tracking solar panel

OPTIMAL SOLAR TRACKING SYSTEM

MOHAMAD KASYFI BIN SAMSUDDIN

UNIVERSITI TEKNOLOGI MALAYSIA

“I hereby declare that I have read this research report and in my opinion this

research report is sufficient in view of scope and quality for the purpose of awarding

a Bachelor’s Degree of Electrical Engineering (Electronics)”

Signature : _____________________________

Name of Supervisor : EN. ABD RAHIM B. ABD RAHMAN

Date : 30 APRIL, 2010

OPTIMAL SOLAR TRACKING SYSTEM

MOHAMAD KASYFI BIN SAMSUDDIN

Submitted to the Faculty of Electrical Engineering

in partial fulfillment of the requirement for the degree of

Bachelor in Electrical Engineering (Electronics)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

APRIL 2010

ii

DECLARATION

I declare that this thesis entitled “OPTIMAL SOLAR TRACKING SYSTEM” is the

result of my own project except as cited in the references. The thesis has not been

accepted for any degree and is not concurrently submitted in candidature of any other

degree.

Signature : ………………………………………

Name : MOHAMAD KASYFI BIN

SAMSUDDIN

Date : 30 APRIL 2010

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DEDICATION

To my beloved mother and father

iv

ACKNOWLEDGEMENT

First I would like to express my sincere gratitude to my supervisor, En. Abd.

Rahim Abd. Rahman. Under his supervision, many aspects regarding this project

have been explored and with the knowledge, idea and support received from him,

this thesis can be presented in the time given.

My appreciation also goes to my family who has been so tolerant and

supports me all these years. Thanks for their encouragement, love and emotional

supports that they given to me. Thanks to my senior and all my friends who helped

me directly or indirectly in completing this projects. Not forgetting, grateful

appreciation is also extended to the lab technician of UTM’s Laboratory who gave

me great assistance during the process in accomplishing PSM one and two.

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ABSTRACT

Solar energy is the least polluting and most inexhaustible of all known energy

sources. The sun bathers the earth with more energy each minute then the world

consumes in one year. In Malaysia, the sun intensity does not vary by season. It is a

suitable place to develop the solar cell system. Fossil fuels are a relative short-term

energy source and to overcome this problem the uses of alternative sources such as

solar energy are becoming more wide spread. To make solar energy more efficient,

the solar panel system must be maximized. This project is regarding the development

of a sun tracking solar system. This system is a simple tracking solar system using a

dc motor and light sensor. The solar tracking system used in this method could

increased the power collection efficiency by developing a device that can tracks the

sun to keep the panel at a right angle to its rays. As the plane of the solar panel is

always maintained normal to the sun's rays, maximum power is generated by the

array. A solar tracking system is designed, implemented and experimentally tested.

The design details and the experimental results are shown promising result.

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ABSTRAK

Tenaga suria adalah tenaga yang tidak menghasilkan pencemaran dan

diketahui tidak akan habis berbanding sumber-sumber tenaga lain. Tenaga matahari

yang dipancarkan ke atas bumi pada setiap minit sudah melebihi tenaga yang

diperlukan di bumi dalam setahun. Di Malaysia, cahaya matahari tidak dipengaruhi

oleh musim. Ini menjadikan, Malaysia sebuah tempat yang sesuai untuk

membangunkan system berasaskan tenaga suria. Sumber fosil sebenarnya adalah

sumber yang terhad dan untuk mengatasi masalah ini, penggunaan tenaga alternatif

seperti tenaga suria telah berkembang. Bagi menghasilkan penggunaan tenaga suria

yg lebih berkesan, sistem panel suria bagi memaximumkan keberkesanan perlu

dibangunkan. Laporan ini menunjukkan potensi dan kelebihan dengan menggunakan

sistem penjejek ringkas yang menggunakan motor arus terus dan pengesan cahaya.

