TABLE OF CONTENTS:

TITLE OF THE PROJECT……………………..……………...1

DECALARTION……………………………………..............2

CERTIFICATE…………………………………………………...…3

ACKNOWLEDGEMENT ……………………………………………………4

ABSTRACT……………………………………………………………………....7

LITRATURE REVIEW ……………………………………………………….8

SCOPE OF THE PROJECT……………………………..…………………………...9

BACKGROUND OF THE STUDY ……………………………...........…10

PURPOSE OF THE PROJECT …………………………………………….11

CHAPTER 1: INTRODUCTION…………………………………..13

1.1 WORKING..................................................................15

1.2 BASIC CIRCUIT DIAGRAM......................................17

1.3 FLOW CHART.............................................................18

5
CHAPTER 2: HARDWARE MODEL……………………………………….19

2.1 BLOCK DIAGRAM OF SOLAR TRACKER…….….….….19

2.2 EXPLANATION OF BLOCK DIAGRAM…..….…….........20

2.3 ARDUINO UNO………….……..………..………………….21

2.4 PIN DIAGRAM OF ARDUINO UNO……………….………22

2.5 LDR…………………………………………..…….…………23

2.6 SERVO MOTOR…………………………………...…………25

2.7 H-BRIDGE……..………………………………….………….26

2.8 RESISTOR…………..…………………………….………….28

2.9 BATTERY CAP………………..………………….………….29

2.10 BATTERY………….………..…......……………….……….29

2.11 SWITCH………………………...….…………….…………..30

CHAPTER 3: SOFTWARE PROGRAM MODEL………………………….31

3.1 PROGRAM CODE……………………………….…..…….31

3.2 DESCRIPTION OF THE SOFTWARE PROGRAM………34

CHAPTER 4: DISCUSSION AND CONCLUSION…………………………35

4.1 ABOUT SOLAR TRACKER AND CONNECTED LOAD……34

6
4.2 DUAL AXIS MOVEMENT OF SOLAR TRACKER……….…36

4.3 BENEFITS AND DEMERITS OF SOLAR ENERGY……....…37

4.4 OBSERVATION AND RESULTS…………….………..………39

4.5 CONCLUSION……………………….………………………….41

APPENDX …………………………………………………………………42

A1 SPECIFICATIONS OF THE HARDWARE REQUIRMENT…..42

AVENUES FOR FUTURE WORK…………………………………45

REFERENCES………………………………………………………46

7
 ABSTRACT
Natural energy sources have become very important as an alternative to
as the energy demand and the environmental problems increase, the
conventional energy sources. The renewable energy sector is fast
gaining ground as a new growth area for numerous countries with the
vast potential it presents environmentally and economically. Solar
energy plays an important role as a primary source of energy,
especially for rural area. This project aims at the development of
process to track the sun and attain maximum efficiency using arduino
Uno and LDR Sensor for real time monitoring. The project is divided
into two stages, which are hardware and software development. In
hardware development, four light dependent resistor (LDR) has been
used for capturing maximum light source. Two servo motor has been
used to move the solar panel at maximum light source location sensing
by LDR. The performance of the system has been tested and compared
with static solar panel.

This project describes the design of a low cost, solar

tracking system. In this project a dual axis solar tracking system has
been developed by which more energy from the sun can be harnessed.
In this project, an arduino Uno has been used as the main controlling
unit. To detect the position of the sun on the sky, four LDRs have been
used and to rotate the orientation of the Solar PV panel a two servo
motor has been used. The sensors and servo motor have properly been
inte1 faced. The servo motor has been mechanically coupled with the
PV panel. The whole system has been assembled together and its
performance has been tested. This tracker changes the direction of the
solar panel based on the direction of the sun facing to the panel
successfully. Dual axis solar tracker tracks the sun on daily basis and
makes the solar panel more efficient.

