WO2016145184A2

WO2016145184A2 - A system and method for continuously reorienting the surface of a solar collection device

Info

Publication number: WO2016145184A2
Application number: PCT/US2016/021753
Authority: WO
Inventors: Gina TIBBOTT
Original assignee: KRISHNAN, Neel
Priority date: 2015-03-10
Filing date: 2016-03-10
Publication date: 2016-09-15
Also published as: WO2016145184A3

Abstract

This application discloses a system and method for continuously reorienting the light sensitive upper surface of a solar collection device, such as a solar panel, parabolic or other solar radiation collector, in response to the movement of the sun that uses less energy than existing methods. The system is characterized by a plurality of light sensors arranged at an angular displacement to a light sensitive upper surface of a solar collecting device, and a software/programming routine for translating outputs of the light sensors into activations of actuators to move the light sensitive upper surface of the solar collecting device in response to sun movements.

Description

A SYSTEM AND METHOD FOR CONTINUOUSLY REORIENTING THE SURFACE

OF A SOLAR COLLECTION DEVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No.

62/130,986, filed March 10, 2015, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to solar tracking for solar collection devices, such as terrestrial solar cells, solar arrays and solar panels.

BACKGROUND OF THE INVENTION

Accurate solar tracking is important for solar power generation because the amount of power generated by a given solar cell or collected by a solar collector is related to the amount of sunlight that strikes its surface. A technical challenge arises from the fact that the sun is continuously moving, while the orientation of the panel or collector towards the sun that maximizes solar energy collection is fixed. Existing approaches to this problem use mechanical collector housings moved by motors controlled by computer algorithms that utilize memory and data about sun movements in conjunction with internal clocks to predict and track the sun's movement and reorient the panel or collector in response, losing some of the energy gained through solar tracking to powering the motors and the computer chip (e.g., U.S. Patent No. 8,513,514).

Existing systems for achieving solar tracking have utilized structures to mount the panels to gear systems or mechanical arms, and move them mechanically in the two axes necessary to track the sun— the sun's elevation and azimuth (e.g., U.S. Patent No. 8,513,514). To determine the angle of these axes necessary to achieve optimal sun exposure, computer circuits running prediction algorithms utilizing geographical and temporal data in conjunction with an internal clock have been used to determine the sun's future location, which activate motors to move or rotate the panels about their two axes. This approach has the drawback of requiring the use of electrical energy to power the motors to move the panels about their axes of movement and run the tracking algorithms, thus negating some of the energy production benefits of solar tracking, and of requiring potentially large amounts of regionally specific data to implement. It also presents significant maintenance costs to keep the gearing systems lubricated and working properly. There is also a small technical obstacle presented by the need to keep the internal clock properly calibrated and synchronized. SUMMARY OF THE INVENTION

A solar tracking system for reorienting a solar radiation-absorbing device in response to sun movements is disclosed, which utilizes only extant sunlight to determine the tracker orientation, requiring no memory of past sun movements, geographic location, or time of year.

In one aspect, the present invention provides a solar tracking system comprising: a plurality of light sensors arranged at an angular displacement to a light sensitive upper surface of a solar collecting device fixed on a support structure, and a processor equipped with a software program for translating outputs of the light sensors into activations of actuators to move the light sensitive upper surface of the solar collecting device in response to sun movements through moving the support structure.

In some embodiments, the alignment of the upper light sensitive surface is controlled through determining the intensity of reading of each of the light sensors relative to each other and firing the electromagnets to cause the ball shaped casing to move so that the intensity of each reading for each of the light sensors is approximately equal.

In some embodiments, the light sensors comprise one or more photo-electric devices that translate(s) luminous intensity into electric current or resistance.

In some embodiments, the photo-electric device comprises one or more photoresistors or photo-diode circuits.

In some embodiments, the light sensors are so oriented that each sensor faces at an angle to the side of the face of the solar collection device to which it is attached, with the sensing side facing away from the solar collection device.

In some embodiments, the present invention provides a solar tracking system, comprising:

a ball shaped casing comprising a magnetic or electro-conductive surface and a top end configured to support a solar collecting device, the solar collection device comprising a light sensitive upper surface and a plurality of light sensors arranged at an angle with respect to the light sensitive upper surface;

a container having an opening and a recess, wherein the opening is configured to accept a lower portion of the ball shaped casing, and wherein the recess is configured to hold a liquid medium;

a plurality of electromagnets capable of providing an electro-motive force to the ball shaped casing; and

a processor and non-transitory machine readable memory, wherein the memory comprises program instructions to cause the processor to align the upper light sensitive surface in an optimal position relative to the angle of incidence of incoming sunlight.

In one embodiment, the solar tracking system includes two or more sets of two photoresistor sensors or other light sensors placed in housings on opposing ends of the absorbing device's absorbing surface at equivalent or roughly equivalent angular displacements to the part of absorbing face to which they are attached. The tracking system utilizes the inputs of these sensors to conditionally power motors or other actuators that reorient the device so as to achieve a roughly equivalent reading across all the sensors, this condition being equivalent to a roughly orthogonal orientation of the absorber surface to the angle of incident solar radiation.

In one embodiment, the recess of the container is configured to hold a liquid medium having density that is substantially the same or greater than the density of the ball shaped casing so that the ball shaped casing floats in the liquid medium and is capable of movement with little or no friction between the ball shaped casing and the container.

In one embodiment, a number of electromagnet arrays are positioned with each fixed on one side of the container and capable of providing an electro-motive force to the ball shaped casing. A processor and memory includes control software that causes the processor to align the upper light sensitive surface so that it is in an optimal position relative to the angle of incidence of incoming sunlight by determining the intensity of the reading of each of the angled light sensors and firing the electromagnets to cause the ball shaped casing to move so that the readings of all of the light sensors are approximately equal to each other.

In another aspect, the present invention provides a solar energy collection system, comprising a solar tracking system of the present invention. Examples of the solar energy collection system of the present invention include, but are not limited to, flat panel solar collector, parabolic panel solar collector, or the like.