Kaedah ini meningkatkan kadar pengumpulan tenaga suria dengan membangunkan

peralatan yang boleh menjejak matahari dan memastikan panel suria sentiasa

menghadap matahari. Reka bentuk secara mendalam dan keputusan analisis ada

ditunjukkan.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF SYMBOLS xiii

LIST OF APPENDICES xiv

1 INTRODUCTION 1

1.1 Background of Project 1

1.2 Objective 2

1.3 Scope of Project 3

1.4 Outline of Thesis 4

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2 LITERATURE RIVIEW 5

2.1 Fundamental of Photovoltaic System 5

2.1.1 Photovoltaic 5

2.1.2 The Photovoltaic Effect 6

2.2 Efficiency 8

2.3 Types of System 10

2.4 Previous Study 11

2.4.1 Microcontroller Automatic Sun Tracker 11

2.4.1.1 System Description 11

2.4.1.2 Control Implementation 13

2.4.1.3 Test result 14

2.4.2 Implementation Solar Tracking System 16

2.4.2.1 System Description 16

2.4.2.1 Solar Tracker Verification and Testing19

2.5 Control System 20

2.6 Operation of 555 timers 21

2.6.1 Pin Configurations of the 555 Timer 21

2.6.2 Monostable Operation of the 555 Timer 23

3 METHODOLOGY 25

3.1 Development Process 25

3.1.1 Phase 1 26

3.1.2 Phase 2 26

3.1.3 Phase 3 28

3.2 Electronic control system 29

3.3 Hardware development 30

3.4 Electronic Design 30

3.4.1 Sensor Control Tracking System 31

3.4.2 Photo-Sensor 31

3.4.3 The 555 Timer 33

3.4.4 Relays 34

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3.4.5 Relay Operation 34

3.4.5.1 Relay Energize (ON) 34

3.4.5.2Relay De-Energized (OFF) 34

3.4.6 DC Motor 35

3.5 Mechanical Design 36

3.5.1 Frame Work 37

3.5.2 Mechanical Operation 37

3.5.2.1 Stage 1 38

3.5.2.2 Stage 2 38

3.5.2.3 Stage 3 38

4 RESULT AND ANALYSIS 39

4.1 Introduction 39

4.2 Indoor Analysis 40

4.2.1 Result at stage 1 40

4.2.2 Result at Stage 2 41

4.2.3 Result at Stage 3 42

4.2.4 Time Line Analysis Base on Indoor Analysis.44

4.3 Outdoor Analysis 46

5 CONCLUSION AND RECOMMENDATION 48

5.1 Conclusion 48

5.2 Recommendation 49

REFERENCE

APPENDICES

x

LIST OF TABLE

TABLE NO. TITLE PAGE

3.1 List of component 30

3.2 LDR operation 32

3.3 The 555 timer operation 33

4.1 Result 1 40

4.2 Result 2 40

4.3 Result 3 41

4.4 Result 4 41

4.5 Result 5 41

4.6 Result 6 42

4.7 Result 7 42

4.8 Result 8 42

4.9 Result of outdoor analysis 47

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 The emission of electron from metal plate 6

2.2 The photovoltaic effect in the dark place 7

2.3 The photovoltaic effect in the bright place 7

2.4 The photovoltaic effect in the bright place 8

2.5 System circuit diagram 12

2.6 Block diagram 12

2.7 Voltage against position graph 12

2.8 Circuit diagram 13

2.9 MPP at illumination level A 14

2.10 MPP at illumination level B 15

2.11 Voltage controlled power conversion 15

2.12 Current controlled power conversion 15

2.13 Solar tracker control circuit 17

2.14 H-bridge motor control 18

2.15 Basic software design flowchart 18

2.16 Signal generated when one LDR was under shadow19

2.17 Signal generated when both LDR in same illumination level19

2.18 Negative feedback control system 20

2.19 The comparator in the 555 timer 23

2.20 The sample input and output pulse 24

3.1 The circuit diagram 27

3.2 The block diagram 29

3.3 LDR 32

3.4 The PVC 32

3.5 The SPDT relay circuit diagram 35

xii

3.6 The SPDT relay 35

3.7 The DC motor 36

3.8 The cassis of the system 37

xiii

LIST OF SYMBOLS

R - Resistor

C - Capacitor

Vcc - Voltage supply

xiv

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Mechanical Data of 555 Timer 53

B LDR Data Sheet 54

C NE555 Data Sheet 57

D DC Motor Data Sheet 64

E Songle Relay 65

CHAPTER 1

INTRODUCTION

1.1 Background of Project

Solar power is an alternative technology that will hopefully lead us away

from our petroleum dependent energy sources. The major problem with solar panel

technology is that the efficiencies for solar power systems are still poor and the costs

per kilo-watt-hour (kwh) are not competitive, in most cases, to compete with

petroleum energy sources.

. In Malaysia, the sun is always directly overhead and its intensity do not

varies by season. This give a lot more advantage for us to use solar power compare

with the place that have season. There are two most common type systems that

always use for small building generated system:-

1. The solar thermal system

2. The photovoltaic system

The solar thermal system operate by convert the radiant energy of the sun into

heat then use that heat to provide useful electric energy.

On other hand, the photovoltaic system converts directly the sun radiant into

useful electric energy, which can be used as most electrical energy in used today.

2

Solar power (photovoltaic) systems are a sustainable way to convert the

energy of the sun into electricity. The expected lifetime of a system is 25-30 years.

This shows how efficient is this system even it is quite expensive to install this

system at the beginning.

Amount of power produced by a photovoltaic panel depends upon the amount

of sunlight it is exposed to. In other word, more light means more power. In order to

capture more light produce by sun, the photovoltaic panel must constantly orient

itself to the sun location. When the photovoltaic panel does not intercept as much

light as it can, it will not produce as much power as it can.

Fixed photovoltaic panel do not aim directly to the sun due to the constant

motion of earth. As the result, the power produce by the system is less then it capable

producing. To overcome this problem, the tracking system can be installed in order

that the panel continually adjusts so that the panel is always aim directly at the sun.

As the result, Photovoltaic panel are able to collect the maximum amount of sunlight

and produce the most power possible.

1.2 Objective

The objective of this project is to develop tracking mechanism for

photovoltaic panel to maximize the generation of electrical energy. The objective of

the project is

to develop the system that can constantly tracking the sun.

3

1.3 Scope of Project

The system consists of a mechanical design and circuit development. The

tracker system will follow sun movement from east to west. The movement

controlled by the dc motor that using 12volt supply.

Mechanical part: The panel or the place that the solar cell hook up is designed that it

can move from right to left or from left to right. The panel movement is controlled by

string attached to the dc motor. The panel is designed to operate with single axis

only. Two sensors are placed at the east side and west side. Both sides also have reset

switch to limit panel movement.

Electronic Part: The circuit function is to control the motor movement determined by

the location of the sun ray. The 555 timer is used to control the system. Input control

is using LDR. The sensitivity of the circuit is control by potentiometer. Dc motor is

connecting to the relay and the circuit function is to trigger the relay to made dc

motor move.

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1.4 Outline of Thesis

This thesis consists of five chapters. In the first chapter, it will discuss about

the objective and scope of this project along with a summary works. While Chapter 2

will discuss more on literature reviews that have been done.

