SUPPORT SYSTEM AND METHOD FOR TROUGH-SHAPED SOLAR ENERGY
CONCENTRATORS

FIELD OF THE INVENTION

[001] The instant invention relates generally to solar energy collectors, and more
particularly to a support system and method for trough-shaped solar energy concentrators.

BACKGROUND OF THE INVENTION

[002] Concentrating Solar Power (CSP) systems utilize mirrors to concentrate the
sun's energy onto points or lines. For instance, trough-shaped solar concentrators focus
the sun's energy onto a fluid filed tube; the hot fluid is then transferred to a more
conventional steam turbine power plant or similar system to generate electricity. One
specific and non-limiting example utilizes a trough that is parabolic in a cross section
taken in a plane that is normal to the length of the trough. With the assistance of a
tracking system, parabolic trough collectors are very efficient as they follow the
movement of the sun during the course of a day. For simplicity, the following discussion
refers to parabolic troughs and parabolic mirrors. Of course, other suitable shapes are
known.

[003] As solar energy collector apparatuses incorporating parabolic type collectors are
now being required to satisfy ever-larger energy requirements, they necessarily become
physically larger. In some apparatuses, the aggregate collector surface may typically
approach thousands of square meters. Consequently, reliable support for the large
parabolic mirrors is critical to ensure excellent performance (focus) in varying
atmospheric conditions and to guard against mirror breakage. Some of the key issues
include overall frame deflection from its own weight, and that of the attached mirrors and
wind loads. Prior art frames for solar trough designs relied on steel fabrications and
weldments or aluminum extrusions configured and joined using techniques developed in
the building construction industry. Such techniques require pre-assembly and
transportation of large frame sections, often to locations that are difficult to access, or
they require labor intensive assembly of components on-site, often under unfavorable
conditions.

[004] U.S. Patent No. 4,423,719 discloses a parabolic trough solar energy collector
that is fabricated without the need for any blind fasteners or blind fastening devices. An
integrated parabolic solar energy collector is provided which can be welded or fastened
with spot welds, seam welds, rivets, bolts or the like.

[005] U.S. Patent No. 4,135,493 discloses a parabolic trough solar energy collector
including an elongated support with a plurality of ribs secured thereto and extending
outwardly therefrom. One surface of the ribs is shaped to define a parabola and is
adapted to receive and support a thin reflecting sheet, which forms a parabolic troughshaped
reflecting surface. One or more of the collectors is adapted to be joined end-toend,
and supported for joint rotation to track the sun.

[006] U.S. Patent Application Publication No. 201 0/0050560 discloses a parabolic
trough solar energy collector frame including a plurality of chords. The frame comprises
a plurality of extruded profiles, including chord sleeves, struts and strut end pieces, each
chord sleeve having at least one chord sleeve fin, each chord sleeve positioned about one
of the chords. The frame comprises a plurality of struts, at least one of the struts having a
strut end piece having at least one strut end piece fm that connects with a chord sleeve fin
to connect the plurality of chords. The frame comprises a platform supported by the
chords and struts, on which the solar mirrors are disposed.

[007] PCT Publication WO 2010/078004 discloses a solar energy collector apparatus
comprising a solar collector panel having a parabolic shape, and a base comprising a pair
of spaced apart support frames. Each support frame has a parabolic shape, which
corresponds to the parabolic shape of the solar collector panel. Spaced apart rollers may
be positioned along an upper surface of each support frame to support the solar collector
panel. A drive mechanism may be coupled to the solar collector panel for rotation
thereof. The solar collector panel may include a pair of spaced apart rollers to ensure that
the solar collector panel rotates squarely with respect to the base.

[008] Unfortunately, even in view of the systems that have been discussed in the
preceding paragraphs, there still exists a need for a simplified support system and method
for use with trough-shaped solar energy concentrators. It would therefore be
advantageous to provide a system and a method that overcomes at least some of the
limitations of the prior art.

SUMMARY OF EMBODIMENTS OF THE INVENTION

[009] According to an aspect of at least one embodiment of the instant invention,
there is provided a support arm for a trough-shaped solar collector assembly, comprising:
a first rail having a length that extends between first and second opposite ends thereof
and having a curvature extending along the length and defining a convex side of the first
rail, the convex side forming a first open channel-structure that extends between the first
end and the second end of the first rail; a second rail having a length that extends between
first and second opposite ends thereof and having a curvature extending along the length
and defining a concave side of the second rail, the concave side forming a second open
channel-structure that extends between the first end and the second end of the second rail;
and, a plurality of web structures interconnecting the first rail and the second rail, the
plurality of web structures including a first web structure having a size that is defined
along a spacing direction between opposite edges thereof and that is larger than a size
that is defined along the spacing direction between opposite edges of a second web
structure of the plurality of web structures, wherein one of the opposite edges of the first
web structure and one of the opposite edges of the second web structure is received
within the first open channel-structure of the first rail, and the other of the opposite edges
of the first web structure and the other of the opposite edges of the second web structure
is received within the second open channel-structure of the second rail, the first web
structure disposed proximate the first ends of the first and second rails and the second
web structure disposed proximate the second ends of the first and second rails, such that
the second ends of the first and second rails are spaced more closely together than the
first ends of the first and second rails when the support arm is in an assembled condition.

[0010] According to an aspect of at least one embodiment of the instant invention,
there is provided a support arm for a trough-shaped solar collector assembly, comprising:
a first rail that is curved in a direction along a length thereof and having a concave side
for supporting a solar collector element and having a convex side that is opposite the
concave side, a first flange protruding from the convex side of the first rail and extending
along the length thereof; a second rail that is curved in a direction along a length thereof
and having a concave side, a second flange protruding from the concave side of the
second rail and extending along the length thereof, the second rail disposed in a spacedapart
relationship with the first rail such that the first and second flanges are
approximately aligned one with the other and extend one toward the other; and, a
plurality of web structures interconnecting the first rail and the second rail, the plurality
of web structures including a first web structure having a size that is defined along a
spacing direction between opposite edges thereof and that is larger than a size that is
defined along the spacing direction between opposite edges of a second web structure of
the plurality of web structures, wherein one of the opposite edges of the first web
structure and one of the opposite edges of the second web structure is fixedly secured to
the first flange of the first rail, and the other of the opposite edges of the first web
structure and the other of the opposite edges of the second web structure is fixedly
secured to the second flange of the second rail, the first web structure disposed proximate
the first ends of the first and second rails and the second web structure disposed
proximate the second ends of the first and second rails, such that the second ends of the
first and second rails are spaced more closely together than the first ends of the first and
second rails when the support arm is in an assembled condition

[0011] According to an aspect of at least one embodiment of the instant invention,
there is provided a support system for a trough-shaped solar collector assembly,
comprising: a plurality of support arms, each support arm comprising: a first rail that is
curved in a direction along a length thereof and having a concave side for supporting a
solar collector element and having a convex side that is opposite the concave side, the
convex side of the first rail forming a first web-engaging structure; a second rail that is
curved in a direction along a length thereof and having a concave side forming a second
web-engaging structure, the second rail disposed in a spaced-apart relationship with the
first rail such that the first web-engaging structure faces the second web-engaging
structure; and, a plurality of web structures fixedly secured to the first and second rails
via the first web-engaging structure and the second web-engaging structure, respectively,
including a first web structure disposed proximate the first ends of the first and second
rails and creating a first spacing therebetween, and a second web structure disposed
proximate the second ends of the first and second rails and creating a second spacing
therebetween, the second spacing smaller than the first spacing; structure-attachment
brackets mounted one each to the first ends of the first and second rails for attaching the
support arm to a structure; and, a plurality of mirror-attachment brackets mounted to the
concave side of the first rail, for securing the trough-shaped solar collector assembly to
the support arm.

