Solar Tracking System

TECHNICAL FIELD

The present invention is directed to a tracking system which allows an array of solar collectors to better track the sun throughout the seasons of a year. The invention may also be directed to a drive system to rotate the array and to allow multiple units to be driven together. The array can comprise PV panels, solar thermal panels, bifacial modules, or any other product that could benefit from the tracking system.

BACKGROUND

PV panels (also known as a PV array) are most efficient when sunlight strikes the panels at right angles. At the equatorial regions the panels can be supported on a substantially horizontal axis. The efficiency of the array can be improved by up to 30% if the array can rotate about the horizontal axis from east to west during the day to maintain array at right angles to the sun. This type of rotation tracking is about a single axis and is commonly called a “single axis tracker”.

At increasing latitude (moving away from the equator), it is known to incline the array to compensate for the latitude. The array can be rotated about the inclined axis (also known as the primary axis) from east to west to improve the solar collection. At increasing latitudes however, the arc of the sun across the sky differs quite significantly between summer (when the sun is higher in the sky), and winter (when the sun is lower in the sky). It is known to provide a dual axis tracker which can compensate for the different trajectories of the sun at greater latitudes but these trackers are complex and expensive.

Automatic tracking systems require actuators or motors to operate the system. It is common to have each PV array driven by a separate motor. This adds to the cost and complexity of the system. Coupling two or more PV arrays together to be driven by single motor results in a complicated and expensive system especially for the heavy and complex dual axis tracking systems. There would be an advantage if it were possible to provide a tracking system which could have multiple arrays controlled by a single, or a few drivers.

Wind resistance is a problem for many solar arrays. This can result in many arrays being fixed in position to prevent damage by wind load, but this results in an efficiency reduction as the array cannot rotate. Alternatively, the tracking system can be made robust and able to withstand wind loading, but this adds to cost and weight and therefore increases the forces required to operate the system. There would be an advantage if it were possible to provide a tracking system which could have wind tolerance but not have the associated disadvantages of complexity, weight etc.

Self-shading is a problem for many solar arrays and requires the arrays to be spaced apart by a quite considerable distance. The problem is more prevalent in winter when the sun is lower in the sky. There would be an advantage if it were possible to provide a tracking system which could have less self-shading to allow arrays to placed closer together, particularly in a north-south spacing, and thus allowing the arrays to be spaced further apart laterally to enable better collecting of morning and late afternoon sun and without increasing the footprint size of the arrays.

It is an object of the invention to provide a solar tracking system which may overcome at least some of the above-mentioned disadvantages or provide a useful or commercial choice in the marketplace.

Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a solar tracking apparatus comprising an array frame assembly adapted to support at least one solar collecting product, having opposed ends,

rotation means comprising a pair of spaced apart drive members to enable the array frame assembly to rotate to at least track the sun from east to west along an inclined primary axis of rotation, the said opposed ends of the array frame assembly being proximal to the drive members,

and adjustment means to enable the array frame assembly to be adjusted relative to the primary axis of rotation to allow for seasonal changes in the sun's elevation and changes in the sun's declination throughout each day,

the adjustment means being operable adjacent each said end of the array frame assembly and comprising a first part connected relative to each drive member and a second part adjustably connected to the first part to enable said adjustment of the array frame assembly relative to the primary axis of rotation.

In another form, the invention may comprise a solar tracking apparatus comprising an array frame assembly adapted to support at least one solar collecting product, rotation means to enable the array frame assembly to rotate to at least track the sun from east to west along a primary axis of rotation, and adjustment means to enable the array frame assembly to be adjusted relative to the primary axis of rotation to allow for both seasonal changes in the sun's elevation, and daily changes in the suns declination angle (position relative to the equator).

In this manner, the solar tracking apparatus can deliver the higher efficiency of a two axis tracker but with the simplicity and cost effectiveness of a single axis tracker. In all seasons the apparatus enables solar energy to be captured in the early morning and late afternoon in a manner which is more efficient than most other tracking devices and especially single axis tracking devices.

In an embodiment, the apparatus can follow the sun's movement around a tilted longitudinal axis from east to west (the primary axis of rotation), the angle of tilt depending on the latitude, and can also be adjusted about a secondary east-west axis, typically in an incremental manner, (the adjustment means) to provide the unique ability of the tracking apparatus to allow for seasonal changes in the sun's elevation and position early and late in the day.

It is preferred that the adjustment means allows part of the array frame assembly to be raised above the primary axis of rotation and part of the array frame assembly to be lowered below the primary axis of rotation. Suitably, the array frame assembly is adjusted by offsetting the opposed ends of the assembly such that one end of the assembly is offset above the primary axis of rotation and the opposite end of the assembly is offset below the primary axis of rotation. Suitably, the offset is about a secondary axis extending across the assembly and about midway there along.

This offset can provide the unique characteristic that the primary and secondary axis are normal [right angles] to each other only at midday or at the eqinox settings. In contrast, existing dual axis trackers have their axis perpendicular to each other at all times.

The solar tracking apparatus can be positioned on the ground, on a roof, on a platform, or at any other suitable position. It is not considered that any unnecessary limitation should be placed on the invention merely by the exemplification of certain non limiting examples of preferred locations.