In Chapter 3, the discussion will be on the methodology, mechanical part and

electronic part of this project. The result and discussion will be presented in Chapter

4. Last but not least, Chapter 5 discusses the conclusion of this project and future

work that can be done

CHAPTER 2

LITERATURE REVIEW

2.1 Fundamental of Photovoltaic System

Photovoltaic panel are made of the natural element which becomes charged

electrically when subjected to sunlight. Photovoltaic is the direct conversion of light

into electricity at the atomic level. The panel works on the principle of the

photovoltaic (PV) effect. For solar cells, a thin semiconductor wafer is specially

treated to form an electric field, positive on one side and negative on the other.

2.1.1 Photovoltaic

When light energy strikes the PV cell, electrons are knocked loose from the

atoms in the semiconductor material and start travel from the PV cell, through

electronic circuit to the load. Then, they return to the PV cell where the silicon

recaptures the electrons and the process is repeated. The photovoltaic itself is a p-n

junction, which through the process of electron dropping and this produces a current

in proportion to the solar radiation. If electrical conductors are attached to the

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SUNLIGHT

positive and negative sides, forming an electrical circuit, the electrons can be

captured in the form of an electric current and produce electricity. This electricity

can then be used to power a load, such as a light or a tool [1].

Figure 2.1 The emission of electron from metal plate

Figure 2.1 illustrating the emission of electrons from a metal plate, requiring energy

gained from absorb sunlight radiation to be more than the work function of the

material.

2.1.2 The Photovoltaic Effect

The photovoltaic effect is the basic physical process through which a PV cell

converts sunlight into electricity .Sunlight is composed of packets of solar energy.

These sunlight radiations contain different amounts of energy that correspond to the

different wavelengths of the solar spectrum. When photons strike a PV cell, they may

be reflected or absorbed, or they may pass right through. The absorbed photons

generate electricity. The photovoltaic cells generally consist of two thin regions, one

above the other, N-type and P-type. This two region structure, called a p-n

junction. The collection of light-generated carriers by the p-n junction causes a

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P-type

N-type

When in the dark

LIGHT

N-type

P-type

Under the sun light

movement of electrons to the n-type side and holes to the p-type side of the junction.

When open circuit, carriers are prevented from leaving the solar cell, then the

collection of light-generated carriers causes an increase in the number of electrons on

the n-type side of the p-n junction and a similar increase in holes in the p-type

material. This separation of charge creates an electric field at the junction which is in

opposition to that already existing at the junction. Under short circuit conditions, the

minority carrier concentration on either side of the junction is increased and the drift

current, which depends on the number of minority carriers, is increased. In

equilibrium (in the dark) both the diffusion and drift current are small [2].

Figure 2.2 The photovoltaic effect in the dark place

Figure 2.3 The photovoltaic effect in the bright place

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LIGHT

N-type

P-type

Figure 2.4 The photovoltaic effect in the bright place

2.2 Efficiency

On a bright, sunny day, the sun's rays give off approximately 1,000 watts of

energy per square meter of the planet's surface. If we could collect all of that energy,

we could easily power our homes and offices for free. However, in practically the

maximum allowed by the law of physics is between 30% and 40%. The efficiency of

photovoltaic cells can be very tricky to figure out and many of the companies that

produce them take different routes when manufacturing their products. Different

companies will use different materials and as the technology improves, the efficiency

of the solar paneling options will also improve. There are basically 3 different types

of solar panels on the market today, each of which has a different efficiency rating.

The following are the 3 types and their efficiency ratings [3]:

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Monocrystalline Silicon – manufactured using a single crystal of silicon

which has been cut into a prescribed shape, this type of solar panel has a 13%

conversion rate, meaning that it converts 13% of the captured sunlight into

electricity [4].

Polycrystalline Silicon – these are less expensive and have a lower

conversion rate because of the multiple crystal manufacturing process. This

increases internal resistance between the silicon crystals. The conversion rate

of these panels is around 12% to 12½% [5].

Thin Film Amorphous Silicon – probably the cheapest solar panel to produce

and the least efficient at a rate of only 6% to 8%. More suited for use in

cooler and tropical climates, this type of solar panel is not very efficient in

arid, hot climates [6].

Other then the material that use to crate solar cell its self, there are few factor that

will affect the energy efficiency. The output will be less at:-

In cloudy condition

The module is in the shade

Pointed away from the sun

In space, the output is more higher due to the solar radiation is much stronger

compare at the earth. Approximately, the power density is around 1365 watt per

square meter.

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2.3 Types of System

Basically, there are three main systems that commonly use in photovoltaic

system. It’s come with several configurations for difference use.

1. Directly Connected System

a. The system work without battery storage.

b. The load connected to the system operates in synchronization with

sunlight.

c. Usually an over current protection device is added for safety purpose.

d. Typical application are:-

i. Ventilation fan.

ii. Water pumping.

iii. Calculator.

2. Stand Alone System

a. The system may have battery storage or emergency backup supply to

provide power when the sun is not available.

b. Commonly use in a remote area where there is no power-lines.

c. This type of system need to have charge regulator to prevent battery

overcharging or over discharging.

d. Typical application are:-

i. Remote home.

ii. Outdoor lighting

iii. Solar car

3. Utility Interactive System

a. This system consist neither battery storage nor an emergency backup

system.

b. This system connected with the utility grid.

c. When the sunlight not available it has battery storage

d. When the sunlight and battery storage out, the power will be supply

by utility power system.

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2.4 Previous Study

There are two reviews that use as example before build optimal solar tracking

system. Both review using difference method to track the sun position.

2.4.1 Microcontroller Based Automatic Sun Tracker Combine with a New

Solar Energy Conversion Unit by F. Huang, D. Tien and James Or.

