UNIVERSITI MALAYSIA SABAH SCHOOL OF ENGINEERING AND INFORMATION TECHNOLOGY Design Project KE 30602 Final Report Lecturer name : Yoong Hou Pin Team member : Albert Ling Hoe Ying (BK09110140) Norrahmah Binti Salleh (BK08110327) Kong Mei Chie (BK09110029) Azahar B. Ali (BK09160210) Nur Fakhriah Binti Mohd Yusuf (BK08160432) Siti Hajar Binti Basuni(BK09110030) Date of Submission : 4 June 2012
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UNIVERSITI MALAYSIA SABAH
SCHOOL OF ENGINEERING AND INFORMATION TECHNOLOGY
Design Project
KE 30602
Final Report
Lecturer name : Yoong Hou Pin
Team member : Albert Ling Hoe Ying (BK09110140)
Norrahmah Binti Salleh (BK08110327)
Kong Mei Chie (BK09110029)
Azahar B. Ali (BK09160210)
Nur Fakhriah Binti Mohd Yusuf (BK08160432)
Siti Hajar Binti Basuni(BK09110030)
Date of Submission : 4 June 2012
Final Report
Maximum Power Point Tracking
(MPPT)
Client : Mr. Yoong
Project Manager : Mr. Yoong Hou Pin
Project Leader : Albert Ling Hoe Ying
Abstract
The project works with maximum power point tracking (MPPT) using the Perturb and Observe (P&O)
algorithm. The P&O algorithm is implemented using the controller make up of logic components such as
voltage follower, voltage inverter, differentiators, comparators, and X-OR gates. The solar energy
harvested from solar panel is fed into the MPPT system to acquire maximum power output at the load.
Typical solar panel works with low efficiency such < 15% thus, maximizing from the solar panel energy
is a necessity to achieve optimum performance of solar energy. A simple MPPT system is built to
maximize the power of solar panel (80W).
TABLE OF CONTENT
CHAPTER TITLE PAGE
ABSTRACT i
LIST OF TABLE ii
LIST OF FIGURE iii-iv
LIST OF ABBREVIATION v
1 Introduction
1.1 Overview 1
1.2 Power Supply Research 2
1.3 MPPT Research 2
1.4 Objective 3
1.4.1 Problem statement 3
1.4.2 Requirements 3
1.4.3 Safety Feature 4
1.4.4 Tolerance/Accuracy 4
1.4.5 Input/output Definition 4
1.4.6 Operation Environment 4
1.4.8 Hazardous Level 4
1.4.9 Overshoot Protection 4
1.5 Scope of work 5
1.5.1 Academic Review 5
1.5.2 Mathematical Modeling 5
1.5.3 Simulation 5
1.5.4 Hardware Realization 5
1.5.5 Testing 5
1.5.6 Calibration 6
1.6 METHODOLOGY 6
1.6.1 Academic Review 6
1.6.2 Mathematical Modeling 6
1.6.3 Simulation 7
1.6.4 Hardware Realization 7
1.6.5 Testing 7
1.6.6 Calibration 8
2 LITERATURE REVIEW
2.1 Solar energy 9
2.2 The concepts behind solar panel 10
2.3 The Characteristic of Solar Panel 11
2.4 Side Effect to the Solar Panel 12
2.4.1 Panel Arrangement/ Orientation 12
2.4.2 Roof and Panel Pitch 12
2.4.3 Temperature 12
2.4.4 Partial Shading 13
2.5 Perturb and Observe (P&O) Algorithm 13
2.6 Buck Converter 15
2.6.1 Continuous mode 16
2.7 Impedance matching 18
3 LIST OF COMPONENT
3.1 Resistor 20
3.2 Capacitor 21
3.3 PIC (Programmable Interface Controllers) 22
3.4 D flip-flop 23
3.5 Operational Amplifier ( Op Amp ) 24
4 OPERATION OF ELECTRONIC PARTS
4.1 Introduction 25
4.2 Solar Array 26
4.3 Controller 27
4.3.1 Voltage Follower 27
4.3.2 Voltage Inverter 28
4.3.3 Analog Multiplier 29
4.3.4 Differentiators 29
4.3.5 Comparators 30
4.3.6 XOR gate 31
4.3.7 D Flip-Flop 32
5 SYSTEM MODELING
5.1 Input and output definition 34
