SIM UNIVERSITY
SCHOOL OF SCIENCE AND TECHNOLOGY
AUTOMATIC SOLAR TRACKER
STUDENT
: TEO AI WEI, Z0706294
SUPERVISOR : MR CHANDRAN AYYANARAPPAN
PROJECT CODE: JAN2010/ENG/0035
Bachelor of Engineering Electronics
November 2010
ACKNOWLEDGEMENT
ACKNOWLEDGEMENT
I would like to express my deepest appreciation and gratitude to my project supervisor, Mr.
Chandran for his advice and guidance throughout the project. He has provided me valuable
direction and suggestions during the course of this project. I would also like to express my
appreciation to my classmates who have given me ideas on how to design the solar tracker.
I
ABSTRACT
ABSTRACT
An automatic solar tracking system was designed and constructed in this project. It is
typically installed onto the solar panels to achieve the best alignment with the sun in order to
optimize the trapping of the sun’s solar energy. Such non-polluted and renewable resource is
becoming an important source of energy to generate electricity by using solar cells (also
called photovoltaic) in recent years. In this project, the designed system is made up of LDR
sensors, LM555 timer, stepper motor and motor driver with control circuitry that integrate the
East, West and Dawn circuitry to allow the tracker to rotate in East-West direction and vice
versa. All these components used in the system are easily obtainable and inexpensive. Single
axis tracking method used in this automatic solar tracking system is also relatively efficient to
use. A systematic working approach that included literature study together with varieties of
phases such as design, experimental, development of prototype and testing are being
illustrated in this report. A couple of foreseen and unforeseen issues that manifested up
during this project are highlighted together with the resolving of these problems through good
problem solving process are demonstrated which serve as a beneficial learning experience
throughout this project.
II
TABLE OF CONTENTS
TABLE OF CONTENTS
ACKNOWLEDGEMENTS
I
ABSTRACT
II
TABLE OF CONTENTS
III
LISTS OF FIGURES
V
LIST OF TABLES
VII
LIST OF SYMBOLS
VII
CHAPTER 1: INTRODUCTION………………………………………………………. 01
1.1
Background………………………………………………………………………. 01
1.2
Project Objective…………………………………………………………………. 02
1.3
Project Scope……………………………………………………………………... 02
1.4
Project Schedule………………………………………………………………….. 03
1.5
Report Organization……………………………………………………………… 04
CHAPTER 2: TECHNICAL LITERATURE REVIEW…………………………….... 05
2.1
Solar Panel………………………………………………………………………... 05
2.2
Solar Tracker…………………………………………………………………….... 06
2.2.1
Methods of Tracker Mount……………………………………………….. 09
2.2.2
Sensor Circuitry…………………………………………………………... 10
2.2.3
Motor and Motor Controller……………………………………………… 13
CHAPTER 3: METHODOLOGIES…………………………………………………… 18
3.1
System concept…………………………………………………………………… 18
3.2
Hardware selection……………………………………………………………….. 18
3.2.1
Sensor…………………………………………………………………….. 18
3.2.2
Motor……………………………………………………………………... 20
3.2.3
Miscellaneous components………………………………………………. 22
CHAPTER 4: DESIGN OVERVIEW…………………………………………………. 24
4.1
Design Concept…………………………………………………………………… 24
4.2
Design of Sensor circuitry and LM555 timer…………………………………….. 27
4.3
Design of Voltage regulator………………………………………………………. 30
4.4
Design of Stepper motor driver…………………………………………………… 30
III
TABLE OF CONTENTS
CHAPTER 5: CIRCUITRY EXPERIMENTAL PHASE…………………………….. 32
5.1
Overview………………………………………………………………………….. 32
5.2
Dawn Circuitry……………………………………………………………………. 32
5.3
East Circuitry……………………………………………………………………... 36
5.4
Motor Driver circuitry……………………………………………………………. 37
5.5
Motor Driver circuitry with motor………………………………………………... 40
5.6
Integration of East, West and Dawn circuitry with Motor driver and motor……... 42
CHAPTER 6: DEVELOPMENT PHASE……………………………………………… 45
6.1
PCB design………………………………………………………………………... 45
6.2
Circuit Board Development ……………………………………………………… 47
6.3
Hardware implementation………………………………………………………… 48
CHAPTER 7: PROBLEMS AND SOLUTIONS..…………………………………….. 49
7.1
Problems encountered…………………………………………………………….. 49
7.2
Solutions…………………………………………………………………………... 50
CHAPTER 8: CONCLUSION AND RECOMMENDATION………….…………….. 51
8.1
Conclusion………………………………………………………………………… 51
8.2
Recommendation………………………………………………………………….. 52
CHAPTER 9: REVIEW AND REFLECTION………….………………….…………. 53
REFERENCES…………………………………………………………………………... 55
APPENDIX………………………………………………………………………………. 57
Appendix A: Schematics Diagram and Gantt Chart
A1: Automatic Solar tracker Schematic Design
A2: Automatic Solar tracker PCB Design
A3: Initial Gantt Chart
A4: Revised Gantt Chart
Appendix B: Datasheet
B1: LM555 timer
B2: Exclusive-OR Gate
B3: D-Type Flip Flop
B4: LM7812 Voltage Regulator
B5: CdS Photocell (LDR)
B6: PNP Transistor
IV
TABLE OF CONTENTS
LIST OF FIGURES
Figure 2.1.1: Illustration on how internal solar cell works
Figure 2.1.2: Diagram of a Solar Energy operation
Figure 2.2.1: Fixed solar panel
Figure 2.2.2: Foldable solar panel
Figure 2.2.3: Programmable solar panel
Figure 2.2.4: Dynamic tracking tracker
Figure 2.2.5: Block diagram to illustrate how solar tracker function
Figure 2.2.1.1: Single Axis Solar Tracker
Figure 2.2.1.2: Dual Axis Tracking System
Figure 2.2.2.1: Example of Photodiode
Figure 2.2.2.2: Example of Phototransistor
Figure 2.2.2.3: Example of actual LDR and its symbols
Figure 2.2.2.4: Example of Photovoltaic Solar Cell
Figure 2.2.3.1: DC motor and its operation
Figure 2.2.3.2: Servo Motor
Figure 2.2.3.3: Stepper Motor
Figure 2.2.3.4: Permanent-Magnet stepper motor
Figure 2.2.3.5: Unipolar and Bipolar Comparison
Figure 3.2.1: Solar Tracker Design
Figure 3.2.1.1: LDR Type A
Figure 3.2.1.2: LDR Type B
Figure 3.2.2.1: Example of how stepper motor turns
Figure 3.2.3.1: LM555 timer Astable circuitry
Figure 3.2.3.2: Stepper motor Full Step Drive
Figure 3.2.3.3: 2-phase Excitation Signal time chart
Figure 3.2.3.4: Stepper Motor Driver Circuit
Figure 4.1.1: Drawn diagrams to illustrate the different views of the sensor board
Figure 4.1.2: Drawn diagram to illustrate the East LDR that detected sunlight
Figure 4.1.3: Drawn diagram to illustrate the Dawn LDR that detected sunlight
Figure 4.1.4: Flowchart showing the overview of the Solar Tracker
Figure 4.2.1: Diagram showing the circuitry of Type A and B
V
TABLE OF CONTENTS
Figure 4.2.2: Drawn diagram showing the schematic of the sensor circuitry
Figure 4.2.3: East/ West Circuitry Schematic
Figure 4.3.1: Fixed output voltage regulator
Figure 4.4.1: Diagram showing the Motor Driver Circuitry
Figure 5.2.1: Photographs showing the voltage regulator and dawn circuitry
Figure 5.2.2: Output is at high when no light on LDR
Figure 5.2.3: Output observed RB = 100kΩ and RL = 20kΩ
Figure 5.2.4: Output observed RB = 100kΩ and RL = 10kΩ
Figure 5.2.5: Output observed RB = 100kΩ and RL = 3.5kΩ
Figure 5.2.6: Output observed RB = 50kΩ and RL = 20kΩ
Figure 5.2.7: Output observed RB = 15kΩ and RL = 20kΩ
Figure 5.3.1: East circuitry used for testing
Figure 5.4.1: Drawn diagram and photograph showing the motor driver
Figure 5.4.2: Output Waveforms of D flip flop
Figure 5.4.3: Output Waveforms of Motor Driver (XOR pin 1 set to VCC or GND)
Figure 5.4.4: Motor Driver Circuitry and overall circuit
Figure 5.5.1: PNP transistor as a switch (ON mode and OFF mode)
Figure 5.6.1: Overall Schematic Design
Figure 6.1.1: Overall view of the PCB Design Layout
Figure 6.1.2: 3D design translated by “Easy PC” software
Figure 6.1.3: Diagrams showing the PCB design in top, side and bottom views
Figure 6.2.1: An overview of the Initial Circuit board (Top and Bottom views)
Figure 6.2.2: An overview of the Finalized Circuit Board (Top and Bottom views)
Figure 6.2.3: Sensor Board
Figure 6.2.4: Solar tracker
VI
TABLE OF CONTENTS
LIST OF TABLES
Table 1.4.1: Initial Gantt chart
Table 1.4.2: Revised Gantt chart
Table 2.2.1: Solar Energy collection methods
Table 3.2.1.1: LDR measured resistance
Table 5.2.1: Measured frequency under different RB and
Table 5.6.1: Truth Table
Table 5.6.2: Karnaugh map
LIST OF SYMBOLS
Ω – ohms
Hz – Hertz
LDR – Light Dependant Resistor
DC – Direct current
XOR – Exclusive OR
T – Time Period
f – Frequency
C – Capacitor
F – Farad
A – Ampere
ms/div – milliseconds/ division
VII
RL setting
INTRODUCTION
CHAPTER 1: INTRODUCTION
1.1
Background
Over the recent years, greenhouse effect has resulted in global warming and caused
unpredictable climate changes. It is manifested that mankind, who has to pay
enormous prices in their daily life due to all these drastic weather change. In an
attempt to fight against the continual global warming and reduce its impact, many
national governments have signed and endorsed the Kyoto Protocol. Such move is
necessary to increase environmental awareness and educated people that all current
energy sources are limited and in high demand. Renewable energy systems are
becoming popular in which it comes from natural resources such as sunlight, wind,
rain, tides, and geothermal heat [1] .
This project focus on efficient methods to obtain solar energy source that can converts
into electricity. Basically, solar energy is a non-polluting and renewable resource that
required very little maintenance. Even though solar panels and their accessories (solar
lights, etc.) may be expensive to buy at the onset, money is saved in the long run since
the abundant energy from the sun is widely available and free. In order to maximize
power output from the solar panels, one needs to keep the panels to be aligned with
the sun. Therefore, solar tracker is required. This will be a more cost effective
solution than purchasing more panels.
The aim of this project is to develop an automatic solar tracker which will keep the
solar panel aligned with the sun to achieve maximum efficiency. A solar tracker traces
and focuses on the sunlight as the sun move across the sky with position varies during
different season period and different time of the day. Since sunlight produces solar
power where it generates electricity with solar powered devices works best when sun
is directly pointed at them, the ability of an automatic solar tracker that tracks the
solar energy accurately throughout the day will definitely help to increase the
effectiveness of these power devices over any fixed position.
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INTRODUCTION
1.2
Project Objective
This project aims to design and develop an inexpensive and accurate automatic solar
tracker basically using only electronics components. It also provides an opportunity to
apply the knowledge of electronics module to design a prototype of a product.
1.3
Project Scope
In order to ensure the development of the automatic solar tracker to be successful, a
well-structured and systematic plan has to be carried out throughout the project by
engaging in detailed research with careful execution during design and test phase that
will ultimately transform the assembly of the components into a working prototype.
Research and Design of Solar Tracker

