1. 1
A Project Report on
SOLAR TRACKER FOR SOLAR PANEL
Submitted By
Mukesh Choudhary[T120223066]
Neeraj Bani [T120223067]
Prashant Kumar [T120223077]
A Seminar report submitted as a partial fulfilment towards term VI of
T.E (Electronics & Telecommunication)
Savitribai Phule Pune University
Guide
Mrs. Sushma Wadar
Department of E&TC Engineering
Army Institute of Technology, Dighi , Pune – 411015
2014-2015

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C E R T I F I C A T E
This is to certify that
Prashant Kumar
Neeraj Bani
Mukesh Choudhary
Of Army Institute of Technology, Dighi, Pune
Have submitted Project Seminar report on
SOLAR TRACKER FOR SOLAR PANEL
As a partial fulfilment of Term-VI for award of degree of Bachelor of
E&TC from Savitribai Phule Pune University during the
Academic Year 2014-2015
Project Guide H.O.D
Mrs. Sushma Wadar Mrs.Surekha K.S

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ACKNOWLEDGEMENT
We would like to express our heartfelt gratitude to Mrs. Shusma Wadar , who is
our supervisor, for her constant guidance in the implementation of this project.
We must particularly thank her for commitment and unrelenting effort to see
us do all the assignments appertaining to this project and finally we can say we
had done.
Again, special thanks to providing us with MSP430 microcontroller together
with the Launchpad which was the very core of my project embedded software
Section.
We would also like to thank H.O.D and all the staff members’ and our colleagues
for their cooperation and support during the collection of materials and also
during our Project. All of your sup
Port has motivated us in many instances. All of the experience has been
educating, humbling and very nostalgic
Thank you all.

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ABSTRACT
The project involves design and implementation of an automatic microcontroller
based solar tracker system expected to be used in photovoltaic conversion
panels. The proposed single axis solar tracker device functions to ensure the
optimization of the photovoltaic panel in accordance with the real position of
the sun. The operation of experimental model of the device is based on a DC
motor which is intelligently controlled by a dedicated drive unit that moves a
mini PV panel according to the signals received by a microcontroller from two
simple but efficient light sensors. The performance and characteristics of the
solar tracker device are experimentally analyzed.

5. 5
Index
Abstract
CHAPTER TITILE PAGENO.
1. INTRODUCTION …………………………………….....[6-7]
1.1 General Background
1.2 Problem Statement
1.3 Project Justification
1.4 Objectives
2. LITERATURE REVIEW……………………………….[8-15]
2.1 Introduction
2.1.1 Types of Solar Trackers and Solar Tracking Techniques
2.1.2 Single Axis Solar Tracking System
2.1.3 Dual Axis Solar Tracking System
2.1.4 Active Solar Tracking
2.1.5 Passive Solar Tracking
2.1.6 Review of Solar Tracking Methods
2.2 A Review of Solar Tracking Methods
2.2.1 Introduction
2.2.2 Solar Tracking in Relation to Rotation and Revolution of the Earth
2.2.3 Nature of Solar Irradiation and the Solar Constant
2.2.4 Sunlight
2.2.5 The Solar Constant
2.2.6 Fixed and Tracking Collectors
2.2.7 Fixed Collectors
2.2.8 Tracking Collectors: Improved Efficiency
3. BLOCK DIAGRAM / FLOW CHART ………………[16-23]
3.1 Light Sensor Theory and Circuit of Sensor Used
3.2 Block Diagram
3.3 Graphical user interface
3.4 Flow chart
3.5 Algorithm
4. METHODOLOGY ……………………………………[ 24 ]
5. ADVANTAGES AND DISADVANATES……………[ 25 ]

6. 6
6. SCOPE OF IMPROVEMENT………………………..[ 26 ]
7. CONCLUSION ………………………………………..[ 27 ]
REFERENCES……………………………………………..[ 27 ]
ABBREVIATIONS AND ACRONYMS…………………[27-28]
APPENDIX………………………………………………..[28-31]

