WO2020198579A2

WO2020198579A2 - Roll-formed solar canopy structures and foundation structures and methods

Info

Publication number: WO2020198579A2
Application number: PCT/US2020/025194
Authority: WO
Inventors: Frank Carl OUDHEUSDEN; Christopher Thomas Needham
Original assignee: Fcx Solar, Llc
Priority date: 2019-03-27
Filing date: 2020-03-27
Publication date: 2020-10-01
Also published as: WO2020198579A3

Abstract

Solar canopy structures are composed of multiple solar panels and used to collect solar energy. The geometry of the solar panels within a solar canopy structure is modified to reduce wind loading on the structure. The geometry is modified by slightly tilting the individual solar panels in opposite directions. Wind loading on the unique solar panel geometry is tested using a wind tunnel to obtain actual wind loads instead of estimated wind loads. Reduced wind loads lead to reduced loads on the support structure, therefore lighter weight members can be used to construct the support structure. Smaller foundation structures can be used to support solar canopy structures with these alterations. Foundation structures can include an above grade ballasted foundation, a below grade spread footer foundation, a driven pile foundation, a helical pile foundation, or a ground screw foundation.

Description

ROLL-FORMED SOLAR CANOPY STRUCTURES AND

FOUNDATION STRUCTURES AND METHODS

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62/824,884, filed March 27, 2019, and U. S. Patent Application Serial No. 16/671 ,804, filed November 1 , 2019, which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present application is related to a solar canopy system and foundation systems.

BACKGROUND

[0003] The present disclosure relates to foundations of solar canopy systems, which can be installed in a multitude of different configurations to elevate

photovoltaic (PV) panels above ground. In addition to providing solar power, solar canopy systems can function to provide shade. For example, a solar canopy system may cover a parking surface, drive aisles, outdoor market, or pedestrian space. In other examples, a solar canopy system may cover railways, water canals, or any other environment that requires access from below the canopy.

[0004] Many solar canopy systems use some combination of hot rolled steel members (HSS tubes, I-beams, etc.) or custom welded components in combination with cold rolled module purlins or aluminum extrusions for module support. The use of hot rolled members is primarily driven by the relatively high wind loads PV canopies are designed to withstand and the drive toward minimizing the number of foundations used for a given canopy system. Generally, hot rolled members and custom truss members are capable of supporting higher loads than cold rolled steel members.

[0005] One obstacle to cost reduction of PV structures is the secondary operations required to convert hot rolled steel members into usable components.

This secondary operation work requires additional fabrication, welding, shipping, handling, and corrosion protection steps that add significant costs to the raw material cost of the canopy and thus drive total material cost higher. However, using current manufacturing techniques, it is not feasible to produce cold rolled members that are large enough to support the load of the solar canopy systems. Supporting beams, for example, currently use 2-3 times the volume of steel that is feasible to produce with current cold rolling processes. Accordingly, although cold rolling has the advantages described above over hot rolling, existing solar canopy systems are not designed to make use of these advantages.

[0006] A solar canopy system is a structure that typically has a larger span compared to other types of solar structures (e.g., fixed-tilt ground mounts, trackers, rooftop). An example of a conventional PV canopy structure is shown in Figure 1 (hereafter referred to as the“monoslope PV canopy 1”). As shown in Figure 1 , a vertical post 2 extends above a grade 3 and is anchored below the grade 3 by a foundation 4. One or more solar panels 5 are supported on a beam 6 by purlins 7 extending between the panels 5 and the beam 6. The beam 6, in turn, is mounted on the post 2 at an angle.

[0007] In Figure 1 , the vertical post 2 is typically composed of a hot-rolled member such as an I-beam or hollow structured section tube (“HSS tube”), although other hot rolled sections or truss designs can be used as well. The beam 6, which may be supported by one or more posts along its span length, is also composed of hot rolled members or truss designs. Finally, modules may be supported by module rails which are typically positioned at right angles to the beams and span over multiple beams through 1 or more connected module rails. These rails are typically the only components to be cold rolled steel members, although extruded aluminum is also used in some designs primarily for installation labor considerations. A number of different bracket designs and other fastening methods are employed to connect all steel members together into a PV canopy structure.