Background study and literature review

Discussion on Ideas and Concepts

Technical Design and Modeling

Testing and Evaluation of Ideas

Solar Tracker Design Implementation
Hardware Development

Components selection and Circuit Simulation

Design Implementation

Testing and Troubleshooting

Modifications and Improvements
Presentation

Final Report writing

Poster Presentation
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INTRODUCTION
1.4
Project Schedule
In order to successfully develop the solar tracker, proper planning is necessary for
achieving the project goals and objectives. A Gantt chart shown in Table 1.4.1 is
created in the early phase of the project to help in keeping track of the progress and
timeline in a more systematic way. Throughout the project, additional tasks are
required and the revised Gantt chart is shown in Table 1.4.2.
Table 1.4.1: Initial Gantt chart
Legend:
Planned
Actual
Table 1.4.2: Revised Gantt chart
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INTRODUCTION
1.5
Report Organization
Chapter 1: This chapter includes the introduction and objective of the project.
Chapter 2: Project study and literature review was carried out on solar tracker in
terms of the methods of tracking system, motor and sensor circuitry.
Chapter 3: Discussion on system concept and selected components.
Chapter 4: This chapter explains the overview and every portion of the solar tracker
design.
Chapter 5: The chapter shows how the experimental is conducted by building on
breadboard design, various testing and troubleshooting.
Chapter 6: Development phase showing schematic, PCB design and the hardware
implementation.
Chapter 7: This chapter shows the problems encountered and suggested solutions.
Chapter 8: Conclusion and Recommendation.
Chapter 9: Review and Reflection.
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LITERATURE REVIEW
CHAPTER 2: TECHNICAL LITERATURE REVIEW
2.1
Solar Panel
A solar cell is a device that absorbs and converts the energy of sunlight directly into
electricity by the photovoltaic effect. Solar panels are formed from a packaged
interconnected assembly of these solar cells to capture the sunlight. The photons in
sunlight that hit the solar panels are then absorbed by semiconductor materials such as
Silicon (Si) and create current flow in one direction from the interaction of photons
with the atoms in Si material.
Figure 2.1.1: Illustration on how internal solar cell works [ 2 ]
Figure 2.1.2: Diagram of a Solar Energy operation [ 3]
Applications of Solar Cells
Solar cell devices have been used in variety of products namely:

