is synchronized with RTC and from then any data required about time & date will be requested from RTC unit as it manages data with high precision. Location information will be stored in free ram that is available on chip. This information is then processed in astronomical equations such as Declination angle, Equation of time, Hour Angle, Sunset and Sunrise Time, Tracking Angle(Tilt Angle and Polar Angle) to calculate Starting tracking angle and stop tracking angle in degrees.

Electrical switching circuit on instructions from microcontroller activates pump present in storage containers. This circuit has i) a transistor and ii) electrically operated switch.

Pump activation circuit or switching circuit receives power through switching element (relay) to get activated and upon activation turn on the pump of a desired fluid storage container to cause transfer of fluid from that container to such other container connected to first container. As an alternative to fluid, solid granular material such as sand or gravel can be used for weight displacement.

Weight displacement system - This system causes movement of panel due to shift in center of gravity. Weight displaced can be solid weight, weight of solid granular material such as gravel or sand or fluid such as water, oil or any other suitable fluid. Weight displaced can be also a weight block displaced by a suitable means. It is understood by the person skilled in the art that anything that can be displaced to cause shift in centre of gravity of solar panel thereby allowing its movement can be used as weight displacement assembly. In solid weight displacement systems, a bidirectional motor is used. This motor is activated by the microcontroller upon receiving signals from sensor assembly. The motor moves in one of the direction and this rotational motion is transmitted to the next component in the system. The system is set into motion and a solid weight makes either a linear or angular motion and travels to another position. This travelling of weight causes tilting of solar panel in the direction of weight. The different such solid weight displacement systems are further described with the help of drawings. It is understood by a person skilled in the art that none of the methods of weight displacement limit the invention but they merely provide few means of weight displacement and can be replaced by any new or existing weight displacement method not discussed here.

In one embodiment, invention relates to a dual axis solar tracking apparatus comprising following parts

1) Solar panel mounted on a supporting frame and supported by a support such as a central supporting pole through a double hinge central joint having degree of freedom to rotate in both X (East - West) and Y (North - South) axis at 160 degrees along each axis. Frame is made up of cast iron but it can be fabricated with any suitable fabrication metals. A counter balance spring connected to the central supporting pole at one end and through connector rod to the solar frame at other end. In other embodiments, alternatively any solar energy collector device such as solar thermal energy collector can be mounted to a solar frame.

2) Sensor assembly - Sensor panel installed with i) East- West and North-South light based position sensors in the configuration of voltage divider and ii) Angular position sensor and iii) Lux sensor. These sensors are interfaced to a microcontroller. As an alternative to light based position sensors in the configuration of voltage divider, solar cells in anti-series configuration are also used and described under alternate embodiment. 3) Weight displacement system, preferably fluid weight displacement system comprising 4 fluid storage containers, 4 pumps with connector tubes connecting East and West fluid storage containers, and top and bottom fluid storage containers having at least 3 non-return valves. In the present embodiment, out of four, three fluid storage containers are hanged from the supporting frame with the hook or any similar arrangement. Out of three non-return valves, preferably two are attached almost vertically at the outlet of pumps present inside East and West fluid storage containers and third one attached almost vertically at the outlet of pump present inside top fluid storage container.

4) Microcontroller or microprocessor which receives input signal from Sensors assembly and which controls / drives electrical switching circuit which in present embodiment is a 4-channel relay circuit according to program logic. Alternatively, other types of switching circuits are described under various other embodiments.

5) Electrical switching circuit which in this embodiment is 4 channel relay circuit) which on instructions from microcontroller activates pump present in fluid storage containers, this circuit has i) a transistor (which in this embodiment is an NPN transistor) and ii) electrically operated switch which in this embodiment is a relay component

6) AC voltage source which directly supplies power to the 4 channel relay circuit (electrical switching circuit) and through AC to DC converting switch mode

Power Supply supplies required DC power to the microcontroller.

Switching elements or switching components is any suitable Semiconductor device that can be chosen depending upon i) nature of voltage source used (AC or DC), ii) Power handling capacity iii) Type of a load and iv) various triggering methods. Alternatively, in above embodiment, instead of fluid weight displacement system, solid weight displacement system can be used. In some case, a solid weight, a bidirectional motor and weight moving mechanism are employed. Electrical switching circuit on instructions from microcontroller activates such bi-directional motor. A solid weight is moved through with the help of bi-directional motor towards or away from it thus tilting the solar panel in East -West direction as desired. In one embodiment, switching components can be any type of Transistor.

In yet another embodiment, it is preferred to use thyristor device as switching components, particularly when voltage source used is AC.

In yet another embodiment, Electromechanical Relay is used as switching component.

In a preferred embodiment water is used as weight displacement fluid but it is possible to use any type of fluid. Fluids with low viscosity are preferred. With the addition of antifreeze solutions in appropriate proportion with fluid, freezing point is reduced and boiling point is increased to the extent where the evaporation can be completely eliminated, which makes system versatile to use in regions with extreme higher and lower temperatures. To stop growth of microorganisms in fluid, biocides / preservatives can be used.

Automatic water inlet system can also be implemented with the help of electrically controlled valves.

In yet another embodiment, any solid granular substance such as Sand or Gravel can be used as means of weight displacement. In this embodiment, instead of regular pump, Archimedes Screw Pump is preferred. This pump has a outer hollow pipe or tube and inner central shaft. Helical blades are attached to the central shaft which move in both the directions with the help of a bi-directional motor. A bi- directional motor is connected to the central shaft for transfer of physical substance from one storage container to other in both direction. For bidirectional movement, either AC or DC motor control circuits are used. H-Bridge circuit is preferred in DC motor control circuit whereas semiconductor switching element is preferred in AC Motor control circuit. As an alternative to Archimedes Screw Pump, air pressure pump can also be used.

In yet another aspect, there are provided methods of tracking Sun using electrically and electronically controlled single or dual axis solar tracking apparatus according to the present invention comprising following components

1) Solar energy collector device along with its mounting assembly

2) Sensor assembly

3) Microcontroller or microprocessor 4) Electrical Switching Circuit

5) Weight displacement system and

6) Optionally a braking system, and

7) Suitable power supply to electrical switching circuit and to the microcontroller / microprocessor.

The method is simple and automatic and no supervision is required. The method involves process of tracking Sun along X axis (East West direction) using dual axis solar tracking apparatus comprising following steps

a) Fetching essential predefined parameters

b) Reading one or more of i) light based position sensor value ii) angular position sensor value and iii) lux sensor value

c) Comparing sensor values with standard values

d) Performing one of the following actions

i) if required, automatically activating associated switching circuit and thereafter pump system causes weight transfer from associated storage container to connected other storage container and thereby repositioning solar energy collector device due to shift in the center of gravity of panel as a result of weight displacement ii) if required, turning off one or more pumps thereby preventing transfer of weight Without limiting the scope of the invention, the preferred embodiments are illustrated with the help of figures 1-9 described hereinafter.

Fluid weight displacement system is described in detail below:

Figure 1 provides perspective view of dual axis solar tracker apparatus. It includes a solar panel 101 mounted on a supporting frame 102. The supporting frame 102 is connected to the central supporting pole 103 with the help of double hinge central joint 300 (also provided in Fig 3a) which provides freedom of movement along both X and Y axis in 160 degrees. A counter balance spring 105 is connected to central supporting pole 103 at one end and central supporting frame 102 at the other end with the help of counter balance connector rod 104. The supporting base structure is fixed or bolted to the ground for better stability.

The solar panel movement is due to shift in centre of gravity of the panel caused by weight displacement phenomenon. The weight displacement is caused by transfer of any solid or fluid material. In this embodiment, weight displacement is caused by transfer of fluid. For the storage of weight displacement fluid, four storage containers are used. Three containers are hanged from supporting frame 102 with the hook 112 or any similar arrangement while bottom container 106 is not attached to the frame. Each container includes a fluid pump. The East (left) and West (right) containers are connected by pipes / tubes to allow transfer of fluid between them, similarly, top (south) and bottom (north) containers are also connected by tube / pipe for transfer of fluid between them. East, West and south containers are provided with non-return valves. Non-return valve normally allow fluid to flow through it in only one direction. The non-return valves stop the transfer / displacement of fluid by inclusion of air flow, once the sufficient fluid is transferred to achieve tracking. Since the bottom container does not offer unexpected fluid flow towards top container as its physical placement is lower than top container, pump in the bottom container doesn't require non-return valve.

