Energy-saving solar street lighting with OSRAM LEDs
LED streetlighting installations with LEDs from OSRAM Opto Semiconductors can now be seen all over the world – from Johannesburg to Singapore, Budapest, Dubai, Bern and Heidelberg. And the interest in the new technology is big – other countries from all continents might follow.
The so-called STREETSUN from EPS Soltec is solar-powered and 44% more cost-effective than grid based streetlighting. This does not mean that brightness has to be compromised, however, as brilliant street lights equipped with OSRAM´s Golden Dragon LEDs amply demonstrate.
OSRAM Opto Semiconductors has developed two different special lenses for this application that direct the light accurately onto the street or onto squares and remove the need for secondary optics. The Golden Dragon OVAL LED has an oval beam shape and is adapted for lanes, cycle or foot paths whereas the Golden Dragon ARGUS LED radiates in all directions and is especially adapted for squares like parking sites.
Only twelve Golden Dragon LEDs per street light are sufficient to illuminate paths or squares from a height of 3.2 meters. They produce 82 lm each (at 350 mA) and are operated at 130 mA specifically for this application. The LED each consumes 0.35 W (1 W in standard applications). The oval lens of the Golden Dragon OVAL distributes the light down at an angle of 80° x 120°. This means that no light is lost sideways away from the path as is the case with the usual circular distribution of light from conventional street lights. The Golden Dragon ARGUS instead has an angle of radiation of 160° and the light is spread in all directions. Therefore it is primarily used for illumination of squares.
New is the possibility to assemble the head of the STREETSUN with a wall holder directly on buildings. Moreover, the time management which is available in the fall of 2008 allows to set the illumination period over night exactly. All variations are available, e.g. full illumination until midnight and from four o’clock till daybreak insertion again. This adjustment is determined with the customer in advance before it is implemented during production. The STREETSUN itself is now available in all RAL colours. New is also the STREETSUN completely in white which is in addition equipped with heat resistant batteries for especially hot regions.
The manufacturer EPS Soltec uses solar power to supply the lamps. Solar cells provide all the energy needed, and this energy is ideal for the light emitting diodes. The LEDs require a voltage of less than 10 V, do not need a 230 V ac power supply and therefore no inverters for converting the voltage.
What’s more, the LEDs do not require secondary optics and can be integrated in almost any luminaire design. The lighting can be adapted to ambient light conditions through dimming, and the color temperature can even be adapted by combining white and yellow LEDs.
LEDs are being used more and more in general lighting applications. Their long and especially predictable life of around 50,000 hours reduces maintenance costs and therefore also operating costs. Because OSRAM LEDs comply with the RoHS directive and do not contain any lead or mercury there are no problems disposing of them at the end of their life. In view of their excellent energy efficiency they will supplement and replace more and more traditional light sources over the coming years. In doing so, they will be making an active contribution to climate protection by reducing CO2 emissions.