8
 LITERATURE REVIEW
Hossein Mousazadeh et Al., [ (2011), Journal of Solar Energy
Engineering,Vol.133 ] studied and investigated maximization of
collected energy from an on-board PV array, on a solar assist
plug-in hybrid electric tractor (SAPHT). Using four light
dependent resistive sensors a sun tracking system on a mobile
structure was constructed and evaluated. The experimental tests
using the sun-tracking system showed that 30% more energy was
collected in comparison to that of the horizontally fixed mode.
Four LDR sensors were used to sense the direct beams of sun.
Each pair of LDRs was separated by an obstruction as a shading
device. A microcontroller based electronic drive board was used
as an interface between the hardware and the software. For driving
of each motor, a power MOSFET was used to control the
actuators. The experimental results indicated that the designed
system was very robust and effective.

K.S. Madhu et al., (2012) International Journal of Scientific &

Engineering Research vol. 3, 2229–5518, states that a single axis
tracker tracks the sun east to west, and a two-axis tracker tracks
the daily east to west movement of the sun and the seasonal
declination movement of the sun. Concentrates solar power
systems use lenses or mirrors and tracking systems to focus a large
area of sunlight into a small beam. PV converts light into electric
current using the photoelectric effect. Solar power is the
conversion of sunlight into electricity. Test results indicate that the
increase in power efficiency of tracking solar plate in normal days
is 26 to 38% compared to fixed plate. And during cloudy or rainy
days it’s varies at any level.

9
 SCOPE OF WORK IN THE PROJECT
The solar project was implemented using two servo motors. The
choice was informed by the fact that the motor is fast, can sustain
high torque, has precise rotation within limited angle and does not
produce any noise. The Arduino IDE was used for the coding.
Kolkata has coordinates of 22.5726°N, 88.3639°E and therefore
the position of the sun will vary in a significant way during the
year. In the tropics, the sun position varies considerably during
certain seasons. There is the design of an input stage that
facilitates conversion of light into a voltage by the light dependent
resistors, LDRs. There is comparison of the two voltages, and then
the microcontroller uses the difference as the error.

The servo motor uses this error to rotate through a corresponding

angle for the adjustment of the position of the solar panel until
such a time that the voltage outputs in the LDRs are equal. The
difference between the voltages of the LDRs is received as analog
readings. Function of the processor: The analog readings are
converted to integer values by ADC input ports which is
compared in order to get the difference value for motor
movement. The difference is transmitted to the servo motor and it
thus moves to ensure the two LDRs are an equal inclination. This
means they will be receiving the same amount of light, and the
Solar panel will receive the sunlight at 90°, (the plane of PV panel
will make an angle 90° with the Sun, and the perpendicular drawn
on the plane makes an angle 0° with the Sun, to ensure maximum
illumination: Lambert’s cosine Law) The procedure is repeated
throughout the day. Tracker systems work on two simple
principles together. One being, the normal principle of incidence
and reflection on which our tracker works and the other is the
principle on which the solar (PV) panel works, which will produce
electricity. Both these principles can be combined and as a result
of which it can produce nearly double the output that the panel
specifies normally.
10
 BACKGROUND OF THE STUDY