The arrangement of container, pump and non-return valve are as follows:

i) The bottom container -106 has pump 1005 but no non-return valve, ii) The top container -107 has pump 1011 and a non-return valve 205 iii) The left container - 108 has pump 1016 and a non-return valve 206 iv) The right container - 109 has pump 1021 and a non-return valve 207. Pump 1011 of the top container 107 is connected to the pump 1005 of bottom container 106 with tube / pipe 110 and pump 1016 of left container 108 is connected to the pump 1021 of right container 109 using pipe 111.

In this embodiment, single phase synchronous AC motor having submersible fluid pumping mechanism of rating 18 watts and having pumping capability of 800 L/H are used which will allow solar panel to move at a rate of l°/second, Alternatively, different motor types can be used.

Light sensor 501 which has an East - West light-based position sensor and a North- South light based position sensor is also shown in the figure.

Figures 1A to 1C provided the solar tracking apparatus when Sun is tracked.

Figure 1A provides solar tracking apparatus that has tracked Sun in the East. Figure IB provides solar tracking apparatus that has tracked Sun in the noon. Figure 1C provides solar tracking apparatus that has tracked Sun in the West. Figs. 1A, IB and 1C provide the perspective view of tracked solar panel. Fig. 1A provides position of tracked panel when Sun is in the East direction in the morning. Fig. 1 B provides position of tracked panel when Sun is at its highest elevation in the sky at noon and Fig. 1 C provides position of tracked panel when Sun is in the West direction.

In one embodiment, the solar panel which is tracked in the East (Fig. 1A) in the morning, moves through 75° in about 5 hours of time till noon when it is almost parallel to the ground (Fig. IB). When Sun is tracked by the panel in the East, it reaches a minimum limit of vertical position. This position as provided in Fig. 1A in X axis is attained when pump motor from West fluid storage container is turned on and starts transferring fluid to East fluid storage container as a result most of the fluid from West fluid container is transferred to the East fluid storage container making East fluid storage container heavier than West fluid storage container, resulting in shifting of centre of gravity of solar panel down to the East, to the extent where angle of panel is reached to the minimum limit of the vertical position facing East at around Sunrise.

As Sun moves from East to West over a day, East pump motor is turned on as a result most of the fluid from East fluid container is transferred to the West fluid storage container making West fluid storage container heavier than East fluid storage is transferred to the bottom container with the help of pumps. This action is a result of container, resulting in shifting of centre of gravity of solar panel down to the West, to the extent where angle of panel is reached to the Maximum limit of the vertical position facing the first, second or any another direction, West as shown in Fig 1C at around Sunset.

In between, around noon, panel becomes almost parallel to the ground as fluid in both containers is of almost equal weight which keeps centre of gravity almost in the centre. This horizontal position of panel is achieved in X axis as shown in Fig IB at around noon.

At Sunrise, Sun actually rises in North-East direction rather than in East direction. Thus, panel should be tracked in North-East direction. This requires tracking and movement along Y axis in addition to X axis. In order than panel moves along Y axis and in North direction in addition to East, it is necessary that fluid from top container activation of corresponding pump motor which in turn is activated by switching circuit which receives direction from microcontroller.

Around noon, panel becomes almost parallel to the ground as shown in Fig. 1 B. This action is a result of activation of corresponding pump motor is activated by switching circuit upon receiving direction from microcontroller.

In the evening at Sunset which occurs in North West direction rather than West, panel has to be tracked in North West direction as shown in Fig. 1C. Therefore, it is necessary that fluid from top container is transferred to the bottom container with the help of pumps. This action is a result of activation of corresponding pump motor which in turn is activated by switching circuit which receives direction from microcontroller.

It is understood by the person skilled in the art that first, second and third directions are not the only positions taken by solar panel in response to fluid transfer. They are amongst the several tracking positions of the panel throughout the day and these positions may vary depending upon geographic locations. Above positions are true for coordinates 20.1623° N, 74.0300° E.

In the working of tracker, East-West and North- South light-based position sensors measure signal which is a voltage output (SO or S I) and compare it with standard voltage output (along with tolerance window). If the voltage output does not match the standard value, switching circuit is activated upon instruction from microcontroller. This activated switching circuit activating pump motor thereby further causing weight displacement by transfer of fluid and thereby tracking the panel. When sensor reading (voltage output) falls within "standard signal reading (including tolerance window), the pump motors are turned off and along with switched off motors, non-return valves come into action to stop fluid transfer. This instant phenomenon helps to keep panel fixed in a specific tracked position as long as the sensor reading matches the standard signal value.

The terms standard signal, standard signal value and standard signal reading are used synonymously and include tolerance window when not specified. The in-built program runs continuously enabling sensors to take multiple readings within a second and real-time tracking is thus possible.

FIG. 2A is an inner diagrammatic view of a fluid storage container 108 with fluid pump 1016. The pump 1016 is attached to pipe 111. It has a non-return valve 206 fitted in almost vertical position. Fluid storage container design has a small slight opening on top having an air filter to keep solid particles away and to achieve airflow without hindrance while displacement of fluid. When pump is activated, valve is closed due to pressure of fluid and displacement of fluid is possible through pipe 111. When pump is switched off, water pressure on ball of valve is dropped and valve opens up and thereby breaks the continuous fluid flow by inclusion of air and fluid transfer is not possible. Fig. 2 also provides how fluid storage container is hanged from the frame 102 with the hook or any attaching 112.

UV radiations from Sun may make plastic brittle. Therefore, the fluid storage containers can be made of metals and a waterproof coating or paint can be applied on such containers. Alternatively, galvanization or similar processes can be employed to prevent fluid storage containers from rusting or other environmental hazards.

FIG. 2B and FIG. 2C show perspective view of valve in open and in closed positions in an embodiment. In this embodiment, the, left and right fluid storage containers have non-return valves to block the flow of fluid from left to right and right to left fluid storage containers and from top to bottom fluid storage container in an attempt to equalize the level of fluids in fluid storage containers due to gravitational potential energy. Non-return valve normally allows fluid (liquid or gas) to flow through it in only one direction. The non-return valves stop the transfer / displacement of fluid by inclusion of air flow, once the sufficient fluid is transferred to achieve tracking. Whenever tracking is achieved, solar panel is almost perpendicular to the Sun, upon receiving signals from light based position sensors. As shown in Figs. 2A, 2B and 2C, three one way valves are used to prevent the unnecessary gravitational fluid flow. The valve has inner cylindrical pipe 304 and outer cylindrical pipe 305. Inside outer cylindrical pipe 305, a ball 306 is placed and the end of outer pipe 305 is closed by blocking O-ring 307. The diameter of ball 306 is greater than inner cavity of O-ring for the purpose of blocking flow in one way. Preferably, the ball is made up of a non-corrosive material. The inner pipe 304 has slit opening 308 of size less than the diameter of ball 306 for clear flow of physical substance through outer cylindrical pipe 305 in opposite direction. The valves 206 are installed in vertical position at the outlet of top, left, right pump 1011, 1016, 1021 respectively. As shown in FIG. 4 B when associated pump is turned on, due to the pressure exerted by fluid, ball 306 closes the opening of O- ring 307 and fluid flows through pipe/tube normally without any hindrance on to which valve is connected. As shown in FIG. 4 A when pump is turned off the ball 306 opens up the blocking O-ring 307 and breaks the continuous fluid flow by introducing air flow into fluid flow and thus fluid stops flowing to associated fluid storage container.

