Solar Street Lights

Example: Noble Energy Solar Technologies in India

Noble Energy Solar Technologies (NEST) is the winner of the Ashden Awards for Sustainable Energy for light in 2005 and the inventor of the Aishwarya lamp, which was tested both in laboratory test of GIZ (price-performance winner) and in various field tests. NEST installed solar streetlights in a village, in which the government has installed poles before 15 years. But the people wait for electricity since then. The solar streetlights were free of charge. Observed impacts are: places beneath solar street lights became meeting points and children do their homework there.

Tips and Tricks

• In many designs, the battery can be buried in the foundations. Advantages: lower risk of theft and vandalism, lower temperature (=longer life). Disadvantages: access for maintenance is more difficult, water may enter but not leave. Weigh these against each other for your project.
• Have proper foundations cast in concrete, and have these works supervised. Bury wooden trunks around the foundations, or have large stones put, in order to minimise danger of horsecarts, cars etc. driving against the lamp.
• Choose your lamp according to local preferences. Sodium lamps have the highest efficiency, but their light is yellowish, which the target group may not like.
• Prefer programmable charge controllers over simple night-light function charge controllers, so that you can program the lamp to come on some time after sunset and go off some time before sunrise. Many programmable charge controllers allow for a period at night during which the streetlight is off. This saves electricity, but people may prefer to have light the whole night.
• Charge controller must be protected against insects.
• Take care of theft protection for the battery. The battery could for example be buried into the foundations (consider aeration requirements) or attached to the mast. You could protect the box by means of a padlock.  Anti-theft screws will do as well; reopening the boxes will require special tools (and replacement screws), but they are not as prone to corrosion as padlocks.
• Ensure that the person in charge of maintenance has a ladder that allows cleaning the panel.
• Placement of the lamp: try to avoid places that could be flooded or in which the battery box is exposed to sunlight. Check whether different groups within the village compete for the lamps, and whether the proposed location is not just a foul compromise. (It could, for example, be on the border of two parts of the village, not benefiting either.)
• Try to make a factory reception in Germany, especially when ordering large quantities. Have one lamp assembled and mounted by the supplier before you, in order to check dimensions, presence of all necessary material etc.

Pitfalls and Common Sources of Failure

Corroded Padlocks

Corroded padlock

Batteries and charge controllers are often stored in a metal box and need to be protected against theft. The means of protection often is a padlock. The mechanism is prone to corrosion. This problem may be mitigated by greasing of the closing mechanism.

Improper Panel Maintenance

Birds nesting on a solar street light

Panel maintenance may be insufficient for different reasons: improper assignment and / or assumption of responsibilities, incompetence, lack of awareness, etc. More profane reasons exist, such as the simple lack of ladders or buckets. The photo shows a sign of lack of maintenance: birds nesting on the back of a panel support structure. This may lead to pollution of the panels (bird droppings cause partial shadowing which results in danger of hot spot formation) or damage to wiring.