Wind Loads on PV Arrays - S. K. Ghosh Associates

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S. K. Ghosh Associates Inc.

www.skghoshassociates.com

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Jason Ericksen, S.E.S. K. Ghosh Associates Inc.www.skghoshassociates.com

Solar Photovoltaic Systems Committee

Ronald LaPlante, S.E.Division of the State Architect – State of California

Wind Loads on PV Arrays

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Why are we here?

� Photovoltaic arrays are becoming more popular

� Codes and Standards do not address these directly

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Freestanding

Carports

Arrays

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Residential

Sloped relative to pitched roof

Flush-mounted on sloped roofs

Not covered in this discussion

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Commercial

Flat Roofs – not flush mounted

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ROADMAP

� Building Codes and Standards

� Freestanding Systems

� Flush-Mounted Systems on Sloped Roofs

� Low-Profile Systems on Flat Roofs

SEAOC Solar Photovoltaic Systems Committee report SEAOC PV2-2012

“Wind Design for Low-Profile Solar Photovoltaic Arrays on Flat Roofs”

Ron LaPlante

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ROADMAP


• IBC

• ASCE 7




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Building Codes and Standards

� 2009 IBC

• No provisions for ground or roof mounted PV arrays

� 2012 IBC

• No Provisions for ground mounted PV arrays

• New section for roof mounted PV arrays

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2012 IBC Chapter 15 – Roof Assemblies and Rooftop Structures

� 1509.7 Photovoltaic systems. Rooftop mounted photovoltaic systems shall be designed in accordance with this section.

1509.7.1. Wind Resistance. Rooftop mounted photovoltaic systems shall be designed for wind loads for components and cladding in accordance with Chapter 16 using an effective wind area based on the dimensions of a single unit frame.

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Building Codes and Standards

� ASCE 7-05 and ASCE 7-10

• No provisions specifically for ground or roof mounted PV arrays

• Provisions may be adapted to apply

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ASCE 7-05 and ASCE 7-10Freestanding Systems

� Open building? MWFRS

C&C

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ASCE 7-05 and ASCE 7-10Freestanding Systems

� Solid freestanding sign?

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ASCE 7-05 and ASCE 7-10Flush-Mounted Systems

� Standard building roof pressures?MWFRS

C&C

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ASCE 7-05 and ASCE 7-10Flush-Mounted Systems

� Solid attached sign?

This is a SOLID SIGN

Elevation Cross-Section

≤≤≤≤ 3 ft

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ASCE 7-05 and ASCE 7-10Sloped Systems on Flat Roofs

� Rooftop equipment?

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ROADMAP





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Freestanding Systems

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Freestanding SystemsICC AC428

� ICC Evaluation Service: Acceptance Criteria for modular framing systems used to support photovoltaic (PV) modules (ICC AC428)

� Just released -November 2012

www.icc-es.org/criteria/pdf_files/AC428.pdf

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Freestanding SystemsICC AC428 – Wind Loads

� 3.1.3.1.2 Freestanding System

• MWFRS elements provide support and stability for the overall structure

� lateral bracing, columns and primary beams

• C&C elements are those that do not qualify as MWFRS elements

� beams supporting PV modules and connections between the PV modules and the beams

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• MWFRS elements: Open buildings with monoslope roofs

� Section 6.5.13 using Figures 6-18A and 6-18D of ASCE 7-05 for 2009 and 2006 IBC

� Section 27.4.3 using Figures 27.4-4 and 27.4-7 of ASCE 7-10 for 2012 IBC

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• C&C elements: Open buildings with monoslope roofs

� Section 6.5.13 using Figure 6-19A of ASCE 7-05 for 2009 and 2006 IBC

� Section 27.4.3 using Figure 30.8-1 of ASCE 7-10 for 2012 IBC

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Components and Cladding

Main Wind-Force Resisting System

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Freestanding SystemsICC AC428 – Considerations

