PRIORITY CLAIM

[0001] This application claims priority under 35 USC 119 to U.S. Provisional Patent Application No. 62/383,859, filed September 6, 2016, the entirety of which is incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

[0002] The present invention is an improved mirror panel assembly used for reflecting light to a target. More specifically, this mirror panel approach is intended for use in applications related to the field of Concentrated Solar Power (CSP), such as for heliostats and solar troughs, among others. The mirror panels are coupled to underlying support structures using pivotable (canting) hardware modules that allow the mirror panels to be pivoted and optionally laterally moveable relative to the support structure during installation and set-up.

BACKGROUND OF THE INVENTION

[0003] Solar power plants or other systems that collect and concentrate solar energy onto one or more centralized targets are well known in the art. The concentrated solar energy often is used to directly or indirectly produce electricity and/or heat. Direct conversion, often referred to as concentrating photovoltaics (CPV) occurs in some modes of practice when photovoltaic cells (also known as solar cells) serve as the target(s) to convert incident, concentrated solar energy into electricity using photovoltaic effects. Indirect conversion, often referred to as Concentrating Solar Power (CSP) occurs when thermal energy of the concentrated solar energy is used in some modes of practice to heat a working fluid, or sequence of working fluids, that in turn drives machinery such as a turbine system to generate electric power. Working fluids include steam, oil, molten salt, or the like.

[0004] U.S. Pat. Nos. 8,833,076; 8,697,271; 7,726,127; 7,299,633; and U.S. Pat. Pub. No. 2013/0081394 Al describe systems in which solar energy heats molten salt to store the thermal energy. The molten salt can store the heat for extended periods of time for later use on demand. The molten salt thus functions as a thermal battery that is charged by the sun. The molten salt in turn is used in illustrative modes of practice to heat steam that drives a turbine to generate electricity. After heating the steam, the molten salt cools down but is readily heated again, or re-charged with solar energy, by heating again using concentrated solar energy. Molten salt can be heated, used, and recharged this way many times without being consumed to any significant degree. Facilities that use molten salt in this fashion are projected to have lifespans extending for decades.

[0005] CSP systems typically rely on a field of reflecting devices that track, reflect, and collectively concentrate incident sunlight onto a solar receiver. Many types of reflecting devices are known. Examples include heliostats, parabolic dishes, trough concentrators, and the like. A CSP system often may use hundreds or even thousands of reflecting devices to concentrate solar energy.

[0006] Mirrors in most instances are a fundamental element of the reflecting devices used in CSP plants. The primary function of the mirrors is to reflect sunlight onto a target where the resultant concentrated sunlight can then be converted into other forms of useful energy, such as electricity or heat. Mirrors may have a variety of shapes, and many shapes are suitable to redirect sunlight onto a desired target. As examples of shapes, mirrors may be flat, curved in two dimensions, curved in three dimensions, faceted, and the like.

[0007] The mirrors often are supported by a suitable support structure so that the mirrors substantially maintain their shape without undue sagging, thermal deformation, or shape deformation as the mirrors articulate and are impacted by wind, moisture, age, temperature changes, and other surrounding factors. A mirror panel is a component of many different types of reflector devices. A heliostat is one type of reflector device. A heliostat is a term in the art that refers to an assembly comprising one or more mirror panel assemblies, one or more drive mechanisms attached to the mirror panel to articulate the mirror panel to track the sun, and a base structure mounted to the drive mechanism to attach the heliostat to the ground, a frame, or other fixed or moveable mounting site. Trough reflectors are another type of reflecting device.

[0008] Larger heliostats may include an array of mirror panels. Each individual mirror panel forms a facet of the overall, resultant reflecting surface. The facets in some instances may be spaced apart by a suitable gap so that adjacent mirror panels do not touch or overlap other mirror panels. Forming large heliostats from such facets allows the overall shape of the reflecting function to be optimally shaped and aimed to reflect and concentrate sunlight onto the desired target.

[0009] Heliostats whose reflecting function includes a number of individual facets typically require that the facets be individually adjusted and canted relative to the underlying heliostat support structure so that all the facets reflect their incident sunlight onto a common target. Without proper canting, the quality of the heliostat beam can be degraded, with possibly some sunlight missing the target. [00010] One existing installation technology is used at SolarReserve's Crescent Dunes project near Tonopah, Nevada. This project uses heliostats that use arrays of mirror panels to provide 115.7 m ² of reflecting surface for each heliostat. Each mirror panel, or facet, is mounted to underlying support structure using four mounting sites. Four threaded rods descend from the bottom face of the mirror panel to function as mounting studs. Hardware components on the underlying support structure couples the threaded rods to the support structure. The threaded rod fits into an enlarged aperture either in a support element itself (such as a spar or truss). In other instances, the threaded rod fits into an enlarged aperture in a mounting bracket that in turn is connected to a support element. The enlarged aperture allows the rod to be pivoted (canted) or laterally moved to achieve the desired set-up. Nuts and spherical washers are used on each side of the bracket or support element wall to position and clamp the threaded rod in position. The spherical washer components accommodate angular misalignment or angular aiming of the threaded rods.

[00011] The conventional approach is shown in Figs. 1, 2, and 3 with respect to pivotable hardware module 300. Module 300 is used to connect mounting stud 302 (shown as a threaded rod) to spar 304. Mounting stud 302 projects downward from mirror panel assembly 306 (shown in Fig. 3 but not Figs. 1 and 2), where stud 302 is threadably captured by captured nut 308. Module 300 in Figs. 1 and 2 is attached directly to spar 304. In Fig. 3, module 300 further includes mounting bracket 314. Modules of Figs. 1, 2, and 3 also include washer assembly 310 and washer assembly 312 with mounting bracket 314 (Fig. 3 only) clamped between the assemblies 310 and 312. In Figs. 1 and 2, the spar wall is clamped between the assemblies 310 and 312. Mounting stud 302 passes through enlarged aperture 311 (serving as a rod clearance hole) of spar 304 in Figs. 1 and 2 and aperture 313 of mounting bracket 314 in the form of a sheet metal bracket in Fig. 3. Washer assembles 310 and 312 fit around mounting stud 302 with a close but slideable fit in Figs. 1, 2, and 3. Jam nuts 320, 322, 324, and 326 in these Figures also are tightened against the washer assemblies 310 and 312 to adjust and secure the position and orientation of mounting stud 302.

