Wind Resistance Design for Solar Street Lights

1. Wind Resistance Design of Solar Panel Brackets

1.1 Tilt Angle Design

To maximize solar radiation received by the solar panels throughout the year, it is important to choose an optimal tilt angle. This angle is generally related to the local latitude but can be adjusted based on specific needs.

Formulas:

• θ = Latitude + 5° (suitable for northern regions)
• θ = Latitude - 5° (suitable for southern regions)

For example, the latitude of Guangzhou is about 23°, making the optimal tilt angle 18°. In northern areas such as Jinan, with a latitude of approximately 36.6°, the optimal tilt angle would be 41.6°.

1.2 Wind Resistance Design

The solar panel bracket must withstand local wind speeds without sustaining damage, considering the connection between the bracket and the lamp post.

Formulas:

• F = 1.3 × 730 N = 949 N (considering a safety factor of 1.3)
• M = F × 1.545 m = 949 N × 1.545 m = 1466 N·m

Where F is the basic load on the solar panel, and M is the moment of wind load on the failure surface of the lamp post.

Connection Method: Use bolt rods to securely connect the solar panel bracket to the lamp post.

2. Wind Resistance Design of Lamp Posts

2.1 Lamp Post and Foundation

The wind resistance design of lamp posts and foundations is affected by factors such as panel height, area, tilt angle, lamp post structure, and local maximum wind speeds.

Formulas:

• P = [H + (D + t) / tan(θ)] sin(θ)
• M = F × P
• σ = M / W

Where H is the height of the lamp post, D is the outer diameter at the base, t is the weld width, θ is the solar panel tilt angle, F is the wind load, P is the distance from the wind load application point to the base of the lamp post, M is the moment due to wind load on the failure surface of the lamp post, W is the resisting moment at the failure surface, and σ is the stress.

Specific Parameters:

• Height of lamp post \(H = 5 \text{ m}\)
• Outer diameter at base \(D = 168 \text{ mm}\)
• Weld width \(t = 4 \text{ mm}\)
• Solar panel tilt angle \(θ = 16^\circ\)
• Wind load \(F = 949 \text{ N}\)

Calculations:

• P = [5000 + (168 + 6) / tan(16°)] sin(16°) = 1545 mm = 1.545 m
• M = 949 N × 1.545 m = 1466 N·m
• W = π(3rD + 3rd + d)
• r = 84 mm, d = 4 mm
• W = π(3 × 84 × 4 + 3 × 84 × 4 + 4) = 88.768 × 10^{-3} m^3
• σ = 1466 N·m / (88.768 × 10^{-3} m^3) = 16.5 MPa

Material Requirements: The flexural strength of Q235 steel is 215 MPa, thus the selected weld width meets the requirement.

3. Application Recommendations for Various Scenarios

3.1 Coastal Areas in Europe (e.g., Southern UK)

• Maximum Wind Speed: Should withstand at least a level 10 gale.
• Design Recommendations:
  • Choose high-strength lamp post materials, such as Q235 steel.
  • Ensure secure connections between the lamp post and foundation, with weld width not less than 4 mm.
  • The solar panel bracket should withstand wind pressures of 2500 Pa.
  • Consider the rainy climate of coastal regions; ensure the panel system has good waterproofing.

3.2 Plain Areas in Europe (e.g., Central France)

• Maximum Wind Speed: Generally level 8 winds.
• Design Recommendations:
  • Select appropriate lamp post height and diameter for improved stability.
  • Increase the weld width at the base to enhance wind resistance.
  • Adjust the tilt angle of the solar panel bracket according to local latitude for optimal light reception.
  • Although wind speeds are lower, consider lightning protection measures for stormy weather.

3.3 Inland Mountain Areas in Europe (e.g., Swiss Alps)

• Maximum Wind Speed: According to local meteorological data, may reach level 12 winds.
• Design Recommendations:
  • Choose sturdy materials for the lamp post and increase foundation depth.
  • Ensure the solar panel bracket can withstand significant wind pressure.
  • Due to complex terrain, adjust lamp post height and layout to avoid shading.
  • Ensure the panel system has good low-temperature resistance for cold mountainous climates.

3.4 Plain Areas in the U.S. (e.g., Kansas)

• Maximum Wind Speed: Generally level 8 winds.
• Design Recommendations:
  • Choose high-efficiency solar panels to reduce footprint.
  • Determine lamp post height based on road width and lighting requirements.
  • Equip controllers with multiple protections against reverse charging, overcharging, over-discharging, short circuits, and reverse polarity.
  • Increase lamp post rigidity and stability due to higher wind speeds in plains.

3.5 Mountain Areas in the U.S. (e.g., Colorado)

• Maximum Wind Speed: May reach level 12 winds based on local meteorological data.
• Design Recommendations:
  • Use high-strength lamp post materials, such as Q235 steel.
  • Ensure firm connections between the lamp post and foundation, with weld widths no less than 6 mm.
  • The solar panel bracket should withstand wind pressures of 3000 Pa.
  • Ensure good low-temperature performance in panels for cold weather resistance.
  • Given the complex terrain, adjust lamp post height and layout as necessary to avoid shading.

3.6 Inland Areas of Australia (e.g., Queensland)

• Maximum Wind Speed: Generally level 6 winds.
• Design Recommendations:
  • Select lower-powered solar panels to reduce costs.
  • Consider slightly reducing lamp post height to minimize wind load.
  • Ensure controllers have light and time control functions to extend lamp operation time.
  • The solar panel system should have good high-temperature resistance to cope with the hot inland climate.

4. Conclusion

The wind resistance design of solar street lights requires comprehensive consideration of geographical location, weather conditions, material selection, and structural design. By following the formulas and application suggestions outlined above, engineers can design systems that ensure stable operation under various adverse weather conditions. Specific design parameters and material choices should be adjusted based on local requirements to achieve optimal wind resistance performance.