In another aspect, the present invention provides a method of maximizing solar collection for a solar collecting device, the method comprising use of the solar tracking systems described herein.

Other aspects and advantages of the present invention will be better appreciated through the following detained description, drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A illustrates a top view of a flotational sun tracking device.

FIG. IB illustrates a side view of a flotational sun tracking device.

FIG. 1C illustrates a side view cross section of a flotational sun tracking device.

FIG. ID illustrates a top view of a flotational sun tracking device without a solar panel.

FIGs. 2A, 2B and 2C illustrate diagrams of magnet firing, stopper, and ball movement from a top view.

FIGs. 2D, 2E and 2F illustrate diagrams of magnet firing, stopper, and ball movement from a side view.

FIGs. 3A, 3B and 3C illustrate diagrams of sun tracking mechanics.

DETAILED DESCRIPTION OF THE INVENTION

This application relates to solar tracking for solar collection devices, such as flat solar-voltaic and parabolic trough solar thermal collectors, or any other solar collector that benefits from solar tracking in which the radiation must be focused on the part of the collector facing the sun. The apparatus and process described herein may also be adapted for solar thermal power collection where the solar radiation must pass through the collector housing to a focusing point on the opposite side of the collector to the sun, or to a fixed point below the collector.

In some embodiments, said angle is 45-degree or an angular displacement between 0 and 90 degrees that allows appropriate differential readings across the sensors to be captured.

In some embodiments, the light sensors are used to control a computational process through a computer chip or an analog electrical circuit that pulses the electromagnets in order to achieve approximately equal luminous intensity across the sensors.

In some embodiments, the light sensors record the intensity of the ambient light and use it to toggle a resistance circuit that controls power to the actuators for moving the support structure and the solar collection device along the elevation and azimuth of the sun's path.

In some embodiments, the system contains four sensors and two arrays of electromagnets so that the solar collection device is capable of achieving tracking in three dimensions along the sun's azimuth and elevation.

In some embodiments, the light sensors are oriented on the solar collection device with one sensor on each of the top and bottom of the solar collection device to control movement in one axis and two sensors on the sides to control the other axis, wherein the combined action of the movement in both axes provides the three dimensional rotation required for sun tracking. In some embodiments, the actuators comprise a plurality of electromagnets capable of providing an electro-motive force to move the solar collecting device through the support structure.

In some embodiments, the software program comprises a machine readable instruction to control movement of the supporting structure.

In some embodiments, the support structure comprises a ball shaped casing having a magnetic or electro-conductive surface; the actuators comprise a plurality of

electromagnets capable of providing an electro-motive force to move the ball shaped casing; and the software program comprises a non-transitory machine readable memory, wherein the memory comprises program instructions to cause the processor to align the upper light sensitive surface in an optimal position relative to the angle of incidence of incoming sunlight.

In one embodiment of the present invention, the processor aligns the upper light sensitive surface through determining the intensity of reading of each of the light sensors relative to each other and firing the electromagnets to cause the ball shaped casing to move so that the intensity of each reading for each of the light sensors is approximately equal. In another embodiment of the present invention, the ball shaped casing is covered with a weakly magnetic substance or imparted a small electrical charge via an electrode applied to the ball.

In another embodiment of the present invention, the ball shaped casing is hollow or solid and balanced by a counterweight anchored at the bottom end of the casing.

In another embodiment of the present invention, the ball shaped casing is made of a conductive material so that the ball is magnetized via a small electric current applied to the liquid medium, and the liquid medium allows the flow of electric current.

In another embodiment of the present invention, the ball shaped casing is made of metal or plastic.

In another embodiment of the present invention, the ball shaped casing is of an appropriate size and material relative to density and volume of the liquid medium such that it floats in the liquid medium with half or more of its surface area floating above the surface level of the liquid medium, which allows the light sensitive upper surface of the solar collection device to move nearly 180 degrees in relation to the sun's azimuth and elevation.

In another embodiment of the present invention, the counterweight has a weight approximately the same as the weight of the solar collection device.

In another embodiment of the present invention, the counterweight comprises a sealable cavity that can be filled with a variable amount of the liquid medium or a heavier liquid medium to achieve a desired counterweight.

In another embodiment of the present invention, the ball-shaped casing is moved by the electromagnets firing at the exterior surface of the ball, in order to minimize frictional, inertial and gravitational resistance in moving the panel.

In another embodiment of the present invention, the rotation of the ball-shaped casing is controlled by a control process that converts the inputs of four photoresistors or other luminous intensity-sensing circuits into short magnetic pulses.

In another embodiment of the present invention, the four photoresistors or other luminous intensity-sensing circuits are located on the edges of the solar collection device at a consistent angular displacement to the portion of the device's face to which they are attached. In another embodiment of the present invention, said plurality of electromagnets comprises four electromagnets, each fixed on one side of the container.

In another embodiment of the present invention, the four electromagnets are situated on the four sides of the ball shaped casing in substantially the same horizontal plane.

In another embodiment of the present invention, the plurality of electromagnets rotate the ball about its center by applying a substantially equivalent same-pole force (repellant magnetic force) or opposite-pole force to the ball at points just off of center from each other on either side.

In another embodiment of the present invention, two of these electromagnets rotate the ball horizontally with respect to the earth's surface, and the other two rotate it vertically and substantially perpendicular to the horizon line, and the combined action rotates the panel surface in relation to the sun's elevation and azimuth.

In another embodiment of the present invention, the container is barrel-like or bowl -like, having an edge of the mouth of the barrel or bowl almost touching the ball shaped casing.

In another embodiment of the present invention, the solar tracking system further comprises a plurality of stoppers or tension mechanisms to hold the ball in place so that the ball does not move unless acted on by outside forces.

