US20100139645A1

US20100139645A1 - Balanced support and solar tracking system for panels of photovoltaic cells

Info

Publication number: US20100139645A1
Application number: US12/592,480
Authority: US
Inventors: Gerald Whipple; Tom Willsey; Spencer Murphy; Sterling Holmes
Original assignee: SUN A RAY LLC
Current assignee: SUN-A-RAY LLC; SUN A RAY LLC
Priority date: 2008-12-01
Filing date: 2009-11-25
Publication date: 2010-06-10

Abstract

A solar tracking mechanism and mounting platform for solar panels is mounted with three or four legs attachable to a concrete pad and includes a substantially vertically disposed axle and a substantially horizontally disposed axle to which a plurality of panel support members are mounted to form a panel support assembly. The vertically disposed axle allows at least 240 degree rotation of the panel support assembly to follow the daily East-West travel of the Sun in the sky. The substantially horizontally disposed axle allows declining or tilting of the panel support assembly for the North-South adjustment of the panel support assembly to correspond to the geographic latitude of the location where the solar tracking mechanism and platform is used. The substantially horizontally disposed axle is placed on the centroid or substantially on the centroid location relative to the panel support members, including solar panels so that, as a result, the assembly is completely or substantially balanced and can be placed horizontally or in any inclined position without the weight of the assembly, including solar panels mounted thereon, causing it to precipitously drop or fall.

Description

CLAIM OF PRIORITY OF PROVISIONAL APPLICATION

The applicants claims priority of provisional application Ser. No. 61/200,550, filed on Dec. 1, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention is in the field of support and tracking systems for an array of photovoltaic cells. More particularly, the present invention relates to a support and tracking system for an array of photovoltaic cells that is well balanced in the North-South declination sense and has numerous additional improvements over the state-of-the-art.
2. Brief Description of the Prior Art
The need to obtain reliable and renewable energy sources alternative to fossil fuels is greater at the present time than perhaps in any previous time in history. Electrical power generated from solar irradiation is a well known alternative and renewable energy source and the technology to exploit this source has been advancing rapidly during the last few decades. In the present state of the art photovoltaic cells are available that are capable of supplying very substantial electrical energy. Because photovoltaic cells are typically arranged in substantially flat panels, the terms “photovoltaic cells” and “solar panels” can be used interchangeably for the purposes of describing the state-of-the-art pertinent to the present invention, and for describing the invention itself.
Photovoltaic cells or solar panels are typically permanently mounted on flat surfaces such as roofs, or on stands, poles, frames or other mounting apparatus or mechanism. It is well known in the art, that better performance is obtained from solar panels when the panels continuously face the sun, that is, when they follow the Sun on its East to West daily track in the sky. This type of movement of the panels is commonly known as East-West movement or adjustment. It is also known in the art that still further improved performance is obtained from solar panels if the panels are inclined or tilted relative to the horizontal as a function of the geographical latitude of the location where the panels are, and still further if periodic adjustment of the panels' inclination or tilt is made during the seasons when the position of the Sun in the sky changes. This type of adjustment of the position of the solar panels is referred to as a North-South adjustment.
Photoelectric devices and associated electronic circuitry are available in the state-of-the-art to detect the position of the Sun in the sky and to control an electric motor or like device to cause the panels to move East-West to follow the daily track of the Sun in the sky, provided the mounting apparatus or mechanism allows such movement.
When the mounting apparatus allows adjustment of the North-South inclination or tilt of the panels, then this is typically performed periodically, but not necessarily daily, as the seasons change. A good practical rule to be followed in this regard is that during the summer the panels should be declined relative to the horizontal at an angle that is approximately 15 degrees less than the latitude-in-degrees of the location where the panels are, and during winter at an angle of 15 degrees greater than the latitude-in-degrees of the location where the panels are. Optimally, the declination of the panels can also be periodically changed between the above-noted two extremes as the seasons change.
The solar panels have substantial weight and because they are typically arranged in arrays of multiple panels, their combined weight can amount to several hundred or with wind loads to even several thousand pounds. It should already be apparent from the foregoing that the mounting mechanism that is capable of supporting this much weight and is also capable of reliably allowing the North-South adjustment of panels and reliably performing or allowing the East-West daily movement of the panels is relatively complex itself. In fact, the prior art has produced a large number of such mounting and tracking mechanisms as evidenced by the numerous United States and foreign patents, published patent applications and catalogs and advertisements in this field of technology.
More specifically, such mounting devices or mechanisms are described, for example, in U.S. Pat. Nos. 6,046,400; 4,280,853; 4,457,297; 6,563,040; 6,848,442; 6,302,099; 6,239,353; 7,240,674; 7,202,457; 4,225,781; 4,266,530; 4,302,710; 4,476,854; 4,202,321; 6,248,968; and in 4,172,739; in Published Patent Applications Nos. US 2004/0238025; US 2007/0227574; EP 1 241 416 A2; WO 92/11496; and WO 2005/026628.
Additional disclosures of interest to the present invention and pertaining to mounting mechanisms of various devices such as panels, solar cameras, weathering test apparatus and the like are found in U.S. Pat. Nos. 3,889,531; 70,09; 931,692; 6,572,061; 6,305,653; 4,378,100; 6,766,623; and 6,563,040.
In spite of the relatively large number of such disclosures of mounting and tracking apparatus for solar panels the mounting apparatus known in the present state-of-the-art still have some serious disadvantages in terms of the cost of installing them to a permanent location, their durability, particularly the durability of their East-West tracking and North-South tilting mechanism, and their ability to withstand wind pressures which can be very substantial. The present invention provides improvements in terms of all these problems of the prior art.
Another serious problem in the prior art relates to the weight of the solar panels when a North-South declination or tilting is adjusted or maintained. More specifically, whenever North-South declination or tilting and its periodic adjustment are enabled, the array of panels is mounted on an axis that allows such tilting relative to the horizontal. In all prior art mounting apparatus known to the present inventors whenever such North South tilting is enabled, the weight of the panels would normally cause the array to precipitously drop or fall relative to the horizontal axis until the maximum angle allowed is reached. This uncontrolled drop or can seriously injure or even kill a person who may be hit by the combined weight of the panels and the may damage the entire mounting device and the panels themselves. The state-of-the-art is aware that seriousness of this problem increases with the size and therefore with the weight of the array of panels. Because such rapid uncontrolled drop of the array of panels must be prevented to avoid injury and damage in the present state-of-the art usually at least two persons are needed to install the solar tracking apparatus. Usually two persons are needed also when the periodic adjustment of the North-South declination is performed. Even then, the installing persons are not free of danger, and sometimes other mechanical assistance is needed to avoid the damage or injury. One principal feature of the present invention is to eliminate the just-described serious problem.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a solar tracking mechanism and mounting platform that can be installed on a concrete foundation instead of attached to a pole affixed in the ground.
It is another object of the present invention to provide a solar tracking mechanism and mounting platform having an array of panels that is less subject to wind pressure than similar size panels mounted in accordance with the prior art.
It is still another object of the present invention to provide a solar tracking mechanism and mounting platform that has long useful life and requires a minimum of repairs or maintenance procedures.
It is a further advantage of the present invention to provide a solar tracking mechanism and mounting platform that is completely or substantially completely balanced relative to a horizontal axis of declination or tilting whereby the danger of damage and injury to persons is eliminated or minimized during installation and during adjustment of the North-South declination of panels.
These and other objects and advantages are attained by a solar tracking mechanism and mounting platform for solar panels that is mounted with three or four legs attachable to a concrete pad and includes a substantially vertically disposed axle and a substantially horizontally disposed axle to which a plurality of panel support members are mounted to form a panel support assembly. The vertically disposed axle allows at least approximately 240 degree rotation of the panel support assembly to follow the daily East-West travel of the Sun in the sky. The substantially horizontally disposed axle allows declining or tilting of the panel support assembly for the North-South adjustment of the panel support assembly to correspond to the geographic latitude of the location where the solar tracking mechanism and platform is used.
The substantially horizontally disposed axle is placed on the centroid or substantially on the centroid location relative to the panel support members, including solar panels so that, as a result, the assembly is completely or substantially balanced and can be placed horizontally or in any inclined position without the weight of the assembly, including solar panels mounted thereon, causing it to precipitously drop or fall.
The objects and features of the present invention are set forth with particularity in the appended claims. The invention may be best understood by reference to the following description, taken in connection with the accompanying drawings wherein like numerals indicate like parts.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a perspective view of a preferred embodiment of the solar tracking assembly and mounting platform for solar panels.