[0012] According to an aspect of at least one embodiment of the instant invention,
there is provided a method for supporting a trough-shaped solar collector assembly,
comprising: for each support arm of a plurality of support arms: aligning first edge
portions of each one of a plurality of web structures with a first web engaging structure
extending along a first side of a first rail, the first rail being curved in a direction along a
length thereof and the first side being convexly curved along the length; aligning second
edge portions that are opposite the first edge portions of each one of the plurality of web
structures with a second web engaging structure extending along a first side of a second
rail, the second rail being curved in a direction along a length thereof and the first side
being concavely curved along the length; fixedly securing the first edge portions of each
one of the plurality of web structures to the first web engaging structure and fixedly
securing the second edge portions of each one of the plurality of web structures to the
second web engaging structure, so as to rigidly interconnect the first and second rails and
so that an inter-rail spacing increases between a first end of the support arm and a second
end of the support arm, the second end opposite the first end; attaching the first end of
each one of the plurality of support arms to a support structure via a pair of structure
attachment brackets mounted one each to the first rail and to the second rail at the first
end of each one of the plurality of support arms; and, attaching the trough-shaped solar
collector assembly to the plurality of support arms via attachment brackets mounted
adjacent to a second side of the first rail that is opposite the first side of the first rail.

[0013] According to an aspect of at least one embodiment of the instant invention,
there is provided a method for supporting a trough-shaped solar collector assembly, the
trough-shaped solar collector assembly extending along a length and having a collector
element array that extends outwardly a known distance in both directions from a centerline
thereof and that defines a known curvature in a direction transverse to the length,
comprising: forming a plurality of first rails each having a first length that is selected in
dependence upon the known distance, each first rail having a first web-engaging structure
defined along one side thereof; forming a plurality of second rails each having a second
length that is selected in dependence upon the known distance, each second rail having a
second web-engaging structure defined along one side thereof; sweeping each one of the
plurality of first rails to provide a curvature extending along the first length, the curvature
selected in dependence upon the known curvature of the collector element array, such
that the first web-engaging structure is defined along a side of the curved first rail that is
convex in a direction along the first length; sweeping each one of the plurality of second
rails to provide a curvature extending along the second length, the curvature selected in
dependence upon the known curvature of the collector element array, such that the webengaging
structure is defined along a side of the curved second rail that is concave in a
direction along the second length; forming a plurality of web-structures for being
disposed between a curved first rail and a curved second rail, the plurality of webstructures
being sized such that when the curved first rail and the curved second rail are
interconnected by the plurality of web structures, second ends of the curved first and
second rails are spaced more closely together than first ends of the curved first and
second rails; attaching each interconnected pair of curved first and second rails via the
first ends thereof to a central support structure that is aligned with the center-line of the
trough-shaped solar collector assembly; and, attaching the collector element array to the
interconnected pairs of curved first and second rails via attachment brackets carried by
the curved first rails.

[0014] According to an aspect of at least one embodiment of the instant invention,
there is provided a method for supporting a trough-shaped solar collector assembly,
comprising: providing a first rail having a first length, the first rail curved in a direction
along the first length and having a first flange protruding from a side thereof that is
curved convexly in a direction along the first length; providing a second rail having a
second length, the second rail curved in a direction along the second length and having a
second flange protruding from a side thereof that is curved concavely in a direction along
the second length; supporting the first rail relative to the second rail such that the first and
second flanges are approximately aligned one with the other and extend one toward the
other; overlapping a first edge portion of a web structure with the first flange and
overlapping a second edge portion of the web structure with the second flange, the first
and second edge portions spaced-apart one from the other along a spacing direction;
adjusting at least one of an extent of overlap between the first edge portion and the first
flange and an extent of overlap between the second edge portion and the second flange,
so as to define a first arrangement of the first and second rails and the web structure; and,
fixedly securing the first edge portion of the web structure to the first rail via the first
flange and fixedly securing the second edge portion of the web structure to the second
rail via the second flange while maintaining the defined first arrangement thereof.

[0015] According to an aspect of at least one embodiment of the instant invention,
there is provided afield-adjustable support system for a trough-shaped solar collector
assembly, comprising: first and second continuously curved rails for being disposed in a
spaced-apart arrangement one relative to the other, each rail having a length extending
between first and second opposite ends thereof; a web structure for being disposed
between and for interconnecting the first and second continuously curved rails, the web
structure configured for making at least three points of attachment to the first and second
continuously curved rails including at least one point of attachment to the first
continuously curved rail and one point of attachment to the second continuously curved
rail; wherein prior to fixedly securing the web structure to the first and second
continuously curved rails, at least one of the location and the orientation of the web
structure is adjustable for supporting interconnection of the first and second continuously
curved rails with different rates of convergence between a maximum inter-rail separation
between the first ends of the first and second continuously curved rails and a minimum
inter-rail separation between the second ends of the first and second continuously curved
rails.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Exemplary embodiments of the instant invention will now be described in
conjunction with the following drawings, wherein like reference numerals refer to similar
or identical parts throughout the several views, in which:

[0017] FIG. 1 is a perspective view showing a prior art support system for a troughshaped
solar concentrator assembly;

[0018] FIG. 2 is a perspective view showing a support system for a trough-shaped solar
concentrator assembly comprising a plurality of support arms, according to an
embodiment of the instant invention;

[0019] FIG. 3a is a side view of a support arm of the support system of FIG. 2;

[0020] FIG. 3b is a side view of a support arm showing a first variation of the web
structure design;

[0021] FIG. 3c is a side view of a support arm showing a second variation of the web
structure design;

[0022] FIG. 3d is a side view of a support arm showing a third variation of the web
structure design;

[0023] FIG. 4a shows a first cross-sectional profile of the first and second curved rails
of the support arm of FIGS. 3a-d;