The apparatus can be used to support at least one solar collecting device. This may include at least one PV panel, solar heat collector and the like. The type of PV panel may vary and may include monocrystalline panels, multicrystal photovoltaic panels, solar laminates, bifacial panels, solar concentrators, and the like. The dimensions of the solar collecting device may vary to suit. As an example, a typical PV panel will be rectangular and will have a length of between 1-2 m and a width of between 0.5-1.5 m. However, PV panels having dimensions of between 0.2-2.2 m in length and 0.2-1.2 m in width may also be suitable. Solar heat collectors may include tubes, pipes, heat boxes and the like. Solar concentrators may include reflective surfaces, lenses and the like, concentrating light or heat onto relatively small areas.

The array frame assembly may support one, or a multiple of, solar collecting devices and may support all PV panels or a mix of different types of solar collecting devices.

The array frame assembly may have any suitable shape and size. To result in less lateral shading, the array frame assembly will preferably be substantially rectangular in configuration. The array frame assembly may have a length of between 0.5-30 m and a width of between 0.5-10 m and will typically have a length of between 3-6 m and a width of between 1.5-2.2 m. Of course, this can vary to suit.

The array frame assembly may be made of any suitable material or materials. It is considered expedient that the frame assembly is made of metal. A suitable metal will be steel which may be treated for corrosion resistance. For instance, the metal may be painted, powder coated, anodised, galvanised and the like. Alternatively, the metal may comprise aluminium. While other metals can also be used, steel and aluminium will probably be the most cost-effective in the manufacture of the frame assembly. The frame assembly may be made from a material other than metal. For instance, the frame assembly may be made from strong engineering plastics. It is also envisaged that the frame assembly or parts of the frame assembly can be made from laminated material. It is also envisaged that the frame assembly may be made from different materials such as to benefit from the strength of some materials and the weight of other materials.

The frame assembly may comprise elongate members which may be attached to each other or relative to each other to form the assembly. The elongate members may be attached by any suitable means which may include screw fasteners, nut and bolt fasteners, rivets, welding, crimping, and the like. A combination of fastening means may also be provided. The elongate members may comprise tubes, solid bars, elongate box shaped members, L-shaped members, C shaped members, U-shaped members, channel type members and the like. A combination of different types of elongate members may be provided. The assembly may include cross members, struts, strengthening members, and the like. The assembly may include a platform of some kind on which the PV panels can be supported. The platform may comprise a mesh, a perforated panel, a grid like arrangement, a combination, cross members and the like. The array frame may also take the form of a single, straight, rigid member onto which PV panels are fixed crossways.

One advantage of the present invention and particularly of the configuration of the solar tracking apparatus is the ability to add at least one extension member to the array frame assembly such that additional PV panels or other types of solar collecting devices or reflectors can be attached. A non-limiting example of this is illustrated with reference numeral 78 in FIGS. 7B.

It should be appreciated that no unnecessary limitation should be placed of the invention merely by the exemplification of a non-limiting example of an extension member.

There may be circumstances where it may be advantageous to have more than one array frame assembly. For instance, the solar tracking apparatus may have a pair of array frame assemblies which can be positioned next to each other. These may be adapted for rotation along a common primary axis of rotation.

The solar tracking apparatus includes a rotation means to enable the array frame assembly to track the sun from east to west and this is enabled by rotating the array about the primary axis of rotation.

The primary axis of rotation will typically be tilted or angled depending on the latitude. Typically, the primary axis of rotation will be set between 16°-22° depending on the latitude. The rotation means will typically comprise a rotatable shaft and there will typically be a pair of spaced apart rotatable shafts with the array frame assembly being positioned between the spaced apart shafts. The axis of rotation of each shaft will typically be aligned and the aligned axis will typically comprise the primary axis of rotation. This primary axis of rotation will typically be angled between 16° and 22° depending on the latitude of the area where the solar tracking apparatus is to be used.

The adjustment means can provide an additional adjustable offset to the primary axis of rotation of up to another 38° allowing the solar tracking apparatus to be well-suited to latitudes between 50° north and 50° south.

The adjustment means may comprise a manual adjustment means. Alternatively, the adjustment means may be automated using actuators and the like. The adjustment means can be operated remotely if desired. If the adjustment means is a manual adjustment means, it may comprise some form of adjustable locking means or clamping means or other type of holding means.

In an example, the adjustment means may comprise part of a sub frame assembly (described in greater detail below) with the array frame assembly being adjustably mounted relative to the sub frame assembly. This can be achieved using some form of adjustable locking means. A non-limiting example of this type of adjustment means is illustrated at least in FIG. 3 and another non-limiting example of an adjustment means is illustrated at least in FIG. 6A and FIG. 6B.

Alternatively, the adjustment means may comprise parts other than a sub frame assembly. For instance, the adjustment means may comprise adjustable arms or something similar and a non-limiting example of this type of adjustment means is illustrated at least in FIG. 7A, FIG. 7B and FIG. 8.

A sub frame assembly may be provided to support the array frame assembly and to enable the array frame assembly to rotate relative to at least part of the sub frame assembly. The sub frame assembly may be operatively associated with the rotation means such that rotation of the rotation means causes swinging of the sub frame assembly (for instance from east to west) and as the array frame assembly is attached to the sub frame assembly, the array frame assembly will also swing (for instance from east to west). The array frame assembly may be adjustably mounted to the sub frame assembly to compensate between the summer sun and the winter sun especially in higher latitudes. This will be described in greater detail below.