In another embodiment of the present invention, said plurality of stoppers or tension mechanisms is four and each of the four stoppers or tension mechanisms is on one of the four sides of the ball shaped casing in a plane parallel to the ground,

In another embodiment of the present invention, the edges of the solar collection device protrude beyond the diameter of the opening of the container, or the stoppers protrude from the surface of the ball so that the solar collection device is prevented from moving beyond this range into the liquid medium.

In another embodiment of the present invention, the tension mechanism is aligned with the electromagnets to apply friction or mechanical force to the edges of the ball shaped casing to absorb the angular momentum imparted by these forces and thus hold the ball in place when the electromagnets are not firing.

In another embodiment of the present invention, the tension mechanism also serves to stop the ball's rotation after it is rotated by the force of the electromagnets. In another embodiment of the present invention, the tension mechanism comprises a device selected from the group consisting of spring assemblies, ball-and-socket joints, and spring-loaded rubber pads, which applies a friction and/or mechanical force to the edges of the ball in order to hold it in place and/or to stop its rotation after the electromagnets stop firing.

In another embodiment of the present invention, said device of the tension mechanism remains in continuous contact with the ball shaped casing if the force exerted by the electromagnets on the ball is greater than the force of the tension mechanism on the ball; or alternatively, the tension mechanism is capable of removing or decreasing the tension exerted on the ball at the exact time when the electromagnets fire to move the ball.

In another embodiment of the present invention, the opposite pole of the electromagnets is oriented to pull a piece of metal connected through a small gear to the back of the tension mechanism on a spring-loaded plunger, so that when the electromagnets fire to move the ball, they simultaneously release the tension mechanism, and when the electromagnets stop firing the spring, they reengage the stopper of the tension mechanism.

In another embodiment of the present invention, the surface of the ball shaped casing is covered in small grooves to allow the tension mechanism to move pins that lock the ball in place.

In another embodiment of the present invention, the electromagnets are connected via a circuit to the light sensors oriented approximately at mid-points of the four edges of the solar collection device.

In another embodiment of the present invention, the light sensors comprise one or more photo-electric devices that translate(s) luminous intensity into electric current or resistance.

In another embodiment of the present invention, the photo-electric device comprises one or more photoresistors or photo-diode circuits.

In another embodiment of the present invention, the light sensors are so oriented that each sensor faces at an angle to the side of the face of the solar collection device to which it is attached, with the sensing side facing away from the solar collection device. In another embodiment of the present invention, the angle of the light sensors is 45-degree or an angular displacement between 0 and 90 degrees that allows appropriate differential readings across the sensors to be captured.

In another embodiment of the present invention, the light sensors are used to control a computational process through a computer chip or an analog electrical circuit that pulses the electromagnets in order to achieve approximately equal luminous intensity across the sensors.

In another embodiment of the present invention, the light sensors record the intensity of the ambient light and use it to toggle a resistance circuit that controls power to the electromagnets for moving the ball shaped casing and the solar collection device along the elevation and azimuth of the sun's path.

In another embodiment of the present invention, the solar tracking system comprises four sensors and two arrays of electromagnets so that the solar collection device is capable of achieving tracking in three dimensions along the sun's azimuth and elevation.

In another embodiment of the present invention, the light sensors are oriented on the solar collection device with one sensor on each of the top and bottom of the solar collection device to control movement in one axis and two sensors on the sides to control the other axis, wherein the combined action of the movement in both axes provides the three dimensional rotation required for sun tracking.

In another embodiment of the present invention, the liquid medium has a density substantially same as or greater than the density of the ball shaped casing so that the ball shaped casing floats in the liquid medium and is capable of movement with little or no friction between the ball shaped casing and the container.

In another embodiment of the present invention, the liquid medium is water or another low-viscosity liquid.

In another embodiment of the present invention, the edges of the solar collection device protrude from the edge of the ball shaped casing, or alternatively, the solar collection device is embedded in the ball shaped casing.

Other embodiments of the present invention include a combination of any one or more embodiments described herein. In another aspect, the present invention provides a solar energy collection system, comprising a solar tracking system according to any one of the embodiments described herein, or any combinations thereof.

In one embodiment of the present invention, the energy collection system is a flat panel collector or a parabolic trough collector.

In another aspect, the present invention provides a method of maximizing solar collection for a solar collecting device, the method comprising use of the solar tracking system according to any one of embodiments described herein or any combination thereof.

Terrestrial solar power generation systems such as solar-voltaic and solar-thermal systems utilize sun collection devices that are flat or parabolic in shape. For these and other similar devices, the amount of energy collected is related to the amount of sunlight striking their surface. For flat panels such as Fresnel lens, flat panel collectors, and other solar-voltaic and solar-thermal cells, the amount of energy collected at any given moment of the day is maximized if the collecting face of the panel is oriented orthogonal to the direction of the sunlight. Given that the sun is constantly moving, solar energy collection could therefore be maximized if the panel is able to track the sun such that the face of the panel is always orthogonal to the direction of the sunlight. For parabolic and dish collectors a similar optimal orientation for energy collection can be achieved via sun tracking by keeping them in an orientation that maximizes the amount of sunlight striking their surface.

Thus, the present invention relates generally to solar tracking for use with one or more terrestrial solar cell panels or other solar collectors that convert sunlight into electrical energy or serve to focus solar radiation for any other purpose. The system can be utilized with solar-voltaic, solar thermal and solar thermo-electric devices. The invention is further illustrated below by referring to the drawings as non-limiting examples.

The term "a," "an," or "the," as used herein, represents both singular and plural forms. In general, when either a singular or a plural form of a noun is used, it denotes both singular and plural forms of the noun.

Referring to FIGs. 1 A-1D, an example approach is described that saves energy and maintenance costs over existing approaches by utilizing a magnetized floating ball-like collector housing moved by fixed electric magnets 106 firing at the exterior surface of the floating ball 104, in order to minimize frictional, inertial and gravitational resistance in moving the panel 100. The electromagnets and stopper arrays 106, and thus the rotation of the ball 104 is controlled by a control process that converts the inputs of four specifically placed photoresistors or other luminous intensity-sensing circuits 102 located on the edges of the panel or collector 100 at a consistent angular displacement to the portion of the panel's face to which they are attached into short magnetic pulses 112 (FIG. IB and ID, top and side views), ideally implemented using a simple analog electrical circuit instead of by computer chip. It thus tracks the sun without the need for memory of data about sun movements or geographical location of the device, internal clocks, or complex prediction algorithms, and could be implemented on a simple electrical circuit or with very minimal code (outlined below) in existing computer languages run on a small computer chip.

