The problems with implementing solar powered street light projects
Afam Nnaji
Publisher
Considering the importance of street lights I will focus on this one alone on this piece. Let us sort out a few facts on solar energy or power generation.
1. It is expensive to produce electricity from solar power hence the need to get things right the first time.
2. Quite a lot of solar panels in the market are not very reliable due to a lot of factors ranging from adherence to standards to cheap components. A good solar powered street light project must provide enough light to illuminate the area each solar powered lamp is supposed to illuminate, must provide this light when it is needed (when darkness comes knocking) and must store enough energy in the battery backup for use during the time of low or no sunshine like in the raining season.
Without getting into any technical terms here I will explain why some of the solar powered street lights have already run into problems as regards reliability and performance. Incorrect sizing of components that make up a complete working solar energy generation, storage and supply system.
First, the load (in this case) the bulb or LED (light emitting diodes) must be correctly sized to deliver the needed illumination when it is needed. Then the number of hours the illumination is supposed to be provided is calculated and a good estimate settled for based on the number of sun hours in any given day and allowances made for those days you may be without the sun shining.
Once you are ok with these calculations you then choose a solar panel that will not only deliver the needed power but extra or excess so that you can store the energy in the backup battery.
So, if for example you require a 30W bulb or LED for illumination it would be wrong to get a 40W solar panel unless you are sure that the number of hours you get the sunlight is close to the number of hours you require the illumination and even if this holds true you will surely have a non existent backup even for a single day without sun.
So, the solar panel must be oversized, a good charge controller must be used and a battery bank with enough storage capacity must b used so that the energy you want to store will have a place to go for storage. If you have done your calculations and you need to store 150 amps in a battery and you get a 75 Ah battery it means that you will be wasting 50% of what you are producing as simple as that.
In conclusion, while solar energy generation is expensive it is the most suitable for solar powered street lights considering the low maintenance overhead and long life span of LEDs as against the old incandescent or even halogen based lighting units. However, incorrect sizing of both the load and the components can effortlessly turn a viable cost effective solution into a nightmare because should you go wrong with the calculations including energy losses in conversion stages (where applicable) or interfacing components you may just realize that changing the solar panel to deliver more energy may not be enough as you would have to also consider changing the battery to be able to store what is being generated and the lighting unit itself may most likely be changed too.
Apart from these obvious parameters that tend to affect the success or otherwise of solar energy based projects another major issue is energy wastage? Why would a solar powered street light be on during the daytime when you barely have enough energy stored in the backup battery? Any good reason for this? Simply buying solar energy components from manufacturers who claim to be No 1 in the alternative energy business is not enough.
Adequate and relevant knowledge are needed to be able to ascertain the correctness or otherwise of claims made by manufacturers as these technologies are based on best practices, standards and/or protocols which manufacturers are expected to follow but in reality the adherence or compliance to these standards may be far from the expected considering the fact that manufacturers implement them based on their experience, technical know how or other economic factors.
