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.