The preferred embodiment set forth in this disclosure attempts to minimize the drawbacks of existing approaches described above through an approach that takes advantage of the ease of rotating smooth circular objects floating in water or another low- viscosity liquid medium 110. In this approach, the panel 100 is affixed to a circular ball 104 made of any of a number of suitable solid materials such as metals, Styrofoam or plastics, that is countered-weighted by a weight 108 anchored on the opposite end of the ball 104 to where the panel 100 is fixed. The counterweight has a weight substantially equivalent to the weight of the panel or collector. The edges of the panel or collector 100 may protrude from the edge of the ball 104, as in FIGs. IB and C, or the panel may be embedded in the ball. The embodiments described in this document are not limited with regard to such configurations of the panel 100 and ball 104. The counterweight 108 may be, for example, a sealable hollow cavity that can be variably filled with the liquid medium 110 or a heavier liquid medium that can serve to achieve a variable counterweight 108. The size and material choice for the ball can vary to accommodate different panels and other collectors of different sizes and weights. For example, the flat panel collector 100 in FIGs. 1A-1D may be replaced with a parabolic trough collector without departing from the spirit of this disclosure. The ball 104 may be hollow or solid depending on these weight and size requirements.

The ball 104 is covered in a weakly magnetic substance such as magnetic tape or imparted a small electrical charge via an electrode applied to the ball 104, and allowed to float in a liquid medium 110 such as water in a barrel -like or bowl -like container 114 such that the edge of the mouth of the bowl or barrel almost touch the ball. For example, in FIG. IB, the ball 104 can also be magnetized via a small electric current applied to the liquid medium 110 if the ball 104 is made of a conductive material and the liquid 110 allows the flow of electric current. The ball 104 may be of an appropriate size and material so that its density is half or less than an equivalent volume of water or another liquid medium 110, such that it floats in the liquid medium 110 with half or more of the surface area of the ball 104 floating above the surface level of the liquid medium 110. This allows the panel 100 to move nearly 180 degrees in relation to the sun's azimuth and elevation as shown in FIGs. 3A-3C. Note that the magnet arrays 106 are not drawn to scale as the magnet arrays 106 could be quite small in relation to the whole unit. The protrusion of the panel 100 edges beyond the diameter of the opening of the container 114 holding the liquid medium 110, or optional stoppers protruding from the surface of the ball, prevents the panel or collector 100 from moving beyond this range and into the liquid medium 110.

Referring now to FIGs. 2A-2F, in a preferred embodiment, four electromagnets

206 are situated on the four corners of the ball in the same plane. These magnet arrays 206 rotate the ball 204 about its center by applying a substantially equivalent same-pole force

(the "N" stands for north in FIG. 2)— i.e. repellant magnetic force— or opposite-pole force to the ball 204 at points just off of center from each other on either side, for example, in clockwise displacement from a chord through the ball's center of maximum length perpendicular to the axis of rotation as shown in FIGs. 2B-C, E-F. Two of these electromagnets 206 rotate the ball horizontally with respect to the earth's surface, and the other two rotate it vertically, for example, perpendicular to the horizon line, and the combined action rotates the panel surface in relation to the sun's elevation and azimuth. The firing patterns 220 necessary to achieve these rotations are shown in FIGs. 2B-C, E-F, detailed further in the tracking control process section below.

Referring now to FIG. 2 A shows an example overview (without the panel) and FIG.

2D shows an example side view with the ball 204 at rest with stopper or tension mechanisms 207 on the four sides of the ball 204, in a parallel plane to the ground, holding it in place. Due to the counterweighting of the solar panel, the ball 204 does not move unless acted on by outside forces, and thus will tend to stay in a stationary orientation with respect to the sun unless acted on by wind or another disturbance. A tension mechanism

207 is aligned with the electromagnets 206 or placed elsewhere to apply friction or mechanical force to the edges of the ball 204 to absorb the angular momentum imparted by these forces and thus hold the ball 204 in place when the electromagnets 206 are not firing. The tension mechanism also serves to stop the ball's rotation after it is rotated by the force of the electromagnets. For example, tension mechanisms 207 such as small spring assemblies with ball-and-socket joints or other simple devices such as spring- loaded rubber pads may be used to apply a friction and/or mechanical force to the edges of the ball 204 in order to hold it in place, resisting wind forces, and to stop its rotation after the electromagnets 206 stop firing. If weakly frictious pads or a ball and socket joint are used for this tension mechanism 207, it can remain in continuous contact with the ball housing, in which case the force exerted by the electromagnets 206 on the ball 204 must be greater than the force of the tension mechanism 207 on the ball 204. Alternatively, the tension mechanism 207 could remove or decrease the tension exerted on the ball at exactly the time the electromagnets 206 fire to move the ball 204, for example, the opposite pole of the electromagnets 206 could be oriented so as to pull a piece of metal connected to a small gear, which is connected to the back of the tension mechanism 207, which is on a spring-loaded plunger. Thus when the electromagnets 206 fire to move the ball 204 they simultaneously release the tension mechanism 207, and when they stop firing the spring reengages the stopper of the tension mechanism 207. Alternatively, the surface of the ball 204 could be covered in small grooves so as to allow the mechanism 207 just described to move pins that lock the ball in place. The embodiments of the present disclosure are not limited in this regard.

The preferred embodiment described above moves the panel or collector for solar tracking with less energy expenditure than free-standing mechanical approaches due to the minimization of friction, inertial and gravitational forces resisting the movement of the panel or other solar collector. It also presents less maintenance requirements and costs than gearing systems, since there are no moving parts to replace or maintain, and photoresistor or photodiode circuits and electric magnets are inexpensive components.

