Solar Street Lights With Auto Intensity Controller
This system is mainly designed for LED based street lights with auto intensity control. This is done using solar power from photovoltaic cells. Due to the many benefits of using solar energy, many institutions are opting to make use of solar energy. For converting the sunlight to electricity, photovoltaic panels are used for charging the batteries. In order to control charging, charge controller is used.
Intensity of street lights is required to be kept high during the peak hours. As the traffic on the roads tends to decrease slowly in late nights, the intensity can be reduced progressively till morning to save energy. Thus, the street lights switch ON at the dusk and then switch OFF at the dawn automatically. The process repeats every day.
High Intensity Discharge lamps (HID) used for urban street light are based on principle of gas discharge, thus the intensity is not controllable by any voltage reduction method as the discharge path is broken. LED lights are the future of lighting, because of their low energy consumption and long life they are fast replacing conventional lights world over. White Light Emitting Diode (LED) can replace the HID lamps where intensity control is possible by pulse width modulation. The intensity control helps in saving energy during late nights while traffic density on the streets is low. A programmable microcontroller of 8051 family is engaged to provide different intensities at the different times of night using PWM technique, for energy saving for solar based system, using a charge controller for battery charging, overload and deep discharge protection.
Further enhancement to this project can be done by using time programmed dusk to dawn switching that is based on latitude and longitude of a place. This can also be interfaced to a LDR to follow the switching operation.