What ASCE 7 section covers solar panel wind loads?

ASCE 7-16 and ASCE 7-22 Chapter 29 covers solar panel wind loads. Section 29.4.3 addresses rooftop panels on low-slope roofs (less than 7 degrees), Section 29.4.4 covers tilted panels on steeper roofs, and ASCE 7-22 added Section 29.4.5 specifically for ground-mounted solar arrays.

What is the design wind pressure formula for solar panels?

The design wind pressure for rooftop solar panels is p = qh × GCrn, where qh is the velocity pressure at mean roof height and GCrn is the net pressure coefficient. GCrn is calculated as GCrn = γp × γc × γE × GCrn,nom, incorporating parapet, chord length, and exposure factors.

What is the difference between ASCE 7-16 and ASCE 7-22 for solar panels?

ASCE 7-22 added Section 29.4.5 for ground-mounted solar arrays, which was not in ASCE 7-16. It also incorporated the directionality factor (Kd) into all force and pressure calculations, refined roof zone designations, and added requirements that solar panels cannot be part of the structural load path unless specifically tested.

What is the edge factor (γE) for solar panels?

The edge factor γE equals 1.5 for uplift loads on panels that are exposed and within a distance of 1.5×Lp from the end of a row at an exposed edge of an array. γE equals 1.0 elsewhere and for all downward loads. This accounts for increased wind pressures at array edges.

How do roof zones affect solar panel wind loads?

Solar panels in Zone 3 (corners) experience the highest wind pressures, followed by Zone 2 (edges), and Zone 1 (interior field). Panel location relative to roof edges determines the applicable GCrn,nom coefficient from Figure 29.4-7, which directly affects design wind pressure.

Solar Panel Wind Load Guide | ASCE 7-16 & 7-22

☀ Introduction to Solar Panel Wind Loads

Solar photovoltaic (PV) systems must be designed to resist wind loads per ASCE 7 (Minimum Design Loads and Associated Criteria for Buildings and Other Structures). With the rapid growth of solar installations, ASCE 7-16 introduced dedicated provisions for solar panels, and ASCE 7-22 expanded these requirements further.

This guide covers wind load calculations for both rooftop-mounted PV systems and ground-mounted solar arrays, explaining the differences between ASCE 7-16 and ASCE 7-22, the applicable sections, and step-by-step calculation procedures.

ⓘ Why Solar Panel Wind Loads Matter

Solar panels create unique aerodynamic conditions on rooftops. They can experience significant uplift forces, and their mounting systems must resist both uplift and sliding. Improper design can lead to panel damage, roof damage, or even panels becoming windborne debris during high-wind events.

📖 ASCE 7 Sections for Solar Panels

Both ASCE 7-16 and ASCE 7-22 address solar panel wind loads in Chapter 29 (Wind Loads on Building Appurtenances and Other Structures). The key sections are:

Section	Application	ASCE 7-16	ASCE 7-22
29.4.3	Rooftop panels on flat or low-slope roofs (< 7°)	✔	✔
29.4.4	Rooftop panels on steeper roofs (≥ 7°)	✔	✔
29.4.5	Ground-mounted solar arrays (fixed-tilt)	✘	✔ (NEW)

✔ ASCE 7-22 Adoption Status

ASCE 7-22 is referenced in the 2024 International Building Code (IBC) and International Residential Code (IRC). Florida has already adopted ASCE 7-22, and other states are expected to follow as they adopt the 2024 codes.

🔢 Design Wind Pressure Formula

The design wind pressure for rooftop solar panels per ASCE 7 is calculated using:

p = q_h × GC_rn

p = design wind pressure (psf)
q_h = velocity pressure at mean roof height (psf)
GC_rn = net pressure coefficient for solar panels

The net pressure coefficient GC_rn is the product of several gamma (γ) factors:

GC_rn = γ_p × γ_c × γ_E × GC_rn,nom

γ_p = parapet factor
γ_c = chord length (configuration) factor
γ_E = edge/exposure factor
GC_rn,nom = nominal net pressure coefficient from Figure 29.4-7

Gamma Factor Details

γ_p

Parapet Factor

γ_p = min(1.2, 0.9 + h_pt/h)

Where h_pt is parapet height and h is building height. For buildings without parapets, γ_p = 0.9

γ_c

Chord Length Factor

γ_c = max(0.6 + 0.06×L_p, 0.8)

Where L_p is the panel chord length (ft). Accounts for panel size effects.