The approach described above could be adapted to solar thermal technologies, including in cases where the target area for the thermal radiation remains fixed and the light must pass through the focusing panel to a target area beyond. For example, a hollow floating ball could be used and the light could be focused into a collimated beam by a lens near the ball's center, and the beam allowed to pass through the other end of the ball via a transparent surface or opening. The approach described above could be used for a flat panel solar collector, or for a parabolic collector of reasonably balanced weighting.

To move the panel in the housing described above, a control process which is the focus of this disclosure may be deployed to power the electric magnets to orient the ball in an optimal orientation for solar power collection, described in further detail below. To achieve this, existing systems have used computer chips running software that predict the sun's future position, and power motors to move the panels accordingly. The approach described below relies only on ambient sunlight to orient the housing towards the sun. It requires no adjustment for surrounding objects, no external data sources, and no special initial start-up condition:

The electric magnets 106, 206 or other actuators that move the solar collector are connected via a circuit to sensors 102 that measure luminous intensity ("light sensors" hereafter) oriented at approximate mid points of the four edges of the solar panel 100 or at similar points on the parabolic trough as shown in FIG. 1A. These sensors 102 could be photoresistor or photo-diode circuits, or any other photo-electric device that translates luminous intensity into current or resistance. The sensors 102 are oriented with each sensor face at an angle to the side of the face of the panel to which it is attached (FIG. 1 A) 302a, 302b, i.e. with the sensing side facing away from the solar collector 100, that is in the same general direction of the collector panel with respect to the sun (FIG. 1A) 302a 302b. For example a 45-degree angle may be used, or an angular displacement between 0 and 90 degrees that allows appropriate differential readings across the sensors to be captured. A barrier surrounding the entire unit could prevent light from reflective surfaces in the device's surroundings from interfering with the tracking process. These light sensors 102 are used to control a computational process described below, implemented via computer chip or ideally on a simple analog electrical circuit, that pulses the electromagnets 106, 206 or other actuators so as to achieve approximately equal luminous intensity across the sensors, a condition tantamount to orthogonal orientation to the sun for flat panels and similar optimal orientation for appropriately placed sensors on a parabolic or dish collector. The tracking system thus requires no special start-up orientation, unlike existing systems. If implemented on a simple electrical circuit instead of computer chip, the system could be run continuously to achieve the "terminal condition" of the control process, in a way described below. If implemented using a computer chip, it can be run iteratively at intervals that optimize minimal power usage across the day while running often enough to achieve fairly continuous solar tracking.

The system described herein could be run using a small battery or power generated by the solar power generation device itself, or by a battery powered by the solar energy device, thus minimizing the need for outside energy to power the tracking system. If used for a solar thermal generator, a small solar-voltaic cell connected to a battery could be used to power it.

Referring now to FIGs. 3A-C, the mechanics of the control process that is the object of this disclosure is shown in two dimensions, showing only one axis of rotation. The sensors 302 are oriented on the panel as in the panel top view in FIG. 1A with the sensors on the top and bottom of the collector governing movement in one axis and the two on the sides controlling the other axis. The combined action of the movement in both axes provides the three dimensional rotation required for sun tracking.

This section describes the solar tracking process used in the system and its implementation in detail. The essence of the process is its terminal condition: when the light sensors 302a, 302b situated on the panel 300 or other solar collector in the angular orientation with respect to the collecting face of panel 300 as shown give an approximately equal reading, the process assumes that the panel is oriented with its face orthogonal to the direction of the sunlight 318. This is because the sensors 302a, 302b are each situated at an equivalent angular displacement to the edge of the collection panel to which each is attached (e.g. 45 degree angles), 318. Thus when the sunlight 318 is striking the face of the panel 100 orthogonally, the sensors on the ends of the panel all have equal angular displacement with respect to the sun's angle of incidence, and thus show roughly equal light intensity readings (e.g. similar levels of resistance in the photoresistor circuit or similar levels of current in the case of a photodiode sensor). Thus the displacement of panel 100 from orthogonal orientation to the sunlight 318 leads to the reading on one sensor 302a, 302b to be greater than that on the other side, and this differential triggers the electromagnets or other actuators to rotate the panel 300 in the direction 312 towards the sensor 302a, 302b with greater luminous intensity until the readings on both sets of sensors are 302a, 302b roughly equal.

While FIGs. 3A-3C illustrate this tracking process in two dimensions only, a three dimensional tracking process may be implemented. FIG. 3A shows the panel turned too far left, thus the light intensity reading on sensor 302b will be greater than on sensor 302a since its orientation towards the sun will be closer to orthogonal, so the electromagnets fire so as to rotate the ball in the direction of sensor 302b as shown. FIG. 3B shows it rotated too far in the other direction, with the reading on sensor 302a greater than that for sensor 302b, so the electromagnets fire to rotate the ball in the direction of sensor 302a.

When deployed with four sensors and the two arrays of electromagnets as in FIG. 1A, the panel can achieve tracking in three dimensions along the sun's azimuth and elevation.

The light sensors in FIG. 1 and FIG. 3 record the intensity of the ambient light and use it to toggle a resistance circuit that controls power to the electromagnets to rotate the ball and panel along the elevation and azimuth of the sun's path.