FIG. 2 is a partial front view showing an actuator that can be used to adjust the declination or tilt of the panel support assembly and mounted solar panels for North-South adjustment and a motor that allows the rotation of the panel support assembly and mounted solar panels for East-West tracking of the Sun's daily travel in the sky.

FIG. 3 is a cross-sectional view of the motor and gear taken on

lines

3,3 of FIG. 2.

FIG. 4 is a partial side view showing the actuator and the pivot axle for declination or tilting.

FIG. 5 is a cross-sectional view taken on

line

5,5 of FIG. 2.

FIG. 6 is a cross-sectional view taken on

line

6,6 of FIG. 5.

FIG. 7 is a cross-sectional view taken similar to FIG. 5 but showing adjustable rollers.

FIG. 8 is a cross-sectional view taken on

line

8,8 of FIG. 7.

FIG. 9 is a cross-sectional view taken on

line

9,9 of FIG. 8.

FIG. 10 is a top plan view taken on

line

10,10 of FIG. 1.

FIG. 11 is a cross-sectional view taken on line 11 of FIG. 10.

FIG. 12 is a partial front view of a preferred embodiment that lacks a motor and is manually rotatable in the East-West direction.

FIG. 13 is a cross-sectional view taken on

line

13,13 of FIG. 12.

FIG. 14 is a partial side view of a preferred embodiment that lacks an actuator and can be tilted manually to adjust for Nort-South location and season.

FIG. 15 is a side view taken on

line

15,15 of FIG. 1.

FIG. 16 is a top plan view taken on

lines

16,16 of FIG. 15.

FIG. 17 is a cross-sectional view of taken on

line

17,17 of FIG. 16.

FIG. 18 is a cross-sectional view of taken on

line

18,18 of FIG. 16.

FIG. 19 is a partial top plan view of the solar tracking assembly and mounting platform with solar panels mounted thereon.

FIG. 20 is a cross-sectional view of taken on

line

20,20 of FIG. 19.

FIG. 21 is a view in elevation, taken on

lines

21,21 of FIG. 19.

FIG. 22 is a view in elevation taken on

line

22,22 of FIG. 19.

FIG. 23 is a diagrammatic view of the pivot axle that allows balanced positioning of the panel support members, including the solar panels.

FIG. 24 is a diagrammatic side view of solar tracking assembly and mounting platform with 30 solar panels mounted thereon.

FIG. 25 is a diagrammatic side view of solar tracking assembly and mounting platform showing maximum North-South declination and ground clearance.

FIG. 26 is a perspective view of the presently most preferred embodiment of the solar tracking assembly and mounting platform for solar panels.

