Solar array tracker controller   

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to solar array tracker controllers, more particularly to a solar array tracker controller which utilizes inputs of the local latitude, longitude, universal time and software incorporating a mathematical algorithm that calculates the optimal positioning of the solar array and initiate movements to achieve the optimal positioning.

2. Background Art

Automated solar tracker controllers are widely used to optimize positioning of solar panels. Solar energy collectors perform most efficiently when the incident rays of the sun are perpendicular to the absorbing surface. And because the position of the sun is constantly changing in relationship to the earth, it is necessary to continually reposition the absorbing surface of solar panels to maintain the most advantageous, perpendicular angle of incidence to the sun\'s rays. Various solar collector drive mechanisms and tracker controls have been devised for maintaining this optimal angle. The following are exemplary, though by no means exhaustive.

U.S. Pat. No. 4,175,391 to Baer, describes apparatus for causing a solar energy collector to follow the sun by using solar radiant energy to differentially heat fluid-containing reservoirs to cause differential vaporization and shifting of fluid to rotate the apparatus. Automatic morning orientation is included by providing the easterly reservoir with a faster rate of cooling than the westerly one, thereby causing shift of fluid from westerly to easterly after sunset resulting inclination toward the east by sunrise.

U.S. Pat. No. 4,104,521 to Winders, teaches a high angular accuracy sensor and tracking device utilizing a symmetrical sensor shade and sensor arrangement. The apparatus utilizes a circuit control for the electric motor drive of the tracker.

U.S. Pat. No. 4,215,521 to Weslow, et al., discloses an open loop servo controller for motors driving solar panels about its azimuth and altitude axis to track the sun. The controller has a central processing unit and a user interface for inputting data relating to the present day, hour, minute, and the latitude and longitude of the installed device. Program data and tables of data corresponding to the declinations of the sun on any day, and other mathematical functions are stored in memory. The processor utilizes the data to calculate the azimuth and altitude of the sun for every minute of the day and issues control signals that cause motors to move the device to the calculated angles.

U.S. Pat. No. 4,469,899 to Moore, describes an apparatus for tracking the motion of the sun utilizing a plurality of solar cells that generate electric signals when exposed to solar radiation. The solar cells are mounted in trough-like shadow boxes which permit exposure of the solar cells to solar radiation only at predetermined angles. The shadow boxes are mounted for concomitant rotation around a vertical and horizontal axis and are driven by a pair of motors. The motors are controlled by the output of the solar cells and reposition the shadow boxes to shade the solar cells responsive to the motion of the sun.

While the above-described patents are each directed to apparatus for solar tracking and describe devices that initiate movement of solar energy utilizing devices, none describe a system incorporating a GPS interface that instantly and constantly updates the location and time of the solar panel system and thereby situates the system relative to the sun according to the date and time. Additionally, none describe a remote interface to the Internet for remote access to the controlling device. The present invention, as described and claimed herein, provides such features, as well as several other advantages and improvements over the prior art.

The foregoing patents reflect the current state of the art of which the present inventors are aware. Reference to, and discussion of, these patents is intended to aid in discharging Applicants\' acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated patents disclose, teach, suggest, show, or otherwise render obvious, either singly or when considered in combination, the invention described and claimed herein.

The present invention is a solar array tracker controller that utilizes inputs relating to local latitude, longitude, and universal time, and then based on the inputs employs a mathematical algorithm to calculate the optimal positioning of the solar array and to initiate movement of solar collectors to achieve the optimal positioning. While suitable for use with even a single photovoltaic or solar collector panel, the tracker controller of the present invention is particularly well suited for controlling the positioning of large arrays of solar panels deployed in, and mounted on, support structure such as that described in co-pending International Patent Application Serial Number PCT/US06/38185, filed 28 Sep. 2006 (28 Sep. 2006), and entitled Solar Panel Array Sun Tracking System, which application is incorporated in its entirety by reference herein. Such arrays and array tracking apparatus include panel support structure operatively connected to drive motors that mechanically pivot and rotate entire rows and columns of panels in an array simultaneously and in complete coordination in either or both east/west and/or north/south axes, as called for by the installation. The tracker controller of the present invention is designed to provide motor control inputs that optimally position the panels in an array.

The solar array tracker controller of the present invention utilizes a processor programmed with the above-described algorithm for accurately predicting the location of the sun based on the date, time of day in hours and minutes, local latitude and local longitude. The program takes into account the elliptical orbit of the earth around the sun, which changes slightly over time.

The controller also includes an interface for a Global Positioning Sensor (GPS) that provides highly accurate information on latitude, longitude and global time to the processor. Additionally, the processor has a digital interface for a highly precise inclinometer. The inclinometer is mounted along the rotational axes of the solar energy utilizing device such as a solar panel array. The inclinometer relays the angle of the solar panels on the tracker through the digital interface to the processor. The processor then utilizes the information from the inclinometer to send optimized positioning information to one or more drive and adjustment motors, which adjust the position of the solar array to optimize the angle of incidence to solar rays. Back and forth east/west movement of the panels is accomplished by moving the motors forward and backward. The combination of east/west travel, azimuth and angle of altitude calculated and positioned by the processor, create an optimized angle of incidence for the solar energy utilizing device to solar rays.