In 2004 F. Huang, D. Tien and James Or had complete the paper about

microcontroller based automatic sun tracker combined with a new solar energy

conversion unit. This sun tracker had developed in order to increase the efficiency of

the solar panel. The control system that developed base on automatic sun tracker that

used was implemented with a dc motor and a dc motor controller. The energy

conversion unit in this tracker system that created had an array of solar panel, a step-

up chopper, a single-phase inverter, an ac main power source and a microcontroller

based control unit. This tracker was not uses any sensor to detect the location or the

angle of the sun. In this tracker, Maximum Power Point (MPP) detector was use. In

simple, the array of solar was set up as sensor. It was operated to find the angle that

can provide the highest solar energy and assume that was the most direct angle with

the sun. The operation was started by search MPP location. The position and value of

MPP will set as reference for find new angle.

2.4.1.1 System Description

The system was designed at 500W using 10 solar panel connected in series

and in parallel. The output voltage output collected was 40 to 100 volt. The system

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was design to disable if the voltage drops below 40 volt. Set-up chopper was used to

convert the voltage collected to a higher voltage. Insulated Gate Bipolar Transistor

(IGBT) was then used as inverter to convert the dc voltage from the chopper main

supply.

Figure 2.5 System circuit diagram

The system was designed to active when the panel voltage higher than 40

volt. There also had function to set the time interval for the panel to rotate. The time

interval used can be set 5 or 10 minutes. The system was designed to rotate at P

position first then move toward P2 position. The system compares the panel voltage

that was collected. When voltage panel at P2 was greater than P position, the panel

was set to move further until the voltage panel less than previous panel.

Figure 2.6 Block diagram

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Figure 2.7 Voltage against position graph

Figure 2.8 Circuit diagram

2.4.1.2 Control Implementation

MPP detection and the control of power conversion unit were controlled by

single circuit. The input of the control circuit was the feedback signal from the panel

voltage and the output was a current source to drive the power transistor in the

chopper circuit.

At the beginning, S1 was kept close and S2 was kept opened. The time

constant, T = RC was designed to be 10 milisecond. The two darlington transistor

TIP 112 and TIP 117 function as voltage to current source converter. The increases

of the voltage at the base of the TIP 112 result in increase of the current at the

collector of the TIP 117. After that, the microcontroller start obtained the information

of the panel voltage.

Once the detection mode complete, the conversion mode will be initiated.

The voltage from detection mode was set as reference in conversion mode. In

conversion mode, S1 and S2 kept open. TIP 112 and TIP 117 were now functioning

as switching mode. The panel voltage was sample every 5 micro second and this

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voltage (actual panel voltage) was compare with the reference voltage that collected

from detection mode.

When the actual voltage was higher than the reference, the logic high was

produce at the microcontroller. When the actual voltage falls below the reference

voltage, the logic low was produce. The logic low then switches off the power

transistor. The MPP condition was controlling the on-off duration of the power

transistor.

2.4.1.3 Test result.

The subject was test with two solar panels connected in series. In this review,

there were 4 test results collected from the project. First and second results were

about the waveform of the panel voltage, current and power of illumination level.

The other two were about the voltage across the solar panel when the panel was

controlled.

Figure 2.9 MPP at illumination level A

a) Panel voltage, 2Ov/div (top)

b) Panel output power, 5OW/div (middle)

c) Panel output current, 1Ndiv (bottom)

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Figure 2.10 MPP at illumination level B

a) Panel voltage, 2Ov/div (top)

b) Panel output power, 5OW/div (middle)

c) Panel output current, 1Ndiv (bottom)

Figure 2.11 Voltage controlled power conversion

Figure 2.12 Current controlled power conversion

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2.4.2 Implementation of a Prototype for a Traditional Solar Tracking System

by Nader Barsoum.

In 2009, Nader Barsoum had developed a system to implementation of a

prototype for a traditional solar tracking system. This prototype had developed in

order to increase the efficiency of the solar panel. The project was constructed using

sensor part, microcontroller part, motor part and mechanical part. The solar tracker

used photodiode as a sensor, PIC16F84A and dc motor. The PIC was controlled the

H-bridge or motor controller which consist of four transistor. The PIC was

programmed to receive the input from LDR and send the output to control the motor.

2.4.2.1 System Description.

The H-bridge was constructed using four transistor 2N2222, four diodes

1N4148 and two 10K resistor. There also additional component, variable resistor

bank used to reduce motor rotation. The system was designed to obtain its data from

LDR. When light falls on its surface, the LDR produce low resistance. The data

collected then send to PIC and process. Then, the PIC gives the output to control the

motor movement. In simple, when both LDR receive equal illumination, their

resistance level will be the same. With an error margin +/- 10 point, the PIC will not

generate any output. However, when LDR receive difference illumination level, the

PIC will generate output to control the motor [13, 14, and 15].

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Figure 2.13 Solar tracker control circuit

18

Figure 2.14 H-bridge motor control

Figure 2.15 Basic software design flowchart

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2.4.2.2 Solar Tracker Verification and Testing

The testing was conducted to verify the functionality of LDR. There were two

situations that used in this testing. First situation when one LDR cover by shadow

and other when both LDR were under shadow.

Figure 2.16 Signal generated when one LDR was under shadow

Figure 2.17 Signal generated when both LDR in same illumination level

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2.5 Control System.

This tracking system use feedback control system. There are two main types

of feedback control systems: negative feedback and positive feedback. In a positive

feedback control system the set point and output values are added. In a negative

feedback control the set point and output values are subtracted. As a rule negative

feedback systems are more stable than positive feedback systems. Negative feedback

also makes systems more immune to random variations in component values and

inputs. The control system that use was negative feedback system due to stability and

immune to random value.

Figure 2.18 Negative feedback control system

Base from figure 2.18, the position reference actually is sun position. When sensor

detect sun location, it will give signal to run the motor (Pin) to move the panel to sun

location. Position output is representing the actual position of the photovoltaic panel.