Demand of electrical energy is increasing day by day. So many different power

sources are being used in modern power system. Researchers are trying to make
power system more and more efficient. Solar tracking system is also a part of that
research to make power sources more efficient. Solar tracking is used to extract
more power from solar panels by giving solar panels maximum appearance to sun
light. Different techniques have been developed for solar tracking system.
A solar tracker is a device that orients a payload toward the Sun. Payloads are
usually solar panels, parabolic troughs, Fresnel reflectors, lenses or the mirrors of a
heliostat.
For flat-panel photovoltaic systems, trackers are used to minimize the angle of
incidence between the incoming sunlight and a photovoltaic panel. This increases
the amount of energy produced from a fixed amount of installed power generating
capacity. In standard photovoltaic applications, it was predicted in 2008-2009 that
trackers could be used in at least 85% of commercial installations greater than one
megawatt from 2009 to 2012.
In concentrator photovoltaic (CPV) and concentrated solar power (CSP)
applications, trackers are used to enable the optical components in the CPV and
CSP systems. The optics in concentrated solar applications accepts the direct
component of sunlight light and therefore must be oriented appropriately to collect
energy. Tracking systems are found in all concentrator applications because such
systems collect the sun's energy with maximum efficiency when the optical axis is
aligned with incident solar radiation.
This tracking movement is achieved by coupling a stepper motor to the solar panel
such that the panel maintains its face always perpendicular to the sun to generate
maximum energy. This is achieved by using a programmed microcontroller to
deliver stepped pulses in periodical time intervals for 12 hours for the stepper
motor to rotate the mounted panel in bidirectional and then return to the start point
for next day light as desired

11
 PURPOSE OF PROJECT
The purpose of this work is to build a device that when sun is high in the sky, the
tracking system must follow its position. An active control can help achieve this
purpose by using time movements. The system need to be automatic thus making it
simple and easy to use. The operator interference need to be negligible and must be
restricted.

12
CHAPTER 1
1. INTRODUCTION

The conversion of solar light into electrical energy represents one

of the most promising and challenging energetic technologies, in
continuous development, being clean, silent and reliable, with
very low maintenance costs and minimal ecological impact.
A photovoltaic panel is a device used to capture the suns
radiation. These panels consist of an array of solar cells. The solar
cells are made up of silicon (sand). They are then connected to
complete a photovoltaic (solar) panel. When the sun rays are
incident on the solar cells, due to the photovoltaic effect, light
energy from the sun is used to convert it to electrical energy. We
know that most of the energy gets absorbed, when the panel’s
surface is perpendicular to the sun. Stationary mounted PV
(photo voltaic) panels are only perpendicular to sun once a day
but the challenge for is to get maximum energy from the source,
so for it we use trackers on which the whole system is mounted. In
tracking system, solar panels move according to the movement of
sun throughout the day. There are three methods of tracking:
active, passive, chronological and manual tracking systems. In
active tracking system, the position of the sun is determined by
the sensors.
These sensors will trigger the motor to move the mounting
system so that the panels will always face the sun rays
perpendicular to it throughout the day.
But in this system it is very difficult for sensors to
determine the position of sun in cloudy days. So it is not a very
accurate. In its Passive tracking systems, which determines the
position of the sun by moving the panels in response to an

13
imbalance pressure between the two points at both ends of the
trackers? The imbalance pressure caused by solar heat creates a
gas pressure on a low boiling point compressed gas fluid that is
driven to one side or the other accordingly, which then moves the
system.
This method is also not accurate as the shade/reflectors that
are used to reflect early morning sunlight to "wake up" the panel
and tilt it towards the sun can take nearly an hour to do so. A
chronological tracker is a timer-based tracking system whereby
the structure is moved at a fixed rate throughout the day.
The theory behind this is that the sun moves across the sky at
a fixed rate. Thus the motor or actuator is programmed to
continuously rotate at a, slow average rate of one revolution per
day (15degrees per hour). This method of sun-tracking is very
accurate. However, the continuous rotation of the motor or
actuator means more power consumption and tracking the sun.
In manual tracking system, drives are replaced by operators who
adjust the trackers. This has the benefits of robustness, having
staff available for maintenance and creating employment for the
population in the vicinity of the site.
Tracker systems follow the sun throughout the day to
maximize energy output. The Solar Tracker is a proven dual-axis
tracking technology that has been custom designed to integrate
with solar modules and reduce system costs. The Solar Tracker
generates up to 40% more energy than fixed mounting systems
and provides a bankable energy production profile preferred by
utilities.