Small consumer items such as calculator or rechargeable battery

Large commercial solar electric systems

Power spacecrafts and satellites' electrical systems
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LITERATURE REVIEW
2.2
Solar Tracker
In order to stay competitive with other different green energies as well as to refrain
from losing present and new market shares on this global marketplace, it is critical to
ensure the electricity produced by using solar cells to be effective with maximum
output. This can be achieved from either of the two proposed ways, namely
1) Developing the solar cell material and making the panels even more efficient.
2) Optimizing the output by installing the solar panels on a tracking base that follows
the sun.
Based on various surveys conducted, generally, the end-users prefer more to tracking
system solution rather than a fixed ground system as a way to increase their earnings.
Investment in the automatic solar tracking system will yield a definite good return and
concurrently, contributed greatly to the welfare of human in reducing greenhouse
effect while achieving a continual abundant energy supplies. It has been estimated
that the yield from solar panels can be increased by 30 to 60 percent by utilizing a
tracking system instead of a stationary array [ 4 ] .
There are few methods of collecting solar energy in which the first three listed
methods in the table are typically inefficient.
Table 2.2.1: Solar Energy collection methods
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LITERATURE REVIEW
Figure 2.2.1: Fixed solar panel
[5]
Figure 2.2.2: Foldable solar panel
[6]
Figure 2.2.3: Programmable solar panel
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[7]
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LITERATURE REVIEW
The best method is to use a dynamic tracking system to automatically track the sun
position any time of the day and control the solar panel to point to the optimal solar
energy collection position (Active tracking). Automatic Solar tracker is a dynamic
tracking system that is introduced in order to increase the efficiency of the solar cells.
Figure 2.2.4: Dynamic tracking tracker
[8]
The components to build a solar tracker are motor, light sensor, solar cell, controller,
power supply and some electronics components.
Figure 2.2.5: Block diagram to illustrate how solar tracker function
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LITERATURE REVIEW
The design and construction of it could be divided into three main parts, each with
their main function. They are:
1. Tracking System
2. Sensor Circuitry
3. Motor Circuitry
The following sections present background information on the main subsystems of the
project. Specifically, this section discusses on the tracking methods, sensors and
motor theory in order to provide a better understanding as to how they relate to the
solar tracker.
2.2.1
Methods of Tracker Mount
A solar tracking system is a device for orienting a solar panel or concentrating
a solar reflector or lens towards the sun [ 9 ] . A tracker can increase the
effectiveness of such system over any fixed position and is perfect to use with
solar panels for maximum efficiency of your system.
Generally, the two most common methods of active solar tracking system are
the single-axis tracker and dual-axis tracker. A single axis tracker increases the
annual output by a minimum of 30%, and a dual axis tracker increases it by an
additional 6% [10] . A single-axis tracker can either have a horizontal or vertical
axle while double-axis tracker has both axles to track the sun’s apparent
motion.
Single axis tracker uses one motor controlled by a controller to track the
movement of the sun. It moves in a single path normally from the East to the
West and vice versa. This is the simplest solution and the most common one
used.
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LITERATURE REVIEW
Figure 2.2.1.1: Single Axis Solar Tracker
[9]
Dual axis tracker uses two motors controlled by a controller to track the
movement of the sun. It moves in all direction in azimuth axis and in elevation
axis. Dual Axis tracking system is more efficient and precise than Single Axis
tracking system as it moves all directions to achieve maximum solar energy
but it involves complex mathematical algorithm with complex design and
more costly.
Figure 2.2.1.2: Dual Axis Tracking System
2.2.2
[9]
Sensor Circuitry
In solar tracker, light sensor is used to detect and measure the light energy
from the surrounding. The measured data was feedback to the controller that
analyzes the input and operates the solar tracker by moving it to find the
optimal solar energy direction. There are a few common types of light sensor
as shown below.
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LITERATURE REVIEW
Photodiode is a PN Junction diode with the outer casing that is transparent so
that light can fall upon the junction. When light falls onto the junction, it
generates current or voltage depending on the mode of operation. Although
photodiode has very fast response, the current flow in it is relatively small
even when fully lit. Photodiodes are commonly used in cameras, fiber optics
and TV type remote controls, etc.
Figure 2.2.2.1: Example of Photodiode
[11]
Phototransistor is basically a photodiode with amplification. It is a NPN
transistor and is more sensitive than photodiode. The output current produced
by the phototransistor is 50 - 100 times greater than that of a standard
photodiode. However, it does not have a good high frequency response. It is
commonly used as opto-isolator and light beam sensors, etc.
Figure 2.2.2.2: Example of Phototransistor
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[11]
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LITERATURE REVIEW
LDR (Light Dependant Resistor), which is also known as "CdS Photo cells",
is simply a resistor that changes its electrical resistance when light intensity
changes. When the light shines onto it, the resistance value drops and allows
current to pass through it. However, when the light level drops, the resistance
value become higher and this prevents current from flowing to the base of the
transistors
[12]
. LDR are small, inexpensive and low-power. They are easy to
use and don’t wear out easily. LDR is commonly used as ORP12 Cadmium
Sulphide photoconductive cell, camera light meters, street lights, clock radios,
alarm and outdoor clocks
type of light sensor
[14]
[13]
. This is the least expensive and least complex
.
Figure 2.2.2.3: Example of actual LDR and its symbols [11]
Photovoltaic Cell is the most common light sensor used in Solar cell. It can
be used to measure the light intensity or converts the light energy directly into
electrical energy in the form of current or voltage. Photovoltaic cells convert
sunlight into DC current and, at present, are about 30% efficient
[19]
and
lifespan is around 25-30 years. Photovoltaic Solar Cell is commonly used on
calculators, watches and rooftop panels while an array of solar cells is
normally used in power satellites.
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LITERATURE REVIEW
Figure 2.2.2.4: Example of Photovoltaic Solar Cell
2.2.3
[16]
Motor and Motor Controller
Motor is one of the most important parts of the automatic solar tracker. It
drives the solar panel at the direction of the sunlight as the sun move across
the sky from east to west and vice versa. Motor selection is critical to ensure
selected battery type is able to drive it. There are mainly 3 choices of motor
system for selection, namely the DC, Servo and Stepper motor.
DC (Direct current) motor works from a direct current supply and it is one
of the simplest motor [17] . This motor consists of permanent magnet coil up
with loops of wires to the stator. It rotates when DC voltage is applied to the
motor and current will flow through from the negative terminal to the positive
terminal through the field coil. Voltage is induced in the windings to oppose
the current flowing in them. However, the speed is not easy to control as it
spins too fast which causes insufficient torque. Therefore, it is necessary to
include a paper encoder wheel, H-bridge circuit and a gearbox as a feedback
system to provide sufficient power and control the speed of the motor. It is
very popular in certain application due to its fast speed
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[18]
.
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LITERATURE REVIEW
Figure 2.2.3.1: DC motor and its operation
[19]
Servo motor is an electromechanical device in which an electrical input
determines the position of the armature of a DC motor. Servos are used
extensively in robotics and radio-controlled toys
[ 20]
. It contains a small
gearbox with a built in control circuitry, DC motor and a potentiometer which
enables a precise motor controlling. With an output shaft, DC servo motor can