FIG. 27 is a partial front view analogous to the partial front view of FIG. 2, thus showing a motor that can be used to adjust the declination or tilt of the panel support assembly and mounted solar panels for North-South adjustment and a motor that allows the rotation of the panel support assembly and mounted solar panels for East-West tracking of the Sun's daily travel in the sky.

FIG. 28 is a cross-sectional view taken on

lines

28,28 of FIG. 27.

FIG. 29 is a cross-sectional view taken on

lines

29,29 of FIG. 28.

FIG. 30 is a cross-sectional view taken on

lines

30,30 of FIG. 29.

FIG. 31 is a partial side view taken on

lines

31,31 of FIG. 27.

DETAILED DESCRIPTION OF THE INVENTION

Preferred Embodiments

The following specification, taken in conjunction with the drawings, sets forth the preferred embodiments of the present invention. The embodiments of the invention disclosed herein are the best modes contemplated by the inventors for carrying out their invention in a commercial environment, although it should be understood that various modifications can be accomplished within the parameters of the present invention.
A perspective view of a preferred embodiment of the solar tracking assembly and mounting platform 40 is provided in FIG. 1 of the attached drawings. For the sake of brevity the solar tracking and mounting assembly may also be referred to simply as the “mounting apparatus”, “mounting platform”, “solar tracking apparatus” or the like. The first described two preferred embodiments have substantially the same construction with the difference being primarily that the first preferred embodiment includes equipment for automatically following the daily track of the Sun in the sky, and an actuator that allows the periodic North-South adjustment of the array of solar panels without using human muscle power. The second preferred embodiment lacks the automatic East-West tracking apparatus, however still enables the at least approximately 240 degrees East West tracking of the Sun by manual power, and also the periodic adjustment of North-South inclination of the panels, by manual power also. The presently most preferred embodiment is described last. This embodiment also includes equipment for automatically following the daily track of the Sun in the sky, and a motor that allows the periodic North-South adjustment of the array of solar panels without using human muscle power, and has additional useful features.
It should be noted at the outset that photosensor apparatus and associated electronic or electric circuitry, electric motors capable of performing the East-West tracking of the Sun when controlled by the photosensor apparatus and electrically powered actuators per se are well known in the art, are commercially available, and need not be described here further.
Referring still primarily to FIG. 1, the solar tracking assembly and mounting platform 40 includes four legs 42 which are preferably placed on and attached to a concrete pad 44. A concrete pad adequate to support the solar tracking assembly and mounting platform 40 together with a plurality of solar panels mounted thereon is typically four (4) inches thick. This arrangement of placing the solar tracking apparatus 40 to a fixed location with four legs 42, or with three legs as in the last described preferred embodiment, is itself a novel and advantageous feature of the present invention. This is because, unless mounted on a flat surface such as a roof, tracking apparatus and solar panels in the prior art are normally mounted on a pole (not shown) that must be deeply embedded in a concrete reinforced hole in the ground. Providing a typically four (4) inches thick concrete pad 44 and attaching each of the legs 42 to the concrete pad 44 is considered less time consuming, less costly and gives better attachment than the previously used mounting poles (not shown). FIGS. 10 and 11 show attachment of the legs 42 in detail. Each of the legs 42 include a flat plate like member 46 that is attached by a plurality of bolts 48 to the concrete pad 44. FIG. 11 also shows the ground 50.
Before describing several of the principal novel features of the present invention the solar panel mounting subassembly 52 of the solar tacking apparatus is described briefly. This description is provided for the purpose of providing a complete description and enabling disclosure and in order to be able to refer to and identify certain components of the subassembly 52 when novel features of the invention are described. The solar panel mounting subassembly 52 is shown in perspective view in FIG. 1. It includes two long main support members 54 and 56 made of steel, aluminum or other strong material capable of supporting substantial weight. The two main support members 54 and 56 are shown substantially horizontally disposed in FIG. 1. The two main support members 54 and 56 are interconnected by a plurality of main cross-support members. The herein described preferred embodiment has four (4) main cross support members 58, 60, 62 and 64. The main support members 54 and 56 and the main cross support members 58, 60, 62 and 64 are affixed to each other by welding or equivalent mechanical means.
Referring still primarily to FIG. 1, a plurality of solar panel support members (shown on FIG. 19) are to be attached on top of the interconnected main support members 54 and 56 and the main cross support members 58, 60, 62 and 64. The presently preferred embodiment of the invention includes up to eight (8) solar panel support members, the two lateral ones of these bear the reference numerals 66 and 68.
Continuing to describe the solar panel mounting subassembly 52, primary reference is made to FIGS. 15 through 18. These drawing figures disclose in detail how the solar panel support members such as 66 and 68 are affixed to the interconnected main support members 54 and 56 and main cross support members 58, 60, 62 and 64. The solar panel support members, such as 66 and 68, are usually not affixed by welding to the interconnected main support members 54 and 56 and main cross support members 58, 60, 62 and 64 because the number of solar panel support members depends on the number of solar panels that are ultimately affixed to and carried by the solar panel mounting subassembly 52. Thus, a spacer 70, a fastening plate 72 and a plurality of carriage bolts 74 and nuts 76 are used to removably but nevertheless strongly affix the solar panel support members to the interconnected main support members 54 and 56 and main cross support members 58, 60, 62 and 64, as is best shown in the cross-sectional views of FIGS. 17 and 18.
