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DEVELOPMENT OF SMART PV TRAVEL PHONE CHARGER
NIK MOHD FARID BIN NIK IBRAHIM
UNIVERSITY MALAYSIA PAHANG
iv
.
ABSTRACT
Solar energy is a one of the alternative renewable energy resource. The energy
resource which directly produced by the sun can be converted to electricity by using
solar cell. The applications that using photovoltaic technology is a solar cell phone
travel phone charger. Solar cell phone charger can save energy compared to electric
socket cell phone charger besides not contributing to environmental pollution. The
weakness of this type of energy is it‟s depending on the existence or the brightness of
sunlight. The project aims to develop charging cell phone using Photovoltaic (PV)
otherwise to minimize electricity energy usage. The project also includes different
from conversional phone charger due to this travel phone charger have storage
battery to always be used when needed at certain times. In addition, this project using
the buck converter circuit to monitor the voltage level of the continuous at rated 5
Volt even of the input voltage from solar cell is constantly changing. If the voltage
from solar cell exceeds the permissible limits, its will be stabilized by using solar
charge controller (SCC) to maintain and the voltage can be set to normal state using
LM 2574 as step-down converter function. Thus the device will obtain a continuous
power and protected from the effects of under voltage and overvoltage.
Furthermore, this travel phone charger is also equipped PIC16F688 for the display
using LCD in order to reading of the storage battery can always be observed during
the running.
v
ABSTRAK
Tenaga solar merupakan salah satu sumber tenaga alternatif yang boleh diperbaharui.
Sumber tenaga yang dihasilkan secara terus oleh sinaran cahaya matahari ini boleh
ditukar menjadi tenaga elektrik dengan menggunakan Photovoltaic (PV) yang juga
di kenali sebagai sel solar. Antaranya salah satu aplikasi yang meggunakan sistem ini
ialah pengecas bateri telefon mudah alih. Pengecas bateri solar ini boleh
menjimatkan tenaga berbanding pengecas soket elektrik yang sedia ada disamping
tidak menyumbang kepada pencemaran alam sekitar. Kelemahan sumber tenaga ini
adalah disebabkan kebergantungan kepada kehadiran atau kecerahan pada cahaya
matahari. Tujuan projek ini adalah untuk membangunkan pengecas bateri telefon
mudah alih dengan menggunakan Photovoltaic (PV) dalam hal lain untuk
mengurangkan kebergantungan kepada penggunaan tenaga elektrik. Projek ini juga
mempunyai kelainan daripada pengecas konvensional kerana pengecas telefon
mudah alih ini mempunyai bateri simpanan agar sentiasa dapat digunakan apabila
diperlukan pada waktu-waktu tertentu. Selain itu, projek ini menggunakan kaedah
iaitu litar penukar perendah untuk memerhati tahap voltan dari sel solar secara
berterusan pada kadar 5 Volt walaupun voltan masukan dari sel solar sentiasa
berubah. Jika voltan dari sel solar melebihi tahap yang dibenarkan, voltan tersebut
akan ditetapkan kepada keadaan normal menggunakan kawalan pengecas solar
(SCC) untuk kekalkan dan voltan akan di tetapkan kepada keadaan normal dengan
menggunakan LM2574 iaitu bertindak sebagai fungsi penukar perendah. Disebabkan
itu, alatan akan mendapat tenaga yang berterusan dan dilindungi dari kesan akibat
kekurangan voltan dan lebihan voltan. Disamping itu, pengecas mudah alih ini juga
dilengkapi PIC16F688 untuk paparan LCD supaya bacaan pada bateri simpanan
sentiasa dapat diperhatikan sepanjang proses berjalan.