[00012] Washer assembly 310 includes male radiused washer 316 and female radiused washer 318. The radiused surfaces of washers 316 and 318 are complementary and slideably engage to provide a radiused interface to allow mounting stud to pivot as the height of captured stud 302 is adjusted. Washer assembly 312 includes male radiused washer 328 and female radiused washer 330. The radiused surfaces of washers 328 and 330 are

complementary and slideably engage to provide a radiused interface to allow mounting stud to pivot as the height of captured stud 302 is adjusted. [00013] One problem with the conventional approach is that access to the hardware components is difficult, because the components on both sides of the attachment site must be accessed in order to install the hardware system. Some of the components are located in tight spaces that are difficult to reach, even with tool access hole 307 being provided. The system also is inconvenient to pre-assemble, so that all the parts must be carried and assembled on site. There are at least eight loose hardware parts associated with each stud 302, some of which need to be installed after the corresponding facet is aligned with the underlying support structure and properly canted. This not only complicates installation, but it takes longer to accomplish as well.

[00014] A method to achieve fast, accurate installation and canting of mirror panels is highly desirable not only to reduce assembly, installation, repair, and maintenance costs and difficulty, but also to achieve better energy collection over the life of the power facility.

SUMMARY OF THE INVENTION

[00015] The present invention provides an improved design for canting hardware components that makes it easier and faster to mount and pivot mirror facets relative to underlying support structure to aim the facet at the desired target. Instead of being forced to carry and work with a number of loose components on site, the canting hardware of the present invention can be pre-assembled into a hardware module and easily transported and installed on site. This reduces the number of loose parts during the canting process.

Installation and adjustment of each mounting stud is an easy process. In illustrative embodiments, this is achieved by rotating a single nut or other engagement feature that is easily accessed from an accessible side of the facet array. As a further advantage, the components of the hardware stack making up the module adjust automatically to

accommodate positional and angular tolerances as the nut or other engagement feature is adjusted to tune the position of the corresponding mounting stud. This makes installation fast and easy. The module allows canting adjustment in all directions if desired, although some designs can restrict the directions in which the hardware can be laterally moved and/or canted (e.g., a mounting slot restricts pivoting action or movement perpendicular to the long axis of the slot, whereas a large circular mounting hole or larger slot allows pivoting or lateral movement in any direction).

[00016] As an additional advantage, the hardware system is able to support the full weight of the facet prior to final fixation. Further, automation can be used to remotely adjust the hardware. In some embodiments, a simple rotation of a gripping feature is used to make adjustments. This rotation can be controlled through a remote interface that sends control signals to actuation components that implement the desired rotation. The remote interface can be wired or wireless.

[00017] In one aspect, the present invention relates to an assembled, canting hardware module that is used to threadably engage a threaded rod, comprising:

(a) a mounting bracket comprising a first major surface on a first side of the mounting bracket, a second major surface on a second side of the mounting bracket, and a through aperture extending from the first major surface to the second major surface;

(b) a sleeve extending through the aperture of the mounting bracket and being pivotably coupled to the mounting bracket, wherein the through aperture of the mounting bracket is oversized relative to the sleeve such that the sleeve when coupled to the mounting bracket is pivotable and rotatable within the through aperture relative to the mounting bracket, said sleeve comprising :

(i) a hollow sleeve body comprising (1) a head that projects from a first end of the sleeve body on the first side of the mounting bracket and (2) at least one engagement feature on a second end of the sleeve body on the second side of the mounting bracket that allows the sleeve to be actuated and rotated from said other side of the mounting bracket in order to cause relative axial movement between the sleeve and the threaded rod as the sleeve rotates;

(ii) a through bore extending through the sleeve body, wherein at least a portion of a surface of the through bore is threaded in a manner effective to threadably engage the threaded rod such that rotation of the sleeve causes the threaded rod to move relative to the sleeve; and wherein said head is clamped against the first major surface of the mounting bracket, and wherein a radiused interface is interposed between the clamped head and the mounting bracket; and c) at least one biased member that helps accommodate axial expansion and contraction of the hardware module as the sleeve pivots relative to the mounting bracket; and d) a second clamping element on the second side of the mounting bracket that cooperates with the head to clamp the sleeve to the bracket.

[00018] In another aspect, the present invention relates to a heliostat, comprising:

(a) a mirror panel assembly comprising at least one mirror panel comprising a top reflective surface and a bottom surface, and a frame supporting the mirror panel;

(b) an additional support structure supporting the mirror panel;

(c) at least one mounting stud coupled to the mirror panel assembly; and

(d) a hardware module according of the present invention as described above that pivotably couples the at least one mounting stud to the additional support structure.

[00019] In another aspect, the present invention relates to a method of making a heliostat, comprising:

(a) providing a mirror panel assembly comprising at least one mirror panel and a frame supporting the mirror panel;

(b) attaching a mounting stud to the mirror panel assembly;

(c) using the hardware module of the present invention as described about to pivotably attach the mounting stud to an additional support structure;

(d) adjusting the mounting stud by actuating the hardware module of claim 1 from one side of the mounting bracket of the hardware module; and

(e) locking the hardware module to fix the adjustment of the mounting stud.

BRIEF DESCRIPTION OF THE DRAWINGS

[00020] Fig. 1 is a side cross-section view of a prior art hardware module.

[00021] Fig. 2. is an exploded perspective view of the module of Fig. 1.

[00022] Fig. 3. is a side cross section view of an alternative prior art hardware module connected to a mirror panel assembly by a threaded rod.

