CLIAMS:W E CLAIM:
1) A floating tank type solar tracking system, the system comprising:
at least two tanks (T1 and T2) connected to each other using a first pipe and a second pipe and a pump for transferring fluid from tank (T2) to tank (T1) through the said first pipe, and a solenoid valve mounted on the said second pipe for transferring the fluid back from tank (T1) to tank (T2); a floating fiber tank (170) that floats in the tank (T1) and moves up and down during solar tracking based on the amount of liquid filled in the tank (T1); supporting rods (160) with their one end mounted on the said floating fiber tank (170) and a cable hook (240) mounted on the other end of the supporting rods (160);
a cylindrical rod (130) mounted on the tank (T1) and a having fiber cylinder (60) with a ball joint (50) mounted on the cylindrical rod (130) wherein the fiber cylinder (60) having a rack and pinion arrangement (70, 80) connected to it; a photovoltaic panel (10) mounted symmetrically on the said ball joint (50) for continuously tracking the sun in east-west and north-south direction to continually obtain the solar energy; a switch stand (150) provided on the said cylindrical rod (130) for mounting switches (140, 140’), pinion stand (110) and pulley (120); a cable (100) connecting the fiber cylinder (60) to the photovoltaic panel (10) with one end of the cable connected from the fiber cylinder (60) to the photovoltaic cell (10) and other end of the cable (100) connected to the photovoltaic panel(10) through a pulley (120) and sensors (30, 30’) provided on the photovoltaic panel for continually tracking the position of sun and generating the instructions for transferring fluid from tank (T2) to tank (T1) or from tank (T1) to tank (T2), and continually moving the photovoltaic panel (10) to track the sun for absorbing the incident solar radiations and moving back the photovoltaic panel (10) to its starting position facing east in the morning.
2) The system as claimed in claim 1 wherein, cable (100) moves over a pulley (120) in inwards or outwards direction allowing one end of PV module to move down when another end moves upward.
3) The system as claimed in claim 1 wherein, the solenoid valve is operated by a sensor (30) which continuously senses the sun position and when direct radiation from the sun falls on a sensor, the solenoid valve opens and fluid transfers to tank (T2) from tank (T1) causing the fluid level to go down in tank (T1) and fiber cylinder to move in downward direction and a cable attached to a cylinder left corner is shifted down and forces the PV panel down wherein simultaneously the same length of cable is released at right corner of fiber cylinder to move the PV panel in upward direction.
4) The system as claimed in claim 1 wherein, the rack (70) is vertically attached to a fiber cylinder (60) and a pinion (80) is connected to the rack (70), wherein the movement of fiber cylinder (60) rotates the pinion (80) in clock wise and anti clock wise direction and wherein from morning to noon position of sun, fiber cylinder (60) travels down half of its path and the cable (100) gradually and momentarily moves the PV panel from 0 degree to 23.5 degree towards south direction and during next half from noon-evening cylinder completely moves down and forces the pinion to complete its full rotation and the PV panel gets its original position in the evening.

5) Method of operating the floating tank type solar tracking system, the method comprising:
Turning ON the pump in the morning based on the instructions from the sensor (30’) when the sunlight is incident on sensor (30’) to transfer a fluid from tank T2 to tank T1 and begin the continuous sun tracking; moving the photovoltaic panel (10) to continually track the sun along east-west and north-south directions using the cable and the pulley mounted over the floating fiber tank (170) to allow the sun radiations to be incident continually perpendicularly on the sensor (30), and sensor (30) opening a valve to flow fluid from tank T1 to T2 making the PV panel orient at 900 to sun position;
pressing the switches (140, 140’) using the PV panel in the evening where switch (140) immediately turns off the sensor (30) and solenoid valve and the switch (140’) activates the power supply of sensor (30’) to turn ON a pump with the first incident sun radiation;
wherein sensor (30) which continuously senses the sun position and when direct radiation from the sun falls on sensor (30), sensor (30) opens the solenoid valve and fluid transfers to tank (T2) from tank (T1) causing the fluid level to go down in tank (T1) and fiber cylinder to move in downward direction and a cable attached to a cylinder left corner is shifted down and forces the PV panel down wherein simultaneously the same length of cable is released at right corner of fiber cylinder to move the PV panel in upward direction.
