The document describes a project report for a solar powered LED street light with automatic intensity control. It includes a functional block diagram and explanations of the components, including a solar panel, charge controller circuit, rechargeable battery, voltage divider circuit, and Arduino UNO microcontroller. It also covers the software implementation through simulations of the charge controller and voltage divider circuits. The coding for the real time clock and PWM in Arduino is shown. The hardware implementation, operation, and testing are described as well. Intensity levels are controlled at different times of day and night based on readings from the real time clock.

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Darshil H Shah Vinit G Parikh
A PROJECT REPORT
Submitted By
Darshil Shah (IU1241090051)
Vinit Parikh (IU1241090031)
Department of Electronics & communication
Indus Institute of Engineering and Technology
Ahmedabad
November 2015
Under The guidance of
Prof. Omkar Pabbati
Solar Powered LED Street Light with Auto intensity control

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Darshil H Shah Vinit G Parikh
INDUS UNIVERSITY
Where Practice Meets Theory
Indus Campus, Rancharda, Via: Thaltej, Ahmedabad-382115. Gujarat (INDIA)
CERTIFICATE
DATE: 16/11/2015
This is to certified that the project entitled “Solar Powered LED Street Light
with auto intensity control” submitted to Indus Institute of Engineering and
Technology is bonafide record of work done by DARSHIL H SHAH
(IU1241090051) under my supervision during the academic year 2015
Project supervisor Head of department

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Darshil H Shah Vinit G Parikh
INDUS UNIVERSITY
Where Practice Meets Theory
Indus Campus, Rancharda, Via: Thaltej, Ahmedabad-382115. Gujarat (INDIA)
CERTIFICATE
DATE: 16/11/2015
This is to certified that the project entitled “Solar Powered LED Street Light
with auto intensity control” submitted to Indus Institute of Engineering and
Technology is bonafide record of work done by Vinit G Parikh
(IU1241090031) under my supervision during the academic year 2015
Project supervisor Head of department

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Darshil H Shah Vinit G Parikh
ACKNOWLEDGEMENT
It is us privilege to express our sincerest regards to our project coordinator, Mr. Omkar
Pabbati, for their valuable inputs, able guidance, encouragement, whole-hearted cooperation
throughout the duration of our project.
We deeply express sincere thanks to our Head of Department Prof. R N Mutagi for
encouraging and allowing us to present the project on the topic
“Solar powered LED Street light with auto intensity control”
We take this opportunity to thank all lecturers who contributed their valuable advice and
helped to complete this project successfully.

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ABSTRACT
This report describes the design of the “Solar Powered LED street Light with auto-
intensity control” The project based on 2 modules.
1. Charge controller circuit
2. Load intensity control circuit
Using 18v solar panel we will charge 12v battery. The charge controller circuit can prevent
the battery to flow high current through it after than we will convert 12v to 5v using voltage
divider circuit
Using RTC (Real Time Control) can generate seconds, minutes, hours, date of the month,
month, day of the week, and year with leap-year
To perform PWM we can generate different analogue voltages Using ArduinoUNO software.
The circuit of the Project is designed, simulated and built with hardware. The simulation
results and design details are provided. Circuit diagram of our project is successfully tested
on hardware.

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Table of Contents
INTRODUCTION.......................................................................................................................................1
Chapter 1.................................................................................................................................................2
Functional block diagram with explanation of each Block.....................................................................2
1.1 Block Diagram:.......................................................................................................................3
1.2 Explanations of Each Block: ....................................................................................................4
Chapter 2.................................................................................................................................................5
Charge controller circuit .........................................................................................................................5
2.1 Operation of circuit diagram:..................................................................................................6
2.2 Advantages:.............................................................................................................................6
2.3 Limitations: .............................................................................................................................6
2.4 Application:.............................................................................................................................6
Chapter 3.................................................................................................................................................7
Software Implementation.......................................................................................................................7
3.1 Simulation of charge controller circuit: ..................................................................................8
3.2 Simulation of Voltage divider circuit:......................................................................................9
3.3 Coding of Controller in Arduino UNO for RTC (Real Time Clock):.........................................10
3.4 Coding of Controller in Arduino UNO for PWM:...................................................................13
Chapter 4...............................................................................................................................................14
Hardware Implementation ...................................................................................................................14
4.1 Operation of circuit diagram:................................................................................................15
4.2 Testing of Hardware:.............................................................................................................16
4.3 Hardware component List: ...................................................................................................17
Chapter 5...............................................................................................................................................18
Applications, References, Future Scopes..............................................................................................18
5.1 Advantages:...........................................................................................................................19
5.2 Disadvantages:......................................................................................................................19
5.3 Applications: .........................................................................................................................19
5.4 Conclusion:............................................................................................................................20
5.5 Future Scope:........................................................................................................................21
References: ...........................................................................................................................................22
APPENDIX-A - LIST OF FIGURES.............................................................................................................23
APPENDIX-B - LIST OF TABLE.................................................................................................................23