If the position output is not directly with position reference, Pin is not equal to zero

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and this will give the signal to move until Pin equal to zero or mean position

reference equal with position output [10].

2.6 Operation of 555 timers.

The 555 Timer IC is an integrated circuit (chip) implementing a variety of timer

applications. Depending on the manufacturer, the standard 555 package includes

over 20 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin.

Basically the 555 has three operating modes:

Monostable mode: in this mode, the 555 functions as a "one-shot".

Applications include timers, missing pulse detection, bounce free switches,

and touch switches, frequency divider, capacitance measurement, pulse-width

modulation (PWM) [6].

Astable - free running mode: the 555 can operate as an oscillator. Uses

include LED and lamp flashers, pulse generation, logic clocks, tone

generation, security alarms [6].

Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop [6].

http://en.wikipedia.org/wiki/Monostable

http://en.wikipedia.org/wiki/Astable

http://en.wikipedia.org/wiki/Oscillator

http://en.wikipedia.org/wiki/LED

http://en.wikipedia.org/wiki/Bistable

http://en.wikipedia.org/wiki/Schmitt_trigger

http://en.wikipedia.org/wiki/Flip-flop_(electronics)

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2.6.1 Pin Configurations of the 555 Timer

Ground (Pin 1): this pin is connected directly to ground.

Trigger (Pin 2): This pin is the input to the lower comparator and is used to set

the latch, which in turn causes the output to go high.

Output (Pin 3): Output high is about 1.7V less than supply. Output high is

capable of Isource up to 200mA while output low is capable of Isink up to

200mA.

Reset (Pin 4): This is used to reset the latch and return the output to a low state.

The reset is an overriding function. When not used connect to V+.

Control (Pin 5): Allows access to the 2/3V+ voltage divider point when the 555

timer is used in voltage control mode. When not used connect to ground through

a 0.01 uF capacitor.

Threshold (Pin 6): This is an input to the upper comparator.

Discharge (Pin 7): This is the open collector to Q14 in figure 4 below.

V+ (Pin 8): This connects to Vcc the NE555 version is 3V - 16V DC.

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2.6.2 Monostable Operation of the 555 Timer

Figure 2.19 `The comparator in the 555 timer

The circuit is called a bistable because it is stable in two states: output high

and output low. It is also known as a 'flip-flop’. Base from figure, the 555 timer is

composed of the voltage comparators, the flip-flop and the transistor for the

discharge. The monostable mode (one shot) which requires only two external

components, Ra and C. Time period is determined by T period = 1.1 (Ra C).

Three resistors are connected with the inside in series and the power supply

voltage (Vcc) is divided in 3. 1/3 of power supply voltage is applied to the positive

input terminal of the comparator (COMP1) and the voltage of 2/3 is applied to the

negative terminal of the comparator (COMP2).

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When the voltage of the trigger terminal (TRIGGER) is less than 1/3 of the

power supply voltage, the output of the flip-flop becomes high level and a flip-flop is

set. When the voltage of the threshold terminal (THRESHOLD) is more than 2/3 of

the power supply voltage, the R terminal of the FF becomes H level and an FF is

reset.

The reset input (555 pin 4) overrides all other inputs and the timing may be

cancelled at any time by connecting reset to 0V, this instantly makes the output low

and discharges the capacitor. If the reset function is not required the reset pin should

be connected to +Vcc [8].

Other than that, the threshold input (555 pin 6) monitors the voltage across

C1 and when this reaches 2/3 Vcc the time period is over and the output becomes low.

At the same time discharge (555 pin 7) is connected to 0V, discharging the capacitor

ready for the next trigger. The time period of the pulse given by, T period = 1.1 (Ra C)

[9].

Figure 2.20 The sample input and output pulse

CHAPTER 3

METHODOLOGY

3.1 Development Process

The objective of this project is to develop the control system that can manipulate

the solar panel to move constantly with sun movement. In order to complete this

objective, the method and technical strategies implied is the most important

disciplined need to look at. Therefore, this project is divided into phase by phase.

The main objective for divided into phase is to detect any problem at early stage. It is

much more organized to do the job one by one according to their respective phase.

There are two phase of development that use to complete the project:-

Phase 1- Mechanical Design Process

Phase 2- Electronic Control System

Phase 3- Combination and Beta Test

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3.1.1 Phase 1

Mechanical design is one of the major phases in the development of the solar

tracking system. This part contributes to what the solar panel control would look like.

The skeleton of the panel is designed and constructed in this phase. Few sketches

have developed and one of the best had been chosen. The purpose of the skeleton is

to provide a place to mount the electronics component such as:-

DC motor

Sensor (LDR)

Push button

Potentiometer

Solar cell

String

3.1.2 Phase 2

Electronic Control development process is the main part of the project. The

second phase involves the development of control system. Base from the circuit of

Monostable Operation of the 555 timer, the circuit that can control motor movement

had been developed. There are few adjustments and some modification, so that the

circuit can operate accordingly. After that, numerous tests on the designed circuit are

performed on the prototyping board. The circuit is then constructed on PCB board

using Portel Software. There are two circuits that have been designed for this control

system:

Circuit A

Circuit B

27

Circuit A and B are similar but each circuit controls different part in the system.

Circuit A control east side and circuit B control west side. Below is the diagram of

one part of the circuit.

Figure 3.1 The circuit diagram

28

These circuits consist of:-

Sensor (LDR)

Push button switch

20k ohm potentiometer

C1 (0.01 microfarad)

C2 (3.3microfarad)

R1 (47k ohm)

R2 (1M ohm)

Relay 12v core- Single Pole Double Throw (SPDT)

IC 555 timer

DC motor

12 volt power supply (Lead Acid Rechargeable Battery).