6) The method as claimed in claim 5 wherein, the linear movement of the cylinder is converted into a rotational movement using rack and pinion, again the rotational movement of pinion is converted into a linear movement by connecting metal rod/shaft at radial end of pinion.
7) The method as claimed in claim 5 wherein, cable (100) moves over a pulley (120) in inwards or outwards direction allowing one end of PV module to move down when another end moves upward.
8) The method as claimed in claim 5 wherein, the solenoid valve is operated by a sensor (10) which continuously senses the sun position and when direct radiation from the sun falls on a sensor, the solenoid valve opens and fluid transfers to tank (T2) from tank (T1) causing the fluid level to go down in tank (T1) and fiber cylinder to move in downward direction and a cable attached to a cylinder left corner is shifted down and forces the PV panel down wherein simultaneously the same length of cable is released at right corner of fiber cylinder to move the PV panel in upward direction.

9) The method as claimed in claim 5 wherein, from morning till noon, during the half movement of fiber cylinder (60), the photovoltaic panel (10) moves from 0 degree to 23.5 degree towards south direction and during next half from noon-evening fiber cylinder (60) completely moves down and the photovoltaic panel (60) gets its original position in the evening.

,TagSPECI:FIELD OF THE INVENTION
The invention generally relates to a solar tracking system. More particularly, the invention relates to floating tank type solar tracking system for tracking the sun that gradually shifts towards the south up to 23.5 degree in winter season.

BACKGROUND OF THE INVENTION
Recently, it has been required to develop a solar tracking technology of concentrating type for effectively obtaining radiant energy from the sun. For these purposes, for example, various tracking systems each utilizing a driving motor and electronic control devices therefore were developed or proposed. However, these tracking systems require a continuous electric power supply and are somewhat complicated for technology transfer to developing countries where sunshine is so abundant that the utilization of solar energy is favorable while, however, electric power supply networks have not yet been adequately developed.
Solar power concentrators such as reflective dishes, lenses, and solar traps need to focus the sun's light on a single point or small area and operate best when aimed directly at the sun. For this reason many types of tracking devices have been developed to follow the sun from east to west each day and adjust also for seasonal changes in the sun's trajectory. While many systems utilize motorized tracking systems and similar mechanically powered control systems.
Examples of prior-art solar-tracking systems are shown in the following U.S. patents. In U.S. Pat. No. 5,317,145, the solar-tracking system uses a loop-control tracking with two linear actuators to control elevation, or latitude, and to control rotation. The system of this patent has a maximum of 120-degree rotational tracking that translates to eight hours per day maximum, and has a vertically-oriented support.
U.S. Pat. No. 4,172,739 discloses a similar system also using a perfectly-vertical support shaft.
U.S. Pat. No. 5,600,124 discloses a sun-tracking system using cam and roller principle and gravity. Like the other systems, a perfectly vertical support shaft is used.
U.S. Pat. No. 4,995,377 discloses a solar collector having photovoltaic panels that track the latitude of the sun. In this system, also, the support shaft is perfectly vertically-oriented.
U.S. Pat. No. 5,253,637 discloses a sun-tracking system based on a linear actuator for elevational tracking, and another linear actuator for azimuthal axis. The support is also vertically-oriented.
The previous solar tracking systems outlined in U.S. Pat. No. 2,999,943 and the improvements outlined in U.S. Pat. No. 4,275,712 do not address the needs of a solar concentrating device, which requires two degrees of tracking motion. The previous systems are limited to one degree of rotational motion and thus can only track one degree of the sun's motion across the sky.
For the purposes of a solar concentrator, which focuses the light on a single point or small area, the system is required to track two degrees of the sun's translational motion in the plane parallel to the earth's surface.
There exists no tracking device that tracks both the sun's East to West movement and the sun's North and South movement, using the principles set forth herein.
From fig.1, it is observed that in summer, the sun is at zenith (on head) and gradually shifted towards the south up to 23.5 degree in winter season. This variation in sun path decreases the incident sun radiation as a result the PV panel output is also decreases. To capture the maximum sun radiation or increases the PV panel output, a dual axis sun tracker is required. Also none of the prior art teaches floating tank type solar tracking system that is economical and efficient dual axis sun tracking system, which tracks a sun continuously throughout a day.

SUMMARY OF THE INVENTION
One object of the instant invention is to provide a dual axis sun tracking system keeps the PV panel facing towards sun in both east-west and north-south direction.
