U.S. patent application number 17/178593 was filed with the patent office on 2021-06-10 for solar tracker stow system and method.
The applicant listed for this patent is SUNFOLDING, INC.. Invention is credited to Kyle Douglass Betts, Joshua Earle Erickson, Dan Goldwater, Jeffrey Charles Lamb, Leila Madrone, James Vincent Nolan, IV, Vincent Domenic Romanin, Matthew N. Schneider, Eric Preston Lien Suan.
Application Number | 20210175841 17/178593 |
Document ID | / |
Family ID | 1000005405954 |
Filed Date | 2021-06-10 |
United States Patent
Application |
20210175841 |
Kind Code |
A1 |
Betts; Kyle Douglass ; et
al. |
June 10, 2021 |
SOLAR TRACKER STOW SYSTEM AND METHOD
Abstract
A solar tracker system having one or more solar trackers that
each include one or more panels and one or more actuators coupled
to the one or more panels, the one or more actuators having a first
and second vessel; and an electronic control unit configured to
inflate the first vessel with fluid from a fluid source and
configured to separately inflate the second vessel with fluid from
the fluid source. The electronic control unit is configured to
determine that a stow event is present based on a first set of
environmental data obtained from an environmental sensor that
indicates environmental conditions pose a threat to the one or more
solar trackers, and in response to determining that the stow event
is present, actuate the one or more panels toward a stow
configuration target angle by at least inflating the first or
second vessels with fluid from the fluid source.
Inventors: |
Betts; Kyle Douglass; (San
Francisco, CA) ; Erickson; Joshua Earle; (Oakland,
CA) ; Goldwater; Dan; (Amherst, MA) ; Lamb;
Jeffrey Charles; (San Francisco, CA) ; Madrone;
Leila; (San Francisco, CA) ; Nolan, IV; James
Vincent; (San Francisco, CA) ; Romanin; Vincent
Domenic; (San Francisco, CA) ; Schneider; Matthew
N.; (Sierra Madre, CA) ; Suan; Eric Preston Lien;
(Baltimore, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUNFOLDING, INC. |
San Francisco |
CA |
US |
|
|
Family ID: |
1000005405954 |
Appl. No.: |
17/178593 |
Filed: |
February 18, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15955519 |
Apr 17, 2018 |
10951159 |
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17178593 |
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62486335 |
Apr 17, 2017 |
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62486369 |
Apr 17, 2017 |
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62486377 |
Apr 17, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02S 20/32 20141201;
F15B 2211/8855 20130101; F15B 15/10 20130101; G01S 3/7861 20130101;
F15B 2211/6303 20130101; F24S 30/425 20180501; F15B 2211/7656
20130101; F24S 2030/115 20180501; B25J 9/142 20130101; F15B
2211/6309 20130101; F24S 2030/12 20180501; Y02E 10/50 20130101;
F15B 2211/7107 20130101; H02S 20/10 20141201; Y02E 10/47 20130101;
H01L 31/042 20130101; F24S 50/20 20180501 |
International
Class: |
H02S 20/32 20060101
H02S020/32; F24S 50/20 20060101 F24S050/20; H01L 31/042 20060101
H01L031/042; F24S 30/425 20060101 F24S030/425; H02S 20/10 20060101
H02S020/10; F15B 15/10 20060101 F15B015/10; B25J 9/14 20060101
B25J009/14 |
Goverment Interests
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH
[0002] This invention was made with Government support under
contract number DE-AR0000330 awarded by DOE, Office of ARPA-E. The
Government has certain rights in this invention.
Claims
1. A solar tracker system comprising: a plurality of solar
trackers, with each solar tracker including: a plurality of
photovoltaic cells disposed in a common plane and extending along a
first length having a first axis, the plurality of photovoltaic
cells coupled to rails that extend along a second axis that is
parallel to the first axis; a plurality of actuators coupled to the
rails and configured to collectively rotate the plurality of
photovoltaic cells, the plurality of actuators disposed along a
common third axis that is parallel to the first and second axis,
each of the plurality of actuators having: a bottom plate; a top
plate coupled to the rails; and a first and second bellows
extending between and coupled to the top plate and bottom plate; a
wind sensor; a row controller operably coupled to and configured to
control the plurality of solar trackers, the row controller
comprising: a shared pneumatic fluid source; and a pneumatic
circuit having one or more pneumatic lines coupled of a first set
of bellows including the first bellows of the plurality of
actuators and one or more pneumatic lines coupled of a second set
of bellows including the second bellows of the plurality of
actuators, the first and second sets of bellows being mutually
exclusive; and an active electronic pneumatic control unit
configured to collectively inflate the first set of bellows with
fluid from the shared pneumatic fluid source via the pneumatic
circuit and configured to separately inflate the second set of
bellows with fluid from the shared pneumatic fluid source via the
pneumatic circuit, the active electronic pneumatic control unit
configured for: actuating the plurality of photovoltaic cells
toward a first determined target ideal angle by at least inflating
the first or second set of bellows with fluid from the shared
pneumatic fluid source via the pneumatic circuit, the actuating
based at least in part on determining that a determined difference
between a first determined current angle of the plurality of
photovoltaic cells and the first determined target ideal angle of
the plurality of photovoltaic cells is outside of a tolerance
range, determining that a stow event is present based at least in
part on a first set of wind velocity data obtained from the wind
sensor including wind velocity data above a defined threshold and
for a defined time period that indicates wind conditions being
present that pose a threat to at least one of the plurality of
solar trackers, the threat to at least one of the plurality of
solar trackers including the wind conditions potentially causing
physical damage to the at least one of the plurality of solar
trackers, in response to determining that the stow event is
present, actuating the plurality of photovoltaic cells toward a
stow configuration target angle by at least inflating the first or
second set of bellows with fluid from the shared pneumatic fluid
source via the pneumatic circuit, upon reaching the stow
configuration target angle, inflating the first and second set of
bellows to an equilibrium to rigidly fix the plurality of
photovoltaic cells at the stow configuration target angle, while
the plurality of photovoltaic cells are rigidly fixed at the stow
configuration target angle, determining that the stow event is no
longer present based at least in part on a second set of wind
velocity data obtained from the wind sensor including wind velocity
data below a defined threshold and for a defined time period that
indicates wind conditions being present that no longer pose the
threat to the plurality of solar trackers, and in response to
determining that the stow event is no longer present, actuating the
plurality of photovoltaic cells toward a second determined target
ideal angle by at least inflating the first or second set of
bellows with fluid from the shared pneumatic fluid source via the
pneumatic circuit, the actuating based at least in part on
determining that a determined difference between a second
determined current angle of the plurality of photovoltaic cells and
the second determined target ideal angle of the plurality of
photovoltaic cells is outside of the tolerance range.
2. The solar tracker system of claim 1, further comprising
determining that a stow event is present based at least in part on
one or more of: a detected power loss; a detected failure of
pneumatic elements; a detected failure of one or more sensors; and
a detected failure of a control system.
3. The solar tracker system of claim 1, wherein the stow
configuration target angle is an angle of the plurality of
photovoltaic cells between two maximum tilt position angles where
the plurality of solar trackers are forced against a respective
hard stop at the maximum tilt position angles.
4. The solar tracker system of claim 1, wherein the active
electronic pneumatic control unit is configured to operate the
plurality of actuators at a minimum operating pressure when no wind
is present and configured to dynamically increase stiffness of the
plurality of actuators in response to increasing wind speed by
dynamically increasing operating pressure of the plurality of
actuators.
5. A solar tracker system comprising: a plurality of solar
trackers, with each solar tracker including one or more solar
panels and a plurality of actuators coupled to the one or more
solar panels, each of the plurality of actuators having first and
second elastic vessels; a wind sensor; and an electronic control
unit configured to collectively inflate a first set of the first
elastic vessels with fluid from a fluid source and configured to
separately inflate a second set of the second elastic vessels with
fluid from the fluid source, the electronic control unit configured
to: determine that a stow event is present based at least in part
on a first set of wind speed data obtained from the wind sensor
that indicates wind conditions being present that pose a threat to
at least one of the plurality of solar trackers, the threat to at
least one of the plurality of solar trackers including the wind
conditions potentially causing physical damage to the at least one
of the plurality of solar trackers, in response to determining that
the stow event is present, actuate the one or more solar panels
toward a stow configuration target angle by at least inflating the
first or second set of elastic vessels with fluid from the fluid
source, and upon reaching the stow configuration target angle,
inflate the first and second set of elastic vessels to rigidly fix
the one or more solar panels at the stow configuration target
angle.
6. The solar tracker system of claim 5, wherein the determining
that a stow event is present based at least in part on the first
set of wind speed data obtained from the wind sensor that indicates
wind conditions being present that pose the threat to at least one
of the plurality of solar trackers includes determining that the
first set of wind speed data indicates wind speed above a defined
wind speed threshold and for a defined time period.
7. The solar tracker system of claim 5, wherein the electronic
control unit is further configured to: while the one or more solar
panels are fixed at the stow configuration target angle,
determining that the stow event is no longer present based at least
in part on a second set of wind speed data obtained from the wind
sensor including wind speed data below a defined threshold and for
a defined time period that indicates wind conditions being present
that no longer pose the threat to the plurality of solar
trackers.
8. The solar tracker system of claim 7, wherein the electronic
control unit is further configured to: in response to determining
that the stow event is no longer present, actuating the one or more
solar panels toward a determined target ideal angle by at least
deflating or inflating the first or second set of elastic vessels
with fluid from the fluid source, the actuating based at least in
part on determining that a determined difference between a
determined current angle of the one or more solar panels and the
determined target ideal angle of the one or more solar panels is
outside of a tolerance range.
9. The solar tracker system of claim 5, wherein the electronic
control unit is further configured to: determine that an alert
should be sent to a user regarding wind conditions based at least
in part on determining that a first set of wind speed data
indicates wind speed above a defined wind speed threshold and for a
defined time period; and send an alert to the user regarding wind
speed proximate to the solar tracker system potentially causing
physical damage to the at least one of the plurality of solar
trackers.
10. A solar tracker system comprising: one or more solar trackers,
with each solar tracker including one or more panels and one or
more actuators coupled to the one or more panels, each of the one
or more actuators having a first vessel and a second vessel; and an
electronic control unit configured to inflate the first vessel with
fluid from a fluid source and configured to separately inflate the
second vessel with fluid from the fluid source, the electronic
control unit configured to: determine that a stow event is present
based at least in part on a first set of environmental data
obtained from an environmental sensor that indicates environmental
conditions being present that pose a threat to the one or more
solar trackers, and in response to determining that the stow event
is present, actuate the one or more panels toward a stow
configuration target angle by at least inflating the first or
second vessels with fluid from the fluid source.