be positioned by sending a Pulse coded signal to the motor and it turns when
signal is received.
The amount of power applied is proportional to the amount of distance
required. Therefore, if the shaft requires turning a large distance, the motor
will run at full speed and vice versa. Any wrong timing will result in overtravel or under-travel which could easily causes malfunction. The motor is
able to travel very fast due to the gear ratio and thus requires modification for
continuous rotation together with the shaft encoders [ 21] . DC Servo motor is
popular with its relatively small size and is easy to control but it is rather
expensive.
Figure 2.2.3.2: Servo Motor
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[ 34]
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LITERATURE REVIEW
Stepper motor is similar to a digital motor that moves in steps. It can be
easily controlled in terms of its speed as compared to a DC motor. The
distance travelled can be easily calculated by counting the number of steps
rotated by the motor. The speed and acceleration can be controlled by varying
the delay between the pulse signals which is programmable or using electronic
circuit to produce it. Different type of stepper motor produces different
number of steps. Example about 200/400 steps are required for Stepper
motor’s full 3600 turn. It consists of a rotor, which is a permanent magnet
rotating shaft and a series of coils that create a magnetic field which coiled
around the body of the rotor for movement.
Figure 2.2.3.3: Stepper Motor
[ 23]
There are three types of stepper motor used in the market namely, variable
reluctance, permanent-magnet and hybrid. The most common type is
Permanent-Magnet stepper motor. It has a permanent magnet attached to its
shaft that is called the rotor. Magnetic field interacts with the permanent
magnets, which are cylindrical with multiple N-S poles, through the series of
coils around the body of the motor. There are two energized electro-magnet
and as the stator changes its magnetic field in a certain sequence, the stepper
motor will rotates discretely. Permanent-Magnet stepper motor can be of
Unipolar or Bipolar type.
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LITERATURE REVIEW
Figure 2.2.3.4: Permanent-Magnet stepper motor
[ 22]
Unipolar stepper motor has a rotating permanent magnet surrounded by four
windings and it requires four output lines from the micro-controller to operate.
It contains four separate electromagnets. For motor to turn, current will flow
through each coil one by one in repeating pattern and restart from coil “1”
again. Current is only flowing through the coils in one direction; thus the name
unipolar.
Bipolar stepper motor has two windings instead four, which is more cost
effective than unipolar stepper motor. However, it requires eight output lines
from the micro-controller to operate the 2 H-bridges. The main advantage of
using stepper motor is that there is no feedback needed from the output shafts,
which reduces the time in construction and also less troubleshooting needed.
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LITERATURE REVIEW
Figure 2.2.3.5: Unipolar and Bipolar Comparison
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METHODOLOGIES
CHAPTER 3: METHODOLOGIES
3.1
System concept
After detailed research and advice from the tutor, designing a single axis solar tracker
(bidirectional) is chosen for this project. The overall design framework will be built
with electronics components to control the movement of the solar tracker (with no
programming software included).
From the literature study together with further research, the selected components are
basically easily obtained, inexpensive, suitable and reliable.
3.2
Hardware selection
The Solar Tracker design consists of 3 subsystems as shown in Figure 3.2.1.
Solar
Tracker
Power
Subsystem
Sensor
Subsystem
MotorController
subsystem
Figure 3.2.1: Solar Tracker Design
3.2.1
Sensor
The purpose of sensor subsystem is to detect light and feedback to the
controller subsystem. Light Dependant Resistor (LDR) is selected as sensor in
this project as it is less complex and least expensive.
The resistance of the LDR is inversely proportional to the light intensity.
Figure 3.2.1.1 and 3.2.1.2 show that the LDR is being used as a voltage
divider where output Vout is determined by two resistance (LDR and resistor).
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METHODOLOGIES
Vout increases with an increase in light intensity as LDR is placed near to Vcc
while there is a decrease on the Vout if the LDR is placed near ground since
light intensity increases. In this project, both type A and B are used.
Figure 3.2.1.1: LDR Type A Figure 3.2.1.2: LDR Type B
Table 3.2.1.1: LDR measured resistance
A 20kΩ Trim resistor is chosen for fine tuning with maximum and minimum
values set as 20kΩ and 50Ω respectively. The minimum and maximum
voltages are tabulated as follows:
Assume Vcc is 5V
For Trim resistor at 50 Ω (min),
Min = 5V x (50 Ω/ (50 Ω + 20 MΩ)) ≈ 0V
Max = 5V x (50 Ω/ (50 Ω + 100 Ω)) = 1.67V
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METHODOLOGIES
For Trim resistor at 20 kΩ (max),
Min = 5V x (20kΩ/ (20 kΩ + 20 MΩ)) ≈ 0.005V ≈ 0V
Max = 5V x (20kΩ/ (20 kΩ + 100 Ω)) = 4.97V ≈ 5V
3.2.2
Motor
In literature review, DC motor, servo motor and stepper motor are being
introduced. In this design of solar tracker, servo motor and stepper motor are
being shortlisted as they can achieve better precision.
Stepper motor is very stable and requires no feedback. It is relatively cheaper
with long lifespan and will not be damaged even mechanical overload. Servo
motor is a type of DC motor with built-in controlled circuitry and a
potentiometer. It has high output power with high efficiency and is quieter
than stepper motor when in high speed.
Stepper motor is being selected due to its cheaper cost (few times of servo
motor), much lower power consumption as well as applicable to be used in an
open loop system. The motor is also brushless, load independent, good holding
torque and excellent response characteristics [ 25] .
Unipolar stepper motor is used in this project. Oki KHP35F2001 has an
angular resolution of 0.9/1.8 degrees which produces 200/400 steps for a full
3600 turn. It consists of 6 wires and contains four separate electromagnets (as
shown below). The motor turns when current flows through coil “1” with the
shaft turns a step and stop. This process continues on coil “2”, coil “3” and
coil “4. The whole cycle is then repeated again from coil “1”. The name
unipolar implies that current flows through the coils in one direction only. A 2
phase unipolar driver IC is required to produce the steps to drive the stepper
motor.
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METHODOLOGIES
Figure 3.2.2.1: Example of how stepper motor turns
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METHODOLOGIES
3.2.3
Miscellaneous components
Power Supply: The design requires a 12V to drive the whole circuitry in
which eight 1.5V AA batteries are connected in series. A 12V voltage
regulator is also used to cater for higher power supply and prevent circuit
damage since some ICs chips are sensitive to voltage fluctuations.
Motor Controller Unit: Motor-Controller subsystem comprises of circuitry to
interface with the motor and sensor circuit which is also the “heart” in the
solar tracker. The subsystem consists of LM555 timer that enables the LDR
analogue voltage to convert to digital values. It also consists of a stepper
motor driver that provides 4 digital pulses output to control the Stepper motor
rotation.
LM555 timer generates accurate time delays or oscillation and can be
designed to suit different type of operation such as Monostable, Astable, Pulse
Width Modulator and 50% Duty Cycle Oscillator. In this project, Astable
circuitry is used. The output of the 555 timer will produce pulses whenever the
LDR has detected light.
Figure 3.2.3.1 LM555 timer Astable circuitry
LM555 timer generates single continuous pulse, while a stepper motor
requires four input pulses as shown in figure 3.2.3.2 to drive the motor.
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METHODOLOGIES
Figure 3.2.3.2: Stepper motor Full Step Drive
In order to generate the full step drive, D Flip-Flop and Exclusive OR gate are
integrated together and act as the stepper motor driver. It determines the motor
movement in either clockwise or anti-clockwise through the Excitation signal
time chart in Figure 3.2.3.3. The D Flip-Flop and Exclusive OR gate circuit
are shown in Figure 3.2.3.4.
Clockwise Direction
Anti-Clockwise Direction
Figure 3.2.3.3: 2-phase Excitation Signal time chart
Figure 3.2.3.4: Stepper Motor Driver Circuit
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DESIGN OVERVIEW
CHAPTER 4: DESIGN OVERVIEW
4.1
Design Concept
As mentioned in chapter 3, the key hardware components used in this project
comprised of