In this embodiment to keep a simple design, a ball valve is not a spring-loaded ball. The cracking pressure, a minimum upstream pressure at which valve operates, is low for such type of ball valves that are not spring loaded. Hence, to keep cracking pressure low and for proper operation of this type of valve, it should be installed in vertical direction as shown in Fig 2 so that in absence of spring, the ball can come down due to gravity.

Alternatively, for the purpose of weight displacement, instead of one tube, two tubes with a valve on each tube can be used. In this design, one tube goes from first storage container to the other while a second tube goes from the second storage container to first to allow fluid flow from tubes in only one direction. Minimum cracking pressure should be selected to block fluid flow due to gravity.

In yet another embodiment an electrically controlled solenoid valve is used in between single pipe carrying weight displacement fluid. Upon activation of any pump this valve also opens by means of an electric current.

As per the fluid dynamics, fluid in any system always try to stay in equal levels / equalize when allowed to flow. In the present case, even when electric fluid pump is turned off, fluid keeps flowing in the same direction in order to equalize levels. The one-way valves 205, 206 and 207 are used to prevent "the unnecessary fluid flow in an attempt to achieve equalization". Alternative to above fluid displacement system is solid weight displacement system, the solid weight displacement system is one in which solid weight is transferred or any fluid or liquid in any confined container is transferred just like solid.

The solid weight displacement system can be a pump system such as an air pump or it employs solid weight (including liquid in solid container), weight moving mechanism and a bidirectional motor. The bi-directional motor has a gear such as worm gear or planetary gear or geared coupling or direct coupling etc.

The suitable solid weight displacement systems can be used as described below: In one embodiment as described in figure 4A, Scissors weight displacement system / mechanism is adopted as weight displacement system. As shown in 4B, the scissors weight displacement assembly is located on the backside of solar panel and is supported by solar panel support in horizontal and vertical plane. The components of this system include i) weight 1107, ii) roller bearings 1104 that carry the weight iii) specific arrangement of scissor plates forming scissor assembly, iv) horizontal track 1103 provided for smooth weight displacement and to prevent weight from getting out of the track, v) movement channel 1111 which allows the movement of weight in horizontal direction while isolating the vertical movement of scissors mechanism, vi) lead screw arrangement 1115 with lead screw 1114, vii) threaded nut 1113, viii) a one axis hinge 1116 which provides some degree of angular movement to the joint while keeping arm connected and ix) bi-directional motor 1112.

In figure 4B, 1101 represents solar panel and 1102 represents its support. In two dimensional structure 1101 and 1102 may not be much differentiated.

Scissors weight displacement mechanism is operated as follows. The scissors assembly contains specific arrangement of scissors plates in such a way that the attached weight 1107 can be moved at the sides of solar panel 1101 and horizontal track 1103 allows the movement of weight in horizontal direction (from East to West). Roller bearings 1104 carry the weight and 1103 provide horizontal track for smooth weight displacement and prevent weight from getting out of the track. One arm of scissors mechanism is connected via flexible attachment like one axis hinge 1116 to the threaded nut 1113 which is threaded onto the leadscrew 1114 and other arm of scissors mechanism is connected to an outer shell 1117 of lead screw assembly via flexible attachment like one axis hinge 1116. This hinge provides some degree of angular movement to the joint while keeping arm connected. This mechanism works on the principle that when pressure is applied on one side of the scissors mechanism 1108, extension is achieved elongating the crossing pattern as link of scissors assembly will fold out and expand in terms of length from its origin. This extension and elongation or folding out pushes the weight 1107 causing displacement of such weight which further causes shift in the centre of gravity of the solar panel enabling it to tilt.

First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate motor 1112 in specific direction along with the shaft of the motor. The bi-directional motor 1112 controls the direction of scissors arm 1108 through the motion of lead screw. When the lead screw 1114 rotates, the threaded nut 1113 also moves, and thereby arm of the scissor assembly either contracts or expands resulting in weight displacement. For electrical control, an H-bridge driver configuration of switching elements in circuit can be used.

The above design can be adopted for dual axis solar tracker by using two perpendicular scissor plate assemblies wherein one weight is moved along East - West axis and the other weight is moved along North - South axis causing tilting of panel in direction of movement of weights.

Alternatively, scissors weight displacement mechanism which is used in power window mechanism used for automatic window control in car can be used.

Another weight displacement system which is used to tilt solar panel is solid weight displacement system as described in figures 4C-E.

Figure 4 C shows Angular weight displacement system having angular moving arrangement of weight displacement rod or arm. The system has motor 1112 with motor shaft. H-bridge motor driver circuit controls motor. The weight 1300 is connected to weight displacement rod 1305. This rod has lower bearing 1303 and upper bearing 1304. The two bearings are driven onto two tracks viz. lower roller track 1301 and upper roller track 1302 respectively. This arrangement can be also reversed depending upon requirements, such arrangement of roller bearings reduce unnecessary force exerted by weight onto the motor shaft of motor 1112. The motor 1112 has worm gear drive assembly with designed gear ratio to produce lower rpm (preferably in range of 0.1 - 10) and higher torque. The worm gear assembly provides natural lock to the motor shaft when not powered. First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate motor 1112 in specific direction along with the shaft of the motor. This leads to rotation of the weight displacement rod 1305 along with the weight 1300 at desired side of panel in angular manner and thereby weight of system can be displaced for tracking movement of solar panel. To operate any weight displacement system involving bi-directional motor, weight should not travel beyond its defined limit. Rotary encoder is therefore incorporated in such systems. Preferably, it is attached to the shaft of the motor.

In addition to above, two more methods for angular weight displacement are provided under figures 4D and 4E.

Fig. 4D provides another method of angular weight displacement for dual axis tracker where instead of 1301 and 1302 bearing tracks for upper and lower roller respectively, circular roller bearing track 1307 is used.

As provided in Fig. 4D, the weight displacement rod 1305 can have the Z shape / Zigzag shape to reduce unnecessary load of weight onto motor shaft.

Fig. 4E provides lead screw actuator mechanism 1308 for angular displacement of weight. The roller bearing 1303 is connected to weight 1107 through connector 1314. The weight is connected to weight displacement arm 1302. The roller bearing 1303 is guided on track 1301. The lead screw rod 1304 is connected to the motor 1112 through geared or direct coupling. A travelling nut 1306 is threaded onto lead screw rod 1304. The lead screw is fixed to the solar panel by a support bearing 1313 while keeping its angular freedom. A hinge 1305 connects travelling nut 1306 to 1302 weight displacement arm having slotted support 1307. The slotted support 1307 enables weight displacement arm to move in both direction so that weight displacement arm can adjust its length and position in order to complete angular motion of weight 1107 along with roller bearing 1303.

For motor control H-bridge motor driver can be used. First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate motor 1112 in a specific direction along with the shaft of the motor which leads to rotation of the weight displacement rod 1302 along with the weight 1107 at desired side of panel in angular manner and thereby weight of system can be displaced for tracking movement of solar panel. Fig 4F provides use of lead screw actuator mechanism 1309 for linear displacement of weight. A lead screw 1304 is connected to the motor 1112 through geared or direct coupling and fixed to the solar panel by a support bearing 1313. A travelling nut 1306 is threaded onto lead screw rod 1304. A weight 1107 is connected to traveling nut 1306 and has roller bearing 1303 for support. The roller bearing 1303 is guided on track 1301.

First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate motor 1112 in specific direction along with the shaft of the motor. As motor 1112 is set into motion, it moves a lead screw 1304 and lead screw moves the travelling nut 1306. The travelling nut moves the weight. The bearing 1303 supports movement of weight by sliding on track 1301. Movement of weight causes tilting of solar panel in desired direction.

Fig 4G shows use of alternate lead screw actuator mechanism 1311 for linear displacement of weight. A lead screw link rod 1312 is connected to the motor 1112 through geared or direct coupling. Fig. 4G and 4H provide lead screw actuator mechanism for linear displacement of weight in single axis solar tracker.