[0024] FIG. 4b shows a second cross-sectional profile of the first and second curved
rails of the support arm of FIGS. 3a-d;

[0025] FIG. 4c shows a third cross-sectional profile of the first and second curved rails
of the support arm of FIGS. 3a-d;

[0026] FIG. 4d shows a fourth cross-sectional profile of the first and second curved
rails of the support arm of FIGS. 3a-d;

[0027] FIG. 4e shows a fifth cross-sectional profile of the first and second curved rails
of the support arm of FIGS. 3a-d;

[0028] FIG. 4f shows a sixth cross-sectional profile of the first and second curved rails
of the support arm of FIGS. 3a-d;

[0029] FIG. 4g shows a seventh cross-sectional profile of the first and second curved
rails of the support arm of FIGS. 3a-d;

[0030] FIG. 5a shows an edge portion of a web structure received within an open
channel structure that is formed along the convex side of the first rail of the support arm
of FIGS. 3a-d, the edge of the web structure spot welded to flanges protruding from the
convex side;

[0031] FIG. 5b shows an edge portion of a web structure received within an open
channel structure that is formed along the convex side of the first rail of the support an l
of FIGS. 3a-d, the edge of the web structure riveted to flanges protruding from the
convex side;

[0032] FIG. 6 shows a plurality of web structures nested together after being stamped
from a single blank;

[0033] FIG. 7 shows a structure-attachment bracket mounted to the first end of the first
curved rail of the support arm of FIGS. 3a-d;

[0034] FIG. 8 shows a mirror-attachment bracket mounted proximate to the second end
of the first curved rail of the support arm of FIGS. 3a-d;

[0035] FIG. 9 is an exploded side view showing three web structures disposed within a
common "slip plane" between the first and second rails of a support arm according to an
embodiment of the instant invention, with "vertical" adjustability indicated;

[0036] FIGS. lOa-c shows an edge portion of a web structure fixedly secured between
the flanges of one of the first and second rails of a support arm according to an
embodiment of the instant invention, at three different respective vertical positions within
the "slip plane";

[0037] FIG. 11 is an exploded side view showing three web structures disposed within
a common "slip plane" between first and second rails of a support arm according to an
embodiment of the instant invention, with "longitudinal" adjustability indicated.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0038] The following description is presented to enable a person skilled in the art to
make and use the invention, and is provided in the context of a particular application and
its requirements. Various modifications to the disclosed embodiments will be readily
apparent to those skilled in the art, and the general principles defined herein may be
applied to other embodiments and applications without departing from the scope of the
invention. Thus, the present invention is not intended to be limited to the embodiments
disclosed, but is to be accorded the widest scope consistent with the principles and
features disclosed herein. The term "vertically" should be understood to mean a
reference direction extending between the top and bottom of a drawing, and the term
"longitudinally" should be understood to mean a reference direction extending between
the left and right sides across a drawing.

[0039] In order to facilitate a better understanding of the features that are present in at
least some of the embodiments of the instant invention, a prior art system is described
herein below, with reference to FIG. 1. The prior art system 100 includes a parabolic
trough-shaped solar collector assembly including a plurality of mirror elements 102. A
plurality of support arms comprising an upper rube 104 and a lower tube 106, which are
interconnected by a plurality of lacing elements 108, are connected via inner ends of the
upper tubes 104 and of the lower tubes 106 to an elongated central support element -
torque tube 10. In particular, the upper tube 104 is connected to torque tube 1 0 via a
not illustrated upper structure- attachment bracket, and the lower tube 106 is connected to
torque tube 1 0 via lower structure-attachment bracket 112. The mirror elements 102 are
supported, one relative to another, in position above the support arms via mirrorattachment
brackets , which are mounted to the upper tube 104 at predetermined
locations along the length thereof. A torque plate 116 is provided at each of the opposite
ends of the torque tube 110 for transferring rotational motion from a not illustrated drive
mechanism to the torque tube 110, for rotating the parabolic trough-shaped solar collector
assembly about a longitudinal axis extending along the length of the torque tube 110. In
this fashion, the prior art parabolic trough-shaped solar collector tracks the movement of
the sun across the sky.

[0040] In the system 100, the upper tubes 104, the lower tubes 106, and each of the
lacing elements 108 are individually formed tubular structures. More particularly, the
shape of the upper tubes 104 and of the lower tubes 106 are created either by bending
sections of tubing that have been cut to length, or by welding together shorter tubular
sections with angled ends so as to build the upper and lower tubes 4 and 106 with the
desired shape. Further, each one of the individual lacing elements 108 must be cut to a
specified length, to within very close tolerance, and must be positioned precisely during
the process of assembling the supports arms. Very close tolerance and precise
positioning of the lacing elements 108 is necessary, since each lacing element must be
welded at one end to the upper tube 04 and at the other end to the lower tube 106. Even
relatively small cutting errors or positioning errors can result in difficulty during the
fixturing and assembly of the components of the support arms. Further, since a large
number of individual tubular structures are welded together to form the support arms, the
assembly of system 100 winds up being a very labor-intensive process.

[0041] When a trough-shaped solar collector is to be installed using the system 100 of
FIG. 1, a plurality of the support arms must be preassembled and then transported to the
installation site, or they must be assembled at the installation site often under adverse
working conditions. In either case, the resulting support system 100 is excessively heavy
and often provides unsatisfactory rigidity. In addition, the system 100 cannot be easily
modified for supporting trough-shaped solar collectors of varying size and/or shape, since
any such modification involves redesigning a large number of components in order to
ensure that all of the components fit together sufficiently closely to allow for welding
together to form the support arms.

[0042] Referring now to FIG. 2, shown is a perspective view of a support system for
supporting a trough-shaped solar concentrator assembly, according to an embodiment of
the instant invention. The system 200 includes a parabolic trough-shaped solar collector
assembly, including a plurality of mirror elements 202. A plurality of support arms, each
comprising a first rail 204 and a second rail 206 interconnected by a plurality of web
structures 208a-d, are coupled via inner ends of the first rails 204 and of the second rails
206 to an elongated central support element - torque tube 210. In particular, the first rail
204 is connected to torque tube 210 via a not illustrated upper structure attachment
bracket, and the second rail 206 is connected to torque tube 210 via a lower structure
attachment bracket 2 . The mirror elements 202 are supported one-relative to another
above the support arms via mirror attachment brackets 214, which are mounted to the
first rail 204 at predetermined locations along the length thereof. A torque plate 216 is
provided at each of the opposite ends of the torque tube 2 0 for transferring rotational
motion from a not illustrated drive mechanism to the torque tube 210, for rotating the
parabolic trough-shaped solar collector assembly about a longitudinal axis extending
along the length of the torque tube 210. In this fashion, the supported trough-shaped
solar concentrator assembly tracks the movement of the sun across the sky.