Sensor – LDR

LM555 timer

Motor Driver – D flip flop & Exclusive OR gate

Stepper motor model: Oki KHP35F2001
These components will be integrated together with the sensor board and the main
circuitry board to form the solar tracker. The sensor board mainly consists of 5 LDRs
sensors while the main circuitry board is made up of a timer and a motor driver
circuitry.
Top View
Bottom View
Side View
Figure 4.1.1: Drawn diagrams to illustrate the different views of the sensor board
The different views of the sensor board are shown in Figure 4.1.1. The sensor board
resumes the role of the solar panel in which the solar tracker will keep the solar panels
aligned with the sun in order to achieve maximum efficiency.
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DESIGN OVERVIEW
The following 3 scenarios are used to illustrate the function of the sensor board.
Figure 4.1.2: Drawn diagram to illustrate the East LDR that detected sunlight
Scenario 1: Assume that East LDR detected sunlight as shown in Figure 4.1.2, the
light is blocked by the vertical board and thus no light is detected at West LDR.
Motor will rotate clockwise and the sensor board will tilt towards east to align with
the sun. It will stop when both East and West LDRs received same amount of light.
Scenario 2: Similarly, if the West LDRs detects sunlight only, the motor will rotate
anti-clockwise and the sensor board will turn anti-clockwise till both East and West
LDRs are aligned to the light.
Figure 4.1.3: Drawn diagram to illustrate the Dawn LDR that detected sunlight
Scenario 3: Suppose that the sensor board is positioned at the West-side as shown in
Figure 4.1.3 and when the sun rises from the east, Dawn LDR will detect the sunlight
and the motor rotates clockwise direction. The sensor board will turn clockwise
towards East-side and will stop when both East and West LDRs received same
amount of light.
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DESIGN OVERVIEW
The flowchart in Figure 4.1.4 shows an overview of the solar tracker and its
respective functions. More detail description will be discussed in the following
sections.
Figure 4.1.4: Flowchart showing the overview of the Solar Tracker
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DESIGN OVERVIEW
4.2
Design of Sensor circuitry and LM555 timer
Circuit description
There are 2 types of LDR circuitry (Type A and B) connected to LM555 timers as
shown in Figure 4.2.1. The light detected by Type A allows the timer to create pulses
while the timer goes into reset mode for Type B. The timer function converts
analogue LDRs voltage value and output digital values to the motor driver circuitry.
Astable operation is used in this operation.
Type A
Type B
Figure 4.2.1: Diagram showing the circuitry of Type A and B
Figure 4.2.2: Drawn diagram showing the schematic of the sensor circuitry
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DESIGN OVERVIEW
In Astable operation, digital square waveform will be produced. It has sharp transition
between low (0V) and high (+Vcc). The circuit is called Astable operation as it is not
stable in any state with the output continuously changing between Low and High.
The time period (T) of the square wave is the time for one complete cycle. It is split
into two parts, T1 (charge time) and T2 (Discharge time). It is often calculated in
frequency (f) which is the number of cycles per second.
Time period:
T  T1  T2 ;
The charge time (output high):
T1  0.693 * ( RA  RB ) * C ;
The Discharge time (output low):
T2  0.693 * ( RB ) * C ;
Frequency of oscillation:
f 
1
T
Where
RA = 1KΩ + LDR (100Ω (Bright light) to 20MΩ (No light))
RB = 100kΩ Trim Resistor
RL = 20 kΩ Trim Resistor
C = 0.1uF
T = time period in seconds (s)
f = frequency in hertz (Hz)
C = capacitance in farads (F)
RA , RB and RL are resistance in ohms (Ω)
RA and RB are used for speed control of the motor. It produces stream of square
waves at the rate defined by the variable resistor RA and RB .
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DESIGN OVERVIEW
Figure 4.2.3: East/ West Circuitry Schematic
Figure 4.2.3 shows two LDR circuitries that are connected to a 555 timer in Astable
operation. When light shines on the East LDR, the LDR resistance drops and allows
current to flow into pin 7 and resulted the timer to produce output pulses. If more
current flows into pin 7, the output pin 3 will oscillates higher frequency. Timer will
function normally when reset pin 4 is in VCC.
When light shines on East reset LDR, VCC will pass through the LDR and results in
very low or zero voltage which flows into pin 4. This resulted in reset mode and
output pin3 will be 0V. This applies similarly for the West circuitry.
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DESIGN OVERVIEW
4.3
Design of Voltage regulator
Circuit description
Figure 4.3.1: Fixed output voltage regulator
The voltage regulator is designed as shown in Figure 4.3.1. Capacitor C 1 is required
when the regulator is located at a considerable distance away from power supply
filter. Capacitor C0 is used to improve the stability and transient response.
4.4
Design of Stepper motor driver
Circuit description
Figure 4.4.1: Diagram showing the Motor Driver Circuitry
Figure 4.4.1 shows the motor driver circuitry where D flip flop is designed as a
counter. In this design, two counters are used to divide the square waves produced by
the timer. Thus, output of the counter will provide a steady two bit binary code: 00,
01, 10, 11.
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DESIGN OVERVIEW
A two input XOR IC chip comprise of 4 XOR gate is also used in this motor driver
circuitry. It will produce a binary code of 1100, 0110, 0011, 1001 when Pin 1 is set to
VCC and will count backwards when Pin 1 is set to zero volt which resulted in binary
code of 1001, 0011, 0110, 1100.
Motor
Stepper motor model: Oki KHP35F2001 will be used. It is a 12V stepper motor with
resistance of 60 ohms.
Current required to drive the motor = V/I = 12/60 = 0.2A.
As stepper motor step angle is 1.8 deg, it will require 360/1.8 = 200 steps to complete
360 degree to complete a full turn.
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CIRCUITRY EXPERIMENTAL PHASE
CHAPTER 5: CIRCUITRY EXPERIMENTAL PHASE
5.1
Overview
The solar tracker is breakdown into several portions for evaluation before integrating
together.
The breakdown of the circuit is as follows:
1) Dawn circuitry
2) East/ West circuitry
3) Motor driver circuitry
4) Motor Driver circuitry with motor
5) Integration of East, West and Dawn circuitry with motor driver and motor
Kenwood CS4025 and Agilent DSO6014A oscilloscope are used to measure and
capture the output waveforms.
5.2
Dawn Circuitry
During the experimental phase for Dawn circuitry, circuit is implemented on the
breadboard for testing as shown in Figure 5.2.1. A 5V is used as input voltage to all
the ICs chip. A 5V voltage regulator is implemented.
Voltage regulator
Dawn Circuitry
Figure 5.2.1: Photographs showing the voltage regulator and dawn circuitry
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CIRCUITRY EXPERIMENTAL PHASE
This test is used to determine the 555 timer output frequency. The output will be
determined by setting the different values of RL (20KΩ) and RB (100KΩ) when LDR
is under dark or under light situation.
5V
0V
Figure 5.2.2: Output is at high when no light on LDR
Figure 5.2.2 shows the output at 5V when the LDR is covered with a black vinyl tape
to simulate a dark environment.
LDR is under normal light with resistance around 4.7kΩ
a. RB = 100kΩ and RL = 20kΩ with Frequency about 1667Hz (Figure 5.2.3)