The sub frame assembly may be made from any suitable material and the materials described with reference to the array frame assembly may be suitable. In a preferred embodiment, the sub frame assembly comprises a number of elongate members of various configurations which can be attached to each other to form the sub frame assembly. This will be described in greater detail below.

A support frame assembly may be provided to support the remainder of the solar tracking apparatus at the correct inclination.

The support frame assembly may be separate and attached to the sub frame assembly. Alternatively, the support frame assembly can form part of the sub frame assembly whichever is more convenient. In a further alternative, the support frame assembly can be indirectly attached to the array face assembly such that a sub frame assembly is not required (see for instance the example in FIG. 8). The support frame assembly will typically support the solar tracking apparatus at an angle generally along the primary axis. The support frame assembly may be attached to each end of the sub frame assembly.

Suitably, the support frame assembly comprises a first sub assembly at the “polar end” of the remainder of the solar tracking apparatus, and a second sub assembly at the “equatorial end”. The first sub assembly may be taller and the second sub assembly may be shorter thereby assisting in positioning the apparatus at the correct tilt angle depending on the latitude.

The support frame assembly may be made of any suitable materials and the materials described with reference to the array frame assembly may be suitable. In an example, the support frame assembly will comprise elongate leg members. These may be adjustable in length if desired. Each sub assembly may comprise a pair of leg members (see FIG. 3 as an example). Alternatively, each subassembly may comprise a single leg member (see FIG. 6A as an example). In yet a further alternative, the support frame assembly may comprise a cradle, a non-limiting example of this being described with reference to FIG. 8. It is not considered that any unnecessary limitation should be placed on the support frame assembly.

It is preferred that the support frame assembly supports the rotation means. Thus, part of the support frame assembly may support a rotatable shaft which forms part of the rotation means.

The solar tracking apparatus may be driven by a drive means. The drive means may comprise a motor, a ram, an actuator or any other suitable drive means. The drive means may be operatively connected to the rotation means to cause rotation of the array frame assembly.

The drive means may be directly coupled to the rotation means, or may be spaced from the rotation means and operatively connected to the rotation means by an intermediate member which may comprise an arm, shaft, pulley, cog, chain, belt and the like.

In a preferred aspect of the present invention, there is provided a longitudinal drive system to enable more than one solar tracking apparatus to be driven by a drive means (e.g. a motor). Thus, in a preferred aspect of the present invention, two or more solar tracking apparatus may be operatively connected to be driven by a single drive means. A longitudinal drive system may be provided to enable such operative connection. The longitudinal drive system may comprise an interconnecting rotatable shaft which interconnects the rotation means of one solar tracking apparatus to the rotation means of a second solar tracking apparatus. The interconnecting rotatable shaft may comprise a single shaft or a number of shafts which are interconnected. An example of a longitudinal drive system interconnecting two separate solar tracking apparatus is illustrated as reference numeral 82 in FIG. 14. Alternatively, the longitudinal drive system may comprise a belt and pulley system or a chain and cog system as at rear in FIG. 14 or any other suitable type of longitudinal drive system.

In another preferred aspect of the invention there is provided a lateral drive system. The lateral drive system may be provided in addition to or instead of the longitudinal drive system. It is preferred that the lateral drive system is provided in addition to the longitudinal drive system. A non limiting example of a lateral drive system is illustrated as reference numeral 131/134 in FIG. 14. The lateral drive system may comprise at least one reciprocating arm member or shaft member as illustrated in FIG. 14. It should however be appreciated that no particular limitation should be placed on the invention merely by exemplification of a particular type of lateral drive system.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

FIG. 1A. Illustrates an eastern elevation of the apparatus showing typical winter offset at noon, and illustrating the array face assembly at a greater tilt angle to place the array face assembly at right angles to the winter sun's rays.

FIG. 1B. Illustrates an eastern elevation showing typical summer offset at noon and illustrating the array face assembly at a lesser tilt angle to place the array face assembly at right angles to the summer sun's rays.

FIG. 2A. Illustrates a top view showing the position of array face assembly on a typical winter morning and afternoon.

FIG. 2B. Illustrates a top view showing the position of array face assembly on a typical summer morning and afternoon.

FIG. 3. Illustrates a top right view of an apparatus according to a first embodiment of the invention and illustrating an array frame assembly locked to one example of a sub frame assembly which is attached to the rotatable shafts, and particularly illustrating the double V frame bracing arms on the sub frame assembly.

FIG. 4A. Illustrates an end view of the array frame assembly of FIG. 3 and particularly illustrating the fixed locking brackets and V-shaped bracing members.

FIG. 4B. Illustrates a side view of right hand end of array frame assembly of FIG. 3 and particularly illustrating the fixed lockable bracket and v-shaped bracing members.

FIG. 5. Illustrates a top right view of an apparatus with a slightly different sub frame shape and only one pair of V members supporting the array frame assembly. These members do not pivot on the sub frame.

FIG. 6A. Illustrates a top right view of an apparatus according to a second embodiment of the invention and particularly illustrating a curved rail sub frame, the position of the array face assembly of the apparatus being that for a winter's day.

FIG. 6B. Illustrates an eastern elevation of the apparatus of FIG. 6A in the equinox position and particularly illustrating the curved rail sub frame and the wheels and guides.

FIG. 6C. Illustrates a further modification of the sub rail embodiment.