Fig. 4H provides a multi stage actuator in which two or more linear actuators are connected in series. In one embodiment as described under figure 4H two linear actuators are connected in series. In another embodiment, 5-6 linear actuators are connected in series. The number of actuators may also depend upon the size of solar panel and size of actuators. It is desired that the entire dimension of solar panel from East to West direction shall be covered in this system. The system, on one side has a weight 1107 attached and on the other side there is a motor 1112. By changing direction of motor, weight can be linearly moved towards or away from motor 1112. When weight 1107 moves towards motor, the solar panel tilts in the direction of the motor whereas when the weight travels maximum distance away from the motor, the panel tilts on opposite side of the motor. When weight is at or near the centre of panel, the panel is almost horizontal to the ground.

The components of the system are shown for two actuators that are linked together. They include for the two links of the actuators, outer pipes 1700 and 1800, inner pipes 1701 and 1801, lead screws 1702 and 1802, threaded nuts 1703 and 1803, maximum limit stopper rings 1704 and 1804 and minimum limit stopper rings 1705 and 1805.

First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate motor 1112 in specific direction along with the shaft of the motor. The direction of motor is controlled by Microcontroller or microprocessor upon receiving input signals from Sensors assembly. When microcontroller receives signal from sensor assembly, motor 1112 is set into action i.e. rotational motion in one specific direction depending upon in which direction panel tilt is required. This rotational motion of motor 1112 is transmitted to lead screw 1702 via gearbox 1706. During expansion of linear actuator, the Lead screw 1702 transmits rotational motion to threaded nut 1703. The threaded nut as a result of this motion starts moving forward on lead screw 1702. At one point, it touches maximum limit ring of the first actuator 1704 and fits at it. The inner pipe 1701 and threaded nut of first actuator 1703 and minimum limit ring of second actuator 1805 are already welded together. Thus, the motion is transmitted from threaded nut of the first actuator 1703 through inner pipe 1701 to minimum limit ring of second actuator 1805 and then to lead screw 1802 and threaded nut of second actuator 1803. This continues till last actuator link in series (even though only two links are shown in this figure) and then the said rotational motion is transmitted to weight 1107 which moves depending upon the direction provided by motor 1112 either towards it or away from it. The fig. 41 provides two scenarios, one wherein the weight is maximum away from the motor known as expanded view and other wherein weight is closest to the motor known as contracted view. Weight is linearly moved towards or away from motor as the case be with the help of roller bearings guided on the track.

Alternative to multi stage actuator, hydraulic or pneumatic or mechanical actuator can also be used.

Fig 4J provides use of lead screw actuator mechanisms for dual axis solar tracker for linear displacement of weights 1400 and 1401 respectively. Depending upon the signals from microcontroller weights 1400 and 1401 are moved towards or away from the motor causing tilting of panel. Both the weights are at or near centre of the panel when the solar panel is almost parallel to the ground. The working is similar to that explained in 4G and 4H except that as required in dual axis tracker, both 1402 and 1403 may be active simultaneously. One actuator is shown in fig. 4J only for illustration purpose and many linear actuators can be applied in series as explained in single axis tracker.

Further, Trammel of Archimedes weight displacement system is employed as solid weight displacement system. The figs. 4K and 4L describe such system for dual axis tracker. The same system can be adopted for single axis tracker. The system has following components i) two weights 1402 and 1403 ii) two channels or rails 1400 and 1401 for two weights to travel / slide iii) rod 1404 which is attached to two weights 1402 and 1403 by pivots, iv) high torque geared Motor 1405 which is coupled to the rod 1404, v) support 1406 attaches motor to solar panel providing freedom of angular movement.

First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate high torque geared Motor 1405 in specific direction along with the shaft of the motor. As the motor moves, its motion causes rod to move. As the rod moves, both the weights attached to the rod move / slide on the tracks provided. This movement of weights causes tilting of panel in the direction where weights travel on their tracks. This system can be implemented for single or dual axis solar tracker. The above mechanism works similar to Trammel of Archimedes. The motor is attached to the centre of rod and the rod is attached to the weights in such a way that when motor is energized, the rod starts moving and while moving it offers angular freedom to the weights enabling the system to move in a path/pattern similar to Sun path.

Yet another weight displacement system is pulley displacement. In an embodiment as shown in Fig 4M, a type of pulley weight displacement system is shown comprising following components i) pulley chain 1503 ii) sprocket gears 1505 and 1506 iii) solid weight 1107 and iv) bidirectional motor connected to sprocket gear 1506. Fig. 4M particularly represents pulley weight displacement system for single axis solar tracker. However, two such arrangements are made perpendicular to each other for double axis solar panel.

In the pulley chain displacement system as provided in Fig. 4M, a pulley chain 1503 is attached at one end to one end of solar panel (in East or West direction) and at the other end to other end of the solar panel (in East or West direction). The pulley chain in between the two ends passes over three gears as shown. The three gears are sprocket gears (toothed gears) engaging the chain when the chain moves in any direction. The gears engage the chain tightly. The bottom gear is connected to bidirectional motor. First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate motor in specific direction along with the shaft of the motor.

As the motor moves, its motion causes bottom gear to move. As bottom gear moves, the chain moves from left to right or right to left based on movement of gear and movement of the motor. The solid weight is connected to one or more such pulley displacement systems. In fig. 4M, weight 1107 is connected to two such pulley displacements systems. As the gears and the pulley chain moves, weight is transferred from left to right or right to left causing tilting of the solar panel. To assure contact of chain with sprocket gear, a chain guide may also be used. The design of 4M is provided only for the illustration purpose and does not limit the invention in any specific way. Alternatives of the components can be used for example, as an alternative to chain, a belt rope or wire also can be used. The Fig. 4M provides an optional component 1504 which represents a braking braking system as described in Fig, 3C.

In yet another embodiment, Roller weight displacement system is used.

Fig 4N Shows one such embodiment having Roller Weight displacement system. The system comprises following components, i) Two rollers 1600 and 1601 as roller a and roller b, ii) roller holders 1603 which attaches rollers to solar panel 1107, iii) weighted sheet 1602 having significant amount of weight which is moved to either roller a or b and rolls over one such roller, wrapping such roller and increasing its weight significantly, iv) two motors 1604 and 1605 as Motor A and B which are attached to the roller at the centre of the roller in concentric manner.

First, signal is received by sensor assembly which is then transmitted to microcontroller which processes the signal and instructs motor driver to rotate motor in specific direction along with the shaft of the motor. When the motor moves, it moves the rollers in one direction. As rollers move, weighted sheet moves towards one of the rollers and wraps it increasing its weight. As a result of this increase in weight of the roller, the panel tilts in the direction of such roller.

To drive the motors in bidirectional manner preferably an H- Bridge configuration of switching circuit is preferred, same H-Bridge circuit control both motors.

As provided in above various weight displacement systems wherein few systems are provided with bearing whereas others with channel for smooth displacement of weight. However, it is understood that any system with roller bearing may have weight displacement channels instead of such bearings and any system with channels may have bearing in place of such channels. Also, any system functionally playing same or similar role to that of roll bearings or channel can be substituted and inventors do not wish to limit invention in any way to any particular system.

Hinge, Counterbalance Mechanism and braking system.

Fig. 3 A provides perspective view of a double hinge joint 300. The double hinge joint 300 has two base plates (303) at which the hinge is attached to central supporting pole at lower end and to frame at upper end. A hinge 301 has degree of freedom to rotate in X-axis at 160 degrees and hinge 302 has degree of freedom to rotate in Y-axis at 160 degrees. Hinges are well lubricated with lubricant for longer operational life. Alternately any other mechanism can be used to support free movement of panel along X and Y axis and any such mechanism is considered as part of the invention.