11. The solar tracker system of claim 10, wherein the electronic
control unit is further configured to: upon reaching the stow
configuration target angle, inflate the first and second vessels to
fix the one or more panels at the stow configuration target
angle.
12. The solar tracker system of claim 10, wherein the threat to the
at least one of the one or more solar trackers including the
environmental conditions potentially causing physical damage to the
one or more solar trackers.
13. The solar tracker system of claim 10, wherein the environmental
sensor comprises a wind sensor.
14. The solar tracker system of claim 10, wherein first set of
environmental data comprises wind speed data or wind velocity
data.
15. The solar tracker system of claim 10, wherein the determining
that the stow event is present is based at least in part on a first
set of wind speed data obtained from a wind sensor that indicates
wind conditions being present that pose the threat to the one or
more solar trackers, and wherein determining that the stow event is
present further includes determining that the first set of wind
speed data indicates wind speed above a defined wind speed
threshold.
16. The solar tracker system of claim 10, wherein the electronic
control unit is further configured to: while the one or more panels
are fixed at the stow configuration target angle, determining that
the stow event is no longer present based at least in part on a
second set of environmental data obtained from the environmental
sensor; and in response to determining that the stow event is no
longer present, actuating the one or more panels toward a
determined target ideal angle by at least deflating or inflating
the first or second vessel, the actuating based at least in part on
determining that a determined difference between a determined
current angle of the one or more panels and the determined target
ideal angle of the one or more panels is outside of a tolerance
range.
17. The solar tracker system of claim 10, further comprising
determining that a stow event is present based at least in part on
one or more of: a detected power loss; a detected failure of a
pneumatic element; a detected failure of one or more sensors; and a
detected failure of a control system.
18. The solar tracker system of claim 10, wherein the stow
configuration target angle is an angle of the one or more panels
between two maximum tilt position angles where the one or more
solar trackers are forced against a respective hard stop at the
maximum tilt position angles.
19. The solar tracker system of claim 10, wherein the electronic
control unit is configured to operate the one or more actuators at
a minimum operating pressure when no wind is present and configured
to dynamically increase stiffness of the one or more actuators in
response to increasing wind speed by dynamically increasing
operating pressure of the one or more actuators.
20. The solar tracker system of claim 10, wherein the electronic
control unit is further configured to: determine that an alert
should be sent to a user regarding environmental conditions based
at least in part on a second set of data from the environmental
sensor; and send an alert to the user regarding environmental
conditions proximate to the solar tracker system potentially
causing physical damage to the one or more solar trackers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/955,519, filed Apr. 17, 2018, entitled
"SOLAR TRACKER CONTROL SYSTEM AND METHOD" having attorney docket
number 0105935-005US0, which is a non-provisional of and claims
priority to U.S. Provisional Applications entitled "PNEUMATIC
ACTUATOR SYSTEM AND METHOD" and "PNEUMATIC ACTUATION CIRCUIT SYSTEM
AND METHOD" and "SOLAR TRACKER CONTROL SYSTEM AND METHOD"
respectively and having attorney docket numbers 0105935-003PR0 and
0105935-004PR0 and 0105935-005PR0 and respectively having
application Nos. 62/486,335, 62/486,377 and 62/486,369. These
applications are hereby incorporated herein by reference in their
entirety and for all purposes.
[0003] This application is related to U.S. Non-Provisional
application Ser. No. 15/955,044 and 15/955,506, filed Apr. 17, 2018
entitled "PNEUMATIC ACTUATOR SYSTEM AND METHOD" and "PNEUMATIC
ACTUATION CIRCUIT SYSTEM AND METHOD" respectively, and having
attorney docket numbers 0105935-003US0 and 0105935-004US0. These
applications are hereby incorporated herein by reference in their
entirety and for all purposes.
[0004] This application is also related to U.S. application Ser.
No. 15/012,715, filed Feb. 1, 2016, which claims the benefit of
U.S. provisional patent application 62/110,275 filed Jan. 30, 2015.
These applications are hereby incorporated herein by reference in
their entirety and for all purposes.
[0005] This application is also related to U.S. application Ser.
Nos. 14/064,070 and 14/064,072, both filed Oct. 25, 2013, which
claim the benefit of U.S. Provisional Application Nos. 61/719,313
and 61/719,314, both filed Oct. 26, 2012. All of these applications
are hereby incorporated herein by reference in their entirety and
for all purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIGS. 1a and 1b illustrate a respective top perspective and
bottom perspective view of a solar tracker in accordance with
various embodiments.
[0007] FIG. 2 illustrates a side view of a solar tracker.
[0008] FIG. 3 illustrates a side view of an actuator in accordance
with one embodiment, which comprises a V-shaped bottom plate, a
planar top-plate, and a set of bellows that are disposed between
the top and bottom plates and surrounded by a set of washers.
[0009] FIG. 4 illustrates an example of a solar tracking system
that includes a row controller that controls a plurality of rows of
solar trackers.
[0010] FIG. 5 is an exemplary illustration of a set of rows,
including a first tracker and second tracker, with each tracker
comprising a plurality of actuators disposed along a common axis
and with each actuator comprising a first and second bellows.
[0011] FIG. 6 is a block diagram of elements of a solar tracking
system that includes a row controller and a first and second solar
tracker.
[0012] FIG. 7 illustrates an example of a tracker tracking the
position of sun throughout the day as the sun moves through the
sky.
[0013] FIG. 8a illustrates an example of a tracker being in a
non-ideal position relative to the sun and FIG. 8b illustrates
moving the tracker to an ideal position with the tracker axis being
coincident with the center of the sun.
[0014] FIG. 9 illustrates an example method of controlling one or
more solar trackers to match the angle or position of the sun.
[0015] FIG. 10 illustrates a state diagram associated with
controlling one or more solar trackers.
[0016] FIG. 11 illustrates a tracking window that can be used by
the when controlling one or more solar trackers.
[0017] FIG. 12 illustrates a method of identifying a stow event and
generating a stow in one or more tracker.
[0018] FIG. 13 illustrates a method 1300 of level-calibrating a
solar tracker in accordance with an embodiment.
[0019] FIG. 14 is a block diagram of elements of a solar tracking
system that includes an array controller, a first and second row
controller and four solar trackers.
[0020] FIG. 15 illustrates an example embodiment of a row
controller featuring a "stow on power loss" function.
[0021] It should be noted that the figures are not drawn to scale
and that elements of similar structures or functions are generally
represented by like reference numerals for illustrative purposes
throughout the figures. It also should be noted that the figures
are only intended to facilitate the description of the preferred
embodiments. The figures do not illustrate every aspect of the
described embodiments and do not limit the scope of the present
disclosure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] FIGS. 1a and 1b illustrate respective top perspective and
bottom perspective views of a solar tracker 100 in accordance with
various embodiments. FIG. 2 illustrates a side view of the solar
tracker 100. As shown in FIGS. 1a, 1b and 2, the solar tracker 100
can comprise a plurality of photovoltaic cells 103 disposed along a
length having axis X.sub.1 and a plurality of pneumatic actuators
101 configured to collectively move the array of photovoltaic cells
103. As shown in FIG. 1b, the photovoltaic cells 103 are coupled to
rails 102 that extend along parallel axes X.sub.2, which are
parallel to axis X.sub.1. Each of the plurality of actuators 101
extend between and are coupled to the rails 102, with the actuators
101 being coupled to respective posts 104. As shown in FIG. 2, the
posts 104 can extend along an axis Z, which can be perpendicular to
axes X.sub.1 and X.sub.2 in various embodiments.
[0023] As shown in FIG. 2, and discussed in more detail herein, the
actuators 101 can be configured to collectively tilt the array of
photovoltaic cells 103 based on an angle or position of the sun,
which can be desirable for maximizing light exposure to the
photovoltaic cells 103 and thereby maximizing electrical output of
the photovoltaic cells 103. In various embodiments, the actuators
101 can be configured to move the photovoltaic cells 103 between a
plurality of configurations as shown in FIG. 2, including a neutral
configuration N where the photovoltaic cells 103 are disposed along
axis Y that is perpendicular to axis Z. From the neutral
configuration N, the actuators 101 can be configured to move the
photovoltaic cells 103 to a first maximum tilt position A, to a
second maximum tilt position B, or any position therebetween. In
various embodiments, the angle between the neutral configuration N
and the maximum tilt positions A, B can be any suitable angle, and
in some embodiments, can be the same angle. Such movement can be
used to position the photovoltaic cells 103 toward the sun,
relative to an angle of the sun, to reflect light toward a desired
position, or the like.
[0024] In one preferred embodiment as shown in FIGS. 1a and 1b, a
solar tracker 100 can comprise a plurality of photovoltaic cells
103 that are collectively actuated by four actuators 101 disposed
along a common axis. However, in further embodiments, a solar
tracker 100 can comprise any suitable number of actuators 101
including one, two, three, four, five, six, seven, eight, nine,
ten, fifteen, twenty, fifty, one hundred, or the like. Similarly,
any suitable number of photovoltaic cells 103 can be associated
with a solar tracker 100 in further embodiments. Additionally,
while photovoltaic cells 103 are shown in example embodiments
herein, in further embodiments, actuators 101 can be used to move
various other objects or structures, including mirrors, reflectors,
imaging devices, communications devices, and the like.
[0025] FIG. 3 illustrates a side view of an actuator 101 in
accordance with one embodiment. As shown in the example of FIG. 3,
the actuator 101 comprises a V-shaped bottom plate 310, a planar
top-plate 330, and a set of bellows 300 that are disposed between
the top and bottom plates 330, 310 and surrounded by a set of
washers 350. The washers 350 are coupled to a hub assembly 370 that
extends between the bottom and top plates 310, 330, with the hub
assembly 370 defined by a plurality of stacked hub units 373.
[0026] The example embodiment of FIG. 3 illustrates the actuator
101 in a neutral configuration N (see FIG. 2), where the top plate
330 extends along axis Y, which is perpendicular to axis Z in the
neutral configuration N. However, as discussed herein, the top
plate 330 can be configured to tilt to the left and right (or east
and west as discussed herein) based on selective inflation and/or
deflation of the bellows 300. Components of an actuator 101 can
comprise various suitable materials, including metal (e.g., steel,
aluminum, iron, titanium, or the like), plastic or the like. In
various embodiments, metal parts can be coated for corrosion
prevention (e.g., hot dip galvanized, pre galvanized, or the
like).