FIG. 7A. Illustrates an eastern elevation of an apparatus according to a third embodiment of the invention and particularly illustrating adjustable arms used to achieve the offset without requiring a sub frame assembly, the position of the array face assembly of the apparatus being that for a winter's day.

FIG. 7B. Illustrates the apparatus of FIG. 7A with the position of the array face assembly of the apparatus being that for a summer's day, and also illustrating the position where additional PV modules can be added.

FIG. 8. Illustrates a top right view of the apparatus of the third embodiment, the position of the array face assembly of the apparatus being that for a winter's day, and particularly illustrating adjustable arms, a part of an example of a longitudinal drive system comprising a torque shaft which can connect longitudinally adjacent trackers, and a support frame assembly comprising A-frame end supports connected via ground supported members.

FIG. 9. Illustrates a top right view of a support frame to support a PV tracker, and which has two pairs of outwardly leaning A-frames with ground supported connecting members with corner anchoring points to the ground or other structure. A tracker on this frame may operate independently of other trackers.

FIG. 10. Illustrates a top right view of a tracker support system where longitudinally adjoining trackers are connected to a common drive shaft with cantilevered universal or CV joints. Bearing brackets can be adjusted in height and the torque shaft length can be adjusted with telescopic action.

FIG. 11A. Illustrates an eastern elevation of an example of a longitudinal drive system to connect two solar tracking apparatus with a common torque shaft and where the common torque shaft does not have a supporting function and where the distal ends of the U-joints are held at the desired tilt angle by brackets on distal ends of an arm spanning the A-frame on the southern end of one tracker and the northern end of the next, polar positioned tracker.

FIG. 11B. Illustrates a drive system similar to that illustrated in FIG. 11A except that the U-joints are now on extension brackets from the A-frames.

FIG. 12A. Illustrate east-west sections of a lateral drive system which can connect and operate multiple apparatus, with the three illustrations representing movement of a said apparatus from midday to late afternoon then the start of the return rotation to the east.

FIG. 12B. Illustrates east west sections of the drive system of FIG. 12A showing movement of the apparatus back to the eastern most operating position then the early part of the daily movement.

FIG. 13A. Illustrates an eastern section through a ground supported member showing a lateral drive system according to a first embodiment of the invention which has a C-channel style of reciprocating arm.

FIG. 13B. Illustrates an eastern section through a ground supported member showing a lateral drive system according to a second embodiment of the invention which has double wheel guides and pipe style reciprocating arm.

FIG. 14. Illustrates a top right view showing four separate apparatuses stacked side by side and end to end with a lateral drive system and two longitudinal drive systems, the one in the foreground being of the torque shaft with U-joint design described in detail and the one in the rear illustrating an alternative cog and chain (or belt and pulley) drive arrangement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

NOTE: the illustrations are for the northern hemisphere, are schematic and not to scale, and all described embodiments are for the northern hemisphere.

The solar tracking apparatus of the embodiments all have an array frame assembly 13. In some embodiments the array frame assembly is adjustably attached to a sub frame assembly (59FIG. 3, or 61/62 FIG. 6A/6B) which is fixed to rotating drive shafts 12. In other embodiments there is no sub frame assembly and the array face is adjustable mounted to the drive shafts (e.g. FIG. 8). In all embodiments there is provided a support frame assembly which can comprise tapering legs (FIG. 1), a single post (FIG. 6A), or a cradle (FIG. 8).

The invention as illustrated and described in the preferred embodiments is a solar tracking system where the solar array can follow sun's movement by moving the array face; (A) around a primary tilted, longitudinal axis from east to west daily and, (B) around a secondary east-west axis with an incremental adjustment. This incremental adjustment involves raising one end of the array frame higher than the pivot point of the longitudinal axis line at one end and lowering the other end of the array frame below the other pivot point of the longitudinal axis (if adjustment is made at noon). This gives the tracker the ability to allow for the seasonal changes in the suns elevation and position early and late in the day, and enables the tracker to direct the array face to be nearly perpendicular to the sun early and late in the day and throughout the whole year.

The tracker may also incorporate a novel east-west drive method and a support system incorporating an innovative (north-south) drive system. The system has higher wind tolerance and less self-shading than most 2-axis and azimuthal single axis trackers and requires less driving force than most tracking systems. Its design also allows the expansion of the sun capturing area in the warmer months.

One embodiment includes a novel support system incorporating two new drive systems, one which drives side by side trackers (a lateral drive system) and one which can drive end to end trackers (a longitudinal drive system). This means many arrays can be turned by one drive motor.

The array frame assembly which may be rectangular and, when in operating mode, is oriented north-south holding one or more PV or CPV modules or solar energy collecting devices,

The support frame assembly which holds the polar end of tracking array higher than the equatorial end via two rotatable shafts. A line between these two rotatable shafts represents a primary axis line which tilts toward the equator.

The array frame assembly rotates around this axis line from east to west and back again daily.

An adjustment means comprising a method of offsetting each end of the array frame oppositely up or down away from the pivot point on the rotatable shafts is provided. These adjustments are made incrementally as the seasons progress and may involve simultaneously moving one end up and the other one down to change the inclination angle. Alternatively the adjustment means can adjust one end initially and then adjust the other end.