FIG. 3B shows perspective view of counterbalance extension spring connected to central supporting pole 103 and supporting frame 102 through counter balance connector rod 104. The spring is connected to the solar frame at some angle around 30-40°. In a preferred embodiment, the angle is set at around 35° as an average of i) angle which earth makes to its orbit of revolution around 23.44° and ii) the difference between the highest position the Sun reaches on the summer solstice and on the Winter solstice North or South of the tropics is double the tilt, or 46.88 degrees as shown under fig. 9. Alternatively, any suitable angle can be chosen. The counterbalance extension spring, connector and angle of connector with the solar frame provide motion of solar panel naturally in a Sun path, which reduces the on time of pumps as Sun moves through its path. Alternatively, other such mechanisms can be used.

The terms counterbalance extension spring and counterbalance spring are used synonymously.

The spring is at a position opposite to top fluid storage container. The fluid displacement between top and bottom fluid storage container helps Solar panel in tracking Sun in North-South direction and the fluid displacement between left and right fluid storage container helps Solar panel in tracking Sun in East- West direction. When solar panel starts moving, tension is set in counter balance spring which is stretched and in trying to come to its original natural compressed position, it retracts and helps solar panel from going in any extreme East -West or North- south direction and provides controlled movement of panel purely driven due to signals from the light dependent sensors.

Alternatively, in solid weight displacement systems, the spring is at a position opposite to solid weight.

One of the most important criteria of selecting a spring, is a spring constant which is a measure of resistance to expansion or contraction of spring. In other words, stiffness of spring is important and range is provided herein to give some directions for the users. The spring constant should be preferably between 3 - 8, most preferably between 4-6 lbs/in. The spring constant may vary depending upon parameters like weight of solar panel, frame, weight of fluid's etc. It helps to stabilize solar panel all the time.

In an embodiment, a spring of spring constant of 5.8329 lbs/in is used. In the same embodiment, length of connector rod 104 is 16 inches. This embodiment is tested at wind speed of 7 m/s and has provided successful operation. Based on local wind speeds spring with suitable spring constant can be used. Hence without restricting to a particular value, a preferred spring constant value is provided. It is preferred to install such dual axis solar tracker with spring mechanism facing towards north direction to allow natural movement of panel in a Sun path.

Motion / Wind sensors and brake system / braking system

Additionally a wind sensor such as anemometer can be added in sensor panel assembly 501 to stop the tracking operation and to put tracker to rest in stable position (parallel to ground) during heavy winds tornado, cyclones etc.

Alternative to anemometer, a condenser microphone is employed as a wind sensor. As an alternative to wind sensor or as an addition to wind sensor, motion sensor can be added in sensor panel assembly 501. Motion sensor such as EVIU (Integrated Motion Unit) is a combination of gyroscope, accelerometer, multi-DOF motion sensors and magnetometer etc. and it provides accurate motion readings in any scenario.

Motion Sensor Data can be filtered out with digital or analog filters to acquire noise free motion data.

When wind sensor / motion sensor detects wind speed / motion of panel beyond threshold limit, microcontroller acknowledge this as a signal to temporarily stop tracking movements and further it activates braking system. When conditions resume to normalcy, braking system is deactivated and the tracking operation begins. To prevent accidental triggering of wind sensor or motion sensor, a particular delay is set in system is such a way that a high intensity wind or motion when lasts only momentarily, such signals are not recognized by microcontroller to take any further actions.

For complete protection of solar tracker system against extreme winds, cyclone, tornadoes, a braking system is implemented to prevent any unexpected damage to solar tracker system.

Brake or braking system is an optional but desired feature of the solar trackers enumerated in the present invention. It is optional because it is not required for functioning of solar trackers. It is desired because in conditions where the location is highly windy or where solar panel is likely to experience jerks, its incorporation helps to stabilize trackers.

Brake system can take input signal from motion sensors such as angular sensors or wind sensors. Thus, brake system comes into action if it receives such signals to stop trackers due to excessive movement of panel or merely when wind sensors sense a high velocity of winds. High velocity of winds can be for example greater than 40 m/s.

In an embodiment, braking system is inertial braking unit (commonly used in car seat belts retractor mechanism).

In one more embodiment, braking system is chain braking system.

In yet another embodiment, braking system is gear braking system.

In one embodiment, such inertial braking unit is attached in between central pole or supporting pole and solar frame or attached to central pole, counter balance connector rod and solar frame.

When speed of wind exceeds braking velocity (a pre-defined parameter), an inertial braking unit instantly applies brake to stop any swift movement of solar panels.

When the external wind force is stopped, inertial brake is automatically recovered and brake is released therefore solar tracker system can work normally.

One of the most important feature of inertial braking unit is that it works automatically and instantly and does not require any external control. Another braking system is chain or gear braking system. Such systems are shown in Fig. 3C and 3D. As shown in Fig. 3C, the components of chain braking system comprises are i) brake actuator 1501, ii) locking hole plate 1500, iii) a metallic rod 1502, iv) chain 1503 which is engaged over sprocket (toothed) gear 1505.

When input from motion sensor or wind sensor or both the sensors indicates that there is excessive wind or excessive panel movement that can destabilize tracking system, brake actuator propels from within a metallic rod 1502 which passes through the chain and locking hole plate locking the entire system and thereby preventing motion of the solar panel. Alternatively, as shown in Fig. 3D, the brake actuator propels the metallic rod from within through sprocket gear and locks it thereby preventing motion of the solar panel. When normalcy (normal weather condition) resumes, metallic rod 1502 is removed from hole plate 1500 and chain 1503 or from sprocket gear unlocking the entire system making it ready for the movement and thereby tracking.

It is understood that the braking systems described herein do not limit the scope of the invention and any suitable braking system can be employed.

Brake actuator 1501 and locking hole plate 1500 are mounted onto the supporting pole of the solar panel 103. Both the ends of chain 1503 are attached to the right and left edges of solar panel frame (East and West direction). The sprocket gear 1505 is mounted on the supporting pole and have freedom of circular motion. The chain 1503 is always in contact with the sprocket gear to avoid disengagement. To assure contact of chain with sprocket gear, a chain guide may also be used.

Switching Circuit Elements

FIG. 5A is a solar tracker circuit diagram or solar tracker electrical switching circuit diagram having 4 switching components. In a preferred embodiment, switching component is relay. Thus, there are 4 relay components viz. RLY1, RLY2, RLY3 and RLY4. Alternatively, instead of relay, solid state switching device can be used as a switching component. To trigger relay, based on logic level signals of microcontroller, each relay is connected to Bipolar junction transistor. In place of bipolar junction transistor, any type of transistor can be used. One preferred transistor is an NPN transistor. Alternatively, opto-transistor can be used. A bipolar junction transistor such as NPN transistor receives Microcontroller Digital Logic signal. There are two levels of signals that go from microcontroller to bipolar junction transistor as follows:

a) Logic high or logic 1 - This type of signal is given when tracking is required i.e. when there is a need to move solar panel to track Sun. Upon receiving this signal from microcontroller, it is forwarded by NPN transistor to relay and pump motor is activated to cause transfer of fluid to cause panel movement.

b) Logic low or logic 0 - This type of signal is given when tracking is not required i.e. when there is no need to move solar panel to track Sun. Upon receiving this signal from microcontroller, it is forwarded by NPN transistor to relay and pump motor is deactivated to stop transfer of fluid and panel is tracked.

In this embodiment, microcontroller is supplied with AC to DC switch mode power supply. The arrangement of AC to DC switch mode power supply, Electrical switching circuit, Microcontroller and pump protection circuit is in a rectangular box (not shown in figures)

AC Voltage source 1002 is used to power AC Pump Motors and AC to DC Switching Power Supply is used to provide DC power 1001 to microcontroller and sensors assembly.

FIG. 5A provides connection between microcontroller's logic signals 1008, 1013, 1018 and 1023 with electrical switching circuits. Motor Protection element such as varistor 1006, 1012,1017,1022 are connected in parallel to the motor, Voltage source 1001 provides DC power to the circuit and 1007 is DC Ground. The connectivity is as follows:

i) NPN- 1003 transistor (or any electrical switching component) receives microcontroller logic signal 1008 and it (NPN- 1003) is connected to RLY1, ii) NPN- 1009 transistor (or any electrical switching component) receives microcontroller logic signal 1013 and it is connected to RLY-2

iii) NPN- 1014 transistor (or any electrical switching component) receives microcontroller logic signal 1018 and it is connected to RLY-3 iv) NPN-1019 transistor (or any electrical switching component) receives microcontroller logic signal 1023 and it is connected to RLY-4

The sequence of receiving signal is as provided in Fig. 6.

