Recent Scenario of Solar Power Street Light ( Spsl ) with Auto-Intensity Control and How to Increase it Efficiency

Solar System has an abundant form of renewable energy which has potential to fulfill billions of watt of electricity. Now a day solar system is required to generate electricity due to sky rocketing price of oil, natural gas, coal. A solar lighting system which can make a 18x3 w lamp glow continuously for about (10) hours if the battery is fully charged has been constructed. Here, solar energy is collected with the aid of a solar panel and thus, a battery is charged during day time with the help of a simple charging circuit. At dusk, they turn on (usually automatically, although some of them include a switch for on, off and automatic) and remain illuminated overnight, depending on how much sunlight they receive during the day time. During night time, this stored energy is used to light. The device can be used for small-scale lighting applications in remote areas that are far away from the power grid. The system has a panel to collect the sun’s energy, a battery to store that energy and a light source to use the energy. The system operates like a bank account. Withdrawals from the battery to power the light source must be compensated for by commensurate deposits of energy form the solar panels. The main objective is that LED Street lighting is a fresh new alternative to traditional street lamps such as LPS, HPS, or MH street lights.


INTRODUCTION
The Street lights are the major requirements in today's life for safety purposes and avoiding accidents during night.Providing street lighting is one of the most important and expensive responsibilities of a city.
Lighting can account for 12-35% of the total energy bill in typical cities worldwide.Street lighting is a particularly critical concern for public authorities in developing countries like India because of its strategic importance for economic and social stability.The fixtures of street lights indirectly have assisted the public and government in reduction of crime rate and accidents in the area.
The term "photovoltaic" comes from the Greek in which photo means "light", and "voltaic", means electric, from the name of the Italian physicist Volta, after whom a unit of electro-motive force, the volt, is named.The term "photo-voltaic" has been in use in English since1849.
The photovoltaic effect was first recognized in 1839 by French physicist A. E. Becquerel.However, it was not until 1883 that the first solar cell was built, by Charles Frits, who coated the semiconductor selenium with an extremely thin layer of gold to form the junctions.The device was only around 1% efficient.Subsequently Russian physicist Alexander Stoletov built the first solar cell based on the outer photoelectric effect (discovered by Heinrich Hertz earlier in 1887).Albert Einstein explained the photoelectric effect in 1905 for which he received the Nobel Prize in Physics in 1921.Russell Ohl patented the modern junction semiconductor solar cell in1946, which was discovered while working on the series of advances that would lead to the transistor.

SOLAR PANELS
The solar panel or PV cell in the solar street light is one of the most essential parts.These cells are available in two types: mono crystalline and poly crystalline.The mono crystalline conversion rate is higher than the poly crystalline.The light energy used by the solar panels from the sun is used to change solar energy into electricity, which can be used in various applications.
Electrical connections of this project are made in series to achieve an o/p voltage and to afford a current facility connections are made in parallel.The majority of the modules use silicon (Si) but most of the solar panels are fixed.

LIGHT EMITTING DIODE
LEDs are used in modern street lights to provide brighter light with low energy consumption.The energy consumption of LED fixture is lesser than the high pressure sodium fixture, which is commonly used in traditional street lights.Compare to the other lamps, LED lights do not produce light in all directions.The design of lamps can be effected by the uniqueness of the LEDs.The single LED o/p is not equal to the incandescent and fluorescent lamps.But, a bunch of LEDs will give bright light than these two lamps.The advantages of LEDs mainly include Eco friendly, durable, zero UV emissions and long life.

RECHARGEABLE BATTERY
Rechargeable battery is a one kind of electrical battery and it has electro mechanical reactions to adjust so it is also called as secondary cell.Generally, there are two kinds of batteries, namely gel cell deep cycle and lead acid battery.A rechargeable battery is used in solar LED street lights, this battery is used to store electricity generated from the solar panel during the sunrise to afford energy in the sunset.The lifetime and capacity of the rechargeable battery are essential as they affect the backup power days of the lights.

CONTROLLER
A controller is a very significant device in solar street light, used to decide the status of the charging and lighting by switch on or switch off.Some recent controllers are pre programmed and it consists of a battery charger, a Led lamp driver, a driver, a secondary power supply, an MCU and a protection circuit.The battery can be controlled by the controller from the under and over charging conditions.The battery can be charged by the power received from the solar panels in the sunrise and while in the sunset it charges the battery.

POLE
A strong pole is mandatory for each and every street light and also for a solar street light.There are various components such as panels, batteries and fixtures fixed on the top of the pole.In this light, the i/p operating voltage is 12V DC which is a nominal system voltage, and the light o/p at the height of 12 feet is a minimum of 09 LUX (unit of luminance).

INTERCONNECTING CABLES
The cable is used to interconnect the LED, solar panel and battery box which is fixed on the top of the pole.This cable is used to connect a Photovoltaic module to the controller, controller to the lamps and battery.The size and length of the cable depend on the current being carried to the LED lights and the height of the pole.The assembling of the entire solar LED street light system can be connected using all the above components which use sun energy to give the power to the LED lamps fixed on street poles.