� ASCE 7 provisions for Monoslope Free Roofs

• Figures limited to θ ≤ 45°

� Shielding has not been considered

� Size effects have not been considered

Roof Angle

θθθθLoad Case

Wind Direction, γγγγ = 0° Wind Direction, γγγγ = 180°

Open Wind Flow Obstructed Wind Flow Open Wind Flow Obs tructed Wind Flow

CNW CNL CNW CNL CNW CNL CNW CNL

0°A 1.2 0.3 -0.5 -1.2 1.2 0.3 -0.5 -1.2B -1.1 -0.1 -1.1 -0.6 -1.1 -1.0 -1.1 -0.6

7.5°A -0.6 -1 -1 -1.5 0.9 1.5 -0.2 -1.2B -1.4 0 -1.7 -0.8 1.6 0.3 0.8 -0.3

15°A -0.9 -1.2 -1.1 -1.5 1.3 1.6 0.4 -1.1B -1.9 0 -2.1 -0.6 1.8 0.6 1.2 -0.3

22.5°A -1.5 -1.6 -1.5 -1.7 1.7 1.8 0.5 -1B -2.4 -0.3 -2.3 -0.9 2.2 0.7 1.3 0

30°A -1.8 -1.8 -1.5 -1.8 2.1 2.1 0.6 -1B -2.5 -0.5 -2.3 -1.1 2.6 1 1.6 0.1

37.5°A -1.8 -1.8 -1.5 -1.8 2.1 2.2 0.7 -0.9B -2.4 -0.6 -2.2 -1.1 2.7 1.1 1.9 0.3

45°A -1.6 -1.8 -1.3 -1.8 2.2 2.5 0.8 -0.9B -2.3 -0.7 -1.9 -1.2 2.6 1.4 2.1 0.4

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ROADMAP




• Modular Framing system

• Roof members


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Flush-Mounted Systems

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2012 IBC Chapter 15 – Roof Assemblies and Rooftop Structures

� 1509.7.1. Wind Resistance(rooftop mounted photovoltaic systems)

• All elements as components and cladding

• Effective wind area of single unit

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Flush-Mounted SystemsICC AC428

� ICC Evaluation Service: Acceptance Criteria for modular framing systems used to support photovoltaic (PV) modules (ICC AC428)

� Just released -November 2012

www.icc-es.org/criteria/pdf_files/AC428.pdf

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Flush-Mounted SystemsICC AC428 – Wind Loads

� 3.1.3.1.1 Flush-Mounted System

• All elements designed for C&C loads

� Chapter 6 of ASCE 7-05 using Method 2 (Analytical Procedure for Low-Rise Buildings) for the 2006 and 2009 IBC

� Chapter 26 and 30 of ASCE 7-10 using the Envelope Method prescribed in Chapter 30, Part I for the 2012 IBC

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Flush-Mounted SystemsICC AC428 - Wind Loads


• Internal pressure coefficient = 0

p = qh[(GCp) – (GCpi)]

p = qh(GCp)

• p ≥ 10 psf for the 2006 and 2009 IBC

• p ≥ 16 psf for the 2012 IBC

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Flush-Mounted SystemsICC AC428 - Conditions


• The distance between the roof or wall surface and the PV module must be between 2 and 10 inches

• PV modules shall not be installed within 10 inches of roof edge or ridge

2 in. ≤ dpv ≤ 10 in.

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Flush-Mounted SystemsICC AC428 - Conditions


• A minimum gap of 0.75 0.25 inch must exist between PV modules and adjacent rows of modules

• Building height limited to 60 ft

≥ 0.25 in.

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Modular Framing SystemsICC AC428

� Additional load requirements

• Snow

• Seismic

• Dead

• Roof Live

� Serviceability

• loads and limits

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Flush-Mounted SystemsSolar ABCS Report� Solar America Board for Codes and Standards

report: “Wind Load Calculations for PV Arrays”

Stephen Barkaszi, P.E.Florida Solar Energy Center

Colleen O’Brien, P.E.BEW Engineering

June 2010

www.solarabcs.org/about/publications/reports/wind-load/index.html

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Flush-Mounted SystemsSolar ABCS Report

• PV mounting structure and attachment to the roof

• PV modules and attachment to the mounting structure



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Flush-Mounted SystemsResource Comparison

2012 IBC 1509.7 ICC AC428 Solar ABCS

Internal Pressurecoefficient

NA GCpi = 0 ±0.10 ≤ GCpi ≤ ±0.30

Stand off distance

NA 2 in. ≤ dpv ≤ 10 in. dpv ≤ 6 in.