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Darshil H Shah Vinit G Parikh
INTRODUCTION
The project is designed for LED based street lights with auto intensity control using solar
power from photovoltaic cells. As awareness for solar energy is increasing, more and more
individuals and institutions are opting for solar energy. Photovoltaic panels are used for
charging batteries by converting the sunlight into electricity. A charge controller circuit is
used to control the charging and prevent the battery to overcharging from the solar panel.
Battery charger should have over voltage protection, short circuit protection and reversed
polarity protection.
Intensity of street lights is required to be kept high during the peak hours. At late night
intensity of light should be max after some time the intensity can be reduced progressively till
morning to save energy. Thus final it completely shuts down at morning 6, and again resumes
at 6pm in the evening. The process repeats every day.
We Used voltage divider circuit to convert 12V to 5V because controller can understand 5V.
The microcontroller contains programmable instructions which controls the intensity of street
lights based on the PWM (Pulse width modulation) signals generated. To generate PWM
signal at different time we used RTC.
Real-time clock (RTC) counts seconds, minutes, hours, date of the month, month, day of the
week, and year with leap-year. RTC will consume power from microcontroller. RTC is use to
detect Automatic power-fail in the circuitry.
From the dusk with full intensity till 11pm from 6pm and at 6’o clock to 8’o clock 60%, 8’o
clock to 12’o clock 70% 12 mid night it is 100% duty cycle, 1’o clock to 4’o clock 60%, 4’o
clock to 6’o clock 60% and finally OFF at the dawn.
LED lights are the future of lighting, because of their low energy consumption and long life
they are fast replacing conventional lights world over Hence we used LEDs to control the
intensity of light.

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Chapter 1
Functional block diagram with explanation of each Block

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1.1 Block Diagram:
LED BANK
FIG. 1.1 Block diagram
Solar
Panel
Charge
Controller
Circuit
Rechageable
Battery
Voltage
Divider
Circuit
Arduino
UNO

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1.2 Explanations of Each Block:
Solar Panel: A solar panel is a collection of solar cells. The solar panel converts the solar
energy into electrical energy. Output of the solar panel is its power which is measured in
terms of Watts or Kilo watts. Solar power uses multiple reflectors to collect more sun’s
thermal energy. Thermal energy collected through the day to perform different operations.
Performance of the solar panel depends on a number of factors like climate, conditions of the
sky, orientation of the panel, intensity and duration of sunlight and its wiring connections.
Charge controller circuit: If the battery voltage is below 12V, then the current from LM317
IC flows to the battery. The current flow to the battery stops when the battery voltage rises to
13.5V. Hence charge controller circuit will prevent the battery to flow high current through it.
Rechargeable Battery: A rechargeable battery, storage, secondary battery or accumulator is
a type of electrical battery which can be charged, discharged into a load, and recharged many
times, while a non-rechargeable or primary battery is supplied fully charged, and discarded
once discharged. Several different combinations of electrode materials and electrolytes are
used, including lead–acid, nickel cadmium (NiCd), nickel metal hydride (Ni-MH), lithium
ion (Li-ion), and lithium ion polymer (Li-ion polymer).
Voltage Divider circuit: A voltage divider is a simple circuit which turns a large voltage into
a smaller one. Using just two series resistors and an input voltage, we can create an output
voltage that is a fraction of the input. Voltage dividers are one of the most fundamental
circuits in electronics equation of circuit is shown in fig.
Arduino UNO: Micro-controller will control the intensity of light at different time slots.
Micro controller circuit will generate PWM waves at a particular time using RTC (Real Time
Clock) these system provide sets of digital and analog I/O pins that can be interfaced to the
street light circuit. Operating voltage of Arduino UNO is 5v so that we will convert 12v from
Battery to 5v.

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Chapter 2
Charge controller circuit

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2.1 Operation of circuit diagram:
 This automatic battery charger circuit design mainly involves two sections – power
supply section and load comparison section.
 If the battery voltage is below 12V, then the current from LM317 IC flows through
the resistor R5 and diode D5 to the battery. At this time Zener diode D6 will not
conduct because battery takes all the current for charging.
 When the battery voltage rises to 13.5V, the current flow to the battery stops and
zener diode gets the sufficient breakdown voltage and it allows the current through it.
Now the base of the transistor gets the sufficient current to turn on so that the output
current from LM317 voltage regulator is grounded through the transistor Q1. As a
result Red LED indicates the full of charge.
2.2 Advantages:
 The battery charger circuit is simple and cost effective.
 Over voltage and current protection.
 Over temperature protection.
 The system is easily portable.
 Automatically charges the battery and stops charging when battery is fully charged.
 Avoids battery discharge when power failed.
2.3 Limitations:
 It takes long time for charging the battery
 This circuit is tested in simulation software and may require some practical changes
2.4 Application:
 This automatic battery charger is used to charge 12V Lead-acid batteries.
 Used to charge car batteries since IC output voltage is variable.
 Used to charge toy auto mobile batteries with a little modification.

