What is the relationship between the installation height of solar street lights, the distance between light poles and the width of the road surface

Designing a solar street light system is more than simply mounting lamps on poles. There's a close, professional relationship between mounting height, pole spacing, and road width, directly determining lighting performance, project costs, and driving safety. A rational layout is key to ensuring maximum solar street light efficiency.

Mounting Height and Lighting Performance
Mounting height is the primary factor affecting light coverage and uniformity. Generally, higher mounting heights increase the area illuminated on the road surface. This means taller poles can cover a wider road surface, reducing the number of lamps required.

However, increasing mounting height isn't without limits. As height increases, the light attenuation of LED light sources increases, resulting in a corresponding decrease in the illumination reaching the ground. Therefore, lamps with higher lumen efficiency are needed to compensate for this loss in illumination. In actual projects, the optimal mounting height is determined by the road width and the desired average illumination level. For example, for wider main roads, poles 8-12 meters or even higher are typically selected to ensure adequate illumination coverage and uniformity. For rural roads or residential roads, a height of 5-6 meters is sufficient.

Light Pole Spacing and Illumination Uniformity
Light pole spacing directly determines the uniformity of road lighting. If spacing is too large, the overlap between adjacent luminaires will decrease, resulting in an uneven "zebra crossing effect" on the road surface, impacting the comfort and safety of drivers and pedestrians.
To achieve optimal lighting uniformity, a recommended ratio between pole spacing and mounting height is typically between 2.5 and 4, meaning the pole spacing should be 2.5 to 4 times the mounting height. For example, for a streetlight mounted at an 8-meter height, the ideal spacing is typically between 20 and 32 meters. During design, this ratio requires fine-tuning based on the specific luminaire's light distribution curve (e.g., batwing or rectangular spot). Professional lighting design software simulations can accurately calculate the optimal spacing to ensure that the minimum illumination on the road surface meets national or industry standards.

Linking Road Width and Design Parameters
Road width is the fundamental parameter for determining mounting height and pole spacing. The goal of all lighting design is to provide uniform light coverage across the entire road surface. For narrow roads (e.g., 4-6 meters), a single-sided lighting layout is typically used. In this case, the luminaires are typically mounted at a lower height (e.g., 6 meters), and the pole spacing can be increased to save costs.
For medium-width roads (e.g., 8-12 meters), single-sided or double-sided staggered lighting can be used. If single-sided lighting is used, luminaires with a wider light distribution angle should be selected, and the mounting height should be increased to cover the entire road surface. Double-sided staggered lighting can effectively improve lighting uniformity, but the number of poles required will be increased.
For wider main roads (e.g., over 15 meters), double-sided symmetrical or double-sided staggered lighting is usually necessary. In this case, higher pole heights (e.g., over 12 meters) are required, and more specialized luminaire light distribution designs should be employed to ensure adequate illumination at both the center and edges of the road surface.

Comprehensive Consideration of the Three Interrelated Parameters
In actual project design, these three parameters do not exist independently; rather, they constrain and influence each other. A scientific solar street light design requires comprehensive consideration of the following:
Determine road width and lighting requirements: This is the starting point for all designs. Roads of different grades have different requirements for average illumination and uniformity.
Choose the appropriate mounting height: Preliminarily determine the mounting height based on the road width and the light distribution characteristics of the lamps.
Calculate the optimal pole spacing: Based on the mounting height and the light distribution characteristics of the lamps, use lighting simulation software to determine the pole spacing that achieves optimal uniformity.
Evaluate project costs: Taller poles and smaller spacing generally result in higher project costs. It is important to find the optimal cost-effective solution while meeting lighting requirements.