5.2 Detail design and drawing 34
5.3 Operation of MPPT system using P&O algorithm 34
5.4 Buck converter operation 36
5.5 Buck converter detail design 38
5.6 ADC scaling in PIC 39
6 FABRICATION
6.1 Prototype picture 41
6.2 Comments 41
7 KEY PERFORMANCE INDEX
7.1 Time performance index 42
7.2 Gantt Chart 43
7.3 Comments on TPI and Gantt Chart 44
7.4 Cost performance index 45
8 CONCLUSION AND FUTURE WORK
8.1 Conclusion 47
8.2 Future work 47
REFERENCE 48
APPENDIX 49
ii
LIST OF TABLE
TABLE
NUMBER
TITLE PAGE
1 Level of efficiency of different type of material solar panel 10
2 PRE and CLR function table 31
3 Circuit operation of MPPT by P&O algorithm 35
4 Week number in dates 42
5 Weekly TPI for MPPT project 42
6 Simplified schedule of project 44
iii
LIST OF FIGURE
FIGURE
NUMBER
TITLE PAGE
1 I-V Curve of typical solar 3
2 p-n junction of solar panel 10
3 I-V curve of different Solar Panel power 11
4 I-V Photovoltaic Characteristics for four different irradiation levels 14
5 P-V photovoltaic characteristics for four different irradiation levels 15
5.1 Thevenin Equivalent circuit 19
6 Resistor Color Code 21
7(a) Electrolytic Capacitors (Electrochemical type capacitors) 22
7(b) Ceramic Capacitors 22
8 PIC (Peripheral Integrated Circuit) 22
9 D flip-flop Diagram 23
10 D flipβflop: (a) Truth Table and (b)Timing Diagram 23
11 Operational Amplifier ( Op Amp ) 24
12 MPPT Charge Controller Circuit 25
13 Specifications of solar panel (Sharp NE-80E2EA) 26
14 Voltage follower connection 27
15 Inverting Op-amp connection 28
16 Connection of analog multiplier AD633 29
17 Voltage and Power Differentiator Connection 30
iv
18 Power and voltage comparators 31
19
(a) Connection diagram of IC7486, (b) XOR truth table, (c) Connection of
XOR gate in the circuit
32
20 74HC74 D-Flip-flop connection 32
21 Simple block diagram for overall system. 34
22 Full schematic diagram for MPPT system and Buck Converter 35
23 Flow chart for MPP tracking 35
24 The Circuit operation chart. 36
25 Circuit diagram of Buck Converter 38
26 Voltage Divider Using Resistor 40
v
LIST OF ABBREVIATION
CPI Cost Performance Index
KPI Key Performance Index
MPP Maximum Power Point
MPPT Maximum Power Point Tracking
P&O Perturb and Observe
PV Photovoltaic
TPI Time Performance Index
VMPP Maximum power point voltage
Voc Open circuit voltage
X-OR Excusive OR
1
CHAPTER 1
INTRODUCTION
1.1 Overview
The development of renewable energy has been an increasingly critical topic in the 21st century with the
growing problem of global warming and other environmental issues. With greater research, alternative
renewable sources such as wind, water, geothermal and solar energy have become increasingly important
for electric power generation. Although photovoltaic cells are certainly nothing new, their use has become
more common, practical, and useful for people worldwide.
The most important aspect of a solar cell is that it generates solar energy directly to electrical
energy through the solar photovoltaic module, made up of silicon cells. Although each cell outputs a
relatively low voltage, if many are connected in series, a solar photovoltaic module is formed.
A photovoltaic module is used efficiently only when it operates at its optimum operating point.