Distance to roof edge or ridge

NA dedge ≥ 10 in. NA

Gap between modules

NA gap ≥ 0.75 in. NA

Building Height NA ≤ 60 ft ≤ 60 ft

C&CAll members and

attachmentsAll members and

attachments

PV modules and attachment to the

mounting structure

MWFRS None NonePV mounting structure and attachment to the

roof

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Flush-Mounted SystemsSupporting Roof Members

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With PV Modules

WithoutPV Modules

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Additional Resource

� “Wind Load Analysis for commercial roof-mounted arrays”

Colleen O’Brien, P.E.BEW Engineering

David Banks, Ph.D.CPP Wind Engineering

June/July 2012

http://solarprofessional.com/article/?file=SP5_4_pg6_TOC

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Additional ResourceSolarPro Article

� Low-profile PV arrays on flat roofs

• DNV Wind Load Calculator

� Freestanding systems

• ASCE 7-05: Open buildings with monosloped roofs

• Results will be conservative for interior rows, but conducting wind tunnel tests in compliance with ASCE 7-05 guidelines can reduce this conservatism

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BREAK!

If you are encountering technical difficulties, please call (847) 991-2700

If you have any questions, please type them in

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Question and Answer Session




New SEAOC Document for Wind Design of Rooftop Solar Arrays

December 6, 2012Ronald LaPlante, S.E.

Division of State Architect – State of California

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SEAOC Solar Photovoltaic Systems Committee

Outline

� PV Committee and Scope

� Overview of SEAOC Solar PV Wind Design

Report

� Prescriptive Solar PV Wind Design Values

� Effective Wind Area

� Wind Tunnel Procedure

� Example Solar PV Problem

� Solar PV Code Development

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New SEAOC PV Committee Reports

Available at: http://www.seaoc.org/bookstore

52

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PV COMMITTEE AND SCOPE

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Formation of Committee

� Formed in September 2011 as subcommittee

of SEAOC Wind Committee

� Composed of:

� Structural Engineers

� Code Enforcement Agencies

� Wind Tunnel Experts

� Solar PV Industry Members

� NCSEA & ASCE 7 Wind Committee Members

� SEAOC Seismology Members

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Solar Photovoltaic Arrays Types

Flat Roofs

Carports Ground Mount

Sloped Roofs

Parking Garages

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Which Wind Loading Provisions Apply?

What about other installations?

ASCE 7

Open Buildings (ASCE 7-05 Figure 6-18,19) (ASCE 7-10 Figure 27.4-4, 30.8)

Enclosed Buildings – C&C(ASCE 7-05 Figure 6-11)(ASCE 7-10 Figure 30.4-2)

ICC AC 428

56

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Which Wind Loading Provisions Apply?

Flat Roofs – not flush mounted

Ground Mount - Sheltering

Parking Garages

Pitched Roofs – not flush mounted

Apply Kzt as if on cliff?

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Wind Tunnel Procedure

ASCE 7

Wind Tunnel Procedure (WTP)

What’s an appropriate wind tunnel study?

ASCE 7 WTP is written for specific building modeling, not generalized buildings with solar panels.

Should the WTP be peer reviewed?

Is there a minimum wind load?

Does building need to be modeled?

Roof zoning?

Etc…

58

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Failures do Occur

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OVERVIEW OF SEAOC SOLAR PVWIND DESIGN REPORT

60

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Goals for Solar PV Wind Report

� Develop report to address wind

design provisions for low-profile

solar PV arrays on flat roofs

� Establish wind design

coefficients similar to those in

ASCE 7 figures

� Report provides proposed

changes to ASCE 7-10,

references added for ASCE 7-

05 – equally applicable

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Goals for Solar PV Wind Report

� Define Effective Wind Area for

unique aspects of solar PV

arrays

� Define minimum Wind Tunnel

Procedure modeling

requirements and minimum

design loads

� Example Problem

62

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PRESCRIPTIVE SOLAR PV WIND DESIGN VALUES

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ASCE 7 Wind Design

ASCE 7

qh=0.00256KzKztKdV2Iand accounts for site parameters:• Kz – building exposure & height• Kzt – site topography• Kd – wind directionality• V – site wind speed

pressure=qhGCn

GCn accounts for aerodynamic effects.Need to create GCnfactors for solar PV so it is generalized for any site and building.