The pump movement takes place as below.

When a particular NPN transistor (or any electrical switching component) receives logic signal from microcontroller, it switches on the corresponding relay (switching component) which passes required AC power 1002 to the associated pump motor and pump motors is activated. The pump motor which is activated throws or transfers fluid from the container having such pump to the other container with which it is connected through tube or pipe. For example, when Sun is in the East, panel needs to be moved to East from West direction. In this case, logic signal of microcontroller 1023 is received by NPN-transistor 1019 and it switches on RLY 4, and pump motor 1021 is activated to cause transfer of fluid from West fluid storage container to East fluid storage container. The East fluid storage container becomes heavier than West container as a result of which centre of gravity of solar panel frame is shifted tilting the solar panel in East direction.

Once the desired position by the panel is achieved, microcontroller receives around standard signal reading viz. from 2.2 -2.6 in this embodiment, from light based position sensors (or any similar sensor). Once standard signal reading (viz. around 2.5 v in this embodiment) is received by Microcontroller it sends "Logic zero" Signal to NPN transistor (or any other transistor) as per the built-in program. As a result, relay circuit (switching circuit) disconnect pump motor from ac voltage source 1002, thus pump motor is turned off. Since the pump motor is inductive type of a load, it produces back EMF (Electromotive force) across its terminals during switching off period. When the voltage increases beyond threshold voltage, a varistor which is connected in parallel dissipates the energy of inductive spike and thereby protect windings of motor.

In the overall working of the solar tracking apparatus as described herein it is understood by person skilled in the art that at the most one or two pump motors are active at a time. For example, if solar panel is to be turned from East to West, fluid transfer should be done from fluid storage container 108 to 109 and accordingly pump 1016 in fluid storage container 108 should be activated. In this situation, microcontroller has already received signals from LDR and it sends the Logic High signal to relay circuit (switching circuit) RLY3 and not others. However, at the same time the tracking in North-South direction is simultaneously required, either of RLY 1 or RLY2 are also activated by the microcontroller depending upon whether tracking is required in North or South.

It is understood by person skilled in art that there are various methods to create an electronic switching circuit by using various components, although they all achieve same results of controlling motors.

Figs. 5B-5E describe various types of light Sensitive Elements that can be incorporated in the solar tracking apparatus as either a voltage divider sensor or in anti- series configuration in accordance with the present invention for tracking position of Sun.

Fig. 5B provides standard resistive voltage divider configuration.

Fig. 5C provides LDR' s in voltage divider sensor. As an alternative to LDR, CMOS (complementary metal oxide semiconductor) image sensor can be also used.

Fig. 5D provides photodiodes in voltage divider sensor.

Fig. 5E provides solar cells in anti-series configuration

It is preferred to install an opaque slit in between light sensitive elements of X axis sensor and Y axis sensor to improve sensor performance. It is further preferred to install light sensitive elements at 45° as it is will cover more than 180° field of view and thus it will sense light from very wide angles.

A simple example of a voltage divider is two resistors (light sensitive elements) connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them. A phototransistor (Not Shown in figures) can also be used as light sensitive element. Weatherproof enclosure /coating to the circuit is helpful for reliability. Alternatively, a dome of diffused or undiffused glass or of UV resistant material can be used to enclose the sensor board to reduce damage to electronic circuit and components against ultraviolet rays. X and Y axis light based position sensor, lux sensor and angular position sensor are mounted on a sensors panel assembly 501 for dual axis solar tracker and 806 for single axis solar tracker as shown in Fig 1 and Fig 8 respectively.

The sensor signal is the most important parameter which determines the movement of solar panel so that panel can track the Sun. The light-based position sensor and angular position sensor of Sun, and are physically attached to the moving solar panel facing upward direction so that the sensors assembly move along with the solar panel while tracking.

In this embodiment, each sensor except 5E is supplied with 5v DC power supply. Thus, 5v is input voltage for sensor. Based on angular position of panel with respect to Sun, output voltage (SO or S I) changes based on light intensity falling upon two light sensitive elements connected in voltage divider configuration and it is determined as follows.

According to Ohm's law, the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship where I is the current, Vi is voltage input and R is resistance.

Vi = I x R, so I = Vi / R

In the present case Resistance is in the form of combination of resistor Rl and R2 wherein Rl is a resistor towards DC supply and R2 is a resistor towards ground, hence this equation is as follows:

Vi = I x (R1+R2), so I = Vi / (Rl + R2)

Since output voltage is measured from the connection between the two resistors Rl and R2 where R2 is the resistor towards ground, output voltage Vo or SO or S 1 is as follows:

Vo or SO or S 1 = I x R2 and therefore, I = Vo / R2

Equating both I, we get Vi/ (Rl + R2) = Vo/R2 or

Vo or SO or S I = Vi x R2/ (Rl + R2)

Thus, the output voltage (Vo) which is a sensor signal SO or S 1 is defined by the following equation SO or S I = Vi x R2/ (Rl + R2)

This equation is true for all resistive light sensitive elements connected in voltage divider configuration.

In one embodiment, when Sun is to the East or North and

Rl =lkQ, R2=10 kQ, Vi =5v, then, SO or S I = Vi x 10 / (11) = 5 x 10/11 = 4.5454

In another embodiment, when Sun is to the West or South, and

Rl =10 kQ, R2=l kQ, Vi =5v, then, SO or S I = Vi x (1/ (10+1)) = 5 / 11 = 0.4545.

The Sun will be considered tracked when output voltage SO or S 1 becomes equal to "input voltage (5v) supplied across 2 resistors" = 2.5 v (+ tolerance window). Thus, when Rl = R2, SO or S 1 = 5 x R2 / 2R2 = 5/2 = 2.5 v. The output voltage or

SO or S I has been given a tolerance window of 2°-3° degrees. In an embodiment,

SO can be from 2.2 - 2.6 in ideal condition in which the Sun is tracked by the panel.

If SO or S 1 does not fall between 2.2 - 2.6, tracking mechanism is triggered.

The Fig 5E Shows two photovoltaic cells (solar cells) connected in anti-series configuration, alternatively any photovoltaic element (elements that produce voltage upon incident light exposure) can be used in anti-series configuration. In such setup, voltage across first element is Rl, Voltage across second element is R2, and output voltage SO or S 1 is given by

SO or S I = R1 - R2.

Connecting a fairly high value resistance (like 10kQ) in parallel to each photovoltaic element will improve the sensor performance, also it is possible to connect photovoltaic elements in series connection output voltage for series connection will be given by SO or S 1 = Rl + R2.

FIG. 6 is a block diagram of circuits used in a single or dual axis solar tracking apparatus, this diagram explains relationship and connectivity between

1) Microcontroller or microprocessor

2) Sensor assembly having sensor panel fitted with i) at least four light dependent resistors (two for East-West direction and other two for North-South direction), ii) motion (angular) position sensor, and iii) lux sensor,

3) motor driver (4 channel relay circuit or a switching circuit), and

4) motor protection (pump motor protection or bi-directional motor protection) A circuit 500 begins with AC electrical power 600 to be taken from the available grid power supply. This circuit works on any of AC or DC power supply. Through an AC to DC Converting Switch Mode Power Supply 601, it provides 5 volts DC supply voltage or any other required DC Voltage to microcontroller 602. Depending on type of motor AC / DC, power supply is made to motor driver directly from the power source or after AC to DC switching as shown by 607. The sensors 603 are interfaced to the microcontroller 602 for light based position tracking of Sun and angular position measurement of attached solar panel. The microcontroller 602 sends output logic signal to control 4 channel relay circuit (Motor Driver circuit) 604. The 4 channel relay circuit (Motor Driver Circuit) 604 is directly connected to AC voltage source 600 or Dc voltage source from 601 . The 4-channel relay circuit (Electrical switching circuit) 604 uses logic signal from microcontroller 602 to switch power from either AC Voltage 600 or DC voltage source from 601 through 607 to pump motor 606 through Motor protection circuit 605. Nature of the power supply is selected according to AC or DC Type of Motor is Used. The pump motor protection circuit uses varistors to suppress the back emf produced by the pump motor during switching off period of pump motors 606. Alternative to the varistor diode can be also used .