[0027] A row controller 380 can be operably coupled with bellows
300 of the actuator via pneumatic lines 390. More specifically, an
east bellows 300E can be coupled to a pneumatic circuit 382 of the
row controller 380 via an east pneumatic line 390E. A west bellows
300W can be coupled to the pneumatic circuit 382 of the row
controller 380 via a west pneumatic line 390W. A pneumatic control
unit 384 can be operably coupled to the pneumatic circuit 382,
which can control the pneumatic circuit 382 to selectively inflate
and/or deflate the bellows 300 to move the top plate 330 of the
actuator 101 to tilt photovoltaic cells 103 coupled to the top
plate 330.
[0028] For example, as described herein, bellows 300 of an actuator
101 can be inflated and/or deflated which can cause the bellows 300
to expand and/or contract along a length of the bellows 300 and
cause movement of washers 350 surrounding the bellows 300. Such
movement of the washers 350 can in turn cause rotation, movement or
pivoting of the hub units 373 of the hub assembly 370. Such
pivoting of hub units 373 of the hub assembly 370 can be generated
when a solar tracker 100 is moving between a neutral position N and
the maximum tilt positions A, B as shown in FIG. 2.
[0029] As shown in FIG. 3, a bellows 300 can comprise a convoluted
body defined by repeating alternating valleys 302 and peaks 304
extending between a first and second end of the bellows 300. In
various embodiments, a bellows 300 can be generally cylindrical
about a central axis along which the bellows 300 extend. In various
embodiments, the bellows 300 and portions thereof can have one or
more axes of symmetry about a central axis. For example, in various
embodiments, the convolutions of the bellows 300 can have circular
radial symmetry and/or axial symmetry about a central axis between
the first and second ends or at least a portion thereof. However,
as shown in FIG. 3, the bellows 300 can be held within an actuator
101 in a curved configuration such that the portion of the bellows
300 proximate to the hub assembly 370 is compressed compared to the
portion of the bellows that is distal from the hub assembly
370.
[0030] In various embodiments, the bellows 300 can be configured to
expand along the length of the bellows 300 when fluid is introduced
into the hollow bellows 300 or when the bellows 300 are otherwise
inflated. Accordingly, the bellows 300 can be configured to
contract along the length of the bellows 300 when fluid is removed
from the hollow bellows 300 or when the bellows 300 are otherwise
deflated.
[0031] Where bellows 300 are configured to expand lengthwise based
on increased pressure, fluid or inflation and configured to
contract lengthwise based on decreased pressure, fluid or
inflation, movement of the photovoltaic cells 103 via one or more
actuators 101 can be achieved in various ways. For example,
referring to the example of FIG. 3, rotating the photovoltaic cells
103 west (i.e., to the right in this example) can be achieved via
one or more of the following:
TABLE-US-00001 TABLE 1 Examples of Actions to Rotate Actuator 101
West East Bellows 300E West Bellows 300W Result Increase Pressure
Maintain Pressure Rotate West Increase Pressure Reduce Pressure
Rotate West Maintain Pressure Reduce Pressure Rotate West Decrease
Pressure Decrease Pressure More Than Rotate West East Bellows 300E
Increase Pressure Increase Pressure Less Than Rotate West East
Bellows 300E
[0032] Referring again to the example of FIG. 3, rotating the
photovoltaic cells 103 east (i.e., to the left in this example) can
be achieved via one or more of the following:
TABLE-US-00002 TABLE 2 Examples of Actions to Rotate Actuator 101
East East Bellows 300E West Bellows 300W Result Maintain Pressure
Increase Pressure Rotate East Reduce Pressure Increase Pressure
Rotate East Reduce Pressure Maintain Pressure Rotate East Decrease
Pressure More Than Decrease Pressure Rotate East West Bellows 300W
Increase Pressure Less Than Increase Pressure Rotate East West
Bellows 300W
[0033] Accordingly, in various embodiments, by selectively
increasing and/or decreasing the amount of fluid within bellows
300E, 300W, the top plate 330 and photovoltaic cells 103 can be
actuated to track the location or angle of the sun.
[0034] While various embodiments of an actuator 101 can include two
bellows 300E, 300W, further embodiments can comprise a single
bellows 300 or any suitable plurality of bellows 300. In various
embodiments, actuators 101 include orifices which equalize the flow
among many actuators 101, and/or limit the rate of motion as
discussed herein.
[0035] Turning to FIG. 4, in various embodiments, a plurality of
solar trackers 100 can be actuated by a row controller 380 in a
solar tracking system 400. In this example, four solar trackers
100A, 100B, 100C, 100D can be controlled by a single row controller
380, which is shown being operably coupled thereto. As described in
more detail herein, in some examples, a plurality of trackers 100
or a subset of trackers 100 can be controlled in unison. However,
in further embodiments, one or more trackers 100 of a plurality of
trackers 100 can be controlled differently than one or more other
trackers 100.
[0036] While various examples shown and described herein illustrate
a solar tracking system 400 having various pluralities of rows of
trackers 100, these should not be construed to be limiting on the
wide variety of configurations of photovoltaic panels 103 and
pneumatic actuators 101 that are within the scope and spirit of the
present disclosure. For example, some embodiments can include a
single row or any suitable plurality of rows, including one, two,
three, four, five, six, seven, eight, nine, ten, eleven, twelve,
fifteen, twenty, twenty five, fifty, one hundred, and the like.
[0037] Additionally, a given row can include any suitable number of
actuators 101 and photovoltaic panels 103, including one, two,
three, four, five, six, seven, eight, nine, ten, eleven, twelve,
fifteen, twenty, twenty five, fifty, one hundred, two hundred, five
hundred, and the like. Rows can be defined by a plurality of
physically discrete tracker units. For example, a tracker unit 100
can comprise one or more actuators 101 coupled to one or more
photovoltaic panels 103.
[0038] In some preferred embodiments, the axis of a plurality of
solar trackers 100 can extend in parallel in a north-south
orientation, with the actuators 101 of the rows configured to
rotate the photovoltaic panels about an east-west axis. However, in
further embodiments, the axis of trackers 100 can be disposed in
any suitable arrangement and in any suitable orientation. For
example, in further embodiments, some or all rows may not be
parallel or extend north-south. Additionally, in further
embodiments, rows can be non-linear, including being disposed in an
arc, circle, or the like. Accordingly, the specific examples herein
(e.g., indicating "east" and "west") should not be construed to be
limiting.
[0039] Also the rows of trackers 100 can be coupled to the ground,
over water, or the like, in various suitable ways including via a
plurality of posts. Additionally, while various embodiments
described herein describe a solar tracking system 400 configured to
track a position of the sun or move to a position that provides
maximum light exposure, further examples can be configured to
reflect light to a desired location (e.g., a solar collector), and
the like.
[0040] FIG. 5 is an exemplary illustration of a set of rows,
including a first tracker 100A and second tracker 100B, with each
tracker 100 comprising a plurality of actuators 101 disposed along
a common axis (e.g., as shown in FIGS. 1a, 1b and 4) with each
actuator 101 comprising a first and second bellows 300. More
specifically, FIG. 5 illustrates a first solar tracker 100A that
comprises a first actuator 101AA and a second actuator 101AB on
which a first set of photovoltaic cells 103A are disposed. The
first actuator 101AA of the first tracker 100A comprises east and
west bellows 300AE.sub.1, 300AW.sub.1 and the second actuator 100B
of the first tracker 100AB comprises east and west bellows
300AE.sub.2, 300AW.sub.2.
[0041] A second solar tracker 100B comprises a first actuator 101BA
and a second actuator 101BB on which a second set of photovoltaic
cells 103B are disposed. The first actuator 101BA of the second
tracker 100B comprises east and west bellows 300BE.sub.1,
300BW.sub.1 and the second actuator 100BB of the second tracker
100B comprises east and west bellows 300BE.sub.2, 300BW.sub.2.
[0042] A row controller 380 is shown comprising a pneumatic control
unit 384 that is operably connected to a pneumatic circuit 382 that
drives the bellows 300 of the first and second trackers 101A, 101B
via respective pneumatic lines 390 that are configured to introduce
and/or remove fluid from the bellows 300 (e.g., via respective
bellows branches 392 that extend from the pneumatic lines 390).
More specifically, a first east pneumatic line 390E.sub.1 is shown
being operably connected to the first and second east bellows
300AE.sub.1, 300AE.sub.2 of the first tracker 100A. Accordingly,
because the first and second east bellows 300AE.sub.1, 300AE.sub.2
of the first tracker 100A share a common pneumatic line 390E.sub.1,
pneumatic circuit 382 can drive, introduce fluid to, remove fluid
from, and/or otherwise control the first and second east bellows
300AE.sub.1, 300AE.sub.2 in unison via the common pneumatic line
390E.sub.1.
[0043] Similarly, a first west pneumatic line 390W.sub.1 is shown
being operably connected to the first and second west bellows
300AW.sub.1, 300AW.sub.2 of the first tracker 100A. Accordingly,
because the first and second west bellows 300AW.sub.1, 300AW.sub.2
of the first tracker 100A share a common pneumatic line 390W.sub.1,
pneumatic circuit 382 can drive, introduce fluid to, remove fluid
from, and/or otherwise control the first and second west bellows
300AW.sub.1, 300AW.sub.2 in unison via the common pneumatic line
390W.sub.1.
[0044] Accordingly, with the first and second east bellows
300AE.sub.1, 300AE.sub.2 and the first and second west bellows
300AW.sub.1, 300AW.sub.2 being respectively configured to be driven
in unison, the first and second actuators 101AA, 101AB of the first
solar tracker 100A can be driven in unison, which allows for the
set of photovoltaic cells 103A coupled to the first and second
actuators 101AA, 101AB to be rotated laterally about a common axis
that extends through the first and second actuators 101AA,
101AB.
[0045] While this example of FIG. 5 illustrates the first tracker
100A comprising a first and second actuator 101AA, 101AB, it should
be clear that a plurality of actuators 101 can be driven or
controlled in a similar manner, including trackers 100 having four
actuators 101 as illustrated in FIGS. 1a, 1b and 4.
[0046] The second tracker 100B is shown having a similar
configuration. More specifically, a second east pneumatic line
390E.sub.2 is shown being operably connected to the first and
second east bellows 300BE.sub.1, 300BE.sub.2 of the second tracker
100B. Accordingly, because the first and second east bellows
300BE.sub.1, 300BE.sub.2 of the second tracker 100B share a common
pneumatic line 390E.sub.2, pneumatic circuit 382 can drive,
introduce fluid to, remove fluid from, and/or otherwise control the
first and second east bellows 300BE.sub.1, 300BE.sub.2 in unison
via the common pneumatic line 390E.sub.2.
