Solar Powered Street Lights, the future of
street lighting
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Solar powered street lights are a very good example on what can be done with solar energy.
A growing number of solar street lighting projects are running in Africa, Asia and the Middle East. Some
European and US cities are currently running pilot projects.
The concept is straightforward and we shall see more countries migrating this way. well
chosen, solar street lights are cost-effective, cost-saving and reliable.
NUTS & BOLTS

Solar Panel
Its task is to convert the sun's energy into electricity. Different sizes and power outputs
are available. They have to be carefully chosen for the desired application. Solar panels should be able to
withhold and deliver in extreme weather conditions. Some are even designed unbreakable (vandal proof), others will
work well in overcast weather. A 20 Year Warranty on good solar panels is not unusual.
Solar Controller
The basic circuitry on most solar powered street lights consists essentially of an automatic
battery charger fed by the solar panel and a lighting controller automated for dusk to dawn operation. Automatic
lighting can be triggered by a photocell or a timer. On some models a special feature dims the light at a given
time, thus allowing a longer operation time
Battery
Maintenance-free batteries are generally used on solar street lights. In addition to
providing energy for dusk to dawn operation, they must also be able to supply few days of backup power in case of
bad weather or charger failure.
Lamps
The choice of lamps to use in solar powered street lights is dictated by the kind of
application you're after:
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LEDs (Light Emitting Diodes) also known as SSL (solid-state lighting) have a good
color rendition. A cluster of extra or ultra bright LEDs forms the lamp. LEDs consume a
fraction of the energy of comparable lighting and have a very long life span. Solar LED street lights are an emerging and promising
application for LED technology.
CF (Compact Fluorescent) lamps produce a white light and are used in places where
color rendering is desired.
HID (High Intensity Discharge) lamps, mainly LPS and MH:
LPS (Low Pressure Sodium) lamps generate a monochromatic yellow-orange light and
are used when color rendering is not an issue. They have a lifespan of up to 18,000 hours
MH (Metal Halide) lamps produce a clean white light and are perfect for
applications where color rendering is essential
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An overview on solar street
lights
How solar street lights work
OK, solar powered street lights are full of electronics...
The solar panel converts the sun's energy to dc electricity.
Voltage is then regulated to a specific value by an electronic circuit to charge the battery. A solar controller
protects the battery from too low and over charge.
Now for the lighting. Contrary to LEDs, HID and CF lamps require a high voltage, particular current, and frequency
to work. It is the ballast's task to feed the lamp properly.
We now need to control the lamp. To do so, a timer or photocell does the job of switching the light from dusk to
dawn. On some advanced solar powered street lights models, intensity and color can even be adjusted.
More info on solar street lighting
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