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 flipflop: (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

2

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

3

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 +/-2C.

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.

5

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.

9

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. Its 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.

10

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", its 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.

11

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 I-V curve, and it refers to the modules 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 Ohms 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 knee. Thats 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 playing 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

(90). 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 pitch 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 suns 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

dont. 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, well

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

doped 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

16

inductor into the load. For the purposes of analysis it is useful to consider an idealised buck converter. In

the idealised converter all the components are considered to be perfect. Specifically the switch and the

diode have zero voltage drop when on and zero current flow when off and the inductor has zero series

resistance. Further it is assumed that the input and output voltages do not change over the course of a

cycle (this would imply the output capacitance being infinitely large).

2.6.1 Continuous mode

A buck converter operates in continuous mode if the current through the inductor (IL) never falls to zero

during the commutation cycle. In this mode, the operating principle is described by the plots in figure 4:

When the switch pictured above is closed (On-state, top of figure 2), the voltage across the inductor

is . The current through the inductor rises linearly. As the diode is reverse-biased

by the voltage source V, no current flows through it;

When the switch is opened (off state, bottom of figure 2), the diode is forward biased. The voltage

across the inductor is (neglecting diode drop). Current IL decreases.

The energy stored in inductor L is

Therefore, it can be seen that the energy stored in L increases during On-time (as IL increases) and then

decreases during the Off-state. L is used to transfer energy from the input to the output of the converter.

The rate of change of IL can be calculated from:

With VL equal to during the On-state and to during the Off-state. Therefore, the increase

in current during the On-state is given by:

, t{on} = DT

17

Identically, the decrease in current during the Off-state is given by:

, t{off} = (1-D)T

If we assume that the converter operates in steady state, the energy stored in each component at the end of

a commutation cycle T is equal to that at the beginning of the cycle. That means that the current IL is the

same at t=0 and at t=T (see figure 4).

So we can write from the above equations:

It is worth noting that the above integrations can be done graphically: In figure 4, is proportional

to the area of the yellow surface, and to the area of the orange surface, as these surfaces are

defined by the inductor voltage (red) curve. As these surfaces are simple rectangles, their areas can be

found easily: for the yellow rectangle and for the orange one. For steady

state operation, these areas must be equal.

As can be seen on figure 4, and . D is a scalar called the duty cycle with a value

between 0 and 1. This yields:

From this equation, it can be seen that the output voltage of the converter varies linearly with the duty

cycle for a given input voltage. As the duty cycle D is equal to the ratio between tOn and the period T, it

cannot be more than 1. Therefore, . This is why this converter is referred to as step-down

converter.

18

2.7 Impedance Matching

Maximum power transfer occur when the impedance of the source equals to the load. The maximum

possible power is delivered to the load when the impedance of the load (load impedance or input

impedance) is equal to the complex conjugate of the impedance of the source (its internal or output

impedance). For two impedance to be complex conjugate conjugate their resistance must be equal, and

their reactances must be equal in magnitude but of opposite signs.

Suppose we have a two terminal circuit and we want to connect a load resistance RL such that the

maximum possible power is delivered to the load. To analyze this problem, we go through Thevenin

equivalent circuit as shown in Figure 2.10. The current flowing through the load resistance is given by

=

+ (2.4)

The power delivered to the load is

= 2 (2.5)

Substituting for the current, we have

=

2 + 2

(2.6)

To find the value of the load resistance that maximizes the power delivered to the load, we set the

derivative of with respect to equal zero:

=

2 + 22

2 +

+ 4= 0 (2.7)

Solving for the load resistance, we have

= (2.8)

Thus, the load resistance that absorbs the maximum power from a two-terminal circuit is equal to the

thevenin resistance. The maximum power is found by substituting = into

=

2

4 (2.9)

19

Figure 5.1 : Thevenin Equivalent circuit

20

CHAPTER 3

LIST OF COMPONENTS

3.1 Resistor

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit

element. The current through a resistor is in direct proportion to the voltage across the resistor's terminals.

Thus, the ratio of the voltage applied across a resistor's terminals to the intensity of current through the

circuit is called resistance. This relation is represented by Ohm's law, where I is the current through the

conductor in units of amperes, V is the potential difference measured across the conductor in units of volts,

and R is the resistance of the conductor in units of ohms.