FIG. 19 is a partial top plan view of solar panels 78 that are mounted on the above-described solar panel mounting subassembly 52. As is noted before, solar panels per se are well known in the art and are commercially available. They usually come in the size of 3 feet by 5 feet. Such typical size panel usually weighs 35 lbs. Its maximum output of electricity when receiving sunlight varies between 165 and 186 watts, depending on the manufacture and model. It is well known that the maximum possible output of electricity has rapidly grown in the recent past with improved design and manufacturing technology.
The cross-sectional view of FIG. 20 discloses in detail the manner of affixing solar panels 78 to the underlying solar panel mounting subassembly 52 in locations where solar panels 78 abut each other and are not on the edge of the solar panel mounting subassembly 52. This is shown in FIG. 19 where the cross-section of FIG. 20 is taken. A plurality of carriage bolts 80, plates 82 and a plurality of nuts 84 are provided for this purpose. FIG. 20 show attachment of two solar panels to the solar panel support member 66.
FIG. 22 discloses in detail the manner of affixing solar panels 78 to the underlying solar panel mounting subassembly 52 in locations where solar panels 78 abut each other and are in the corner of the solar panel mounting subassembly 52. A plurality of carriage bolts 80, a plate 86 and a plurality of nuts 84, an additional top plate 88 and a spacer bolt 90 are used here as shown in the drawing figure.
It should be readily apparent to those skilled in the art that numerous modifications can be made to the above described solar panel mounting subassembly 52 in terms of the number of main support members, such as 54 and 56, in terms of the number of main cross support members 58, 60, 62 and 64, in the manner of affixing these to one another, and further in the manner of affixing the solar panels 78 to the subassembly 52. Such modifications in terms of the number of the respective support members and the mechanical means, including welding, using nuts, bolts, carriage bolts or like means should be considered equivalent to the above described presently preferred construction and structure of the solar panel mounting subassembly 52 and of the attachment of the solar panels 78 to it.
Having described the solar panel mounting subassembly 52 to which the plurality of solar panels 78 are mounted, reference is now made primarily to FIGS. 2 through 14 together with the perspective view of FIG. 1, where several novel aspects and features of the present invention are disclosed. The solar tracking assembly and mounting platform 40 includes a substantially vertically disposed axle 92 enclosed in an axle housing 94 that forms the basis of East-West rotation of the solar panel mounting subassembly 52 and of the solar panels 78 mounted thereon.
As is shown in FIG. 8, the axle housing 94 terminates on its bottom in a plate 96 that closes the housing and is welded to it. The part shown by reference numeral 98 is a leg stop plate also shown in FIG. 5. A bearing housing or hub 102 is mounted to the plate 96 with bolts 104 and nuts 106. The bearing housing or hub 102 includes tapered bearings 108 into which the vertical axle 92 is mounted. More specifically described in detail, the vertical axle 92 itself terminates in a block 110 that continues in a pin 112 that is mounted in the tapered bearings 108. A nut 114 is placed on the threaded end of the pin 112 to keep the assembly in place. A significant advantage of the just described placement of the vertical axle 92 into the bearing housing or hub 102 is that the assembly can be readily removed for maintenance or repair.
Referring still primarily to FIG. 8, the vertical axle 92 continues upward as a hollow cylindrical member and is further supported by four bearings 116 all four of which, or at least two of which, are adjustable. The vertical axle 92 and the adjustable bearings 116 are also shown in detail in the cross-sectional views of FIGS. 7 and 9. A bearing housing 118 is attached to the axle housing 94 and a pin 120 is held therein to provide the axis of rotation of each bearing 116. Bolts 121 are provided in threaded openings and abut the pin 120 and can move the pin 120 closer to or further away from the vertical axle 92 to provide optimal conditions and support for its rotation. The just described assembly of the adjustable bearings 116 is an advantageous feature of the present invention because it stabilizes the vertical axle 92, and enables it to resist bending under substantial wind pressures that occur frequently when the solar panels 78 are mounted on the tracking apparatus 40. Thus, this feature prolongs the useful life of the apparatus 40. FIGS. 5 and 6 show similar structures but without the bearings being adjustable.
FIGS. 2 through 6 in conjunction with FIG. 1 and the rest of the drawings, as applicable, further disclose the preferred embodiment where the daily East-West tracking of the Sun is performed by an electric motor 122 controlled by a photosensor 124 that is shown only in FIG. 1. The electric motor 122 and photosensor 124 are commercially available. In this embodiment, a housing 126 for the electric motor 122 and other parts (to be described immediately below) is mounted to the legs 42 and encloses non-adjustable bearings 128 for the vertical axle 92. The cross-sectional view of FIG. 5 shows all four of the non-adjustable bearings 128. Each of the non-adjustable bearings 128 is fixedly mounted to the axle housing 94 and rotates on a fixedly mounted pin 130.
The vertical axle 92 has a fixedly attached gear 132 with cogwheel type teeth 136 on its periphery that is in meshing engagement with an output gear 138 of the electric motor 122. The housing 126 is mounted to the legs 42 with plates 140 and bolts 142, as is best shown in FIG. 2. It should be readily apparent from the foregoing description that the electric motor 122 controlled by the photosensor 124 causes slow rotation of the solar panel mounting subassembly 52 together with the solar panels 78 to follow the daily East to West track of the Sun in the sky. Sometime between sunset and sunrise the motor 122 causes the solar panel mounting subassembly 52 and the solar panels 78 to rotate back again to the most eastwardly position. To accomplish this the gear 132 has the cogwheel type teeth 136 on at least approximately 240, preferably on approximately 270 degrees around its periphery. Optionally the gear 132 may be teethed on its entire periphery.
In the just described preferred embodiment a battery 144 is mounted to the legs 42 and provides or contributes to the electric power needed to rotate the solar panel mounting subassembly 52 with the solar panels 78. The battery 144 is shown only in FIG. 1. The battery 144 is charged by the solar panels 78 or may be charged from inside the facility (not shown) to where the solar panels' 78 power is sent. The battery 144 is an optional feature of the present invention because the power to rotate the solar panel mounting subassembly 52 with the solar panels 78 may be provided from another power source, as noted above.