[0043] Referring now to FIG. 3a, shown is a side view of a support arm of the support
system that is shown in FIG. 2. By way of a specific and non-limiting example, each one
of the first rail 204 and the second rail 206 in FIG. 3a has a cross-sectional profile of the
type that is shown in greater detail in FIG. 4a. In particular, a pair of flanges protrudes
from, and extends along the entire length of, the convexly curved side of the first rail 204
and the concavely curved side of the second rail 206. The pair of flanges, which includes
a first flange 402 and a second flange 404, provides spaced-apart facing surfaces that
define an open channel structure for receiving therebetween the edge portions of the
plurality of web structures 208a-d. Additionally, the surfaces of the first flange 402 and
of the second flange 404 facilitate attachment of the web structures 208a-d to the first rail
204 and to the second rail 206, such as for instance by spot-welding or by riveting. The
enlarged section that is shown within the dashed-oval in FIG. 3a shows, in greater detail,
a pair of rivets 300 securing the web structure 208b to the flanges 402/404 of the second
rail 206.

[0044] Structure mounting brackets 2 and 218 are fixedly secured to the second rail
206 and to the first rail 204, respectively, such as by riveting or spot-welding. In
addition, a plurality of mirror attachment brackets 214 are mounted at predetermined
locations along the length of the first rail 204, such as by riveting or spot welding. In the
specific example that is shown in FIG. 3a, a total of four mirror attachment brackets 214
are shown. Optionally, a number of mirror attachment brackets 214 greater than or less
than four is provided, in dependence upon the length of the first rail 204, the size of the
trough-shaped solar collector being supported, etc.

[0045] Referring still to FIG. 3a, each one of the plurality of web structures 208a-d is
shaped and sized differently than the other ones of the plurality of web structures 208a-d.
The particular shape and size of each of the plurality of web structures 208a-d is
determined based on the requirements of a particular application. In general terms, the
web structure 208a is larger in a spacing direction than the web structure 208b, which is
larger in the spacing direction than the web structure 208c, which is larger in the spacing
direction than the web structure 208d. When in the assembled condition, first ends of the
first and second rails 204 and 206, respectively, are spaced farther apart than second ends
of the first and second rails 204 and 206, respectively.

[0046] According to at least one embodiment, the first and second rails 204 and 206,
respectively, and the plurality of web structures 208a-d are fabricated from the same
material, such as for instance high-strength steel. In this case, the plurality of web
structures 208a-d is attached to the first and second rails 204 and 206, respectively, by
one of welding, riveting or another suitable coupling mechanism.

[0047] According to at least one embodiment, the first and second rails 204 and 206,
respectively, and the plurality of web structures 208a-d are fabricated from different
materials. For instance, the first and second rails 204 and 206, respectively, are
fabricated from high-strength steel and the plurality of web structures 208a-d is fabricated
from aluminum or an alloy thereof, or from a composite material, etc. Some examples of
composite materials include steel/plastic/steel sandwich materials or steel/paper/steel
sandwich materials. Depending on the specific combination of materials that is used, the
plurality of web structures 208a-d is attached to the first and second rails 204 and 206,
respectively, using a suitable one of welding, riveting or another suitable coupling
mechanism.

[0048] FIG. 3b shows a side view of a support arm showing a first variation of the web
structure design. In particular, the "V" shaped web structures 208a-c and the end web
structure 208d of FIG. 3a are replaced by an extended "M" shaped web structure 302a
and an extended "N" shaped web structure 302b. Attachment of the web structures 302a
and 302b to the first and second rails 204 and 206, respectively, is accomplished as
described above.

[0049] FIG. 3c shows a side view of a support arm showing a second variation of the
web structure design. In particular, the "V" shaped web structures 208a-c and the end
web structure 208d of FIG. 3a are replaced by a single extended "M" shaped web
structure 304. Attachment of the web structure 304 to the first and second rails 204 and
206, respectively, is accomplished as described above.

[0050] FIG. 3d shows a side view of a support arm showing a third variation of the web
structure design. In particular, the "V" shaped web structures 208a-c and the end web
structure 208d of FIG. 3a are replaced by a plurality of straight-section web structures
306, 308 and 310 and a generally arc-shaped web structure 312. Attachment of the web
structures 306, 308, 310 and 312 to the first and second rails 204 and 206, respectively, is
accomplished as described above.

[0051] FIG. 4a shows a first cross-sectional profile of the curved first and second rails,
204 and 206, respectively, of the support arm of FIGS. 3a-d. In particular, the profile
includes a substantially rectangular portion 400 with two flanges 402 and 404 extending
away from one side thereof. The two flanges 402 and 404 define an open channel
structure 406 therebetween for receiving edge portions of the web structures 208a-d. In
addition, the flanges 402 and 404 provide surfaces for fixedly securing the edge portions
of the web structures 208a-d, such as by spot welding as shown in FIG. 5a or by riveting
as shown in FIG. 5b. By way of a specific and non-limiting example, the first rails 204
and the second rails 206 are roll formed to produce non-curved rails having the profile
shown that is shown in FIG. 4a. After roll forming the profile, curvature is added to the
non-curved rails in a sweep box, such that the flanges 402 and 404 are arranged along a
resulting convexly curved side of the first rails 204 and along a resulting concavely
curved side of the second rails 206. The dimensions indicated in FIG. 4a are provided by
way of a specific and non-limiting example. In practice, the actual dimensions of the rail
profile are selected based on the specific requirements of a particular application.
Optionally, the edge portions of one or more of the web structures that are shown in
FIGS. 3b-c are received between the two flanges 402 and 404 in place of the web
structures 208a-d.

[0052] FIG. 4b shows a second cross-sectional profile of the first and second curved
rails of the support arm of FIGS. 3a-d. In particular, the profile includes a substantially
triangular portion 410 with two flanges 412 and 414 extending away from one apex
thereof. The two flanges 412 and 414 define an open channel structure 416 therebetween
for receiving edge portions of the web structures 208a-d.

[0053] FIG. 4c shows a third cross-sectional profile of the first and second curved rails
of the support ann of FIGS. 3a-d. In particular, the profile includes a substantially
rectangular portion 420 with a single flange 422 extending away from a central portion of
one side thereof. A small gap 424 adjacent to the flange 422 may be welded for added
rigidity after the profile is formed. The flange 422 provides a surface for fixedly securing
the edge portions of the web structures 208a-d, such as by spot welding or by riveting,
etc. Optionally, one or more of the web structures that are shown in FIGS. 3b-c are
fixedly secured to the flange 422 in place of the web structures 208a-d.