In the following, suppose for simplicity that the luminous intensity recorded by the sensors were recorded on a unit-less discrete integer scale from 1 to 100, with 1 indicating the lowest luminal intensity and 100 the highest recordable by the sensor. Denote the four sensors depicted in FIG. 1A top view sensors 1, 2, 3, and 4, and denote, e.g., sensor 2 having a value of 39 as sensor[2] = 39. Sensors 1 and 2 are on two opposing edges, e.g., right and left, and sensors 3 and 4 are on the other two opposing edges, e.g. top and bottom. Suppose as well that the electromagnets can pulse at a single discrete energy level in the ways shown FIGs. 2B-2C and 2E-2F, and that the ball is of north polarity. The electromagnet arrays are labeled a, b, c, and d, and can each pulse a burst of north-poled magnetic energy with the side of the magnet facing the ball clockwise from the middle of the magnet array labeled 1, and counterclockwise from the middle labeled 2 (see FIG. 2B). Thus if array a pulsed 1 while array b pulsed 1, the ball would rotate clockwise about axis X (FIG. 2B). Likewise if array a pulsed 2 and array b pulsed 2 it would rotate counter- clockwise about the x-axis. Thus denote clockwise rotation on the x-axis as pulse(a,b) = 1, and counter-clockwise on the x-axis pulse(a,b) = 2. Similarly clockwise rotation on the y- axis is pulse(c,d) = 1 and counter-clockwise is pulse(c,d)=2. No rotation in the x-axis direction is denoted pulse(a,b) = 0 and in the y-axis direction pulse(c,d) = 0, and thus engagement of the stopper mechanism, (see FIG. 3; the x-axis relates to rotation along an axis parallel to the earth's surface, and the y-axis is rotation perpendicular to the horizon line, for example, north and south and east and west). With these assumptions, an example sun-tracking process is as follows in pseudocode. One of ordinary skill in the art will recognize that minor alterations to the pseudocode below may be made without departing from the disclosure. Assume a small tracking error summarized by a "fudge factor" equal to 1 unit of luminal intensity to allow the computer process to terminate. The abs() operator stands for absolute value:

Sun tracking process:

Loop:

if abs(sensor[l] - sensor[2]) > fudge factor {

if sensor[l] > sensor[2] { pulse(a,b) = 2}

else if sensor[l] < sensor[2] { pulse(a,b) = 1 }

}

else{ pulse(a,b) = 0} if abs(sensor[3] - sensor[4]) > fudge factor {

if sensor[3] > sensor[4] { pulse(c,d) = 2}

else if sensor[3] < sensor[4] { pulse(c,d) = 1 }

}

else { pulse(c,d) = 0}

The "loop" elaborated above is executed frequently, e.g. several rapid iterations spaced every few minutes or several times a minute, to achieve sun tracking. Thus e.g. if sensor[l] = 90 and sensor[2] = 30, because, for example, sensor 1 was getting more light than sensor 2, the magnets in arrays a and b would pulse so as to move the ball in the direction of sensor 1. The control process iterates till the reading on sensor 1 roughly equals the reading on sensor 2, and the reading on sensor 3 roughly equals the reading on sensor 4.

To save energy, the above control process could be implemented on a simple electrical circuit, instead of on a computer chip: an additional circuit could be attached to sensors 1 and 2 and sensors 3 and 4 that breaks when they have electrical resistance or current readings that were not extremely close to each other. It could further translate the sign of the differential to fire one set of the electromagnets or another in order to rotate the ball in either direction until the sensors gave roughly equal reading and completed the circuit. In actual implementations, the size of the differential between the sensors could translate to the power of the magnet signal, though discrete, uniform-duration electromagnet pulses when moving the ball are likely more optimal to ensure the ball moves smoothly. Thus the pulses of the electromagnets in the control process above could be of fixed duration and the control process could be executed iteratively until the terminal condition is achieved. The movement pulses could be standardized to a small duration to prevent overshooting of the terminal condition and thus long or infinite looping of the control process.

Solar thermal power solutions have been gaining in attention and popularity in recent years. These systems use concentrated solar radiation to heat a working fluid, or another storage or heat transfer medium that is used to heat a working fluid, used to drive a generator turbine or engine, e.g. a steam engine. Parabolic collectors are often used for this purpose in conjunction with evacuated-tube collectors, and the above system can be used without modification for that purpose, with the parabolic collector sitting exactly where the flat panel 100 is shown in FIG. 1. The same principal of maximizing solar energy collection through solar tracking described above can also be applied to solar thermal energy production with flat collectors that require the light to pass through the focusing surface to a target area beyond: for example, flat Fresnel lenses used in modified solar-voltaic panels can be used on their own for creating high-energy beams of solar radiation to be used in solar thermal power generation. Like other flat solar panels, these lenses collect maximum solar energy when oriented with their faces orthogonal to the direction of the sunlight.

A modification of the design described above could be made to allow solar tracking by Fresnel lenses in a way that allows the energy captured by them to be used for solar thermal purposes, especially in the case where the targeting area of the solar beam must remain in a fixed location. This section describes the alterations to the above design required to achieve this.

For a flat solar-focusing lens such as a Fresnel lens, a hollow ball is used and the ball is altered by cutting a bowl-like depression in one quadrant of the sphere that terminates at a hollow opening at a distance from the center of the ball, on the side that is submerged in the liquid medium (the ball in cross section would look a little like Pacman). The counterweight to the lens must then be a ring around the top of the bowl-like depression's edge. The edge of the ball underneath the Fresnel lens is removed to allow the light to focus through the ball. The ball is hollow, and is of a diameter such that the radius is roughly equal to or greater than the focal length of the Fresnel lens. A converging lens with a ratio of diameter to focal length that is at least as great as that of the Fresnel lens is suspended from the edges of the hollow opening, such that the focusing surface of the lens is a distance away from the focal point of the Fresnel lens equal to the focal length of the converging lens. This converts the light beams diverging away from the Fresnel lenses focal point into a collimated beam.

[0001] This beam is aimed at an opening to a mirrored chamber with slightly concave interior surfaces positioned within the liquid medium; the concavity of the surfaces will lessen the number of points of contact between the beam and the mirrors before the beam reaches the target surface. A straight tube with an interior mirrored surface could also be used. The mirrored chamber's opening proceeds beyond the bottom of the container. At the bottom of this chamber lies an opening that leads to the target surface of the solar collection vessel. This mirrored chamber could lie at the center of the liquid medium such that any radiation not reflected by the concave mirrored surfaces (e.g. infrared) can be used to heat the interior liquid medium for use in pre-heating water or other working fluids for thermal power generation or for generating hot water.