3.1.3 Phase 3

In order to combine the circuit part A and B with mechanical system, the

circuit test need to be to make sure it will follow the sun constantly. Few adjustments

and modifications need to be done before the system can work smoothly. Every

condition and situation needs to be looked carefully.

29

3.2 Electronic control system.

Figure 3.2 The block diagram

The block diagram shows how the electronic control system was developed

and how they communicate with each other. There are 10 block of the block diagram

and each block represents the component with its function to control the system.

There are 2 blocks that represent the sensor that are used to detect the position of the

sun. One at the east and the other at the west similar to the sun movements, that

move from east to west. That sensor will provide signal to the 555 timer when the

sun position is varied. The timer 555 will decide the motor movement base on the

input that they received from the sensors. After the DC motor moves the panel, the

30

sensor will reconfigure the sun position and give new signal to timer 555. The

process is repeated until both sensors give the right position of sun.

3.3 Hardware development.

The hardware development can be divided into electronic design and

mechanical design. Both design related to each other and equally important.

3.4 Electronic Design

The tracking of photovoltaic panels is controlled or regulated among other

thing by electronic controller circuit.

Table 3.1: List of component

Component Quantity

NE555 timer 2

20K potentiometer 2

Cadmium Sulfide Photo resistor 2

1M ohm resistor 2

47k ohm resistor 2

0.01 micro farad capacitor 2

3.3 micro farad capacitor 2

SPDT Relays nominal 12v coil 2

Push button 2

Lead Acid Rechargeable Battery 12 volt 1

DC motor 1

31

3.4.1 Sensor Control Tracking System.

In this project, the system is built using photo-sensor, electronics driven

control system(IC 555 timer) and DC motor. The radiation receive from the sun light

on the photo-sensor acts as the input to the controlling system and the angular

displacement caused by the DC motor is based on the input receive by photo-sensor.

The system supplied with 12volt (dc) supply.

3.4.2 Photo-Sensor

A pair of light dependent resistor (LDR) is used as photo-sensor for this

tracking system. Both LDRs act as input and sense the sun position. The resistance

LDR falls with increasing light intensity. When the LDR receive light the resistance

becomes low and this will input low to the 555 timer. However, when LDR in the

dark, LDR resistance become high and this will give input high to the 555 timer. The

555 timer trigged only when it receives voltage that below 1/3 of Vcc. In this case

the voltage to trig the IC 555 timer must be below 4volt.

A polyvinyl chloride (PVC) tube with 6cm length is placed on each photo-

sensor to minimize the effect of sunlight diffusion. The diffuse radiation that is not

directly from the sun will be blocked by the tube. This will increase the sensitivity of

the photo-sensor.

The LDR1 is placed at the east part of the solar panel and the LDR2 is placed

at the west part of the solar panel. Both will act as a sun position detector. Then the

signal goes to the 555 timer.

32

2.5

cm

6cm

900

Sun light

Figure 3.3 LDR

Figure 3.4 The PVC

Table 3.2: LDR operation

LDR condition Resistance Voltage Input Voltage Output

LIGHT LOW HIGH LOW

DARK HIGH LOW HIGH

33

3.4.3 The 555 Timer.

The 555 timer is one of the most important components in this electronic

circuit. 555 timer is the heart of the solar tracking system. 555 timer in this design

has 8 pins and every pin have their own function. It acts as the central data

processing unit, responsible for the fundamental operation of logic. In this design, the

555 timer will pick up the input from LDR and give output to the DC motor. The

timer chip are wired for monostable “one shot” operation. It will give output high

when receive low voltage from LDR. The timed interval is controlled by a single

external resistor and capacitor network.

When the trigger input falls below the trigger level, the flip-flop is set and the

output goes high. If the trigger input above the trigger level and the threshold input is

above the threshold level, the flip-flop is reset and the output is low. The reset input

can override all other input and can be used to initiate a new timing cycle. When

reset goes low, the flip-flop is reset and the output goes low.

The output from the 555 timer will go to the relay before to DC motor. In this

design, there are two circuit that use to control the motor and each circuit have the

555 timer. Each timer receives input from difference LDR and this two 555 timers

connect to relay and both relay connect to the same motor.

Table 3.3: The 555 timer operation

RESET TRIGGER

VOLTAGE (volt)

THRESHOLD

VOLTAGE (volt)

OUTPUT

Low - - Low

High <1/3 Vcc - High

High >1/3 Vcc >2/3 Vcc Low

High >1/3 Vcc <2/3 Vcc As previous

34

3.4.4 Relays.

Relays are used as remote control switch. Relays which come in different

sizes, rating, and application, are used as remote control switches. Basically, relays

are remote control electrical switches that are controlled by another switch, such as

power train control module. Relays allow a small current flow circuit to control a

higher current circuit. In this circuit, SPDT Relay with 12v coil is use. SPDT stand

for single pole double throw. A common terminal connects to either of two others.

Including two for the coil, such a relay has five terminals in total. All relays operate

using the same basic principle. The control circuit has a small control coil while the

load circuit has a switch. The coil controls the operation of the switch.

3.4.5 Relay Operation.

There are two type of operation in relay:

Relay energized (ON)

Relay de-energized (OFF)

3.4.5.1 Relay Energize (ON).

Current flowing through the control circuit coil creates a small magnetic field

which causes the switch to close. The switch, which is part of load circuit, is used to

control an electrical circuit that may connect to it. Current now flow through pins to

load.

