Solar Powered Street Lights

Are solar LED street lights a worthy investment?

Solar LED lights are efficient the way solar energy is extremely efficient, especially now that the world is pushing for a more environmentally-free energy system to avoid the adverse effects of climate change. According to World Energy, just the average global solar radiation per year can produce just as much energy needed as 140 m3 of natural gas, 200 kg of coal, or a barrel of oil. This means, under the right optimization process, solar energy can indeed replace modern energy sources we have today.

High Level Overview of Solar Street Lights –

Basic components system consists of:

(1) Solar cell

(2) LED lamps

(3) Light pole

(4) Control box (charger, controller, battery)

Operations Basics –

According to principle of photo-voltaic effect, the solar panels receive solar radiation during the day time and then convert it into electrical energy through the charge and discharge controller, which is finally stored in the battery. When the light intensity reduced to about 10 lx during night and open circuit voltage of the solar panels reaches at a certain value, the controller has detected voltage value and then act, the Battery offer the energy to the LED light to drive the LED emits visible light at a certain direction. Battery discharges after certain time passes, the charge and discharge controller will act again to end the discharging of the battery in order to prepare next charging or discharging again

Key Considerations for Optimum Solar Power yield –

1. Appropriate Angle of panel installation
2. Selection of Battery
3. Appropriate quality of circuit and LED to avoid overheating
4. Analysis of Geographical Conditions

Brief Comparison of Solar LED street light Vs High Pressure Sodium Street Lights: –

Herein we consider 100W LED and 250W high pressure sodium lamp as a comparison example.

1) The initial luminous flux of 100W LED lamps is 11000lm. 10% loss because of the lens, 10% loss because of the driver ,the actually luminous flux of lamp is 8910lm, the total consumption power of Lamp is 110W. Therefore, the efficiency of LED street light is 81lm / W.

2) The initial luminous flux of 250W HPS lamps is 25000lm. 30% loss because of light use,20% loss because the power supply, 10% loss because of such as reflector etc. So the actually luminous flux of lamp is 12600lm. The total consumption power of Lamp is about 300w. So the efficiency of HPS street light is 42lm / W.

We have get the final value of luminous efficiency through the analysis and comparison above. The luminous efficiency of 100w LED is almost 2 times of the efficiency of HPS. This is the reasons that we can use 100W LED lamps to replace 250W HPS.

Conclusion: –

As per the below key advantages, Solar street lights are being proved to be the best alternative to conventional methods –

• Solar street lights are independent of the utility grid. Hence, the operation costs are minimized.
• Solar street lights require much less maintenance compared to conventional street lights.
• Since external wires are eliminated, risk of accidents are minimized.^[2]
• This is a non-polluting source of electricity
• Separate parts of solar system can be easily carried to the remote areas
• It allows the saving of energy and also cost.