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Chapter 1
INTRODUCTION
1.1 General Background
Today’s world has increasing demands for energy by the day, which is against
the continuous reduction in existing resources of fossil fuels and ever growing
concern regarding environmental pollution. It’s therefore needless to say that
this has pushed mankind to explore new technologies for production of
electrical energy, using clean, renewable sources such as solar and wind power.
A prominent non-conventional renewable energy source is solar energy which
provides great prospect for conversion into electrical power, which in turn
ensures an important part of the electrical energy needs of the planet.
Photovoltaic (PV for short) is the conversion principle employed in conversion
of solar light into electricity. Using solar tracking technique, yield from solar
panel can be increased by 30%-60% unlike in stationary or fixed installations
which if we assume silicon is the material used to build the PV panels, then the
system is only about 24.5% efficient .
1.2 Problem Statement
A solar tracker device has a wide range of applications to improve harnessing of
solar isolation. The problem posed thus is to implement a system that is capable
of improving solar power production by 30-40%. A microcontroller is used to
implement the control circuit which in turn positions a motor used to orient the
solar panel optimally.
1.3 Project Justification
The aim of this project is ensure that sunlight rays are falling perpendicularly on
the solar panel to give the maximum solar energy which is harnessed into
electrical power with the maximum energy being between the period of
1200Hrs to 1400Hrs with the peak around midday when the sun is almost
directly above the solar panel and so minimum energy is used to move the solar
panel, further increasing the efficiency of the tracker. This project seeks to
address the challenge of accurate, low power as well as economical

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microcontroller based solar tracking system that can be implemented using the
allocated time and resources so as to track the relative motion of the sun in the
sky during daylight and to save the much needed power, sleep at night. An
algorithm is implemented to solve the problem of motor control which is then
written into C.
2 program on Code Composer Studio IDE for MSP430G2553 microcontroller.
Readily available and economical tools will be used to implement the project.
1.4 Objectives
The project seeks to satisfy the following objectives
I. Design a system to track solar UV light for solar panels
II. Accurately identify and measure the altitude angle from sunrise to
sunset for Pune.
III. Commonly called the Green City under the Sun.

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CHAPTER: - 2
LITERATURE REVIEW
2.1Introduction
Among the renewable energy sources is electrical solar energy from the Sun can
be harnessed using solar panels or solar cells to convert solar irradiation into
electrical current. Most photovoltaic cells employ photoelectric effect. This is a
process by which electrons are emitted from some materials, such as a metal,
as a result of being struck by photons. Some substances, such as selenium, are
particularly susceptible to this effect and if used in solar cells, they can
generate some electric potential through photoemission.
Sun rays come in form of UV-light, a form of electromagnetic radiation and once
they fall of solar panel surface made of materials such as silicon, the irradiation
is absorbed and converted into electrical energy through photo emission.
Maximum absorption occurs when the solar panels and solar cells directly face
the Sun, so that the sun’s rays fall perpendicularly on the absorption surface.
This absorption and conversion may not be optimal given that the solar panels
and solar cells are mounted in fixed positions usually on rooftops with slants.
For viable solar energy generation using single installation, its efficiency has to
be improved and therefore various solar tracking methods are devised to closely
track sun movement during the day.
2.2 Types of Solar Trackers and Solar Tracking Techniques
Modern solar tracking methods can be classified into the following categories:
2.2.1: Single Axis Solar Tracking System
This is method is usually used for solar trackers aimed to be used in the tropics
where the focus is to track the angle of altitude (angle of tilt) of the sun along a
single axis. A single linear actuator is used, such as a motor to drive the panel
according to sun movements. A set of two LDRs on opposite sides of the solar
panel may be used to measure the intensity of the solar irradiation by measuring
the voltage drop across them which is then compared by a drive circuit until the
two LDR voltages are equal and the motion of the panel is stopped. This way,
the solar panel is always oriented, normally to sun irradiation

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2.2.2: Dual Axis Solar Tracking System
This method is mainly designed for localities outside the tropics or areas beyond
10°N and 10°S of Equator. In this technique, both angle of azimuth and angle of
Tilt of the solar tracker are used to track the sun movements throughout the year.
Consequently, a set of two actuators, usually motors is used to move the solar
panel accordingly by receiving voltage control signals from a set of four LDRs (two
on opposite sides of solar panel) and when the voltage drop on all the four LDRs is
equal then the panel is experiencing the maximum solar irradiation and therefore
the motion stops. This ensures the solar panel is at right angles with sunlight at all
times
Figure 1 Single Axis Solar Tracking System
Figure 2 Dual Axis Solar Tracking System