14
1.1 WORKING PRINCIPLE
1. Resistance of LDR depends on intensity of the light and it varies
according to it.
2. The higher is the intensity of light, lower will be the LDR resistance
and due to this the output voltage lowers and when the light intensity
is low, higher will be the LDR resistance and thus higher output
voltage is obtained.
3. A potential divider circuit is used to get the output voltage from the
sensors (LDRs).

The circuit is shown here:-

FIG 1.1 :- LIGHT SENSOR CIRCUIT

15
4 The LDR senses the analog input in voltages between 0 to 5 volts and
provides a digital number at the output which generally ranges from 0 to
1023.

5 Now this will give feedback to the microcontroller using the arduino
software (IDE).
The servo motor position can be controlled by this mechanism which is
discussed later in the hardware model.

16
1.2 BASIC CIRCUIT DIAGRAM
An overview of the required circuit for the Dual-axes solar tracker is shown here.
The 5V supply is fed from an USB 5V dc voltage source through Arduino Board.
Servo X: Rotates solar panel along X direction
Servo Y: Rotates solar panel along Y direction

FIG 1.2 :-CIRCUIT DIAGRAM

17
1.3 FLOW CHART

FIG 1.3 :- FLOW CHART DIAGRAM

18
CHAPTER 2
HARDWARE

2.1 BLOCK DIAGRAM OF SOLAR TRACKER

FIG 2.1 :- SOLAR TRACKER

19
2.2 EXPLANATION OF THE BLOCK DIAGRAM
As we see in the block diagram, there are three Light Dependent Resistors (LDRs)
which are placed on a common plate with solar panel. Light from a source strikes
on them by different amounts. Due to their inherent property of decreasing
resistance with increasing incident light intensity, i.e. photoconductivity, the value
of resistances of all the LDRs is not always same.
Each LDR sends equivalent signal of their respective resistance value to the
Microcontroller which is configured by required programming logic. The values
are compared with each other by considering a particular LDR value as reference.
One of the two dc servo motors is mechanically attached with the driving axle of
the other one so that the former will move with rotation of the axle of latter one.
The axle of the former servo motor is used to drive a solar panel. These two-servo
motors are arranged in such a way that the solar panel can move along X-axis as
well as Y-axis.
The microcontroller sends appropriate signals to the servo motors based on the
input signals received from the LDRs. One servo motor is used for tracking along
x-axis and the other is for y-axis tracking.

In this way the solar tracking system is designed.

20
 2.3 ARDUINO UNO
The Arduino Uno is a microcontroller board based on the ATmega328. Arduino is
an open source, prototyping platform and its simplicity makes it ideal for hobbyists
to use as well as professionals. The Arduino Uno has 14 digital input/output pins
(of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal
oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It
contains everything needed to support the microcontroller; simply connect it to a
computer with a USB cable or power it with an AC-to DC adapter or battery to get
started.

The Arduino Uno differs from all preceding boards in that it does not use the FTDI
USB-to serial driver chip. Instead, it features the Atmega8U2 microcontroller chip
programmed as a USB-to-serial converter.

"Uno" means one in Italian and is named to mark the upcoming release of Arduino
The Arduino Uno and version 1.0 will be the reference versions of Arduino,
moving forward. The Uno is the latest in a series of USB Arduino boards, and the
reference model for the Arduino platform.

FIG 2.2 :- ARDUINO UNO

21
2.4 PIN DIAGRAM OF ARDUINO UNO

FIG 2.3 :- PIN DIAGRAM

22
 2.5 LDR (Light Dependent Resistor)
 It is a photo-resistor is a device whose resistivity is a function of the
incident electromagnetic radiation. Hence, they are light sensitive
devices. They are also called as photo conductors, photo conductive
cells or simply photocells.
 They are made up of semiconductor materials having high resistance.
 LDR works on the principle of photo conductivity.

Photo conductivity is an optical phenomenon in which the material’s

conductivity is increased when light is absorbed by the material.