[0008] The structure of the monoslope PV canopy 1 may be found in the American Society of Civil Engineers Standard for Minimum Design Loads for

Buildings and Other Structures, ASCE/SEI 7-10 (hereafter referred to as ASCE 7-10) in Figure 27.4-4 for monoslope free roofs. It is well accepted within the solar power industry that the wind pressures prescribed in ASCE 7-10, Figure 27.4-4, are representative of the real world loading of these structures. For this reason, the largest suppliers of PV canopy structures do not typically utilize any wind tunnel testing in the design of their products. [0009] Under current practice, the wind loading coefficients prescribed for canopy structures with two or more non-parallel planes of solar panels can result in higher wind loading and thus higher costs than the single plane of solar panels designs based on the wind loading coefficients shown in ASCE 7-10, Fig. 27.4-4. Therefore, there is a need for a design methodology for canopy support structures for two or more non-parallel planes of solar panels based on determining the net instantaneous wind loading across the total combined area of the nonparallel planes of solar panels.

[0010] A solar canopy system has a foundation (e.g., foundation 4) that supports the larger span structure. The installation of a suitable foundation may require excavating a column several feet across and a dozen or so more feet deep into the ground, to provide a suitable structure that can support forces and moments imparted on the foundation by the solar canopy system and environmental conditions. A“pier” type foundation is typically used for most solar canopy systems. Pier foundations are relatively expensive compared to other types of foundations. For example, installing a pier foundation requires large, specialized equipment and suitable site properties (e.g., soil, ground slope) for excavating the foundation and hauling any excavated materials away from the site.

[0011] The cost prohibitive expense to install foundations of solar canopy systems drives a system designer to maximize the square footage of solar panel surfaces attributed to each foundation structure, which increases foundation loading and thus foundation size. This negative feedback exists where cost prohibitive foundations drive further canopy structure costs as designers try to optimize around expensive pier foundations. As such, there is a need for improved designs for foundations of solar canopy systems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a side elevation view of a solar canopy system including a plurality of single, parallel plane photovoltaic solar panels.

[0013] Figure 2A illustrates an example embodiment of a solar canopy system.

[0014] Figure 2B illustrates a top view of the first and second solar panels.

[0015] Figure 3 illustrates another example embodiment of a solar canopy system. [0016] Figure 4 illustrates an example embodiment of a solar canopy system including a concrete pier foundation.

[0017] Figure 5 illustrates an example embodiment of a solar canopy system including an above grade ballasted foundation.

[0018] Figure 6 illustrates an example embodiment of a solar canopy system including a below grade spread footer foundation.

[0019] Figure 7 illustrates an example embodiment of a solar canopy system including a driven pile foundation.

[0020] Figure 8 illustrates an example embodiment of a solar canopy system including a helical pile foundation.

[0021] Figure 9 illustrates an example embodiment of a solar canopy system including a ground screw foundation.

[0022] Figure 10 is a flowchart illustrating a process for designing a photovoltaic system,

[0023] Figs. 11 A-11 B illustrate example wind loading on a solar canopy. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. The terminology used in the description herein is for the purpose of describing particular

embodiments only and is not intended to be limiting of the invention.

[0025] As used in the description and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The words "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The word "comprises" and/or "comprising," when used in this

specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0026] The words "right," "left," "lower" and "upper" designate directions in the drawings to which reference is made. The words "inwardly" and "outwardly" refer to directions toward and away from, respectively, the geometric center of the solar canopy, and designated parts thereof. The terminology includes the words noted above, derivatives thereof and words of similar import.

[0027] Although ordinal words such as“first” and“second” are used herein to describe various elements, these elements should not be limited by these words. These words are only used to distinguish one element from another. For example, a first panel could be termed a second panel, and, similarly, a panel tube could be termed a first panel, without departing from the scope of the present invention.

[0028] As used herein, the words "if may be construed to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" may be construed to mean "upon determining" or "in response to determining" or "upon detecting [the stated condition or event]" or "in response to detecting [the stated condition or event]," depending on the context.

Solar Canopy System

[0029] The following description is directed towards various embodiments of a solar canopy system in accordance with the present disclosure. The present disclosure generally relates to a solar canopy system and methods for reducing canopy support structure design loadings, which allow for incorporating various alternative foundation designs. Specifically, the disclosure relates to a solar canopy system having two or more nonparallel solar panel assemblies having a support structure design based on instantaneous time averaging of the measured wind loadings of the two or more nonparallel solar panels, which can be supported by different foundation structures or configurations.

[0030] Methods and structures for reducing the size of a foundation for a solar canopy system are described below. In particular, these methods include reducing wind loading by performing wind load testing in a wind tunnel, reducing the weight of the overall structure by using cold rolled metal for some of the support structure, or cantilevering the solar canopy system structure over ground that is unsuitable for placement of a concrete pier foundation.