64

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Wind Tunnel Data

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� Understanding wind flow environment on roof

Wind Tunnel Data

66

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� Vortices form at roof corners

� Shear layer forms at roof edge

Wind Tunnel Data

67


Wind Tunnel Data

� Take the guesswork out

68

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Wind Tunnel Data

� Following test on 10 degree tilt, lift values (6Hx6H)

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Lift Coefficients 0°

Wind Tunnel Data

North

70

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Wind Tunnel Data

North

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Wind Tunnel Data

North

72

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Wind Tunnel Data

North

73



Wind Tunnel Data

North

74

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Wind Tunnel Data

North

75



Wind Tunnel Data

North

76

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Wind Tunnel Data

North

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Wind Tunnel Data

North

78

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Wind Tunnel Data

North

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Wind Tunnel Data

North

80

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Wind Tunnel Data

North

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Wind Tunnel Data

North

82

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Wind Tunnel Data

North

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Wind Tunnel Data

North

84

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Wind Tunnel Data

North

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Wind Tunnel Data

North

86

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Wind Tunnel Data

North

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Wind Tunnel Data

North

88

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Wind Tunnel Data

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Lift Coefficients All directions

Wind Tunnel Data

North

90

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Prescriptive Solar PV Wind Loads

� Convert data into a

prescriptive procedureBoundary Layer Wind Tunnel Laboratory

91


� Procedure needs to consider:

� Geometric Limitations of PV panels

� Roof Zoning


� Effect of Building Size (height & width)

� Panel Tilt Angle

� Array edge effects

� Panel Length

� Parapets

Prescriptive Solar PV Wind Loads

92

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Geometric Limitations of PV panels

� Based on most common

application and supported by

data

� Steeper, taller, longer

increases loads

93


Roof Zoning

� Roof zoning for open elements on roof

different than enclosed C&C elements

Components & Cladding Solar PV Arrays

94

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peak pressure on roof

peak pressure on solar panels in NE corner

� Snapshot image of vortex

Roof Zoning

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� Defined roof zones similar to ASCE 7

� Clarified steps, angled corners, reentrant corners

Roof Zoning

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Effective Wind Area

� GCn values are a function of effective wind area, similar to

ASCE 7 Wind Figures

Wind tunnel test data for solar PV ASCE 7-05 Figure 6-11B C&C

97


Effect of Building Size� Strength of vortex and resulting wind load increases with

size of building

� Kz does not account for this, it addresses gradient velocity

above ground

� SEAOC Method can apply > 60 ft

Height 15 ft 30 ft 60 ft

ASCE 7 C&CPrediction

Conservative Target Unconservative

SEAOC Solar PVGoal

Target entire range

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999 999 999 999 999 999 999 999 999 999 999 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 ### ### ### ### ### ### ### ### ### ### 999

999 999 999 999 999 999 999 999 999 999 999 999

Effect of Building Size

2H x 2H Building 6H x 6H Building

� Wind tunnel data to illustrate

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99



An = Normalized Wind Area

� How to address effect of building size?

An=��

�� ,��

�

Height 15 ft 30 ft 60 ft

A (area to component) 10 sf 10 sf 10 sf

An 44 11 2.8

Result on wind load decrease No change increase

A = Effective Wind Area

100

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� Illustrate on Solar PV GCrn curve

� No plateau

2.8

441

1

GCrn = 1.4

GCrn = 1.1

GCrn = 0.9

ASCE 7 C&C

101


Panel Tilt Angle

� Similar to open structures, wind pressure

increases as tilt angle increases

Tilt Angle

GCrn

5º 15º 35º0º

Interpolate GCrn 15º-35ºGCrn 0º-5º

102

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Panel Tilt Angle

� Tilt angle address through two GCrn Figures

� Uses normalized wind area, no flat plateau

� Values are for sheltered panels

Interpolate

103


Array Edge Effects

104

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Array Edge Effects

North

105


Array Edge Effects

5 panel x 4 row array

North

North edge factor (En) <=2

South, East, West

edge factor (Es,e,w)

<=1.5

� Apply factor to increase wind load on edges

of arrays and panels exposed from any side

Last 5 ft of row

received East and

West edge factor

106

54




Array Edge Effects

� Edge Factor:

� If spacing between rows gets large, then

all panels in the array will get an edge factor >1

� Gaps in the middle of an array for mechanical units,

skylights, etc will require all edges around gap to get an

edge factor >1

� Method developed requires each panel to have an edge

factor calculated in 4 principle axis directions (N,S,E,W)

and highest one used to design panel supports

� Edge factor becomes smaller close to building edge

107


Array Edge Effects

108

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Array Edge Effects

Evaluate toward adjacent panel

or building edge, whichever is

closer:

Adjacent panel:

dx= distance to adjacent panel

hc= min (h1, 1ft)+lpsin(ω)

(hc≈height of panel above roof)

Building edge:

dx= distance to building edge

hc=0.1*apv

(apv≈height of building roof)