FIGS. 2 and 4 show in detail the construction of the just-described preferred embodiment that also includes the ability to incline the solar panel mounting subassembly 52 together with the solar panels 78 to adjust for the geographic latitude of the location where the tracking apparatus 40 is used, and further to periodically adjust for the change of the position of the Sun in the sky due to change of seasons. Thus, the solar panel mounting subassembly 52 is mounted on a substantially horizontally disposed axle 146. The herein described preferred embodiment has the axle 146 in two parts 146 a and 146 b as is best shown in FIG. 2. Having the axle 146 in two parts provides an advantage in construction, maintenance and when repair is needed. The detailed drawing of FIG. 2 discloses a member 148 (also shown in FIG. 1) that is fixedly attached to the upper end of the vertical axle 92. Plates 150 are mounted to project upwardly from the member 148 into which the axles 146 a and 146 b are respectively mounted for possible rotating movement therein. The mounting of the axles 146 a and 146 b in the upwardly projecting plates 150 is reinforced by additional plates 152 mounted on the upward plates by bolts and nuts 154 holding bearings 156.
An arm 158 is affixed on one side of the member 148 to hold an actuator 160 the output rod 162 of which is attached to the one of the main cross support members 60 of the solar panel mounting subassembly 52, as is best shown in FIG. 4. Electrically powered actutarors per se are well known in the art and are commercially available. The actuator 160 of the preferred embodiment includes a switch (not shown) that causes the output rod 162 to move in or out, as wanted, to adjust the inclination or tilting of the solar panel mounting subassembly 52 together with the solar panels 78 mounted thereon. Electric power to the actuator 160 is provided by the battery 144, or may be provided by another power source similarly to the manner of providing power to the electric motor 122.
The location of the substantially horizontally disposed axle 146 in such a manner that it causes the solar panel mounting subassembly 52, together with the assembled solar panels 78 to be weight-balanced against precipitous and dangerous drop is a highly important feature of the invention and is described below in detail.
It was found in accordance with the present invention that the desired weight balancing of the solar panel mounting subassembly 52 can be accomplished only when the axis of horizontal pivoting movement or rotation represented by the axles 146 a and 146 b is in the centroid or substantially in the centroid of the combined weight solar panel mounting subassembly 52 and solar panels 78. The concept of centroid per se is well known in mathematics and engineering and is described here for the sake of completeness only by including description from readily available sources, such that may readily accessed by searching on the Internet. Thus, as it can be found by searching for “centroids” in GOOGLE, the free encyclopedia, Wikipedia, describes centroid as follows:
In geometry, the centroid or barycenter of an object X in n-dimensional space is the intersection of all hyperplaness that divide X into two parts of equal moment about the hyperplane. Informally, it is the “averagee” of all points of X. The centroid of an object coincides with its center of mass if the object has uniform density, or if the object's shape and density have a symmetry which fully determines the centroid. These conditions are sufficient but not necessary. The centroid of a finite set of points can be computed as the arithmetic mean of each coordinate of the points. The centroid of a convex object always lies in the object. A non-convex object might have a centroid that is outside the figure itself. The centroid of a ring or a bowl, for example, lies in the object's central void.
More specifically with regard to “center of gravity” and “moment of inertia” as is well known and can be found by searching on the Internet the following is noted for the sake of complete description of the present invention. The centroid, or center of gravity, of any object is the point within that object from which the force of gravity appears to act. An object will remain at rest if it is balanced on any point along a vertical line passing through its center of gravity. In terms of moments, the center of gravity of any object is the point around which the moments of the gravitational forces completely cancel one another.
The center of gravity of a rock (or any other three dimensional object) can be found by hanging it from a string. The line of action of the string will always pass through the center of gravity of the rock. The precise location of the center of gravity could be determined if one would tie the string around the rock a number of times and note each time the line of action of the string. Since a rock is a three dimensional object, the point of intersection would most likely lie somewhere within the rock and out of sight. The centroid of a two dimensional surface (such as the cross-section of a structural shape) is a point that corresponds to the center of gravity of a very thin homogeneous plate of the same area and shape. The planar surface (or figure) may represent an actual area (like a tributary floor area or the cross-section of a beam) or a figurative diagram (like a load or a bending moment diagram). It is often useful for the centroid of the area to be determined in either case. Symmetry can be very useful to help determine the location of the centroid of an area. If the area (or section or body) has one line of symmetry, the centroid will lie somewhere along the line of symmetry. This means that if it were required to balance the area (or body or section) in a horizontal position by placing a pencil or edge underneath it, the pencil would be best laid directly under the line of symmetry.
If a body (or area or section) has two (or more) lines of symmetry, the centroid must lie somewhere along each of the lines. Thus, the centroid is at the point where the lines intersect. This means that if it were required to balance the area (or body or section) in a horizontal position by placing a nail underneath it, the point of the nail would best be placed directly below the point where the lines of symmetry meet. This might seem obvious, but the concept of the centroid is very important to understand both graphically and numerically. The position of the center of gravity for some simple shapes is easily determined by inspection. One knows that the centroid of a circle is at its center and that of a square is at the intersection of two lines drawn connecting the midpoints of the parallel sides.