vi
TABLE OF CONTENTS
CHAPTER TITLE PAGE
DECLARATION I
DEDICATION II
ACKNOWLEDGEMENT III
ABSTRACT IV
ABSTRAK V
TABLE OF CONTENTS VI
LIST OF TABLES X
LIST OF FIGURES XI
LIST OF SYMBOLS XIV
LIST OF APPENDICES XV
1 INTRODUCTION 1
1.1 Background 1
1.1.1 Advantages of Alternative Cell
Phone Charger Using Photovoltaic 2
1.2 Objective 2
1.3 Scope 2
1.4 System Description 3
1.5 Problem statement 5
1.6 Outline of Thesis 6
vii
2 LITERATURE REVIEW 8
2.1 Solar Energy 8
2.1.1 Advantages of Solar Energy 9
2.2 Photovoltaic (PV) Cell 10
2.2.1 Advantages of Photovoltaic Systems 14
2.3 DC-DC Converter 14
2.3.1 Buck Converter (Step-down) 14
2.3.2 Basic operation of Buck Converter 15
2.4 Battery charger using Electricity 16
2.5 Battery charger using Photovoltaic (PV) 17
2.6 Lithium-Ion Battery 18
2.7 Lead-Acid Battery 21
2.8 Integrated circuit (IC) LM2574 24
2.9 Solar charge controller 27
3 RESEARCH METHODOLOGY 30
3.1 Introduction 30
3.2 Hardware Development 30
3.3 Overall System Design using LM2574 32
3.4 Overall System Design using PIC
Microcontroller 33
3.5 Software Development 34
viii
4 RESULT AND DISCUSSION 40
4.1 Introduction 40
4.2 Result and Discussion 40
4.2.1 Software 41
4.2.1.1 Software using ISIS Proteus for
PIC16F688 41
4.2.1.2 Power supply circuit for PIC 42
4.2.2 Hardware 43
4.2.2.1 Hardware using Buck converter 43
4.2.2.2 Hardware using PIC based Digital
Voltmeter and LCD Displays 47
4.3 Data
4.3.1 Data for Photovoltaic Panel 52
4.3.2 Data for Battery Storage (Lead-Acid) 56
4.3.3 Data for Charging Voltage (Lead-Acid) 61
4.3.4 Data comparison type of Phone Charger 65
5 CONCLUSION AND RECOMMENDATIONS 66
5.1 Conclusions 66
5.2 Recommendations 67
REFERENCES 68
APPENDICES 70
ix
APPENDIX A (Gantt Chat PSM 1 and PSM 2) 71
APPENDIX B (Software using C Language Micro C Pro for PIC) 72
APPENDIX C (PIC16F688 Datasheet) 74
APPENDIX D (LM2574 Datasheet) 77
APPENDIX E (LM7805 Datasheet) 87
APPENDIX F (Lead Acid Battery Datasheet) 97
x
LIST OF TABLES
TITLE NO. TITLE PAGE
Table 4.1 Pin out of LCD Display 50
Table 4.2 Data for Solar Panel
52
Table 4.3 Data for Solar Panel (12 hours)
54
Table 4.4 Data for Battery Storage (1 hours) 56
Table 4.5 Data for Battery Storage (12 hours) 59
Table 4.6 Data for Charging Voltage
61
Table 4.7 Data of comparison
65
xi
LIST OF FIGURES
FIGURE NO. TITLE PAGE
Figure 1.1 Global Block Diagram – Development of
Smart PV Travel Phone Charger 3
Figure 2.1 Ideal I-V curve for a PV cell 10
Figure 2.2 Typical current voltage I-V curve 11
Figure 2.3 PV cell, modules and array 12
Figure 2.4 Photovoltaic cell 13
Figure 2.5 A basic buck converter topology circuit 15
Figure 2.6 Equivalent circuit for switch closed 16
Figure 2.7 Equivalent circuit for switch opens 16
Figure 2.8 Charger battery by using electricity 17
Figure 2.9 Charger battery by using Photovoltaic (PV) 18
Figure 2.10 Li-ion battery 20
Figure 2.11 Lead-acid rechargeable battery 21
Figure 2.12 Discharge curves for one cell of each of the five
main types of rechargeable battery compared a
typical discharge rates 22
Figure 2.13 Block diagram and typical application 25
Figure 2.14 Typical performance characteristics 26
Figure 2.15 Solar charge controller 27
Figure 2.16 Insolation performance of a PV array 28
Figure 2.17 Temperature performance of PV array 28
Figure 2.18 Connections Solar Charge Controller with
Buck converter 29
xii
Figure 3.1 Process hardware development 31
Figure 3.2 Pin of LM2574 32
Figure 3.3 Block diagram when using LM2574 (Buck
converter) 32
Figure 3.4 Circuit using PIC microcontroller 33
Figure 3.5 Block diagram using PIC microcontroller 34
Figure 3.6 Project flow for PIC 35
Figure 3.7 PIC kit 2 Programmer Software 38
Figure 3.8 Import hex file with successfully 39
Figure 3.9 Position of PIC at USB Programmer 39
Figure 4.1 Simulation by ISIS Proteus for LCD display
(For 0V) 41
Figure 4.2 Simulation by ISIS Proteus for LCD display
(Increased until 6V) 42
Figure 4.3 Simulation by ISIS Proteus for Power supply
circuit 43
Figure 4.4 Buck converter complete design 43