The most common type of LDR has a resistance that falls with an increase in
the light intensity falling upon the device (as shown in the image above). The
resistance of an LDR may typically have the following resistances:

Daylight = 5000Ω

Dark = 20000000Ω

FIG 2.4 :- Light Dependent Resistor

23
 Therefore, it is seen that there is a large variation between these figures. If
this variation is plotted on a graph, something similar to the figure given
below can be seen.

FIG 2.5 :- INTENSITY GRAPH OF LDR

24
2.6 SERVO MOTOR

A DC servo motor consists of a small DC motor, feedback potentiometer, gearbox,

motor drive electronic circuit and electronic feedback control loop. It is more or
less similar to the normal DC motor.
The stator of the motor consists of a cylindrical frame and the magnet is attached
to the inside of the frame.
A brush is built with an armature coil that supplies the current to the commutator.
At the back of the shaft, a detector is built into the rotor in order to detect the
rotation speed. With this construction, it is simple to design a controller using
simple circuitry because the torque is proportional to the amount of current flow
through the armature.

FIG 2.6 :- SERVO MOTOR

25
 2.7 H-BRIDGE
An H-bridge is a simple circuit that lets you control a DC motor to go backward or
forward .You normally use it with a microcontroller, such as an Arduino, to control
motors .When you can control two motors to go either forward or backward – you
can build yourself a robot

Here’s the concept of the H-bridge:

FIG 2.7 :- H-BRIDGE

26
A DC motor spins either backward or forward, depending on how you connect the
plus and the minus.

If you close switch 1 and 4, you have plus connected to the left side of the motor and
minus to the other side. And the motor will start spinning in one direction .

If you instead close switch 2 and 3, you have plus connected to the right side and
minus to the left side. And the motor spins in the opposite direction.

27
2.8 RESISTOR
It is an electrical device may be a passive two-terminal
electrical part that implements resistance as a circuit
component. In electronic circuits, resistors unit of
measurement accustomed reduce current flow, alter signal
levels, to divide voltages, bias active components, and
terminate transmission lines, among completely different
uses.

FIG 2.8 :- RESISTOR

28
 2.9 BATTERY CAP
A battery assembled cap, a cylindrical battery with the cap and a
method for making the same. The vent cap is attached to the
battery cover by a hinge connection which allows for play
between the vent cap and the battery cover and which allows for
rotation of the vent cap.

FIG 2.9 :- BATTERY CAP

2.10 BATTERY

An electric battery is a device consisting of one or more electrochemical

cells with external connections provided to power electrical devices
such as flashlights, and electric cars.

FIG 2.10 BATTERY

29
When a battery is supplying electric power, its positive terminal is the
cathode and its negative terminal is the anode. The terminal marked
negative is the source of electrons that will flow through an external
electric circuit to the positive terminal. When a battery is connected to
an external electric load.

2.11 SWITCH
A switch, in the context of networking is a high-speed device that
receives incoming data packets and redirects them to their destination
on a local area network (LAN). A LAN switch operates at the data link
layer (Layer 2) or the network layer of the OSI Model and, as such it can
support all types of packet protocol

FIG 2.11 :- SWITCH

30
CHAPTER 3
SOFTWARE PROGRAM MODEL
3.1 PROGRAMING CODE
#include <Servo.h>

Servo horizontal; // horizontal servo

int servoh = 170;
int servohLimitHigh = 170;
int servohLimitLow = 20;
// 65 degrees MAX

Servo vertical; // vertical servo

int servov = 45;
int servovLimitHigh = 140;
int servovLimitLow = 40;