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Chapter 3
Software Implementation

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3.1 Simulation of charge controller circuit:
I. When POT is 100 %( Not Charging)
FIG. 3.1.1 controller circuit-I
II. When POT is 30 %( Full Charge)
FIG. 3.1.2 controller circuit-II

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3.2 Simulation of Voltage divider circuit:
Controller Arduino UNO can understand 5v. So we require converting 12V from battery to 5V using
Voltage divider circuit.
Vout=(R2/R1+R2)*Vin
FIG.3.2.1 Voltage divider circuit

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3.3 Coding of Controller in Arduino UNO for RTC (Real Time Clock):
SET TIME:
#include <Wire.h>
#include <Time.h>
#include <DS1307RTC.h>
const char *monthName[12] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
tmElements_t tm;
void setup() {
bool parse=false;
bool config=false;
// get the date and time the compiler was run
if (getDate(__DATE__) && getTime(__TIME__)) {
parse = true;
// and configure the RTC with this info
if (RTC.write(tm)) {
config = true;
}
}
Serial.begin(9600);
while (!Serial) ; // wait for Arduino Serial Monitor
delay(200);
if (parse && config) {
Serial.print("DS1307 configured Time=");
Serial.print(__TIME__);
Serial.print(", Date=");
Serial.println(__DATE__);
} else if (parse) {
Serial.println("DS1307 Communication Error :-{");
Serial.println("Please check your circuitry");
} else {
Serial.print("Could not parse info from the compiler, Time="");
Serial.print(__TIME__);
Serial.print("", Date="");
Serial.print(__DATE__);
Serial.println(""");
}
}

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void loop() {
}
bool getTime(const char *str)
{
int Hour, Min, Sec;
if (sscanf(str, "%d:%d:%d", &Hour, &Min, &Sec) != 3) return false;
tm.Hour = Hour;
tm.Minute = Min;
tm.Second = Sec;
return true;
}
bool getDate(const char *str)
{
char Month[12];
int Day, Year;
uint8_t monthIndex;
if (sscanf(str, "%s %d %d", Month, &Day, &Year) != 3) return false;
for (monthIndex = 0; monthIndex < 12; monthIndex++) {
if (strcmp(Month, monthName[monthIndex]) == 0) break;
}
if (monthIndex >= 12) return false;
tm.Day = Day;
tm.Month = monthIndex + 1;
tm.Year = CalendarYrToTm(Year);
return true;
}

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READ TIME:
#include <Wire.h>
#include <Time.h>
#include <DS1307RTC.h>
void setup() {
Serial.begin(9600);
while (!Serial) ; // wait for serial
delay(200);
Serial.println("DS1307RTC Read Test");
Serial.println("-------------------");
}
void loop() {
tmElements_t tm;
if (RTC.read(tm)) {
Serial.print("Ok, Time = ");
print2digits(tm.Hour);
Serial.write(':');
print2digits(tm.Minute);
Serial.write(':');
print2digits(tm.Second);
Serial.print(", Date (D/M/Y) = ");
Serial.print(tm.Day);
Serial.write('/');
Serial.print(tm.Month);
Serial.write('/');
Serial.print(tmYearToCalendar(tm.Year));
Serial.println();
} else {
if (RTC.chipPresent()) {
Serial.println("The DS1307 is stopped. Please run the SetTime");
Serial.println("example to initialize the time and begin running.");
Serial.println();
} else {
Serial.println("DS1307 read error! Please check the circuitry.");
Serial.println(); }
delay(9000); }
delay(1000);
}
void print2digits(int number) {
if (number >= 0 && number < 10) {
Serial.write('0'); }
Serial.print(number);
}

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3.4 PWM in Arduino UNO:
FIG.3.4 PWM
The green lines represent a regular time period. This duration or period is the inverse of the
PWM frequency. In other words, with Arduino PWM frequency at about 500Hz, the green
lines would measure 2 milliseconds each. A call to analog write () is on a scale of 0 - 255,
such that analogWrite (255) requests a 100% duty cycle (always on), and analogWrite (127)
is a 50% duty cycle (on half the time).