[00023] Fig. 4 schematically shows a concentrating power system including a central tower and a field of heliostats that concentrate incident sunlight onto the tower.

[00024] Fig. 5 A is a perspective view of a heliostat used in the system of Fig. 4.

[00025] Fig. 5B is a close up view of the heliostat of Fig. 5 A. [00026] Fig. 6 is a perspective bottom view of a mirror panel assembly used in the heliostat of Fig. 5 A.

[00027] Fig. 7 is a bottom view of a mirror panel assembly used in the heliostat of Fig. 5 A.

[00028] Fig. 8 is a perspective bottom view of a mirror panel assembly used in the heliostat of Fig. 5 A attached to spars.

[00029] Fig. 9 is a side view of a mirror panel assembly used in the heliostat of Fig. 5 A attached to spars.

[00030] Fig. 10 shows a side cross section view of a hardware module of the present invention attached to a spar of Fig. 8.

[00031] Fig. 11 is an exploded perspective view of the hardware module of Fig. 10.

[00032] Fig. 12 is a perspective view of the hardware module of Fig. 10.

[00033] Fig. 13 is perspective view in cross section of the hardware module of Fig. 10.

[00034] Fig. 14 is a side cross section view showing how the hardware module of Fig. 10 pivots.

[00035] Fig. 15 is a side cross section view showing how the hardware module of Fig. 10 pivots.

[00036] Fig. 16 is a side cross section view showing how the hardware module of Fig. 10 laterally moves.

[00037] Fig. 17 is a side cross section view showing how the hardware module of Fig.107 laterally moves.

[00038] Fig. 18 shows a side cross section view of an alternative hardware module of the present invention attached to a spar of Fig. 8.

[00039] Fig. 19 is an exploded perspective view of the hardware module of Fig. 18.

[00040] Fig. 20 is a perspective view of the hardware module of Fig. 18.

[00041] Fig. 21 is perspective view in cross section of the hardware module of Fig. 18.

[00042] Fig. 22 shows how hardware modules of the present invention are attached to spars.

[00043] Fig. 23 shows how mirror panel assemblies are aligned with the hardware modules and spars of Fig. 22.

[00044] Fig. 24 shows how mirror panel assemblies are aligned with the hardware modules and spars of Fig. 22.

[00045] Fig. 25 shows a mirror panel assembly resting on a threaded hardware module of the present invention.

[00046] Fig. 26 shows how rotation of the sleeve in the threaded hardware module engages the threaded rod and moves the rod axially. [00047] Fig. 27 shows how rotation of the sleeve in the threaded hardware module engages the threaded rod and moves the rod axially.

[00048] Fig. 28 shows how a mounting stud moves freely in a threadless sleeve of a corresponding hardware module.

[00049] Fig. 29 shows how jam nuts lock the threaded rod in position I the module of Fig. 28.

[00050] Fig. 30 shows how jam nuts lock the threaded rod in position I the module of Fig. 28.

[00051] Fig. 31 shows how jam nuts secure all the hardware modules used in the installation of Figs. 22-29.

[00052] Fig. 32 shows how jam nuts secure all the hardware modules used in the installation of Figs. 22-29.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

[00053] The present invention will now be further described with reference to the following illustrative embodiments. The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather a purpose of the embodiments chosen and described is so that the appreciation and understanding by others skilled in the art of the principles and practices of the present invention can be facilitated.

[00054] Fig. 4 schematically illustrates a concentrating solar energy system 10 that incorporates principles of the present invention. System 10 includes a central tower 12 including a mast 14 and a target region 16 at the top of the mast. A field of heliostats 20 is deployed around central tower 12. The heliostats 20 redirect and concentrate incident sunlight onto target region 16. If system 10 embodies a photovoltaic solar power system (also known as concentrating photovoltaics, or CPV), target region 16 generally would include solar cells (not shown) that absorb the concentrated light and generate electricity that could then be stored for later use or distributed to one or more users or a power grid or the like. If system 10 embodies a concentrating solar power (CSP) system, used to convert thermal energy into electricity, heat, or mechanical energy (not shown), then the thermal energy generated on target region 16 may be used to heat a working fluid. The thermal energy in the heated fluid may then be used directly or indirectly to generate electricity, heat, or pressure. A CSP embodiment of system 10 is particularly useful in molten salt-based power systems such as those described in U.S. Pat. Nos. 8,833,076; 8,697,271; 7,726,127; 7,299,633; and U.S. Pat. Pub. No. 2013/0081394 Al.

[00055] Figs. 5A, 5B, 6, 7, 8, and 9 illustrate an exemplary embodiment of heliostat 20 used in system 10 of Fig. 4. Heliostat 20 includes pedestal 22 attaching heliostat 20 to the ground or other supporting surface. Rotatable vertical shaft 24 is rotatably housed inside pedestal 22. Shaft 24 rotates about a vertical, or azimuth, axis 19. Rotation of vertical shaft 24 causes array 21 to be rotatably driven about axis 19. A motor (not shown) is housed inside pedestal 22 in order to rotatably drive shaft 24. Port 25 provides access to the motor for installation, service, repair, replacement, or the like.

[00056] Yoke 26 is fixedly attached to drive shaft 24. Thus, rotation of shaft 24 causes yoke 26 to rotate about axis 19. A rotatable elevation tube 27 (also referred to as a torque tube) is rotatably mounted in bearings 28. Bearings 28, in turn, are fixedly connected to yoke 26. Lever arm 29 is connected to linear actuator 30. Linear actuator 30 drives lever arm 29 up or down as desired. Raising and lowering arm 29 rotatably drives elevation tube 27 about the elevation axis 31. Rotation of tube 27 causes array 21 to be rotatably driven about axis 31. Controller 33 is coupled by wiring 34 to motors that rotatably drive shaft 24 or actuate linear actuator 30. Elevation tube 27 is fixedly mounted to trusses 32. Trusses 32 are further coupled to spar tubes 37.

