DUAL AXIS SOLAR TRACKING SYSTEMMAJOR PROJECTSubmitted to Rajiv
Gandhi Proudyogiki VishwavidyalayaTowards Partial Fulfillment of
the Degree ofBACHELOR OF ENGINEERING(Electrical & Electronics
Engineering)
GUIDED BYMd. Firoz
SUBMITTED BYAshish VermaChhotelal SahuDeepak KumarRohit
PandeySwapnil Sonkusare
ELECTRICAL & ELECTRONICS ENGINEERINGDEPARTMENTINSTITUTE OF
ENGINEERING & SCIENCEIPS ACADEMY INDORE2014-15
ELECTRICAL & ELECTRONICS ENGINEERINGDEPARTMENTINSTITUTE OF
ENGINEERING & SCIENCEIPS ACADEMY INDORE
CERTIFICATE
We are pleased to certify that the major project entitled DUAL
AXIS SOLAR TRACKINGSYSTEM submitted by following is accepted.
Ashish Verma 0808EX111010Chhotelal Sahu 0808EX111014Deepak Kumar
0808EX111015Rohit Pandey 0808EX111046Swapnil Sonkusare
0808EX111059
INTERNAL EXAMINER EXTERNAL EXAMINERDate: Date:A c k n o w l e d
g e m e n t
It is our great pleasure to express our profound gratitude to
our esteemed guide Md.Firoz, Assistant Professor, Electrical and
Electronics Engg. Dept., IES IPS Academy Indore for their valuable
inspiration, able guidance and untiring help, which enabled us to
do this project.We are grateful to Mr. B. N. Phadke, Professor and
Department Head of Electrical and ElectronicsEngineering, IES IPS
Academy Indore, for his keenness towards this work and efforts put
in, and also for sharing his valuable time to our problems and
providing useful solutions.At this juncture we also take this
opportunity to express our deep gratitude to all the faculties
ofElectrical and Electronics Engineering Department, for their
appreciation and moral support.We are also thankful to all our
friends who helped us directly or indirectly to bring the
dissertationwork to the present shape.
Date: Ashish Verma Chhotelal Sahu Deepak Kumar Rohit Pandey
Swapnil Sonkusare
Abstract
Solar energy is the most readily available energy available on
earth. The energy of the sun is used since ancient times. With fast
growing environmental concerns over the climate change risks
associated with power generation with non-renewable energy, solar
power has been the best answer over the decades. However, the
output power of the solar cell panel is highly affected by the
sunlight incident angle. By tracking the direction of solar panel
to the sun, it can always be pointing at the optimum angle to
harvest the maximum solar energy throughout a day or a year. We
proposed a Dual axis Solar Tracking System in which dual axis solar
photovoltaic panel is characterized by the capability to move in
horizontal and vertical directions. The proposed sun tracking
system will use 4 photo resistors, which will be mounted on the
sides of the photo module. By these photo resistors the solar
tracking system will become more sensitive and will allow
determining a more accurate location of the sun. This tracking
system will make the solar photovoltaic array more efficient by
keeping the panels face perpendicular to the sun and therefore
extract maximum solar energy resulting into increased overall
efficiency.
Table of ContentsTitle Page No.Abstract ivTable of Contents
vList of Figures viiList of Tables ixList of Abbreviation, Symbols
xChapter 1 Introduction 1-31.1 Overview 1Chapter 2 Project
Background & Literature Review 4-162.1 Solar Radiation 42.2
Insolation 52.3 Projection Effect 62.4 Solar Photovoltaic Power
72.5 Photovoltaic Cell 8 2.5.1 Working of Photovoltaic Cell 8 2.5.2
PV Module 8 2.5.3 PV Modeling 92.6 Types of Solar Panels 11 2.6.1
Monocrystalline Solar Panel 11 2.6.2 Polycrystalline Solar Panel 13
2.6.3 Amorphous Solar Panel 132.7 Literature Review 14Chapter 3
Solar Tracker 16-253.1 Introduction 163.2 Need for Solar Tracker
163.3 Types of Solar Tracker 19 3.3.1 Single Axis Trackers 19
3.3.1.1 Horizontal Single Axis Tracker (HSAT) 20 3.3.1.2 Horizontal
Single Axis Tracker with Tilted Modules (HTSAT) 20 3.3.1.3 Vertical
Single Axis Tracker (VSAT) 213.3.1.4 Tilted Single Axis Tracker
(TSAT) 213.3.1.5 Polar Aligned Single Axis Trackers (PASAT) 21
3.3.2 Dual Axis Trackers 223.3.2.1 TipTilt Dual Axis Tracker
(TTDAT) 223.3.2.2 Azimuth-Altitude Dual Axis Tracker (AADAT) 233.4
Drive Type used in the Trackers 23 3.4.1 Active Tracker 23 3.4.2
Passive Tracker 24 3.4.3 Chronological Tracker 24 3.4.4 Manual
Tracking 25Chapter 4 Design of Solar Tracker 26-354.1 Proposed
Scheme 264.2 Components to be Used in Project 274.2.1
Microcontroller 8051 274.2.2 Pin Description 284.2.3 LDR 304.2.4
Comparator Circuit 324.2.5 DC Motor 324.2.6 Interfacing DC Motor
with 8051 34Chapter 5 Conclusion 35References 36