Another object of the present invention is to provide a floating tank type solar tracking system that is economical and efficient dual axis sun tracking system, which tracks a sun continuously throughout a day.
Yet another object of the present invention is to provide a solar tracking system having at least two tanks (T1 and T2) connected to each other using a first pipe and a second pipe and a pump for transferring fluid from tank (T2) to tank (T1) through the said first pipe, and a solenoid valve mounted on the said second pipe for transferring the fluid back from tank (T1) to tank (T2). A floating fiber tank (170) floats in the tank (T1) and moves up and down during solar tracking based on the amount of liquid filled in the tank (T1). Supporting rods (160) have their one end mounted on the floating fiber tank (170) and a cable hook (240) mounted on the other end of the supporting rods (160). A cylindrical rod (130) is mounted on the tank (T1) and have a fiber cylinder (60) with a ball joint (50) mounted on the cylindrical rod (130) wherein the fiber cylinder (60) having a rack and pinion arrangement (70, 80) connected to the cylindrical rod. A photovoltaic panel (10) is mounted symmetrically on the said ball joint (50) for continuously tracking the sun in east-west and north-south direction to continually obtain the solar energy. A switch stand (150) provided on the cylindrical rod (130) for mounting switches (140, 140’), pinion stand (110) and pulley (120). A cable (100) connecting the fiber cylinder (60) to the photovoltaic panel (10) has its one end connected from the fiber cylinder (60) to the photovoltaic cell (10) and other end of the cable (100) is connected to the photovoltaic panel(10) through a pulley (120). Sensors (30, 30’) provided on the photovoltaic panel for continually tracking the position of sun and generating the instructions for transferring fluid from tank (T2) to tank (T1) or from tank (T1) to tank (T2), and continually moving the photovoltaic panel (10) to track the sun for absorbing the incident solar radiations and moving back the photovoltaic panel (10) to its starting position facing east in the morning.
Yet another object of the instant invention is to provide a method of operating the floating fiber type solar operating system. The method includes turning ON the pump in the morning based on the instructions from the sensor (30’) when the sunlight is incident on sensor (30’) to transfer a fluid from tank T2 to tank T1 and begin the continuous sun tracking. Providing an arrangement to allow the sun radiations to be incident continually perpendicularly on the sensor (30), and sensor (30) opening a valve to flow fluid from tank T1 to T2 making the PV panel orient at 900 to sun position. Moving the photovoltaic panel (10) to continually track the sun along east-west and north-south directions using the floating fiber tank(170) and the rack-pinion arrangement (70, 80) till the evening and pressing the switches (140, 140’) using the PV panel in the evening where switch (140) immediately turns off the sensor (30) and solenoid valve and the switch (140’) activates the power supply of sensor (30’) to turn ON a pump with the first incident sun radiation. A switch 140 is a push to OFF type switch and 140’ is a push to ON type switch. PV panel push the switches, 140 gets OFF to avoid unwanted activation of controller which helps to reduce power consumption and 140’ gets ON to takeover a controller till first incident sun radiation. Similarly on releases, 140 gets ON and 140’ gets OFF.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig.1 shows the trajectory of sun. In summer, the sun is at zenith (on head) and gradually shifted towards the south up to 23.5 degree in winter season.
Fig. 2 shows east-west axis solar tracking system according to an embodiment of the present invention
Fig. 3 shows north-south axis solar tracking system according to an embodiment of the present invention
Fig.4 shows solar tracking starting position according to an embodiment of the present invention
Fig.5 shows three different positions of solar tracker along with the different fluid levels from beginning of the day towards end of the day
Fig.6 shows PV module movement.
Fig, 6 (b) shows cylinder shifted downward by ‘l ’length, the distance between a pulley and cylinder bottom will be reduce by ‘l ’length.