[0054] FIG. 4d shows a fourth cross-sectional profile of the first and second curved
rails of the support arm of FIGS. 3a-d. In particular, the profile includes a substantially
rectangular portion 430 with a single flange 432 extending away from an edge portion of
one side thereof. A small gap 434 adjacent to the flange 432 may be welded for added
rigidity after the profile is fonned. The flange 432 provides a surface for fixedly securing
the edge portions of the web structures 208a-d, such as by spot welding or by riveting,
etc. Optionally, one or more of the web structures that are shown in FIGS. 3b-c are
fixedly secured to the flange 422 in place of the web structures 208a-d.

[0055] FIG. 4e shows a fifth cross-sectional profile of the first and second curved rails
of the support arm of FIGS. 3a-d. In particular, the profile includes a substantially righttriangular
portion 440 with a single flange 442 extending away from an apex thereof. A
small gap 444 adjacent to the flange 442 may be welded for added rigidity after the
profile is formed. The flange 442 provides a surface for fixedly securing the edge
portions of the web structures 208a-d, such as by spot welding or by riveting, etc.
Optionally, one or more of the web structures that are shown in FIGS. 3b-c are fixedly
secured to the flange 422 in place of the web structures 208a-d.

[0056] FIG. 4f shows a sixth cross-sectional profile of the first and second curved rails
of the support arm of FIGS. 3a-d. In particular, the profile includes a substantially square
or rectangular closed portion 450. The closed portion 450 optionally is roll formed and
closed with a seam weld, or is extruded or hydroformed. A single flange 452 is fixedly
secured to one side of the closed portion 450 and projects away therefrom at substantially
a right angle. As is shown at 454 in FIG. 4f, the flange 452 is welded to the one side of
the closed portion 450. The single flange extends along the length of the curved rail and
provides a surface for fixedly securing the edge portions of the web structures 208a-d,
such as by spot welding or by riveting, etc. Optionally, one or more of the web structures
that are shown in FIGS. 3b-c are fixedly secured to the flange 422 in place of the web
structures 208a-d.

[0057] FIG. 4g shows a fifth cross-sectional profile of the first and second curved rails
of the support arm of FIGS. 3a-d. In particular, the profile includes a substantially
circular closed portion 460. The closed portion 460 optionally is roll formed and closed
with a seam weld, or is extruded or hydroformed. A single flange 462 is fixedly secured
to the closed portion 460 and projects away therefrom at substantially a right angle. As is
shown at 464 in FIG. 4g, the flange 462 is welded to the one side of the closed portion
460. The single flange extends along the length of the curved rail and provides a surface
for fixedly securing the edge portions of the web structures 208a-d, such as by spot
welding or by riveting, etc. Optionally, one or more of the web structures that are shown
in FIGS. 3b-c are fixedly secured to the flange 422 in place of the web structures 208a-d.

[0058] FIG. 5a shows an end view in which an edge portion of a web structure 208a-d
is received within an open channel structure that is formed along the convex side of the
first rail 204 of the support arm of FIGS. 3a-d. Spot welds 500 fixedly secure the edge of
the web structures 208a-d to surfaces of the flanges 402 and 404, which flanges protrude
from the convex side of the first rail 204. Optionally, one or more of the web structures
that are shown in FIGS. 3b-c are fixedly secured to the flanges 402 and 404 in place of
the web structures 208a-d.

[0059] FIG. 5b shows an end view in which an edge portion of a web structure 208a-d
is received within an open channel structure that is formed along the convex side of the
first rail 204 of the support arm of FIGS. 3a-d. A rivet 502 fixedly secure the edge of the
web structures 208a-d to surfaces of the flanges 402 and 404, which flanges protrude
from the convex side of the first rail 204. Optionally, one or more of the web structures
that are shown in FIGS. 3b-c are fixedly secured to the flanges 402 and 404 in place of
the web structures 208a-d.

[0060] FIG. 6 shows a plurality of web structures, in this specific example web
structures 208a-d, nested together after being stamped from a single blank. By way of a
specific and non-limiting example, steel rule dies are used to stamp out the plurality of
web structures 208a-d in a single press. Of course, different web structure shapes may be
stamped in a similar fashion.

[0061] FIG. 7 shows enlarged detail of a structure attachment bracket 218, which is
mounted to the first end of the first curved rail 204 of the support arm of FIGS. 3a-d. In
the instant example, the structure attachment bracket 218 is secured to the first curved rail
204 using a pair of rivets 700, one of which is not illustrated in FIG. 7. The structure
attachment bracket 218 includes through-holes 702 for receiving a mechanical fastener
when the support arm is mounted to a support structure, such as for instance torque tube
210 of FIG. 2. By way of a specific and non-limiting example, the structure attachment
bracket 218 is fabricated from steel.

[0062] FIG. 8 shows a mirror attachment bracket mounted proximate to the second end
of the first curved rail of the support arm of FIGS. 3a-d. In the instant example, the
mirror attachment bracket 214 is secured to the first curved rail 204 using a pair of rivets
800, one of which is not illustrated in FIG. 8. The mirror attachment bracket 214
includes a through-hole 802 for receiving a mechanical fastener when the trough-shaped
solar collector is mounted thereto. By way of a specific and non-limiting example, the
structure attachment bracket 214 is fabricated from steel.

[0063] The first rail 204, the second rail 206, the web structures such as 208a-d, the
structure-attachment brackets 212 and 218 and the mirror-attachment brackets 214 may
be fixtured to facilitate assembly. The system 200 that is illustrated in FIG. 2 is then
assembled by attaching a plurality of support arms along both sides of the torque tube
210, via the structure-attachment brackets 212 and 218. The system 200 provides the
same stiffness as the system 100 but with reduced weight, or alternatively the system 200
provides improved stiffness relative to the system 100 with the same weight. Of course,
increased stiffness results in reduced deflection such that the structure is deformed to a
lesser extent under the influence of gravity as the system tracks the sun during the course
of the day, or when the system is subjected to high wind loads. Reduced deflection
results in improved optical characteristics and accordingly higher efficiency.

[0064] The system of FIG. 2 is more modular and more customizable than the prior art
system of FIG. 1. For instance, a system for supporting larger trough-shaped collector
systems may be fabricated simply by roll-forming longer first and second rails 204 and
206, respectively, and by stamping a plurality of web structures that provide a support
arm with desired inter-rail spacing between an inner end that is attached to a central
torque tube, or to another suitable support structure, and an outer end that is opposite the
inner end. Optionally, two or more rail portions are joined together in an end-to-end
fashion to form a first rail and two or more rail portions are joined together in an end-toend
fashion to form a second rail. In this way, the same tool may be used to roll-form
rails that are nearly two times the length of the first and second rails 204 and 206,
respectively, of the system 200.