The electrical resistance is equal to the voltage drop across the resistor divided by the current

through the resistor. Resistors are used as part of electrical networks and electronic circuits. Resistor has

their own color code, where the color code is is determine the value and tolerance of the resistor. Figure 6

shows the table on how to read the value and tolerance of resistor using the color code.

21

Figure 6: Resistor Color Code

3.2 Capacitor

The capacitor's function is to store electricity, or electrical energy. The capacitor also functions as a filter,

passing alternating current (AC), and blocking direct current (DC). The capacitor is constructed with two

electrode plates facing each other, but separated by an insulator. When DC voltage is applied to the

capacitor, an electric charge is stored on each electrode. While the capacitor is charging up, current flows.

The current will stop flowing when the capacitor has fully charged. The capacitance of a capacitor is

generally very small, so units such as the microfarad (10-6

F ), nanofarad ( 10-9

F ), and picofarad (10-12

F )

are used. Recently, an new capacitor with very high capacitance has been developed. The Electric Double

Layer capacitor has capacitance designated in Farad units.

Figure 7(a): Electrolytic Capacitors (Electrochemical type capacitors)

Aluminum is used for the electrodes by using a thin oxidization membrane. Large values of

capacitance can be obtained in comparison with the size of the capacitor, because the dielectric used is

22

very thin. The most important characteristic of electrolytic capacitors is that they have polarity. They have

a positive and a negative electrode.

Figure 7(b): Ceramic Capacitors

Ceramic capacitors are constructed with materials such as titanium acid barium used as the

dielectric. Internally, these capacitors are not constructed as a coil, so they can be used in high frequency

applications. Typically, they are used in circuits which bypass high frequency signals to ground. These

capacitors have the shape of a disk. Their capacitance is comparatively small.

3.3 PIC (Programmable Interface Controllers)

A PIC microcontroller is a processor with built in memory and RAM and you can use it to control your

projects (or build projects around it). It has been already mentioned that microcontrollers differs from

other integrated circuits. Most of them are ready for installation into the target device just as they are, this

is not the case with the microcontrollers. In order that the microcontroller may operate, it needs precise

instructions on what to do. In other words, a program that the microcontroller should execute must be

written and loaded into the microcontroller.

Figure 8: PIC (Peripheral Integrated Circuit)

They can be programmed to be timers or to control a production line and much more. They are

found in most electronic devices such as alarm systems, computer control systems, phones, in fact almost

23

any electronic device.PIC Microcontrollers are relatively cheap and can be bought as pre-built circuits or

as kits that can be assembled by the user.

3.4 D flip-flop

The D flip-flop tracks the input, making transitions with match those of the input D. The D stands for data.

This flip-flop stores the value that is on the data line. It can be thought of as a basic memory cell. A D

flip-flop can be made from a set/reset flip-flop by tying the set to the reset through an inverter. The result

may be clocked.

Figure 9: D flip-flop Diagram

The D (Data) flip-flop has an input D, and the output Q will take on the value of D at every triggering

edge of the clock pulse and hold it until the next triggering pulse. The D flip-flop is usually positive edge

triggered.

(a) (b)

Figure 10: D flipflop: (a) Truth Table and (b)Timing Diagram

CLK D Q Condition

0 1 0 Start

Raising edge 1 1 Store 1

0 0 Q No Charge

Raising edge 0 0 Store 0

24

3.5 Operational Amplifier ( Op Amp )

The Operational Amplifier (Op Amp ) can be used in many different ways. The Op-amp has two inputs

an inverting input ( - ) and a non-inverting input ( + ) and one output. A signal applied to the inverting

input will have its polarity reversed on the output. A signal applied to the non-inverting input will retain

its polarity on the output. The gain or amplification of the signal is determined by a feedback resistor that

feeds some of the output signal back to the inverting input. The smaller the resistor, the lower the gain.

Figure 11: Operational Amplifier (Op Amp )

The name operational amplifier was originally adopted for a series of high performance DC amplifiers

used in analog computers. These amplifiers were used to perform mathematical operations applicable to

analog computation such as summation, scaling, subtraction, integrating and essentially any feedback

operation.