[0047] Similarly, a second west pneumatic line 390W.sub.2 is shown
being operably connected to the first and second west bellows
300BW.sub.1, 300BW.sub.2 of the second tracker 100B. Accordingly,
because the first and second west bellows 300BW.sub.1, 300BW.sub.2
of the second tracker 100B share a common pneumatic line
390W.sub.2, pneumatic circuit 382 can drive, introduce fluid to,
remove fluid from, and/or otherwise control the first and second
west bellows 300BW.sub.1, 300BW.sub.2 in unison via the common
pneumatic line 390W.sub.2.
[0048] As discussed herein, pneumatics can introduce and/or remove
fluid from bellows 300 of one or more actuators 101. For example,
pneumatics can actuate a plurality of actuators 101 associated with
a solar tracker 100. In further examples, pneumatics can actuate a
plurality of solar trackers 100 disposed in one or more rows. In
various embodiments, a pneumatics system (e.g., including the
pneumatic circuit 382, pneumatic lines 290, and the like) can
comprise a plenum structure for a CADS harness, which in some
embodiments can include a high flow capacity main line with flow
restrictions 391 on bellows branches 392 to maintain main line
pressure on long rows. In some embodiments, pneumatic routing can
be disposed on the north side of all actuators of a tracking system
400. In further embodiments, pneumatic routing can be disposed
exclusively on the south side of all actuators of the tracking
system 400 or on both the north and south sides.
[0049] In some embodiments, (e.g., as shown in FIG. 5) flow
restrictions 391 on some or all bellows branches 392 can be
desirable for equalizing flow (and therefore motion rate) of some
or all actuators 101 in a tracker 100, a row of trackers 100 or
across rows of differing lengths and differing pneumatic impedance.
The flow restrictions 391 can be tuned to equalize flow within a
desired percentage range in accordance with various embodiments.
Such configurations can equalize motion rate for some or all of the
actuators (keeps panels matched) and can allow for more arbitrary
field layout of pneumatic lines 390. Various embodiments can
include a hermetic connector-to-bellow polymer-weld. Further
embodiments can comprise air brake tubing and fittings for a solar
application. In some embodiments, the pneumatic circuit 382, using
low pressure, can pump between CADS channels rather than using a
source/exhaust system. For example, the system can comprise a row
controller 380 that pumps between CADS channels.
[0050] Some embodiments can comprise a
replenish-leaks-on-power-loss function. For example, an additional
low pressure regulator can be added to a row controller 380 or
other portion of the solar tracking system 400, with a
normally-open valve connecting it to a manifold cross-over. The
valve can be held closed when the system is powered. When power is
lost, the valve opens, replenishing any leaks from an attached
high-pressure air tank. This can allow the solar tracking system
400 to maintain a stow position for an extended period of
power-loss, even with leaks in the system. For example, FIGS. 8 and
15 of U.S. patent application Ser. No. 15/955,506 referenced above
and incorporated by reference herein illustrate example embodiments
of row controllers featuring a "replenish-leaks-on-power-loss"
function.
[0051] In further embodiments the solar tracking system 400 can
comprise a wind flutter damper-compressor. For example, some
configurations can use the fluttering motion of a tracker 100
induced by wind to operate a compressor to augment air supply. One
or more pistons (or bellows 300) distributed throughout the tracker
100 can generate additional makeup air to reduce energy consumption
while also limiting the magnitude of any fluttering behavior
preventing resonance. Additionally, some embodiments can comprise a
double 5/2 valve arrangement, which can include a source or exhaust
connected to east-output or west-output.
[0052] Turning to FIG. 6, a block diagram of a set of elements 600
of one example embodiment of a solar tracking system 400 is
illustrated, which includes a row controller 380 and a first and
second solar tracker 100A, 100B. The row controller 380 is shown
comprising a control device 651, a fluid source 652, a fluid source
pressure sensor 653, a temperature sensor 654, a wind sensor 655, a
sun sensor 656 and a clock 657. FIG. 14 is a block diagram that
illustrates another example embodiment of a solar tracking system
400 that comprises an array controller 1400 a first and second row
controller 380 and a first, second, third, fourth solar tracker
100A, 100B, 100C, 100D.
[0053] The embodiments of FIGS. 6 and 14 are merely examples and
should not be construed to be limiting on the wide variety of
architectures of a solar tracking system 400 that are within the
scope and spirit of the present disclosure. For example, some
embodiments can include an array controller 1400 that controls one
or more row controller 380, which in turn control one or more solar
trackers 100. In some embodiments, one or both of the array
controller 1400 and/or row controllers 380 can be absent, with one
or more remaining elements performing sensing and/or control
functions.
[0054] Additionally, while the array controller 1400, row
controller 380 and solar tracker 100 are shown having a plurality
of control and sensing elements, in some examples any shown
elements can be absent or additional control and/or sensing
elements can be present. In other words, in further examples, any
of the array controllers 1400, row controller 380 and solar tracker
100 can be more or less complex and can have more or fewer elements
compared to the examples of FIGS. 6 and 14.
[0055] For example, in some embodiments east/west bellows pressure
sensors 601E, 601W can be disposed at one or more row controller
380 and/or array controller 1400 and not the solar trackers 100. In
further embodiments, east/west bellows pressure sensors 601E, 601W
can be disposed at one or more solar tracker 100, which in some
embodiments can include east/west bellows pressure sensors 601E,
601W associated with one or more actuators 101 of such trackers
100. Still further embodiments can include east/west bellows
pressure sensors 601E, 601W on every row of trackers 100, on every
couple of rows of trackers 100, and the like.
[0056] Accordingly, in some examples, bellows sensors 601 can be
co-located at one or more bellows 300 or can be associated with
pneumatic lines associated with one or more bellows 300. For
example, in some embodiments, bellows pressure sensors 601 can be
respectively configured to sense the pressure of a single bellows
300 or the pressure of a group of bellows 300 including a plurality
of east bellows 300E, a plurality of west bellows 300W, one or more
bellows 300 from a plurality of trackers 100, and the like.
[0057] Also, any of the functions or methods described herein can
be performed exclusively at one of an array controller 1400, row
controller 380 and solar tracker 100 in some embodiments, or can be
performed collectively by two or more of an array controller 1400,
row controller 380 and solar tracker 100. For example, it should be
appreciated that embodiments illustrating functions or method being
performed by a row controller should be construed to be performed
alternatively and/or additionally by one or both of an array
controller 1400 and row controller.
[0058] In various embodiments, the control device 651 can be any
suitable computing device, which can include a processor, memory,
power source, networking hardware, and the like. The control device
651 can store computer readable instructions (e.g., software,
firmware and the like) on one or more computer readable medium,
which can control one or more pneumatic circuits 382, which can in
turn drive or control one or more solar trackers 100 as described
in more detail herein. In various embodiments, a pneumatic control
unit 384 can comprise the control device 651 or vice versa. In some
embodiments, the control device 651 can comprise a specialized
embedded system or can comprise devices such as a smartphone,
laptop computer, tablet computer or the like.
[0059] Some embodiments can comprise solar electrical string
powered controls with no battery backup. For example, the array can
be used to power controls. In one configuration, a large array 400
can have significant available energy even early in the morning
before inverters start. A 50 kW array (e.g., including eight
trackers 100) with 10 W/m{circumflex over ( )}2 irradiance can
generate 500 W which can be sufficient to power control systems.
Even cloudy days can have more than enough power to run a
compressor. Such embodiments can be employed with or without
battery backup. Additionally, the control system can be configured
to move one or more trackers 100 of an array 400 away from
vulnerable positions before energy is lost for the day. In such
examples, a stow-on-power-loss function can be desirable.
[0060] While backup power can be provided via a battery, further
embodiments can comprise a wind turbine to provide backup power (or
backup air supply) during wind events combined with power outages.
Risks to a solar array structure can be greatest during extreme
wind events, and using wind to provide energy can help guarantee
that energy is available when needed.
[0061] While some embodiments include the control device 651 being
located onsite and proximate to one or more solar trackers 100
being controlled, further embodiments can include the control
device 651 or portions thereof being located in a disparate
location from the solar trackers 100. For example, in some
embodiments, control device 651 or portions thereof can be embodied
in one or more physical or virtual computing devices located away
from the solar trackers 100 and control data and sensing data can
be communicated to and from such a disparate location via various
suitable networks, including a cellular network, satellite network,
the Internet, a Wi-Fi network, microware network, a laser network,
a serial communications system, or the like.
[0062] The fluid source 652 can comprise any suitable container for
storing fluid. For example, in embodiments where air is used as a
fluid for controlling bellows 300 of one or more solar trackers
100, the fluid source 652 can comprise one or more air tank and/or
air compressor of any suitable size and shape. While some
embodiments include a fluid source 652 at the row controller 380,
further embodiments can include one or more fluid sources 652
proximate to one or more solar trackers 100. For example, where a
plurality of solar trackers 100 are disposed in a row, a fluid
source can be disposed at an end of a row. Additionally, where
other fluids (e.g., oxygen, nitrogen, water, oil, or the like) are
used, a fluid source 652 can be configured to store such
fluids.
[0063] A fluid source pressure sensor 653 can be associated with a
fluid source 652 and can be configured to sense a pressure
associated with the fluid source 652. Additionally in further
embodiments, the pressure sensor 653 or other sensors can be
configured to sense a volume of fluid present within the fluid
source 652. Data associated with a pressure, volume or the like, of
a fluid source can be used as discussed in more detail herein.
[0064] The row controller 380 and/or array controller 1400 can
comprise various additional sensors, including a temperature sensor
654, a wind sensor 655, a sun sensor 656, and the like. As
discussed herein, a temperature sensor 654 can be configured to
sense a temperature associated with, and can be configured to
determine a fluid volume, or the like, within various portions of a
solar tracking system 400, including the fluid source 652,
pneumatic lines 370, pneumatic circuit 382, or the like. A wind
sensor 655 can be used to determine wind speed or velocity near the
row controller 380, which as discussed herein can be used to
determine whether one or more solar trackers 100 should be moved to
a stowed position to prevent wind damage to the solar trackers 100,
whether rigidity of one or more actuators 101 should be increased
or decreased, or whether an alert should be sent to a user
regarding wind conditions.
[0065] As discussed herein, a solar tracking system 400 can be
configured to move one or more solar trackers 100 to track the
position or angle of the sun, which can be desirable for maximizing
electrical energy generated by photovoltaic cells 103 of the system
400. In some embodiments, the sun sensor 656 can be used to
determine an angle or position of the sun, which can be used to
determine how the solar trackers 100 should be driven as discussed
herein. However, in further embodiments, a sun sensor 656 can be
absent and an angle or position of the sun can be determined in
other ways.