109


Array Edge Effects

hc=2 ft

dN= 10 ft

north south

ground

roof

wind

Determine EN

Example:

dN/hc=5,

then EN=1.5

Observations:

-If dN<4 ft, EN=1

-If dN>16 ft, EN=2

-Keep space between

rows less than 2*hc

Shear Layer -

Reattachment

110

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Array Edge Effects

dN= 10 ft

north south

ground

roof

windDetermine EN

Example:

hc=0.1*apv=3 ft

dN/hc=3.3,

then EN=1.2

Observations:

-If dN<6 ft, EN=1

-If dN>24 ft, EN=2

-Keep space between

edge of building less

than 2*hc≈0.2*h

h= 30 ft(h≈apv)

Shear Layer - Reattachment

111


Other Effects

� Panel chord length factor (γc):

� The longer the panel, the higher the

wind pressure

� Panels <= 4’-4”, γc=0.8

� Panels 6’-8”, γc=1.0, interpolate betw.

� Parapet height factor (γp):

� The taller the parapet, the higher the wind

pressure in some areas

� Parapets <= 4’-0”, γp=1.0

� Parapets > 4’-0”, γp=0.25 hpt, need not exceed 1.3

112

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Final SEAOC Solar PV Figure

Roof Zoning Geometric

Limitations

-Panel Tilt Angle

-Effective Wind

Area & Building

Size Effects

Array Edge

Effects

113


Final SEAOC Solar PV Figure

Array Edge

Effects

Building Size

Effects

Panel Length

EffectsParapet

Effects

114

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BREAK!



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116

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Strategies to Avoid High Wind Loads

� Place panels > 2 * building height (h) from

building edges

� Avoid isolated panels, need sheltering

� If within 2h of building edge, place close to

building edge below shear layer, best if less

than 0.2*building height from edge

� Keep gap between rows small and aisles

between arrays as small as possible, best if

less 2*height of panel above roof (to highest

point of panel)117


Strategies to Avoid High Wind Loads

118

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EFFECTIVE WIND AREA

119


Effective Wind Area

� Wind flowing over roof is turbulent and gusty

� Wind pressure is not uniform and varies with

time at any one location

� Members and connections with small tributary

areas are subject to the instantaneous high

peak pressures

� Members and connections with large tributary

areas are subject to lower pressures because

the pressures over the entire area do not peak

at the same time.120

61




Effective Wind Area

SEAW/ATC-60 Figure 9-7

Peak pressures to design

roof sheathing attachment

Lower pressures to design

roof purlin (averaging effect)

121


Effective Wind Area

� EFFECTIVE WIND AREA, A for solar arrays: The area used to determine GCrnper Figure 29.9-1 is equal to the tributary area for the structural element being considered, except that the width of the effective wind area need not be less than one-third its length. For a fastener attaching solar modules, the effective wind area shall not be greater than the area tributary to the individual fastener.

122

62




Effective Wind Area


Example

Panel to rack attachment

Roof attachment

Rack beam

Plan View of PV panels

123


Effective Wind Area


Panel to rack attachment:

Effective wind area = ¼ panel area

(i.e. tributary area)

124

63




Effective Wind Area


Rack beam effective wind area:

Width of effective wind area is larger of:

• Tributary width

• 1/3 span length between supports ( )

Span length

125


Effective Wind Area


Roof attachment effective wind area:

Width of effective wind area is larger of:

• Tributary width

• 1/3 span length tributary to supports ( )

Span length tributary

to support

126

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Effective Wind Area

� If solar array support system has adequate

strength and interconnectedness to span

across a support or ballast point that is subject

to yielding or uplift, the tributary area (and

effective wind area) can be correspondingly

increased, provided that strengths are not

governed by brittle failure and that the

deformation of the array is evaluated and does

not result in adverse performance.

127


Effective Wind Area


If justified, larger effective area could be

used, see example in Appendix

� For example, say roof attachment spacing reduced, but

rack beam had adequate strength and interconnectedness

to span across multiple supports

128

65




Effective Wind Area


If rack robust enough, effective area for

sliding could use the entire array area.

� For sliding, if the racking system had adequate strength and

interconnectedness to engage larger areas, then that larger

effective wind area may be used

129


WIND TUNNEL PROCEDURE

130

66





ASCE 7

Wind Tunnel Procedure (WTP)

What’s an appropriate wind tunnel study?

ASCE 7 WTP is written for specific building modeling, not generalized buildings with solar panels.