[0065] FIGS. 9, lOa-c and 11 illustrate the different degrees of adjustability that are
present in the system of FIG. 2. As discussed above, the flanges (e.g. 402 and 404)
protruding from the convex and concave sides of the first and second rails 204 and 206,
respectively, provide surfaces for attaching the web structures to the rails. For instance,
the edges of the web structures are overlapped with the flanges of the first and second
rails, and are fixedly secured thereto by riveting, by welding, by toggle locking or by
another suitable method. As is shown in FIGS. 9, lOa-c and 11 each of the web
structures (for clarity, only the web structures 208a-c are shown in FIGS. 9 and 11) are
disposed within a common plane, referred to as a "slip plane" 900. Prior to fixedly
securing the web structures to the flanges of the first and second rails, an extent of
overlap between the edge portions of the web structures and the flanges, and/or the
location of the web structures along the length of the rails, can be adjusted within
predetermined limits by moving the web structures vertically (indicted by the doubleheaded
arrows in FIG. 9) and/or longitudinally (indicted by the double-headed arrows in
FIG. 11), within "slip plane" 900.

[0066] Adjusting the extent of the overlap between the edge portions of the web
structures and the first and second flanges, and/or adjusting the location of the web
structures along the length of the rails, provides sufficient flexibility to compensate for
cutting errors in the manufacture of the web structures, or to allow for a relatively small
amount of modification to the geometry of the support arm. For instance, it may be
possible to modify a particular support arm design by roll forming first and second rails
that are up to at least 10% longer than the design calls for, and still be able to successfully
interconnect the first and second rails without making any modifications to the web
structures. In particular, the web structures may be attached to the longer rails with an
increased spacing between the web structures compared to the spacing that is provided in
the particular design, such as by adjusting the web structures longitudinally within "slip
plane" 900. Additionally, the height of the support arm may be varied by adjusting the
web structures "vertically" within "slip plane" 900, as is shown in greater detail in FIGS.
lOa-c. Each one of FIGS. lOa-c shows the edge portion of one of the web structures
208a-d fixedly secured to the flanges 402 and 404 via spot welds 500. In FIG. 10a, a
support arm of intermediate height is formed in which the edge portions of the web
structures 208a-d do not extend past the flanges 402 and 404 into the substantially
rectangular portion 400 of the rail. In FIG. 10b, a support arm of lesser height relative to
10a is formed in which the edge portions of the web structures 208a-d extend past the
flanges 402 and 404 and into the substantially rectangular portion 400 of the rail. In FIG.
10c, a support arm of greater height relative to 10a is formed in which the edge portions
of the web structures 208a-d extend only partially into the opening that is formed
between the flanges 402 and 404.

[0067] The web structures may also be adjusted rotationally, relative to the rails, as
required in order to facilitate making three points of attachment to the first and second
rails 204 and 206, including at least one point of attachment to the first rail 204 and at
least one point of attachment to the second rail 206. The prior art system 100 does not
support this type of modification, including field modifications even under adverse
conditions, since each of the lacing elements 108 must be cut precisely to length in order
to be welded to the upper and lower tubes 104 and 106, respectively. There is no
adjustable overlap in the prior art system 100, since the ends of the lacing elements 108
are butted up against the surfaces of the upper and lower tubes 104 and 106, respectively,
and welded thereto.

[0068] Additionally, since the web structures that are shown in FIGS. 3a-d may be
secured to the flanges of the rails by riveting, instead of by welding, the use of different
materials such as for instance steel for the rails and aluminum or composite materials for
the web structures, is supported. The use of lightweight materials results in substantial
weight reduction compared to the prior art system 100 of FIG. 1. Further, the use of flat
web structures, such as the ones that are shown in FIGS. 3a-d, instead of the prior art
tubular members results in additional weight reduction compared to the system 100 of
FIG. 1. Alternatively, greater rigidity is achieved in the system 200 compared to the
system 100 of the same weight.

[0069] Numerous other embodiments may be envisaged without departing from the
scope of the instant invention.

CLAIMS

What is claimed is:

1. A support arm for a trough-shaped solar collector assembly, comprising:
a first rail having a length that extends between first and second opposite ends
thereof and having a curvature extending along the length and defining a convex side of
the first rail, the convex side forming a first open channel-structure that extends between
the first end and the second end of the first rail;
a second rail having a length that extends between first and second opposite ends
thereof and having a curvature extending along the length and defining a concave side of
the second rail, the concave side forming a second open channel-structure that extends
between the first end and the second end of the second rail; and,
a plurality of web structures interconnecting the first rail and the second rail, the
plurality of web structures including a first web structure having a size that is defined
along a spacing direction between opposite edges thereof and that is larger than a size
that is defined along the spacing direction between opposite edges of a second web
structure of the plurality of web structures,
wherein one of the opposite edges of the first web structure and one of the opposite edges
of the second web structure is received within the first open channel-structure of the first
rail, and the other of the opposite edges of the first web structure and the other of the
opposite edges of the second web structure is received within the second open channelstructure
of the second rail, the first web structure disposed proximate the first ends of the
first and second rails and the second web structure disposed proximate the second ends of
the first and second rails, such that the second ends of the first and second rails are spaced
more closely together than the first ends of the first and second rails when the support
arm is in an assembled condition.

2. A support arm according to claim 1, comprising first and second substantially parallel
flanges protruding from the convex side of the first rail, and comprising third and fourth
substantially parallel flanges protruding from the concave side of the second rail, the first
and second flanges cooperatively defining the first open-channel structure and the third
and fourth flanges cooperatively defining the second open-channel structure.

3. A support arm according to claim 2, wherein the one of the opposite edges of the first
and second web structures are coupled to the first rail via at least a surface of the first and
second flanges, and the other of the opposite edges of the first and second web structures
are coupled to the second rail via at least a surface the third and fourth flanges.

4. A support arm according to any one of claims 1 to 3, wherein each one of the first and
second web structures is coupled to the first and second rails via at least three points of
attachment including at least one point of attachment to one of the first and second rails
and at least one point of attachment to the other one of the first and second rails.

5. A support arm according to any one of claims 1 to 4, wherein the first and second web
structures are fixedly secured to the first and second rails by welding.

6. A support arm according to any one of claims 1 to 4, wherein the first and second web
structures are fixedly secured to the first and second rails by riveting.

7. A support arm according to any one of claims 1 to 4, wherein the first and second web
structures are toggle-locked to the first and second rails.

8. A support arm according to any one of claims 1 to 7, wherein the first and second rails
are fabricated from a first material and the plurality of web structures is fabricated from a
second material.

9. A support arm according to any one of claims 1 to 8, wherein the first and second rails
are fabricated from steel and the plurality of web structures is fabricated from aluminum
or an alloy thereof.

10. A support arm according to any one of claims 1 to 8, wherein the first and second
rails are fabricated from steel and the plurality of web structures is fabricated from a
composite material.

11. A support arm according to any one of claims 1 to 10, comprising a structuremounting
bracket coupled to the first end of each one of the first and second rails for
attaching the support arm to a structural support member.