γ_E

Edge Factor

γ_E = 1.5 for exposed panels within 1.5×L_p from array edge (uplift only)

γ_E = 1.0 elsewhere and for all downward loads

GC_rn,nom

Nominal Coefficient

From Figure 29.4-7 based on:

- Normalized wind area (A_n)
- Roof zone (1, 2, or 3)
- Panel tilt angle

🗺 Roof Zones for Solar Panels

Solar panel location on the roof determines which zone applies. Panels near edges and corners experience higher wind pressures than those in the interior field.

Zone 1 Interior Field

Panels located in the interior of the roof, away from edges. These experience the lowest wind pressures and have the lowest GC_rn,nom values.

Zone 2 Roof Edges

Panels located near roof edges (excluding corners). Wind accelerates over edges, creating moderate wind pressures higher than Zone 1.

Zone 3 Roof Corners

Panels located at roof corners experience the highest wind pressures due to wind vortex formation. Highest GC_rn,nom values apply.

⚠ Zone Boundaries per Figure 29.4-7

Zone boundaries are defined based on building height (h) and minimum building dimension. The edge zone width is typically calculated as 0.1 × min(building length, building width), but not less than 0.4h. Consult ASCE 7 Figure 29.4-7 for exact zone boundary definitions.

📐 Panel Tilt Angle Categories

The tilt angle (ω) of solar panels affects the applicable GC_rn,nom values. ASCE 7 provides coefficients for different tilt angle ranges:

Tilt Angle Range	Typical Application	Wind Effect
0° - 5°	Flush-mounted panels on flat roofs	Minimal uplift, acts similar to roof surface
5° - 15°	Low-tilt arrays, ballasted systems	Moderate uplift forces begin
15° - 35°	Typical tilted arrays for optimal solar gain	Significant uplift and sliding forces
> 35°	Steep-angle installations	High uplift, may need special analysis

The tilt angle is calculated as: ω = arctan[(h₂ - h₁) / L_p], where h₂ is the high edge height, h₁ is the low edge height, and L_p is the panel chord length.

📈 Normalized Wind Area

The normalized wind area (A_n) is used to determine GC_rn,nom from Figure 29.4-7:

A_n = (1000 / [max(L_b, 15)]²) × A

A = effective wind area of panel (L_p × W_p) in ft²
L_b = characteristic length = min(0.4 × √(h × W_L), h, W_s)
h = mean roof height
W_L = building width perpendicular to wind
W_s = building width parallel to wind

🏭 Exposed Panel Criteria

A panel is considered "exposed" (requiring γ_E = 1.5 for edge panels) when:

d₁ > 0.5 × h (setback from roof edge exceeds half the building height)

AND either:

Distance to adjacent array exceeds max(4 × h₂, 4 ft)
Distance to next panel in row exceeds max(4 × h₂, 4 ft)

ⓘ 24-Inch Height Threshold

Per ASCE 7-16 and 7-22, rooftop solar panel systems mounted 24 inches or less above a low-slope roof surface do not require live load modeling as a separate structure. This simplifies analysis for typical flush-mount installations.

🌏 ASCE 7-22: New Ground-Mount Provisions (Section 29.4.5)

ASCE 7-22 introduced Section 29.4.5 specifically for fixed-tilt ground-mounted solar arrays. This section did not exist in ASCE 7-16, which only addressed rooftop installations.

Key Features of Section 29.4.5

Dedicated methodology for ground-mount solar farms and utility-scale installations
Force coefficients specific to ground-mounted array configurations
Directionality factor (K_d) incorporated into all pressure calculations
Array spacing considerations for multi-row installations
Foundation design requirements for resisting overturning and sliding

✔ Ground-Mount vs. Rooftop

Ground-mounted systems typically experience different wind flow patterns than rooftop installations because they're not influenced by building aerodynamics. Section 29.4.5 accounts for these differences with specific force coefficients.

