This blog article deals with the cost-benefit analysis of solar powered street light with high power LED as a light source. The case study in an engineering institute deals with the proposal of replacing existing grid connected street lights with solar powered LED lights. Simple payback period calculation and Life Cycle Costing Analysis of both systems are done to compare the cost effectiveness of solar powered lighting to conventional grid connected lighting system. The comparison between the existing power consumption and the conditions that will prevail if the proposal is implemented is also discussed thus proving that the proposal is efficient from both the economic and energy point of view.
Trends in CO2 emissions from fuel combustion illustrate the need for all countries to shape a more sustainable energy future. According to an estimate of the share of electricity used in India, about 15% of the total electricity generated is used for lighting purposes in various sectors . Photovoltaic (PV) systems offer the possibility of exploiting sun's energy available everywhere, without polluting the environment. The long term power saving, conservation of precious natural resources, flexibility of location and elimination of the need for generating additional power are leading to the fast adoption of PV street lighting systems. Three major types of system configuration exist for solar powered street lighting systems which include Grid connected, Stand-alone and PV hybrid systems. Grid connected systems draw power from the grid during the night and cloudy periods and feed excessive power into the grid during the sunny hours. Standalone systems are defined as autonomous systems that supply electricity without being connected to the utility grid.
The present study investigates the economic feasibility of replacing grid connected street lights in the institute premises that uses non retrofit Compact Fluorescent Lamp (CFL) as
light source with stand alone solar powered high power Light Emitting Diodes (LEDs). The first part of the paper discusses the components and design of the proposed solar powered LED street lighting system. Then the payback period calculation and life cycle costing analysis are presented for the existing grid connected CFL based system and proposed solar powered LED lighting systems, proving the energy saving and cost effectiveness because of the replacement.
DESIGN OF SOLAR POWERED STREET LIGHT
The standalone PV street lighting system comprises Of solar PV module, battery, power electronic converter, control unit, lamp posts and LED lighting unit. During the day, PV panel of the LED solar street lighting system will receive the energy from the sun, then convert to electrical energy and save it in the battery. At night, the energy stored in the battery is released to power the LED streetlights. In India ,the peak equivalent sunshine varies between 5hrs to 7hrs,corresponding to 5kW/m 2 to 7kW/m2 in a day. Hence available sunlight is taken as 5kW/m 2 .The autonomy is defined as the number of days the battery should be able to supply the energy even when there is no sunshine.
Solar energy and solar products have amassed unmatched popularity in the past few decades—so much so that solar products have obsoleted or, at least, curtailed the dominance of quite a few types of traditional lightings already. One such prominent disruption, resulting from the harnessing of solar energy, was that of solar street lights absolutely side lining the use of traditional street lights. Why the aforesaid disruption took place can be understood simply by considering the importance of solar street lights.
The main benefits of solar powered street lights over traditional street lights are:
Impact on the Environment
Solar-driven street lights have no pernicious impacts whatsoever on the environment. The use of solar energy to drive street lights is extremely innocuous and, in fact, far better than the use of traditional street lights driven by electricity which is generated from non-replenishable sources. Moreover, the use of these non-replenishable sources to drive traditional street lights also leads to the production of carbon dioxide as a by-product which is anything but good for the ecological balance.
Visibility and Illumination
Most modern solar-powered street lights are affixed with LED lights or built-in with LEDs. LEDs can be coloured in order to reach the desired CRI, making them resemble sunlight as closely as possible and increasing night-time visibility as a result in the process. Traditional street lights usually have metal halide lamps which are nowhere close to beating the visibility offered by solar-LED street lights.
As far as price is concerned, traditional street lights are a lot cheaper than their solar counterparts. However solar street lights turn out to be a better investment at a cheaper cost if the total money shelled out is considered—from money spent on installation and maintenance to the lamp or light replacements et al. Solar street lights require little or no maintenance. Also, unlike traditional street lights, the solar lights do not require electric poles to be set up explicitly, which is a tardy and expensive procedure per se.
Lifespan of the Lights
Conventional street lights can last only for around 5,000 hours. The total life a solar street light using an LED lamp is as many as around ten times the lifespan of traditional street lights.
Solar driven lights keep the streets illuminated all through the night irrespective of power cuts or grid failures. Traditional street lights very often stop functioning in the event of a grid failure.
The above comparison is enough to indicate which of the two types of street lights are better—it is solar street lights all the way! Most modern solar street lights come integrated with LED lights. The explosively-useful combination of LEDs and solar street lights incorporates the advantages of both the leading technologies of today—namely solar energy and LEDs.
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