DETAILED DESCRIPTION
Floating tank type solar tracking system is provided. It is very economical and efficient dual axis sun tracking system which tracks a sun continuously throughout a day. This technique definitely provides a successful tracking option for a single PV panel as well as for a PV panel array. Basically a system works on floating concept in which weight of the PV panel carried by plastic tank filled with air floating on a fluid. A tank float on a fluid due to a buoyant force acts in upward direction. Floating of tank is dependent on its area, weight and fluid density. In fig.2, a fiber cylinder is connected to a floating plastic tank, a cylinder moves up and down according to a fluid level of tank. A fluid level has decrease or increase depends on the opening of a solenoid valve and fluid pump. Solenoid Valve is operated by a Sensor 30 which continuously senses the sun position. When direct radiation from the sun falls on a sensor, solenoid valve open and some fluid has transfer to tank 2 from tank 1. This cause the fluid level goes down and fiber cylinder moves in downward direction. A cable attached to a cylinder left corner shifted down and force the PV panel moves down. Simultaneously the same length of cable releases at right corner of fiber cylinder which helps to move the PV panel in upward direction. Because the both end of the PV panel attached by cable which doesn’t allow the PV panel to change its direction due to wind gust.
Particularly, the system consists of at least two tanks (T1 and T2) connected to each other using a first pipe and a second pipe and a pump for transferring fluid from tank (T2) to tank (T1) through the said first pipe, and a solenoid valve mounted on the said second pipe for transferring the fluid back from tank (T1) to tank (T2). A floating fiber tank (170) that floats in the tank (T1) and moves up and down during solar tracking based on the amount of liquid filled in the tank (T1). Supporting rods (160) are provided with their one end mounted on the said floating fiber tank (170) and a cable hook (240) mounted on the other end of the supporting rods (160). A cylindrical rod (130) is mounted on the tank (T1) and a having fiber cylinder (60) with a ball joint (50) mounted on the cylindrical rod (130), the fiber cylinder (60) has a rack and pinion arrangement (70, 80) connected to it.
A photovoltaic panel (10) is mounted symmetrically on the said ball joint (50) for continuously tracking the sun in east-west and north-south direction to continually obtain the solar energy. A switch stand (150) is provided on the cylindrical rod (130) for mounting switches (140, 140’), pinion stand (110) and pulley (120). A cable (100) connecting the fiber cylinder (60) to the photovoltaic panel (10) with one end of the cable connected from the fiber cylinder (60) to the photovoltaic cell (10) and other end of the cable (100) connected to the photovoltaic panel(10) through a pulley (120) and sensors (30, 30’) are provided on the photovoltaic panel for continually tracking the position of sun and generating the instructions for transferring fluid from tank (T2) to tank (T1) or from tank (T1) to tank (T2), and continually moving the photovoltaic panel (10) to track the sun for absorbing the incident solar radiations and moving back the photovoltaic panel (10) to its starting position facing east in the morning.
In fig.3, a pinion is connected to a cylinder, the movement of cylinder causes to rotate a pinion in clock wise and anti clock wise direction. A rail of teeth called rack is vertically attached to a fiber cylinder having a length slightly more the circumference of pinion. From morning to noon position of sun, cylinder travel down half of its path as shown in fig. 3 (a) and (b). Simultaneously pinion completes its half rotation (i.e. 0 degree to 180 degree) in anti-clock wise direction. A metal rod gradually and momentarily moves the PV panel from 0 degree to 23.5 degree towards south direction. Again for the next half path, cylinder completely moves down and forces the pinion to complete its full rotation (i.e. 180 degree to 360 degree). This makes the PV panel to get its original position till evening as shown in fig. 3 (b), (c), (d), (e), (f) and (g).
Working of the preferred embodiment:
From fig.4, in early morning, Sensor 30’ available in sunlight incident position turn on a pump to transfer a fluid from tank T2 to tank T1 in order to get beginning position of sun tracking as shown in fig.5 (a).
Now a sun tracking starts according to a sun position which is continuously sensed by a sensor 30. An arrangement is made to allow a sun radiation incident on sensor 30 perpendicular as shown in fig.5.
Sensor 30 on bright condition opens a valve to flow fluid from tank T1 to T2. This makes the PV panel orient 90 degree to sun position.
From fig.5(c), in evening when PV panel press the switch 140 and 140’, where switch 140 immediately turn off the Sensor 30 and solenoid valve. Similarly switch 140’ activate the power supply of Sensor 30’ which turn ON a pump with the first incident sun radiation.
Although several embodiments have been described in some detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.
PV module connected to the bottom end of cylinder through Cable/belt. As shown in fig.6, a cylinder moves downward by distance ‘ l ’, a Cable/belt attached to a cylinder travel a same distance ‘ l ‘ in downward direction.