[00057] Heliostat 20 incorporates an array 21 of mirror panel assemblies 36 supported by the trusses 32 and spar tubes 37. For purposes of illustration, array 21 includes a 4 x 6 array of mirror panel assemblies 36. Many other array sizes may be used. For example, exemplary arrays include m x n arrays where m is 1 to 20 or more and n is 1 to 20 or more.

[00058] Each mirror panel assembly 36 is shown schematically in Fig. 5A as a single panel. More details of mirror panel assemblies 36 are shown in Figs. 5B, 6, 7, 8, and 9. Each mirror panel assembly 36 includes a mirror panel 38, a support frame 46, mounting pads 62, and flexures 64. Each support frame 46 supports a corresponding mirror panel 38. Each support frame 46 includes tubular support members 48 and cross members 56. Each mirror panel 38 is coupled to a corresponding underlying support frame 46. Note that each mirror panel 38 is supported by its own support frame 46.

[00059] The individual mirror panel assemblies 36 are coupled together by trusses 32 and spar tubes 37 to form the overall array 21. In practice, the mirror panel assemblies 36 typically are spaced apart from each other by a small gap 60 so that individual mirror panels 38 do not physically contact or overlap adjacent panels 38. Applicant's co-pending PCT Patent Application PCT/US2016/029767 (hereinafter the PCT Patent Application) internationally filed 28 April 2016, titled SOLAR POWER SYSTEMS USING

HELIOSTATS WITH STACKED FRAMES AND SUSPENDED MIRROR PANELS, in the names of Gregory et al., having Attorney Docket No. SLR0062WO, and claiming priority to U.S. Provisional Patent Application serial number 62/211,376, filed on August 28, 2015; U.S. Provisional Patent Application serial number 62/153,716, filed on April 28, 2015; and U.S. Provisional Patent Application serial number 62/153,723, filed on April 28, 2015, describes further details of preferred embodiments of mirror panel assembly 36 that incorporate mirror panel 38, support frame 46, mounting pads 62, and flexures 64. The PCT Patent Application and each of the three U.S. provisional patent applications are independently incorporated herein by reference in their respective entireties for all purposes.

[00060] Pivotable hardware modules of the present invention are useful to interconnect mirror panel assemblies 36 to other components of heliostat 20. An illustrative use of the pivotable hardware modules of the present invention is to connect each support frame 46 to trusses 32 and/or spar tubes 37. Cumulative attachment of the mirror panel assemblies 36 provides the desired array 21. For example, as shown best in Fig. 9, the spar tubes 37 are coupled to the cross-members 56 of support frame 46. In this embodiment, pivotable hardware modules 70 of the present invention are used to help connect spar tubes 37 to cross members 56. To accomplish this, mounting studs 58 are fixed to tubular support members 48 and project downward toward spar tubes 37. In illustrative embodiments, all or a portion of mounting studs 58 may be fully or partially threaded rods. The mounting studs 58 are captured by and secured to pivotable hardware modules 70. The pivotable hardware modules 70, in turn, are connected to spar tubes 37.

[00061] The pivoting hardware modules 70 allow each mirror panel assembly 36 to be individually installed, positioned, canted, and aimed optimally at a target region 16 on central tower 12. This, in turn, allows the overall shape of corresponding array 21 to be contoured, with each mirror panel 38 deployed as a facet of the overall array shape. For example, the overall array 21 may have a concave dish shape aimed at target region 16 to concentrate sunlight onto a smaller region of target 16. In other embodiments, array 21 may be as flat as possible with each mirror panel assembly 36 being adjusted to be in the same plane as other assemblies 36 of the array.

[00062] In use, array 21 can be articulated to be in a wide range of orientations to track the sun, for storage, for service, to avoid storm damage, or otherwise. Such articulations can cause the aim of array 21 to be horizontal, vertical, or otherwise oriented with respect to the ground. Regardless of how array 21 is oriented, the top or upward direction with respect to heliostat 20 will be taken to be along the direction of normal vector 52 that projects outward from mirror panel assembly 36, and hence outward from array 21, as shown in Fig. 9.

Similarly, the bottom or downward direction will be taken to be along the direction of normal vector 54 that projects inward from mirror panel assembly 36, and hence inward from array 21, in a direction opposite from vector 52.

[00063] Accordingly, mirror panel assembly 36 includes mirror panel 38 having top reflective surface 40, bottom surface 42, and a central region 44 on bottom surface 42 that may serve in one aspect as a reference for aligning features of mirror panel 36, such as flexures 64, as described in the PCT Patent Application in order to help accommodate thermal stresses, gravity loads, and the like.

[00064] Features of support frame 46 are shown in more detail in Figs. 5B to 9. Cross- members 56 are generally in the same plane and are deployed parallel to each other in this embodiment. Mirror panel 38 is mounted to the cross-members 56 using a plurality of flexures 64. Cross-members 56 are spaced apart from mirror panel 38 so that mirror panel is suspended above tubular support members 48 and cross members 56 by flexures 64. In this embodiment, four tubular support members 48 are shown. This number of members 48 would be suitable to support many different sizes of mirror panels 38. For example, in one mode of practice, using four members 48 that are 2.2 m long would be suitable for supporting a mirror panel that is 2.5 m long by 1.5 m wide. A greater or lesser number of tubular support members 48 can be used depending on factors such as the weight of mirror panel 38, the size of mirror panel 38, the stiffness of mirror panel 38, the environment in which mirror panel 38 is used, the thickness of the mirror panel 38, the stiffness and strength of support frame 46, and the like.

[00065] As illustrated, the cross-members 56 do not extend fully to the edges of mirror panel 38 but rather are slightly shorter so that edge portions of mirror panel 38 overhang slightly. The overhang of mirror panel 38 is short enough to avoid sagging. In one mode of practice, using members 56 with a length of 2.2 m is suitable for supporting a mirror panel 38 that overhangs members 56 by 0.05 to 0.3 m, more preferably 0.15 m.