List of FiguresFigure Title Page. No1.1 Illustration of Solar
Angles: Altitude Angle () & Azimuthal Angle () 22.1 Declination
Angles 52.2 Monthly available Insolation in Wm2 for the Equator,
30, 60, And 90 N 62.3 Effect of Angle on the Area that Intercepts
an Incoming Beam of Radiation. 62.4 Angle of Incidence to Solar
Cell 72.5 PV Generate Electricity when Irradiated by Sunlight 82.6
Photovoltaic Module 92.7 Single Diode Model of a PV Cell 92.8 I-V
Characteristics of a Solar Panel 102.9 P-V Characteristics Curve of
Photovoltaic Cell 112.10 Mono Crystalline Solar Panel 122.11
Polycrystalline Solar Panel 132.12 Amorphous Solar Panel 143.1
Graph between Direct Power Loss due to Misalignment vs Angle of
Incidence 183.2 Single Axis Tracker on a Horizontal Axis 203.3
Single Axis Tracker on a Vertical Axis 213.4 Single Axis Tracker on
a Tilted Axis 213.5 Dual Axis Tracker 224.1 Block Diagram of
Proposed System 264.2 Proposed Model of Dual Axis Solar Tracker
274.3 Control Algorithm 284.4 Pin Diagram of 8051 294.5 An LDR
304.6 Symbol of LDR 304.7 LDRs in a Voltage Divider Arrangement
314.8 Shadow Technique 314.10 Working of a Brushed DC Motor 334.11
Types of DC Motors 344.12 Interfacing Circuit of DC Motor with 8051
C 35List of TablesTable Title Page No3.1 Relation between Angle of
incidence and direct power loss 194.1 Truth table for L293D motor
driver IC 35
List of AbbreviationsPV- PhotovoltaicDOF - Degrees of FreedomPV
panels - Photovoltaic panelsMPPT - Maximum Power Point TrackingSCM
- Single-chip microcomputerDC - Direct CurrentHSAT - Horizontal
Single Axis TrackersVSAT - Vertical Single Axis TrackersAADAT -
Azimuth-Altitude Dual Axis Trackers- Altitude Angle- Azimuth
Angle
Chapter 1Introduction
1.1 OverviewDuring the last few years the renewable energy
sources like solar energy have gained much importance in all over
the world. Different types of renewable or green energy resources
like hydropower, wind power, and biomass energy are currently being
utilized for the supply of energy demand. Among the conventional
renewable energy sources, solar energy is the most essential and
prerequisite resource of sustainable energy [1, 2].Solar energy
refers to the conversion of the suns rays into useful forms of
energy, such as electricity or heat. A photovoltaic cell, commonly
called a solar cell or PV, is the technology used to convert solar
energy directly into electrical power. The physics of the PV cell
(solar cell) is very similar to the classical p-n junction diode.
Sunlight is composed of photons or particles of solar energy.
Semiconductor materials within the PV cell absorb sunlight which
knocks electrons from their atoms, allowing electrons to flow
through the material to produce electricity [3, 4]. Because of its
cleanliness, ubiquity, abundance, and sustainability, solar energy
has become well recognized and widely utilized [5].Different
researches estimate that covering 0.16% of the land on earth with
10% efficient solar conversion systems would provide 20 TW of
power, nearly twice the worlds consumption rate of fossil energy
[6]. This proves the potential of solar energy which in turn points
out the necessity of tracking mechanism in solar systems. The
tracking mechanism is an electromechanical system that ensures
solar radiation is always perpendicular to the surface of the
photovoltaic cells (solar cells) which maximizes energy harnessing
[7].Before the introduction of solar tracking methods, static solar
panels were positioned with a reasonable tilted angle based on the
latitude of the location. With the advancement in technology
introduced automated tracking systems which improve existing power
generation by 50% [8].Previous researchers used single axis
tracking system which follows only the suns daily motion[9]. But
the earth follows a complex motion that consists of the daily
motion and the annual motion.The daily motion causes the sun to
appear in the east to west direction over the earth whereas the
annual motion causes the sun to tilt at a particular angle while
moving along east to west direction[10].The suns location in the
sky relative to a location on the surface of the earth can be
specified by two angles as shown in Figure 1.1. They are the solar
altitude angle () and the solar azimuth angle (). Azimuth angle is
the angle between the suns position and the horizontal plane of the
earths surface while Altitude angle specifies the angle between a
vertical plane containing the solar disk and a line running due
south [11].