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2.2.3: Active Solar Tracking
This technique involves the continuous and constant monitoring of the sun’s
position throughout daytime and when tracker is subjected to darkness it stops or
sleeps according to its design. This can be done using of light sensitive sensors, such
as photo resistors(LDRs) whose voltage output are input into a microcontroller
which then drive actuators (motors) to adjust the solar panels position.
2.2.4: Passive Solar Tracking
This method involves trackers that determine the Sun’s position by means of a
pressure imbalance created at two ends of the tracker. This imbalance is caused by
solar heat creating gas pressure on a low boiling point compressed gas fluid that is
driven to one side or the other which then moves the structure.
2.3 A Review of Solar Tracking Methods
2.3.1: Introduction
As stated above, there is an urgent need for better solar tracking technologies
to be developed to harness vast amounts of electrical solar energy in large scale
to cater for the ever growing power demand. Of concern too is the reduction in
the environmental pollution due to use of fossil based fuels. To construct a cost
effective, efficient and effective solar tracking system, it is necessary to
understand the rotation and revolution of the Earth with respect to the locality
in question so as to know the specification of the solar tracker to be constructed.
Since any solar tracker follows the motion of the sun in the sky, it is very
necessary to understand rotation & revolution of the. Earth, solar irradiation
and efficiency of tracking systems which will be shown in later in this project.
2.3.2: Solar Tracking in Relation to Rotation and Revolution of the Earth
The Earth rotates about its own axis taking 24 hours to complete one rotation of
360 degrees and at the same time it revolves around the sun in a year of 365¼ days
or 366 in a leap year. Revolution takes place in an elliptical orbit called the ecliptic.
In addition to the revolution of the. Earth, it is observed that the relative position of
the midday Sun at different times of the year varies. The inclination of the sun from
the earth is referred to as the solar altitude angle.
This is the vertical angle between the projection of Sun’s rays on the horizontal plane
and direction of sun’s rays passing through the point. Usually this is estimated to
be a decline of 23½ degrees northwards and southwards, in one complete
revolution about the Sun. The Earth also has an axial tilt of about
23.4°.The altitude of the sun can also be explained by use of solar zenith angle (θz)
which is a vertical angle between Sun’s rays and a line perpendicular to the
horizontal plane through the point (θ z =90 - α). Solar azimuth angle (γs) is the
horizontal angle measured from south (in the northern hemisphere) to the
horizontal projection of the Sun’s rays.

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2.4 Nature of Solar Irradiation and the Solar Constant
Sunlight contains UV light which is a solar radiation in form of an electromagnetic
radiation given off by the Sun. Resulting from the intense temperature and
pressure at the core of the Sun, solar fusion takes place. Protons are converted into
helium atoms at a rate of 600 million tons per second. Since the output of this
process has lower energy than the protons that began, the fusion gives off a
tremendous amount of energy in the form of gamma rays. These gamma rays are
absorbed by particles in the Sun, and then re-emitted. Over the course of 200,000
years, photons of light make their journey through the radiation zone of the Sun.
Solar irradiation is the measure of the total incident solar radiation transmitted to
the surface of the Earth’s atmosphere in a given unit of time. Solar radiation from
the. Sun can be direct, diffuse nor reflected. Direct radiation, also called beam
radiation, is the solar radiation travelling on a straight line from the sun down to
the surface of the Earth. Diffuse radiation refers to the sunlight that has been
scattered by molecules and particles in the atmosphere but that has still made it
down to the surface of the earth. Unlike direct radiation, diffuse radiation doesn’t
have a definite direction. Reflected radiation describes the Sunlight that has been
reflected off of non-atmospheric surfaces such as the ground. The solar radiation
data are usually given in the form of global radiation on a horizontal surface and
solar and PV panels are usually positioned at an angle to the horizontal plane.
2.4.1: Sunlight
Photometry enables us determine the amount of light given off by the Sun in
terms of brightness perceived by the human eye. In photometry, a luminosity
function is used for the radiant power at each wavelength to give a different
weight to a particular wavelength that models human brightness sensitivity.
Photometric measurements began as early as the end of the 18th century
resulting in many different units of measurement, some of which cannot even
be converted owing to the relative meaning of brightness. However, the
luminous flux (or lux) is commonly used and is the measure of the perceived
power of light. Its unit, the lumen, is concisely defined as the luminous flux of
light produced by a light source that emits one candela of luminous intensity
over a solid angle of one steradian. The candela is the SI unit of luminous
intensity and it is the power emitted by a light source in a particular direction,
weighted by a luminosity function whereas a steradian is the SI unit for a solid
angle; the two-dimensional angle in three dimensional space that an object
subtends at a point.