[00066] Although cross-members 56 are shown with a rectangular cross section, a wide variety of other cross sections may be used. For example, cross-members may be round, square, ellipsoid, solid members, members with surfaces including T-slots or other features to facilitate alignment or attachment to other components, or the like.

[00067] Tubular support members 48 are generally in the same plane and are deployed parallel to each other in this embodiment. Tubular support members 48 also are spaced apart from the bottom surface 42 of mirror panel 38 so that mirror panel 38 is suspended above both members 48 and 56 by flexures 64.

[00068] Cross members 56 are stacked against and coupled to tubular support members 48 in a manner effective so that support frame 46 provides a rigid framework to support mirror panel 38. Many different strategies may be used for this connection.

Examples include screws, bolts, welding, brazing, adhesives, rivets, snap fit engagement, threaded engagement, combinations of these, and the like.

[00069] Brazing is a preferred technique for connecting cross members 56 to tubular support members 48. Brazing provides many advantages. Brazing involves substantially less heat as compared to welding. This means that brazing causes much less frame distortion of brazed assemblies. This is a very important advantage for support frame 46, which is intended to support and maintain mirror panel 38 in a flat or substantially flat-shaped or other suitable shaped condition such as a concave or trough shape. Brazing can be used on metal components that are already galvanized. This eliminates the need for post-plating or post- painting, which provides considerable manufacture savings. Hot-dip galvanizing of welded frames can induce frame distortion, which also is avoided by brazing components that are already galvanized. Brazing can also be used for dissimilar metals as well as metals that are difficult to weld without distortion or other degradation. Close tolerances between components is not required, as brazing can fill gaps and still provide strong connections. Assembly is easy because all brazing joints can be accessed from one side of the pre- positioned tubular support members 48 and cross members 56.

[00070] In this embodiment, two cross members 56 are shown. This number of would be suitable to support many different sizes of mirror panels 38. For example, in one mode of practice, using two tubular support members 48 that are 1.44 m long would be suitable for supporting a mirror panel that is 2.5 m long by 1.5 m wide. A greater or lesser number of cross members 56 can be used depending on factors such as the weight of mirror panel 38, the size of mirror panel 38, the stiffness of mirror panel 38, the stiffness and strength of support frame 46, the environment in which mirror panel 38 is used, and the like.

[00071] As illustrated, the cross members 56 do not extend fully to the edges of mirror panel 38 but rather are slightly shorter so that edge portions of mirror panel 38 overhang slightly. The overhang of mirror panel 38 is short enough to avoid sagging. In one mode of practice, using cross members 56 with a length of 1.44 m is suitable for supporting a mirror panel 38 that overhangs cross members 56 by 0.05 to 0.3 m, more preferably 0.08 m [00072] The cross members 56 are shown as having a rectangular cross section. Other cross sections may be used, as desired. Examples include cross sections that are round, square, ellipsoid, solid members, and members with surfaces including T-slots or other features to facilitate alignment or attachment to other components, or the like. Cross members 56 are hollow tubes, but solid bars of any desired cross section may be used if desired.

[00073] The PCT Patent Application describes further details of preferred

embodiments of support frame 46.

[00074] An illustrative embodiment of pivotable hardware module 70 is shown in Figs. 10 through 17. Pivotable hardware module 70 includes sleeve (in the form of a long nut) 71, mounting bracket 72, and a plurality of additional hardware elements (described further below) that help to pivotably couple the sleeve 71 to the mounting bracket 72 in a manner effective to allow module 70 and the sleeve 71 to be axially pivoted relative to the mounting bracket 72. Module 70 also includes at least one biased member (e.g., wave spring washer 76) to help accommodate axial expansion and contraction of the components of module 70 as module 70 pivots relative to the mounting bracket 72.

[00075] Sleeve 71 includes sleeve body 78 that extends from a first end 82 to a second end 84. Sleeve 71 includes a longitudinal axis 90 extending along the length of sleeve 71. Head flange 92 extends radially outward from first end 82. Head flange 92 includes a flat top surface 94 and a radiused inner surface 96. Flat top surface 94 optionally may engage a jam nut (not shown) to help secure module 70 into a desired position on a threaded embodiment of mounting stud 58. Radiused inner surface 96 slideably engages with a complementary radiused surface (described below) to help provide a radiused interface between the complementary surfaces that allows module 70 and mounting stud 58 to pivot relative to the mounting bracket 72.

[00076] In those embodiments in which the sleeve 71 threadably engages mounting stud 58, it is further desirable that the connection between the sleeve 71 and the mounting bracket 72 allows relative rotation motion between sleeve 71 and mounting bracket 72. When mounting bracket 72 is secured to spar tube 37, and hence fixed in position, rotation of sleeve 71 causes threaded rod to advance in one direction or the other along longitudinal axis 90, depending upon which direction sleeve 71 is rotated. In this fashion, module 70 allows tuning of both the canting as well as the longitudinal axis position of mounting stud 58. Preferably, the connection between the sleeve 71 and the mounting bracket 72 allows not only pivoting and rotation actions between the sleeve 71 and mounting bracket 70, but often it is desirable that the connection also allows relative lateral movement between the sleeve 71 and the mounting bracket 72. By using an oversized aperture 116 in the mounting bracket 72 to encircle the sleeve 71, the pivotable hardware module 70 easily allows pivoting action, rotation action and lateral movement to occur. When the final position of mounting stud 58 is set as desired, one or more jam nuts 128 on the mounting stud 58 can be tightened against one or both sides of module 70 in order to fix the set-up orientation. The preferred jam nut location is on the bottom of module 70 (as shown in Fig. 10, for example). A jam nut above module 70 creates some risk that it could lift the mounting stud 58 relative to sleeve 71 an amount equivalent to the backlash/slop in the threaded interface.