(Source: http://dx.doi.org/10.1155/2014/629717)Figure 1.1:
Illustration of the Solar Angles: Altitude Angle () & Azimuthal
Angle ()Solar tracking is best achieved when the tilt angle of the
solar tracking systems is synchronized with the seasonal changes of
the suns altitude. An ideal tracker would allow the solar modules
to point towards the sun, compensating for both changes in the
altitude angle of the sun (throughout the day) and latitudinal
offset of the sun (during seasonal changes). So the maximum
efficiency of the solar panel is not being used by single axis
tracking system whereas double axis tracking would ensure a cosine
effectiveness of one.In active tracking or continuous tracking, the
position of the sun in the sky during the day is continuously
determined by sensors. The sensors will trigger the motor or
actuator to move the mounting system so that the solar panels will
always face the sun throughout the day. If the sunlight is not
perpendicular to the tracker, then there will be a difference in
light intensity on one light sensor compared to another. This
difference can be used to determine in which direction the tracker
has to be tilted in order to be perpendicular to the sun. This
method of sun tracking is reasonably accurate except on very cloudy
days when it is hard for the sensors to determine the position of
the sun in the sky [12].Passive tracker, unlike an active tracker
which determines the position of the sun in the sky, moves in
response to an imbalance in pressure between two points at both
ends of the tracker. The 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.
However, this method of sun tracking is not accurate [13,14].A
chronological tracker is a time-based tracking system where the
structure is moved at a fixed rate throughout the day as well for
different months. Thus the motor or actuator is controlled to
rotate at a slow average rate of one revolution per day (15 per
hour). This method of sun tracking is more energy efficient [15].To
track the suns movement accurately dual axis tracking system is
necessary. The active/continuous tracking system tracks the sun for
light intensity variation with precision. Hence, the power gain
from this system is very high [16]. But to achieve this power gain
the system uses two different motors continuously for two different
axes. Finally the motivation of the project was to design and
implement a dual axis solar tracking system.A simple energy
efficient and rugged tracking model is proposed in this project in
order to build a dual axis solar tracker. To track the suns daily
motion, that is, from east to west direction, a pair of light
sensors is used and to track the seasonal motion of the sun real
time clock (RTC) is used to create the accurate azimuth angle from
some predetermined parameters. The light intensity is compared by
microcontroller and it generates the suitable control signals to
move the motors in proper direction. So a driver circuit is used to
increase the voltage and current level for the operation of the
motors. Two geared DC motors are used for rotating the solar module
in two different axes which ensures tracking the point of maximum
light intensity.
Chapter 2Project Background & Literature Review
2.1 Solar RadiationThe sun, at an estimated temperature of 5800
K [17], emits high amounts of energy in the form of radiation,
which reaches the planets of the solar system. Sunlight has two
components, the direct beam and diffuse beam. Direct radiation
(also called beam radiation) is the solar radiation of the sun that
has not been scattered (causes shadow). Direct beam carries about
90% of the solar energy, and the diffuse sunlight" that carries the
remainder. The diffuse portion is the blue sky on a clear day and
increases as a proportion on cloudy day .The diffuse radiation is
the sun radiation that has been scattered (complete radiation on
cloudy days). Reflected radiation is the incident radiation (beam
and diffuse) that has been reflected by the earth. The sum of
beams, diffuse and reflected radiation is considered as the global
radiation on a surface. As the majority of the energy is in the
direct beam, maximizing collection requires the sun to be visible
to the panels as long as possible [18].Declination Angle - The
declination of the sun is the angle between the equator and a line
drawn from the centre of the Earth to the centre of the sun as
shown in Figure 2.1. The declination is maximum (23.450) on the
summer/winter (in India 21 June and 22 December) The declination
angle () varies seasonally due to the tilt of the Earth on its axis
of rotation and the rotation of theEarth around the sun. If the
Earth were not tilted on its axis of rotation, the declination
would always be 0. However, the Earth is tilted by 23.45 and the
declination angle varies plus or minus this amount. Only at the
spring and fall equinoxes is the declination angle equal to
0[19].Hour Angle - The Hour Angle is the angular distance that the
earth has rotated in a day. It is equal to 15 degrees multiplied by
the number of hours from local solar noon. This is based on the
nominal time, 24 hours, required for the earth to rotate once i.e.