[0066] In various embodiments, a clock 657 can be used to determine
an angle or position of the sun. For example, where the location of
the solar tracking system 400 and/or components thereof are known
(e.g., via GPS or a defined location indicator), astrological
charts can be consulted which can identify a position or angle of
the sun at the location at a time defined by the clock 657.
Accordingly, in various embodiments, the row controller 380 can
store or otherwise have access to astrological charts that identify
what the angle and/or position of the sun will be at various times
in the future relative to one or more locations.
[0067] A row controller 380 is shown being operably connected to
first and second solar trackers 100A, 100B in FIG. 6. An array
controller 1400 is shown as being operably connected to a first and
second row controller 380 in FIG. 14. Such an operable connection
can include a fluidic and/or data communication connection with the
solar trackers 100 and/or row controller 380 in the case of array
controller 1400. For example, a fluidic connection can include
fluidic lines 390 (see FIGS. 3 and 5) that allow fluid to travel
from the array controller 1400 and/or row controller 380 to the one
or more solar trackers 100 and/or vice versa. However, in some
embodiments, where a fluid source 652 is absent at the row
controller 380 and/or array controller 1400, such a fluidic
connection can be absent. For example, where one or more fluid
sources 652 are located at one or more trackers 100, an operable
connection between the row controller 380 and the one or more
trackers 100 can include only a data communication connection. In
another example, one or more trackers 100 can be self-powered with
distributed air compressors or pumps.
[0068] In various embodiments, a data communication connection can
include any suitable wired and/or wireless communication channel
that allows data to pass from the array controller 1400 to one or
more row controller 380, from one or more row controllers 380 to
the one or more solar trackers 100 and/or vice versa. For example,
in some embodiments, sensing data from the one or more solar
trackers 100 can be communicated to the one or more row controllers
380 and/or array controller 1400 as discussed herein, which can
inform control of the one or more solar trackers 100 by a row
controller 380 and/or array controller 1400. Additionally or
alternatively, control data, or other suitable data (e.g., sensing
data) can be communicated to the one or more solar trackers 100
from the row controller 380 and/or array controller 1400. For
example, where valves or other components are present at the one or
more trackers 100, such valves or components can be controlled via
data sent to the one or more trackers 100 from a row controller 380
and/or an array controller 1400 that controls a plurality of row
controllers 380.
[0069] The solar trackers 100A, 100B can include a respective one
or more east bellows 300AE, 300BE that are associated with one or
more respective east bellows pressure sensors 601AE, 601BE. Solar
trackers 100A, 100B can further include a respective one or more
west bellows 300AW, 300BW that are associated with one or more
respective west bellows pressure sensors 601AW, 601BW. For example,
as discussed and shown herein (e.g., in FIGS. 1a, 1b, 4 and 5), a
solar tracker 100 can comprise one or more actuators 101 that each
comprise a pair of bellows 300.
[0070] In various embodiments, a bellows pressure can be used to
determine an inflation/deflation state of the bellows 300, a volume
of fluid present in the bellows, and the like, which can be
desirable for monitoring and controlling the bellows 300 of a solar
tracking system 400. Some embodiments can include one or more
pressure sensor 601 associated with a given bellows 300, whereas
further embodiments can include pressure sensors associated with
only a subset of bellows 300. Pressure sensors can be disposed
proximate to, within or on a bellows 300 or can be operably coupled
to a fluidic line 390 or branch 392 associated with one or more
bellows 300. Bellows pressure data obtained from one or more
pressure sensors 601 can be used as discussed in more detail
herein.
[0071] Additionally, the solar trackers 100A, 100B can comprise
various additional sensors, including respective inclinometers
603A, 603B, temperature sensors 605A, 605B, wind sensors 607A,
607B, and the like. In various embodiments, an inclinometer 603 can
measure an angle of slope or tilt of the photovoltaic cells 103
associated with a tracker 100. For example, an inclinometer 603 can
measure an angle of slope or tilt associated with a tracker 100
being in a neutral configuration N, maximum tilts A, B, or any
other configurations therebetween, as shown in FIG. 2. Such an
identified angle of slope or tilt associated with photovoltaic
cells 103 can be used to determine the position of the photovoltaic
cells 103 of the tracker 100 relative to a position or angle of the
sun as discussed in more detail herein.
[0072] In some embodiments, a tracker 100 can comprise one or more
inclinometers 603 that can be coupled with or associated with
various portions of a tracker 100, including a top plate 330,
actuator 101, photovoltaic cells 103, or the like. Additionally, in
further embodiments, inclinometers 603 can be absent and/or other
suitable sensors can be used to determine an angle of slope or tilt
associated with photovoltaic cells 103.
[0073] As discussed herein, temperature sensors 605A, 605B can be
configured to determine a temperature associated with, and
configured to determine a fluid volume, or the like, within various
portions of a solar tracking system 400, including the bellows 300,
pneumatic lines 370 or the like. The wind sensors 607A, 607B can be
used to determine wind speed or velocity near solar trackers 100A,
100B, which as discussed herein can be used to determine whether
one or more solar trackers 100 should be moved to a stowed position
to prevent wind damage to the solar trackers 100, whether rigidity
of one or more actuators 101 should be increased or decreased, or
whether an alert should be sent to a user regarding wind
conditions.
[0074] In further embodiments, control of a solar tracking system
400 can comprise temperature and humidity abatement via pneumatic
venting, which can include opening both fill and vent valves in a
row controller 380 or other suitable location and/or using an
orificed connection for a row controller 380. Further control
system embodiments can comprise modifying/controlling Voc (open
circuit voltage), which can be desirable for reducing design
constraints (e.g., string length) and improve cost of inverters,
combiner boxes, wiring, and the like. Some embodiments can include
modifying/controlling Isc (short circuit current), which can reduce
design constraints (e.g., current) and can improve the cost of
inverters, combiner boxes, wiring, and the like. Still further
embodiments can comprise modulating the tracker position to
increase convection and therefore increase operating voltage and
energy output.
[0075] In some instances, it can be desirable to reduce the range
of motion of one or more tracker 100, including by limiting the
range of motion of one or more actuator 101, bellows 300, or other
suitable portion of a tracker 100. For example, limiting the range
of motion of one or more tracker 100 can be performed in response
to environmental or system conditions, including elevated wind
events, high temperature events, low temperature events, and the
like. Limiting the range of motion of the tracker 100 can include
limiting the range of motion of a tracker 100 to a smaller range of
motion compared to a standard range of motion of the tracker 100,
with some examples including immobilizing the tracker 100. In some
examples, generating a stow of a tracker 100 can include limiting
the range of motion of the tracker 100 in response to a stow
event.
[0076] Some embodiments can comprise off-angle tracking for
electrical current health inspection. For example, off-angle
tracking during high irradiance hours can provide an indication of
string level health or health of a row controller's worth of
panels. In some embodiments, such a determination can comprise
measuring a dip in current output when portions of an array's
tracker are pointed away from the sun. Where actuators 101 or other
portions of a tracker 100 are broken, wiring is wrong, or the like,
less of a dip would be observed, which could indicate an issue with
the system in that portion. On the other hand, where actuators 101
or other portions of a tracker 100 are healthy, larger dips during
off-sun tracking would be observed, which could indicate that
portion of the system being healthy. Further embodiments can
comprise a pressure/position check to monitor bellows for material
degradation or other defects.
[0077] Some embodiments can use pulse width modulation (PWM) or
proportional voltage or current control to control valves instead
of calculated open-time in order to optimally utilize valve cycle
life and minimize tracker twist due to long valve open times.
Further embodiments can be configured to monitor pressures/angles
of one or more actuators 101 to determine a leak location. For
example, leaks can be predicted if pressures/angles in a particular
row or tracker 101 are changing differently than other
rows/trackers, or differently than expected based on temperature
variations and other factors. This can allow leaks to be located on
the row-level or tracker-level. Leaks can be located even more
precisely, in still further embodiments, with more sensors and/or
by learning the system response to leaks as a function of leak
location, and adapting control code to recognize patterns that are
characteristic of specific leak locations.
[0078] While FIG. 6 and the examples discussed herein illustrate
specific example embodiments of a solar tracking system 400, these
examples should not be construed to be limiting on the wide variety
of suitable configurations of a solar tracking system 400. For
example, any of the elements can be absent in some embodiments, or
can be present in a plurality in some embodiments. Additionally,
various sensors or elements shown located at the row controller 380
can alternatively, or additionally, be located at the solar
trackers 100, or vice versa. Also, it should be clear that the
example sensors or elements shown in FIG. 4 can be replaced or
augmented by suitable equivalents or other sensors or elements that
provide for similar functionalities.
[0079] FIG. 7 illustrates an example of a tracker 100 tracking the
position of sun 700 throughout the day as the sun 700 moves through
the sky. As shown in this example, one or more photovoltaic cells
103 disposed on the tracker 100 are oriented facing the sun 700
such that tracker axis 750, which is perpendicular to the planar
face of the photovoltaic cells 103, is coincident with the sun 700.
Accordingly, as shown in this example, the tracker 100 can pivot
the photovoltaic cells 103 throughout the day (e.g., via actuators
101) to match the angle or location of the sun 700 such that the
photovoltaic cells 103 receive maximum sun exposure, which can
maximize generation of electrical current by the photovoltaic cells
103.
[0080] However, in further embodiments, a tracker 100 can track the
changing position or angle of the sun 700 in various suitable ways.
For example, while the example of FIG. 7 illustrates tracking such
that tracker axis 750 is coincident with the center of the sun 700,
in further embodiments, it can be desirable to track the sun 700
with tracker axis 750 not being coincident with the center of the
sun 700.
[0081] For example, in some embodiments, photovoltaic cells 103 can
be configured with an optimal exposure angle that is not directly
perpendicular to the planar face of the photovoltaic cells 103. In
further examples, heat generated at the photovoltaic cells 103 via
exposure with tracker axis 750 being coincident with the center of
the sun 700 can reduce electrical output, so pointing the tracker
700 off-center of the sun can be desirable in some embodiments.
Additionally, variables like angle or position of the sun in the
sky, weather conditions, or the like can also affect an optimal
exposure angle of the photovoltaic cells 103. Accordingly, the
examples herein should not be construed as limiting.