[00077] As shown, radiused inner surface 96 of head flange 92 is generally convex and interfaces with another complementary, generally concave radiused surface to form a pivotable interface. In other embodiments, radiused inner surface 96 may be concave to interface with a generally convex radiused surface to form the pivotable interface.

[00078] Head flange 92 provides a first clamping element attached to sleeve 71 that helps to securely clamp sleeve 71 to mounting bracket 72. The head flange 92 functions as a clamping element in a similar way that the head of a bolt cooperates with a threaded nut to clamp item(s) between the bolt head and the nut. Head flange 92 is shown as an integral part of sleeve 71 but in other embodiments may be provided by one or more separate components that are attached to sleeve 71.

[00079] Through bore 98 extends through sleeve 71 from first end 82 to second end 84. Through bore 98 comprises counter bore region 100 proximal to first end 82 to help ease entry of mounting stud 58 into through bore 98 via counter bore region 100. A cylindrical region 102 extends from counter bore 100 to second end 84. Cylindrical region 102 is matched to the size of mounting stud 58 to allow a close fit that still allows stud 58 to be inserted through the through bore 98. All or a portion of cylindrical portion 102 may be threaded to provide threaded engagement with mounting stud 58. As shown, through bore 98 is provided with threaded region 104 proximal to second end 84 to provide such threadable engagement.

[00080] In practical effect, sleeve 71 functions much like a hollow bolt or pin. The head flange 92 is analogous to the head of the bolt or pin. A fixation component can be installed on the sleeve body 78, much like the nut on the threaded shaft of a bolt, to clamp elements between the head and fixation element. From still yet another perspective, the sleeve 71 functions in a manner analogous to the action of a linear actuator. Rotation of sleeve 71 causes linear translation of the mounting stud 58 upward or downward relative to sleeve 71. In the illustrated embodiment of Figs. 10 through 17, the mounting stud 58 linearly translates but is rotationally fixed as the sleeve 71 rotates around it.

[00081] In order to position mounting stud 58 at a desired height relative to spar tube 37, sleeve 71 can be rotated in order to raise or lower the stud 58. Accordingly, it is desirable that sleeve 71 includes one or more engagement features that allow sleeve 71 to be gripped and rotated. A variety of gripping features, used singly or in combination, may be used. Examples included slots or other shaped recesses, shaped protuberances, or shaped surfaces that may be gripped by hand, with manual tools, or with power tools. As one example of such gripping features, sleeve 71 includes faces 110 extending from shoulder 108 to second end 84 to form a hexagonal-shaped tip that can be gripped with conventional sockets or wrenches. The diameter of the lower second end 84 of sleeve 71 is reduced relative to the main sleeve body 78. This makes it easier to install other components of the module 70 onto sleeve 71 during assembly of module 70.

[00082] Sleeve 71 may be formed from a wide variety of materials including metals, metal alloys, polymers, reinforced composites, ceramic, combinations of these and the like. For outdoor use and weathering, sleeve 71 desirable is formed from one or more corrosion and ultraviolet resistant materials. Desirably, the material(s) used to make sleeve 71 are compatible with the other components of module 70 and stud 58 to avoid undue galvanic corrosion effects. Specific examples of exemplary materials include stainless steel, corten steel copper, aluminum, combinations of these, and the like.

[00083] Sleeve 71 is fitted and clamped to mounting bracket 72. Mounting bracket 72 generally includes a first major surface 112 and second major surface 114. Bracket 72 includes bends 120 and 122 to provide offset bracket portions 121 and 123. The offset between bracket portions 121 and 123 is desirable to help move the top surface 82 of sleeve 71 closer to the top of spar 37. This helps to move the center of gravity of the facets closer to the elevation pivot axis to reduce gravity bias. This also helps to reduce the linear actuator output demand.

[00084] First offset bracket portion 121 includes one or more features that allow mounting bracket 72 to be attached to spar tube 37. Such attachment may be accomplished using one or more different kinds of attachment features. Examples include screws, bolts, welding, brazing, adhesives, rivets, snap fit engagement, threaded engagement, combinations of these, and the like. For purposes of illustration, bracket portion 121 includes a plurality of mounting apertures 118 so that bracket 72 is secured to spar tube 37 using blind rivets 126. [00085] Sleeve 71 is fitted to second offset bracket portion 123 through mounting aperture 116. Rather than a tight fit, aperture 116 is enlarged relative to sleeve body 78 so that sleeve 71 can be pivoted and optionally moved laterally within aperture 116. Aperture 116 can be enlarged with respect to sleeve body 78 around the full circumference of sleeve body 78 or only enlarged to allow pivoting and lateral movement in selected directions. For instance, if aperture 116 were to be a slot shape, then this could restrict pivoting and lateral movement of sleeve 71 to positions along the length of the slot. However, using a relatively large, round hole for aperture 116 as shown allows pivoting and lateral movement in any desired direction.

[00086] Pivotable hardware module 70 includes washer components on each side of mounting bracket 72. These washer assemblies help to distribute clamping forces over a wider area as sleeve 71 is attached to bracket 72. The washer assemblies also include features that allow sleeve 71 to be pivoted relative to mounting bracket 72.

[00087] A washer element 132 is positioned between head flange 92 and second offset bracket portion 123. Washer element 132 includes annular body 134 and aperture 136. Aperture 136 is large relative to sleeve body 78 to be slid easily onto sleeve body 78 during assembly of module 70. The relatively large size of aperture 136 also helps to accommodate pivoting motion of sleeve body 78. Washer element 132 includes a flat bottom face 138 to engage the flat, underlying face of second offset bracket portion 123. These complementary faces need not be flat, however, but rather can be formed with any desired, complementary contours that allows a stable connection that preferably allows a desired range (if any) of sliding motion. Washer element 132 includes a radiused upper surface 140 having a shape that complements the radiused inner surface 96 of head flange 92. The result is that a radiused interface is formed between surfaces 96 and 140. The surfaces 96 and 140 slideably engage to help allow sleeve 71 to pivot relative to mounting bracket 72.