Unfortunately, the performance of any given solar cell depends on several variables. At any moment the
operating point of a photovoltaic module depends on varying insolation levels, sun direction, irradiance,
temperature, as well as the load of the system. The amount of power that can be extracted from a
photovoltaic array also depends on the operating voltage of that array. As we will observe, a maximum
power point (MPP) will be specified by its voltage-current (V-I) and voltage-power (V-P) characteristic
curves. Solar cells have relatively low efficiency ratings.
Thus, operating at the MPP is desired because it is at this point that the array will operate at the
highest efficiency. With constantly changing atmospheric conditions and load variables, it is very difficult
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to utilize all of the solar energy available without a controlled system. For the best performance, it
becomes necessary to force the system to operate at its optimum power point. The solution for such a
problem is a Maximum Peak Power Tracking system (MPPT).
1.2 Power Supply Research
A battery is a source portable electric power. A storage battery is a reservoir, which may be used
repeatedly for storing energy. Energy is charged and drained from the reservoir in the form of electricity,
but it is stored as chemical energy. But, for our design we use capacitor for storing the energy.
In a way, a capacitor is a little like a battery. Although they work in completely different ways,
capacitors and batteries both store electrical energy. Inside the battery, chemical reactions produce
electrons on one terminal and absorb electrons on the other terminal. A capacitor is much simpler than a
battery, as it can't produce new electrons -- it only stores them.
Inside the capacitor, the terminals connect to two metal plates separated by a non-conducting
substance, or dielectric. It won't be a particularly good capacitor in terms of its storage capacity, but it will
work. In theory, the dielectric can be any non-conductive substance. However, for practical applications,
specific materials are used that best suit the capacitor's function. Mica, ceramic, cellulose, porcelain,
Mylar, Teflon and even air are some of the non-conductive materials used. The dielectric dictates what
kind of capacitor it is and for what it is best suited. Depending on the size and type of dielectric, some
capacitors are better for high frequency uses, while some are better for high voltage applications.
1.3 MPPT Research
The Maximum Power Point Tracker (MPPT) is needed to optimize the amount of power obtained from
the photovoltaic array to the power supply. The output of a solar module is characterized by a
performance curve of voltage versus current, called the I-V curve. See Figure 1. The maximum power
point of a solar module is the point along the I-V curve that corresponds to the maximum output power
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possible for the module. This value can be determined by finding the maximum area under the current
versus voltage curve.
1.4 Objective
The objective of the project is to design a Maximum Power Point Tracking (MPPT) charge collecter
which operate with photovoltaic module and produce maximum power to solar power collector. This
component optimized the amount of power obtained from the photovoltaic array and charged the power
supply.
1.4.1 Problem statement
To fight against the global warming and any other problem that related with fossil fuels, most countries
are switching to renewable energy source like sunlight, biomass, hydro and wind. Eventhough some
countries already use renewable energy source, the renewable energy technologies are not appropriate in
some application and location. However, among several renewable energy source, photovoltaic array are
used in many application such as water pumping, battery charging and street lighting. In this application
the load can be demand more power than photovoltaic (PV) system can deliver. Therefore to achieve the
power required, power conversion system is used to maximize the power from PV system.
1.4.2 Requirements
Figure 1: I-V Curve of typical solar
panel
4
MPPT is able to maximize power up to 80W. It also can used to operate up to 20 panel in parallel. The
load used is water pumping. The system has display to show the power.
1.4.3 Safety Feature
All electronic part only consumes 5V. To prevent damage on the solar electronic devices, a regulator is
used to regulate the dc supply to 5V.
1.4.4 Tolerance/Accuracy
The MPPT systems have temperature tolerance of +/-2β°C.
1.4.5 Input/Output Definition
Input is solar power. Output is load.
1.4.6 Operation Environment
This device operate in outdoor when there have sufficient sun light during day time.
1.4.7 Hazardous Level
MPPT system operate outdoor in order to collect the solar power which is all the device expose to
disturbance like temperature, environment and else. The overheated wire connection is possible to cause
the system fail to operate.
1.4.8 Overshoot Protection
The IP56 is used to hold the electronic device of the MPPT system. The wire need casting to protect the
wire from overheating.