As noted, the processor includes networking capability and Ethernet or Internet capability, and further includes a remote interface that allows remote acquisition of data and status of the apparatus on a local area network, a wide area network, or global network.

The tracker includes a stand-alone wind sensor and an AC converter that digitizes wind measurements for input of the sensor signals to the processor. This weather information is utilized in severe conditions only, to move the tracker into a neutral aerodynamic stow position (generally horizontal) at times of high winds.

Other novel features which are characteristic of the invention, as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing, in which preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawing is for illustration and description only and is not intended as a definition of the limits of the invention. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. The invention resides not in any one of these features taken alone, but rather in the particular combination of all of its structures for the functions specified.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a block diagrammatic representation of the solar array tracker controller of the present invention.

100 solar array tracker controller

110 processor / micro-controller

120 operator interface

140 GPS interface

145 Global Positioning Sensor (GPS)

150 digital interface

160 inclinometer

170 solar energy utilizing device

190 initiating relays

205 motor

210 jack screw or drive shaft

220 remote interface

230 Internet

240 wind sensor

Referring to FIG. 1, wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved solar array tracker controller, generally denominated 100 herein.

FIG. 1 illustrates a preferred embodiment of the solar array tracker controller 100, and shows that the system comprises a micro-processor/controller 110 having an integral operator interface 120 with an LCD display and a keypad for entry of local data. An exemplary system is the Z-World OP6800, which is a relatively low-cost, C-programmable operator interface and single-board computer with industrialized I/O, a graphic LCD, and a keypad. It includes an integrated control, display, and networking capabilities via Internet/Ethernet or serial communications. This processor includes memory for storing a program including a mathematical algorithm that accurately determines the location of the sun based on local data, such as the date, time of day in hours and minutes, local latitude and local longitude. The algorithm takes into account the elliptical orbit of the earth around the sun which changes slightly over time.

The processor 110 also includes a GPS interface 140 for a Global Positioning Sensor (GPS) 145 which provides highly accurate information on latitude, longitude and global time to the processor. Additionally, the processor has a digital interface 150 for a tilt sensor or inclinometer 160, such as the Model SCA100T inclinometer made by VTI Technologies of Vantaa, Finland, or the Model 0717-4304-99 TrueTilt, dual axis, wide angle, electrolytic tilt sensor made by The Frederick\'s Company of Huntingdon Valley, Pa. The inclinometer 160 is mounted along one or more axes of a solar energy utilizing device 170, such as a solar panel in a solar panel array. The inclinometer 160 relays to the processor data concerning the angle of altitude and azimuth of the solar energy utilizing device 170 through the digital interface 160 on the processor. The processor then utilizes the information from the inclinometer to send optimized positioning information to one or more drive motors 205, which are operatively linked or connected to pivoting and rotating apparatus which adjust the position of the solar energy utilizing device (panels) 170 to optimize the angle of incidence to solar rays.

The processor also controls the east/west orientation of the solar energy utilizing device 170 by initiating relays 190 to the drive motors 205 to actuate forward and reverse movement of drive apparatus 210, such as a jack screw or a reciprocating drift shaft. The combination of east/west travel, azimuth, and angle of altitude calculated and positioned by the processor creates an optimized angle of incidence for the solar energy utilizing device to solar rays.

The processor also has a remote interface 220 that allows remote acquisition and transmission of data and status of the via a global computer network, such as the Internet 230, or in a wide area network or local area network.

Further, the tracker controller includes a stand alone wind sensor 240 which digitizes the wind sensor signals for input into the processor. In times of potentially damaging high winds, the signal alerts the processor to send control inputs to the drive motors to position the array panels in a substantially neutral aerodynamic stow position (i.e., generally horizontal) This weather information is utilized to move the tracker into a horizontal stow position in times of high wind conditions.

Accordingly, it will be appreciated by those with skill in the art that the solar panel array tracker controller of the present invention, in its most essential aspect, comprises a micro-processor coupled to the drive motors of a solar panel array. The processor is programmed to calculate the precise location of the sun relative to the array, and then to control the motors based on local data, either input by an operator or by a GPS sensor connected to the processor to place the array panels in an optimal angle of incidence in relation to the sun\'s rays. One or more tilt sensors or inclinometers mounted on a panel or panels provide information to the processor concerning the current configuration of the array.

The foregoing disclosure is sufficient to enable those with skill in the relevant art to practice the invention without undue experimentation. The disclosure further provides the best mode of practicing the invention now contemplated by the inventor.

While the particular solar tracker array controller apparatus and method herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages stated herein, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended concerning the detail of construction or design shown other than as defined in the appended claims. Accordingly, the proper scope of the present invention should be determined only by the broadest interpretation of the appended claims so as to encompass obvious modifications as well as all relationships equivalent to those illustrated in the drawings and described in the specification.