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2.4.2: The Solar Constant
The is defined as the amount of solar energy received upon a unit surface by the
Earth’s atmosphere, perpendicular to the Sun’s direction and is usually
expressed in calories per square centimeter per minute, and in these units,
common values are in the range 1.89 to 1.9cm/minute. The determination of
the solar constant is facilitated by solar spectral-irradiance curves. These are
obtained with a recording spectrobolometer (a combined spectroscope and
bolometer for determining the wavelength distribution of radiant energy
emitted by a source) and referenced to a measurement obtained from a
pyrheliometer that determines the total radiation at the same time.
2.5. Fixed and Tracking Collectors
2.5.1 Fixed Collectors
Harnessing of solar energy can be done using either fixed or movable collectors.
Fixed collectors are mostly mounted on the places with maximum sunlight and at
relatively good angle in relation to the sun such as rooftops. The aim is to expose
The panel for maximum hours in a day without necessarily involving tracking
technologies and therefore a considerable reduction in installation and
maintenance cost is realized. As such, majority of the collectors are fixed type.
For fixed solar collectors therefore is very necessary to know the position of the
sun at various seasons and time s of the year so as to give the optimum orientation
of the collector during installation to give the maximum solar energy

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All year round. Since the focus of this project was to design a solar tracker device
To be used in Nairobi, the sun chart diagram of this locality is
By using this chart, we can almost definitively ascertain the position of the sun
during different time and seasons of the year such that we are able to fix the
payload, in this case a fixed solar panel or photovoltaic cell to give us the maximum
energy output. As previously discussed, it should be noted that fixed solar trackers
are cheaper and therefore more preferred around countries in the tropics region,
Kenya being no exception. In fact in chapter 3, the results will be
recorded and analyzed for both fixed and tracking solar panel to point out the
differences in efficiency. However, for countries beyond +10degrees North and -
10degrees South of Equator, there is serious need for solar tracking since the
Figure 2.1 Sun path in Pune

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number of sunshine hour’s maybe less and/or the position of the midday sun may
vary significantly. As is evident from this chart, the position of the sun in the sky is
highest in the period between the hours of 1200h and 1400h. For hours outside
this range, the solar collectors are obliquely oriented to the Sun and as a result,
only a fraction reaches the absorption surface of the solar collector since the
payload cannot track sun movements.
2.5.2: Tracking Collectors: Improved Efficiency
For a tracking collector, the theoretical extracted energy is calculated assuming
that the maximum radiation intensity I = 1100 W/m2is falling on the area which is
oriented perpendicularly to the direction of radiation. Taking the length of day t =
12h = 43200s, the intensity on the tracking collector which is always optimally
oriented facing the Sun is compared to that of a fixed collector which is oriented
perpendicularly to the direction of radiation only at noon. The collector area is
marked as So.

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CHAPTER: - 3
BLOCK DIAGRAM/FLOW CHART/ALGORITHM
3.1: Light Sensor Theory and Circuit of Sensor Used
Light detecting sensor that maybe used to build solar tracker include;
phototransistors, photodiodes, LDR and LLS05. A suitable, inexpensive, simple
and easy to interface photo sensor is analog LDR which amongst the light
sensors is the most common in electronics. It is usually in form of a photo
resistor made of cadmium sulfide (CdS) or gallium arsenide (GaAs).
Next in complexity is the photodiode followed by the phototransistor.
The solar tracker in this project uses a cadmium sulfide (CdS) photocell for light
sensing. This is the least expensive and least complex type of light sensor.
The CdS photocell is a passive component whose resistance in inversely
proportional to the amount of light intensity falling on it. To utilize the
photocell, it is placed in series with a resistor (B10K potentiometer in this
case). A voltage divider is thus formed and the output at the junction is
determined by the two resistances. Figure 1 illustrates the photocell circuit. In
this project, it was desired for the output voltage to increase as the light
intensity increases, so the photocell was placed in the top position as shown
below.
3.1.1 Construction and Operation of an LDR:-
The cadmium sulfide (CdS) or light dependent resistor (LDR) whose resistance is
inversely dependent on the amount of light falling on it, is known by many names
including the photo resistor, photoresistor, photoconductor, photoconductive cell,
or simply the photocell. A typical structure for a photoresistor uses an active
semiconductor layer that is deposited on an insulating substrate. The
Figure 2.2 LDR