// LDR pin connections

// name = analogpin;
int ldrlt = A1; //LDR top left - BOTTOM LEFT <--- BDG
int ldrrt = A3; //LDR top rigt - BOTTOM RIGHT

int ldrld = A0; //LDR down left - TOP LEFT

int ldrrd = A2; //ldr down rigt - TOP RIGHT

void setup(){
horizontal.attach(3);
vertical.attach(2);
horizontal.write(120);
vertical.write(70);
delay(2500);
}
void loop() {
int lt = analogRead(ldrlt); // top left
int rt = analogRead(ldrrt); // top right
31
 int ld = analogRead(ldrld); // down left
int rd = analogRead(ldrrd); // down right
int dtime = 10; int tol = 90; // dtime=diffirence time, tol=toleransi
int avt = (lt + rt) / 2; // average value top
int avd = (ld + rd) / 2; // average value down
int avl = (lt + ld) / 2; // average value left
int avr = (rt + rd) / 2; // average value right
int dvert = avt - avd; // check the diffirence of up and down
int dhoriz = avl - avr;// check the diffirence og left and rigt

if (-1*tol > dvert || dvert > tol)

{
if (avt > avd)
{
servov = ++servov;
if (servov > servovLimitHigh)
{servov = servovLimitHigh;}
}
else if (avt < avd)
{servov= --servov;
if (servov < servovLimitLow)
{ servov = servovLimitLow;}
}
vertical.write(servov);
}
if (-1*tol > dhoriz || dhoriz > tol) // check if the diffirence is in the tolerance else
change horizontal angle
{
if (avl > avr)
{
servoh = --servoh;
if (servoh < servohLimitLow)
{
servoh = servohLimitLow;
}
}
else if (avl < avr)
{
servoh = ++servoh;
32
if (servoh > servohLimitHigh)
{
servoh = servohLimitHigh;
}
}
else if (avl = avr)
{
delay(5000);
}
horizontal.write(servoh);
}

delay(dtime);

FIG 3.1 :- CIRCUIT DIAGRAM

33
3.2 DESCRIPTION OF THE SOFTWARE PROGRAM

STEPS

 First of all, both the servos are declared and object is created to control the
servo motors.
 The variables posx and posy are used to store the reference servo positions.
 The ADC input pins for LDRs are selected for dual direction movement and
one for reference. A tolerance or a constant value is selected to establish the
working of the motors.
 The servos are attached on digital pins to the servo object. • The required
analog pins are selected as input using pin Mode(pin , mode)
 The servos are sets to mid-point or original position with a 1000ms or 1sec
delay to catch up with the user.
 Three variables are chosen to read the analog values and map it into integers
value between 0 and 1023.
 If the difference between the two variables is less than the tolerance value then
it will stays to its or original location else it shows movement towards the
direction of maximum intensity of light by incrementing or decrementing the
values of posx and posy.
 The position is then written to servo and the loop repeats till it encounter any
changes in the values of input greater than the minimum tolerance.
 •If the position becomes greater than 150˚then position will be set to 150˚only
and if the position of the motor is less than 30˚then it would be kept at 30˚only
as the lower and upper limit angles are chosen to be 30˚and 150˚respectively

34
CHAPTER 4
DISCUSSION AND CONCLUSION

4.1 ABOUT SOLAR PANEL AND CONNECTED LOAD

 Solar panel is placed at the top and connected to a load directly. The
load may a led or a voltmeter which could be connected to get the
exact voltage which depends on the intensity of light falling on the
panel and the position of the tracker.

 Concentrated solar photovoltaic’s’ and have optics that directly accept

sunlight, so solar trackers must be angled correctly to collect energy.
All concentrated solar systems have trackers because the systems do
not produce energy unless directed correctly toward the sun.

 The solar panel is just a mere device to accept the light radiation
which is purely controlled by LDR sensors and the load connected
depends upon the rating of the panel used.

FIG 3.2 :- DUAL AXIS SOLAR TRACKER MODEL

35
4.2 DUAL AXIS MOVEMENT OF SOLAR TRACKER

 The dual axis solar tracker is device which senses the light and
positions towards the maximum intensity of light. It is made in
such a way to track the light coming from any direction.
 To simulate the general scenario of the Sun’s movement, the total
coverage of the movement of the tracker is considered as 120˚ in
both the directions.
 The initial position of both the servo motors are chosen at 90˚i.e,
for east-west servo motor as well as for north-south servo motor.
 The position of the tracker ascends or descends only when the
threshold value is above the tolerance limit.