[0031] One obstacle to cost reduction of solar photovoltaic (PV) canopy structures is the wind loading prescribed by building codes. Currently, most canopy structure vendors in the industry do not utilize wind tunnel testing for measuring the wind loading on coplanar panel assemblies. Wind tunnel testing is discouraged because testing on a traditional structure does not yield a useful decrease in loading compared to the prescribed loads found in the code.

[0032] Here wind tunnel testing will provide a benefit because the geometry of the solar panels is altered. The solar canopy structure is altered by tilting each solar panel of the solar canopy structure. Furthermore, the reduced loading made possible by the wind tunnel testing process described herein enables a designer to obtain realistic wind loading values for solar canopy structures with unusual geometry. The reduced loading made possible by the wind tunnel testing process described herein enables different designs to the canopy support structure. For example, an advantage of realistic wind loading values is a decrease in the load, this decreased load allows portions of the canopy support structure to be built using cold rolled components which are lighter and less expensive.

[0033] Referring to the drawings in detail, where like numerals indicate like elements throughout, Figure 2A shows an example embodiment of a solar canopy 10 where the solar panels are tilted from the horizontal axis. The disclosed solar canopy 10 comprises a solar panel assembly 12 supported by and coupled to a solar panel assembly support structure 14 as further described below. The solar panel assembly 12 comprises at least a first solar panel 16 with a total wind exposed first solar panel surface area and a second solar panel 18 with a total wind exposed second solar panel surface area. The solar panel assembly 12 may have one or more additional solar panels, such as a third solar panel 20 with a total wind exposed third solar panel surface area. The solar panel assembly 12 can have a rectilinear array of solar panels including the first, second and third solar panels 16, 18, 20. The total number of solar panels comprising the array is a design choice based on the desired electrical output of the assembly. Typically, the solar panel assembly 12 includes at least six adjacent rows with three panels per row but could have more than six rows or less than six rows. Figure 3 illustrates another example

configuration of the solar panel assembly 12.

[0034] The second solar panel 18 is coupled to the first solar panel 16 such that the second solar panel 18 is oriented nonparallel with respect to the first solar panel 16. The third solar panel 20 can be oriented nonparallel with respect to the first solar panel 16, the second solar panel 18, or both the first and second panels 16, 18. For example, the first and second solar panels 16 and 18 are tilted about 5 to 7 degrees from the horizontal, rotated around an axis that is parallel to a surface of each solar panel and perpendicular to a longitudinal axis of the solar canopy 10.

[0035] For example, Figure 2A shows that the solar canopy 10 can have a longitudinal axis 41 , extending along a length of the solar canopy approximately parallel to the ground. As shown in Figure 2B, which is a schematic illustrating a top view of the first and second solar panels 16, 18, the first and second solar panels can each have an axis 43. The axis 43 is transverse to a top surface of each panel and substantially perpendicular to the longitudinal axis 41 of the solar canopy. Each panel can be tilted as if rotated around the axis 43, forming a small angle between a top surface of each panel and the longitudinal axis 41. The first solar panel 16 can be tilted in a counter clockwise direction and the second solar panel can be tilted in a clockwise direction, or the first panel 16 can be tilted clockwise while the second panel is tilted counter-clockwise. The degree of tilt can be more or less than the about 5 to 7 degrees. The third solar panel 20 may be tilted parallel to the first solar panel; alternatively, the third solar panel 20 may be oriented nonparallel with respect to the first solar panel 16 and tilted in the counter clockwise direction at an angle different than the tilt angle of the first solar panel 16. The solar panels can be tilted to create a wave effect.

[0036] The solar panels can be tilted more or less than 5 to 7 degrees, and each panel can have a different angular tilt. According to another embodiment, a first solar panel is tilted from the horizontal and a second solar panel, coupled to the first solar panel, is substantially parallel to the horizontal plane of the ground or a horizontal plane of the solar panel assembly support structure 14.

[0037] One advantage of changing the camber of the solar panels is to reduce wind loading on the solar panels when they are arranged in a solar canopy. When subjected to wind loading, the solar panel assembly 12 depicted in Figure 2A and

Figure 3 has an effective solar panel assembly wind loading that is less than a sum of effective wind loading on each solar panel if the panel wind loadings are determined individually. Calculating the sum of the wind load for multiple panels arranged together is a typical technique for calculating the total wind load on multiple panels. For example, the effective assembly wind load for this configuration for the first solar panel 16 and the second solar panel 18 is less than a sum of a wind load determined on the first panel 16 (referred to herein as a“first solar panel effective wind loading”) and a wind loading determined on the second panel 18 (referred to herein as a“second solar panel effective wind loading”). The actual solar panel assembly wind loading for the disclosed solar canopy is determined by wind tunnel testing of the solar panel assembly 12 whereby instantaneous time averaging of the measured pressures of two or more nonparallel solar panel assemblies determines the net wind loading as further discussed below.