25

CHAPTER 4

OPERATION OF ELECTRONIC PART

4.1 Introduction

This part will cover all components used in the MPPT charge controller circuit and its operation. There

will be details of the function of each components used and its operations. The circuit was divided into 3

parts which are solar array, control circuit and lastly the power stage. The MPPT charge controller

referred is shows below.

Figure 12: MPPT Charge Controller Circuit

26

4.2 Solar Array

For the solar array, the model of the solar panel we used is Sharp NE-80E2EA. This solar

module is able to output a maximum power of 80 Watt. The specifications of the solar module are

supplied by the manufacturers datasheet as shown in figure 13 below.

Figure 13: Specifications of solar panel (Sharp NE-80E2EA).

4.3 Controller

The controller circuit consists of voltage follower, an analog inverter, a multiplier, two differentiators,

two comparators, a XOR-gate and a D Flip-Flop.

4.3.1 Voltage Follower

Voltage follower achieved using op-amp. Op-amp is a DC coupled high gain electronic voltages

amplifier with a differential inputs and single-ended output. The function of op-amp is to amplify the

input voltages and produce larger output.

27

Figure 14: Voltage follower connection

In the referred circuit, the array was connected to a voltage divider before fed into the voltage

follower. LM318 op-amp was used as voltage follower. The used of 51k ohm and 200k ohm voltage

divider is to have high impedances input at multiplier as the voltage follower is then connected as the

input of the multiplier. The supply voltage of the op-amp were set to V+ = 5V and V = -5V. The output

voltage of the voltage follower is

V+=R3

R2 + R3Varray

=200k

200k + 51KVarray

= 0.7968

=

= +

= 0.7968

Varray

28

4.3.2 Voltage Inverter

Another application of op-amp was inverting the voltage and fed into the op-amp. The current

array was measured in term of voltage connecting the array with small value of resistor. The input into

the voltage inverter is negative of array current multiply, -IARRAY with the value sensing resistor, Rs. The

output voltage, VOUT of will be to positive value multiplying with resistance R4 and R6 connecting the

op-amp. Then output voltage waveform of the will be the same as the input waveform shape but the value

is invert from negative to positive and also based on value of R4 and R6. The op-amp being used in the

circuit is LM318.

Figure 15: Inverting Op-amp connection

The output voltage of LM318 voltage inverter is;

4=

6

= 0

=6

4

=36 0.47

1

= 16.92

29

The output voltage of inverting op-amp is then fed into the multiplier. The current of the op-amp

was inverted due to have positive value of power at the multiplier.

4.3.3 Analog Multiplier

Analog multiplier is an electronic device that evaluated the product of two analog signals which it

is output. Analog multiplier is use to calculate power of the array by multiplying the array voltage and

the array current. AD633 is an analog multiplier, four quadrants. It includes high impedance, differential

X and Y inputs and high impedance summing input, Z. This analog multiplier was built using differential

op-amps, multiplier and a voltage follower.

Figure 16: Connection of analog multiplier AD633

4.3.4 Differentiators

Another application of op-amp is to differentiate the voltage fed into the op-amp. This application

was achieve connect a capacitor in series with the op-amp and a resistor at the feedback. In the MPPT

circuit referred, the measured power and voltage of the array is approximately differentiated using high

pass filter. The op-amp used as in differentiator circuit is LM318. The connection for power and voltage

differentiator is shown below. It can be seen that the parameter of capacitors, and resistors used in the

differentiator circuit is same. The differentiated value power and voltage of array is measured as the value

is needed to evaluate to track the MPP.

30

Figure 17: Voltage and Power Differentiator Connection

4.3.5 Comparators

The comparators also using op-amp which compares two voltages or currents and switches its

output to indicate which one is larger. From the referred circuit, the outputs of differentiators dV/dt and

dP/dt were fed into the comparator. At the comparators both the differentiated voltage and array was

compared to ground. The op-amp being used as the comparators were LM311. Although an ordinary op-

amp can be used as comparator, there is special integrated circuit intended for use as comparators. LM311

chips are designed for very fast response and arent in the same league as other op-amp.

31

Figure 18: Power and voltage comparators

The comparators will produce output 1 if the input value is greater than zero while it produce zero

if the input value is lower than zero.

4.3.6 XOR gate

In the referred MPPT charge controller circuit, both output of comparators to the XOR gate.