360 degrees. Solar hour angle is zero when sun is straight over
head, negative before noon, and positive after noon (here noon
means 12.00 hour) [19].Solar Altitude () - The solar altitude is
the vertical angle between the horizontal and the line connecting
to the sun as shown in Figure 1.1. At sunset/sunrise altitude is 0
and is 90 degrees when the sun is at the zenith. The altitude
relates to the latitude of the sit, the declination angle and the
hour angle [20]
(Source: http://www.itacanet.org)Figure 2.1: Declination
AnglesSolar Azimuth ()-The azimuth angle is the angle within the
horizontal plane measured from true South or North. The azimuth
angle is measured clockwise from the zero azimuth [20]. 2.2
InsolationInsolation is a measure of solar radiation energy
received on a given surface area and recorded during a given time.
It is also called solar irradiation and expressed as hourly
irradiation if recorded during an hour, daily irradiation if
recorded during a day, for example. The unit recommended by the
World Meteorological Organization is MJ/m2 (mega joules per square
meter) or J/cm2 (joules per square centimeter).Practitioners in the
business of solar energy may use the unit Wh/m2 (watt-hours per
square meter). If this energy is divided by the recording time in
hours, it is then a density of power called irradiance, expressed
in W/m2 (watts per square meter) [21]. Over the course of a year
the average solar radiation arriving at the top of the Earth's
atmosphere at any point in time is roughly 1366 watts per square
meter. The Sun's rays are attenuated as they pass through the
atmosphere, thus reducing the irradiance at the Earth's surface to
approximately 1000W/m2 for a surface perpendicular to the Sun's
rays at sea level on a clear day. The insolation of the sun can
also be expressed in Suns, where one Sun equals 1000 W/m2
(Source: http://www.physicalgeography.net)Figure 2.2: Monthly
values of available Insolation in Wm2 for the Equator, 30, 60, and
90 North2.3 Projection EffectThe insolation into a surface is
largest when the surface directly faces the Sun. As the angle
increases between the direction at a right angle to the surface and
the direction of the rays of sunlight, the insolation is reduced in
proportion to cosine of the angle as illustrated in Figure 2.3.This
'projection effect' is the main reason why the Polar Regions are
much colder than equatorial regions on Earth. On an annual average
the poles receive less insolation than does the equator, because at
the poles the Earth's surface are angled away from the Sun
[23].
(Source: http://en.wikipedia.org/wiki/Insolation)Figure 2.3:
Effect of Angle on the Area that Intercepts an Incoming Beam of
Radiation2.4 Photovoltaic PowerSolar panels are formed out of solar
cells that are connected in parallel or series. When connected in
series, there is an increase in the overall voltage, connected in
parallel increases the overall current. Each individual solar cell
is typically made out of crystalline silicon, although other types
such as ribbon and thin-film silicone are gaining
popularity.Because the PV cells generate a current, cells/panels
can be modeled as DC current sources. The amount of current a PV
panel produces has a direct correlation with the intensity of light
the panel is absorbing as illustration shown in Figure 2.4
(Source: Google Image)Figure 2.4: Angle of Incidence to Solar
CellThe normal to the cell is perpendicular to the cells exposed
face. The sunlight comes in and strikes the panel at an angle. The
angle of the sunlight to the normal is the angle of incidence
().Assuming the sunlight is staying at a constant intensity () the
available sunlight to the solar cell for power generation (W) can
be calculated as below:W = A* cos() (i) = (Pmax/W)*100% (ii)Here, A
represents some limiting conversion factor in the design of the
panel because they cannot convert 100% of the sunlight absorbed
into electrical energy. By this calculation, the maximum power
generated will be when the sunlight is hitting the PV cell along
its normal and no power will be generated when the sunlight is
perpendicular to the normal. With a fixed solar panel, there is
significant power lost during the day because the panel is not kept
perpendicular to the suns rays.A tracking system can keep the angle
of incidence within a certain margin and would be able to maximize
the power generated [24].2.5 Photovoltaic Cell2.5.1 Working of
Photovoltaic CellA photovoltaic cell or photoelectric cell is a
semiconductor device that converts light to electrical energy by
photovoltaic effect. If the energy of photon of light is greater
than the band gap then the electron is emitted and the flow of
electrons creates current as shown in figure 2.5. However a
photovoltaic cell is different from a photodiode. In a photodiode
light falls on n channel of the semiconductor junction and gets
converted into current or voltage signal but a photovoltaic cell is
always forward biased.