Should the WTP be peer reviewed?

Is there a minimum wind load?

Does building need to be modeled?

Roof zoning?

Etc…

131



� What are acceptable testing methods?

132

67





133


� Wind tunnel model requirements

� Promote consistency

� Requirements for developing generalized wind loads

� Must comply with ASCE 49-12 “Wind Tunnel Testing

for Buildings and Other Structures”

� Boundary layer wind tunnel


134

68




� Wind tunnel model requirements

� Model array on generic building

� Roof zones

� Effective wind area

� Panel geometry (size)

� Panel tilt angle

� Row spacing

� Height above roof

� Roof shape (flat, barrel, pitched)

� Some interpolation allowed between multiple tests


135


Boundary Layer Wind Tunnel Laboratory


136

69




� For solar PV systems that meet the limitations

and geometry requirements of the SEAOC

Solar PV Figure, then:� Minimum is 50% of values in SEAOC Solar PV Figure

� Minimum of 10 psf in ASCE 7-05 not applicable (16 psf in

ASCE 7-10)

� Lower values allowed if qualified peer review

� For other systems:� Minimums in ASCE 7 should apply

� Lower values allowed if qualified peer review

Minimum Design Wind Loads

137


� Independent peer review

� Knowledgeable reviewer experienced in

performing wind tunnel studies on buildings in

atmospheric boundary layers.

� Review report, data, modeling, wind loads,

GCrn values, etc

� Prepare a report

� A peer reviewed wind tunnel study can be

used on multiple projects, unless scope of

applicability changes

Peer Review Requirements

138

70





� Computation Fluid Dynamics is not recognized

by ASCE 7

139


EXAMPLE SOLAR PV PROBLEM

140

71




Example Solar PV Problem

� Example Problem in Appendix

� Aid in interpretation and application of method

141


� 9 locations selected to provide sample

calculations for (8 attached, 1 ballasted)


142

72




� Procedure outlined in Section 3.2.1 of Report


143


� Step 5 – Determine Roof Zones


144

73




� Step 10 – Determine Edge Factors


E=2

E=1

145



� Step 13 – Determine Pressure

p=96 psf (SD)

=56 psf (ASD)

p=30 psf (SD)

=17 psf (ASD)

Pressures

shown for panel

connections,

would be lower

for roof

connections

146

74




� Formulas for GCrn curves provided


147



� Ballasted system example for Location 9

� Illustrates need for wind tunnel tested aerodynamic

systems to make feasible

148

75




SOLAR PV CODE DEVELOPMENT

149


SEAOC Solar PV Reports into Code

Current Efforts• SEAOC Solar

PV Systems Committee

• Solar ABC• Technical

Papers• Wind Tunnel

Studies• ASCE 49

ASCE 7(2016)

IBC(2018)

2013 CBC Amendments, 2012 IBC, DSA

IR 16-8

What’s next?

150

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DSA IR 16-8

� Updated in October 2012 to incorporate SEAOC PV

reports

� Available at: www.dgs.ca.gov/dsa

151


DSA IR 16-8

� DSA IR 16-8 addresses:

� Dead load – Check roof, keep mass increase below 10%

� Live load – No need to include where covered by panels < 24” or

signs

� Wind – SEAOC PV paper, Wind tunnel requirements, peer review

� Seismic – ASCE 7 loading, unrestrained systems per SEAOC PV

paper

� Load combinations – Apply load combo’s when checking uplift

� Rack design – ICC AC 428

� PV Installations on Standing Seam Metal Roofs

� BIPV systems – ICC AC 365

� Fire Life Safety requirements

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2013 CBC

� 2013 CBC Amendment to 2012 IBC

Section 1509.7

� Effective wind area should NOT be based

on effective wind area of a single unit frame

� DSA and HCD co-adopt Exception

153


2013 CBC

� 2013 CBC Section 1613.5 – amendment

to modify ASCE 7-10 Section 13.4 to

allow unrestrained solar arrays.

Next Slide

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2013 CBC

� 2013 CBC Section 1613.5 (continued).

SEAOC Seismic PV Paper indicates how to do this

155


� SEAOC Solar PV Reports will be updated

annually +- as we receive feedback

� Spreadsheet developed to automate process

Future Updates to SEAOC PV Reports

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Acknowledgements

157


THANK [email protected]

80







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Thank You!!

For more information…www.skghoshassociates.com

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Wind Loads on PV Arrays - S. K. Ghosh Associates

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