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1.5 Scope of work
1.5.1 Academic Review
Before the MPPT project taken out, the background research for the MPPT was collected. MPPT and
photovoltaic cell research need to consider since the MPPT was design according to the solar panel
system. Information and data from the analysis will combine to get the idea how to design and how the
MPPT system will work.
1.5.2 Mathematical Modeling
The maximum power of MPPT system will calculated based on the maximum power from Solar Panel. It
includes the calculation for the system loading effect where the internal resistance can be obtained. The
MPPT circuits also need to calculate the power, voltage and current for the input and output of the load.
1.5.3 Simulation
Circuit will simulate using the Proteus or Pspice Software to ensure whether the installation of the circuit
can be running or not. The circuit will be tested using different sorts of input to get the desired output.
The most important device in this system is Peripheral Interface Controller (PIC). It will control the
whole system and display the load output.
1.5.4 Hardware Realization
After the simulation done, circuit will be construct. The collected power from solar panel will and the
maximum power that can archive will record to ensure it ready to be connected to the circuit. The final
stage to complete this circuit is combined the circuit with the final structure. The IP56 casing will be use
for the safety future.
1.5.5 Testing
6
The Solar Panel will be connected as input to the MPPT system and the motor pump will be used as the
output. The flow of testing process is:
i. Monitoring system test
ii. Temperature control test
iii. Power absorbed test
iv. Electrical safety test
1.5.6 Calibration
Calibration will be done according to an error of the system, which is help to improve the system
accuracy. The device with the known or assigned correctness is called the standard. Then the conceptual
design of MPPT should be achieved.
1.6 METHODOLOGY
1.6.1 Academic Review
Firstly, research about the meaning of the Maximum Power Point Tracking (MPPT) device and its
function with photovoltaic cell will be done. Via internet and other resources, circuit of the MPPT device
will be learned as well as method of how the MPPT device controls the power which will supply directly
to the load. In addition, some useful equations will be reviewed as well so that the modeling can be done
easily.
1.6.2 Mathematical Modeling
The modeling part will divided into three parts. The first part is the photovoltaic cell (also known as solar
cell). Photovoltaic has a method for generating power using solar cells to convert energy from the sun
into the flows of electrons. Solar cells have a complex relationship between solar irradiation,
temperature and total resistance that will produces non-linear output efficiency. Secondly, MPPT system
is used to sample the output of the cells and apply the proper resistance (load) to obtain maximum power
7
for any given environmental conditions. MPPT system will be build according to the desired output and
supply to the desired load.
1.6.3 Simulation
After modeling the desired part of the system, all of the system will be simulated using proper software
(Pspice or Proteus) to ensure that the desired output will be obtained. The software we will use allows for
the division of a stimulated system into numbers of subsystems. This subsystems can be model and test
individually and then interconnected later. This makes it possible to build the physical subsystems such
as the solar panel, MPPT and other system as independent units and verify their proper functionality.
Display blocks and graphs can be attached to any interconnecting line to monitor the corresponding
signal's behavior. The monitored signal can also be written to a workspace variable for further evaluation
and analysis.
1.6.4 Hardware Realization
After all the stimulation, all of the circuit will be constructing according to the designed. In this part, we
are more focusing on the MPPT system, controller and the load. For the solar system, the solar panel
used in our system will provided by School of Engineering and Information Technology. PIC
microcontroller is use in the MPPT system to control the output which will be the supply of the load.
Software for the controller can be developed, deployed, and tested by using C/C++ assembler. For the
circuit side, Printed Circuit Board (PCB) will be used and the circuit drawn as per designed. After all the
circuit is being done, the circuit will place into the appropriate housing or casing which we will use IP56
case and for the cable, we use cable trunking so that our design look need and tidy.
1.6.5 Testing
After all the circuit and hardware have been successfully attached, the device will be tested to know the
performance of each device. First of all, the solar panel will be connected to the MPPT device and
8
monitoring the output of the system which display by the LCD display board. The control system will
control and set the desire output and supply to the load.