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Chapter 4
Hardware Implementation

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4.1 Operation of circuit diagram:
The system consists of two circuits – the Charge control circuit and the load intensity control
circuit.
The charge control circuit consists of 4 parts - overcharge indication, over load detection with
protection and low battery voltage detection with indication. IC-LM317t adjustable three-
terminal positive-voltage regulator .And it is capable of supplying more than 1.5A over an
output-voltage range of 1.25 V to 37 V.
The load intensity control part consists of the controller-Arduino UNO which controls the
power supply to the load through the transistor and RTC (Real Time Clock). RTC can
generate PWM waves at particular time. So as to vary the intensity of the led’s. Here an array
of led’s is connected as the load.
Timings with intensity Ratio:
Timings 6’o to 8’o clock 8’o to 12’o clock 12’o clock 1’o to 4’o clock 4’o to 6’o clock
Intensity 60% 80% 100% 80% 60%
Table 4.1.1 Time with Intensity

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4.2 Testing of Hardware:
1) Controller circuit I
FIG.4.2.1 Controller circuit I
2) RTC circuit
FIG.4.2.2 RTC Circuit

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4.3 Hardware component List:
PART LIST QUANTITY PRICE
Solar panel (18V) 1 1000
Arduino UNO 1 400
Capacitor Box 1 70
Rechargeable Battery (12V) 1 1000
Zener diode (11v,1w) 1 5
LM317t Regulator 1 10
Potentiometer (10kohms) 1 20
Diode (1N4007) 2 5
LEDs (Small, Big) 10 40
RTC (Real Time Clock) 1 20
Crystal 1 10
Resistor Box 1 50
Transistors 2 5
Heat sink 3 5
Male to Female wire 6 30
Table 4.3.1 Component list

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Chapter 5
Applications, References, Future Scopes

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5.1 Advantages:
 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 is minimized.
 This is a non-polluting source of electricity.
 Separate parts of solar system can be easily carried to the remote areas.
5.2 Disadvantages:
 Initial investment is higher compared to conventional street lights.
 Risk of theft is higher as equipment costs are comparatively higher.
 Snow or dust, combined with moisture can accumulate on horizontal pv-panels and
reduce or even stop energy production.
 Rechargeable batteries will need to be replaced several times over the lifetime of the
fixtures adding to the total lifetime cost of the light.
 The batteries have to be replaced from time to time.
5.3 Applications:
This system is designed for outdoor application in un-electrified remote rural areas. This
system is an ideal application for campus and village street lighting.
Solar Street Lighting System is an ideal lighting system for Roads, Yards, Residential
Colonies, Townships, Corporate Offices, Hospitals, Educational Institutions and Rural
Electrification.

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 Street Lighting
 Pathway Lighting
 Private Road Lighting
 Sidewalk Lighting
 Farm & Ranch Lighting
 Perimeter Security Lighting
 Campus Lighting
 Gate Lighting
 Park Lighting
 Wildlife Area
 Remote Area Lighting
 Jogging and Bike Path Lighting
5.4 Conclusion:
The solar energy is one of the important and major renewable sources of energy and has also
proven it useful in functioning of applications like street lights.
Solar powered automatic street light controller is one of the applications of electronics to
increase the facilities of life. The use of new electronic theories has been put down by
expertise to increase the facilities given by the existing appliance. Here the facility of
ordinary street light is increased by the making it controlled automatically
The charge control is necessary in order to achieve safety and increase the capacity of the
battery. In cities, currently thousands of street lights are operated and the yearly electricity
maintenance cost is very high.
The initial cost and maintenance can be the draw backs of this project. With the advances in
technology and good resource planning the cost of the project can be cut down and also with
the use of good equipment the maintenance can also be reduced in terms of periodic checks.
It saves around 40% of electricity from per street light. So throughout the world if we use this
concept then it will eliminate the energy crisis to a larger extent.
It is eco-friendly and utilizes the renewable source of energy very well.

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5.5 Future Scope:
The Solar Powered LED Streetlight with Auto Intensity Control can control the electric
charge and intensity of lights.
This project can be enhanced by using with timer based products and photo sensor based
products.
We can use solar tracking system for fast charging.
In monsoon season solar light is more difficult so that we use extra batteries in series to save
more power.
To improve lighting we use LED Panel.

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References:
http://www.ijireeice.com/upload/2015/june-15/IJIREEICE%206.pdf
http://www.kslubiwmp.com/docs/Watershed%20works/SolarStreetLight.pdf
http://www.timeanddate.com/astronomy/india/ahmadabad
https://www.sparkfun.com/datasheets/Components/DS1307.pdf
http://www.ti.com/lit/ds/symlink/lm317.pdf

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APPENDIX-A - LIST OF FIGURES
NO. TITLE PAGE NO.
1.1 Block Diagram 2
3.1.2 controller circuit-I(simulated) 8
3.1.2 controller circuit-II(simulated) 8
3.2.1 Voltage divider circuit 9
3.4 PWM 13
4.2.1 Controller circuit 17
4.2.2 RTC circuit 17
APPENDIX-B - LIST OF TABLE
4.1.1 Time with Intensity 13
4.3.1 Hardware Component 15