There is pull-out resistors connected parallel in between the comparators and XOR gates. This connection

is to provide additional power to drive the XOR gate. In the pull-out resistor, 4.7k ohm resistor connected

in series with 5V voltage source and shunted in between comparators and XOR gate. The XOR being

used in the circuit was IC7486. Since there were two inputs to the XOR gate, then there will be 4

conditions. The truth table of the XOR gate showing the output of each condition is shown as well as its

connection in the circuit.

Xv Xp output

0 0 0

0 1 1

1 0 1

1 1 0

(b)

(a)

32

(c)

Figure 19: (a) Connection diagram of IC7486, (b) XOR truth table, (c) Connection of XOR gate in

the circuit

4.3.7 D Flip-Flop

Flip-flop is an electronic circuit that has two stable states and thereby is capable of serving one bit of

memory. It usually controlled by one or two signals and/or a gate or clock signal. The output of D-flip-

flop, Q looks a delay of input D. In the referred circuit, the D flip flop that being used is 74HC74 D flip-

flop. The connection to flip-flop is shown below.

Figure 20: 74HC74 D-Flip-flop connection

33

and must be connected high logic (1) to enable the flip-flop to operate where output

was determined by input, D. According to table 2 below, flip-flop will operate if and are set to

HIGH logic.

Table 2: PRE and CLR function table

The output of XOR is connected to flip-flop before fed to switch because to prevent high

frequency switching chattering and to minimize the unavoidable interference generate by the buck

converters switching action [David and Yan, 2000]. This interference occurs immediately after the clock

transition and is over before the next, so latch never samples it.

34

CHAPTER 5

SYSTEM MODELING

5.1 Input and output definition

The input of our design MPPT system is the DC power supply from the solar panel. The output of this

system is the output voltage to the load supplying 80 W to the DC motor. The power that is harvested

from solar panel is maximized using the MPPT system by using P&O algorithm. Basically, to have the

maximum power transfer to the load, an impedance matching circuit design is required. Hence, our

overall design can be divided into four simple stages as in figure 21. Figure 21 shows the input solar

panel is fed into the MPPT system and impedance matching to have the desired output at the load.

Figure 21: Simple block diagram for overall system.

5.2 Detail design and drawing

The overall design of MPPT is built based on logic components such as, voltage follower, voltage

inverter, analog multiplier, differentiators, voltage comparators, X-OR gate, and D-flip flop. These

components are used to track the MPP by using the P&O algorithm. The DC-DC buck converter is used

to step down to 12V for the load use. The overall design schematic is as follows,

Solar Panel MPPT Impedance

matching Load- DC

motor

35

Figure 22: Full schematic diagram for MPPT system and Buck Converter

5.3 Operation of MPPT system using P&O algorithm

MPPT system tracks the maximum power point of the solar panel and supplies it to the buck converter.

The overall operation of the operation is simplified as in flow chart in Figure 23. Figure 23 shows the

flow of tracking the MPP of solar panel.

Figure 23: Flow chart for MPP tracking

Voltage

follower Differentiators

Differentiators

Comparator

Comparator Inverting

Amplifiers Multiplier X-OR

D-flip flop Switch

Varray dV/dt

dP/dt Parray

36

Figure 24: The Circuit operation chart.

The solar panel will exhibit the PV curve as in Figure 24. Refer to the P-V curve in Figure 24, the P&O

algorithm is implemented using the MPPT controller circuit. By referring to the Maximum Power Point

(MPP), the voltage array is increased or decreased by charging or discharging of capacitors.

At point A, V

37

now is negative and

is positive while P is increasing toward MPP. The switch is closed and

capacitor discharged resulting in V decreasing toward VMPP.

In conclusion, the circuit operation is tabulated in Table 3. Table 3 shows the simplified circuit operation

of tracking MPP by P&O algorithm.

Table 3: Circuit operation of MPPT by P&O algorithm.

Condition

Comparator output X-OR

output

Switch Voltage

XV XP

VVMPP

Positive Negative 1 0 1 Close Decreases

Negative Positive 0 1 1 Close Decreases

5.4 Buck converter operation

The buck converter circuit is shown in Figure 25, basically it is built up of three main components,

namely diode, inductor and capacitor. The diode is blocking diode which is connected in series with the

solar array to prevent the reverse terminal current. In the circuit, the diode is assumed to be ideal. The

capacitor, C is used to control the voltage of the array. When the operating voltage is smaller than the

voltage at the maximum power point, VMPP, the capacitor will charge to increase the voltage and vice

versa.