[0082] Turning to FIGS. 8a and 8b, an example of a tracker 100
being in a non-ideal position relative to the sun 700 is shown in
FIG. 8a and moving the tracker 100 to an ideal position with
tracker axis 750 being coincident with the center of the sun 700 is
shown in FIG. 8b. As discussed herein, it can be desirable for
solar trackers 100 to track the position or angle of the sun 700 to
maximize electrical current output by photovoltaic cells 103 on the
tracker 100. For example, where it is determined that the current
angle of the photovoltaic cells 103 of the tracker 100 is not
within a desirable range of an optimal exposure angle of the
photovoltaic cells 103, then the tracker 100 can be tilted so that
the photovoltaic cells 103 are positioned within a desirable range
of an optimal exposure angle of the photovoltaic cells 103. Using
the examples of FIGS. 8a and 8b, in FIG. 8a, it can be determined
that the tracker 100 is in a non-ideal configuration and can be
moved to, or within a range of an ideal configuration, for example,
by rotating the photovoltaic cells 103 to the right as shown in
FIG. 8b.
[0083] FIG. 9 illustrates an example method 900 of controlling one
or more solar trackers 100 to match the angle or position of the
sun. For example, in various embodiments a pneumatic control unit
384 (FIGS. 3 and 5) or control device 651 (FIG. 6) can be
configured to perform the method 900 of FIG. 9, or the like.
[0084] The method 900 begins at 910, where a current angle or
position of the sun is determined. For example, in some embodiments
a current angle of the sun can be determined based on a determined
time (e.g., via a clock 657 in FIG. 6), a determined or defined
position of a tracker 100 or solar tracking system 400, and based
on astrological sun charts that indicate sun position based on time
and location. In further embodiments, a current angle or position
of the sun can be determined based on a sun sensor 656 (FIG. 6) or
other suitable method or device.
[0085] The method 900 continues at 920 where an ideal angle of the
photovoltaic panels 103 to match the current angle of the sun is
determined. For example, as discussed herein, such an ideal angle
of the photovoltaic panels 103 can be an angle where the tracker
axis 750 is coincident with the center of the sun 700 (see e.g.,
FIGS. 7 and 8b) or other suitable angle, which can include an angle
that maximizes the electrical output of the photovoltaic cells
103.
[0086] At 930, a current angle of the photovoltaic cells 103 is
determined, and at 940 a difference between the current angle of
the photovoltaic cells 103 and the ideal angle of the photovoltaic
cells 103 is determined. For example, as discussed herein, in some
embodiments, one or more inclinometer 603A, 603B of a respective
solar tracker 100 can be used to identify a current angle of the
photovoltaic cells 103.
[0087] The method 900 continues at 950 where a determination is
made whether the difference between the current angle of the
photovoltaic cells 103 and the ideal angle of the photovoltaic
cells 103 is within a defined range. For example, in various
embodiments, a tolerance range about an ideal angle of the
photovoltaic cells 103 can be desirable to allow for movements of
the photovoltaic cells 103 in the wind; to conserve energy by not
requiring constant movement of the photovoltaic cells 103 to
maintain an exact ideal angle, and the like. For example, such a
tolerance range can be +/-0.5.degree., +/-1.0.degree.,
+/-2.0.degree., +/-3.0.degree., +/-5.0.degree., +/-10.0.degree.
+/-15.0.degree. and the like. Additionally, such a tolerance range
can be symmetrical about an ideal angle as shown in the examples
above or can be asymmetrical. Additionally, such a tolerance range
can be static or dynamic based on various factors, including the
current angle of the sun, weather conditions, or the like.
[0088] If a determination is made at 950 that the difference
between the current angle of the photovoltaic cells 103 and the
ideal angle of the photovoltaic cells 103 is not within a defined
range, then the method 900 continues to 960 where bellows 300 of
one or more actuators 101 of one or more trackers 100 are inflated
and/or deflated to change the angle of the photovoltaic panels 103
toward the determined ideal angle for the photovoltaic panels 103.
However, if at 950 a determination is made that the difference
between the current angle of the photovoltaic cells 103 and the
ideal angle of the photovoltaic cells 103 is within the defined
range, then the method 900 cycles back to 910.
[0089] Accordingly, in various embodiments, the position of one or
more trackers 100 can be monitored to determine whether the angle
of the trackers 100 is within a tolerance range of an ideal angle,
and if not, the trackers 100 can be actuated to be within the
tolerance range. In various embodiments, such monitoring and
control can be applied to all trackers 100 within a solar tracking
system 400 or one or more subsets of trackers 100 can be monitored
and controlled separately. For example, in some embodiments, it can
be desirable to control trackers 100 individually based on
individual current angles of the trackers 100 and/or individual
locations of the trackers 100. Also, such monitoring and control
can be performed continuously or can be performed periodically. For
example, the method 900 can be performed on a time delay every
second, five seconds, ten seconds, sixty seconds, five minutes,
fifteen minutes, thirty minutes, or the like.
[0090] In various embodiments, solar trackers 100 can enable
tweaking of photovoltaic system performance characteristics to
capture additional value. For example, open circuit voltage of
photovoltaic cells 103 can increase as temperature decreases.
Overall system design of some embodiments can be dictated by a
maximum voltage that occurs very infrequently (e.g., on the coldest
mornings of the coldest days of the year). Intelligent tracking can
ameliorate this worst case scenario and can improve project design
economics.
[0091] To avoid this scenario, controls of some embodiments can
leverage another principle of photovoltaic cells 103; namely that
cell voltage can also be related to incident light. By pointing the
trackers 100 somewhere other than directly at the sun, resulting in
fewer photons striking the photovoltaic cells 103, system voltage
is reduced. When photovoltaic cell 103 temperature rises from a
combination of ambient temperature and direct solar heating of the
photovoltaic cells 103, system voltage can be reduced further, and
the trackers 100 can then return to a position with maximum
incident light on the photovoltaic cells 103.
[0092] This application can include a combination of design
features such as detecting photovoltaic cells string voltage (e.g.,
directly or through query of some other system device such as an
inverter), sensing of ambient temperature or photovoltaic cells'
temperature, measurement of direct or indirect solar irradiance,
and the like.
[0093] One benefit of being able to relax the constraint of minimum
design temperature in some embodiments can be the potential for
more photovoltaic cells 103 (and system power) per infrastructure
investment. For example, wiring can be done per string, combiner
boxes accept a maximum number of strings, and the like. If the
number of photovoltaic cells 103 per string increases by 5%, the
same amount of power can be generated with 5% fewer strings, and
the infrastructure investment associated with those eliminated
strings can be avoided. There is also potential for reduction in
installation labor, as wiring of additional strings is much more
involved than additional photovoltaic cells 103.
[0094] Additionally, higher system voltage can drive additional
system efficiency by reducing the string current at a fixed power
output. This can be directly valued in additional energy
production, or can enable other system savings through reduction of
conductors or the like. Further embodiments can comprise moving
photovoltaic cells 103 using intelligent algorithms to improve
performance or system design.
[0095] Turning to FIGS. 10 and 11, a state diagram 1000 is shown in
FIG. 10 with reference to a tracking window 1100 illustrated in
FIG. 11. As shown in FIG. 11, the tracking window 1100 can comprise
a negative east tracking window portion 1101 and a positive west
tracking window portion 1102 that have equal size on opposing sides
of a current angle of the sun 1103. A negative east tracking window
half 1105 separates an east invalid region (EIR) and an east
semi-valid region (ESVR). A positive west tracking window half 1105
separates a west semi-valid region (WSVR) and a west invalid region
(WIR). An east out of bound region (EOB) and west out of bounds
region (WOB) are on distal ends of the tracking window 1100. An
east valid region (EVR) and west valid region (WVR) are separated
by the current angle of the sun 1103.
[0096] As discussed herein, control determinations can be made for
one or more trackers 100 based at least in part on a determination
of where a current angle of the tracker 100 is within the tracking
window 1100 compared to the current angle of the sun or an ideal
tracker target angle. Turning to FIG. 10, where a tracker 100 is in
a locked position 1001, if at 1004 the tracker 100 is determined to
be in the east semi-valid region (ESVR) or in the east invalid
region (EIR) and the current destination angle is moving west
CAD-MW, then the tracker 100 is actuated to move west 1006.
Additionally, where the tracker 100 is in a locked position 1001
and the tracker 100 is determined at 1004 to be in the east out of
bounds region (EOB), then the tracker 100 can be actuated to move
west 1006.
[0097] For example, a locked position for the tracker 100 can
include various configurations, including a stopped configuration
where the tracker 100 is not being actuated by fluid being
introduced and/or removed from the bellows 300 such that the
actuators 101 are in a state of equilibrium. Such a locked
configuration may or may not include a mechanical locking mechanism
in addition to an equilibrium state between bellows 300 of one or
more actuators 101. In some embodiments, a locked state can
comprise valves associated with the bellows 300 being in a closed
configuration.
[0098] Also, equilibrium between bellows 300 of an actuator 101 can
include a range of pressures. For example, where bellows pressures
of X:X generate equilibrium of an actuator 101 such that the
actuator 101 does not move, bellows pressures of 2.times.:2.times.,
5.times.:5.times., 10.times.:10.times. and the like, can also
generate equilibrium of an actuator 101. In various embodiments,
higher pressures of equilibrium can generate more stiffness in the
actuator 101, which can be desirable for resisting external forces
(e.g., wind) that may cause rotation of the photovoltaic cells 103.
However, higher pressures in the bellows 300 can require more fluid
and energy, which may undesirably consume more energy than
necessary and/or cause more wear on bellows 300 or other components
of a tracker 100. Accordingly, in some embodiments, it can be
desirable to keep relative pressure between bellows 300 as low as
possible to maintain appropriate function of the tracker 100.
[0099] Returning to the state diagram 1000 of FIG. 10, if the
tracker 100 is moving west 1006 and it is determined at 1008 that
the bellows 300 with most pressure (BMP) has a pressure that is
less than a max pressure high (MPH) and where bellows 300 with most
pressure (BMP) also has a greater pressure than a max pressure low
(MPL), then at 1010, the west bellows 300W of the tracker 100 will
vent and the east bellows 300E will fill.
[0100] For example, as discussed above, high fluid pressure in
bellows 300 can cause undesirable wear on the bellows 300 and can
even cause failure of the bellows 300 or related components.
Accordingly, a max pressure high (MPH) can be defined for the
bellows 300, which can be based on a maximum bellows operating
pressure that limits undesirable wear on the bellows 300 and is
below a pressure that would cause failure of the bellows 300.
[0101] Similarly, while low bellows operating pressures can be
desirable for consuming less energy and limiting wear on the
bellows 300 and other components, low bellows operating pressures
below a certain threshold can be inadequate for desirable operation
of the actuators 101 of a tracker 100. Accordingly, a max pressure
low (MPL) can be defined for a lowest desirable operating pressure
of bellows 300 of a tracker 100.