Different ways of achieving this offset are outlined. One way can require the array frame to be tipped up or down then locked on a sub frame which is suspended between the rotatable shafts. Another involves using adjustable arms to effect the offset.

The tracker could operate independently with its own support system as a stand-alone tracker or if the described drive systems illustrated in FIGS. 10, 11A, 11B are used, a common drive shaft could support the northern end of one array and the southern end of an adjoining array.

Reference numerals and identifiers for the major parts of the system described in the embodiments are as follows. The illustrated embodiments may contain additional reference numerals:

10 array face
12 rotatable drive shaft
13 array frame assembly
15 primary (north-south) axis line
16 tilt angle of axis line, (Ø) which will be set between 16 and 22 degrees depending on latitude
17 the offset angle Ø1
18 angle of inclination of the array frame (Ø2) which is the sum of Ø+Ø1
19 equatorial end support structure
20 polar end support structure
L the offset distance of the array face from the axis line at the equatorial end
L1 the offset distance of the array face from the axis line at the polar end.
- (For trackers with a sub frame L will equal L1 unless the array face is set higher than the primary axis line for weight balancing reasons)
L3 the offset distance at polar end in summer, generally smaller than L and L1
L4 the offset distance at the polar end in summer. L3 and L4 may or may not be equal in embodiments not having a sub frame.
24 closer edge of array frame
51 bearing
52 bracket onto which bearing is mounted (height adjustable). Can also be seen as a height adjustable bracket. Raising this bracket pushes the secondary axis line to the right
53 lockable bracket fixed to the array frame
53A equatorial end fixed bracket
53B polar end fixed bracket
54 V-shaped bracing members
55 floating lockable bracket
56 secondary east west axis line
57 V-shaped array frame supports
sub frame assembly
502 locking pin
60 pivot member between connecting rod and sub frame
61 curved (or angled) member fixed to array frame
62 curved sub frame suspended between rotatable shafts
63 guides fixed to curved rail and lockable to array frame with locking pin
64 wheels fixed to curved rail which run on sub frame rail
65 bracing arm
71 adjustable arms which can pivot on array frame, on the rotatable shaft and at the elbow in between
72 pivotable elbow
73 sliding arm pivotably attached to the upper adjustable arm which slides along pin on lower arm and locked when in the desired position
74 tie strap to stop array from swinging down when approaching a high inclination
78 position of additional solar modules, solar collection devices or reflectors which can be mounted between the equinoxes at the warmer end of the year
81 universal joint or CV joint
82 torque shaft
83 extension bracket for holding bearing and rotatable shaft at the desired angle
84 ground supported members, converging towards the equatorial end
92 higher, polar, outwardly leaning (side view) A-frame (end view)
93 lower, equatorial, outwardly leaning A-frame
95 fasteners such as anchor stakes or bolts
96 spacer/packer pad
102 smaller diameter extendable/retractable shaft which can be telescopically slid in or out to change the length of the torque shaft and locked in position with a pin or lock nut
103 locking pin
111 arm spanning A-frame supports holding bearing bracket and hence the universal joint at the desired angle
112 bearing bracket
113 bracket connecting spanning arm to A-frame supports
121 connecting rod
122 reciprocating arm
131 C-section reciprocating arm
132 guide wheels/bearings
133 fixing bracket
134 pipe or rod reciprocating arm
135 wheel guides
136 axle for wheel guides
137 lug fixed to reciprocating arm
138 pivot pin in plastic bearing
141 torque shaft with cog and chain or pulley and belt
142 cog or pulley
143 chain or belt

Referring now in greater detail to the Figures and initially to FIG. 1A, FIG. 1A illustrates schematically the basic position of the array face 10 at midday in winter and illustrates the offset angle. Conversely, FIG. 1B illustrates schematically the basic position of the array frame assembly 10 at midday in summer and illustrates the lesser (and reversed) offset angle.

Array face assembly 10 is operatively mounted to a pair of spaced apart rotating means in the form of two rotatable shafts 12, one shaft 12 being positioned at the upper end of support frame assembly 19 and the other shaft being positioned at the upper end of support frame assembly 20.

The shafts 12 are aligned along a primary axis of rotation 15 which can also be called the primary (north-south) axis line. The axis of rotation 15 is inclined depending on the approximate latitude. The inclination angle of the axis line is identified as Ø in FIG. 1A and will be set between 16° and 22° depending on latitude.

An adjustment means is provided to enable the array face to be further tilted or offset from the axis of rotation 15. The letter L illustrates the offset distance of the array face from the axis line 15 at the equatorial end of the apparatus while the letter L1 illustrates the offset distance of the array face from the axis line 15 at the polar end. As illustrated in FIG. 1A (winter offset) and FIG. 1B (summer offset), the offset distance L 3 at the polar end in summer is generally less than the offset in winter.

Reference numeral 17 (see FIG. 1A) illustrates the angle of inclination of the array frame Ø2 which is the sum of Ø+Ø1. Reference numeral 18 illustrates the offset angle Ø1.

FIG. 2A illustrates a top view showing position of the array frame assembly 10 on the typical winter morning and afternoon while FIG. 2B illustrates a top view showing position of the array frame assembly 10 on a typical summer morning and afternoon. The rotatable shafts 12 are illustrated in each Figure as a fixed point of reference.