Figure 4.5 Buck converter charging schematic design 44
Figure 4.6(a) Simulation circuit by using Target 3001 45
Figure 4.6(b) Verify of the output 5V using buck converter 45
Figure 4.6(c) Testing circuit for measure output 5V at USB 46
Figure 4.7 Digital Voltmeter hardware testing process 47
Figure 4.8 Testing process to verify value using Digital
Voltmeter and Multimeter 48
Figure 4.9 Pin out of LCD Display 49
Figure 4.10 LCD Contrast connection 51
Figure 4.11 LCD Contrast (Slow contrast) 51
Figure 4.12 LCD Contrast (High contrast) 51
Figure 4.13 Graf for Solar Panel (Voltage vs. Time) 52
xiii
Figure 4.14 Graf for Solar Panel (Current vs. Time) 53
Figure 4.15 Graf for Solar Panel (Voltage vs. Time) for
12 hours 54
Figure 4.16 Solar Panel position side A 55
Figure 4.17 Solar Panel position side B 55
Figure 4.18 NPH Discharge Characteristic curves 57
Figure 4.19 Graf for Battery Storage (Lead-acid) for 1 hours 58
Figure 4.20 Graf for Battery Storage (Lead-acid) for
for 12 hours 59
Figure 4.21 Value of charging process for Battery Storage 60
Figure 4.22 Graf for charging voltage (Voltage vs. Time) 62
Figure 4.23 Testing of charging voltage process at
Battery Storage with 5.98V 63
Figure 4.24 Testing of charging voltage process at
Battery Storage with 5.99V 64
xiv
LIST OF SYMBOLS
I Ampere
V Voltage
PV Photovoltaic
LED Light Emitting Diode
LM2574 Step-down converter
LM7805 Voltage regulator
DC Direct Current
AC Alternating Current
LIB Lithium-ion Battery
PIC Peripheral Interface Controller
IC Integrated Circuit
Frequency
I/O Input/output
VDD Supply Voltage
DVM Digital Volt Meter
SCC Solar charge controller
NPH Normal Pressure Hydrocephalus
xv
LIST OF APPENDICES
APPENDIX TITLE PAGE
A Gantt Chart PSM 1 and PSM 2 71
B Software using C Language
Micro C Pro for PIC 72
C PIC16F688 Datasheet 74
D LM2574 Datasheet 77
E LM7805 Datasheet 87
F Lead Acid Battery Datasheet 97
1
CHAPTER 1
INTRODUCTION
1.1 Background
Due to the energy crisis, renewable energy sources have been deeply concerned
as possible solutions to remain resources on the earth. Among these energy sources,
solar energy, a free conversion, non-polluted and inexhaustible energy source, has
been use to generate electricity for decades.
The solar energy which directly produced by the sun and it can be converted to
electricity energy by using solar cell. For example, one of the applications that using
Photovoltaic (PV) technology is battery charger cell phone. Solar cell is a device that
converts the energy of sunlight directly into electricity by the photovoltaic effect.
The main focus of this project is to design the charger with environmentally friendly
materials and powered by alternative energy sources. The energy savings for battery
charger cell phone is important in order to make sure that energy resource can be
used for a long term.
This project consists of five elements which are Photovoltaic (PV) panel, solar
charge controller, buck converter circuit (DC-DC Converter) with rechargeable
battery (lead-acid type), PIC microcontroller and DC loads (lithium-ion battery). The
buck converter circuit is used to set the normal charging voltage level at 5 Volt. The
charge controller are used to stabilized the current and monitor the voltage or current
level at solar cell. The PIC microcontroller aims to measure the battery storage from
buck converter circuit.
2
1.1.1 Advantages of alternative cell phone charger using Photovoltaic (PV)
When using a solar cell phone charger it able to store electricity for a few days.
There are several advantages when using the cell phone charger solar such as:
i. Plugging a charger to an electric socket can cause a shock to the wallet so
using photovoltaic to charge batteries can save money.
ii. Invest in a solar battery charger not have to pay any bills and neither to pay
maintenance costs.
iii. For the green consumer, rechargeable batteries are a great way to prevent
toxic chemicals like alkaline from finding their way into landfills, or just
reducing the cost of buying fresh, disposable batteries.