The interface at the center of the ball where the collimated light beam is aimed into the mirrored chamber lies above the surface of the water. Thus the ball is chosen to be of a size and material such that it's density is much less than 50% of that of the same volume of water, to allow this interface to occur in open air and avoid wear-and-tear problems of gaskets under water. To prevent damage to the interface at the center of the ball between the mirrored chamber leading to the target area and the focusing convergent lens, the lip of the barrel-like chamber that holds the liquid medium and floating ball could be smaller than half the ball's diameter such that the converging lens housing and edge of the hollow opening at the center of the ball could not touch the top of the fixed mirrored chamber.

The basic principles of solar tracking by rotating a floating magnetized ball by powering 4 sets of magnets can be used to rotate a ball suspended by 4 ropes. The ropes are attached to pulleys with counter weights and motors to move the ropes. The control process described above would operate in a broadly similar way. The foregoing examples or preferred embodiments are provided for illustration purpose and are not intended to limit the present invention.

Claims

CLAIMS What is claimed is:

1. A solar tracking system comprising: a plurality of light sensors arranged at an angular displacement to a light sensitive upper surface of a solar collecting device fixed on a support structure, and a processor equipped with a software program for translating outputs of the light sensors into activations of actuators to move the light sensitive upper surface of the solar collecting device in response to sun movements through moving the support structure.

2. The solar tracking system of claim 1, wherein the light sensors comprise one or more photo-electric devices that translate(s) luminous intensity into electric current or resistance.

3. The solar tracking system of claim 2, wherein said photo-electric device comprises one or more photoresistors or photo-diode circuits.

4. The solar tracking system of any one of claims 1 to 3, wherein the light sensors are so oriented that each sensor faces at an angle to the side of the face of the solar collection device to which it is attached, with the sensing side facing away from the solar collection device.

5. The solar tracking system of claim 4, wherein said angle is 45-degree or an angular displacement between 0 and 90 degrees that allows appropriate differential readings across the sensors to be captured.

6. The solar tracking system of any one of claims 1 to 5, wherein the light sensors are used to control a computational process through a computer chip or an analog electrical circuit that pulses the electromagnets in order to achieve approximately equal luminous intensity across the sensors.

7. The solar tracking system of any one of claims 1 to 6, wherein the light sensors record the intensity of the ambient light and use it to toggle a resistance circuit that controls power to the actuators for moving the support structure and the solar collection device along the elevation and azimuth of the sun's path.

8. The solar tracking system of any one of claims 1 to 7, comprising four sensors and two arrays of electromagnets so that the solar collection device is capable of achieving tracking in three dimensions along the sun's azimuth and elevation.

9. The solar tracking system of any one of claims 1 to 8, wherein the light sensors are oriented on the solar collection device with one sensor on each of the top and bottom of the solar collection device to control movement in one axis and two sensors on the sides to control the other axis, wherein the combined action of the movement in both axes provides the three dimensional rotation required for sun tracking.

10. The solar tracking system of any one of claims 1 to 9, wherein said actuators comprise a plurality of electromagnets capable of providing an electro-motive force to move the solar collecting device through the support structure.

11. The solar tracking system of any one of claims 1 to 10, wherein said software program comprises a machine readable instruction to control movement of the supporting structure.

12. The solar tracking system of any one of claims 1 to 11, wherein:

the support structure comprises a ball shaped casing having a magnetic or electro- conductive surface;

the actuators comprise a plurality of electromagnets capable of providing an electro-motive force to move the ball shaped casing; and

the software program comprises a non-transitory machine readable memory, wherein the memory comprises program instructions to cause the processor to align the upper light sensitive surface in an optimal position relative to the angle of incidence of incoming sunlight.

13. The solar tracking system of claim 12, comprising:

a plurality of electromagnets capable of providing an electro-motive force to move the ball shaped casing; and

a processor and non-transitory machine readable memory, wherein the memory comprises program instructions to cause the processor to align the upper light sensitive surface in an optimal position relative to the angle of incidence of incoming sunlight through determining the intensity of reading of each of the light sensors relative to each other and firing the electromagnets to cause the ball shaped casing to move so that the intensity of each reading for each of the light sensors is approximately equal.

14. The solar tracking system of claim 13, wherein the light sensors comprise one or more photo-electric devices that translate(s) luminous intensity into electric current or resistance.

15. The solar tracking system of claim 14, wherein said photo-electric device comprises one or more photoresistors or photo-diode circuits.

16. The solar tracking system of any one of claims 13 to 15, wherein the light sensors are so oriented that each sensor faces at an angle to the side of the face of the solar collection device to which it is attached, with the sensing side facing away from the solar collection device.

17. The solar tracking system of claim 16, wherein said angle is 45-degree or an angular displacement between 0 and 90 degrees that allows appropriate differential readings across the sensors to be captured.

18. The solar tracking system of any one of claims 13 to 17, wherein the light sensors are used to control a computational process through a computer chip or an analog electrical circuit that pulses the electromagnets in order to achieve approximately equal luminous intensity across the sensors.

19. The solar tracking system of any one of claims 13 to 18, wherein the light sensors record the intensity of the ambient light and use it to toggle a resistance circuit that controls power to the electromagnets for rotating the ball shaped casing and the solar collection device along the elevation and azimuth of the sun's path.

20. The solar tracking system of any one of claims 13 to 19, comprising four sensors and two arrays of electromagnets so that the solar collection device is capable of achieving tracking in three dimensions along the sun's azimuth and elevation.

21. The solar tracking system of any one of claims 13 to 20, wherein the light sensors are oriented on the solar collection device with one sensor on each of the top and bottom of the solar collection device to control movement in one axis and two sensors on the sides to control the other axis, wherein the combined action of the movement in both axes provides the three dimensional rotation required for sun tracking.

22. The solar tracking system of any one of claims 13 to 21, wherein the ball shaped casing is covered with a weakly magnetic substance or imparted a small electrical charge via an electrode applied to the ball.

