Urban roads Solar street lighting design guidelines – Urban roads Solar street lights

The following is the “Urban Road Solar Lighting Design Guide” based on the International Lighting Standards (CIE/CJJ):

1. Brightness and Light Efficiency Design

1. Illuminance Standards (Lux)
   • Expressways/Main Roads: Maintain an average illuminance of 25-30 lux (asphalt pavement), reduce by 20%-30% for cement pavement; initial values need to be increased by 30%-50%.
   • Secondary Roads: Maintain 15-20 lux with uniformity ≥0.4.
   • Branch Roads/Sidewalks: Maintain 5-10 lux with uniformity ≥0.3.
   • Bicycle Lanes: Take 1/2 of the illuminance of the adjacent motor lanes.
2. Lumens and Light Efficiency
   • LED light source efficiency ≥150 lm/W; total luminaire efficiency ≥120 lm/W.
   • Calculation formula: Total lumen requirement = target illuminance (lux) × area (m²) / utilization factor (0.6-0.8).

2. Color Temperature and Color Rendering Index

1. Color Temperature Selection
   • Traffic Roads: 4000-7000K (high color temperature enhances alertness).
   • Residential Roads: 3000-4000K (low color temperature creates a sense of comfort).
   • Landscape Areas: 2700-3000K (warm white light matches the environment).
2. Color Rendering Index
   LED light source Ra ≥80 (CJJ45-2006 requires Ra ≥70), ensuring clear recognition of object colors.

3. Lamp Post and Fixture Design

1. Height and Spacing
   

   Road Type	Pole Height (m)	Spacing (m)	Lighting Arrangement
   Expressway/Main Road	10-12	30-35	Symmetrical layout on both sides
   Secondary Road	8-10	25-30	Alternating layout on both sides
   Branch Road/Sidewalk	6-8	20-25	Single side or alternating layout

2. Materials and Structure
   • Material: Hot-dip galvanized steel (corrosion life ≥25 years) or aluminum alloy (lightweight).
   • Wind resistance level: ≥Level 12, seismic intensity ≥Grade 8.
   • Pole wall thickness: ≥4mm (height ≤10m), ≥6mm (height >10m).

4. Solar System Design

1. Continuous Lighting Guarantee
   • Battery life during rainy days ≥3-5 days (battery capacity = average daily power consumption × number of days × 1.2 redundancy factor).
   • Photovoltaic panel power: Designed for an average daily sunlight of 4 hours, power ≥ system daily consumption/4h.
2. Automatic Control Optimization
   • Smart Dimming: Adjust brightness by time period (e.g., reduce to 50% power after 22:00).
   • Sensor Control: Microwave/infrared sensing (energy-saving mode activated if traffic flow <10 vehicles/hour).
   • Remote Monitoring: Integrated LoRa/NB-IoT module for real-time system status monitoring.

5. Cost and Return on Investment (ROI)

1. Initial Cost
   

   Item	Unit Price Range (CNY/set)
   Solar LED Street Light	4500-8000 (approximately 662-1176 USD)
   Smart Control System	500-1200
   Installation and Construction	1000-2000

2. Operational Cost Comparison
   • Traditional Street Lights: Electricity cost 0.8 CNY/kWh, annual maintenance cost about 15%.
   • Solar Street Lights: Annual maintenance cost ≤5%, no grid electricity cost.
3. ROI Calculation
   • Payback period: 5-8 years (based on 10 hours of lighting per day).
   • Lifetime savings: Total cost savings ≥200% over 25 years (compared to traditional lighting).

6. International Standards Reference

• CIE 115-2010: Road lighting brightness and uniformity specifications.
• CJJ45-2015: China urban road lighting design standards.
• IEC 62776: Performance and safety requirements for LED street lights.

(Note: Specific parameters should be adjusted based on local latitude, climate data, and road grade; it is recommended to use Dialux or AGi32 software for optical simulation verification.)