12. A support arm according to any one of claims 1 to , comprising a plurality of
collector-mounting brackets coupled to the first rail for attaching the trough-shaped solar
collector assembly to the support arm.

13. A support arm according to claim 12, wherein the structure-mounting brackets are for
attaching the support arm to a central torque tube of the trough-shaped solar collector
assembly.

14. A support arm for a trough-shaped solar collector assembly, comprising:
a first rail that is curved in a direction along a length thereof and having a concave
side for supporting a solar collector element and having a convex side that is opposite the
concave side, a first flange protruding from the convex side of the first rail and extending
along the length thereof;
a second rail that is curved in a direction along a length thereof and having a
concave side, a second flange protruding from the concave side of the second rail and
extending along the length thereof, the second rail disposed in a spaced-apart relationship
with the first rail such that the first and second flanges are approximately aligned one
with the other and extend one toward the other; and,
a plurality of web structures interconnecting the first rail and the second rail, the
plurality of web structures including a first web structure having a size that is defined
along a spacing direction between opposite edges thereof and that is larger than a size
that is defined along the spacing direction between opposite edges of a second web
structure of the plurality of web structures,
wherein one of the opposite edges of the first web structure and one of the opposite edges
of the second web structure is fixedly secured to the first flange of the first rail, and the
other of the opposite edges of the first web structure and the other of the opposite edges
of the second web structure is fixedly secured to the second flange of the second rail, the
first web structure disposed proximate the first ends of the first and second rails and the
second web structure disposed proximate the second ends of the first and second rails,
such that the second ends of the first and second rails are spaced more closely together
than the first ends of the first and second rails when the support arm is in an assembled
condition.

15. A support arm according to claim 14, wherein each one of the first and second web
structures is coupled to the first and second rails via at least three points of attachment
including at least one point of attachment to one of the first and second rails and at least
one point of attachment to the other one of the first and second rails.

16. A support arm according to claim 4 or 15, wherein the first and second web
structures are fixedly secured to the first and second flanges by welding.

17. A support arm according to claim 14 or 15, wherein the first and second web
structures are fixedly secured to the first and second flanges by riveting.

18. A support arm according to claim 14 or 15, wherein the first and second web
structures are toggle-locked to the first and second flanges.

19. A support arm according to any one of claims 14 to 18, wherein the first and second
rails are fabricated from a first material and the plurality of web structures is fabricated
from a second material.

20. A support arm according to any one of claims 14 to 19, wherein the first and second
rails are fabricated from steel and the plurality of web structures is fabricated from
aluminum or an alloy thereof.

21. A support arm according to any one of claims 14 to 20, wherein the first and second
rails are fabricated from steel and the plurality of web structures is fabricated from a
composite material.

22. A support arm according to any one of claims 14 to 21, comprising a structuremounting
bracket coupled to the first end of each one of the first and second rails for
attaching the support a n to a structural support member.

23. A support arm according to any one of claims 4 to 22, comprising a plurality of
collector-mounting brackets coupled to the first rail for attaching the trough-shaped solar
collector assembly to the support arm.

24. A support ann according to claim 22, wherein the structure-mounting brackets are for
attaching the support arm to a central torque tube of the trough-shaped solar collector
assembly.

25. A support arm according to any one of claims 14 to 24, wherein the first flange is
integrally formed with the first rail and the second flange is integrally formed with the
second rail.

26. A support arm according to any one of claims 1 to 24, wherein the first flange is
fixedly secured along the length of the convex side of the first rail and the second flange
is fixedly secured along the length of the concave side of the second rail.

27. A support arm according to claim 26, wherein the first flange is welded to the convex
side of the first rail and the second flange is welded to the concave side of the second rail.

28. A support system for a trough-shaped solar collector assembly, comprising:
a plurality of support arms, each support arm comprising:
a first rail that is curved in a direction along a length thereof and having a
concave side for supporting a solar collector element and having a convex side
that is opposite the concave side, the convex side of the first rail forming a first
web-engaging structure;
a second rail that is curved in a direction along a length thereof and having
a concave side forming a second web-engaging structure, the second rail disposed
in a spaced-apart relationship with the first rail such that the first web-engaging
structure faces the second web-engaging structure; and,
a plurality of web structures fixedly secured to the first and second rails
via the first web-engaging structure and the second web-engaging structure,
respectively, including a first web structure disposed proximate the first ends of
the first and second rails and creating a first spacing therebetween, and a second
web structure disposed proximate the second ends of the first and second rails and
creating a second spacing therebetween, the second spacing smaller than the first
spacing;
structure-attachment brackets mounted one each to the first ends of the
first and second rails for attaching the support arm to a structure; and,
a plurality of mirror-attachment brackets mounted to the concave side of
the first rail, for securing the trough-shaped solar collector assembly to the
support a l .

29. A support system according to claim 28, wherein the first web-engaging structure
comprises a first open channel-structure that extends along the convex side between a
first end of the first rail and a second end that is opposite the first end of the first rail, and
wherein the second web-engaging structure comprises a second open channel-structure
that extends along the concave side between a first end of the second rail and a second
end that is opposite the first end of the second rail.

30. A support system according to claim 29, comprising first and second substantially
parallel flanges protruding from the convex side of the first rail, and comprising second
and third substantially parallel flanges protruding from the concave side of the second
rail, the first and second flanges cooperatively defining the first open-channel structure
and the second and third flanges cooperatively defining the second open-channel
structure.

31. A support system according to claim 28, wherein the first web-engaging structure
comprises a first flange that extends along the convex side between a first end of the first
rail and a second end that is opposite the first end of the first rail, and wherein the second
web-engaging structure comprises a second flange that extends along the concave side
between a first end of the second rail and a second end that is opposite the first end of the
second rail.

32. A support system according to any one of claims 28 to 31, wherein each one of the
first and second web structures is coupled to the first and second rails via at least three
points of attachment.

33. A support system according to any one of claims 28 to 31, wherein the first and
second web structures are fixedly secured to the first and second rails by welding.

34. A support system according to any one of claims 28 to 31, wherein the first and
second web structures are fixedly secured to the first and second rails by riveting.

35. A support system according to any one of claims 8 to 31, wherein the first and
second web structures are toggle-locked to the first and second rails.

36. A support system according to any one of claims 28 to 35, wherein the first and
second rails are fabricated from a first material and the plurality of web structures is
fabricated from a second material.

37. A support system according to any one of claims 28 to 36, wherein the first and
second rails are fabricated from steel and the plurality of web structures is fabricated
from aluminum or an alloy thereof.

38. A support system according to any one of claims 28 to 36, wherein the first and
second rails are fabricated from steel and the plurality of web structures is fabricated
from a composite material.