35

3.4.5.2 Relay De-Energized (OFF).

When current is stops flowing through the control circuit, the relay become

de-energized. Without the magnetic field, the switch opens and current is prevented

from flowing through pins. The relay now OFF

In this tracking system, both relay set as ground when not function. When

sensor detects sun movement, it will give signal to the 555 timer. Then, the 555 timer

will trig relay to control the motor.

Figure 3.5 The SPDT relay circuit diagram

Figure 3.6 The SPDT relay

36

3.4.6 DC Motor.

In this project, DC motor is used to move the solar panel. The DC motor is

connecting with string and attach to the panel. When motor rotate, it will move the

panel and that movement will relocate the angle of the LDR sensor. The LDR sensor

will send back the signal of sun location and the motor stopped when the right angle

was founded. It all depends from the input provided by sensor.

DC motor type that use in this project is from SPG30-20k series. This type of

series use 12 volt input and available to produce maximum 1.1 watt power as

mention in data sheet. A DC motor required at least one electromagnet. This

electromagnet switches the current flow as the motor turns, changing its polarity to

keep the motor running. The motor rotate from positive terminal to negative

terminal.

Figure 3.7 The DC motor

37

3.5 Mechanical Design.

The combination of all components will create the control circuit. Every

component has own rule in the system. However, the system needs the chassis to

complete the prototype. The chassis developed is used to place the electronic

component at the right place and also to make it move freely from east to west and

back to east again.

3.5.1 Frame Work.

There is little part that critical that influences the movement of the chassis of

the solar panel. There are push buttons that limit the cassis movement. There also a

string that connects the motor with panel where the circuits are placed. The panel

also places the sensor to detect sun position. The DC motor is placed at the center

bottom of the cassis. The panel movement will be control by DC motor via timing

belt. The LDR will give information about panel position and the direction the motor

should move. The limit switch connects to pin number four and act as a limit for

panel movement. S1 connect to circuit 1 at east side and S2 connect to circuit 2 at

west side. S1 part represent east part and S2 part represent west.

Figure 3.8 The cassis of the system

38

3.5.2 Mechanical Operation

The operation of this chassis can be divided into three categories:

Stage 1

Stage 2

Stage 3

3.5.2.1 Stage 1

Stage one consist of three situations:

When S1 doesn’t detect any light and S2 detect the light. The motor will

move to west.

When S2 doesn’t detect any light and S1 detect the light. The motor will

move to east.

Both movement will stop when touch the switch SW1 or SW2.

3.5.2.2 Stage 2

Stage two consists of two situations:

Motor will stop when both LDR in dark.

Motor will stop when both LDR in sun light.

3.5.2.3 Stage 3

Stage three happen when the panel at the west limit and touch SW2 or at east limit

where it touch SW1.

At east limit: when S2 detect the light, motor move to west.

At west limit: When S1 detect the light, motor move to east.

CHAPTER 4

RESULT AND ANALYSIS

4.1 Introduction

This chapter discussed on the outcome of the project. The analysis

and experiment are being conduct in order to test the functionality and

performance of the tracking system. The analysis is Optimal Solar Tracking

System is done in two different situations:-

Indoor analysis

Outdoor analysis

Both have different objectives. The indoor analysis is just trying to

figure out the functionality of the system toward light. In this analysis, the

source of light are torch light and the result obtain must agree with the

theory. The motor movements are observed so it will show the result as

expected before the analysis at actual working field is conducted.

The outdoor analysis is done in actual field. The objective is to test

the functionality of the system toward sun position. The position in degree

is taken and compare between sun position and solar panel position.

36

4.2 Indoor Analysis

These analyses follow the mechanical operation. It consist three stage

same as mechanical operation.

4.2.1 Result at stage 1

Table 4.1: Result 1

When

S1(1),S2(0)

VCC PIN 2 PIN 3 Motor Movement

555 timer 1 12v 1.0v 10.0v Move to east

555 timer 2 12v 8.0v 0.0v Move to east

Table 4.2: Result 2

When

S1(1),S2(1)


555 timer 1 12v 7.9v 0.0v Move to west

555 timer 2 12v 1.6v 9.0v Move to west

1 = High light intensity

0 = Low light intensity

Base from the table, when light strike at LDR S1, the input in pin two

of the 555 timer 1 become low. This produce high output at the 555 timer 1

and move the motor to the east. Same happen when LDR S2 receives the

light. The difference between this two are the motor movement. The motor

movement control by input from LDR sensor.

37

Table 4.3: Result 3

When

S1(1),S2(1)


555 timer 1 12v 1.03v 0.0v Motor don’t move


Table 4.4: Result 4

When

S1(1),S2(1)






These tables are proving of function reset pin in IC 555 timer. When

the panel move and touch the push button that place at the limit range of

panel, the reset function at pin 4 of 555 timer will trigged. This function is

active low, mean when it receives voltage below 0.7 volt, the function

trigged.

4.2.2 Result at Stage 2

Table 4.5: Result 5

When

S1(1),S2(1)




38

Table 4.6: Result 6

When

S1(0),S2(0)




1 = High Light Intensity

0 = Low Light Intensity

In this stage 2 analyses, the LDR sensor both uncover to same light

intensity. This analysis objective is to observe whether the system can stop

moving when the solar panel perpendicular with sun position. Beside,

observe what happen to the system at night.

4.2.3 Result at Stage 3

Table 4.7: Result 7

When

S1(1),S2(1)


555 timer 1 12v 8.3v 0.0v To West

555 timer 2 12v 0.7v 10.0v To West

Table 4.8: Result 8

When

S1(1),S2(1)


555 timer 1 12v 0.1v 10.0v To east

555 timer 2 12v 8.7v 0.0v To east



39

In this stage, the analysis is about the control system that already at

the limit switch but the receiver the light form the other side. For example,

the panel already moves until west limit and the system stop moving due to

reset function. However, went sun rise again from east, the LDR S1

received the light and that will move the motor to the east. The reset

function not influences the system because the system that actually reset is

the 555 timer 2. The LDR S1 only trigged the 555 timer 1. The same thing

happened if the opposite side tested.