Buck converter is a step-down DC-DC converter. The DC input voltage or the current can be

regulated to desired DC output. The output of buck converter is smaller than the input voltage. By

controlling the switch, the output voltage can be controlled.

38

Figure 25: Circuit diagram of Buck Converter

5.5 Buck converter detail design

Assumed input is 20V.

=

= 12

=12

20

= 0.6

Minimum Inductor value;

= 1

2

Let switching frequency, f=40Khz

= 1 0.6

2 40

Where =

2

= 80

=122

80

= 1.8

39

=0.4 1.8

80

= 9

To be continuous current,

So, we choose 1mH to be used in the circuit.

Capacitor value;

1

8

2

Assumed 1% of voltages ripple,

0.4

8 1 0.01 (40)2

3.125

So, we choose .

5.6 ADC scaling in PIC

ADC scaling can be done by determined the supply voltage and input voltage of the component.

If the voltage input value was high, the current voltage level on the supply should estimate the storage

energy left. The charge level should be alert, because it will indicate user weather the device should be

cut off beyond the threshold or drops below a certain level.

For the ADC scaling with PIC, the maximum input voltage should be noted, to ensure the voltage

will be measure is higher or lower than the input voltage for PIC. In this case, easiest way is to use

voltage divider using resistor.

Assuming you want to measure the automotive battery voltage. Typically, the battery voltage will

be 20 V. For safety reason, let's assume we design for 25V maximum input voltage (25% safety factor).

To accomplish this, we'll use 5 resistors of 4.7k each a potentiometer can also be used to set it correctly.

40

Figure 26: Voltage Divider Using Resistor

The input to the ADC will be 5v when voltage input is present 20v, thus the input voltage has been scaled

by factor of 1/5. The ratio is obtained from the voltage divider.

PIC input voltage = (v)R1

(R1+R2+R3+R4+R5)

= (25v)4.7k

(4.7k + 4.7k + 4.7k + 4.7k + 4.7k)

= 5v

By using VDD(5V) as the ADC reference, the ADC reading will be 1023 when the ADC input is 5V. To

obtain the actual reading, the following equation is used,

= 20( )

1024

0

R3

4.7k

R2

4.7k

Actual_Input

R4

4.7kPIC_ADC

R1

4.7k

R5

4.7k

41

CHAPTER 6

FABRICATION

6.1 Prototype picture

6.2 Comments

The product is produced incompletely. There are parts that we could not acquire, such as the LCD display

and the analog multiplier. The failure in obtaining these two components make the overall system could

not perform the MPPT tasks as planned.

42

CHAPTER 7

KEY PERFORMANCE INDEX

7.1 Time performance index

Key performance index (KPI) is used to evaluate the activitys success or failure. KPI includes the time

performance index (TPI) and the cost performance index (CPI). A unity for both TPI and CPI indicates a

perfect or optimum performance done by the team. However, TPI which exceeding 1 means the delay in

the project, for the same case, CPI exceeding 1 simply indicates that the expense is over-budgeted. Table

4 shows the weekly TPI by Greentech Engineering in conducting the MPPT project.

Table 4: Weekly TPI for MPPT project

Week W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13

TPI 1.00 1.08 1.34 1.53 1.39 1.54 1.69 1.64 1.46 1.59 1.70 1.80 1.43

Table 5: Week number in dates

WEEK DATE

W1 5MAR-9MAR

W2 12MAR-16MAR

W3 19MAR-23MAR

W4 26MAR-30MAR

W5 2APR-6APR

W6 9APR-13APR

W7 16APR-20APR

W8 23APR-27APR

W9 30APR-4MAY

W10 7MAY-11MAY

W11 14MAY-18MAY

W12 21MAY-25MAY

W13 28MAY-1JUN

W14 4JUN-8JUN

43

7.2 Gantt Chart

44

7.3 Comments on TPI and Gantt Chart

Referring to TPI in Table 4, the TPI is greater than 1 which means there is a delay in the project

conducted. For example, taking Week 7 as an example, Week 7 has a TPI of 1.69 which means there is a

69% delay in our project. At the same time, by referring to the Gantt chart in section 7.2, Week 7 shows

the task of system modeling. For the task system modeling, the planned time is 7 days but our group spent

16 days in doing it. The failure in completing the task on time leads our group to incomplete design at the

final time.

