Guide to LED Street Lights/ LED solar street lights
The purpose of solar street lights is to illuminate the surroundings – including the road and adjacent areas in a manner that human beings using the area can adequately perceive the area and its surroundings. Street light lamp are thus a vital instrument in ensuring safety from accidents and unsocial elements. Indeed in several studies LED light for street have been linked with feelings of safety and reduction in accidents.
The Perception of Lights and the Ideal Solar Street Light
Light is perceived by the retina of the eye. The cone cells in the eye work in bright light and register color while the rod cells work in dim light and register the presence of light. The retina in turn is protected from excessive light by the pupil. The pupil alters it size in response to changing light levels. Thus, the pupil is wide open in dim light and becomes very small in bright light – thus controlling the amount of light entering the eye and protecting the retina from excessive light that may damage the light sensitive cells.
The pupilary muscles are the most relaxed in dim light and are most tightly contracted in bright light. Thus these muscles fatigue quickly when there is excessive light.
For these reason–
Street light solar powered should produce good quality light to ensure good contrast between objects and good color discrimination.
Path light solar should provide constant illumination levels. Fluctuating lights or changing illumination levels will cause the pupilary muscles to tire quickly.
Several factors are instrumental in determining the quality of visual perception and the performance of solar powered light outdoor .
Light output by the lamp
Light reflection from the road and other surfaces
Color rendering ability
Mesopic vision as determined by the S/ P ratio of light
Ratio between maximum lumens, average lumens and minimum lumens
Uniform distribution of light
Cut off angle of the fixture
For solar light on pole - Height of the mounting pole ,Optimum pole height is important for the correct lighting density. As the height of the mounting pole increases the footprint of the light increases but light density decreases.
Luminosity of Street Lights / solar path light
Luminosity is the light output from a lamp. A small lamp producing a lot of light results in greater brightness and consequent glare when looked at directly. LED Street Lighting Systems on the other hand consist of multiple light producing points thus reducing glare.
Light footprint of different types of Luminaries( solar walk way lights )
Some of the basic types of luminaries according to IES’s classification and their typical position along roads is shown in the figure above. Thus while Type 5 are suitable for installation for a 360 degree illumination footprint, Type 1 is most suitable for installation along a road median.