17. 17
semiconductor is normally lightly doped to enable it to have the required level of
conductivity. Contacts are then placed either side of the exposed area. The photo-
resistor, CdS, or LDR finds many uses as a low cost photo sensitive element and was
used for many years in photographic light meters as well as in other applications
such as smoke, flame and burglar detectors, card readers and lighting controls for
street lamps [2]. Since this is
3.1.2 Light Sensor Design
As presented in Chapter above, the sun tracker uses a CdS photocell for light
detection. A complementary resistor value of 10 KΩ was used to construct the
circuit shown in Figure 3. 1 above. In this configuration, the output voltage will
increase as light intensity .The complementary resistor value should be chosen such
as to achieve the widest output range 15 possible. Photocell resistance was
measured under dark conditions, average light conditions, and bright light
conditions. The results are listed in Table below
3.2 Simple DC Motor and Driver Theory
A small simple Dc motor was chosen as the actuator in this project due to the
following advantages:
• Continuous duty operation.
• DC power supply (battery or speed controls)
• Reversibility at rest or during rotation with current limiting
• Relatively constant and adjustable speed
• High starting torque
A 5Volts DC motor was connected to pins 3 and 7 of the H-Bridge circuit and for
reversing and forward movement of the panel according to the signals received
from MSP 430 microcontroller. A small pulley drive was secured into the shaft of
the DC motor to link it with the axle holding the panel. This setup was sufficient to
provide the torque required to move the panel in solar tracking.
3.2.1 L293D H-Bridge
Due to power efficiency requirements of the project, this IC module was preferred
as opposed to H-Bridge using MOSFETS . It was chosen due to the following
features.
1. Wide Supply-Voltage Range: 4.5 V to 36 V
2. Separate Input-Logic Supply
3. Internal ESD Protection 17
4. Thermal Shutdown when very hot and puts itself OFF
5. High-Noise-Immunity Inputs

18. 18
6. Output Current 600mA per channel
7. Output Clamp Diodes for Inductive
Figure 3. 1: Pin out diagram for L293D
Inputs Outputs
A EN Y
H H H
L H L
X L Z
Table 3. 2: Function table for L293D H-Bridge
H=High
L=Low
X=Irrelevant
Z=High Impedance or OFF state
3.3 Microcontroller
Like a computer it has the common parts being central processing unit (CPU), some
RAM and input and output data bus. Principally a microcontroller was chosen to
design the tracker because of the following advantages:
 It formed part of embedded software design where a C-Program was loaded into
it
 It acted as a dedicated unit by being programmed for one purpose being motor
control.
 It had dedicated input device in addition to readily available programmer
Another advantage was the capabilities of programming the microcontroller using
a high level language, C which comes in the form of Code Composer Studio IDE from
Texas Instruments. The main advantage of C is its simplicity.

19. 19
3.3.1 Choice of Microcontroller
Since the project’s focus is on embedded software control, the microcontroller is
the heart of the system. The microcontroller selected for this project had to be able
to convert the analog photocell voltage into digital values and also provide four
output channels to control motor rotation. The MSP430G2553 was selected as it
satisfies these requirements in addition to already being provided with the class lab
kit. Specifically, it possesses the following three features to satisfy the specific
project goals [5].
3.4 Voltage Regulation
The L293D H-Bridge requires a regulated 5 volt supply voltage. The 7805 voltage
regulator was used to provide for that. Again when the MSP430 was used on
breadboard, required regulated 3.3volts which was provided by AMS1117.The
LM7805 voltage regulator the circuits used supply 5volts to the H-bridge is as
shown below.
Figure 3. 5: Voltage Regulator Circuit LM7805