FIG. 3 illustrates a complete solar tracking apparatus according to a first embodiment. The apparatus briefly comprises an array frame assembly 13 which is supported by a sub frame assembly 59. Sub frame assembly 59 has opposed ends, each end being fixed to a rotation means in the form of a drive shaft 12. Thus, rotation of drive shaft 12 in a clockwise or anticlockwise manner will cause the sub frame assembly 59 to swing in a corresponding clockwise or anticlockwise manner which will cause the array frame assembly 13 to swing and thereby able to track the sun. Each drive shaft 12 is mounted to an upper end of a support frame assembly 19, 20. The support frame assembly, in this particular embodiment, comprises a first shorter sub assembly 20 at one end of the apparatus, and a second longer sub assembly 19 at the other end. Each sub assembly comprises a pair of leg members. A bearing 51 is positioned on a height adjustable bearing bracket 52, and the bracket is mounted to the upper end of each sub assembly.

Sub frame assembly 59 comprises an elongate member which is shaped to roughly adopt an elongated U-shape. Each end of the elongate member is fixed to the corresponding drive shaft 12

The array frame assembly 13 supports one or more PV panels. Frame assembly 13 comprises a metal frame which is supported by the sub frame assembly 59 in the following manner. The lower end of the frame assembly 13 (see FIG. 3) is attached to the lower end of the sub frame assembly 59 by a lockable bracket 53A. The lockable bracket 53A can lock onto the sub frame assembly 59 at various positions to adjust the angle of the array frame assembly 13 relative to the sub frame assembly. The sub frame assembly is provided with a plurality of spaced apart openings and the lockable bracket 53A can lock to any one of these openings via a locking pin.

In a similar manner, a second floating lockable bracket 55 is provided on the other end of the sub frame assembly 59 and this bracket 55 can also be locked into any one of the spaced apart openings on this other end of the sub frame assembly.

A pair of V shaped bracing members 54 is provided to space the upper end of the array frame assembly from the sub frame assembly. Another pair of similar bracing members 54 is provided to brace the lower end of the array frame assembly 13 and this second pair of bracing members is fixed to another floating lockable bracket 55. Further support is provided with a further pair of frame supports 57, the lower end of which are typically attached to the sub frame assembly. Finally, a height adjustable bracket 58 is provided, a lower end of which can be adjustably mounted to the sub frame assembly 59, and the upper end of which is fixed to the array frame assembly 13. Movement (adjustment) of this bracket 58 and particularly raising of this bracket will push the secondary axis line 56 to the right.

The arrangement enables the array frame assembly 13 to rotate or be offset relative to the sub frame assembly in a particular manner. The array frame assembly can be adjusted relative to the primary axis of rotation 15 by some rotation about the secondary axis 56 as opposed to simply tilting up or down one end of the array frame assembly. This particular offset arrangement results in one half of the array frame assembly moving above the primary axis of rotation 15 and the other half of the array frame assembly moving below the primary axis of rotation 15 this being illustrated in FIG. 3 and also being illustrated at least in FIGS. 1A and 1B.

FIG. 4A is an end view of the array frame assembly 13 in close-up and particularly illustrating the fixed locking brackets 53 and the locking pin 502 which locks into one of the openings on the sub frame assembly illustrated in FIG. 3. FIG. 4A also illustrates the V shaped frame bracing arms 54 the lower ends of which are attached to the floating lockable bracket 55 which again has a locking pin 502. FIG. 4B is a side view of the right-hand end of the array frame assembly.

FIG. 5 illustrates a slight variation to the shape of the sub frame. There is only one pair of V supporting members which are rigidly fixed to the sub frame. There is no means of moving the position of the east west axis 56 with this arrangement

FIGS. 6A, 6B and 6C illustrate another broad embodiment of the invention, the primary difference being in the configuration of the sub frame assembly. In this particular configuration, the array frame assembly 13 is supported on a generally curved assembly. The assembly comprises an upper curved member 61 which is fixed to the array frame assembly and a lower curved member 62 which sits below the upper curved member 61. Upper curved member 61 can be guided along the lower curved member 62 using a number of guide wheels 64.

Thus, the angle of inclination of the array frame assembly-13 can be adjusted relative to the sub frame assembly and, when in the desired configuration, can be locked in place by three spaced apart lockable guide members 63. The guide member 63 form a dual function which is (1) to hold the upper curved member 61 from falling off the lower curved member 62 and (2) to lock the upper curved member 61 (and therefore the array frame assembly 13) to the lower curved member 62 (part of the sub frame assembly). The locking can be done using a locking pin in a manner which may be similar to the locking arrangement described with reference to FIG. 3.

The lower curved member 62 has opposed ends which are fixed to the drive shafts 12 such that rotation of the drive shafts 12 cause rotation of the lower curved member 62 and therefore the upper curved member 61 and therefore the array face 10. The primary axis of rotation (which is the common rotation axis of drive shafts 12) is tilted to the desired angle (depending on latitude) and this is achieved using a pair of spaced apart supports 20, 19 which comprise the support frame assembly. Thus, the solar tracking apparatus as illustrated in FIG. 6A and FIG. 6B provides the same function as the solar tracking apparatus as illustrated in FIG. 3 and FIG. 5 but with a different construction.