[0102] Some embodiments can comprise variable max pressure high
(MPH) and/or a max pressure low (MPL). In one example, material
creep reduction can include adjusting a control method to have a
max bellow pressure dependent on external loads (e.g., reduce
pressure when wind speed is low and increase pressure as wind speed
increases). The reduced average pressure over time can limit
material creep. In another example, a constant bellows stress
function can include increasing pressure at a flat configuration
(e.g., parallel to the ground) to provide more stiffness in stow,
which can also provide better accuracy and decrease material
fatigue. Bellows stress can be inversely proportional to angle, and
proportional to pressure. High pressure at low angle in some
embodiments can allow for roughly constant bellows material stress
throughout the range of motion of the actuator 101. Additionally,
changing peak pressures can be desirable for controlling the
resonant modes and stiffness of a tracker and portions thereof. For
example, changing peak pressures can be desirable for withstanding
force generated by winds as discussed herein.
[0103] Returning to the state diagram 1000 of FIG. 10, where the
tracker 100 is moving west 1006 and it is alternatively determined
at 1008 that the tracker 100 is in the east invalid region (EIR) or
is in the east out of bounds region (EOB), then at 1010, the west
bellows 300W of the tracker 100 will vent and the east bellows 300E
will fill. Where, at 1010, the west bellows 300W of the tracker 100
are venting and the east bellows 300E are filling, if it is
determined at 1012 that the tracker 100 is in the west invalid
region (WIR) or is in the west out of bounds region (WOB), then the
tracker 100 assumes a locked position 1001.
[0104] However, where the tracker 100 is moving west 1006 and it is
alternatively determined at 1014 that the bellows with most
pressure (BMP) has a pressure that is greater than the max pressure
high (MPH), then the west bellows 300W of tracker 100 vent at 1016.
Where the west bellows 300W of the tracker 100 are venting west at
1016 and it is determined at 1018 that the tracker 100 is in the
west invalid region (WIR) or is in the west out of bounds region
(WOB), then the tracker 100 assumes a locked position 1001.
Alternatively, if it is determined at 1020 that the tracker 100 is
in the east invalid region (EIR) or is in the east out of bounds
region (EOB), then at 1010, the west bellows 300W of the tracker
100 will vent and the east bellows 300E will fill.
[0105] However, where the tracker 100 is moving west 1006 and it is
alternatively determined at 1022 that the bellows with most
pressure (BMP) has a pressure that is less than the max pressure
high (MPH), then the east bellows 300E of tracker 100 fill at 1024.
Where the east bellows 300E of the tracker 100 are filling at 1024
and it is determined at 1026 that the tracker 100 is in the west
invalid region (WIR) or is in the west out of bounds region (WOB),
then the tracker 100 assumes a locked position 1001. Alternatively,
if it is determined at 1028 that the tracker 100 is in the east
invalid region (EIR) or is in the east out of bounds region (EOB),
then at 1010, the west bellows 300W of the tracker 100 will vent
and the east bellows 300E will fill.
[0106] Similar actions can occur on the left half of the state
diagram 1000 of FIG. 10. For example, where a tracker 100 is in a
locked position 1001, if at 1054 the tracker 100 is determined to
be in the west semi-valid region (WSVR) or in the west invalid
region (WIR) and the current destination angle is moving east
(CAD-ME), then the tracker 100 is actuated to move east 1056.
Additionally, where the tracker 100 is in a locked position 1001
and the tracker 100 is determined at 1054 to be in the west out of
bounds region (WOB), then the tracker 100 can be actuated to move
east 1056.
[0107] If the tracker 100 is moving east 1056 and it is determined
at 1058 that the bellows 300 with most pressure (BMP) has a
pressure that is less than a max pressure high (MPH) and where
bellows 300 with most pressure (BMP) also has a greater pressure
than a max pressure low (MPL), then at 1060, the east bellows 300E
of the tracker 100 will vent and the west bellows 300W will
fill.
[0108] Where the tracker 100 is moving east 1056 and it is
alternatively determined at 1058 that the tracker 100 is in the
west invalid region (WIR) or is in the west out of bounds region
(WOB), then at 6010, the east bellows 300E of the tracker 100 will
vent and the west bellows 300W will fill. Where, at 1060, the east
bellows 300E of the tracker 100 are venting and the west bellows
300W are filling, if it is determined at 1062 that the tracker 100
is in the east invalid region (EIR) or is in the east out of bounds
region (EOB), then the tracker 100 assumes a locked position
1001.
[0109] However, where the tracker 100 is moving east 1056 and it is
alternatively determined at 1064 that the bellows with most
pressure (BMP) has a pressure that is greater than the max pressure
high (MPH), then the east bellows 300E of tracker 100 vent at 1066.
Where the east bellows 300E of the tracker 100 are venting at 1066
and it is determined at 1068 that the tracker 100 is in the east
invalid region (EIR) or is in the east out of bounds region (EOB),
then the tracker 100 assumes a locked position 1001. Alternatively,
if it is determined at 1070 that the tracker 100 is in the west
invalid region (WIR) or is in the west out of bounds region (WOB),
then at 1060, the east bellows 300E of the tracker 100 will vent
and the west bellows 300W will fill.
[0110] However, where the tracker 100 is moving east 1056 and it is
alternatively determined at 1072 that the bellows with most
pressure (BMP) has a pressure that is less than the max pressure
high (MPH), then the west bellows 300W of tracker 100 fill at 1074.
Where the west bellows 300W of the tracker 100 are filling at 1074
and it is determined at 1076 that the tracker 100 is in the east
invalid region (EIR) or is in the east out of bounds region (EOB),
then the tracker 100 assumes a locked position 1001. Alternatively,
if it is determined at 1078 that the tracker 100 is in the west
invalid region (WIR) or is in the west out of bounds region (WOB),
then at 1060, the east bellows 300E of the tracker 100 will vent
and the west bellows 300W will fill.
[0111] For the east filling at 1024 and 1010 and for the west
filling at 1074 and 1060, the fill routine can have various duty
cycles (e.g., 80% on and 20% off), with a total period that can be
based on the number of actuators 101 in a tracker 100. In various
embodiments, a pressure measurement can be taken at the end of each
off period, and if it is determined that a bellows 300 is over
pressure (e.g., greater than max pressure high (MPH)), then the off
period can be maintained and pressure measurements can be
maintained until no bellows 300 is over pressure.
[0112] As discussed herein, in various embodiments a tracking
window 1100 can be used to control one or more actuators 101 of a
solar tracker 100. Referring to the tracking window 1100, in
another embodiment, if the tracker 100 is in a valid region (e.g.,
east or west valid regions (EVR) (WVR)) and the tracker 100 is in a
locked position, then valves associated with the bellows 300 of the
actuators 101 of the tracker 100 can be in a closed configuration.
However, if the tracker 100 enters a semi-valid region (e.g., east
or west semi-valid regions (ESVR) (WSVR)), and the position of the
tracker 100 is locked, then the tracker position can be unlocked,
which can include opening one or more valves associated with the
bellows 300 of the actuators 101 of the tracker 100. For example,
at least one valve can open to introduce or remove fluid from one
or more bellows 300 to drive the tracker 100 toward the sun.
[0113] However, in some embodiments, where the tracker 100 is
determined to be in an out of bounds region (e.g., east or west out
of bounds (EOB)(WOB)), then two or more valves can be opened to
drive the tracker 100 towards the sun. For example, where the
tracker 100 crosses into an out-of-bounds region from an invalid
region, then a determination can be made as to what valve is
already on and one or more additional valves can be enabled based
on the identity of the first enabled valve.
[0114] Additionally, where the tracker 100 is driving towards the
sun, then the enabled valves can be disengaged or disabled when the
tracker 100 reaches an opposite tracking window boundary, which can
include the current angle of the sun boundary 1103, the boundary
between a valid and semi-valid region, or the like.
[0115] For introducing fluid to bellows 300, in various
embodiments, fluid will only be added to the bellows of maximum
pressure (BMP) if such bellows 300 has a pressure that is below the
bellows max pressure high (MPH) and the identified pressure of the
BMP is considered valid. In various embodiments, it can be
desirable to not increase the pressure of the BMP more than the
MPH, which in various embodiments can be defined as half of a
maximum PSI window.
[0116] In various embodiments, movement of actuators 101 by
removing or releasing fluid from bellows 300 can be the implemented
method of actuation unless the pressure identified for the relevant
pneumatic circuit is valid and the BMP has a pressure that is less
than the max pressure low (MPL), which can be defined as half of a
maximum PSI window. Additionally or alternatively, movement of
actuators 101 by removing or releasing fluid from bellows 300 can
be the implemented method of actuation unless the pressure
identified for the relevant pneumatic circuit is valid and the
tracker 100 is determined to be in an out-of-bounds region (e.g.,
east or west out of bounds (EOB) (WOB)).
[0117] Turning to FIG. 12, a method 1200 of identifying a stow
event and generating a stow in one or more tracker 100 is
illustrated. The method 1200 begins at 1205, where one or more
trackers 100 are tracking the position of the sun (e.g., as shown
in FIG. 7, 8a, 8b or 9) and at 1210, sensing data from one or more
row controller sensors and/or one or more solar tracker sensors. At
1215, the received sensing data is processed to determine whether a
stow event is present, and at 1220 a determination is made whether
a stow event is present.
[0118] For example, in some embodiments, data regarding wind speed
or velocity can be obtained from wind sensors 655 at a row
controller and/or wind sensors 607A, 607B of one or more solar
trackers 100A, 100B. Such wind data can be evaluated to determine
whether it indicates wind conditions that pose a threat to one or
more trackers 100. In other words, where the solar trackers 100
comprise large planar photovoltaic panels 103, wind force can have
a strong and undesirable impact on the panels 103, which can
potentially cause damage to the photovoltaic panels 103.
Accordingly, where wind data identifies wind conditions above a
certain threshold and for a certain time period, it can be
determined that a stow event is present (i.e., an event that
warrants stow of one or more trackers 100).
[0119] Additionally or alternatively, wind data can indicate that
actuator stiffness should be increased to make the actuators 101 of
one or more trackers more rigid to oppose wind force. For example,
as discussed herein, opposing bellows 300E, 300W of an actuator can
be at equilibrium or generate movement at various opposing
pressures, with equilibrium at greater pressures generating more
rigidity in the bellows 300E, 300W and therefore more rigidity in
the actuators 101. However, maintaining the lowest operating
pressures possible can be desirable to reduce wear on the bellows
300 and actuators 101 and also to reduce fluid and power
consumption. Accordingly, it can be desirable to have actuators 101
operate at a minimum operating pressure when no wind is present and
to dynamically increase pressure, stiffness or rigidity of the
actuators 101 in response to increasing wind velocity or speed.