20. 20
Notice functions of the capacitors include:
 Reducing the electromagnetic noise
 Provide voltage sink and voltage source
The diode prevents unwanted reversal of the current which could damage the chip
when it is powered.
The MSP-430 works with 3.3v power supply. Which is provided by voltage regulator
IC AMS1117 -3.3 v. The circuit diagram for AMS1117 is shown below
Figure 2PCB layout
Figure 1AMS1117

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3.5 The Design Tool
3.5.1 Code Compose Studio V5
This tool was chosen to implement software design and editing due to ease of use
and text editing capabilities. Moreover, Texas Instruments Kit was provided
together with the USB which further made loading code into the microcontroller
easier. Proteus Circuit editing Software was 20 used to draw the circuits required
and also for various simulations of various stages. The algorithms are as under: The
flow chart for the algorithm shown next is on the next page
3.5.2 Algorithm for Motor Control
This algorithm describes the general steps undertaken in the project.
1. Input the voltages from two LDRs,
2. Convert the above analog voltage signals into digital values between 0-1023,
3. Compare the two digital values and get the difference between them,
4. Set the difference as the error proportionate angle for simple DC motor rotation,
5. If the LDR voltages are equal stop DC motor.
The flow chart of Fig 3.6 illustrates the implementation of this algorithm. The input
into the system is two LDR voltages into pins 2 and 3 of MSP430 microcontroller.
The analog voltages are then converted to digital equivalents in the range 0-1023
microcontroller ADC. The 2 digital values are then compared and depending on
which is larger a signal is sent to the driver circuit which then drives the DC motor
to the direction with more light intensity. The diagram below shows the block
diagram of the solar tracking device

22. 22
Next, all the components are assembled as seen in the schematic diagram shown
below. However, since MSP430G2553 was not in Proteus, a close substitute was
used for schematic diagram purposes. It can be seen that the input stage comprise
the LDR and the divider circuit, which feeds the voltage outputs to the
microcontroller. The embedded software design entails the C-code loaded into the
MSP430 and the code used is shown at the appendix later in the report.
A simple DC motor is connected to the output pins 3 and 7 of the H-Bridge and the
outputs from the microcontroller are input into the H-Bridge through pins 2 and 6.
The function of the H-bridge id direction reversal of the DC motor Since the MSP is
not available in Proteus circuit maker and simulation software, it was
impossible to simulate the code after loading in the code composer. However, the
LDR inputs were simulated.
3.6. Construction
Ultimately the subparts of the project discussed in Chapters 3.1 through 3.5 were
consolidated to construct a complete project. Figure 3.7 provides a block diagram
of the project while Figure 3.8 provides a complete hardware schematic of the
project. Some additional construction details worth mentioning deal with the
motor and photocell. The motor was mounted to a wooden frame using a metallic
strip to provide a stable base for it. The photocell was mounted on a small wood
Platform with a broad base. The axle holding the photocell was connected to the
motor shaft using a small pulley drive.Fig3.7
Figure 3.5Simulation Diagram

23. 23
Figure 4MSP430G2553

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CHAPTER: - 4
METHODOLOGY
This solar tracking system will have three salient components; an input stage with
light sensors and potentiometer, a program in embedded software in
microcontroller and a driving circuit in form of H-bridge. The input stage is two LDRs
which are part of voltage divider circuit. L293D chip forms the driver circuit and a
C-program loaded into MSP430 forms the embedded software. All the parts are
designed independently and then assembled into a solar tracking system. Finally a
wooden frame is used to house the components required to execute the tracker.
5.1: Design and Results Analysis
Hardware and software portions of the project were separated into stages while
developing the overall system. The portions consisted of light detection, motor
driving, software tracking, and software enhancements. Building and testing
smaller Chapters of the system made the project more manageable and increased
efficiency by decreasing debugging time. The project performs the required
functions envisioned at the proposal phase. However, while satisfied with software
operation and simulation, less satisfaction was obtained from two hardware areas.
First, there is a potential for problems with motor/photocell movement due to the
photocell wires creating binding issues. There are two wires attached to the
photocell then connected to control circuit. Once the tracker has moved
approximately 30 to 45 degrees, the wires place a counter torque on the motor and
the motor slips. This creates positioning error. The present workaround for this is
to hold the photocell wires in a way as to keep them close to the wooden frame
which holds the photocell as the tracker moves. This problem will be discussed
further in Chapter 5. The second issue deals with the photocell. It was discovered
that the photocell needs to be shielded such that light can be directed narrowly to
its surface. This was done by placing a black vinyl tube around the photocell to
create a tunnel and help shield it from light that is not directly in its direct path.