1.6.6 Calibration
All the testing and troubleshooting will be doing it in the same time when there is failure and problem
occurs while doing testing. Some calibration will be carry out in order to get the desire output.
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CHAPTER 2
LITERATURE REVIEW
2.1 Solar energy
Solar energy is imperative to support critical energy sources on earth. Basically, it work to grow our food,
light our days, manipulate weather patterns, provide heat, and can be used to generate solar electricity.
Solar electricity relies upon man-made devices such as solar panels or solar cells in order to provide a
source of clean, or we can speak as a low cost renewable energy. The fully system of solar electricity are
involved from the critical part called solar panel. Itβs should be the main part that absorbed the sun energy
then convert it into another energy to ensure the voltage and power are produced. As solar energy
technologies become more advanced, we are able to develop the energy we receive from the sun to
provide a greater, significant amount of our electricity. Being implicit in several characteristic of how
solar panel works make our ability to produce the maximum power are closed.
2.2 The concepts behind solar panel
Solar cells are usually made from silicon, the same material used for transistors and integrated circuits.
The silicon is treated or "doped" so that when light strikes it electrons are released, so generating an
electric current. There are three basic types of solar cell which is Monocrystalline, Polycrystalline and
Amorphous. Monocrystalline cells are cut from a silicon ingot (bar) grown from a single large crystal of
silicon whilst polycrystalline cells are cut from an ingot made up of many smaller crystals. The third type
is the amorphous or thin-film solar cell.
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Table 1: Level of efficiency of different type of material solar panel
Material Level of efficiency %
Monocrystalline silicon 14 to 17
Polycrystalline silicon 13 to 15
Amorphous silicon 5 to 7
We should be familiar with concepts of "Doping", itβs the intended introduction of chemical
elements, with which one can obtain a surplus of either positive charge carriers (p-conducting
semiconductor layer) or negative charge carriers (n-conducting semiconductor layer) from the
semiconductor material. If two differently contaminated semiconductor layers are combined, then a so-
called p-n-junction results on the boundary of the layers.
Figure 2: p-n junction of solar panel
At this junction, an interior electric field is built up which leads to the separation of the charge
carriers that are released by light. Through metal contacts, an electric charge can be tapped. If the outer
circuit is closed, meaning a consumer is connected, and then direct current flows. Finally, metal contacts
on the cell allow connection of the generated current to a load. A transparent anti-reflection film protects
the cell and decreases reflective loss on the cell surface.
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2.3 The Characteristic of Solar Panel
The characteristic is usually different based on the types of solar panel material. For analysis through
characteristic, we always refer to the voltage-current V-I characteristic.
Figure 3: I-V curve of different Solar Panel power
Every model of solar panel has unique performance characteristics which can be graphically represented
in a chart. The graph in Figure 3 is called an βI-V curveβ, and it refers to the moduleβs output relationship
between current (I) and voltage (V) under existing conditions of sunlight and temperature. Theoretically,
every solar panel has multiple I-V curves (several of which are shown above for one particular module)
one each for all the different combinations of conditions that would affect the STC rating parameters
above: temperature, air mass, irradiance and so on. Because of Ohmβs Law (and the equation Power =
Voltage x Current), the result of reduced voltage is reduced power output. The ideal position on any I-V
curve, the sweet spot where we can collect the most power from the module is at the βkneeβ. Thatβs the
maximum power point (MPP), and we can see that its position changes with temperature and irradiance.
The objective for a system to constantly track the P-V curve to keep the operating point as close to the
maxima while energy is extracted from the PV array.
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2.4 Side Effect to the Solar Panel
Basically, we need to construct an experiment while βplayingβ with solar panel as our source energy from
sun ray. The general concept or theory according to the parameters like current-voltage behavior,
maximum power produced from opened-circuit and closed-circuit or the efficiency normally different to
the real world while testing.
2.4.1 Panel Arrangement/ Orientation
Solar panels are installed differently based on our geographic locations throughout the world. The idea
behind this is simple; the sun is in a different place in the sky, so panels need to be directed according to
this positioning. The ideal situation is when the sun is hitting the panels at a perfectly perpendicular angle
(90Β°). This maximizes the amount of energy striking the panels and being produced. The two factors that
such an angle is controlled by are the orientation (North/South/East/West) and the angle of the panels
from the surface of the Earth.