[00088] Washer element 132 also may be referred to in the industry as a spherical washer, an alignment washer, or a radiused washer. Having a concave radiused surface in the illustrated embodiment, washer element 132 is referred to as a female type. If the radiused surface were instead to be convex to match a complementary concave surface, the convex version would be referred to as a male type. Thus, illustrative modes of the present invention use complementary male and female radiused surfaces to provide components that slideably engage in a manner effective to provide pivoting action between components.

[00089] Whereas washer element 132 is positioned on sleeve body 78 on the same side as first major face 112 of bracket 72, washer assembly 151 is positioned on sleeve body 78 on the other side of bracket 72. Bracket 72 thus is sandwiched between washer element 132 and washer assembly 151. Washer element 132 and washer assembly 151 may directly contact bracket 72 as shown. Alternatively, one or more other hardware components may be interposed. For example, one or more washers or biasing elements could be interposed, if desired.

[00090] Washer assembly 151 generally includes male radiused washer 152 and radiused female radiused washer 162. Male radiused washer 152 includes an annular body 154 with an aperture 156 that fits around sleeve body 78. Male radiused washer 152 includes a flat bottom surface 158 and a radiused upper surface 160. Female radiused washer 162 includes an annular body 164 with an aperture 168 that fits around sleeve body 78. Female radiused washer 162 includes a flat top surface 166 and a radiused lower surface 170. The radiused surfaces 160 and 170 engage to provide a radiused interface. The surfaces 160 and 170 slideably engage to help allow sleeve 71 to pivot relative to mounting bracket 72.

[00091] In a conventional nut and bolt assembly, a nut is used to help clamp items between the nut and the bolt head. Module 70 desirably includes at least one similar clamping element to help provide this clamping function. As one option to provide this kind of functionality, the external surface of sleeve body 78 can be threaded in a manner sufficient to allow a nut to be threaded into position to provide the desired clamping effect.

Alternatively, and as shown in the Figures for purposes of illustration, pivotable hardware module 70 includes a push nut retainer 142 to provide this clamping action. Push nut retainer 142 includes annular body 144 and an aperture 146 that fits snugly around sleeve body 78. The rim 148 of aperture 146 is configured with tabs 150 that are oriented at an angle relative to the main plane of annular body 144. These tabs 150 allow the push nut retainer 142 to be slid onto sleeve body 78 in one direction, but strongly resist movement in the other direction. Push nut retainer 142 is thus pushed onto sleeve body 78 until the desired degree of clamping force is achieved. As general guidelines, if the clamping force is too great, it will be more difficult than desired to pivot, rotate, and/or laterally move sleeve 71 relative to mounting bracket 72. If the clamping force is too small, then the components will be too loose and have too much play to achieve or hold the sleeve 71 in desired orientations.

[00092] The overall height of components that clamp sleeve 71 to mounting bracket 72 have a tendency to expand or contract along longitudinal axis 90 as sleeve 71 is pivoted relative to mounting bracket 72. To help accommodate this expansion and contraction, while still making sure that the assembly is tightly clamped without undue play among components, one or more biased members are included in the assembly to absorb compression forces or to expand to keep the stack tight during expansion. In the embodiment illustrated in the figures, this spring bias functionality may be provided by any suitable biasing members such as a wave washer 76 (as shown), a Belleville washer, or the like (for purposes of illustration a wave washer 76 is shown) fitted between the push nut retainer 142 and the washer assembly 151. As an alternative to this location, or in addition to this location, other convenient locations to place such a biasing member include between mounting bracket 72 and an adjacent washer or other component. Advantageously, a Belleville washer has a known spring rate/spring load as a function of the height to which the washer is compressed. This allows the desired clamping force provided between the push nut retainer 142 and flange head 92 to be easily and repeatedly established by assembling to module 70 so that the assembly has a specified height.

[00093] Advantageously, pivotable hardware module 70 can be pre-assembled, if desired, and then brought to the point of use either fully or partially assembled. Pre-assembly avoids the difficulty of having to assemble so many parts on site. The pre-assembled module 70 is easily attached to spar tube 37 at the desired location(s). Using mounting studs 58 fixed to a mirror panel assembly 36, the mirror panel assembly 36 is then easily attached to modules 70 by capturing the studs 58 in the one or more modules 70 associated with the mirror panel assembly 36. The height, orientation, and position of the threaded rods are easily adjusted by gripping the module 70 from one, accessible side via the engagement feature(s) on sleeve 71. The sleeve 71 rotates relative to mounting bracket 72, pushing the mounting stud 58 up or down (and canting it automatically) depending on the direction of rotation.

[00094] An exemplary deployment of pivotable hardware module 70 is shown in Figs. 10, 14, and 15. Pivotable hardware module 70 is bolted to spar tube 37 by blind rivets 126. A mounting stud 58 in the form of a threaded rod is threadably captured by sleeve 71. The height and angle of the rod are adjusted relative to bracket 72. Fig. 10 shows how longitudinal axis 90 of sleeve 71 is tilted away from vertical with respect to the vertical axis 39 of spar tube 37. The radiused interfaces provided by the radiused components incorporated into module 70 allows this pivoting action to occur. Jam nut 128 is tightened against second end 84 of sleeve 71 to secure the set-up. An optional jam nut (not shown) also may be used against first end 82 of sleeve 71, but often is not needed. An advantage of using only jam nut 128 on the lower, second end 84 is that the engagement feature 106 as well as jam nut 128 can be accessed and actuated as desired from one direction to make it easier for workers to install, adjust, tune, service, maintain, or otherwise work with module 70. Advantageously, module 70 is pre-assembled before attaching to spar tube 37 and mounting stud 58 to make installation easier at least in part because a worker in the field need not have to individually handle all of the individual components of module 70 to accomplish installation and set-up of the corresponding heliostat.