1.2 Objective
The objectives of this project are as follows:
i. To design a smart photovoltaic (PV) travel phone charger by using
PIC16F688.
ii. To develop a DC-DC converter with stabilized output 5 Volts.
iii. To simulate the circuit by using Target 3001 and Proteus simulation software.
1.3 Scope
There are two main elements considered in this project which are:
i. To understand theoretical aspect of photovoltaic panel, PIC and including
working principles, characteristics and specifications.
ii. To develop the travel phone charger using Photovoltaic (PV) systems.
3
1.4 System Description
Figure 1.1: Global Block Diagram – Development of Smart PV Travel Phone
Charger
4
The photovoltaic charger system consists of five subsystems, each with its own
function. These five subsystems are connected in accordance with the block diagram
presented in Figure 1.1.
The first subsystem (Solar Panel) consists of PV module as main element input
source in this project. This PV module has a rated power in 9.4 V and is formed by 3
photovoltaic cells connected in parallel (more technical specifications may be
consulted in detail). Due to not have suitable rated, these solar panel cells are used in
project.
The Solar Charge Controller (second subsystem) is used to increase the current
in 1 Ampere due to the solar panel cannot support current for charging process. If
current not enough, the charging process cannot charging with successfully.
Furthermore, it can be apply to backup support from overcharging for storage battery
in charging process occurs after diode zener at buck converter circuit.
The DC-DC Converter element (third subsystem) consists of one rechargeable
battery from lead-acid types and buck converter charging unit. It due to lead-acid
battery has high capacity storage from other battery in Photovoltaic systems [11].
The buck converters are used for step-down or stabilized voltage at 5 Volt (suitable
for phone charger charging).
The DC loads (fourth subsystem) consists of a rechargeable Lithium-ion (Li-
ion) battery from mobile phone. This battery has an output voltage of 3.7V and an
energy storage capacity of 550mAh/1000mAH (depends the type of capacity battery
are used for mobile phone from supplier)
The measurements (fifth subsystem) are used to measure capacity of the storage
battery at the buck converter and solar panel by using PIC16F688. If the full charge
battery capacity, the LCD act as display with 6V depends the type battery are used in
the project.
5
1.5 Problem Statement
Nowadays, the portable equipments relying on the solar energy as a power
supply are widely used in the daily life [1]. With the increase of the energy demand
and the concern of environmental pollution around the world, photovoltaic (PV)
system is becoming more and more popular [1]
Due to the energy crisis, alternative energy sources have been deeply concerned
as possible solutions to remain resources on the earth [2]. Among these energy
sources, solar energy, a free conversion, non-polluted and exhaustible energy source,
has been used to generate electricity for decades [2].
The main purpose of establishing the working of mobile phones using solar
energy is to overcome the constraint of enormous emission of Carbon-di-Oxide in to
the atmosphere, hugely contributing to the depletion of ozone layer [3]. By using the
photovoltaic (PV) system, the system depends on sun energy as power supply which
is only available in limited period. It causes the limited energy supply. So, the system
must use the energy as minimum as possible but still can operate efficiently
A solar cell phone charger uses the energy of the sun to charge up mobile
phone. If someone are outdoors a lot, or do not have ready access to an electrical
outlet, getting a telephone charged can be principal hassle. With a solar cell phone
charger, we can easily use the energy of the sun to charge cell phone anytime and
anywhere. Using photovoltaic cells, a solar cell phone charger can rapidly turn the
power of the sun into electricity. This electricity can be used to recharge telephone
anywhere. A solar panel phone charger can be vital on a camping trip or an outdoor
adventure travel.
6
1.6 Outline of Thesis
This Development of Smart PV Travel Phone Charger final thesis is consists of
five chapters including this chapter. The content of each chapter are outlined as
follows.
For Chapter 1(Introduction) it will be described about the introducing the
overview of the project including the background, objectives, problem statement and
scope of the project.
For Chapter 2 explained about the reviews on previous researches conducted
that is related to this project. Before starting the project, the background and
literature review about development of smart PV travel phone charger has been
studied in order to understand more about the operation and principle of charger
solar.
For Chapter 3 it includes the project methodology. This will explain how the
project was organized and the flow of the system designed. Before developing the
prototype, the simulation has been done to make sure that the circuit would be
working properly.
For Chapter 4 explained the result and discussion. The result will be analyzed
and discussed. This chapter shows the result achieved by doing this project. The
result are categorized into three parts includes the hardware, software and analysis of
the system.