However, at a certain threshold, it can be desirable to put the
trackers 100 into a stow configuration to protect the trackers 100
from damage.
[0120] Additionally, in various embodiments, the bellows 300 and
pressures experienced by the bellows 300 can be used to identify
whether wind is present and whether the wind conditions are such
that the tracker 100 should be put into a stow configuration for
protection against the wind or whether increasing the pressure of
the bellows 300 to prevent wobble would be desirable. For example,
where a pressure sensor associated with a bellows 300 senses a
series of pressure spikes and dips, this can be an indication of
wind affecting the position of the photovoltaic cells 103 of the
tracker 100. If such a sensed condition reaches one or more
thresholds (e.g., a maximum or minimum pressure outside of a median
pressure; number of pressure spikes and/or dips of a certain
magnitude, and the like), then the tracker 100 can be put into a
stow configuration or the pressure of the bellows 300 can be
increased to combat wobble. Although such sensing can be performed
by wind and/or pressure sensors, in further examples such sensing
can be performed by one or more of inclinometers, changes in power
output of photovoltaic cells, or any combination of pressure
sensors, inclinometers, photovoltaic power output, and the
like.
[0121] In various embodiments, it can be desirable for actuators
101 to be configured to stow on power loss. In other words, where
the pneumatics system loses power, one or more actuators 101 of the
system 400 will default to a desired safe stow position. For
example, using a cross-over valve, the valve can "normally open"
with a spring-return. It is held closed when the system is powered.
When power is lost the cross-over valve opens. This can create a
"stow on power loss" function for the system. In some examples, a
cross-over valve can connect the east and west control air tubes or
east and west valve circuits. Air from higher pressure bellows can
flow to lower pressure bellows. The cross-over valve can reduce
total system air use by up to 50%, in various embodiments.
[0122] For example, FIG. 15 illustrates an example embodiment of a
row controller 380 featuring a "stow on power loss" function.
Pressurized air can be input to a set of solenoid valves 1510
arranged into "east" and "west" valve circuits. The solenoid valves
1510 can be arranged such that they can provide the following
functions to the row controller 380: fill east, dump east, fill
west, and dump west. In some embodiments of an operating scenario,
an electronic control unit 384 can determine a need to rotate a
solar panel 103 or similar object about an axis of rotation. For
example, the electronic control unit 384 can determine a need to
rotate one or more solar panels 103 about an axis of rotation such
that the top surface of each solar panel 103 stays substantially
perpendicular to the direction of incoming solar rays as the sun
moves across the sky from east to west, requiring a rotation of the
solar panel 103 toward the west. The electronic control unit 384
can therefore command a solenoid valve 310 to open such that
pressurized air flows into the "east" control lines 390, causing
one or more "east" bellows 300 to inflate and expand, tilting the
solar panel toward the "west" direction. The electronic control
unit 384 can also determine that pressure in the "west" bellows 300
should be released to allow the "west" bellows 300 to deflate and
collapse, further allowing a rotation toward the "west."
[0123] The "east" valve circuits can be independent from control of
the "west" valve circuits. This can allows for the simultaneous
inflation or deflation of both the "east" and "west" bellows 300,
such that the overall tension in the mounting system can be
controlled. For example, in the event of a wind storm, it can be
desirable to inflate both "east" and "west" bellows 300 without
causing a change in angle of the solar panel in order to increase
the rigidity or tension in the system to handle the increased
turbulence from the storm. Similarly, it can be desirable to reduce
the overall pressure in both "east" and "west" bellows 300 at the
same time.
[0124] A fifth solenoid valve 1510V can be a "cross-over" valve
which connects the "east" and "west" valve circuits. In some
embodiments, the cross-over valve 1510V can be a "normally-open"
two-way valve, three-way valve, or the like. A "normally-open"
solenoid valve can be a valve which defaults to an open position
(such that fluid is allowed to pass through the valve) upon the
removal of power. During a normal operation of row controller 380,
cross-over valve 1510V can be energized such that it closes,
stopping fluid flow through the valve to allow independent
operation of the "east" and "west" valve circuits. However, in the
event of the removal of power, cross-over valve 1510V can default
to its "normally open" configuration, allowing the pressure in the
"east" and "west" valve circuits to equalize, which in turn allows
the solar panels to return to a "zero" position. This configuration
of row controller 380 can enable a fail-safe mode where some or all
controlled tracker rows 100 can move to a flat position if the
power being supplied to energize valve 1510V is lost. This
configuration can be called "stow on power loss."
[0125] Accordingly, a stow event can be present based upon various
detected failures in a solar tracking system 400, including power
loss, failure of pneumatic elements (e.g., bellows 300, pneumatic
lines 390, a pneumatic circuit 382, fluid source 652, valves, or
the like), failure of one or more sensors (e.g., pressure sensors
653, 601, temperature sensors 654, 605, wind sensors 655, 607, sun
sensors 656, clock 657, inclinometer 603, and the like), or failure
of control systems (e.g., the control device 651, pneumatic control
unit 384, and the like). In various embodiments, control systems
can execute a stow event or a stow event can occur automatically
upon such a failure. For example, power or pressure loss can
automatically result in fluid valves causing a stow of the trackers
100 as described herein.
[0126] Returning to the method 1200 of FIG. 12, if at 1220 it is
determined that a stow event is not present, then the method 1200
cycles back to 1205 where tracking based on the position of the sun
continues. However, if at 1220 it is determined that a stow event
is present, at 1225 the bellows 300 of one or more trackers 100 are
inflated and/or deflated to generate a stowed configuration for the
one or more trackers 100.
[0127] In various embodiments, a stow configuration of a tracker
100 can include various suitable configurations. For example, in
some embodiments, a stow position for an actuator can be a flat or
neutral position N, or maximum tilt positions A, B (see FIG. 2). In
some embodiments, a stow at maximum tilt positions A, B can include
pressurizing the tracker against a stop to rigidly fix the tracker
100 at one of the maximum tilt positions A, B. In other words, a
bellows 300 opposing the stop can be inflated to force the actuator
101 or other portion of the tracker 100 against the stop. The
non-opposing bellows 300 can be fully deflated in some embodiments
to allow for the opposing bellows 300 to provide maximum force
against the stop.
[0128] In further embodiments, the bellows 300 of one or more
actuators 101 can be inflated to an equilibrium to rigidly fix the
bellows 300 in a desired configuration. For example, in some
embodiments, inflation of both bellows 300E, 300W of an actuator to
a maximum fill pressure can generate a flat stow or a stow in the
neutral configuration N (see FIG. 2).
[0129] Returning to the method 1200 of FIG. 12, at 1230 sensing
data is obtained from one or more row controller sensors and/or one
or more solar tracker sensors, and at 1235, the sensing data is
processed to determine whether a stow event is still present. If at
1240 a determination is made that a stow event is still present,
then at 1245, tracker stow is maintained and the method 1200 cycles
back to 1230 where further sensing data is received and the state
of the solar tracking system 400 is monitored. However, if at 1240
a determination is made that a stow event is not still present,
then at 1250, stow is removed and tracking based on position of the
sun is resumed. The method 1200 then cycles back to 1210 where
monitoring for a further stow event occurs.
[0130] FIG. 13 illustrates a method 1300 of level-calibrating a
solar tracker 100 in accordance with an embodiment. For example,
when a solar tracker 100 is at the factory or set in place via
posts 104 (See FIGS. 1a, 1b and 2) or other suitable structures, it
can be desirable to calibrate or "zero" the system by determining
an output of inclinometers 603 (See FIG. 6) of one or more trackers
100 that should be defined as where the tracker 100 is level. The
method begins at 1310 where a leveling device is coupled with the
tracker 100 at a position that is parallel to the plane of the
photovoltaic panels 103. For example, in some embodiments, a
leveling device can be coupled to a top plate 330 of an actuator
101 or other suitable structure that is parallel to the plane of
the photovoltaic panels 103.
[0131] Additionally, a leveling device can comprise any suitable
device that can sense and/or present a level status, including a
bubble level, a digital level, plumb bob, or the like. In some
embodiments, a body of a leveling device can comprise opposing
faces disposed at a right angle (e.g. an angle bracket), which can
be desirable for coupling to squared portions of an actuator 101,
tracker 100, or the like. In further embodiments, the leveling
device can comprise a magnet, which can be desirable for coupling
to metal portions of an actuator 101, tracker 100, or the like.
[0132] Returning to the method 1300, at 1320 one or more bellows
300 of one or more actuators 101 are inflated and/or deflated to
move the photovoltaic cells 103 toward a level position, and if it
is determined at 1330 that a level state has not yet been attained
the one or more bellows 300 of one or more actuators 101 are
further inflated and/or deflated to further move the photovoltaic
cells 103 toward a level position. However, where it is determined
at 1330 that a level status has been obtained, then the current
inclinometer reading is defined or set as being level for the
photovoltaic cells 103 of the tracker 100.
[0133] For example, setting a current inclinometer reading as being
level for the photovoltaic cells 103 of the tracker 100 can include
a manual input to a device at a row controller 380. Additionally,
in some embodiments, a wired or wireless connection with a row
controller 380 can communicate a level status or otherwise
facilitate calibration of the level status of a tracker 100.
[0134] The described embodiments are susceptible to various
modifications and alternative forms, and specific examples thereof
have been shown by way of example in the drawings and are herein
described in detail. It should be understood, however, that the
described embodiments are not to be limited to the particular forms
or methods disclosed, but to the contrary, the present disclosure
is to cover all modifications, equivalents, and alternatives.
[0135] In some embodiments, the bellows 300 can be in the form of
an elastic vessel which can expand with the introduction of a
pressurized fluid, and which can collapse or shrink when the
pressurized fluid is released. The term `bellows` as used herein
should not be construed to be limiting in any way. For example the
term `bellows` as used herein should not be construed to require
elements such as convolutions or other such features (although
convoluted bellows 300 can be present in some embodiments). As
discussed herein, bellows 300 can take on various suitable shapes,
sizes, proportions and the like.
[0136] It should be noted that the figures are not drawn to scale
and that elements of similar structures or functions are generally
represented by like reference numerals for illustrative purposes
throughout the figures. It also should be noted that the figures
are only intended to facilitate the description of the preferred
embodiments. The figures do not illustrate every aspect of the
described embodiments and do not limit the scope of the present
disclosure.
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