36
 4.3 BENEFITS AND DEMERITS OF SOLAR ENERGY

There are several benefits that solar energy has and which make
it favourable for many uses.

Benefits:
 Solar energy is a clean and renewable energy source.
 Once a solar panel is installed, the energy is produced at reduced
costs.
 Whereas the reserves of oil of the world are estimated to be
depleted in future, solar energy will last forever.
 It is pollution free.
 Solar cells are free of any noise. On the other hand, various
machines used for pumping oil or for power generation are noisy.
 Once solar cells have been installed and running, minimal
maintenance is required. Some solar panels have no moving parts,
making them to last even longer with no maintenance.
 On average, it is possible to have a high return on investment
because of the free energy solar panels produce.
 Solar energy can be used in very remote areas where extension of
the electricity power grid is costly.

Demerits:
 Solar panels can be costly to install resulting in a time lag of many
years for savings on energy bills to match initial investments.
37
 Generation of electricity from solar is dependent on the country’s
exposure to sunlight. That means some countries are slightly
disadvantaged.
 Solar power stations do not match the power output of conventional
power stations of similar size. Furthermore, they may be expensive
to build.
 Solar power is used for charging large batteries so that solar
powered devices can be used in the night. The batteries used can be
large and heavy, taking up plenty of space and needing frequent
replacement.

FINALLY,
As the merits are more than the demerits, the use of solar power is
considered as a clean and viable source of energy. The various
limitations can be reduced through various ways.

38
 4.4 OBSERVATIONS AND RESULT

WHAT WE HAVE OBSERVED.... In this Dual Axis Solar

Tracker, when source light falls on the panel, the panel adjusts its
position according to maximum intensity of light falling perpendicular
to it.
The objective of the project is completed. This was achieved through
using light sensors that are able to detect the amount of sunlight that
reaches the solar panel. The values obtained by the LDRs are compared
and if there is any significant difference, there is actuation of the panel
using a servo motor to the point where it is almost perpendicular to the
rays of the sun.
This was achieved using a system with three stages or sub systems.
Each stage has its own role. The stages were;

 An input stage that was responsible for converting incident light

to a voltage.
 A control stage that was responsible for controlling actuation and
decision making.
 A driver stage with the servo motor. It was responsible for actual
movement of the panel.
The input stage is designed with a voltage divider circuit so that
it gives desired range of illumination for bright illumination
conditions or when there is dim lighting. The potentiometer was
adjusted to cater for such changes. The LDRs were found to be
most suitable for this project because their resistance varies with
39
light. They are readily available and are cost effective.
Temperature sensors for instance would be costly.
The control stage has a microcontroller that receives voltages
from the LDRs and determines the action to be performed. The
microcontroller is programmed to ensure it sends a signal to the
servo motor that moves in accordance with the generated error.
The final stage was the driving circuitry that consisted mainly of
the servo motor. The servo motor had enough torque to drive the
panel. Servo motors are noise free and are affordable, making
them the best choice for the project.

40
4.5 CONCLUSION
In this 21st century, as we build up our technology, population &
growth, the energy consumption per capita increases
exponentially, as well as our energy resources (e.g. fossils fuels)
decrease rapidly. So, for sustainable development, we have to
think alternative methods (utilization of renewable energy
sources) in order to fulfill our energy demand.
In this project, Dual Axis Solar Tracker, we’ve developed a
demo model of solar tracker to track the maximum intensity
point of light source so that the voltage given at that point by the
solar panel is maximum. After a lot of trial and errors we’ve
successfully completed our project and we are proud to invest
some effort for our society. Now, like every other experiment,
this project has couple of imperfections.
(i) Our panel senses the light in a sensing zone, beyond
which it fails to respond.
(ii) If multiple sources of light (i.e. diffused light source)
appear on panel, it calculates the vector sum of light
sources & moves the panel in that point.
This project was implemented with minimal resources. The
circuitry was kept simple, understandable and user friendly.