Referring now to FIG. 7A, FIG. 7B and FIG. 8, there is illustrated a third embodiment of the invention which basically supports the array frame assembly-13 without the need of a sub frame assembly described in FIG. 3 and FIGS. 6A and 6B. In this third embodiment of the invention, array frame assembly 13 is held at the desired angle by adjustable and pivoting arms 71. The solar tracking apparatus of this third embodiment again comprises a pair of opposed generally upright supports 19, 20 on which are rotatably supported the drive shafts 12 in a manner not dissimilar to that described previously. Attached to each drive shaft 12 is one end of a pivoting arm 71. The other end of this pivoting arm is attached to another pivoting arm 71 via a pivotable elbow 72. The pivoting axis of elbow 72 is at right angles to the rotation axis of drive shaft 12. Thus, rotation of drive shaft 12 will cause the pair of pivoting arms to be swung either clockwise or anticlockwise (as the case may be). However, each pair of pivoting arms can be adjusted relative to each other (that is, the angle between each pair of pivoting arms can be adjusted) which will adjust the angle of inclination of array face assembly 10. This is clearly illustrated in FIG. 7A versus FIG. 7B where, in FIG. 7B, each pair of pivoting arms have been pivoted relative to each other to lie closer to each other compared to the angle of each pair of pivoting arms in FIG. 7A. Thus, at the obtuse angle between the pivoting arms illustrated in 7A, the inclination of the array face assembly 10 is a larger than at the acute angle between the pivoting arms illustrated in FIG. 7B where the array face assembly adopts a more horizontal orientation.

To keep the pivoting arms 71 at a desired angle, there is provided a further sliding arm 73 which is pivotly attached to one of the arm members and can be locked to the other of the arm members when the arm members are in the desired position.

Finally, a tie strap 74 can be provided to stop the array from swinging down when approaching a high inclination.

Also illustrated in FIG. 7B is the ability to provide an extension 78 to allow additional solar modules (for instance PV panels) to be mounted between the equinoxes at the warmer end of the year (when the array face assembly 10 is any more horizontal position as illustrated in FIG. 7B and therefore an extension panel 78 can be attached without striking the ground or other parts of the solar tracking apparatus).

Referring to FIG. 8, there is illustrated a slight variation to the embodiments of FIGS. 7A and 7B in that the generally upright support posts 19, 20 have been replaced by a cradle type ground support member 84. Support member 84 has a lower ground contacting part, and end parts 92,93 which extend upwardly. The upper end of each end part contains an extension bracket 83 on which a bearing 51 can be attached and the drive shaft 12 can be supported by the respective bearing 51.

In this particular embodiment, there is illustrated a mechanism to enable different solar tracking apparatus to be coupled together and driven from a single motor. This is achieved using a longitudinal drive system. The longitudinal drive system comprises an elongate torque shaft 82, one end of which is coupled to a universal joint 81 which is attached to a respective drive shaft 12. The other end of the same elongate torque shaft 82 is attached to another universal joint 81 which is attached to the drive shaft of a second solar tracking apparatus. In this manner, two or more solar tracking apparatus can be rotated using a single motor or other type of actuator by coupling the apparatus to each other using the elongate torque shaft 82.

Referring now to FIG. 10, there is illustrated in greater detail a particular type of elongate torque shaft 82. Shaft 82 can be supported for rotation by spaced apart bearings 51 each bearing being supported on a bracket 52 with the bracket being supported by elongate leg members or support structures 19, 20. The length of shaft 82 can be adjusted by a smaller diameter extendable/retractable shaft 102 which can telescope relative to the remainder of shaft 82 and which can be locked at a desired position using a locking pin 103. In this particular embodiment, it is important to note that each end of torque shaft 82 is coupled directly to the sub frame assembly or other part of the solar tracking apparatus and therefore each end of torque shaft 82 comprises the otherwise identified drive shaft 12.

FIG. 11A illustrates a slightly different type of torque shaft arrangement where the torque shaft 82 is not itself supported by bearings 51 etc. but instead interconnects the drive shafts 12 which are supported by bearings 51, the drive shafts being connected to torque shaft 82 using the universal joint 81.

FIG. 11B is similar to the embodiment illustrated in FIG. 11 A except that the bearings 51 are supported on extension bracket 83 as opposed to a supporting frame assembly 111 illustrated in FIG. 11 A.

Referring now to FIG. 9, there is illustrated a cradle type support arrangement for the solar tracking apparatus which illustrates various anchors 95 and spacers 96 to assist in anchoring the solar tracking apparatus to a support surface. FIG. 9 also illustrates pairs of guide wheels which form part of a lateral drive system best illustrated in FIG. 14 and alternatives of which are illustrated in FIGS. 13 A and 13 B.

FIG. 14 shows examples of lateral and longitudinal drive systems that in combination may allow many side by side and end on end stacked trackers to be driven by one drive motor. Two possible longitudinal drive systems are illustrated both using a common torque shaft.

FIG. 14 also illustrates a pair of side by side solar tracking apparatus interconnected by a lateral drive system which includes a reciprocating arm which can be a C section reciprocating arm 131 (illustrated in greater detail in FIG. 13 A) or an elongate rod or pipe type reciprocating arm 134 (illustrated in greater detail in FIG. 13 B). Arm 131/134 locates between opposed wheel guides 135 on the supporting cradle of each solar tracking apparatus. Arm 131/134 is connected to the sub frame assembly 59 by a connecting rod 121 which is hinged both to the arm and also to the sub frame assembly 59. Therefore, reciprocation of the arm will cause the array face assembly 10 of each solar tracking apparatus to rotate to track the sun.