The ‘l ’length of Cable/belt will be shifted downward but after a pulley (120) a same length of Cable/belt will be shifted upward. Amount of distance travel by cylinder in downward direction release an equal amount of Cable/belt shifted in upward direction. So the downward movement of PV module in left side is equal to the upward movement at right side.
In other way, PV module movement can understand by fig, 6. In fig, 6 (b), cylinder shifted downward by ‘l ’length, the distance between a pulley and cylinder bottom will be reduce by ‘l ’length. This decrease in ‘l ’length of Cable/belt at left side of pulley will be found as an increase in ‘l ’length of Cable/belt at right side of pulley. Pulley converts the downward movement of cylinder in to an increase in length of Cable/belt in upward direction.
The whole unit should be placed on and underground perpendicular to the ground i.e. 90o to the ground. Half of the unit should be installing underground due to following reasons-
Both the water tanks should be installing underground to provide best support to the frame. This provides strength to the unit to survive under gusty wind condition.
Underground installation also decreases the actual height of the system which provides less interaction with gusty wind and helps to minimize wind adverse effects.
Pivot/ball joint: Pivot/ball joint is used to orient the PV module always in sun direction. It provides a hemispherical movement of PV module. Means a PV module moves in all direction in a hemisphere.
A ball joint consist of bearing stud and sockets enclosed in a casing; all these parts are made of steel. Ball joint is used to allowing free movement in two planes at the same time, including rotating in those planes. Its working is similar to human neck. In automobile, it is used between wheel and suspension.
South tilt position: Tilt position of PV module in south direction can be understood by fig.3. A linear movement of cylinder is converted into a rotational movement using rack and pinion; again the rotational movement of pinion is converted into a linear movement by connecting metal rod/shaft at radial end of pinion. Working principle is similar to IC engine, in which linear movement of piston inside a cylinder is converted into a rotational movement at crank shaft.
As shown in fig, 3, a various position of PV panel towards south direction. A calculation enclosed earlier to explain the movement of PV module towards south direction. A PV panel travel an ‘S’ radial distance to achieve its 23.5 degree south position from 0 degree position. So please take a reference of design calculation of pinion.
The greatest advantage of this sun tracking technique, the efficiency of system will be increases with increases the PV module up to a certain extent. Because the energy consumed by control circuit is 24 W-hr per day and it is fixed. Only the opening period of solenoid valve and turn ON period of fluid pump will increases with the amount of fluid required to be shifted between tanks.
Entire weight of the body carried out by a fixed/static cylindrical rod and rod connected to a center of gravity position of a body. Thus the body is in equilibrium position; a very little force is sufficiently changing its state of equilibrium and brings it to in a non-equilibrium state. A very less effort required by dynamic/moving parts of a unit. This feature of a system makes it innovative and isolates it from other sun tracking system.
Some of the salient features of the present invention are as follows:
A controller has two separate circuits; one for sensor 30 and another for sensor 30’. An arrangement made it possible to activate one circuit at a time reducing energy consumption.
Floating tank 170 loaded by only that much amount of weight which is required to unbalance the arm of a PV module and not to carry out a total system load.
Cable/ belt moves over a pulley; inwards and outwards direction of belt movement are opposite to each other. So one end of PV module moves down and another end moves upward by belt and pulley action.
Half of the unit placed over a ground and rest of the unit including tanks inside the ground.
Pivot/ ball joint are made of steel and find application in automobile. So it is efficiently handling that much amount of weight.
This technique never falls under any design limitation.
It is definitely scalable and feasible for small as well as large size PV modules. It is most advantageous for a large sized PV module. It may find limitation if entire weight carried out by a moving parts. But this is not done in this technique.
A step wise design and development process specifically showing the development of each unit for a 40 Watt PV module has been described. System design is on the basis of weight of the PV module and not on its dimension. If size of the PV module increases, height of the cylindrical rod, height of cylinder and tanks may also increases. In one case, two 20 Watt PV panel installed having a weight 5.6 Kg. So the force required for changing its state of equilibrium is calculated is 1.35 Newton. Therefore all the dimensions have taken under consideration of 40 Watt PV module. Actual force is required less as compare to the calculated force. There is a minimum force generated by a body weight that exerts in downward direction. This force is sufficient to move the PV module of capacity between 20 Watt and 150 Watt. Current unit is still able to track the sun with 150 Watt PV module.