Table 6: Simplified schedule of project

Tasks Duration Start date End date

1.1 Project Requirement 1 5/3/2012 5/3/2012

1.2 Background search 7 5/3/2012 15/3/2012

1.3 Conceptual design 7 8/3/2012 13/3/2012

1.4 Proposal preparation 10 5/3/2012 20/3/2012

1.5 Proposal presentation 1 20/3/2012 4/4/2012

2.1 System Modeling 7 4/4/2012 24/4/2012

2.2 Simulation 3 24/4/2012 27/4/2012

2.3 Analysis 3 24/4/2013 27/4/2013

2.4 Detail design and drawing 8 30/4/2012 25/5/2012

3.1 PCB 5 28/5/2012 30/5/2012

3.2 Mechanical fabricatin 7 30/5/2012 30/5/2013

3.3 Assembly 4 30/5/2012 1/6/2012

5.2 User Manual 2 1/6/2012 1/6/2012

5.3 Final Product 5 1/6/2012 1/6/2012

45

7.4 Cost performance index

No. Description Supplier Receipt

No. Date Qty. Unit Price Total

1 IRFZ44N MOS-N-FET-e Genius Electronic Co. 71934 28.05.12 1 4.00 4.00

2 PIC16F877A MPU 1 28.00 28.00

3 36K 1/4W CARBON FILM RESISTOR 1 0.20 0.20

4 0.47R(R47)2W METAL OXIDE FILM RESISTOR 1 1.20 1.20

5 40 PINS CONTACT-STRIPS 1 3.60 3.60

6 8 PINS IC SOCKET 4 0.60 2.40

7 56uF 25Vdc ELECTROLYTIC CAPS 1 1.20 1.20

8 100uF 25Vdc ELECTROLYTIC CAPS 1 0.50 0.50

9 100uF 16Vdc ELECTROLYTIC CAPS 1 0.40 0.40

10 VERO BOARD 64X146MM (2 1/2"X3 1/2")-OT-PCB-2LN RADIOTRONIC SDN. BHD. 01054510 28.05.12 3 1.30 3.90

11 CERAMIC CAPACITOR 104P 50V 2 0.30 0.60

12 DIODE 1 0.30 0.30

13 12.288M CRYSTAL 1 2.00 2.00

14 RESISTOR 1/4W 16 0.20 3.20

15 I.C SN74LS86 2 2.50 5.00

16 I.C 4 4.50 18.00

17 I.C.7805 / MC78M05C/ANT78M05 1 1.50 1.50

18 IC LM311N 2 2.00 4.00

19 3800uH INDUCTOR Genius Electronic Co. 71958 29.05.12 1 7.00 7.00

20 22pF CERAMIC CAPS 2 0.40 0.80

21 CAPACITOR 100uF 16V RADIOTRONIC SDN. BHD. 2049772 01.06.12 2 0.30 0.60

22 CAPACITOR 100uF 25V 2 0.30 0.60

23 I.C 7812 1 1.50 1.50

24 I.C 7805 / MC73M05C/ANT78MOS 1 1.50 1.50

25 DC12 ROCKER SWICTH MS-1366BND12 1 2.40 2.40

46

26 MSR-5-2X 3P ROCKER SW 1 3.00 3.00

27 42/0.15X2C CABLE 1 1.90 1.90

28 9V BATTERY SNAP NH-553/T 1 0.50 0.50

29 44X50X14MM HEAT SINK Genius Electronic Co. 71975 01.06.12 1 4.50 4.50

30 25X30X13MM (TQ220) HEAT SINK 1 1.50 1.50

31 BANANA (SOLDER TYPE) PLUG Genius Electronic Co. 71974 01.06.12 4 1.00 4.00

32 BINDING POST (S) TERMINAL 4 2.00 8.00

TOTAL 117.80

=.

= .

The overall CPI is low due to incomplete of project, such that the LCD and casing IP56 is not bought.