25. 25
CHAPTER: 5
ADVANTAGES AND DISADVANATES
Solar energy offers many advantages over other forms of energy. Some of those
benefits are listed below:
1. The 89Petawatts of sunlight reaching the earth's surface is plentiful – almost
6,000 times more-compared to the 15 terawatts of average power
consumed by humans. Additionally, solar electric generation has the highest
power density (global mean of 170 W/m²) among renewable energies.
2. Solar power is pollution free during use.
3. Production end wastes and emissions are manageable using existing
pollution controls and end-of-use recycling technologies are also under
development.
4. Facilities can operate with little maintenance or intervention after initial
setup. Solar electric generation is economically superior where grid connection
or fuel transport is difficult, more costly or impossible. Examples include
satellites, island communities, remotely locations such as ocean vessels.
5. When grid-connected, solar electric generation can displace the highest cost
electricity during times of peak demand (in most climatic regions), can reduce
grid loading, and can eliminate the need for local battery power for use in times
of darkness and high local demand; such application is encouraged by net
metering.
6. Grid-connected solar electricity can be used locally thus reducing
transmission/distribution losses (transmission losses are approximately 7.2% in
mostsystems).
7. Once the initial capital cost of building a solar power plant has been spent,
operating costs are extremely low compared to existing power technologies.
Disadvantages of solar electricity
2. Solar electricity is almost always more expensive than electricity generated
by other sources.
3. Solar electricity is not available at night and is less available in cloudy weather
conditions
and therefore, a storage or complementary power system is required.
4. Limited power density: Average daily isolation in the contiguous Kenya is 3-
7kW·h/m² and on average lower in Europe where isolation is lower annually.
5. Solar cells produce DC which must be converted to AC (using a grid tie
inverter) when used in currently existing distribution grids. This incurs an
energy loss of 4-12%.

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CHAPTER: 6
SCOPE OF IMPROVEMENT
6.1: Future Work and Recommendations
The goals of this project were purposely kept within what was believed to be
attainable within the allotted timeline and resources. As such, many improvements
can be made upon this initial design. That being said, it is felt that this design
represents a functioning miniature scale model which could be replicated to a
much larger scale. The following recommendations are provided
as ideas for future expansion of this project:
Remedy the motor binding problems due to the photo sensor leads. This could be
done with some use of easy to bend cables which don’t necessarily exert any force
on the motor when it is turning the solar panel. Alternatively, a smaller gauge wire,
a larger motor with more torque, or a combination of some or all of these ideas.
Increase the sensitivity and accuracy of tracking by using a different light sensor. A
photo transistor with an amplification circuit would provide improved resolution
and a better tracking accuracy/precision. Use of components used. Utilize a dual-
axis design versus a single-axis to increase tracking accuracy. Future solar project
should use a microcontroller which can be used as a standalone unit in the
fabricated circuit without the use of the programmer kit


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CHPATER: 7
Conclusion
This project has presented a means of controlling a sun tracking array with an
embedded microcontroller system. Specifically, it demonstrates a working
software solution for maximizing solar cell output by positioning a solar array at the
point of maximum light intensity. This project presents a method of searching for
and tracking the sun and resetting itself for a new day. While the project has
limitations, particularly in hardware areas discussed in Chapter 3 and Chapter 4,
this provides an opportunity for expansion of the current project in future years
REFERENCES
[1] A.K. Saxena and V. Dutta, “A versatile microprocessor based controller for solar
tracking,” in Proc. IEEE, 1990, pp. 1105 – 1109.
[2] T.A. Papalias and M. Wong, “Making sense of light sensors,”
http://www.embedded.com, 2006.
[3] R. Condit and D. W. Jones, “Simple DC motor fundamentals,” Texas Instruments.
Publication AN907, pp. 1 – 22, 2004.
[4] Texas Instruments., “MSP430G2553 Datasheet,” www.ti.com, 2001
[5] “Fabrication of Dual-Axis Solar Tracking Controller Project”, Nader Barsoum,
Curtin
University, Sarawak, Malaysia, Intelligent Control and Automation, 2011, 2, 57-68.
ABBREVIATIONS AND ACRONYMS
ADC Analog to Digital Converter
EEPROM Electrical Erasable programmable Read Only Memory
D Diode
DC Direct current
GND Ground
I Current
I/O Input/ Output
IDE Integrated Development Environment
LDR Light Dependent Resistor
LED Light Emitting Diode
LUX Luminous Flux
LED Light Emitting Diode
MAX Maximum