23. The solar tracking system of any one of claims 13 to 22, wherein the ball shaped casing is hollow or solid and balanced by a counterweight anchored at the bottom end of the casing.

24. The solar tracking system of any one of claims 13 to 23, wherein the ball shaped casing is made of a conductive material so that the ball is magnetized via a small electric current applied to the liquid medium, and the liquid medium allows the flow of electric current.

25. The solar tracking system of any one of claims 13 to 23, wherein the ball shaped casing is made of metal or plastic.

26. The solar tracking system of any one of claims 13 to 23, wherein the ball shaped casing is of an appropriate size and material relative to density and volume of the liquid medium such that it floats in the liquid medium with half or more of its surface area floating above the surface level of the liquid medium, which allows the light sensitive upper surface of the solar collection device to move nearly 180 degrees in relation to the sun's azimuth and elevation.

27. The solar tracking system of any one of claims 13 to 26, wherein the counterweight has a weight approximately the same as the weight of the solar collection device.

28. The solar tracking system of any one of claims 13 to 27, wherein the counterweight comprises a sealable cavity that can be filled with a variable amount of the liquid medium or a heavier liquid medium to achieve a desired counterweight.

29. The solar tracking system of any one of claims 13 to 28, wherein the ball- shaped casing is moved by the electromagnets firing at the exterior surface of the ball, in order to minimize frictional, inertial and gravitational resistance in moving the panel.

30. The solar tracking system of any one of claims 13 to 29, wherein the rotation of the ball-shaped casing is controlled by a control process that converts the inputs of four photoresistors or other luminous intensity-sensing circuits into short magnetic pulses.

31. The solar tracking system of claim 30, wherein the four photoresistors or other luminous intensity-sensing circuits are located on the edges of the solar collection device at a consistent angular displacement to the portion of the device's face to which they are attached.

32. The solar tracking system of any one of claims 13 to 31, wherein said plurality of electromagnets comprises four electromagnets, each fixed on one side of the container.

33. The solar tracking system of claim 32, wherein the four electromagnets are situated on the four sides of the ball shaped casing in substantially the same horizontal plane.

34. The solar tracking system of any one of claims 13 to 33, wherein the plurality of electromagnets rotate the ball about its center by applying a substantially equivalent same-pole force (repellant magnetic force) or opposite-pole force to the ball at points just off of center from each other on either side.

35. The solar tracking system of claim 34, wherein two of these electromagnets rotate the ball horizontally with respect to the earth's surface, and the other two rotate it vertically and substantially perpendicular to the horizon line, and the combined action rotates the panel surface in relation to the sun's elevation and azimuth.

36. The solar tracking system of any one of claims 13 to 35, wherein the container is barrel-like or bowl-like, having an edge of the mouth of the barrel or bowl almost touching the ball shaped casing.

37. The solar tracking system of any one of claims 13 to 36, further comprising a plurality of stoppers or tension mechanisms to hold the ball in place so that the ball does not move unless acted on by outside forces.

38. The solar tracking system of claim 37, wherein said plurality is four and each of the four stoppers or tension mechanisms is on one of the four sides of the ball shaped casing in a plane parallel to the ground,

39. The solar tracking system of claim 37 or 38, wherein the edges of the solar collection device protrude beyond the diameter of the opening of the container, or the stoppers protrude from the surface of the ball so that the solar collection device is prevented from moving beyond this range into the liquid medium.

40. The solar tracking system of any one of claims 37 to 39, wherein the tension mechanism is aligned with the electromagnets to apply friction or mechanical force to the edges of the ball shaped casing to absorb the angular momentum imparted by these forces and thus hold the ball in place when the electromagnets are not firing.

41. The solar tracking system of any one of claims 37 to 40, wherein the tension mechanism also serves to stop the ball's rotation after it is rotated by the force of the electromagnets.

42. The solar tracking system of any one of claims 37 to 41, wherein the tension mechanism comprises a device selected from the group consisting of spring assemblies, ball-and-socket joints, and spring-loaded rubber pads, which applies a friction and/or mechanical force to the edges of the ball in order to hold it in place and/or to stop its rotation after the electromagnets stop firing.

43. The solar tracking system of claim 42, wherein said device of the tension mechanism remains in continuous contact with the ball shaped casing if the force exerted by the electromagnets on the ball is greater than the force of the tension mechanism on the ball; or alternatively, the tension mechanism is capable of removing or decreasing the tension exerted on the ball at the exact time when the electromagnets fire to move the ball.

44. The solar tracking system of any one of claims 37 to 43, wherein opposite pole of the electromagnets is oriented to pull a piece of metal connected through a small gear to the back of the tension mechanism on a spring-loaded plunger, so that when the electromagnets fire to move the ball, they simultaneously release the tension mechanism, and when the electromagnets stop firing the spring, they reengage the stopper of the tension mechanism.

45. The solar tracking system of any one of claims 37 to 44, wherein the surface of the ball shaped casing is covered in small grooves to allow the tension mechanism to move pins that lock the ball in place.

46. The solar tracking system of any one of claims 13 to 45, wherein the electromagnets are connected via a circuit to the light sensors oriented approximately at mid-points of the four edges of the solar collection device.

47. The solar tracking system of any one of claims 1 to 46, wherein the liquid medium has a density substantially same as or greater than the density of the ball shaped casing so that the ball shaped casing floats in the liquid medium and is capable of movement with little or no friction between the ball shaped casing and the container.

48. The solar tracking system of any one of claims 1 to 47, wherein the liquid medium is water or another low-viscosity liquid.

49. The solar tracking system of any one of claims 1 to 48, wherein the edges of the solar collection device protrude from the edge of the ball shaped casing, or alternatively, the solar collection device is embedded in the ball shaped casing.

50. A solar energy collection system comprising a solar tracking system according to any one of claims 1-49.

51. The solar energy collection system of claim 50, wherein the solar collection device is a flat panel collector or a parabolic trough collector.