0.5ms/div
0.1ms/div
Figure 5.2.3: Output observed with RB = 100kΩ and RL = 20kΩ
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CIRCUITRY EXPERIMENTAL PHASE
b. RB = 100kΩ and RL = 10kΩ with Frequency about 1540Hz (Figure 5.2.4)
0.5ms/div
0.1ms/div
Figure 5.2.4: Output observed with RB = 100kΩ and RL = 10kΩ
c. RB = 100kΩ and RL = 3.5kΩ with Frequency about 1250Hz (Figure 5.2.5)
0.5ms/div
0.1ms/div
Figure 5.2.5: Output observed with RB = 100kΩ and RL = 3.5kΩ
d. RB = 50kΩ and RL = 20kΩ with Frequency about 3500Hz (Figure 5.2.6)
0.5ms/div
0.1ms/div
Figure 5.2.6: Output observed RB = 50kΩ and RL = 20kΩ
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CIRCUITRY EXPERIMENTAL PHASE
e. RB = 15kΩ and RL = 20kΩ with Frequency about 11110Hz (Figure 5.2.7)
50us/div
20us/div
Figure 5.2.7: Output observed with RB = 15kΩ and RL = 20kΩ
Table 5.2.1: Measured frequency under different RB and RL setting
After several testing, it is observed that when the 100k Trim resistor ( RB ) is reduced,
the frequency increases as shown in Table 5.2.1. Also, it is observed that the
frequency decreased when RL value is reduced.
Next experiment is to evaluate the presence of light intensity on the LDR. Results
show that the frequency increases when LDR receives more light and vice versa. It
determines that the stepper motor will move faster when LDR receive more light and
move slower when the light illumination is lesser.
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CIRCUITRY EXPERIMENTAL PHASE
5.3
East Circuitry
This testing is used to determine the output voltage of 555 timer with/without light
shining on the East Reset LDR. East and West circuitry are of the same design.
East LDR
East
Reset
LDR
Black
Vinyl
tape
Figure 5.3.1: East circuitry used for testing
In the testing phase, circuit is implemented on the breadboard for testing as shown in
Figure 5.3.1. A 5V is used as the input voltage to all the ICs chip. The result shows
that when light is shined on both the reset LDR and the East LDR, the output is near
to zero volt (around 0.466V) and it will operate similarly to the dawn LDR ciruitry
when the reset LDR is covered with black vinyl tape.
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CIRCUITRY EXPERIMENTAL PHASE
5.4
Motor Driver circuitry
The following test is to built Dawn circuitry with Motor driver and using 4 LED
connected to the output to act as stepper motor.
XOR
D Flip-Flop
Figure 5.4.1: Drawn diagram and photograph showing the motor driver
The motor driver is designed as above Figure 5.4.1. 74HC74 (D Flip-Flop) and
74HC86 (2 input XOR gate) are used. They are integrated with the Dawn circuitry to
test the output result of the D Flip-Flop and XOR gate.
O/P 1
O/P 2
Figure 5.4.2: Output waveforms of D Flip-Flop
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CIRCUITRY EXPERIMENTAL PHASE
Figure 5.4.2 shows 2 outputs of the D Flip-Flop, where Pin 6 (O/P 1) and pin 7 (O/P
2) that are fed into XOR gate. This circuit is tested under normal lighting with LDR
measured approximately at 4.7KΩ and RB = 100kΩ, RL = 20kΩ.
XOR pin 1 set to VCC
XOR pin 1 set to GND
O/P A
O/P B
O/P C
O/P D
Figure 5.4.3: Output waveforms of Motor Driver (XOR pin 1 set to VCC or GND)
Figure 5.4.3 shows 4 output of the XOR IC chip. Pin 1 of the XOR IC chip is
designed for the rotation of the motor. When Pin 1 is connected to VCC, it will turn
clockwise. When Pin 1 is connected to GND, it will turn anti-clockwise. These 4
output waveforms correlate to the rotation which is based on the 2-phase Excitation
Signal time chart in Figure 3.2.3.3.
In such case, Pin 1 of XOR gate is connected to the reset pin of the East timer
circuitry. When light is shined on the reset LDR, the voltage to the reset pin drops
nearly to zero volt and it will result the motor to rotate anti-clockwise. When no light
is shined on LDR, the reset pin is at VCC volt, it will result the motor to rotate
clockwise.
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XOR
CIRCUITRY EXPERIMENTAL PHASE
Dawn
Motor Driver
D flip flop
circuitry
circuitry
Motor Driver
circuitry
4 LEDs
to act as
stepper
motor
Figure 5.4.4: Motor Driver Circuitry and overall circuit
Figure 5.4.4 shows four LEDs connected to the motor driver output to act as the 4
inputs of the motor. The result matches to the 2-phase Excitation Signal time chart
shown in Figure 3.2.3.3 of Chapter 3.2.3.
In this experiment, the speed of the 4 LEDs turning on and off depending on the light
intensity shone on the Dawn LDR. When light is very bright, the speed become faster
and speed slow down as the light gets dimmer. It stops when no light is detected.
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CIRCUITRY EXPERIMENTAL PHASE
5.5
Motor Driver circuitry with motor
In this experiment, the dawn circuitry with the motor driver circuitry is first connected
to the LEDs and stepper motor. However, the stepper motor does not rotate. It is
found out the LED drawn around half the voltage and resulted only 2.5V left into the
stepper motor. The LEDs are then removed and the motor driver output is connected
directly to the stepper motor.
Unfortunately, the stepper motor continues to remain not moving. The reason behind
is that the current is too weak to drive the motor. As such, transistors are added into it.
Transistors are introduced to amplify the current in order to rotate the motor shaft.
They also act as current regulating devices to control the current flowing through
them to ensure it is proportional to the biased current from the transistor base
terminal. In short, the transistor can be considered as a switch.
Four PNP transistors are added in the solar tracker to boost the weak electronic
signals into current powerful enough to drive the motor coils. Transistor is reliable
and inexpensive and the circuits built are low in cost. Figure 5.5.1 shows the example
of how PNP transistor works.
Figure 5.5.1: PNP transistor as a switch (ON mode and OFF mode)
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CIRCUITRY EXPERIMENTAL PHASE
The emitter of a PNP transistor is always tied to the fixed voltage (+VCC or GND)
when using transistors as switches. In additional, a diode is added into the transistor
circuitry to prevent voltage backslash in the reverse polarity whenever a coil is
switched off each time. The reverse induction generates very high voltage spike that
may cause the transistor to be damaged when the coils’ magnetic field collapses.
Besides that, the motor driver circuitry is also replaced with high powered ICs such as
74HC74 is being replaced by CD4013 while 74HC86 is being replaced by CD4070.
This is to ensure the output signal is strong enough to drive the motor. However, upon
the replacement, there was no signal at the output. This is due to the fact that the input
and output pin of the ICs are different though they are of the same XOR/ D flip flop.
This issue is resolved upon redesigning the wiring.
After the circuit is rewired, it is tested but with incorrect output signal. Detail
investigation showed that the set and reset pin of the D Flip-Flop is different from the
74HC86 family. They have to be connected to ground instead of connecting to the
VCC. After rewiring, together with the implementation of the PNP circuit, the motor
driver output produce 12V signal and rotates accordingly.
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CIRCUITRY EXPERIMENTAL PHASE
5.6
Integration of East, West and Dawn circuitry with Motor driver and motor
After the intial testing, all the LDR circuitries will be integrated together with the