41
APPENDX
SPECIFICATIONS OF THE HARDWARE
REQUIREMENT

FEATURES OF ARDUINO UNO

Microcontroller: ATMEGA 328P
The Atmel®picoPower®ATmega328/P is a low-power
CMOS 8-bitmicrocontroller based on the AVR® enhanced
RISC architecture.

FEATURES
High Performance, Low Power Atmel®AVR® 8-Bit
Microcontroller Family
• Advanced RISC Architecture
– 131 Powerful Instructions
– Most Single Clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 20 MIPS Throughput at 20MHz
– On-chip 2-cycle Multiplier
• High Endurance Non-volatile Memory Segments
– 32KBytes of In-System Self-Programmable Flash program
Memory
– 1KBytes EEPROM
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– 2KBytes Internal SRAM
– Write/Erase Cycles: 10,000 Flash/100,000 EEPROM
– Data Retention: 20 years at 85°C/100 years at 25°C(1)
– Optional Boot Code Section with Independent Lock Bits
• In-System Programming by On-chip Boot Program
• True Read-While-Write Operation
– Programming Lock for Software Security
2) Operating Voltage: 5v
3) Input Voltage (recommended): 7-12V
4) Input Voltage (limits): 6-20V
5) Digital I/O Pins: 14 (of which 6 provide PWM output)
6) Analog Input Pins: 6
7) DC Current per I/O Pin: 40 mA
8) DC Current for 3.3V Pin: 50 Ma
9) Flash Memory: 32 KB of which 0.5 KB used by boot loader
10)SRAM: 2 KB (ATmega328)
11)EEPROM: 1 KB (ATmega328)
12)Clock Speed: 16 MHz

SOLAR PANEL
1) Maximum Voltage: 6volts (under load)
2) Maximum Voltage: 6.8volts (no load)
3) Rated Current: 550mA
4) Dimension: 6 cm (L) x 6 cm (W) x 0.25 cm (t)
5) Maximum Wattage: 0.5W

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 SERVO MOTOR
MODULATION ANALOG
Torque 6.8V :3.17 kg-cm
6.0V :4.10 kg-cm
Speed 6.8V :0.23 sec/60°
6.0V :0.19 sec/60°
Weight 37.2g
Dimension 39.9mm x 20.1mm x 36.1 mm
Motor type 3 pole Ferrite
Gear type Plastic
Rotation/Support Bushing
Operation angle 45 Deg.one side pulse travelling
400 µs
Pulse cycle 30 ms
Pulse width 500-300 µs
Connector type J

LIGHT DEPENDENT RESISTOR

Photoresistor 5mm GL5516 LDR Photo Resistors Light-Dependent Resistor
Model: GL5516
 Size: 5mm x 2mm
 Maximum Voltage: 150 Volt DC
 Maximum Wattage: 90mW
 Operating Temperature: (-30 to +70)°C
 Spectral Peak: 540nm
 Light Resistance (at 10 Lux): 5-10 kΩ
 Dark Resistance: 0.5 MΩ
 Response time: 20ms (Rise), 30ms (Dow)

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AVENUES FOR FURTHER WORK
With the available time and resources, the objective of the
project was met. The project is able to be implemented on a
much larger scale. For future projects, one may consider the use
of more efficient sensors, which should also be cost effective
and consume little power. This would further enhance efficiency
while reducing costs. If there is the possibility of further
reducing the cost of this project, it would help a great deal. This
is because whether or not such projects are embraced is
dependent on how cheap they can be. Shading has adverse
effects on the operation of solar panels. Shading of a single cell
will have an effect on the entire panel because the cells are
usually connected in series. With shading therefore, the tracking
system will not be able to improve efficiency as is require

45
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