For further description and explanation of the concept of centroid and how to find it on a given object, reference is made to standard handbooks of mathematics, geometry and engineering.
Solar panels are usually of rectangular shape and therefore have a symmetry of the type described above that would render the determination of the centroid of each panel easy. Each of the solar panels used in the same assembly have practically the same weight and density distribution on their respective surfaces. Moreover, in accordance with the present invention the plurality of solar panels are preferably placed in a symmetrical pattern on the solar panel mounting subassembly 52. It is important that it was found in accordance with the present invention that the centroid is usually high in, or relative to the solar panel mounting subassembly 52, and can be found by routine experimentation that is sufficiently simple so as not to constitute undue experimentation. For this reason a mathematical or geometrical determination of the centroid is usually not necessary in the practice of the invention, although it can be performed. As noted before, the axis of rotation, namely the axle 144 (or as in the preferred embodiment of the axles 146 a and 146 b) is placed in the centroid, or substantially in the centroid in accordance with the present invention.
The herein shown preferred embodiments of the invention accomplish well the goal of weight balancing by utilizing the described mechanical construction. It should be noted that in the preferred embodiments the position of the horizontal axle 146 is as specifically shown in FIG. 4 in relation to member 62.
FIGS. 12 through 14 are directed to a preferred embodiment that is identical or substantially similar in construction with the just described embodiment but requires manual adjustment for East-West tracking and also for North-South declination. The component parts of this embodiment are described only to the extent they are different from or additional to the parts of the first and above described preferred embodiment.
Thus, the just noted preferred embodiment may lack the photosensor 124 of the first preferred embodiment. It lacks the electric motor 122 and lacks the electrically powered actuator 160 of the first preferred embodiment. Nevertheless, to enable manual tracking of the Sun, or to place the solar panel mounting subassembly 52 together with the assembled solar panels 78 into a desired East-West position a disk 164 is fixedly attached to the vertical axle 92 above the non-adjustable bearings 128. The disk 164 has a plurality of apertures or holes 166 close to its periphery. Similarly to the teeth 136 of the gear 132 of the first preferred embodiment, in this embodiment the apertures 166 are placed at least approximately 240, preferably at approximately 270 degrees around the periphery of the disk 164. Optionally, and as is shown for the presently described preferred embodiment, the disk 164 may have the apertures 166 around its entire periphery. A plate 168 is affixed to the axle housing 94 below the disk 164. The plate 168 includes an aperture that can be aligned with one of the plurality of apertures 166 on the disk 164. A bolt and nut combination 170 is normally used to secure the vertical axle 92, together with the solar panel mounting subassembly 52 and assembled solar panels 78 to remain stationary in any desired East-West position. When the bolt 170 is removed, then the vertical axle 92, the subassembly 52 with the solar panels 78 can be manually rotated to any desired new position.
FIG. 14 discloses a disk 172 that is fixedly attached to the horizontal axle 146 and rotates with it. The disk 172 also has apertures 174 capable of receiving a bolt 176. An elongated member 178 shown in FIG. 12 and by phantom lines in FIG. 14 is fixedly attached to one of the main cross support members 60 and has an aperture (not shown) that can be aligned with one of the plurality of apertures 174 of the disk 172. This can also receive the bolt 176 that can be secured with a nut (not shown). The apertures 174 are positioned around the periphery of the disk 172 so that any inclination or tilting of the subassembly 52 and solar panels 78 can be accomplished to the extent that it is practical for North-South adjustment of the solar panels 78. In this regard it should be noted that in virtually any location of planet Earth (except during the summer and winter solistice on the Equator or close to the Equator) ideal position of the solar panels 78 is at an angle to the horizontal. The just described structure enables the periodic adjustment of the inclination of the solar panels 78 by manual power.
FIG. 23 is a diagrammatic representation of the important feature of the present invention that the horizontal axis (corresponding to axle 146) for the tilting of the solar panel mounting subassembly 52 together with the assembled solar panels 78 is likely to be high relative to the main cross support members represented by 60 in this drawing figures. As noted above this is usually the necessary construction to have the axis of rotation in the centroid or substantially in the centroid.
FIG. 24 is a diagrammatic representation to show that the solar tracking assembly and mounting platform 40 of the present invention is capable of having a relatively large number of solar panels 78. A presently contemplated practical limit is approximately thirty (30) solar panels. However this practical limitation is not one of the invention per se, but rather is a matter of practical weight and size limitations which could be overcome with further improvement in technology, such as less heavy solar panels and stronger support materials.
Exemplary dimensions of the solar tracking assembly and mounting platform 40 of the present invention, designed and constructed to mount state-of-the-art commercially available solar panels are as follows. The solar panel mounting subassembly 52 (that can also be called “the frame”) is approximately 10×12 feet when designed to hold eight (8) solar panels of 3 feet by 5 feet. A frame that is designed to hold up to thirty (30) solar panels is 18×25 feet. Thirty state-of-the-art panels may provide up to 5 KW power.
In summary, several advantages of the above-described solar tracking assembly and mounting platform 40 of the present invention include the advantage of being weight balanced whereby the tilting of the subassembly 52 and solar panels 78 can be readily accomplished manually without major hazard to workmen and substantially decreased chance of property damage due to precipitous drop of the subassembly 52 and panels 78 around the horizontal axis. Having the subassembly 52 and the panels 78 weight balanced renders it easier for the electric motor 122 of the first preferred embodiment to function and prolongs the useful life of the equipment. Having the subassembly 52 and the panels 78 weight balanced also renders manual East-West rotation or adjustment easier.