motor driver circuitry and the stepper motor. As the output value from each LDR
circuitry is different, a type of gate is required to tabulate the 555 timer output values.
A truth table is used to define each possible scenerios in order to determine the
movement of the solar tracker.
Scenerio 1: At night
No light is shined on any LDR and no movement of the motor
Scenerio 2: At Dawn with only Dawn circuit detect light
The motor will move clockwise towards east
Scenario 3: Only East circuit detect light
The motor will move clockwise towards east
Scenario 4: East and West circuit detect light
No movement of the motor
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CIRCUITRY EXPERIMENTAL PHASE
Scenario 5: Only West circuit detect light
The motor will move anti- clockwise towards west
Note:
Pin 3 is the 555 timer Output pin
Pin 4 is the 555 timer Reset pin
The truth table and Karnaugh map was derived as shown in Table 5.6.1 and 5.6.2
Table 5.6.1: Truth Table
Table 5.6.2: Karnaugh map
From truth table and K map, it shows that E XOR W XOR D, therefore Exclusive OR
gate is used.
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CIRCUITRY EXPERIMENTAL PHASE
All the circuitries are intergrated together with the XOR gate and is implemented on
the breadboard with the schematics of the overall circuitry as shown in Figure 5.6.1
Figure 5.6.1: Overall Schematic Design
Results: The circuit is tested and works accordingly.
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DEVELOPMENT PHASE
CHAPTER 6: DEVELOPMENT PHASE
6.1
PCB Design
The schematic drawing and PCB design of the main circuitry in the solar tracker were done
by using the “Easy PC” software. Figure 6.1.1 shows the overall view of the PCB design
layout.
Figure 6.1.1: Overall view of the PCB Design Layout
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DEVELOPMENT PHASE
Figure 6.1.2: 3D design translated by “Easy PC” software
Top
Side
Bottom
Figure 6.1.3: Diagrams showing the PCB design in top, side and bottom views
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DEVELOPMENT PHASE
6.2
Circuit Board Development
Prior to PCB fabrication, the circuitry was first soldered onto the development board. Due
to inadequate experience, the initial wiring of the circuitry is rather untidy as seen from
the bottom view of the circuit board in Figure 6.2.1. Several unforeseen glitches and
issues occurred which are systematically resolved from thorough troubleshooting.
Figure 6.2.1: An overview of the Initial Circuit board (Top and Bottom views)
Figure 6.2.2 shows the finalized circuit board which is more neatly done as compared to
previous one. The soldering of the whole circuit board is done in different stages. The LM
555 timer circuitry is first soldered, followed by Dawn, East and West LDR circuits with
each respective LDR tested individually. The gates (XOR and the motor driver circuitry)
are then soldered and tested in the final stage. Such systematic soldering and testing allow
all soldering related problems to be resolved faster and easier.
Figure 6.2.2: An overview of the Finalized Circuit Board (Top and Bottom views)
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DEVELOPMENT PHASE
6.3
Hardware implementation
After main circuit board is completed, the sensor board is developed as follows:
Side View
Top View
Figure 6.2.3: Sensor Board
The boards are integrated together with the motor into a casing as follows:
Top View
Side View
Main circuit board
Stepper
motor
Figure 6.2.4: Solar Tracker
Batteries
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PROBLEMS AND SOLUTIONS
CHAPTER 7: PROBLEMS AND SOLUTIONS
7.1
Problems encountered
This chapter focuses on the problems encountered during the testing and development
phases.
Testing phase
1) The 5V supplied ICs cannot operate the 12V motor. Motor still cannot move with
the implementation of PNP transistor.
2) Clockwise and anti-clockwise rotation of the motor cannot be determined.
3) During the experiments on the west and east circuits, when light shines on both
the West and East reset LDR, East 555 timer shows an output of “High” with reset
pin (pin 4) around 1V while West 555 timer produces pulses that resulted motor to
rotate anti-clockwise. An output of “High” is expected and thus AND gate is used.
Unfortunately, the result is incorrect. This error is due to the fact that when light
shines on the East reset LDR, the voltage at reset pin (pin 4) is around 0.4V and
causes the 555 timer to be “LOW” at output. The datasheet is interpreted wrongly
with wrong truth table created. Problem is resolved with new truth table created
and AND gate is replaced by XOR gate.
Hardware implementation phase
4) Timer does not produce correct signal.
5) The torch light used for the testing can neither be too near nor far from the solar
tracker. The stepper motor will not move although it produces audible sound.
6) When the sensor board is connected to the motor, the motor does not move.
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PROBLEMS AND SOLUTIONS
7) The LDRs cannot accurately determine the light strength and cause the motor not
able to react accordingly.
7.2
Solutions
1) 5V ICs chips are replaced by higher powered ICs.
2) To rotate anti-clockwise, the input value at motor driver XOR must be low and
vice versa. Thus, the reset pin of the east timer circuit is used to enable the motor
to rotate correctly.
3) The resistance values at the East Reset LDR circuit is fined tune until correct
output is produced in which AND gate is replaced by XOR gate.
4) Soldering issues such as wrong or no connections are resolved.
5) Initial stepper motor of a step angle of 7.5 degree with 36 ohms resistance is
replaced with a step angle of 1.8 degree with 60ohms resistance.
6) The motor rotates accordingly under “zero weight” situation in the testing phase.
However, with sensor board attached to it, the required force is insufficient for
motor movement which is resolved by tuning the resistors RB and RL .
7) The LDRs are required to place in certain tilted angles to receive light.
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CONCLUSION AND RECOMMENDATION
CHAPTER 8: CONCLUSION AND RECOMMENDATION
8.1
Conclusion
Throughout this project, an automatic solar tracing system has been designed and
constructed to track and achieve the best alignment with the sunlight position. Several
critical phases ranging from Literature study to design, experimental, development of
prototype and testing have been completed. The objective of constructing the solar
tracker from scratch through the use of only electronics components is successfully
met. The electrical characteristic of each component is tested to confirm if its
specification is met. Although the project has certain limitation due to the hardware
portion which has been discussed in Chapter 5, it also provides an opportunity for
further improvement in the development of the solar tracker. The overall experience
gain in the troubleshooting as well as the critical skill set gain in project management,
systematic problem solving approach, time management, stress management and good
communication will certainly be extremely beneficial in future.
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CONCLUSION AND RECOMMENDATION
8.2
Recommendation
The goal of this project is to achieve a working prototype within the provided
timeline. Unfortunately, due to the time constraint, the hardware does not function as
expected. Therefore, future work for improvements can be made upon this design.
The following recommendations to improve the design are suggested as follows:

Different light sensor such as phototransistor can be used to increase the
accuracy and sensitivity for tracking the sun light to amplify the received signal
strength and improve the tracking precision.

Microcontroller using software programming to read input analog voltage
from the sensors, compare the values between East and West sensors and produce
accurate output digital signal to control the motor movement.

Replacing of the current stepper motor driver with a market available
integrated ICs chip.

To increase the tracking precision and accuracy by replacing the single axis
design to a dual axis design that is more complex and costly.
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CRITICAL REVIEW AND REFLECTION
CHAPTER 9: REVIEW AND REFLECTION
This project has provided me invaluable experience and better insight on how to build a
working prototype from scratch. A combination of varieties of skill set ranging from project
management, systematic problem solving approach, time management, stress management
and good communication are all critical to the success of the project. The ability of putting
theories gain through research and literature study into practical use will directly impact the
project outcome. This project allows me to handle several adversity situations when there are
many unforeseen circumstances arises that required me to think solutions to the problems in
all angles.
The project was kicked off with much focus on the research portion through literature review.
Market available solar trackers were studied in details in order to provide me a better
understanding on the various components required to build up a prototype. As a considerable
amount of time was spent in this area, a Gantt chart was used for me to ensure the risk of my
project lagging behind was minimized. The progress of the project was not smooth as many
unforeseen issues started to surface out. Work commitments such as working overtime and
short term oversea attachment has worsen the situation which resulted in not having sufficient
time to do the project. Furthermore, there is a lack of concentration during the exam period
and assignment deadlines. Fortunately, most of the problems are able to be solved within the
timeline after a proper time management was put in place.
During the research phase, I started to evaluate a variety of components as well as how to
integrate them together. I purchase several components and tried out various connections.
With the advice from my tutor, I am able to select the required components correctly. In the
testing phase, multiple problems arise in which some of these are contributed by
misunderstanding of the datasheet explanation or wrong methods approached. Nevertheless,
the hand sketch schematic design is finally put up after several testing. A series of trial run
on different software was engaged to do the schematic and PCB design. Some of them either
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CRITICAL REVIEW AND REFLECTION
do not have the required components of the solar tracker or they are somehow not user
friendly. Finally, simple trial software is used and managed to produce the desired output.
Many problems arise in the soldering of the PCB circuit board and the hardware integration.
The first circuit board is not successful as there are shorts and opens in the connection due to
messy wiring arises from inexperience. A second PCB circuit board is then soldered with
proper layout planning. Upon the integration of all components together, the result is
satisfactory. Deep dive understanding of the problem and intensive troubleshooting showed
that it is due to mismatch on the weight of the sensor board, the motor torque and the
frequencies which are required to drive the motor.
This project stretched throughout two semesters which is relatively not easy but certainly
worthwhile. It has provided me a vast and fruitful experience. Although the solar tracker did
not perform up to expectation, the overall experience gain has far surpassed the project
outcome.
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REFERENCES
REFERENCES
[1]
http://en.wikipedia.org/wiki/Renewable_energy
[2]
http://solarbuster.com/technology
[3]
http://encyclobeamia.solarbotics.net/articles/solar_cell.html
[4]
A.K. Saxena and V. Dutta, “A versatile microprocessor based controller for solar
tracking,” in Proc. IEEE, 1990, pp. 1105 – 1109.
[5]
http://makingelectricityathome.blogspot.com/2009/09/making-electricity-at-homesolar-panels.html
[6]
http://www.hardwaresphere.com/2009/02/03/the-solar-tree-backyard-green-powergenerator/
[7]
http://www.livingonsolar.com/solar-tracker.pdf
[8]
http://www.engadget.com/2007/04/15/portasol-solar-tracker-continuously-faces-thesun/
[9]
http://www.solar-tracking.com/
[10]
http://ezinearticles.com/?Increase-Your-Solar-Panel-Output-by-Using-a-SolarTracker&id=3646483
[11]
http://www.electronics-tutorials.ws/io/io_4.html
[12]
http://www.technologystudent.com/elec1/ldr1.htm
[13]
http://en.wikipedia.org/wiki/Photoresistor
[14]
T.A. Papalias and M. Wong, “Making sense of light sensors,”
[15]
http://www.mstracey.btinternet.co.uk/technical/Theory/theorysensors.htm
[16]
http://en.wikipedia.org/wiki/Solar_cell#cite_note-1
[17]
http://www.solarbotics.net/starting/200111_dcmotor/200111_dcmotor2.html
[18]
Moberg, Gerald A., “AC and DC motor control”
[19]
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdc.html
[20]
http://people.ee.duke.edu/~cec/final/node59.html
[21]
Sandhu, Harprit, “Running small motors with PIC microcontrollers”
[22]
http://zone.ni.com/devzone/cda/ph/p/id/286
[23]
http://home.cogeco.ca/~rpaisley4/Stepper.html
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REFERENCES
[24]
William H and Alan W,” Handbook of Small Electric Motors”
[25]
R. Condit and D. W. Jones, “Stepping motor fundamentals,”
[26]
http://www.imagesco.com/articles/picstepper/02.html
[27]
Acarnley, P. P, “Stepping motors: a guide to modern theory and practice”
[28]
Kenjo, Takashi , Stepping motors and their microprocessor controls
[29]
Eduardo Lorenzo, “Solar Electricity: Engineering of Photovoltaic Systems”
[30]
Mark Z. Jacobson, “Review of Solutions to Global Warming, Air Pollution, and
Energy Security”
[31]
Iovine, John, “PIC microcontroller project book for PIC Basic and PIC Basic Pro
compilers”
[32]
Ramsey, Dan, “The complete idiot's guide to solar power for your home”
[33]
http://www.machinetoolhelp.com/Automation/systemdesign/stepper_dcservo.html
[34]
http://www.seattlerobotics.org/guide/servos.html
[35]
http://www.cs.uiowa.edu/~jones/step/
[36]
http://www.imagesco.com/articles/picstepper/02.html
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APPENDIX
APPENDIX
APPENDIX A: Schematic Diagram
A1: Automatic Solar tracker Schematic Design
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APPENDIX
A2: Automatic Solar tracker PCB Design
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APPENDIX
A3: Initial Gantt Chart
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APPENDIX
A4: Revised Gantt Chart
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APPENDIX
APPENDIX B: Data Sheet
B1: LM 555 timer
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APPENDIX
B2: Exclusive-OR Gate
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APPENDIX
B3: D-Type Flip Flop
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APPENDIX
B4: LM7812 Voltage Regulator
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APPENDIX
B5: CdS Photocell (LDR)
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APPENDIX
B6: PNP Transistor
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APPENDIX
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APPENDIX
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