2.4.2 Roof and Panel Pitch
The most application using the solar panel is placed at the highest part of building. The βpitchβ or tilt of
our roof can affect the number of hours of sunlight we receive in an average day throughout the year.
Large commercial systems have solar tracking systems that automatically follow the sunβs tilt through the
day. These are expensive and not necessary to the normal type of application such as 12 Volt output
devices.
2.4.3 Temperature
This is the huge problem always facing to the small component devices. Some panels like it hot but most
donβt. So, panels typically need to be installed a few inches above the roof with enough air flow to cool
them down. As a result the power output will be reduced by between 0.25% (amorphous cells) and 0.5%
13
(most crystalline cells) for each degree C of temperature rise. This reduction in efficiency may be
important to us if we have a high electricity demand to the devices.
2.4.4 Partial Shading
Basically, shade is the enemy of solar power. With poor solar design, even a little shade on one panel can
shut down energy production on all of your other panels. Before we design a system for our devices, weβll
conduct a detailed shading analysis of our roof to reveal its patterns of shade and sunlight throughout the
year. There may be situations where this cannot be avoided, and the effects of partial shading should be
considered as part of energy absorption.
2.5 Perturb and Observe (P&O) Algorithm
Solar cells produce energy by performing two basic tasks: (1) absorption of light energy to create free
charge carriers within a material and (2) the separation of the negative and positive charge carriers in
order to produce electric current that flows in one direction across terminals that have a voltage
difference. Solar cells perform these tasks with their semiconducting materials. The separation function is
typically achieved through a p-n junction. Solar cell regions are made up of materials that have been
βdopedβ with different impurities. This creates an excess of free electrons (n-type) on one side of the
junction, and a lack of free electrons (p-type) on the other. This behavior creates an electrostatic field with
moving electrons and a solar cell is essentially, a large-area diode (Richard, 2006). Researches on
renewable energies have received much attention due to their capability of reducing the fossil fuels usage
and mitigating the environmental issues such as the green house effect and air pollution (Liu and Huang,
2011). Among the renewable energies, the photovoltaic (PV) generation system has become increasingly
important as a renewable source due to its advantages such as absence of fuel costs, low maintenance
requirement and environmental friendliness. However, in PV generation system, the conversion efficiency
is very low, especially under low irradiation, and the amount of the electric power generated by solar cells
varies with weather conditions. Therefore, a maximum power point tracking (MPPT) method is used to
14
maximize the harvested solar energy from the solar panel. In the MPPT system, the system works to find
the maximum power point (MPP) via powerful microcontroller. There are many ways of distinguishing
and grouping methods that seek the MPP from a photovoltaic (PV) generator (Salas et al, 2006). All the
different algorithms has its own pro and cons. In addition, each PV has its own voltage-current (V-I)
characteristics. Figure 4 shows the V-I characteristics of a PV under different irradiance. Figure 5 shows
the P-V photovoltaic characteristics for four different irradiation levels.
Figure 4: I-V Photovoltaic Characteristics for four different irradiation levels.
15
Figure 5: P-V photovoltaic characteristics for four different irradiation levels
From Figure 4 and Figure 5, the MPP can be determined. It is used widely in seeking it using different
algorithms. There are many algorithms in tracking the MPP, for instances, Perturb and observe algorithm,
incremental conductance algorithm, parasitic capacitances, constant voltage control, constant current
control, pilot cell, artificial intelligent method (Algazar et al, 2012).
2.6 Buck Converter
A buck converter is a step-down DC to DC converter. Its design is similar to the step-up boost converter,
and like the boost converter it is a switched-mode power supply that uses two switches (a transistor and
a diode), an inductor and a capacitor. The operation of the buck converter is fairly simple, with
an inductor and two switches (usually a transistor and a diode) that control the inductor. It alternates
between connecting the inductor to source voltage to store energy in the inductor and discharging the