40

4.2.4 Time Line Analysis Base on Indoor Analysis.

Figure 4.1 Time line from no light to both LDR receive light

41

Figure 4.2 Time line from motor on to motor stop due limit switch to

motor on

42

Figure 4.3 Experimental set up

4.3 Outdoor Analysis

Outdoor analysis is to prototype of optimal solar tracking system in

actual situation. The angle of sun position is collected from software that

simulated the position of sun. However, the simulations use Kuala Lumpur,

Malaysia as reference place. Assume that sun position at UTM skudai,

Malaysia have the same sun position with Kuala Lumpur, the data analysis

are collected from 6 a.m to 7 p.m.

43

Table 4.9: Result of outdoor analysis

Time 6 7 8 9 10 11 12 1 2 3 4 5 6 7

Sun Position

(degree)

0 15 30 45 60 75 90 105 120 135 150 165 170 180

Angle

perpendicular

with solar

panel

(degree)

45 45 45 45 70 85 90 100 110 135 135 135 135 135

Figure 4.4 The line chart of outdoor analysis

The line chart shows the different of actual sun position with the

position that detect by the system. The limits of the system are limited at 45

degree and 135 degree. Even the sun going more than 135 degree or less

than 45 degree, the system cannot follow more than the limit angle. There

also other things that influence the panel movement such as shade area

produce by cloud, building and other thing.

0

20

40

60

80

100

120

140

160

180

200

6:0

0A

M

7:0

0A

M

8:0

0A

M

9:0

0A

M

10

:00

AM

11

:00

AM

12

:00

AM

1:0

0A

M

2:0

0A

M

3:0

0A

M

4:0

0A

M

5:0

0A

M

6:0

0A

M

7:0

0A

M

Sun Position

Angle perpendicular with solar panel

CHAPTER 5

CONCLUSION AND RECOMMENDATION

5.1 Conclusion

The objective of the project has been achieved. The Optimal Solar

Tracking System was able to constantly follow the sun movement. To

conclude, the system design that use in the project can brings a lot of

function and other application. Still using the design, with a little bit

modification such as change the sensor to temperature sensor, the system

that tracks the heat can develop. Other application such as tracking signal

also can use and develop from this sample electronic design. The

knowledge and skill from this project will give more experience for student

in electronic field.

45

5.2 Recommendation

There are still a lot of space for improvement and enhancement for

this Optimal Solar Tracking System. Optimal Solar Tracking System covers

a large field which required creativity, talent and dynamic mentality to fully

optimize the technology, knowledge and inspiration of the nature. The

prototype of solar panel is a mechanical design while the sensor used was

LRD. The mechanical design of thesis of the system can only operate in

single axis only. In order to increase the efficiency and responsive of the

system, double axis should be used.

The DC motor in this project should be charge to move slowly

movement because the sun does not move really fast. The angle of

movement also should be increased in order to let the time of solar cell

orient with sun much longer.

46

REFERENCE

1) Ng Seah Tian(1992), Optimal Solar Tracking, FKE.

2) Tan Khong Boon (2001), Optimal Solar Tracking, FKE.

3) Eric Anderson, Chris Dohan, Aaron Sikora. (2003) Solar Panel Peak

Power Tracking System, Worcester Polytechnic Institute.

4) Sophie Gledhill, Oliver Nast Hartley, Keith Heasman, Richard Rusell,

Nigel Manson. (2003).High Effecciency monocrystalline Silicon Solar

Cell on B-Doped FZ and Ga-Dope CZ. Alcobendas, Mandrid, Spain.

5) Richard Stephenson. (2007) Fundamental Properties of Solar Cell

and Paste for Silicon Solar Cell. United State of America.

6) Rochs. (2004). Thin Film Amorphous Silicon Solar Cells.

7) Texas Instrument, Incorporate [SLFS022,E][M],NE555,SA555,SE555

(Rev E), Texas Instrument Incorporated, United State of America.

8) Phill Semiconductor (1998) NE555 and NE556 application

47

9) What is the 555 timer? [online]. Available : http://www.electronics-

tutorials.com/devices/555.htm.

10) G.F. Frankin, J.D. Powell, and A. Emami-Naeini. Feedback Control

of Dynamic System, Addison-Wesly Publishing Company, 1995.

11) K. Harada and Gen Zhao, “ Controlled Power Interface Between

Solar Cells and AC source,” IEEE Trans on Power Electronic, No.4

Oct. 1993 p.654-62

12) R.M Hilloowala and A.M. Sharaf, ‘” A rule based fuzzy logic

controller for a PWM inverter in photo-voltaic energy convsion

scheme,” in Conf. Rec. of the IEEE Industry Applications Society

Annual Meeting, New York, 1992, V01.1,p.762-9.

13) Inoue, Seiichi, hardware of the PIC16F84A, 2008.

http://www.interq.or.jp/se-inoue/e_pic2.htm accessed jan, 2009

14) Wilmshurst, Tim. (2007), Designing Embededded Systems with PIC

Microcontrollers, Ch. 2,pg 32, Elsevier

15) Steven, Fred. (1997). Getting started with PIC microcontrollers, Ch.

1, pg 5-6. A. L. Stevens

http://www.electronics-tutorials.com/devices/555.htm

http://www.electronics-tutorials.com/devices/555.htm

http://www.interq.or.jp/se-inoue/e_pic2.htm

48

APPENDICES

tracking solar panel

Documents