Importantly, the connecting rod 121 will have a near vertical orientation when the array is in its most wind prone position and, as the guides 132,135 prevent the arms from moving either up or down, the tracker is better able to withstand wind forces than convention lateral drive systems.

Also, by having the longitudinal drive system 82 or 141 and the lateral drive system 131, it is possible for a single drive motor to turn (in a synchronised manner) the array face assembly of multiple solar tracking apparatus which may be aligned longitudinally (one behind the other) or laterally (next to each other).

Referring now to FIG. 13 A, there is illustrated one non-limiting embodiment of a particular type of lateral drive system. In this particular system, arm member 131 comprises a C section and is supported for reciprocating movement by guide wheels 132 which run on an axle 136, the axle being supported by an L-shaped bracket 133 which can be bolted to part of the support cradle 84 of a solar tracking apparatus. Connecting rod 121 is pivotly attached to the reciprocating 131 via a bracket 137 and connecting rod 121 is similarly typically connected to part of the solar tracking apparatus.

FIG. 13 B is generally similar except that the C-shaped reciprocating arm 131 has been replaced by a circular tube 134 which is guided by guide wheels 135 which rotate about a vertical axis.

FIGS. 12A and 12B illustrate how reciprocation of the lateral drive assembly can cause pivoting of the array face assembly 10 from the east to the west and from the west to the east.

The tracker has the ability to act like a tilted single axis tracker when the array frame is locked to the sub frame in the plane parallel to the longitudinal axis line. This occurs around the spring and autumn equinoxes.

Additionally, the northern and southern ends of the array frame can be offset in opposite directions to each other. One end is locked lower than the axis line so from early morning to late afternoon, this end swings through an arc under the axis line. This is balanced by the other end of the array being offset higher than the axis line which tips through an arc over the axis line when the array is turned daily over the primary longitudinal axis.

This offsetting adjustment can be carried out incrementally to keep the array face within an acceptable range from being normal to the sun. If this adjustment is carried out manually it is a simple procedure taking less than 2 minutes per array.

From the time of the autumn equinox when the array face is approximately parallel to the longitudinal axis line at midday, the tilt toward the equator is incrementally increased (equatorial end is adjusted downward and/or the polar end is adjusted upward) (FIG. 1A). On a winter's morning the array begins the day facing SE (all description refer to Northern Hemisphere) but, due to the offset, by late afternoon the array is automatically facing SW where the winter sun is setting (FIG. 2A).

Once the winter solstice passes, the equatorial end is progressively raised and/or the polar end progressively lowered until, by midsummer, in the early morning the array faces ENE, at midday the array face is close to horizontal (+ or −10 degrees) and in the afternoon the array faces WNW following the path of the sun throughout the whole day (FIG. 2B).

This represents a significant improvement over non azimuthal single axis trackers which will always face east in the morning and west in the afternoon and be us much as 30 degrees off the sun's rays at these times

Another advantage is that, in the early and late-day positions in winter, the high end of the array frame moves down and the low end swings up so that shadows thrown diagonally towards the north are shorter than for many dual and single axis trackers.

Also, the weight of the array is evenly balanced and the force required to turn the array is relatively low.

One embodiment has a common rotatable torque shaft between adjoining north-south arrays acting as part of the support structure and adding a strengthening and bracing advantage, meaning material costs can be minimized. This arrangement means that a drive unit moving one tracker will also turn one or more longitudinally connected trackers in exact phase with one another.

A complementary lateral (east-west) drive system has much better wind locking ability than existing drive systems. Using this drive system in conjunction with the longitudinal drive system enables multiple rows of trackers to be driven by one reciprocating arm.

The system also has an added benefit of being able to have additional PV modules or reflective surfaces added in the warmer months as in these times the equatorial end of the array frame is well off the ground and clear of shading from surrounding trackers.

The present invention can deliver the higher efficiency of dual axis trackers with the simplicity and cost effectiveness of single axis trackers. The invention allows the array face to closely follow the sun in all seasons and captures more solar energy in early mornings and late afternoons than most trackers.

In winter this tracker produces less diagonal self-shading than occurs for most trackers. This allows close north-south spacing of stacked arrays. So for comparable ground cover ratios, trackers can be placed further apart laterally, meaning early morning and late afternoon shading is reduced and Capacity Factor is improved.

The system is well suited to latitudes between 50 degrees north and 50 degrees south with fixed tilt settings between 16-22 degrees and the adjustable offset adding up to another + or −38 degrees. This allows a maximum tilt toward the equator in winter of up to 60 degrees at noon.

Manual adjustment is the described method of adjusting the offset of the array frame but the adjustment can easily be automated using actuators or similar. This provides the opportunity to make the adjustment more frequently (perhaps during each day) and by remote control.

The preferred embodiment has standard, one sun PV modules but the system would also work well for solar thermal system and a range of concentration systems and is also well suited to bifacial modules.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term “comprises” and its variations, such as “comprising” and “comprised of” is used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Throughout the specification and claims (if present), unless the context requires otherwise, the term “substantially” or “about” will be understood to not be limited to the value for the range qualified by the terms.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Number	Date	Country	Kind
2011900526	Feb 2011	AU	national
2011244918	Nov 2011	AU	national

Solar Tracking System

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