Another important advantage is the ability to mount the solar tracking assembly and mounting platform 40 on a concrete pad 44 at a substantially lesser cost and effort than the usual mounting on poles as in the prior art. Still another advantage is that by utilizing three or four legs the solar panels can be at a relatively low height above the ground 50 whereby exposure of the solar panels 78 to wind pressure is substantially decreased. All of the foregoing contributes to the prolonged useful life and less requirement for maintenance and repair.
FIG. 25 is a diagrammatic representation of the height to which the subassembly 52 with the solar panels 78 is mounted under actual circumstances. The assembly 52 should be mounted at such height that even at the maximum desired inclination it still does not touch the ground 50. Moreover, at locations where there is substantial snow-cover during winter, the subassembly or frame 52 should not reach the snow (not shown) at its maximum desired inclination. Thus, it will be readily apparent to those skilled in the art that the practical minimum height of mounting of the subassembly 52 depends on the geographic location and climate conditions where the solar tracking assembly and mounting platform 40 is used and also depends on its actual size. Generally speaking, if no substantial snow-cover of ground is expected the edge of the solar panels 78 should be about 2 to 3 feet above the ground at the maximum desired tilt angle. If substantial snow-cover is expected the height of the snow-cover should be added to the above noted 2 or 3 feet of desired ground clearance.
As a practical example the following is noted. At a latitude of approximately 37 degrees North (where Cedar City, Utah) is located an exemplary solar tracking assembly and mounting platform 40 that has 24 panels (each panel being 3 feet by 5 feet) the horizontal axis of the subsassembly 52 is at approximately eight (8) feet above the ground. At this latitude the practical maximum inclination for the winter is about 55 degrees relative to the horizontal. The same height is also appropriate when thirty (30) such solar panels are included.
Referring now primarily to FIGS. 26 through 31 the presently most preferred embodiment of the solar tracking assembly and mounting platform 40 is disclosed. It is noted at the outset of the description of this presently most preferred embodiment that in many aspects of its construction it is identical or substantially identical with the previously described embodiments, and for this reason its description will focus on the parts, features and advantages that are either different or additional to the previously described embodiments.
FIG. 26 is a perspective view of the presently most preferred embodiment. The solar panel mounting subassembly 52 is constructed in the same or substantially the same manner as for the previously described two embodiments. This embodiment, however, is supported by three legs 42, and each of the legs terminates in a flat plate 46 that is positioned to point inward, toward the center of the triangle formed by the legs 42, as is shown in the drawing figure. The legs 42 are attachable to a concrete pad 44 as in the previously described embodiments. This embodiment includes cross-members or braces 200 attached to a plate 202 that is itself attached to the bottom of the vertical axle housing 94. It was found in experience that the braces 200 substantially stabilize the entire solar tracking assembly and mounting platform 40, make it more resistant to wind and lengthen its working life. As in the previously described embodiments in the axle housing 94 is the axle 92 that rotates the solar panel mounting subassembly 52 in the East-West direction. The axle 92 has a fixedly attached gear 132 that is in meshing engagement with the output gear 138 of the electric motor 122. Inasmuch as rotation in the East-West sense is not required beyond approximately 240 degrees this embodiment includes a limit switch 204 that is triggered by the limit switch trigger 206 mounted to the gear 132. In order to further stabilize the axle 92 and thereby the entire solar tracking assembly and mounting platform 40 a stainless steel sleeve 208 having a smoothly machined outer surface is welded to the axle 92. A bushing support ring 210 is supported by the legs 42 and an oil impregnated nylon bushing 212 is affixed by a plurality of bolts 214 to the bushing support ring 210. The bushing 212 is further supported and held in place by metal retainers 215 a that are held with bolts 215 b (FIG. 8). The nylon bushing 212 interfaces with the smoothly machined outer surface of the sleeve 208. This is best shown in FIGS. 27 through 30.
In order to accomplish the North-South declination or tilting of the solar panel mounting subassembly 52 an electric motor or tilt motor 216 is mounted to a plate 218 that is itself mounted to an arm 220 (shown at an approximately 45 degree angle in FIG. 27) so that the motor 216 moves in the East-West direction together with the rotating axle 92. The tilt motor 216 includes an output gear 222. The solar panel mounting subassembly 52 includes a gear 224 in meshing engagement with the output gear 222 of the tilt motor 216. This embodiment also includes a tilt limit switch 226 and a tilt limit switch trigger 228. These parts and features are best shown in FIGS. 27 and 31.
In the presently most preferred embodiment also, like in the previously described embodiments, the horizontally disposed axle 146 (shown only schematically in FIG. 31)on which the solar panel mounting subassembly 52 tilts in the North-South sense is also placed in the centroid or substantially in the centroid of the combined weight solar panel mounting subassembly 52 and solar panels 78. This accomplishes such balancing of the combined solar panel mounting subassembly 52 and solar panels 78 that a precipitous and dangerous drop is avoided, and if necessary the tilting can be readily accomplished by human force without undue danger. Perhaps just as importantly such weight balancing makes it possible to use a tilt motor 216 of much lesser power than what would be otherwise required if the combined solar panel mounting subassembly 52 and solar panels 78 were not weight balanced and such motor will have a long working life. It should also be readily apparent from the foregoing description that the just described most preferred embodiment includes all of the advantages of the present invention, is capable of virtually automatic operation by following in the East-West direction the daily route of the Sun in the sky, and also by tilting, as controlled by a computer or otherwise programmed, the combined solar panel mounting subassembly 52 and solar panels 78 in the North-South sense to adjust for seasonal changes of the position of the Sun in the sky.