It is necessary that all sensors in sensor assembly provide accurate reading. Hence it is essential to use calibration rig for calibration of various sensors. Such a calibration rig consists of a perpendicularly attached light sources with calibrated lux value projecting on LDR's and according to difference of calibrated values and real-time values from sensor, an error factor is calculated and added via programme into each sensor board for proper calibration.

Similarly motion sensor can be calibrated by mounting / placing sensor board parallel to the ground surface as a reference. Further error values are corrected with the help of reference values.

Method of using Solar tracker in accordance with the present invention viz. operation of Solar tracking apparatus presented in Figures 7A and 7B is as below. Fig. 7A and Fig 7B are flowcharts of the process of repositioning the solar panel according to Sun's position in the sky. Fig. 7 A and 7 B provide repositioning of solar panel along X axis i.e. in East - West and Y axis i.e. North-South direction. In an ideal condition when LDR sensors attached to the solar panel is parallel to the Sun tracking both azimuth and altitude, LDR sensor on X axis and Y axis will return half (SO or S I = 2.5v) of the supplied input voltage (Vi=5v). Thus, if 2.5 v signal (SO or S I) is obtained, it is considered that the solar panel is tracked.

The LDR signal values at different positions of Sun along X axis are as follows: When Sun is in the extreme East and panel is towards West of Sun = 5v

When Sun is in the extreme West and panel is towards East of Sun = Ov

When Sun is tracked = 2.5v,

However, in practical conditions where wind and other environmental factors play a role, slight deviations from ideal voltage output (Vo) / signal (SO or S 1) is obvious. Thus, we need to provide some tolerance window such as 2°-3° tolerance window to the 2.5, thus tracking window is defined with this tolerance window.

Thus, when Sun is to the East of solar panel, value of SO is > 2.6 but < 5 and when Sun is to the West of solar panel, value of SO is < 2.2 but > 0.

In the preferred embodiment, the light-based position sensor value (SO) when panel is tracked varies in between 2.2-2.6. This tolerance window will not affect the accuracy of tracking Sun azimuth and altitude negatively. This tolerance window is one of the important factor determining accuracy and frequency of tracking. If this window is small, it increases frequency of tracking and if it is large it will decrease frequency of tracking.

If X axis light based position sensor value (SO) is less than 2.5 (in this embodiment, less than 2.2) it indicates that Sun is to the West side and solar panel faces towards East side. The East pump motor is activated to transfer fluid from East storage container to West storage container so that panel starts moving towards West side. This condition is provided in steps 705-706 of Fig. 7A. Alternatively, in solid weight displacement systems employing bi-directional motors, the motor is activated in such a direction that weight moves towards West direction tilting panel towards West. If X axis light based position sensor value (SO) is more than 2.5 (in this embodiment, more than 2.6) therefore Sun is to the East side and solar panel faces toward West side. The West pump motor is activated to transfer fluid from West to East so that panel starts moving towards East side. This condition is provided in steps 707-708 of Fig. 7A. Alternatively, in solid weight displacement systems employing bi-directional motors, the motor is activated in such a direction that weight moves towards East direction tilting panel towards East. Thus accordingly, in 706 and 708, either pump motor activation or bi-directional motor activation to produce movement of fluid or solid respectively is provided to cause movement of solar panel.

When signal value (SO) is within tracking window of 2.5, for example, between 2.2- 2.6 as in the preferred embodiment, solar panel is tracked hence both the pump motors are switched off and no transfer of fluid takes place either from East to West or from West to East. This is provided in steps 703, 704 and 709. Alternatively, in solid weight displacement systems employing bi-directional motors, the motor is switched off and no movement of solid weight takes place in any direction.

The terms East pump motor and left pump motor, West pump motor and right pump motor are used synonymously.

Fig. 7B provides tracking of Sun along Y axis i.e. in North - South direction as follows.

Light based position sensor value at different positions of Y axis (ideal values are given)

When Sun is to the extreme North = 5v

When Sun is to the extreme South= Ov

When Sun is tracked = 2.5v (2.2v - 2.6v as explained before)

Thus, when Sun is to the North of solar panel, value of S 1 is > 2.6 but < 5 and when

Sun is to the South of solar panel, value of SI is < 2.2 but > 0.

If the light-based position sensor value (S I) is less than 2.5 (in this embodiment, less than 2.2) Sun is in the South direction and solar panel faces towards North side. The bottom pump motor is activated to transfer fluid from Bottom container to Top container so that panel starts moving towards South. This condition is provided in steps 712-713 of Fig. 7B. Alternatively, in solid weight displacement systems employing bi-directional motors wherein such solid weight displacement systems are used for dual axis trackers i.e. to move panel in East - West as well as in North- South directions, the North-South bi-directional motor is activated in such a direction that weight moves towards South direction tilting panel towards South. If the signal value (S I) is more than 2.5 (in this embodiment, more than 2.6) Sun is to the North and solar panel faces towards South Side. The South pump motor (pump from top fluid storage container) is activated to transfer fluid from top container to bottom container so that panel is tilted to the North. This condition is provided in steps 714-715 of Fig. 7B. Alternatively, in solid weight displacement systems employing bi-directional motors wherein such solid weight displacement systems are used for dual axis trackers i.e. to move panel in East - West as well as in North-South directions, the North-South bi-directional motor is activated in such a direction that weight moves towards North direction tilting panel towards North. When signal value (SO) is within tracking window of 2.5, for example, between 2.2- 2.6 as in the preferred embodiment, solar panel is tracked hence both the pump motors are switched off and no transfer of fluid takes place either from North to South or from South to North. This is provided in steps 712, 713, 716 and 717. Alternatively, in solid weight displacement systems employing bi-directional motors, the motor is switched off and no movement of solid weight takes place in any direction.

When signal value (S 1) is within tracking window of 2.5, for example, between 2.2- 2.6 as in the preferred embodiment, solar panel is tracked hence both the pump motors are switched off and no transfer of fluid takes place either from Top to Bottom or from Bottom to Top. This is provided in steps 710-711 of Fig. 7B.

The terms South pump motor and top pump motor, North pump motor and bottom pump motor are used synonymously.

Operation of Angular position sensors and Lux sensor are as follows:

Parameters for the angular positions are as follows:

Tilt angle is the angle of solar panel with X or Y axis.

XangleMin parameter is minimum tilt angle for X axis (East side), XangleMax parameter is maximum tilt angle X axis (West Side),

YangleMin parameter is minimum tilt angle for Y axis (South Side),

YangleMax parameter is maximum tilt angle for Y axis (North Side),

Wakeup parameter is minimum light intensity value to activate solar tracker. In a preferred embodiment, it is set at 12,000 lux. In this embodiment, the tracking system is in inactive mode unless Wakeup value is at least 12,000 lux.

In a preferred embodiment, the further parameters have following values

XangleMin = 10° (tilt angle) and XangleMax = 170° (tilt angle),

YangleMin = 40°(tilt angle) and YangleMax = 110° (tilt angle)

Wakeup = 12,000 Lux.

Tmin = 2.2 and Tmax =2.6 (Tracking Window)

Above values are set so that panel can track at any possible point in Sun path 10°- 170° in X axis and 40°- 110° in Y axis.

Based on location where tracking is required, tilt angles and wakeup value setting may change and hence these values should not be construed as limiting invention in any way.