[0038] The solar panel assembly support structure 14 comprises a post 30 having a post bottom end 32 and a post top end 34 spaced from the post bottom end 32. A cross beam 36 is attached to and supported by the post top end 34. The post bottom end 32 may be embedded directly in the ground or may be attached to a foundation 40 in the ground. A plurality of purlins 42 extend between the cross beam 36 and the first, second and third solar panels 16, 18, 20 and support and couple the first, second and third solar panels 16, 18, 20 to the cross beam 36. The purlins 42 vary in length in order to achieve the desired tilt of the solar panels 16, 18, 20. The purlins 42 can have a variety of well known geometric shapes and are typically roll formed shapes.

[0039] The actual load applied by the disclosed solar panel assembly 12 through the purlins 42 and cross beam 36 to the post 30, when the solar panel assembly 12 is subject to a wind loading, is less than a design load for a traditional solar panel assembly 12 subject to the wind loading based on a sum of wind loading on each solar panel. For example, for a three panel assembly 12, the design load for wind loading on the assembly 12 is based on a sum of wind loading on the first solar panel (a first solar panel net pressure), a wind loading on the second solar panel (a second solar panel net pressure), and a wind loading on the third solar panel (a third solar panel net pressure), when the first solar panel net pressure, the second solar panel net pressure and the third solar panel net pressure load are determined independently.

[0040] Although various embodiments of solar canopies are shown in Figs. 2 and 3, the invention is not limited to these canopies. The size of the solar panel assembly is a design choice based on the desired electrical output of the assembly. Other embodiments may include additional or fewer solar panels than shown in these figures. Similarly, the number and distribution of the posts, cross beams and purlins comprising the solar panel assembly support structure is based on a determination of the net instantaneous wind loading across the total combined area of the nonparallel planes of solar panels. [0041] The design methodology for the disclosed canopy support structures having two or more nonparallel planes of solar panels is based on determining the net instantaneous wind loading across the total combined area of the nonparallel planes of solar panels. Referring to Figures 11 A and 11 B, force coefficient GCP and moment coefficients GCMHY, GCiviy, defined by the following equations are calculated from wind tunnel pressure data and are used to size all components of the solar panel assembly support structure.

Where,

is the force normal to the top surface of the PV

F normal

modules;

is the moment about the top of post (center of the cross

FI top of post

beam);

is the moment about the grade;

Mgrade qH is the ASCE 7 velocity pressure at a height (H) of < 4.5 m in open terrain;

A is the averaging area (No. of panels multiplied by 2 m²); and

L is the nominal chord length ( e.g 6 m for a three-panel system, 8 m for four-panel system, or 12 m for a six- panel system).

[0042] The wind tunnel pressure data is obtained by simultaneously measuring the pressure at pressure taps embedded in the surfaces of panels comprising the solar panel assembly to be supported by the solar panel assembly support structure. The wind pressure data is then used to calculate actual wind loads on the solar panel assembly 12.

[0043] An actual wind load applied by the solar panel assembly 12 through the purlins 42 and cross beam 36 to the post 30 is less than a design wind load for the solar panel assembly 12 based on a sum of wind loading on each solar panel. The reduced actual wind load applied to the support structure 14 allows the support structure 14 to be manufactured using less material than is used by support structures for typical solar panel assembly designs. In particular, the reduced load on the support structure can decrease the size of structural components needed by the support structure into a domain in which the structural components can feasibly be manufactured by cold rolling instead of hot rolling.

[0044] The largest suppliers of PV canopy structures do not typically utilize wind tunnel testing in the design of their products. Under current practice, the wind loading coefficients prescribed for canopy structures with two or more nonparallel planes of solar panels can result in higher wind loading and thus higher costs than the single plane of solar panels designs based on the wind loading coefficients shown in ASCE 7-10, Figure 27.4-4.

[0045] For example, the reduced wind load on the support structure can decrease the size of structural components of the support structure. Smaller structural components mean that the structural components can be manufactured by cold rolling instead of hot rolling. Cold rolled members weigh less than hot rolled members, therefore decreasing the total dead load of the support structure.

[0046] At least a portion of the support structure 14 can be manufactured using cold rolled structural members. For example, cold rolled members can be used for the vertical post 30 and horizontal beam 36. Other components can be

manufactured by cold rolling, including a return tab on flanges, web stiffeners, or fully boxed or closed members. Cold rolled members are more cost effective and lighter weight than hot rolled members.