39. A method for supporting a trough-shaped solar collector assembly, comprising:
for each support arm of a plurality of support arms:
aligning first edge portions of each one of a plurality of web structures
with a first web engaging structure extending along a first side of a first rail, the
first rail being curved in a direction along a length thereof and the first side being
convexly curved along the length;
aligning second edge portions that are opposite the first edge portions of
each one of the plurality of web structures with a second web engaging structure
extending along a first side of a second rail, the second rail being curved in a
direction along a length thereof and the first side being concavely curved along
the length;
fixedly securing the first edge portions of each one of the plurality of web
structures to the first web engaging structure and fixedly securing the second edge
portions of each one of the plurality of web structures to the second web engaging
structure, so as to rigidly interconnect the first and second rails and so that an
inter-rail spacing increases between a first end of the support arm and a second
end of the support arm, the second end opposite the first end;
attaching the first end of each one of the plurality of support arms to a support
structure via a pair of structure attachment brackets mounted one each to the first rail and
to the second rail at the first end of each one of the plurality of support arms; and,
attaching the trough-shaped solar collector assembly to the plurality of support
anns via attachment brackets mounted adjacent to a second side of the first rail that is
opposite the first side of the first rail.

40. A method according to claim 39, wherein fixedly securing comprises welding.

41. A method according to claim 39, wherein fixedly securing comprises riveting.

42. A method according to claim 39, wherein fixedly securing comprises toggle locking.

43. A method according to any one of claims 39 to 42, wherein aligning first edge
portions comprises inserting the first edge portions into an open channel structure that is
formed along the first side of the first rail, and wherein aligning second edge portions
comprises inserting the second edge portions into an open channel structure that is
formed along the first side of the second rail.

44. A method according to any one of claims 39 to 42, wherein aligning first edge
portions comprises overlapping the first edge portions with a flange that is formed along
and that protrudes from the first side of the first rail, and wherein aligning second edge
portions comprises overlapping the second edge portions with a flange that is formed
along and that protrudes from the first side of the second rail.

45. A method for supporting a trough-shaped solar collector assembly, the trough-shaped
solar collector assembly extending along a length and having a collector element array
that extends outwardly a known distance in both directions from a center-line thereof and
that defines a known curvature in a direction transverse to the length, comprising:
forming a plurality of first rails each having a first length that is selected in
dependence upon the known distance, each first rail having a first web-engaging structure
defined along one side thereof;
forming a plurality of second rails each having a second length that is selected in
dependence upon the known distance, each second rail having a second web-engaging
structure defined along one side thereof;
sweeping each one of the plurality of first rails to provide a curvature extending
along the first length, the curvature selected in dependence upon the known curvature of
the collector element array, such that the first web-engaging structure is defined along a
side of the curved first rail that is convex in a direction along the first length;
sweeping each one of the plurality of second rails to provide a curvature
extending along the second length, the curvature selected in dependence upon the known
curvature of the collector element array, such that the web-engaging structure is defined
along a side of the curved second rail that is concave in a direction along the second
length;
forming a plurality of web-structures for being disposed between a curved first
rail and a curved second rail, the plurality of web-structures being sized such that when
the curved first rail and the curved second rail are interconnected by the plurality of web
structures, second ends of the curved first and second rails are spaced more closely
together than first ends of the curved first and second rails;
attaching each interconnected pair of curved first and second rails via the first
ends thereof to a central support structure that is aligned with the center-line of the
trough-shaped solar collector assembly; and,
attaching the collector element array to the interconnected pairs of curved first
and second rails via attachment brackets carried by the curved first rails.

46. A method for supporting a trough-shaped solar collector assembly, comprising:
providing a first rail having a first length, the first rail curved in a direction along
the first length and having a first flange protruding from a side thereof that is curved
convexly in a direction along the first length;
providing a second rail having a second length, the second rail curved in a
direction along the second length and having a second flange protruding from a side
thereof that is curved concavely in a direction along the second length;
supporting the first rail relative to the second rail such that the first and second
flanges are approximately aligned one with the other and extend one toward the other;
overlapping a first edge portion of a web structure with the first flange and
overlapping a second edge portion of the web structure with the second flange, the first
and second edge portions spaced-apart one from the other along a spacing direction;
adjusting at least one of an extent of overlap between the first edge portion and
the first flange and an extent of overlap between the second edge portion and the second
flange, so as to define a first arrangement of the first and second rails and the web
structure; and,
fixedly securing the first edge portion of the web structure to the first rail via the
first flange and fixedly securing the second edge portion of the web structure to the
second rail via the second flange while maintaining the defined first arrangement thereof.

47. A method according to claim 46, wherein the first rail includes a third flange disposed
parallel to the first flange so as to define a first space therebetween and the second rail
includes a fourth flange disposed parallel to the second flange so as to define a second
space therebetween, wherein overlapping a first edge portion of the web structure
comprises inserting the first edge portion into the first space, and wherein overlapping the
second edge portion of the web structure comprises inserting the second edge portion into
the second space.

48. A method according to claim 46 or 47, wherein fixedly securing comprises one of
welding and riveting.

49. A field-adjustable support system for a trough-shaped solar collector assembly,
comprising:
first and second continuously curved rails for being disposed in a spaced-apart
arrangement one relative to the other, each rail having a length extending between first
and second opposite ends thereof;
a web structure for being disposed between and for interconnecting the first and
second continuously curved rails, the web structure configured for making at least three
points of attachment to the first and second continuously curved rails including at least
one point of attachment to the first continuously curved rail and one point of attachment
to the second continuously curved rail;
wherein prior to fixedly securing the web structure to the first and second
continuously curved rails, at least one of the location and the orientation of the web
structure is adjustable for supporting interconnection of the first and second continuously
curved rails with different rates of convergence between a maximum inter-rail separation
between the first ends of the first and second continuously curved rails and a minimum
inter-rail separation between the second ends of the first and second continuously curved
rails.

50. A field-adjustable support system for a trough-shaped solar collector assembly
according to claim 49, comprising a first web engaging structure disposed along one side
of the first continuously curved rail and a second web structure disposed along one side
of the second continuously curved rail, wherein the first web engaging structure is
aligned with and facing the second web engaging structure when the first and second
continuously curved rails are disposed in the spaced-apart arrangement.
1. A field-adjustable support system for a trough-shaped solar collector assembly
according to claim 50, wherein the first web engaging structure comprises a first open
channel structure and the second web engaging structure comprises a second open
channel structure.

52. A field-adjustable support system for a trough-shaped solar collector assembly
according to claim 51, wherein the first web engaging structure comprises a first pair of
substantially parallel flanges spaced one from the other so as to define the first open
channel structure therebetween, and wherein the second web engaging structure
comprises a second pair of substantially parallel flanges spaced one from the other so as
to define the second open channel structure therebetween.

53. A field-adjustable support system for a trough-shaped solar collector assembly
according to claim 50, wherein the first web engaging structure comprises a first flange
and the second web engaging structure comprises a second flange.