When the solar tracker operation is initiated at step 700. In step 701, along with Tmin and Tmax, further predefined parameters such as XangleMin, XangleMax, YangleMin and YangleMax are fetched. These limits of tilt angles are set such that the panel is able to track all positions of Sun all day long considering the maximum rotation of solar panel due to double hinge. In step 702 values of sensor parameters SO i.e East-West LDR sensor, S 1 i.e North-South LDR Sensor , XAngle i.e Motion Sensor reading for X axis and YAngle i.e Motion sensor reading for Y Axis are assigned to the respective variables.

In an embodiment when SO and SI values are within Tmin (2.2) to Tmax (2.6) this is a tracked position; no movement of panel will take place.

In another embodiment when When SO and S I are less than Tmin (2.2), the Sun is in West and South and panel needs to be moved to West and South. The East and North pumps should be activated for fluid transfer from East to West and North to South. As long as Xangle is less than XangleMax(170°) and Yangle is less than YangleMax(110°), solar panel keeps rotating on both axis till SO and S I reaches in between tolerance window 2.2 - 2.6.

In yet another embodiment, when SO or S I are more than Tmax (2.6), the Sun is in North East and panel needs to be moved to North East. The West and bottom pumps should be activated for fluid transfer from West to East and bottom to top. As long as Xangle is greater than XangleMin(10°) and Yangle is greater than YangleMin(40°), solar panel keeps rotating on both axis till SO and S I reaches in between tolerance window 2.2 - 2.6.

While moving to the tracking direction if Sun is at Sunrise position or Sunset position i.e extreme East or extreme West, the solar panel rotation will stop at minimum angle XangleMin(10°) or maximum angle XangleMax(170°). If the solar panel is tilted unnaturally / manually / forcefully it will regain the tracking position as soon as the applied external force is removed. Figure 7A and 7B provide one of the possible algorithm to operate the solar tracker. Algorithm can be also implemented in various ways, methods shown here do not limit the scope of the invention.

FIG. 8 is a diagrammatic view of single axis solar tracker which works on the same principle of fluid weight displacement to track solar panel 101 perpendicular to the Sun (not shown in figure). A support 801 holds solar panel frame via two hinges. Unlike dual axis, single axis solar tracker has only two fluid storage containers, a left (in East direction) and a right (in West Direction) fluid storage containers. Left container 803 and right container 808 are hanged on to their corresponding sides, left (East direction) and right (West direction) respectively. A fluid pipe 807 carries fluid either from left to right or in reverse direction. Both the fluid storage containers have fluid pumps fitted with a non-return valve. Fluid pump and nonreturn valve work in a same manner as described under dual axis solar tracker. A counterweight 804 provides stability in motion as well as stability from external forces. Alternatively, spring mechanism can be also used to provide stability to the system.

A light-based position sensor 806 provides real-time location of Sun and sends signal to microcontroller. Microcontroller output signal i.e. logic signals are of two levels "0" and "1". It sends Logic signal "0" when panel is tracked and logic signal "1" whenever repositioning of panel is required.

Based on the signal value SO and its comparison with standard signal value (including a tolerance window), it is assessed whether the panel needs to be shifted to East or West direction (along X axis). Accordingly, electrical switching circuit, activating corresponding pump motor as described in detail under working of dual axis tracker. Activation of pump causes fluid transfer from one fluid storage container to the other. The container which receives fluid, becomes heavy and shifts centre of gravity of the solar panel causing it to move in tracking position. Rectangular box 805 consist of Switch Mode power supply, Electrical switching circuit, Microcontroller and pump protection circuit.

All sensors along X axis are provided in the same manner as provided in dual axis tracker with the only difference that the sensors along Y axis are either not available or do not send data to Microcontroller as there is no provision to track solar panel along Y axis i.e in North - South direction. However according to location fixed average tilt on Y axis is provided for maximum utilization of single axis tracker. FIG. 9 shows a diagrammatic view of selected motion tracks of the Sun 1100 throughout the year from a latitude of approximately 23.44 degrees North, i.e., just on the Northern edge of the tropical zone, there are three different Sun tracks in a polar-type coordinate system. A summer solstice Sun track 1105 is shown with Sunrise and Sunset both occurring North of due East and due West, respectively. A winter solstice Sun track 1110 is shown with Sunrise and Sunset both occurring South of due East and due West, respectively. Finally, the spring and fall equinox Sun tracks 1115 (taken to be the same for illustration purposes) are shown with a Sunrise being due East and a Sunset being due West on those days. As one can see from FIG.9, the Sun takes a different path through the sky depending on the time of year. The exact path also depends on the latitude.

It is appreciated by the person skilled in the art that values for various parameters provided herein are merely for the purpose of understanding invention and do not limit scope of the invention. For example, instead of 5 v DC power supply which is supplied to microcontroller, any other supply such as 3 v or 3.3 v can also be supplied. In those cases, voltage divider will divide corresponding power supply to 1.5 - 1.7 v and tolerance window will be with respect to 1.5 - 1.7.

Similarly based on location such as hilly or mountainous location and availability of Sunlight, tilt angles as well as wake up value of 12,000 lux may change to lower or higher value.

Based on location, such as hilly or mountainous location, even the tilt angle of panel will vary.

Alternative to the Microcontroller, it is possible to use gate array (FPGA), logic gates, PLC (Programmable logic controller), DSP (Digital signal processor), IC (integrated circuits), ASIC(Application specific integrated circuit), discrete components, or any other processing element which will processes input signal according to certain logic and provide output.

For switching circuit different switching elements can be used to serve same purpose of controlling pump motor.

Similarly, the person skilled in the art would understand that any suitable Semiconductor switching device or Electromechanical switching device along with its any subtypes can be added in the present invention as a switching component. The terms switching component and Switching element are used synonymously. Regardless of the above factors, use of this method will give better accuracy of tracking the Sun in both azimuth and altitude.

Solar panel used herein have around 18 % efficiency. They weighed around 25 - 30 kg and solar frame weighed around 8 - 12 kg. Other solar panels having different technology or structure can also be used.

The solar tracker system according to the present invention can be fabricated from number of small attachable parts, for easy and compact transport of the system .while installation set of nut bolts may be used to attach every part or any other techniques such as threading, latching, etc. can be integrated in the parts to reduce number of parts. In a city around Mumbai, single axis and dual axis solar trackers made in accordance with the present invention is used to track Sun and to measure power (Watt) at a particular time in a day as well as to measure cumulative energy (cumulative effort of power acting over time) over a day and compared with the fixed array tracker. Following results are obtained for 300 Watt rated solar panel along with grid tied inverter. This measurement is taken with calibrated AC clamp meter and voltmeter.

Modifications and Scalability of this invention

1. Current system is based on AC Voltage source, with few minor changes in system it can be made operable on DC voltage supply and such systems are part of inventions.

2. Multiple panels tracking: The solar tracking system according to the present invention can be used to track multiple solar panels by scaling the size and strength of associated mechanism.

3. Integration of IOT (Internet of things): Control and monitoring of solar tracking system over the web wirelessly is also undertaken. Levels of weight (for pourable solids such as sand or gravel as solid or fluid such as water or oil etc.) can be monitored with the help of IOT.

The solar tracker system according to the present invention can be connected to the internet/cloud for measurement/monitoring of solar energy being produced, or setting alarms such warning alarms and thereafter for stopping the tracking operation. Warning alarms can take data from various sources such as i) data from wind / motion sensors or ii) weather data from surrounding region or iii) weather data of that region from any web source etc. ahead of the time. Thus, for example, the system will check when extreme levels of wind speed are detected in surrounding region based on the weather data acquired from internet or in another condition, the system can take data of forecasted weather condition of its region ahead of time. In such situations, system can take corrective actions to stop tracking and protect tracking system. This will reduce the any damage to the solar apparatus and provide sufficient time to lock down the system using brakes or other mechanism or avoid tracking in extreme conditions. A dome like structure may be used to cover entire system and to redirect the wind currents away from the system for safety.

The solar tracker system of the present invention may also have a display unit to display real time information such as wind speed as well as other relevant information such as solar energy generated over specific time periods such as last 24 hrs, last week, last month etc.