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MCU Microcontroller
MIN Minimum
VCC Supply voltage
UV Ultra Violet Light
PCB Printed Circuit Board
PV Photovoltaic panels
R Resistor
GaAs gallium arsenide

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APPENDIX: LIST OF COMPONENTS USED AND ESTIMATED COST
COMPONETNTS COST(in Rs)
MSP430G2553 200
L293D 50
POTENTIOMETER 20
LM7805 10
AMS1117-3.3V 20
CAPACETOR 10µF 2
RESISTOR 47KΩ 1
DC BATTERY 9V 20
SCREW TERMINAL (mo2) 5
JUMPER WIRES 25
LDR 20
SINGLE STAND WIRES 20
DC MOTER 150
TOTAL 543

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APPENDIX: code used in the microcontroller
#include "msp430.h"
#define ADC_CHANNELS 2
unsigned int samples[ADC_CHANNELS];
#define LED1 BIT4
#define LED2 BIT6
#define SENSOR_LEFT BIT0
#define SENSOR_GND BIT2
#define SENSOR_RIGHT BIT1
#define SENSOR_GND1 BIT3
#define RED_LED LED1
#define GRN_LED LED2
void ConfigureAdc(void){
ADC10CTL1 = INCH_1 | ADC10DIV_0 | CONSEQ_3 | SHS_0;
ADC10CTL0 = SREF_0 | ADC10SHT_2 | MSC | ADC10ON | ADC10IE;
ADC10AE0 =SENSOR_LEFT + SENSOR_RIGHT ;
ADC10DTC1 = ADC_CHANNELS;
}
void main(void) {
WDTCTL = WDTPW | WDTHOLD;
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BCSCTL1 = CALBC1_1MHZ;
DCOCTL = CALDCO_1MHZ;
BCSCTL2 &= ~(DIVS_3);
P1DIR = 0; /* set as inputs */
P1SEL = 0; /* set as digital I/Os */
P1OUT = 0; /* set resistors as pull-downs */
P1REN = 0xFF; /* enable pull-down resistors */
P2DIR = 0; /* set as inputs */
P2SEL = 0; /* set as digital I/Os */
P2OUT = 0; /* set resistors as pull-downs */
P2REN = 0xFF; /* enable pull-down resistors */
P1REN &= ~(LED1 | LED2); /* disable pull-up/downs */
P1DIR |= (LED1 | LED2); /* configure as outputs */

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P1REN &= ~(SENSOR_GND |SENSOR_GND1); /* disable pull-up/down */
P1OUT &= ~(SENSOR_GND|SENSOR_GND); /* SENSOR_GND should be at
GND
*/
P1DIR |= (SENSOR_GND |SENSOR_GND1); /* SENSOR_GND must be an
output
*/
P1REN |= (SENSOR_LEFT|SENSOR_RIGHT); /* enable pull-up on SENSOR */
P1IN |= (SENSOR_LEFT|SENSOR_RIGHT); /* set resistor as pull-up */
ConfigureAdc();
__enable_interrupt();
while (1) {
__delay_cycles(1000);
ADC10CTL0 &= ~ENC;
while (ADC10CTL1 & BUSY);
ADC10SA = (unsigned int)samples;
ADC10CTL0 |= ENC + ADC10SC;
__bis_SR_register(CPUOFF + GIE);
if (samples[0] < samples[1]) {
P1OUT |=RED_LED;
P1OUT &= ~(GRN_LED);
} else if (samples[0] == samples[1]) {
P1OUT &= ~(RED_LED);
P1OUT &= ~(GRN_LED);
} else {
P1OUT |= GRN_LED;
P1OUT &= ~(RED_LED);
}
}
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR (void){
__bic_SR_register_on_exit(CPUOFF);
}