47

CHAPTER 8

CONCLUSION AND FUTURE WORK

8.1 Conclusion

The final product is completed but it is not working as expected. The lacks of components lead to the

incomplete design of our product. Although our product does not run successfully, we obtain a lot of new

knowledge from this project. Despite of gaining theoretical knowledge, we as well as acquire soft skills

such as co-operation among team members, communications skills and so on. We gain experiences that

will be useful in our future time and we apply the theoretical world to the practical life. The main reason

the work could not complete is the inappropriate time planning for each tasks. The critical path is not

done properly and punctually. Secondly, the incomplete and insufficient of background research has

interrupted our group in detail designing of MPPT system. And lastly the most critical problem in

completing the project is the self-discipline among the group members.

8.2 Future work

The non-renewable energy is running out nowadays, such as fossil fuels are depleting on earth. Therefore,

changing to renewable energy source is a necessity. Solar energy will be the choice and it is easily

acquired. However, most solar panel has low efficiency, so the MPPT system will help maximizing the

power absorbed from the solar panel.

48

REFERENCE

Adedamola O., 2006. Thesis of Analysis, Modeling and Simulation of Optimal Power Tracking of

Multiple-Modules of Paralleled Solar Cell Systems. The Florida State University.

Algazar M. M., AL-monier H., EL-halim H., Salem M. (2012). Maximum Power Point Tracking Using

Fuzzy Logic Control. Electric Power and Engery Systems, 19, 21-28.

Chaitanya T., Saibabu C., and Kumari J.S., 2011. Modeling and Simulation of PV Array and its

Performance Enhancement Using MPPT (P&O) Technique. International Journal of Computer

Science & Communication Networks, Vol.1(1).

Chia S.L., Ahmad M.H., Ossen D.R. (2004). Impact of solar radiation on high-rise built form in tropical

climate. Department Of Architecture, Faculty Of Built Environment, University Of Technology

Malaysia.

David C. H. and Yan H. L., 2000. Simple maximum power point tracker for photovoltaic arrays.

Electronic Letters, Vol. 36, No. 11.

Liu Y. H., Huang J. W. (2011). A fast and low cost analog maximum power point tracking method for

low power photovoltaic systems. Solar Energy, 85, 2771-2780.

Moorthy M. (2010). Performance of solar air-conditioning system using heat pipe evacuated tube

collector. National Conference in Mechanical Engineering Research and Postgraduates Studies,

564-572.

Muzathik A. M., Wan Nik W. B., Samo K. B. & Ibrahim M. Z. (2010). Hourly global solar radiation

estimate on a horizontal plane. Journal of Physical Science,21(2), 51-66.

Richard Corkish, Deo Prasad (2006) Integrated Solar Photovoltaics for Buildings. Journal of Green

Building: Spring 2006, Vol. 1, No. 2, pp. 63-76.

Salas V., Olias E., Barrado A., Lazaro A. (2006). Review of the Maximum Power Point Tracking

Algorithms for stand-alone Photovoltaic Systmes. Solar Energy Materials & Solar Cells, 90, 1555-

1578.

Retrieved from http://www.elexp.com/t_resist.htm on 1st June 2012

49

APPENDIX

Company Logo

50

Schematic Drawing of MPPT

51

CCS C compiler

52

Proteus

53

Flow chart of P&O algorithm

There are several algorithms used to build MPPT system, it varies from cost and efficiency. The one we

are using here is Perturb and Observe Method (P&O) and Incremental Conductance. The reason we using

a combined algorithm is that P&O alone may not be so accurate of determining the Maximum Power

Point. There are some drawbacks in P&O, such as, the rapidly varying of irradiance.

Basically, P&O algorithm states that when the operating voltage of the PV panel is perturbed by a

small increment, the resulting change in power P is positive, then we are going in the direction of MPP

and we keep on perturbing in the same direction. If the P is negative, we are going away from the

direction of MPP and the sign of perturbation supplied has to be changed.

Figure shows the plot of module output power versus module voltage for a solar panel at a given

irradiation. The point marked as MPP is the Maximum Power Point, the theoretical maximum output

obtainable from the PV panel. By considering A and B as two operating points, we can move towards the

MPP by providing a positive perturbation to the voltage. On the other hand, we can move toward MPP

via point B when there is a negative change in power.

54