🔄 ASCE 7-16 vs. ASCE 7-22 Comparison

Feature	ASCE 7-16	ASCE 7-22
Rooftop Solar (29.4.3, 29.4.4)	✔ Included	✔ Included (refined)
Ground-Mount Solar (29.4.5)	✘ Not included	✔ NEW section
Directionality Factor (K_d)	Applied separately	Incorporated into calculations
Roof Zone Definitions	Standard zones	Simplified zone designations
Structural Load Path	General requirements	Panels cannot be load path unless tested
Tornado Loads (Chapter 32)	✘ Not included	✔ NEW (Risk Cat III/IV)

⚠ ASCE 7-22 Load Path Requirement

ASCE 7-22 specifies that "solar panels shall not be considered as part of the load path that resists the interconnection force unless panels have been evaluated or tested." This is an important change affecting structural design of PV mounting systems.

📝 Example Calculation

The following example demonstrates a solar panel wind load calculation for a rooftop installation:

Given Parameters:

Building location: Broken Arrow, Oklahoma
Design wind speed (V): 115 mph (Risk Category II)
Building height (h): 30 ft
Exposure Category: C
Panel dimensions: 65" × 39" (L_p × W_p)
Panel tilt: 20°
No parapet
Panels in Zone 3 (corner)

Step-by-Step Calculation:

Calculate velocity pressure (q_h): q_h = 32.28 psf (from ASCE 7 velocity pressure tables)
Determine γ_p: No parapet, so γ_p = 0.9
Calculate γ_c: L_p = 65"/12 = 5.42 ft
γ_c = max(0.6 + 0.06 × 5.42, 0.8) = max(0.925, 0.8) = 0.925
Determine γ_E: Assume interior panel (not at array edge), γ_E = 1.0
Calculate normalized wind area and find GC_rn,nom:
A_n = 78.24 ft² → GC_rn,nom = 1.607 (from Figure 29.4-7 for Zone 3, 15-35° tilt)
Calculate GC_rn:
GC_rn = 0.9 × 0.925 × 1.0 × 1.607 = 1.338
Calculate design wind pressure:
p = 32.28 × 1.338 = 43.2 psf

ⓘ Interpretation

The design wind pressure of 43.2 psf applies to both uplift and downward loading. The mounting system and attachments must be designed to resist these forces with appropriate safety factors per the applicable building code.

🛠 Design Considerations

Ballasted vs. Attached Systems

Rooftop solar systems are typically either ballasted (held in place by weight) or mechanically attached to the roof structure:

System Type	Advantages	Considerations
Ballasted	No roof penetrations, easier installation	Heavy weight on roof, limited to low-slope roofs, specific seismic requirements
Attached	Lower weight, suitable for all roof slopes	Roof penetrations required, waterproofing concerns

ⓘ Ballasted System Requirements

Per ASCE 7, ballasted systems must meet seven specific conditions for seismic compliance. The ballast weight must be sufficient to resist both uplift and sliding forces from wind loads.

Special Considerations for High-Wind Regions

Hurricane-prone regions: Higher wind speeds require increased ballast or stronger attachments
Windborne debris regions: Consider impact-resistant panel options
HVHZ (Florida): May require Florida Product Approval for PV systems
Tornado-prone regions: Risk Category III/IV buildings now require Chapter 32 tornado load analysis per ASCE 7-22

Calculate Your Solar Panel Wind Loads

Use our professional wind load calculator to determine design pressures for your solar installation per ASCE 7-16 or ASCE 7-22.

Get Solar Panel Calculator →

🔗 Resources and References

ASCE 7 Hazard Tool - Official tool for determining site-specific wind speeds
ASCE/SEI 7-22 Standard - Official ASCE 7-22 publication
ICC Digital Codes - International Building Code reference
NREL (National Renewable Energy Laboratory) - Solar energy research and data

ⓘ Professional Engineering Note

Solar panel wind load calculations should be performed or reviewed by a licensed Professional Engineer (PE). Local jurisdictions may require stamped calculations for building permit approval. Always verify requirements with your local building department.

Solar Panel Wind Load Calculations