[0047] Cold rolling can beneficially eliminate secondary fabrication steps that would be required if the components were produced by hot rolling. For example, hot rolled components typically require secondary fabrication steps such as adding fastener holes; adding stiffeners, gussets, or other load distributing features to beams or channels; or adding fastening plates or similar welded features. Some hot rolled components also need corrosion protection provided by, for example, hot dip galvanizing or painting.

[0048] Shapes of the structural components can also be more easily

customized for a given application by cold rolling than when the components are produced by hot rolling. Hot rolled components are typically standardized and application agnostic, and may therefore not be tailored to the specific design needs of a particular solar canopy. In contrast, customized cold rolled components can be designed and manufactured to meet the needs of a particular canopy structure. Accordingly, cold rolled components can be designed to meet design specifications without significantly exceeding the specifications, resulting in less material used in the canopy structure. The reduced amount of metal used to build the structure decreases the cost and weight of the structure.

[0049] According to one embodiment, the support structure 14 can be manufactured by cold rolling. For example, in Figure 2A the parts that can be manufactured by cold rolling are the post 30, the horizontal crossbeam 36, the purlins 42. Additionally, the flange return tab, web stiffener, and the fully boxed member can be manufactured by cold rolling. This list is not exclusive, other components of the solar panel system can also be manufactured by cold rolling due to reduced wind loads.

[0050] Therefore, changing the geometry of the solar panels within a solar canopy system and then testing the actual wind loads experienced by the solar canopy system can yield lower actual wind loads that are used in the design of a solar canopy wind system. Lower actual wind loads can result in support structure members being constructed with different materials than the typical hot rolled metal. One such material is cold rolled metal. Lighter weight materials and smaller wind loads mean that smaller foundations can be designed. Such smaller foundations are more cost effective and easier to construct.

[0051] Solar panels in a solar panel system according to one embodiment can be arranged in rectilinear arrays, containing for example six rows with three solar panels per row.

Foundation Designs of Solar Canopy Systems

[0052] A primary challenge of designing solar canopy foundations is the tremendous forces and moments applied to the structure at grade from canopy designs currently employed. For example, moments at grade for a typical 6P monoslope canopy (see, e.g., Figure 1 ) can be well over 100,000 ft-lbs.

Economically feasible ground screws, helical piles, and driven piles typically do not provide sufficient load bearing capacity in most soil types to allow their use on large scale projects. Accordingly, a reduction in foundation loading is needed in the industry to reduce the cost of solar canopy support structures.

[0053] One method to increase the applicability of alternate foundations is to design canopy structures where forces and moments at grade are reduced by limiting environmental loading through site selection. Selecting a site where potential wind loads might be lower would decrease the loading on foundations.

[0054] Another method to increase applicability of alternate foundations is to make changes to the geometry of the canopy structure that result in favorable environmental loading, in particular wind loading, on individual foundation structures. These changes may or may not reduce overall solar panel system energy production capacity per foundation and may or may not require wind tunnel testing to validate the reduced loading per foundation that results from geometry changes. An example of a canopy structure geometry change that may reduce design loading is shown in Figure 2A.

[0055] Another method to increase applicability of alternate foundations is to physically couple more than one foundation together in order to address

environmental loading at another location than at grade. An example of this approach is to utilize a“long span canopy” as shown in Figure 3. This configuration cantilevers the solar canopy over locations with unsuitable soils or site geometry (such as a steep hillside). Figures 2 and 3 are nonlimiting examples because other configurations that reduce foundation loading exist and are within the spirit of this disclosure.

[0056] The present disclosure demonstrates multiple alternate foundation designs that can be utilized on PV canopy structures, and the design methods to allow their use in a cost effective way. As indicated above, current industry standards include using pier type foundations in a solar canopy system to support canopy structures. Figure 4 illustrates an example of a solar canopy system including a concrete pier 44 foundation. As mentioned above, installing a concrete pier 44 is laborious and cost prohibitive. For example, installation requires specialized equipment to excavate a site, haul away the excavated material, and pour concrete into the excavation to form the pier foundation. [0057] As such, the widespread use of solar canopy structures is oftentimes impractical, especially in site locations that are not readily accessible for specialized equipment or where ground conditions are not suitable for deep and/or wide excavations. For example, a hillside that receives an abundance of solar energy could benefit from a solar canopy system. However, a solar power system designer may forego even considering such a design because the site is too remote and has a rocky ground that is not suitable for installing a pier type foundation. Thus, the benefits of solar power generated from solar canopy systems are oftentimes lost due to prohibitive construction costs.