[00095] Figs. 14 to 17 show illustrative aspects of the pivoting and lateral positioning capabilities incorporated into module 70. The pivoting and lateral movement is facilitated by not just the radiused interfaces incorporated into module 70, but also the enlarged apertures of mounting bracket 72 and washer elements 132 and 162 that provide room for sleeve 71 to pivot and laterally move within aperture 116. In Fig. 14, module 70 and mounting stud 58 are pivoted so that second end 84 is angled away from vertical axis 39 of spar tube 37. This pivoting action is shown schematically by arrow 155. In Fig. 15, module 70 and mounting stud 58 are pivoted so that second end 84 is angled away from vertical axis 39 of spar tube 37 as shown by arrow 157. In Fig. 16, module 70 and mounting stud 58 are laterally moved away from spar tube 37 as shown by arrow 159. In Fig. 17, module 70 and mounting stud 58 are laterally moved toward spar tube 37 as shown by arrow 161. As another option (not shown), module 70 and mounting stud 58 can be both laterally moved and pivoted relative to mounting bracket 72 and spar 37, if desired. The pivoting allows angular canting of the facet assembly and accommodates any angular misalignment between the mounting stud and facet assembly. The ability to move laterally accommodates the previously mentioned pivoting, as well as any tolerances associated with the mounting stud positions relative to one another, as well as the positons of the brackets 72 on the spars.

[00096] Figs. 18 to 21 show an alternative embodiment of a pivotable hardware module 200 including sleeve 202 having through bore 204, mounting bracket 206, radiused washer 208, push nut retainer 210, washer assembly 212 including male radiused washer 214 and female radiused washer 216, bias member 218 in the form of a wave washer. Module 200 is identical to module 70 except that, unlike the threaded features of sleeve 71, the through bore 204 of sleeve 202 is not threaded. Instead, through bore 204 fits around mounting stud 220 (shown here as a threaded rod) with a sliding fit instead of a threaded engagement. That is, through bore 204 is not threaded. As a further difference, the position and orientation of mounting stud 220 and sleeve 202 are fixed laterally and pivotably with respect to mounting bracket 206 by the jam nuts above and below sleeve 202.

[00097] In practice, using a combination of the modules 70 and 220 are useful in order to mount mirror panel assemblies 36 to the spar tubes 37 and/or other heliostat components For example, in one illustrative embodiment, a mirror panel assembly 36 may be mounted to spar 37 using three modules 70 and a single module 200 (or no module 200 in some embodiments). Any more than three mounting points could over-constrain the facet, making installation more difficult. A preferred mounting design has three mounting points using module 70, since three points define a plane. Adding a fourth mounting point could have the negative consequence of possibly adding twist to the facet assembly, which could dramatically affect facet slope error. By having three adjustable mounting points

(corresponding to modules 70) and a fourth one that "goes along for the ride" (corresponding to module 200) until proper canting is achieved, and is carefully snugged down as a final step, the potential for adding twist to the facet is reduced. Another mode of practice would be to use a spherical bearing with jam nuts above and below the spherical bearing in place of module 200. However, a typical spherical bearing does not offer the lateral tolerance adjustment that module 200 does. In some embodiments, this would not be an issue when the other three points of attachment provided by modules 70 provide the required compliance.

[00098] Figs. 22 to 31 show an exemplary method as to how the two embodiments advantageously are used in combination in order to attach an illustrative mirror panel assembly 36 to one or more spar tubes 37. For purposes of illustration, a pair of spar tubes 37 are used for the installation.

[00099] In Fig. 22, a single module 200 and three modules 70 are mounted to spars 37. Although blind rivets 126 were shown above and in Fig. 19 to accomplish this, any suitable connection technique could be used. Note that the modules 70 and 200 are pre-assembled prior to attachment.

[000100] Figs. 23 to 25 show how the mirror panel assembly 36 is connected to the modules 70 and 200. Four mounting studs 58 project down from the mirror panel assembly 36 toward the modules 70 and 200. Three of these are aligned with modules 70, while the fourth mounting stud is aligned with module 200. Jam nuts 222 and 223 are pre-installed on the mounting stud 58 that will engage module 200 in Fig. 23. In Fig. 24, the mirror panel assembly is positioned so that each mounting stud is aligned to engage with a corresponding module 70 or 200, as the case may be. As shown in Fig. 25, when the mirror panel assembly 36 is lowered into modules 70 and 200, the mounting studs 58 fitting into modules 70 rest at the top of threads 104 in each sleeve 71.

[000101] Figs. 26 to 28 show how the positioning of mounting studs in modules 70 and 200 is accomplished. Using the engagement features 106 on sleeves 71, the sleeves 71 are rotated (in this embodiment, clockwise rotation as viewed from the bottom of the module 70 is used) to pull the threaded mounting studs 58 into threaded engagement with threads 104. The sleeves are rotated more to draw the mounting studs 58 further up or down as needed. The sleeves 71 and captured studs 58 automatically pivot and laterally move to accommodate this adjustment. In the meantime, the mounting stud 58 in module 200 moves freely up and down as the other three modules 70 are adjusted. Once the mirror panel is adjusted to the correct position in modules 70, optional jam nuts 128 (not shown) can be tightened against second end 84 of sleeves 71.

[000102] Figs. 29 and 30 show how the fourth adjustment point in module 200 is secured. Of the two jam nuts 222 and 223 that are pre-assembled onto the corresponding mounting stud 58, the lower nut 223 is tightened until it just comes into contact with the sleeve 202. After the desired set-up is achieved, the positioning is then secured by tightening the upper jam nut 222 against the lower jam nut 223.

[000103] Figs. 31 to 32 show how bottom jam nuts 226 are then tightened against sleeves 71 and 202 to lock the mirror panel 36 into position.

[000104] All patents, patent applications, and publications cited herein are incorporated by reference in their respective entireties for all purposes. The foregoing detailed description has been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for variations obvious to one skilled in the art will be included within the invention defined by the claims.