For Chapter 5 will be explained about the conclusion from this project. The
overall conclusions of this project that have been completed. The final chapter which
is chapter five elaborates the conclusion and recommendation of the project. The
8
CHAPTER 2
LITERATURE REVIEW
2.1 Solar Energy
Solar energy is the light and radiant heat from the sun that influences Earth's
climate, weather and sustains life. Solar power is sometimes used as a synonym for
solar energy or more specifically refer to electricity generated from solar radiation.
Solar energy technologies can provide electrical generation by heat engine or
photovoltaic means, space heating and cooling in active and passive solar buildings,
portable water via distillation and disinfection, day lighting, hot water, thermal
energy for cooking, and high temperature process heat for industrial purposes. Solar
energy refers primarily to the use of solar radiation for practical ends. All other
renewable energies other than geothermal derive their energy from energy received
from the sun.
Currently, our society‟s energy demands are fulfilled using conventional energy
sources such as water, coal, oil, natural gases or uranium [4]. The production of
energy using these conventional sources is a cause of concern of many
environmentalists [4]. The major problems can be quoted as follows:
9
i. It causes atmospheric pollution, climate changes or nuclear waste and thus can
endanger our living condition on the earth.
ii. The extensive use of these limited conventional energy sources may result in
complete depletion of energy sources and hence, there is no guarantee of energy
supply for future.
The above mentioned problems can be solved by using renewable energy sources
such as sun and wind. The renewable energy sources use natural resources and do not
cause any pollution. Hence they are termed as green energy sources [5]. Moreover,
these renewable energy sources only use a small part of the flow that is why they
cannot damage natural surrounding and also do have the risk of being depleted. Sun
is considered as a potential source of renewable energy. Hence, the use of solar
energy for applications such as generation of electricity, running of automobiles, etc
is becoming popular. The generation of electricity using solar energy is done using
photovoltaic technology [6].
2.1.1 Advantages of Solar Energy
Solar technologies are broadly characterized as either passive or active
depending on the way they capture, convert and distribute sunlight. Active solar
techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful
outputs. The advantages of solar energy are as following:
i. Solar energy is a renewable resource. Although it cannot be utilized at night
or on cloudy days, its availability may be generally relied upon day after day.
ii. Solar cells are long-lasting and require very little maintenance.
iii. Solar energy is non-polluting. Of all the advantages of solar energy over oil,
this is perhaps the most important. The burning of oil releases carbon dioxide
and other green house gases into the air. In addition to this, the process of
obtaining it may result in damaged ecosystems through dredging or spills.
10
iv. Although solar panels and their accessories (solar lights, etc.) may be
expensive to buy at the onset, money is saved in the long run. This is because
energy from the sun is widely available and free.
v. Solar powered lights and other solar powered products are very easy to
install. This is because there are few wiring issues and little need to ever dig
supporting trenches.
2.2 Photovoltaic (PV) Cell
On the thesis the solar panel serves as power supply to the circuit. It receives
light from the sun and converts this to energy. The photovoltaic cell is a usual power
source where as most sources of electrical power are constant voltage sources, such
as a battery, a PV cell is a constant current source. The PV cell only displays this
constant current characteristic up to a limiting where the current collapses. For an
ideal PV module the voltage where the current collapses would be at the open circuit
voltage, Voc
Figure 2.1: Ideal I-V Curve for a PV cell
11
Figure 2.2: Typical current-voltage I-V curve
The slight current drop between points M and A is a result of some of the
current passing through the internal resistance of the PV cell. Between points A and
S the load resistance increases forcing some of the current to flow through the diode
resulting in the fast drop in current to the load. This continues until point S where all
the current flows through the diode and the internal resistance.
Where the PV operates on this I-V curve is greatly determined by the
insulations, array voltage, cell temperature and the load connected to the array.
According to [14] by altering the amount of sun light that is available to the PV
module the current that the module can produce is also altered. The current and
power output of the used solar panel is approximately proportional to illumination
intensity (irradiance). At a given intensity, the module voltage is determined by the
characteristics of the load.
According to the conclusions achieved in [15] the effect of temperature on the
current of a PV cell is only small. By increasing the temperature a slightly higher
current is produced, however this increase in temperature has a negative effect on the
cell voltage. Increasing the temperature forces the diode in Figure 4 to conduct at a
lower voltage therefore reducing the PV voltage where the curve collapses and
greatly reducing the output power
Figure 2.2 shows the load lines for different load resistances. The slopes of
these load lines are given by 1/R. So, lower resistances result in steeper load lines
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