[0058] The disclosed embodiments include various types of foundations enabled by the solar canopy systems described herein. They are possible because of reductions in wind loading as described above and reductions in the dead load of the structure due to lighter weight structural members of the support structure. For example, the embodiments of the solar canopy 10 of Figure 2A (and Figure 3) allow for various foundation designs that are not available for conventional solar canopy systems.

[0059] One alternate foundation design that can significantly cut cost for solar canopy structures over existing pier designs is a ballasted foundation. This design can be employed as either an above grade ballasted foundation 52 (exists

substantially above an existing grade) or a spread footer 62 below grade. Figure 5 illustrates an example embodiment of a solar canopy system 10 including an above grade ballasted foundation 52. Figure 6 illustrates an example embodiment of a solar canopy system 10 with a below grade spread footer foundation 62. Above grade ballasted foundations 52 and below grade spread footer foundations are less expensive to construct than a concrete pier foundation. They require fewer building materials and reduced excavation and removal of onsite soils.

[0060] In some embodiments, the disclosed types of foundations may have a design that is pre-cast or cast in place. Ballasted foundations are sometimes specified for fixed-tilt ground mount solar projects where geotechnical concerns preclude other foundation types but are generally not cost effective on the majority of projects. An above grade foundation can be useful in sites where removal and disposal of onsite soils is difficult because the soil is contaminated or because removal of onsite soils would be cost prohibitive. [0061] Another alternate foundation design that can reduce costs and improve utilization of solar canopy systems over a pier design is a driven pile foundation 72. For example, Figure 7 illustrates an example embodiment of a solar canopy system 10 including a driven pile foundation 72. Driven pile foundations 72 are typically employed by fixed-tilt ground mount PV structures where individual foundation loading can be an order of magnitude below that of typical PV canopy designs. Altering the geometry of the solar panels as disclosed above and in Figure 2A, decreases the size of the support structure needed and the foundation loading. Cantilevering over unsuitable soils can provide the needed reduction in foundation loading as well. Driven piles are easier to construct than concrete pier foundations. They require less equipment and fewer materials. Thus, the disclosed solar canopy systems 10 allow for utilizing driven pile foundation 72 designs to provide the resulting benefits of solar canopy systems that are otherwise not available for some site conditions.

[0062] Another alternate foundation design that may reduce costs over a concrete pier design is the use of a helical pile 82 or ground screw 92 type foundation. For example, Figure 8 illustrates an example embodiment of a solar canopy system 10 with a helical pile 82 foundation. Figure 9 illustrates an example embodiment of a solar canopy system 10 with a ground screw foundation 92. These types of foundations may require one or more helical piles 82 or ground screws 92 per foundation location to resist environmental loads depending on the structural design.

[0063] Helical pile 82 and ground screw 92 foundations are sometimes used on fixed-tilt ground mount and tracker style PV support structures but not by

conventional solar canopy systems. Helical pile 82 foundations and ground screw 92 foundations are ideally suited to locations where large equipment cannot be brought into the site. Altering the geometry of the solar panels as in Figure 2A, decreasing the size of the support structure and cantilevering over unsuitable soils can provide the needed reduction in foundation loading to enable the use of helical piles 82 and ground screw 92 foundations. Thus, again, the disclosed solar canopy systems allow for utilizing helical pile 82 or ground screw 92 foundation designs to offer the resulting benefits of solar canopy systems that are otherwise not available for conventional systems. [0064] Figure 10 is a flowchart illustrating a process for designing a photovoltaic system, according to some embodiments. As shown in Figure 10, a model of a photovoltaic system is constructed at block 1002. The model includes a plurality of photovoltaic modules, a support system supporting the plurality of photovoltaic modules, and a foundation. At block 1004, the model is tested in a wind tunnel, where wind is applied to the system model. During the test, at block 1006, a magnitude of wind loads acting on the photovoltaic model is recorded. At block 1008, an actual wind load that a photovoltaic system would experience during a wind event is calculated. At block 1010, a load value for a foundation of the photovoltaic system is calculated, taking into account a weight of any components supported by the foundation (such as the photovoltaic modules and the support system) as well as the actual calculated wind load. Finally, at block 1012, an appropriate foundation type is selected for the calculated load value.

