Consideration of the standard lux levels for solar street lights: How do we determine the required lux level?

Consideration of the standard lux levels for solar street lights: How do we determine the required lux level?

Light Measurement for Solar Street Lighting Systems

In the context of solar street lighting systems, the assessment of brightness relies on two key metrics: Lux and Lumens. Lux and lumens serve as units of measurement for brightness, facilitating the quantification of the illumination output and the brightness of light impacting a specific surface.

Lumens represent light output, while lux (lx) measures luminous flux per unit area.

Relationship between lumens and lux：

One lux is equal to one lumen per square meter (lm/m2).

In the following discourse, we will examine the Lux standards pertaining to street lighting and elucidate their significance. Should you seek to enhance your understanding of lumens, we recommend perusing the article titled "Understanding Watts and Lumens: How to Choose the Right Brightness Light Fixture for Your Project."

WHAT IS LUX AND WHY IS IT IMPORTANT?

Lux represents a measurement of the light flux that reaches a given surface. This unit serves as the international standard for photometry, the science of measuring light intensity. Lux is commonly employed to articulate light brightness and illumination levels across various lighting applications, including household, commercial, automotive, and street lighting systems.

WHY LUX LEVEL MAKE SENSE THAN LUMEN

Lumens quantify the luminous flux emitted by a singular light source. The method for calculating lumens involves multiplying the wattage by the rated lumens per watt of the light source.

Lux denotes the illuminance on a surface and is indicative of the brightness of light after it has traversed a specific distance.

In the context of solar street lights, Lux levels serve as an effective means of gauging brightness. While illuminance measurement can be readily conducted using an illuminance meter, luminance measurement necessitates specialized equipment and is comparatively more complex.

For instance, a solar street light bulb producing 1000 lumens will exhibit varying brightness levels when positioned 10 meters apart. Consequently, the alteration of the bulb's placement results in differing brightness levels under distinct Lux conditions. Lumens gauge the light output of the bulb, while Lux measures the distance traversed by light.

DIFFERENT ROAD SOLAR STREET LIGHTING LUX LEVELS

According to standards specified in some countries’ government documents, we provide the following recommendations as a reference:

HIGHWAY LIGHTING LUX LEVELS

For first-class and second-class highways, the minimum average illuminance maintenance values are specified as 20 lx (low standard) and 30 lx (high standard), with a minimum uniformity value of 0.4.

Third-class highways are required to maintain a minimum average illuminance of 15 lx (low standard) and 20 lx (high standard) with a uniformity threshold of 0.4.

Fourth-class roads must meet average illuminance levels of 10 lx (low standard) and 15 lx (high standard) with a uniformity level of 0.3.

These illuminance specifications pertain exclusively to asphalt roads; for concrete roads, a reduction of up to 30% in illuminance requirements is allowable.

The determination of highway lighting levels should be based on the lighting standards of adjacent urban roads, the highway traffic control system, and road partitioning facilities.

High standard illuminance values are warranted in the following scenarios:

1. connection to urban roads with high-grade lighting standards;

2. poor visibility conditions;

3. inadequate highway traffic control systems and road partitioning facilities.

Conversely, low standard values are to be employed for highway lighting when connected to urban roads with low-grade lighting standards, under conditions of good visibility, and when the highway traffic control systems and road partitioning facilities are adequate.