Claims

1. A solar tracking mechanism and mounting platform adapted for supporting a plurality of solar panels that comprise solar energy collecting means and for adjusting said solar panels in an East-West direction and for also adjusting the declination of said panels relative to the horizontal, said adjustment being considered adjustment for North-South location and in accordance to seasons, the solar tracking mechanism and mounting platform comprising:

a plurality of legs;

a solar panel mounting subassembly that forms a frame adapted for receiving the plurality of solar panels, the subassembly being mounted to the legs;

first means mounted to the legs for rotating the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment;

second means mounted to the first means for pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons; the second means holding the solar panel mounting subassembly in a substantially weight balanced position at any angle of declination that is practically used for North-South and seasonal adjustment.

2. A solar tracking mechanism and mounting platform in accordance with claim 1 wherein the substantially horizontally disposed axis is located substantially in the weight centroid of the solar panel mounting subassembly.

3. A solar tracking mechanism and mounting platform in accordance with claim 2 additionally comprising an electric motor to power the first means for rotating the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment and an electrically powered actuator to power the second means for pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons.

4. A solar tracking mechanism and mounting platform in accordance with claim 2 additionally comprising a first electric motor to power the first means for rotating the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment and a second electric motor to power the second means for pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons.

5. A solar tracking mechanism and mounting platform in accordance with claim 4 additionally comprising switch means for limiting the rotation of the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment of at least 240 degrees.

6. A solar tracking mechanism and mounting platform in accordance with claim 5 additionally comprising second switch means for limiting the pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons within a predetermined set range of degrees.

7. A solar tracking mechanism and mounting platform in accordance with claim 2 additionally comprising a plurality of solar panels mounted to the solar panel mounting subassembly and wherein the second means is adapted for holding the solar panel mounting subassembly together with the plurality of solar panels in the substantially weight balanced position.

8. A solar tracking mechanism and mounting platform in accordance with claim 2 wherein the first and second means are powered manually.

9. A solar tracking mechanism and mounting platform in accordance with claim 2 that has no more than 3 legs.

10. A solar tracking mechanism and mounting platform adapted for supporting a plurality of solar panels that comprise solar energy collecting means and for adjusting said solar panels in an East-West direction and for also adjusting the declination of said panels relative to the horizontal, said adjustment being considered adjustment for North-South location and in accordance to seasons, the solar tracking mechanism and mounting platform comprising:

a plurality of legs;

first means mounted to the legs for rotating the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment, said first means including a substantially vertically disposed axle fixedly connected to the solar panel mounting subassembly, the substantially vertically disposed axle including a smoothly machined stainless steel outer surface, the first means further including an oil impregnated nylon bushing in working engagement with the stainless steel outer surface;

second means mounted to the first means for pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons; the second means holding the solar panel mounting subassembly in a substantially weight balanced position at any angle of declination that is practically used for North-South and seasonal adjustment, the substantially horizontally disposed axis being located substantially in the weight centroid of the solar panel mounting subassembly.

11. A solar tracking mechanism and mounting platform in accordance with claim 10 additionally comprising an electric motor having an out-put gear, the substantially vertically disposed axle being fixedly connected to a gear that is in meshing engagement with the out-put gear of the electric motor, the electric motor rotating the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment.

12. A solar tracking mechanism and mounting platform in accordance with claim 11 additionally comprising switch means for limiting the rotation of the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment of at least 240 degrees.

13. A solar tracking mechanism and mounting platform in accordance with claim 11 additionally comprising a second electric motor to power the second means for pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons.

14. A solar tracking mechanism and mounting platform in accordance with claim 13 additionally comprising second switch means for limiting the pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons within a predetermined set range of degrees.

15. A solar tracking mechanism and mounting platform in accordance with claim 11 additionally comprising a plurality of solar panels mounted to the solar panel mounting subassembly and wherein the second means is adapted for holding the solar panel mounting subassembly together with the plurality of solar panels in the substantially weight balanced position.

16. A solar tracking mechanism and mounting platform in accordance with claim 11 that has no more than 3 legs.

17. A solar tracking mechanism and mounting platform including a plurality of solar panels that comprise solar energy collecting means and for adjusting said solar panels in an East-West direction and for also adjusting the declination of said panels relative to the horizontal, said adjustment being considered adjustment for North-South location and in accordance to seasons, the solar tracking mechanism and mounting platform comprising:

a plurality of legs;

a solar panel mounting subassembly that forms a frame adapted for supporting the plurality of solar panels, the subassembly being mounted to the legs;

first means mounted to the legs for rotating the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment, said first means including a substantially vertically disposed axle fixedly connected to the solar panel mounting subassembly, the substantially vertically disposed axle including a smoothly machined stainless steel outer surface, the first means further including an oil impregnated nylon bushing in working engagement with the stainless steel outer surface; the first means still further including a first electric motor having an out-put gear, the substantially vertically disclosed axle being fixedly connected to a gear that is in meshing engagement with the out-put gear of the first electric motor, the first means yet additionally including switch means for limiting the rotation of the solar panel mounting subassembly around a substantially vertically disposed axis for East to West adjustment of at least 240 degrees;

second means mounted to the first means for pivoting the solar panel mounting subassembly and the supported solar panels around a substantially horizontally disposed axis for adjustment of North-South location and for seasons; the second means holding the solar panel mounting subassembly and solar panels in a substantially weight balanced position at any angle of declination that is practically used for North-South and seasonal adjustment, the second means comprising a second electric motor, the substantially horizontally disposed axis being located substantially in the weight centroid of the solar panel mounting subassembly and solar panels, and the second means additionally including switch means for limiting the pivoting the solar panel mounting subassembly around a substantially horizontally disposed axis for adjustment of North-South location and for seasons within a predetermined set range of degrees.

18. A solar tracking mechanism and mounting platform in accordance with claim 17 that has no more than 3 legs.

19. A solar tracking mechanism and mounting platform in accordance with claim 17 additionally including a rechargeable battery, said battery capable of powering the first and second electric motors.