[0065] Although the above description describes certain embodiments and the best mode contemplated, no matter how detailed the above appears in text, the embodiments can be practiced in many ways. Details of the systems and methods may vary considerably in their implementation details, while still being encompassed by the specification. As noted above, particular terminology used when describing certain features or aspects of various embodiments should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification, unless those terms are explicitly defined herein. Accordingly, the actual scope of the invention encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the embodiments under the claims.

[0066] The language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this description. Accordingly, the disclosure of various embodiments is intended to be illustrative, but not limiting.

Claims

CLAIMS I/We claim:

1. A photovoltaic system comprising:

a solar panel assembly comprising:

a first solar panel having a total wind exposed first solar panel surface area; and

a second solar panel having a total wind exposed second solar panel surface area, the second solar panel coupled to the first solar panel and the total wind exposed second solar panel surface area having a nonparallel orientation with respect to the total wind exposed first solar panel surface area, and

a solar panel assembly support structure coupled to the solar panel assembly, wherein:

the solar panel assembly support structure is designed to support an actual load applied to the solar panel assembly support structure by the solar panel assembly when the solar panel assembly is subject to a wind loading,

the actual load is less than a design load for the solar panel assembly subject to the wind loading based on a sum of a first solar panel net pressure for the first solar panel and a second solar panel net pressure for the second solar panel, and

a foundation structure coupled to the solar panel assembly support structure and anchored into a ground to transfer loads from the solar power assembly and the solar panel assembly support structure to the ground, the foundation structure including an above grade ballasted foundation, a below grade spread footer foundation, a driven pile foundation, a helical pile foundation, or a ground screw foundation.

2. The photovoltaic system of claim 1 , wherein the first photovoltaic module is tilted in a counter clockwise direction from horizontal and the second photovoltaic module is parallel with a horizontal plane or tilted in a clockwise direction from horizontal.

3. The photovoltaic system of claim 1 , wherein the support system is manufactured by cold rolling.

4. The photovoltaic system of claim 1 , wherein the first solar panel is adjacent to the second solar panel.

5. The photovoltaic system of claim 1 , wherein the support system comprises a post coupled between the foundation structure and the solar panel assembly, the post supporting the collection of photovoltaic modules above a surface of the ground.

6. The photovoltaic system of claim 1 , wherein the photovoltaic modules are coupled to distribute a dead load of the photovoltaic modules and the support system between the first foundation structure and the second foundation structure, thus decreasing the load on the first foundation structure.

7. The photovoltaic system of claim 1 , wherein the support structure is cantilevered over an area where construction of a large foundation is not suitable.

8. A photovoltaic canopy system, comprising:

a collection of photovoltaic modules including a first photovoltaic module and a second photovoltaic module that is disposed nonparallel to the first photovoltaic module;

a support system supporting the collection of photovoltaic modules; and an above grade ballasted foundation supporting the support system and the photovoltaic modules.

9. A photovoltaic canopy system, comprising:

a support system supporting the collection of photovoltaic modules; and a below grade spread footer foundation supporting the support system and the photovoltaic modules.

10. A photovoltaic canopy system, comprising:

a support system supporting the collection of photovoltaic modules; and a driven pile foundation supporting the support system and the photovoltaic modules.

11. A photovoltaic canopy system, comprising:

a support system supporting the collection of photovoltaic modules; and a helical pile foundation supporting the support system and the photovoltaic modules.

12. A photovoltaic canopy system, comprising:

a support system supporting the collection of photovoltaic modules; and a ground screw foundation supporting the support system and the

photovoltaic modules.

13. A method of designing a photovoltaic system, the method comprising: constructing a model of a photovoltaic system within a wind tunnel, the model comprising:

a plurality of photovoltaic modules;

a support system supporting the plurality of photovoltaic modules; and

a foundation;

running a test of the photovoltaic system within the wind tunnel;

recording a magnitude of a plurality of wind loads acting on the photovoltaic model during the test; calculating an actual wind load that a photovoltaic system would experience during a wind event;

calculating a load value for a foundation of a photovoltaic system; and selecting an appropriate foundation type for the calculated load value.

14. The method of claim 13, wherein the foundation type includes any of an above grade ballasted foundation, a below grade spread footer foundation, a driven pile foundation, a helical pile foundation, or a ground screw foundation.

15. The method of claim 13, wherein the support system is manufactured by cold rolling.

16. The method of claim 13, wherein a first photovoltaic module is tilted in a counter clockwise direction from horizontal and a second photovoltaic module is parallel with a horizontal plane or tilted in a clockwise direction from horizontal.

17. A method for reducing wind loading on a photovoltaic system, the method comprising:

arranging a first photovoltaic module and a second photovoltaic module adjacent to each other;

tilting the first photovoltaic module so that the first photovoltaic module is not horizontal with the ground surface, the first photovoltaic module tilted at an angle from the ground surface; and

arranging the second photovoltaic module so that the second photovoltaic module is not tilted at the same angle as the first photovoltaic module.

18. The method of claim 17, wherein the first photovoltaic module and the second photovoltaic module are supported by a support structure, the support structure comprising one or more members that are manufactured by cold rolling.

19. The method of claim 18, wherein the first photovoltaic module and the second photovoltaic module, and the support structure are supported by a foundation, the foundation including any of an above grade ballasted foundation, a below grade spread footer foundation, a driven pile foundation, a helical pile foundation, or a ground screw foundation.

20. A solar canopy comprising:

a solar panel assembly comprising:

a second solar panel having a total wind exposed second solar panel surface area,

wherein the second solar panel is coupled to the first solar panel and wherein the total wind exposed second solar panel surface area has a nonparallel orientation with respect to the total wind exposed first solar panel surface area, and

a solar panel assembly support structure coupled to the solar panel assembly, the solar panel assembly support structure comprising one or more components manufactured by cold rolling;

wherein the solar panel assembly support structure is designed to support an actual load applied to the solar panel assembly support structure by the solar panel assembly when the solar panel assembly is subject to a wind loading, wherein the actual load is less than a design load for the solar panel assembly subject to the wind loading based on a sum of a first solar panel net pressure for the first solar panel and a second solar panel net pressure for the second solar panel, the first solar panel net pressure and the second solar panel net pressure determined independently.

21. The solar canopy of claim 20, wherein the solar panel assembly support structure comprises a post having a bottom end coupled to a foundation structure and a top end coupled to the solar panel assembly, wherein the one or more components manufactured by cold rolling comprise the post.

22. The solar canopy of claim 20, wherein the solar panel assembly support structure comprises a horizontal crossbeam coupled to the solar panel assembly, and wherein the one or more components manufactured by cold rolling comprise the crossbeam.

23. The solar canopy of claim 20, wherein the one or more components manufactured by cold rolling comprise at least one of a flange return tab, a web stiffener, or a fully boxed member.

24. The solar canopy of claim 20, wherein the solar panel assembly has a third solar panel with a total wind exposed third solar panel surface area, the third solar panel coupled to the second solar panel and having a nonparallel orientation with respect to the total wind exposed second solar panel surface area.

25. The solar canopy of claim 24, wherein the solar panel assembly is a rectilinear array of a plurality of solar panels including the first solar panel, the second solar panel and the third solar panel.

26. The solar canopy of claim 25, wherein the rectilinear array comprises at least an adjacent six rows with three solar panels of the plurality of solar panels per row.

27. The solar canopy of claim 20, wherein the first photovoltaic module is tilted in a counter clockwise direction from horizontal and the second photovoltaic module is parallel with a horizontal plane or tilted in a clockwise direction from horizontal.

28. The solar canopy of claim 27, wherein the solar panel assembly has a third solar panel with a total wind exposed third solar panel surface area, the third solar panel coupled to the second solar panel and tilted parallel to the first solar panel.

29. The solar canopy of claim 27, wherein the solar panel assembly has a third solar panel with a total wind exposed third solar panel surface area, the third solar panel coupled to the second solar panel, oriented nonparallel with respect to the first solar panel and tilted in the counter clockwise direction at another tilt angle different than the tilt angle of the first solar panel.

30. The solar canopy of claim 20, wherein the actual load applied to the solar panel assembly support structure is determined by a force coefficient GCP, a first moment coefficient GCMHY, and a second moment coefficient GCiviy defined by the following equations:

M top of post

GC M, Hy

q_H - A - L

M grade

GC_My =

q_H A - L

where,

F normal is a force normal to a top surface of the first or second solar panels;

M top of _po St is a moment about a top of the post (center of a cross beam);

Mgrade is a moment about a bottom of the post; qH is a velocity pressure at a height (H) of

< 4.5m in an open terrain;

A is a averaging area (Number of panels

multiplied by 2 m²); and

L is a nominal chord length, and

wherein the force coefficient GCP, the first moment coefficient GCMH_Y, and the second moment coefficient GCiviy are calculated from wind tunnel pressure data obtained by simultaneously measuring a pressure at a plurality of pressure taps embedded in a surface of the first and second solar panels.

31. The solar canopy of claim 20, wherein the plurality of purlins extend substantially vertically between the cross beam and the first solar panel and between the cross beam and the second solar panel and varying in length to achieve a desired tilt of the first and second solar panels.